Initial Vexta Core v0.1.0 release

src/util/asmap.cpp

@@ -0,0 +1,185 @@
+// Copyright (c) 2019-2020 The DigiByte Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include <map>
+#include <vector>
+#include <assert.h>
+#include <crypto/common.h>
+
+namespace {
+
+constexpr uint32_t INVALID = 0xFFFFFFFF;
+
+uint32_t DecodeBits(std::vector<bool>::const_iterator& bitpos, const std::vector<bool>::const_iterator& endpos, uint8_t minval, const std::vector<uint8_t> &bit_sizes)
+{
+    uint32_t val = minval;
+    bool bit;
+    for (std::vector<uint8_t>::const_iterator bit_sizes_it = bit_sizes.begin();
+        bit_sizes_it != bit_sizes.end(); ++bit_sizes_it) {
+        if (bit_sizes_it + 1 != bit_sizes.end()) {
+            if (bitpos == endpos) break;
+            bit = *bitpos;
+            bitpos++;
+        } else {
+            bit = 0;
+        }
+        if (bit) {
+            val += (1 << *bit_sizes_it);
+        } else {
+            for (int b = 0; b < *bit_sizes_it; b++) {
+                if (bitpos == endpos) return INVALID; // Reached EOF in mantissa
+                bit = *bitpos;
+                bitpos++;
+                val += bit << (*bit_sizes_it - 1 - b);
+            }
+            return val;
+        }
+    }
+    return INVALID; // Reached EOF in exponent
+}
+
+enum class Instruction : uint32_t
+{
+    RETURN = 0,
+    JUMP = 1,
+    MATCH = 2,
+    DEFAULT = 3,
+};
+
+const std::vector<uint8_t> TYPE_BIT_SIZES{0, 0, 1};
+Instruction DecodeType(std::vector<bool>::const_iterator& bitpos, const std::vector<bool>::const_iterator& endpos)
+{
+    return Instruction(DecodeBits(bitpos, endpos, 0, TYPE_BIT_SIZES));
+}
+
+const std::vector<uint8_t> ASN_BIT_SIZES{15, 16, 17, 18, 19, 20, 21, 22, 23, 24};
+uint32_t DecodeASN(std::vector<bool>::const_iterator& bitpos, const std::vector<bool>::const_iterator& endpos)
+{
+    return DecodeBits(bitpos, endpos, 1, ASN_BIT_SIZES);
+}
+
+
+const std::vector<uint8_t> MATCH_BIT_SIZES{1, 2, 3, 4, 5, 6, 7, 8};
+uint32_t DecodeMatch(std::vector<bool>::const_iterator& bitpos, const std::vector<bool>::const_iterator& endpos)
+{
+    return DecodeBits(bitpos, endpos, 2, MATCH_BIT_SIZES);
+}
+
+
+const std::vector<uint8_t> JUMP_BIT_SIZES{5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30};
+uint32_t DecodeJump(std::vector<bool>::const_iterator& bitpos, const std::vector<bool>::const_iterator& endpos)
+{
+    return DecodeBits(bitpos, endpos, 17, JUMP_BIT_SIZES);
+}
+
+}
+
+uint32_t Interpret(const std::vector<bool> &asmap, const std::vector<bool> &ip)
+{
+    std::vector<bool>::const_iterator pos = asmap.begin();
+    const std::vector<bool>::const_iterator endpos = asmap.end();
+    uint8_t bits = ip.size();
+    uint32_t default_asn = 0;
+    uint32_t jump, match, matchlen;
+    Instruction opcode;
+    while (pos != endpos) {
+        opcode = DecodeType(pos, endpos);
+        if (opcode == Instruction::RETURN) {
+            default_asn = DecodeASN(pos, endpos);
+            if (default_asn == INVALID) break; // ASN straddles EOF
+            return default_asn;
+        } else if (opcode == Instruction::JUMP) {
+            jump = DecodeJump(pos, endpos);
+            if (jump == INVALID) break; // Jump offset straddles EOF
+            if (bits == 0) break; // No input bits left
+            if (int64_t{jump} >= int64_t{endpos - pos}) break; // Jumping past EOF
+            if (ip[ip.size() - bits]) {
+                pos += jump;
+            }
+            bits--;
+        } else if (opcode == Instruction::MATCH) {
+            match = DecodeMatch(pos, endpos);
+            if (match == INVALID) break; // Match bits straddle EOF
+            matchlen = CountBits(match) - 1;
+            if (bits < matchlen) break; // Not enough input bits
+            for (uint32_t bit = 0; bit < matchlen; bit++) {
+                if ((ip[ip.size() - bits]) != ((match >> (matchlen - 1 - bit)) & 1)) {
+                    return default_asn;
+                }
+                bits--;
+            }
+        } else if (opcode == Instruction::DEFAULT) {
+            default_asn = DecodeASN(pos, endpos);
+            if (default_asn == INVALID) break; // ASN straddles EOF
+        } else {
+            break; // Instruction straddles EOF
+        }
+    }
+    assert(false); // Reached EOF without RETURN, or aborted (see any of the breaks above) - should have been caught by SanityCheckASMap below
+    return 0; // 0 is not a valid ASN
+}
+
+bool SanityCheckASMap(const std::vector<bool>& asmap, int bits)
+{
+    const std::vector<bool>::const_iterator begin = asmap.begin(), endpos = asmap.end();
+    std::vector<bool>::const_iterator pos = begin;
+    std::vector<std::pair<uint32_t, int>> jumps; // All future positions we may jump to (bit offset in asmap -> bits to consume left)
+    jumps.reserve(bits);
+    Instruction prevopcode = Instruction::JUMP;
+    bool had_incomplete_match = false;
+    while (pos != endpos) {
+        uint32_t offset = pos - begin;
+        if (!jumps.empty() && offset >= jumps.back().first) return false; // There was a jump into the middle of the previous instruction
+        Instruction opcode = DecodeType(pos, endpos);
+        if (opcode == Instruction::RETURN) {
+            if (prevopcode == Instruction::DEFAULT) return false; // There should not be any RETURN immediately after a DEFAULT (could be combined into just RETURN)
+            uint32_t asn = DecodeASN(pos, endpos);
+            if (asn == INVALID) return false; // ASN straddles EOF
+            if (jumps.empty()) {
+                // Nothing to execute anymore
+                if (endpos - pos > 7) return false; // Excessive padding
+                while (pos != endpos) {
+                    if (*pos) return false; // Nonzero padding bit
+                    ++pos;
+                }
+                return true; // Sanely reached EOF
+            } else {
+                // Continue by pretending we jumped to the next instruction
+                offset = pos - begin;
+                if (offset != jumps.back().first) return false; // Unreachable code
+                bits = jumps.back().second; // Restore the number of bits we would have had left after this jump
+                jumps.pop_back();
+                prevopcode = Instruction::JUMP;
+            }
+        } else if (opcode == Instruction::JUMP) {
+            uint32_t jump = DecodeJump(pos, endpos);
+            if (jump == INVALID) return false; // Jump offset straddles EOF
+            if (int64_t{jump} > int64_t{endpos - pos}) return false; // Jump out of range
+            if (bits == 0) return false; // Consuming bits past the end of the input
+            --bits;
+            uint32_t jump_offset = pos - begin + jump;
+            if (!jumps.empty() && jump_offset >= jumps.back().first) return false; // Intersecting jumps
+            jumps.emplace_back(jump_offset, bits);
+            prevopcode = Instruction::JUMP;
+        } else if (opcode == Instruction::MATCH) {
+            uint32_t match = DecodeMatch(pos, endpos);
+            if (match == INVALID) return false; // Match bits straddle EOF
+            int matchlen = CountBits(match) - 1;
+            if (prevopcode != Instruction::MATCH) had_incomplete_match = false;
+            if (matchlen < 8 && had_incomplete_match) return false; // Within a sequence of matches only at most one should be incomplete
+            had_incomplete_match = (matchlen < 8);
+            if (bits < matchlen) return false; // Consuming bits past the end of the input
+            bits -= matchlen;
+            prevopcode = Instruction::MATCH;
+        } else if (opcode == Instruction::DEFAULT) {
+            if (prevopcode == Instruction::DEFAULT) return false; // There should not be two successive DEFAULTs (they could be combined into one)
+            uint32_t asn = DecodeASN(pos, endpos);
+            if (asn == INVALID) return false; // ASN straddles EOF
+            prevopcode = Instruction::DEFAULT;
+        } else {
+            return false; // Instruction straddles EOF
+        }
+    }
+    return false; // Reached EOF without RETURN instruction
+}

src/util/asmap.h

@@ -0,0 +1,15 @@
+// Copyright (c) 2019-2020 The DigiByte Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef DIGIBYTE_UTIL_ASMAP_H
+#define DIGIBYTE_UTIL_ASMAP_H
+
+#include <stdint.h>
+#include <vector>
+
+uint32_t Interpret(const std::vector<bool> &asmap, const std::vector<bool> &ip);
+
+bool SanityCheckASMap(const std::vector<bool>& asmap, int bits);
+
+#endif // DIGIBYTE_UTIL_ASMAP_H

src/util/bip32.cpp

@@ -0,0 +1,66 @@
+// Copyright (c) 2019-2020 The DigiByte Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include <sstream>
+#include <stdio.h>
+#include <tinyformat.h>
+#include <util/bip32.h>
+#include <util/strencodings.h>
+
+
+bool ParseHDKeypath(const std::string& keypath_str, std::vector<uint32_t>& keypath)
+{
+    std::stringstream ss(keypath_str);
+    std::string item;
+    bool first = true;
+    while (std::getline(ss, item, '/')) {
+        if (item.compare("m") == 0) {
+            if (first) {
+                first = false;
+                continue;
+            }
+            return false;
+        }
+        // Finds whether it is hardened
+        uint32_t path = 0;
+        size_t pos = item.find("'");
+        if (pos != std::string::npos) {
+            // The hardened tick can only be in the last index of the string
+            if (pos != item.size() - 1) {
+                return false;
+            }
+            path |= 0x80000000;
+            item = item.substr(0, item.size() - 1); // Drop the last character which is the hardened tick
+        }
+
+        // Ensure this is only numbers
+        if (item.find_first_not_of( "0123456789" ) != std::string::npos) {
+            return false;
+        }
+        uint32_t number;
+        if (!ParseUInt32(item, &number)) {
+            return false;
+        }
+        path |= number;
+
+        keypath.push_back(path);
+        first = false;
+    }
+    return true;
+}
+
+std::string FormatHDKeypath(const std::vector<uint32_t>& path)
+{
+    std::string ret;
+    for (auto i : path) {
+        ret += strprintf("/%i", (i << 1) >> 1);
+        if (i >> 31) ret += '\'';
+    }
+    return ret;
+}
+
+std::string WriteHDKeypath(const std::vector<uint32_t>& keypath)
+{
+    return "m" + FormatHDKeypath(keypath);
+}

src/util/bip32.h

@@ -0,0 +1,20 @@
+// Copyright (c) 2019-2020 The DigiByte Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef DIGIBYTE_UTIL_BIP32_H
+#define DIGIBYTE_UTIL_BIP32_H
+
+#include <attributes.h>
+#include <string>
+#include <vector>
+#include <cstdint>
+
+/** Parse an HD keypaths like "m/7/0'/2000". */
+[[nodiscard]] bool ParseHDKeypath(const std::string& keypath_str, std::vector<uint32_t>& keypath);
+
+/** Write HD keypaths as strings */
+std::string WriteHDKeypath(const std::vector<uint32_t>& keypath);
+std::string FormatHDKeypath(const std::vector<uint32_t>& path);
+
+#endif // DIGIBYTE_UTIL_BIP32_H

src/util/bytevectorhash.cpp

@@ -0,0 +1,18 @@
+// Copyright (c) 2018 The DigiByte Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include <crypto/siphash.h>
+#include <random.h>
+#include <util/bytevectorhash.h>
+
+ByteVectorHash::ByteVectorHash()
+{
+    GetRandBytes(reinterpret_cast<unsigned char*>(&m_k0), sizeof(m_k0));
+    GetRandBytes(reinterpret_cast<unsigned char*>(&m_k1), sizeof(m_k1));
+}
+
+size_t ByteVectorHash::operator()(const std::vector<unsigned char>& input) const
+{
+    return CSipHasher(m_k0, m_k1).Write(input.data(), input.size()).Finalize();
+}

src/util/bytevectorhash.h

@@ -0,0 +1,26 @@
+// Copyright (c) 2018 The DigiByte Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef DIGIBYTE_UTIL_BYTEVECTORHASH_H
+#define DIGIBYTE_UTIL_BYTEVECTORHASH_H
+
+#include <stdint.h>
+#include <vector>
+
+/**
+ * Implementation of Hash named requirement for types that internally store a byte array. This may
+ * be used as the hash function in std::unordered_set or std::unordered_map over such types.
+ * Internally, this uses a random instance of SipHash-2-4.
+ */
+class ByteVectorHash final
+{
+private:
+    uint64_t m_k0, m_k1;
+
+public:
+    ByteVectorHash();
+    size_t operator()(const std::vector<unsigned char>& input) const;
+};
+
+#endif // DIGIBYTE_UTIL_BYTEVECTORHASH_H

src/util/check.h

@@ -0,0 +1,75 @@
+// Copyright (c) 2019-2020 The DigiByte Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef DIGIBYTE_UTIL_CHECK_H
+#define DIGIBYTE_UTIL_CHECK_H
+
+#if defined(HAVE_CONFIG_H)
+#include <config/vexta-config.h>
+#endif
+
+#include <tinyformat.h>
+
+#include <stdexcept>
+
+class NonFatalCheckError : public std::runtime_error
+{
+    using std::runtime_error::runtime_error;
+};
+
+/**
+ * Throw a NonFatalCheckError when the condition evaluates to false
+ *
+ * This should only be used
+ * - where the condition is assumed to be true, not for error handling or validating user input
+ * - where a failure to fulfill the condition is recoverable and does not abort the program
+ *
+ * For example in RPC code, where it is undesirable to crash the whole program, this can be generally used to replace
+ * asserts or recoverable logic errors. A NonFatalCheckError in RPC code is caught and passed as a string to the RPC
+ * caller, which can then report the issue to the developers.
+ */
+#define CHECK_NONFATAL(condition)                                 \
+    do {                                                          \
+        if (!(condition)) {                                       \
+            throw NonFatalCheckError(                             \
+                strprintf("%s:%d (%s)\n"                          \
+                          "Internal bug detected: '%s'\n"         \
+                          "You may report this issue here: %s\n", \
+                    __FILE__, __LINE__, __func__,                 \
+                    (#condition),                                 \
+                    PACKAGE_BUGREPORT));                          \
+        }                                                         \
+    } while (false)
+
+#if defined(NDEBUG)
+#error "Cannot compile without assertions!"
+#endif
+
+/** Helper for Assert() */
+template <typename T>
+T get_pure_r_value(T&& val)
+{
+    return std::forward<T>(val);
+}
+
+/** Identity function. Abort if the value compares equal to zero */
+#define Assert(val) ([&]() -> decltype(get_pure_r_value(val)) { auto&& check = (val); assert(#val && check); return std::forward<decltype(get_pure_r_value(val))>(check); }())
+
+/**
+ * Assume is the identity function.
+ *
+ * - Should be used to run non-fatal checks. In debug builds it behaves like
+ *   Assert()/assert() to notify developers and testers about non-fatal errors.
+ *   In production it doesn't warn or log anything.
+ * - For fatal errors, use Assert().
+ * - For non-fatal errors in interactive sessions (e.g. RPC or command line
+ *   interfaces), CHECK_NONFATAL() might be more appropriate.
+ */
+#ifdef ABORT_ON_FAILED_ASSUME
+#define Assume(val) Assert(val)
+#else
+#define Assume(val) ([&]() -> decltype(get_pure_r_value(val)) { auto&& check = (val); return std::forward<decltype(get_pure_r_value(val))>(check); }())
+#endif
+
+#endif // DIGIBYTE_UTIL_CHECK_H

src/util/epochguard.h

@@ -0,0 +1,91 @@
+// Copyright (c) 2009-2010 Satoshi Nakamoto
+// Copyright (c) 2009-2020 The DigiByte Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef DIGIBYTE_UTIL_EPOCHGUARD_H
+#define DIGIBYTE_UTIL_EPOCHGUARD_H
+
+#include <threadsafety.h>
+
+#include <cassert>
+
+/** Epoch: RAII-style guard for using epoch-based graph traversal algorithms.
+ *     When walking ancestors or descendants, we generally want to avoid
+ * visiting the same transactions twice. Some traversal algorithms use
+ * std::set (or setEntries) to deduplicate the transaction we visit.
+ * However, use of std::set is algorithmically undesirable because it both
+ * adds an asymptotic factor of O(log n) to traversals cost and triggers O(n)
+ * more dynamic memory allocations.
+ *     In many algorithms we can replace std::set with an internal mempool
+ * counter to track the time (or, "epoch") that we began a traversal, and
+ * check + update a per-transaction epoch for each transaction we look at to
+ * determine if that transaction has not yet been visited during the current
+ * traversal's epoch.
+ *     Algorithms using std::set can be replaced on a one by one basis.
+ * Both techniques are not fundamentally incompatible across the codebase.
+ * Generally speaking, however, the remaining use of std::set for mempool
+ * traversal should be viewed as a TODO for replacement with an epoch based
+ * traversal, rather than a preference for std::set over epochs in that
+ * algorithm.
+ */
+
+class LOCKABLE Epoch
+{
+private:
+    uint64_t m_raw_epoch = 0;
+    bool m_guarded = false;
+
+public:
+    Epoch() = default;
+    Epoch(const Epoch&) = delete;
+    Epoch& operator=(const Epoch&) = delete;
+
+    bool guarded() const { return m_guarded; }
+
+    class Marker
+    {
+    private:
+        uint64_t m_marker = 0;
+
+        // only allow modification via Epoch member functions
+        friend class Epoch;
+        Marker& operator=(const Marker&) = delete;
+    };
+
+    class SCOPED_LOCKABLE Guard
+    {
+    private:
+        Epoch& m_epoch;
+
+    public:
+        explicit Guard(Epoch& epoch) EXCLUSIVE_LOCK_FUNCTION(epoch) : m_epoch(epoch)
+        {
+            assert(!m_epoch.m_guarded);
+            ++m_epoch.m_raw_epoch;
+            m_epoch.m_guarded = true;
+        }
+        ~Guard() UNLOCK_FUNCTION()
+        {
+            assert(m_epoch.m_guarded);
+            ++m_epoch.m_raw_epoch; // ensure clear separation between epochs
+            m_epoch.m_guarded = false;
+        }
+    };
+
+    bool visited(Marker& marker) const EXCLUSIVE_LOCKS_REQUIRED(*this)
+    {
+        assert(m_guarded);
+        if (marker.m_marker < m_raw_epoch) {
+            // marker is from a previous epoch, so this is its first visit
+            marker.m_marker = m_raw_epoch;
+            return false;
+        } else {
+            return true;
+        }
+    }
+};
+
+#define WITH_FRESH_EPOCH(epoch) const Epoch::Guard PASTE2(epoch_guard_, __COUNTER__)(epoch)
+
+#endif // DIGIBYTE_UTIL_EPOCHGUARD_H

src/util/error.cpp

@@ -0,0 +1,56 @@
+// Copyright (c) 2010-2020 The DigiByte Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include <util/error.h>
+
+#include <tinyformat.h>
+#include <util/system.h>
+#include <util/translation.h>
+
+bilingual_str TransactionErrorString(const TransactionError err)
+{
+    switch (err) {
+        case TransactionError::OK:
+            return Untranslated("No error");
+        case TransactionError::MISSING_INPUTS:
+            return Untranslated("Inputs missing or spent");
+        case TransactionError::ALREADY_IN_CHAIN:
+            return Untranslated("Transaction already in block chain");
+        case TransactionError::P2P_DISABLED:
+            return Untranslated("Peer-to-peer functionality missing or disabled");
+        case TransactionError::MEMPOOL_REJECTED:
+            return Untranslated("Transaction rejected by AcceptToMemoryPool");
+        case TransactionError::MEMPOOL_ERROR:
+            return Untranslated("AcceptToMemoryPool failed");
+        case TransactionError::INVALID_PSBT:
+            return Untranslated("PSBT is not well-formed");
+        case TransactionError::PSBT_MISMATCH:
+            return Untranslated("PSBTs not compatible (different transactions)");
+        case TransactionError::SIGHASH_MISMATCH:
+            return Untranslated("Specified sighash value does not match value stored in PSBT");
+        case TransactionError::MAX_FEE_EXCEEDED:
+            return Untranslated("Fee exceeds maximum configured by user (e.g. -maxtxfee, maxfeerate)");
+        case TransactionError::EXTERNAL_SIGNER_NOT_FOUND:
+            return Untranslated("External signer not found");
+        case TransactionError::EXTERNAL_SIGNER_FAILED:
+            return Untranslated("External signer failed to sign");
+        // no default case, so the compiler can warn about missing cases
+    }
+    assert(false);
+}
+
+bilingual_str ResolveErrMsg(const std::string& optname, const std::string& strBind)
+{
+    return strprintf(_("Cannot resolve -%s address: '%s'"), optname, strBind);
+}
+
+bilingual_str AmountHighWarn(const std::string& optname)
+{
+    return strprintf(_("%s is set very high!"), optname);
+}
+
+bilingual_str AmountErrMsg(const std::string& optname, const std::string& strValue)
+{
+    return strprintf(_("Invalid amount for -%s=<amount>: '%s'"), optname, strValue);
+}

src/util/error.h

@@ -0,0 +1,45 @@
+// Copyright (c) 2010-2020 The DigiByte Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef DIGIBYTE_UTIL_ERROR_H
+#define DIGIBYTE_UTIL_ERROR_H
+
+/**
+ * util/error.h is a common place for definitions of simple error types and
+ * string functions. Types and functions defined here should not require any
+ * outside dependencies.
+ *
+ * Error types defined here can be used in different parts of the
+ * codebase, to avoid the need to write boilerplate code catching and
+ * translating errors passed across wallet/node/rpc/gui code boundaries.
+ */
+
+#include <string>
+
+struct bilingual_str;
+
+enum class TransactionError {
+    OK, //!< No error
+    MISSING_INPUTS,
+    ALREADY_IN_CHAIN,
+    P2P_DISABLED,
+    MEMPOOL_REJECTED,
+    MEMPOOL_ERROR,
+    INVALID_PSBT,
+    PSBT_MISMATCH,
+    SIGHASH_MISMATCH,
+    MAX_FEE_EXCEEDED,
+    EXTERNAL_SIGNER_NOT_FOUND,
+    EXTERNAL_SIGNER_FAILED,
+};
+
+bilingual_str TransactionErrorString(const TransactionError error);
+
+bilingual_str ResolveErrMsg(const std::string& optname, const std::string& strBind);
+
+bilingual_str AmountHighWarn(const std::string& optname);
+
+bilingual_str AmountErrMsg(const std::string& optname, const std::string& strValue);
+
+#endif // DIGIBYTE_UTIL_ERROR_H

src/util/fees.cpp

@@ -0,0 +1,67 @@
+// Copyright (c) 2009-2010 Satoshi Nakamoto
+// Copyright (c) 2009-2020 The DigiByte Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include <util/fees.h>
+
+#include <policy/fees.h>
+#include <util/strencodings.h>
+#include <util/string.h>
+
+#include <map>
+#include <string>
+#include <vector>
+#include <utility>
+
+std::string StringForFeeReason(FeeReason reason)
+{
+    static const std::map<FeeReason, std::string> fee_reason_strings = {
+        {FeeReason::NONE, "None"},
+        {FeeReason::HALF_ESTIMATE, "Half Target 60% Threshold"},
+        {FeeReason::FULL_ESTIMATE, "Target 85% Threshold"},
+        {FeeReason::DOUBLE_ESTIMATE, "Double Target 95% Threshold"},
+        {FeeReason::CONSERVATIVE, "Conservative Double Target longer horizon"},
+        {FeeReason::MEMPOOL_MIN, "Mempool Min Fee"},
+        {FeeReason::PAYTXFEE, "PayTxFee set"},
+        {FeeReason::FALLBACK, "Fallback fee"},
+        {FeeReason::REQUIRED, "Minimum Required Fee"},
+    };
+    auto reason_string = fee_reason_strings.find(reason);
+
+    if (reason_string == fee_reason_strings.end()) return "Unknown";
+
+    return reason_string->second;
+}
+
+const std::vector<std::pair<std::string, FeeEstimateMode>>& FeeModeMap()
+{
+    static const std::vector<std::pair<std::string, FeeEstimateMode>> FEE_MODES = {
+        {"unset", FeeEstimateMode::UNSET},
+        {"economical", FeeEstimateMode::ECONOMICAL},
+        {"conservative", FeeEstimateMode::CONSERVATIVE},
+    };
+    return FEE_MODES;
+}
+
+std::string FeeModes(const std::string& delimiter)
+{
+    return Join(FeeModeMap(), delimiter, [&](const std::pair<std::string, FeeEstimateMode>& i) { return i.first; });
+}
+
+const std::string InvalidEstimateModeErrorMessage()
+{
+    return "Invalid estimate_mode parameter, must be one of: \"" + FeeModes("\", \"") + "\"";
+}
+
+bool FeeModeFromString(const std::string& mode_string, FeeEstimateMode& fee_estimate_mode)
+{
+    auto searchkey = ToUpper(mode_string);
+    for (const auto& pair : FeeModeMap()) {
+        if (ToUpper(pair.first) == searchkey) {
+            fee_estimate_mode = pair.second;
+            return true;
+        }
+    }
+    return false;
+}

src/util/fees.h

@@ -0,0 +1,18 @@
+// Copyright (c) 2009-2010 Satoshi Nakamoto
+// Copyright (c) 2009-2020 The DigiByte Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+#ifndef DIGIBYTE_UTIL_FEES_H
+#define DIGIBYTE_UTIL_FEES_H
+
+#include <string>
+
+enum class FeeEstimateMode;
+enum class FeeReason;
+
+bool FeeModeFromString(const std::string& mode_string, FeeEstimateMode& fee_estimate_mode);
+std::string StringForFeeReason(FeeReason reason);
+std::string FeeModes(const std::string& delimiter);
+const std::string InvalidEstimateModeErrorMessage();
+
+#endif // DIGIBYTE_UTIL_FEES_H

src/util/getuniquepath.cpp

@@ -0,0 +1,10 @@
+#include <random.h>
+#include <fs.h>
+#include <util/strencodings.h>
+
+fs::path GetUniquePath(const fs::path& base)
+{
+    FastRandomContext rnd;
+    fs::path tmpFile = base / HexStr(rnd.randbytes(8));
+    return tmpFile;
+}

src/util/getuniquepath.h

@@ -0,0 +1,19 @@
+// Copyright (c) 2021 The DigiByte Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef DIGIBYTE_UTIL_GETUNIQUEPATH_H
+#define DIGIBYTE_UTIL_GETUNIQUEPATH_H
+
+#include <fs.h>
+
+/**
+ * Helper function for getting a unique path
+ *
+ * @param[in] base  Base path
+ * @returns base joined with a random 8-character long string.
+ * @post Returned path is unique with high probability.
+ */
+fs::path GetUniquePath(const fs::path& base);
+
+#endif // DIGIBYTE_UTIL_GETUNIQUEPATH_H

src/util/golombrice.h

@@ -0,0 +1,43 @@
+// Copyright (c) 2018-2020 The DigiByte Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef DIGIBYTE_UTIL_GOLOMBRICE_H
+#define DIGIBYTE_UTIL_GOLOMBRICE_H
+
+#include <streams.h>
+
+#include <cstdint>
+
+template <typename OStream>
+void GolombRiceEncode(BitStreamWriter<OStream>& bitwriter, uint8_t P, uint64_t x)
+{
+    // Write quotient as unary-encoded: q 1's followed by one 0.
+    uint64_t q = x >> P;
+    while (q > 0) {
+        int nbits = q <= 64 ? static_cast<int>(q) : 64;
+        bitwriter.Write(~0ULL, nbits);
+        q -= nbits;
+    }
+    bitwriter.Write(0, 1);
+
+    // Write the remainder in P bits. Since the remainder is just the bottom
+    // P bits of x, there is no need to mask first.
+    bitwriter.Write(x, P);
+}
+
+template <typename IStream>
+uint64_t GolombRiceDecode(BitStreamReader<IStream>& bitreader, uint8_t P)
+{
+    // Read unary-encoded quotient: q 1's followed by one 0.
+    uint64_t q = 0;
+    while (bitreader.Read(1) == 1) {
+        ++q;
+    }
+
+    uint64_t r = bitreader.Read(P);
+
+    return (q << P) + r;
+}
+
+#endif // DIGIBYTE_UTIL_GOLOMBRICE_H

src/util/hash_type.h

@@ -0,0 +1,72 @@
+// Copyright (c) 2020-2021 The DigiByte Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef DIGIBYTE_UTIL_HASH_TYPE_H
+#define DIGIBYTE_UTIL_HASH_TYPE_H
+
+template <typename HashType>
+class BaseHash
+{
+protected:
+    HashType m_hash;
+
+public:
+    BaseHash() : m_hash() {}
+    explicit BaseHash(const HashType& in) : m_hash(in) {}
+
+    unsigned char* begin()
+    {
+        return m_hash.begin();
+    }
+
+    const unsigned char* begin() const
+    {
+        return m_hash.begin();
+    }
+
+    unsigned char* end()
+    {
+        return m_hash.end();
+    }
+
+    const unsigned char* end() const
+    {
+        return m_hash.end();
+    }
+
+    operator std::vector<unsigned char>() const
+    {
+        return std::vector<unsigned char>{m_hash.begin(), m_hash.end()};
+    }
+
+    std::string ToString() const
+    {
+        return m_hash.ToString();
+    }
+
+    bool operator==(const BaseHash<HashType>& other) const noexcept
+    {
+        return m_hash == other.m_hash;
+    }
+
+    bool operator!=(const BaseHash<HashType>& other) const noexcept
+    {
+        return !(m_hash == other.m_hash);
+    }
+
+    bool operator<(const BaseHash<HashType>& other) const noexcept
+    {
+        return m_hash < other.m_hash;
+    }
+
+    size_t size() const
+    {
+        return m_hash.size();
+    }
+
+    unsigned char* data() { return m_hash.data(); }
+    const unsigned char* data() const { return m_hash.data(); }
+};
+
+#endif // DIGIBYTE_UTIL_HASH_TYPE_H

src/util/hasher.cpp

@@ -0,0 +1,19 @@
+// Copyright (c) 2019 The DigiByte Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include <random.h>
+#include <util/hasher.h>
+
+#include <limits>
+
+SaltedTxidHasher::SaltedTxidHasher() : k0(GetRand(std::numeric_limits<uint64_t>::max())), k1(GetRand(std::numeric_limits<uint64_t>::max())) {}
+
+SaltedOutpointHasher::SaltedOutpointHasher() : k0(GetRand(std::numeric_limits<uint64_t>::max())), k1(GetRand(std::numeric_limits<uint64_t>::max())) {}
+
+SaltedSipHasher::SaltedSipHasher() : m_k0(GetRand(std::numeric_limits<uint64_t>::max())), m_k1(GetRand(std::numeric_limits<uint64_t>::max())) {}
+
+size_t SaltedSipHasher::operator()(const Span<const unsigned char>& script) const
+{
+    return CSipHasher(m_k0, m_k1).Write(script.data(), script.size()).Finalize();
+}

src/util/hasher.h

@@ -0,0 +1,99 @@
+// Copyright (c) 2019 The DigiByte Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef DIGIBYTE_UTIL_HASHER_H
+#define DIGIBYTE_UTIL_HASHER_H
+
+#include <crypto/siphash.h>
+#include <primitives/transaction.h>
+#include <uint256.h>
+
+class SaltedTxidHasher
+{
+private:
+    /** Salt */
+    const uint64_t k0, k1;
+
+public:
+    SaltedTxidHasher();
+
+    size_t operator()(const uint256& txid) const {
+        return SipHashUint256(k0, k1, txid);
+    }
+};
+
+class SaltedOutpointHasher
+{
+private:
+    /** Salt */
+    const uint64_t k0, k1;
+
+public:
+    SaltedOutpointHasher();
+
+    /**
+     * This *must* return size_t. With Boost 1.46 on 32-bit systems the
+     * unordered_map will behave unpredictably if the custom hasher returns a
+     * uint64_t, resulting in failures when syncing the chain (#4634).
+     *
+     * Having the hash noexcept allows libstdc++'s unordered_map to recalculate
+     * the hash during rehash, so it does not have to cache the value. This
+     * reduces node's memory by sizeof(size_t). The required recalculation has
+     * a slight performance penalty (around 1.6%), but this is compensated by
+     * memory savings of about 9% which allow for a larger dbcache setting.
+     *
+     * @see https://gcc.gnu.org/onlinedocs/gcc-9.2.0/libstdc++/manual/manual/unordered_associative.html
+     */
+    size_t operator()(const COutPoint& id) const noexcept {
+        return SipHashUint256Extra(k0, k1, id.hash, id.n);
+    }
+};
+
+struct FilterHeaderHasher
+{
+    size_t operator()(const uint256& hash) const { return ReadLE64(hash.begin()); }
+};
+
+/**
+ * We're hashing a nonce into the entries themselves, so we don't need extra
+ * blinding in the set hash computation.
+ *
+ * This may exhibit platform endian dependent behavior but because these are
+ * nonced hashes (random) and this state is only ever used locally it is safe.
+ * All that matters is local consistency.
+ */
+class SignatureCacheHasher
+{
+public:
+    template <uint8_t hash_select>
+    uint32_t operator()(const uint256& key) const
+    {
+        static_assert(hash_select <8, "SignatureCacheHasher only has 8 hashes available.");
+        uint32_t u;
+        std::memcpy(&u, key.begin()+4*hash_select, 4);
+        return u;
+    }
+};
+
+struct BlockHasher
+{
+    // this used to call `GetCheapHash()` in uint256, which was later moved; the
+    // cheap hash function simply calls ReadLE64() however, so the end result is
+    // identical
+    size_t operator()(const uint256& hash) const { return ReadLE64(hash.begin()); }
+};
+
+class SaltedSipHasher
+{
+private:
+    /** Salt */
+    const uint64_t m_k0, m_k1;
+
+public:
+    SaltedSipHasher();
+
+    size_t operator()(const Span<const unsigned char>& script) const;
+};
+
+#endif // DIGIBYTE_UTIL_HASHER_H

src/util/macros.h

@@ -0,0 +1,18 @@
+// Copyright (c) 2019 The DigiByte Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef DIGIBYTE_UTIL_MACROS_H
+#define DIGIBYTE_UTIL_MACROS_H
+
+#define PASTE(x, y) x ## y
+#define PASTE2(x, y) PASTE(x, y)
+
+/**
+ * Converts the parameter X to a string after macro replacement on X has been performed.
+ * Don't merge these into one macro!
+ */
+#define STRINGIZE(X) DO_STRINGIZE(X)
+#define DO_STRINGIZE(X) #X
+
+#endif // DIGIBYTE_UTIL_MACROS_H

src/util/message.cpp

@@ -0,0 +1,92 @@
+// Copyright (c) 2009-2010 Satoshi Nakamoto
+// Copyright (c) 2009-2020 The DigiByte Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include <hash.h>            // For CHashWriter
+#include <key.h>             // For CKey
+#include <key_io.h>          // For DecodeDestination()
+#include <pubkey.h>          // For CPubKey
+#include <script/standard.h> // For CTxDestination, IsValidDestination(), PKHash
+#include <serialize.h>       // For SER_GETHASH
+#include <util/message.h>
+#include <util/strencodings.h> // For DecodeBase64()
+
+#include <string>
+#include <vector>
+
+/**
+ * Text used to signify that a signed message follows and to prevent
+ * inadvertently signing a transaction.
+ */
+const std::string MESSAGE_MAGIC = "Vexta Signed Message:\n";
+
+MessageVerificationResult MessageVerify(
+    const std::string& address,
+    const std::string& signature,
+    const std::string& message)
+{
+    CTxDestination destination = DecodeDestination(address);
+    if (!IsValidDestination(destination)) {
+        return MessageVerificationResult::ERR_INVALID_ADDRESS;
+    }
+
+    if (std::get_if<PKHash>(&destination) == nullptr) {
+        return MessageVerificationResult::ERR_ADDRESS_NO_KEY;
+    }
+
+    bool invalid = false;
+    std::vector<unsigned char> signature_bytes = DecodeBase64(signature.c_str(), &invalid);
+    if (invalid) {
+        return MessageVerificationResult::ERR_MALFORMED_SIGNATURE;
+    }
+
+    CPubKey pubkey;
+    if (!pubkey.RecoverCompact(MessageHash(message), signature_bytes)) {
+        return MessageVerificationResult::ERR_PUBKEY_NOT_RECOVERED;
+    }
+
+    if (!(CTxDestination(PKHash(pubkey)) == destination)) {
+        return MessageVerificationResult::ERR_NOT_SIGNED;
+    }
+
+    return MessageVerificationResult::OK;
+}
+
+bool MessageSign(
+    const CKey& privkey,
+    const std::string& message,
+    std::string& signature)
+{
+    std::vector<unsigned char> signature_bytes;
+
+    if (!privkey.SignCompact(MessageHash(message), signature_bytes)) {
+        return false;
+    }
+
+    signature = EncodeBase64(signature_bytes);
+
+    return true;
+}
+
+uint256 MessageHash(const std::string& message)
+{
+    CHashWriter hasher(SER_GETHASH, 0);
+    hasher << MESSAGE_MAGIC << message;
+
+    return hasher.GetHash();
+}
+
+std::string SigningResultString(const SigningResult res)
+{
+    switch (res) {
+        case SigningResult::OK:
+            return "No error";
+        case SigningResult::PRIVATE_KEY_NOT_AVAILABLE:
+            return "Private key not available";
+        case SigningResult::SIGNING_FAILED:
+            return "Sign failed";
+        // no default case, so the compiler can warn about missing cases
+    }
+    assert(false);
+}

src/util/message.h

@@ -0,0 +1,76 @@
+// Copyright (c) 2009-2010 Satoshi Nakamoto
+// Copyright (c) 2009-2020 The DigiByte Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef DIGIBYTE_UTIL_MESSAGE_H
+#define DIGIBYTE_UTIL_MESSAGE_H
+
+#include <key.h> // For CKey
+#include <uint256.h>
+
+#include <string>
+
+extern const std::string MESSAGE_MAGIC;
+
+/** The result of a signed message verification.
+ * Message verification takes as an input:
+ * - address (with whose private key the message is supposed to have been signed)
+ * - signature
+ * - message
+ */
+enum class MessageVerificationResult {
+    //! The provided address is invalid.
+    ERR_INVALID_ADDRESS,
+
+    //! The provided address is valid but does not refer to a public key.
+    ERR_ADDRESS_NO_KEY,
+
+    //! The provided signature couldn't be parsed (maybe invalid base64).
+    ERR_MALFORMED_SIGNATURE,
+
+    //! A public key could not be recovered from the provided signature and message.
+    ERR_PUBKEY_NOT_RECOVERED,
+
+    //! The message was not signed with the private key of the provided address.
+    ERR_NOT_SIGNED,
+
+    //! The message verification was successful.
+    OK
+};
+
+enum class SigningResult {
+    OK, //!< No error
+    PRIVATE_KEY_NOT_AVAILABLE,
+    SIGNING_FAILED,
+};
+
+/** Verify a signed message.
+ * @param[in] address Signer's Vexta address, it must refer to a public key.
+ * @param[in] signature The signature in base64 format.
+ * @param[in] message The message that was signed.
+ * @return result code */
+MessageVerificationResult MessageVerify(
+    const std::string& address,
+    const std::string& signature,
+    const std::string& message);
+
+/** Sign a message.
+ * @param[in] privkey Private key to sign with.
+ * @param[in] message The message to sign.
+ * @param[out] signature Signature, base64 encoded, only set if true is returned.
+ * @return true if signing was successful. */
+bool MessageSign(
+    const CKey& privkey,
+    const std::string& message,
+    std::string& signature);
+
+/**
+ * Hashes a message for signing and verification in a manner that prevents
+ * inadvertently signing a transaction.
+ */
+uint256 MessageHash(const std::string& message);
+
+std::string SigningResultString(const SigningResult res);
+
+#endif // DIGIBYTE_UTIL_MESSAGE_H

src/util/moneystr.cpp

@@ -0,0 +1,83 @@
+// Copyright (c) 2009-2010 Satoshi Nakamoto
+// Copyright (c) 2009-2019 The Bitcoin Core developers
+// Copyright (c) 2014-2019 The DigiByte Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include <util/moneystr.h>
+
+#include <tinyformat.h>
+#include <util/strencodings.h>
+#include <util/string.h>
+
+std::string FormatMoney(const CAmount n)
+{
+    // Note: not using straight sprintf here because we do NOT want
+    // localized number formatting.
+    static_assert(COIN > 1);
+    int64_t quotient = n / COIN;
+    int64_t remainder = n % COIN;
+    if (n < 0) {
+        quotient = -quotient;
+        remainder = -remainder;
+    }
+    std::string str = strprintf("%d.%08d", quotient, remainder);
+
+    // Right-trim excess zeros before the decimal point:
+    int nTrim = 0;
+    for (int i = str.size()-1; (str[i] == '0' && IsDigit(str[i-2])); --i)
+        ++nTrim;
+    if (nTrim)
+        str.erase(str.size()-nTrim, nTrim);
+
+    if (n < 0)
+        str.insert((unsigned int)0, 1, '-');
+    return str;
+}
+
+
+bool ParseMoney(const std::string& money_string, CAmount& nRet)
+{
+    if (!ValidAsCString(money_string)) {
+        return false;
+    }
+    const std::string str = TrimString(money_string);
+    if (str.empty()) {
+        return false;
+    }
+
+    std::string strWhole;
+    int64_t nUnits = 0;
+    const char* p = str.c_str();
+    for (; *p; p++)
+    {
+        if (*p == '.')
+        {
+            p++;
+            int64_t nMult = COIN / 10;
+            while (IsDigit(*p) && (nMult > 0))
+            {
+                nUnits += nMult * (*p++ - '0');
+                nMult /= 10;
+            }
+            break;
+        }
+        if (IsSpace(*p))
+            return false;
+        if (!IsDigit(*p))
+            return false;
+        strWhole.insert(strWhole.end(), *p);
+    }
+    if (*p) {
+        return false;
+    }
+    if (strWhole.size() > 10) // guard against 63 bit overflow
+        return false;
+    if (nUnits < 0 || nUnits > COIN)
+        return false;
+    int64_t nWhole = atoi64(strWhole);
+    CAmount nValue = nWhole*COIN + nUnits;
+
+    nRet = nValue;
+    return true;
+}

src/util/moneystr.h

@@ -0,0 +1,25 @@
+// Copyright (c) 2009-2010 Satoshi Nakamoto
+// Copyright (c) 2009-2019 The Bitcoin Core developers
+// Copyright (c) 2014-2019 The DigiByte Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+/**
+ * Money parsing/formatting utilities.
+ */
+#ifndef DIGIBYTE_UTIL_MONEYSTR_H
+#define DIGIBYTE_UTIL_MONEYSTR_H
+
+#include <amount.h>
+#include <attributes.h>
+
+#include <string>
+
+/* Do not use these functions to represent or parse monetary amounts to or from
+ * JSON but use AmountFromValue and ValueFromAmount for that.
+ */
+std::string FormatMoney(const CAmount n);
+/** Parse an amount denoted in full coins. E.g. "0.0034" supplied on the command line. **/
+[[nodiscard]] bool ParseMoney(const std::string& str, CAmount& nRet);
+
+#endif // DIGIBYTE_UTIL_MONEYSTR_H

src/util/rbf.cpp

@@ -0,0 +1,17 @@
+// Copyright (c) 2016-2019 The DigiByte Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include <util/rbf.h>
+
+#include <primitives/transaction.h>
+
+bool SignalsOptInRBF(const CTransaction &tx)
+{
+    for (const CTxIn &txin : tx.vin) {
+        if (txin.nSequence <= MAX_BIP125_RBF_SEQUENCE) {
+            return true;
+        }
+    }
+    return false;
+}

src/util/rbf.h

@@ -0,0 +1,18 @@
+// Copyright (c) 2016-2019 The DigiByte Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef DIGIBYTE_UTIL_RBF_H
+#define DIGIBYTE_UTIL_RBF_H
+
+#include <cstdint>
+
+class CTransaction;
+
+static const uint32_t MAX_BIP125_RBF_SEQUENCE = 0xfffffffd;
+
+// Check whether the sequence numbers on this transaction are signaling
+// opt-in to replace-by-fee, according to BIP 125
+bool SignalsOptInRBF(const CTransaction &tx);
+
+#endif // DIGIBYTE_UTIL_RBF_H

src/util/readwritefile.cpp

@@ -0,0 +1,47 @@
+// Copyright (c) 2015-2020 The DigiByte Core developers
+// Copyright (c) 2017 The Zcash developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include <fs.h>
+
+#include <limits>
+#include <stdio.h>
+#include <string>
+#include <utility>
+
+std::pair<bool,std::string> ReadBinaryFile(const fs::path &filename, size_t maxsize=std::numeric_limits<size_t>::max())
+{
+    FILE *f = fsbridge::fopen(filename, "rb");
+    if (f == nullptr)
+        return std::make_pair(false,"");
+    std::string retval;
+    char buffer[128];
+    do {
+        const size_t n = fread(buffer, 1, sizeof(buffer), f);
+        // Check for reading errors so we don't return any data if we couldn't
+        // read the entire file (or up to maxsize)
+        if (ferror(f)) {
+            fclose(f);
+            return std::make_pair(false,"");
+        }
+        retval.append(buffer, buffer+n);
+    } while (!feof(f) && retval.size() <= maxsize);
+    fclose(f);
+    return std::make_pair(true,retval);
+}
+
+bool WriteBinaryFile(const fs::path &filename, const std::string &data)
+{
+    FILE *f = fsbridge::fopen(filename, "wb");
+    if (f == nullptr)
+        return false;
+    if (fwrite(data.data(), 1, data.size(), f) != data.size()) {
+        fclose(f);
+        return false;
+    }
+    if (fclose(f) != 0) {
+        return false;
+    }
+    return true;
+}

src/util/readwritefile.h

@@ -0,0 +1,28 @@
+// Copyright (c) 2015-2020 The DigiByte Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef DIGIBYTE_UTIL_READWRITEFILE_H
+#define DIGIBYTE_UTIL_READWRITEFILE_H
+
+#include <fs.h>
+
+#include <limits>
+#include <string>
+#include <utility>
+
+/** Read full contents of a file and return them in a std::string.
+ * Returns a pair <status, string>.
+ * If an error occurred, status will be false, otherwise status will be true and the data will be returned in string.
+ *
+ * @param maxsize Puts a maximum size limit on the file that is read. If the file is larger than this, truncated data
+ *         (with len > maxsize) will be returned.
+ */
+std::pair<bool,std::string> ReadBinaryFile(const fs::path &filename, size_t maxsize=std::numeric_limits<size_t>::max());
+
+/** Write contents of std::string to a file.
+ * @return true on success.
+ */
+bool WriteBinaryFile(const fs::path &filename, const std::string &data);
+
+#endif /* DIGIBYTE_UTIL_READWRITEFILE_H */

src/util/serfloat.cpp

@@ -0,0 +1,64 @@
+// Copyright (c) 2021 The DigiByte Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include <util/serfloat.h>
+
+#include <cmath>
+#include <limits>
+
+double DecodeDouble(uint64_t v) noexcept {
+    static constexpr double NANVAL = std::numeric_limits<double>::quiet_NaN();
+    static constexpr double INFVAL = std::numeric_limits<double>::infinity();
+    double sign = 1.0;
+    if (v & 0x8000000000000000) {
+        sign = -1.0;
+        v ^= 0x8000000000000000;
+    }
+    // Zero
+    if (v == 0) return copysign(0.0, sign);
+    // Infinity
+    if (v == 0x7ff0000000000000) return copysign(INFVAL, sign);
+    // Other numbers
+    int exp = (v & 0x7FF0000000000000) >> 52;
+    uint64_t man = v & 0xFFFFFFFFFFFFF;
+    if (exp == 2047) {
+        // NaN
+        return NANVAL;
+    } else if (exp == 0) {
+        // Subnormal
+        return copysign(ldexp((double)man, -1074), sign);
+    } else {
+        // Normal
+        return copysign(ldexp((double)(man + 0x10000000000000), -1075 + exp), sign);
+    }
+}
+
+uint64_t EncodeDouble(double f) noexcept {
+    int cls = std::fpclassify(f);
+    uint64_t sign = 0;
+    if (copysign(1.0, f) == -1.0) {
+        f = -f;
+        sign = 0x8000000000000000;
+    }
+    // Zero
+    if (cls == FP_ZERO) return sign;
+    // Infinity
+    if (cls == FP_INFINITE) return sign | 0x7ff0000000000000;
+    // NaN
+    if (cls == FP_NAN) return 0x7ff8000000000000;
+    // Other numbers
+    int exp;
+    uint64_t man = std::round(std::frexp(f, &exp) * 9007199254740992.0);
+    if (exp < -1021) {
+        // Too small to represent, encode 0
+        if (exp < -1084) return sign;
+        // Subnormal numbers
+        return sign | (man >> (-1021 - exp));
+    } else {
+        // Too big to represent, encode infinity
+        if (exp > 1024) return sign | 0x7ff0000000000000;
+        // Normal numbers
+        return sign | (((uint64_t)(1022 + exp)) << 52) | (man & 0xFFFFFFFFFFFFF);
+    }
+}

src/util/serfloat.h

@@ -0,0 +1,16 @@
+// Copyright (c) 2021 The DigiByte Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef DIGIBYTE_UTIL_SERFLOAT_H
+#define DIGIBYTE_UTIL_SERFLOAT_H
+
+#include <stdint.h>
+
+/* Encode a double using the IEEE 754 binary64 format. All NaNs are encoded as x86/ARM's
+ * positive quiet NaN with payload 0. */
+uint64_t EncodeDouble(double f) noexcept;
+/* Reverse operation of DecodeDouble. DecodeDouble(EncodeDouble(f))==f unless isnan(f). */
+double DecodeDouble(uint64_t v) noexcept;
+
+#endif // DIGIBYTE_UTIL_SERFLOAT_H

src/util/settings.cpp

@@ -0,0 +1,240 @@
+// Copyright (c) 2019 The DigiByte Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include <util/settings.h>
+
+#include <tinyformat.h>
+#include <univalue.h>
+
+namespace util {
+namespace {
+
+enum class Source {
+   FORCED,
+   COMMAND_LINE,
+   RW_SETTINGS,
+   CONFIG_FILE_NETWORK_SECTION,
+   CONFIG_FILE_DEFAULT_SECTION
+};
+
+//! Merge settings from multiple sources in precedence order:
+//! Forced config > command line > read-write settings file > config file network-specific section > config file default section
+//!
+//! This function is provided with a callback function fn that contains
+//! specific logic for how to merge the sources.
+template <typename Fn>
+static void MergeSettings(const Settings& settings, const std::string& section, const std::string& name, Fn&& fn)
+{
+    // Merge in the forced settings
+    if (auto* value = FindKey(settings.forced_settings, name)) {
+        fn(SettingsSpan(*value), Source::FORCED);
+    }
+    // Merge in the command-line options
+    if (auto* values = FindKey(settings.command_line_options, name)) {
+        fn(SettingsSpan(*values), Source::COMMAND_LINE);
+    }
+    // Merge in the read-write settings
+    if (const SettingsValue* value = FindKey(settings.rw_settings, name)) {
+        fn(SettingsSpan(*value), Source::RW_SETTINGS);
+    }
+    // Merge in the network-specific section of the config file
+    if (!section.empty()) {
+        if (auto* map = FindKey(settings.ro_config, section)) {
+            if (auto* values = FindKey(*map, name)) {
+                fn(SettingsSpan(*values), Source::CONFIG_FILE_NETWORK_SECTION);
+            }
+        }
+    }
+    // Merge in the default section of the config file
+    if (auto* map = FindKey(settings.ro_config, "")) {
+        if (auto* values = FindKey(*map, name)) {
+            fn(SettingsSpan(*values), Source::CONFIG_FILE_DEFAULT_SECTION);
+        }
+    }
+}
+} // namespace
+
+bool ReadSettings(const fs::path& path, std::map<std::string, SettingsValue>& values, std::vector<std::string>& errors)
+{
+    values.clear();
+    errors.clear();
+
+    fsbridge::ifstream file;
+    file.open(path);
+    if (!file.is_open()) return true; // Ok for file not to exist.
+
+    SettingsValue in;
+    if (!in.read(std::string{std::istreambuf_iterator<char>(file), std::istreambuf_iterator<char>()})) {
+        errors.emplace_back(strprintf("Unable to parse settings file %s", path.string()));
+        return false;
+    }
+
+    if (file.fail()) {
+        errors.emplace_back(strprintf("Failed reading settings file %s", path.string()));
+        return false;
+    }
+    file.close(); // Done with file descriptor. Release while copying data.
+
+    if (!in.isObject()) {
+        errors.emplace_back(strprintf("Found non-object value %s in settings file %s", in.write(), path.string()));
+        return false;
+    }
+
+    const std::vector<std::string>& in_keys = in.getKeys();
+    const std::vector<SettingsValue>& in_values = in.getValues();
+    for (size_t i = 0; i < in_keys.size(); ++i) {
+        auto inserted = values.emplace(in_keys[i], in_values[i]);
+        if (!inserted.second) {
+            errors.emplace_back(strprintf("Found duplicate key %s in settings file %s", in_keys[i], path.string()));
+        }
+    }
+    return errors.empty();
+}
+
+bool WriteSettings(const fs::path& path,
+    const std::map<std::string, SettingsValue>& values,
+    std::vector<std::string>& errors)
+{
+    SettingsValue out(SettingsValue::VOBJ);
+    for (const auto& value : values) {
+        out.__pushKV(value.first, value.second);
+    }
+    fsbridge::ofstream file;
+    file.open(path);
+    if (file.fail()) {
+        errors.emplace_back(strprintf("Error: Unable to open settings file %s for writing", path.string()));
+        return false;
+    }
+    file << out.write(/* prettyIndent= */ 1, /* indentLevel= */ 4) << std::endl;
+    file.close();
+    return true;
+}
+
+SettingsValue GetSetting(const Settings& settings,
+    const std::string& section,
+    const std::string& name,
+    bool ignore_default_section_config,
+    bool get_chain_name)
+{
+    SettingsValue result;
+    bool done = false; // Done merging any more settings sources.
+    MergeSettings(settings, section, name, [&](SettingsSpan span, Source source) {
+        // Weird behavior preserved for backwards compatibility: Apply negated
+        // setting even if non-negated setting would be ignored. A negated
+        // value in the default section is applied to network specific options,
+        // even though normal non-negated values there would be ignored.
+        const bool never_ignore_negated_setting = span.last_negated();
+
+        // Weird behavior preserved for backwards compatibility: Take first
+        // assigned value instead of last. In general, later settings take
+        // precedence over early settings, but for backwards compatibility in
+        // the config file the precedence is reversed for all settings except
+        // chain name settings.
+        const bool reverse_precedence =
+            (source == Source::CONFIG_FILE_NETWORK_SECTION || source == Source::CONFIG_FILE_DEFAULT_SECTION) &&
+            !get_chain_name;
+
+        // Weird behavior preserved for backwards compatibility: Negated
+        // -regtest and -testnet arguments which you would expect to override
+        // values set in the configuration file are currently accepted but
+        // silently ignored. It would be better to apply these just like other
+        // negated values, or at least warn they are ignored.
+        const bool skip_negated_command_line = get_chain_name;
+
+        if (done) return;
+
+        // Ignore settings in default config section if requested.
+        if (ignore_default_section_config && source == Source::CONFIG_FILE_DEFAULT_SECTION &&
+            !never_ignore_negated_setting) {
+            return;
+        }
+
+        // Skip negated command line settings.
+        if (skip_negated_command_line && span.last_negated()) return;
+
+        if (!span.empty()) {
+            result = reverse_precedence ? span.begin()[0] : span.end()[-1];
+            done = true;
+        } else if (span.last_negated()) {
+            result = false;
+            done = true;
+        }
+    });
+    return result;
+}
+
+std::vector<SettingsValue> GetSettingsList(const Settings& settings,
+    const std::string& section,
+    const std::string& name,
+    bool ignore_default_section_config)
+{
+    std::vector<SettingsValue> result;
+    bool done = false; // Done merging any more settings sources.
+    bool prev_negated_empty = false;
+    MergeSettings(settings, section, name, [&](SettingsSpan span, Source source) {
+        // Weird behavior preserved for backwards compatibility: Apply config
+        // file settings even if negated on command line. Negating a setting on
+        // command line will ignore earlier settings on the command line and
+        // ignore settings in the config file, unless the negated command line
+        // value is followed by non-negated value, in which case config file
+        // settings will be brought back from the dead (but earlier command
+        // line settings will still be ignored).
+        const bool add_zombie_config_values =
+            (source == Source::CONFIG_FILE_NETWORK_SECTION || source == Source::CONFIG_FILE_DEFAULT_SECTION) &&
+            !prev_negated_empty;
+
+        // Ignore settings in default config section if requested.
+        if (ignore_default_section_config && source == Source::CONFIG_FILE_DEFAULT_SECTION) return;
+
+        // Add new settings to the result if isn't already complete, or if the
+        // values are zombies.
+        if (!done || add_zombie_config_values) {
+            for (const auto& value : span) {
+                if (value.isArray()) {
+                    result.insert(result.end(), value.getValues().begin(), value.getValues().end());
+                } else {
+                    result.push_back(value);
+                }
+            }
+        }
+
+        // If a setting was negated, or if a setting was forced, set
+        // done to true to ignore any later lower priority settings.
+        done |= span.negated() > 0 || source == Source::FORCED;
+
+        // Update the negated and empty state used for the zombie values check.
+        prev_negated_empty |= span.last_negated() && result.empty();
+    });
+    return result;
+}
+
+bool OnlyHasDefaultSectionSetting(const Settings& settings, const std::string& section, const std::string& name)
+{
+    bool has_default_section_setting = false;
+    bool has_other_setting = false;
+    MergeSettings(settings, section, name, [&](SettingsSpan span, Source source) {
+        if (span.empty()) return;
+        else if (source == Source::CONFIG_FILE_DEFAULT_SECTION) has_default_section_setting = true;
+        else has_other_setting = true;
+    });
+    // If a value is set in the default section and not explicitly overwritten by the
+    // user on the command line or in a different section, then we want to enable
+    // warnings about the value being ignored.
+    return has_default_section_setting && !has_other_setting;
+}
+
+SettingsSpan::SettingsSpan(const std::vector<SettingsValue>& vec) noexcept : SettingsSpan(vec.data(), vec.size()) {}
+const SettingsValue* SettingsSpan::begin() const { return data + negated(); }
+const SettingsValue* SettingsSpan::end() const { return data + size; }
+bool SettingsSpan::empty() const { return size == 0 || last_negated(); }
+bool SettingsSpan::last_negated() const { return size > 0 && data[size - 1].isFalse(); }
+size_t SettingsSpan::negated() const
+{
+    for (size_t i = size; i > 0; --i) {
+        if (data[i - 1].isFalse()) return i; // Return number of negated values (position of last false value)
+    }
+    return 0;
+}
+
+} // namespace util

src/util/settings.h

@@ -0,0 +1,108 @@
+// Copyright (c) 2019-2020 The DigiByte Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef DIGIBYTE_UTIL_SETTINGS_H
+#define DIGIBYTE_UTIL_SETTINGS_H
+
+#include <fs.h>
+
+#include <map>
+#include <string>
+#include <vector>
+
+class UniValue;
+
+namespace util {
+
+//! Settings value type (string/integer/boolean/null variant).
+//!
+//! @note UniValue is used here for convenience and because it can be easily
+//!       serialized in a readable format. But any other variant type that can
+//!       be assigned strings, int64_t, and bool values and has get_str(),
+//!       get_int64(), get_bool(), isNum(), isBool(), isFalse(), isTrue() and
+//!       isNull() methods can be substituted if there's a need to move away
+//!       from UniValue. (An implementation with boost::variant was posted at
+//!       https://github.com/digibyte/digibyte/pull/15934/files#r337691812)
+using SettingsValue = UniValue;
+
+//! Stored settings. This struct combines settings from the command line, a
+//! read-only configuration file, and a read-write runtime settings file.
+struct Settings {
+    //! Map of setting name to forced setting value.
+    std::map<std::string, SettingsValue> forced_settings;
+    //! Map of setting name to list of command line values.
+    std::map<std::string, std::vector<SettingsValue>> command_line_options;
+    //! Map of setting name to read-write file setting value.
+    std::map<std::string, SettingsValue> rw_settings;
+    //! Map of config section name and setting name to list of config file values.
+    std::map<std::string, std::map<std::string, std::vector<SettingsValue>>> ro_config;
+};
+
+//! Read settings file.
+bool ReadSettings(const fs::path& path,
+    std::map<std::string, SettingsValue>& values,
+    std::vector<std::string>& errors);
+
+//! Write settings file.
+bool WriteSettings(const fs::path& path,
+    const std::map<std::string, SettingsValue>& values,
+    std::vector<std::string>& errors);
+
+//! Get settings value from combined sources: forced settings, command line
+//! arguments, runtime read-write settings, and the read-only config file.
+//!
+//! @param ignore_default_section_config - ignore values in the default section
+//!                                        of the config file (part before any
+//!                                        [section] keywords)
+//! @param get_chain_name - enable special backwards compatible behavior
+//!                         for GetChainName
+SettingsValue GetSetting(const Settings& settings,
+    const std::string& section,
+    const std::string& name,
+    bool ignore_default_section_config,
+    bool get_chain_name);
+
+//! Get combined setting value similar to GetSetting(), except if setting was
+//! specified multiple times, return a list of all the values specified.
+std::vector<SettingsValue> GetSettingsList(const Settings& settings,
+    const std::string& section,
+    const std::string& name,
+    bool ignore_default_section_config);
+
+//! Return true if a setting is set in the default config file section, and not
+//! overridden by a higher priority command-line or network section value.
+//!
+//! This is used to provide user warnings about values that might be getting
+//! ignored unintentionally.
+bool OnlyHasDefaultSectionSetting(const Settings& settings, const std::string& section, const std::string& name);
+
+//! Accessor for list of settings that skips negated values when iterated over.
+//! The last boolean `false` value in the list and all earlier values are
+//! considered negated.
+struct SettingsSpan {
+    explicit SettingsSpan() = default;
+    explicit SettingsSpan(const SettingsValue& value) noexcept : SettingsSpan(&value, 1) {}
+    explicit SettingsSpan(const SettingsValue* data, size_t size) noexcept : data(data), size(size) {}
+    explicit SettingsSpan(const std::vector<SettingsValue>& vec) noexcept;
+    const SettingsValue* begin() const; //!< Pointer to first non-negated value.
+    const SettingsValue* end() const;   //!< Pointer to end of values.
+    bool empty() const;                 //!< True if there are any non-negated values.
+    bool last_negated() const;          //!< True if the last value is negated.
+    size_t negated() const;             //!< Number of negated values.
+
+    const SettingsValue* data = nullptr;
+    size_t size = 0;
+};
+
+//! Map lookup helper.
+template <typename Map, typename Key>
+auto FindKey(Map&& map, Key&& key) -> decltype(&map.at(key))
+{
+    auto it = map.find(key);
+    return it == map.end() ? nullptr : &it->second;
+}
+
+} // namespace util
+
+#endif // DIGIBYTE_UTIL_SETTINGS_H

src/util/sock.cpp

@@ -0,0 +1,343 @@
+// Copyright (c) 2020-2021 The DigiByte Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include <compat.h>
+#include <logging.h>
+#include <threadinterrupt.h>
+#include <tinyformat.h>
+#include <util/sock.h>
+#include <util/system.h>
+#include <util/time.h>
+
+#include <codecvt>
+#include <cwchar>
+#include <locale>
+#include <stdexcept>
+#include <string>
+
+#ifdef USE_POLL
+#include <poll.h>
+#endif
+
+static inline bool IOErrorIsPermanent(int err)
+{
+    return err != WSAEAGAIN && err != WSAEINTR && err != WSAEWOULDBLOCK && err != WSAEINPROGRESS;
+}
+
+Sock::Sock() : m_socket(INVALID_SOCKET) {}
+
+Sock::Sock(SOCKET s) : m_socket(s) {}
+
+Sock::Sock(Sock&& other)
+{
+    m_socket = other.m_socket;
+    other.m_socket = INVALID_SOCKET;
+}
+
+Sock::~Sock() { Reset(); }
+
+Sock& Sock::operator=(Sock&& other)
+{
+    Reset();
+    m_socket = other.m_socket;
+    other.m_socket = INVALID_SOCKET;
+    return *this;
+}
+
+SOCKET Sock::Get() const { return m_socket; }
+
+SOCKET Sock::Release()
+{
+    const SOCKET s = m_socket;
+    m_socket = INVALID_SOCKET;
+    return s;
+}
+
+void Sock::Reset() { CloseSocket(m_socket); }
+
+ssize_t Sock::Send(const void* data, size_t len, int flags) const
+{
+    return send(m_socket, static_cast<const char*>(data), len, flags);
+}
+
+ssize_t Sock::Recv(void* buf, size_t len, int flags) const
+{
+    return recv(m_socket, static_cast<char*>(buf), len, flags);
+}
+
+int Sock::Connect(const sockaddr* addr, socklen_t addr_len) const
+{
+    return connect(m_socket, addr, addr_len);
+}
+
+int Sock::GetSockOpt(int level, int opt_name, void* opt_val, socklen_t* opt_len) const
+{
+    return getsockopt(m_socket, level, opt_name, static_cast<char*>(opt_val), opt_len);
+}
+
+bool Sock::Wait(std::chrono::milliseconds timeout, Event requested, Event* occurred) const
+{
+#ifdef USE_POLL
+    pollfd fd;
+    fd.fd = m_socket;
+    fd.events = 0;
+    if (requested & RECV) {
+        fd.events |= POLLIN;
+    }
+    if (requested & SEND) {
+        fd.events |= POLLOUT;
+    }
+
+    if (poll(&fd, 1, count_milliseconds(timeout)) == SOCKET_ERROR) {
+        return false;
+    }
+
+    if (occurred != nullptr) {
+        *occurred = 0;
+        if (fd.revents & POLLIN) {
+            *occurred |= RECV;
+        }
+        if (fd.revents & POLLOUT) {
+            *occurred |= SEND;
+        }
+    }
+
+    return true;
+#else
+    if (!IsSelectableSocket(m_socket)) {
+        return false;
+    }
+
+    fd_set fdset_recv;
+    fd_set fdset_send;
+    FD_ZERO(&fdset_recv);
+    FD_ZERO(&fdset_send);
+
+    if (requested & RECV) {
+        FD_SET(m_socket, &fdset_recv);
+    }
+
+    if (requested & SEND) {
+        FD_SET(m_socket, &fdset_send);
+    }
+
+    timeval timeout_struct = MillisToTimeval(timeout);
+
+    if (select(m_socket + 1, &fdset_recv, &fdset_send, nullptr, &timeout_struct) == SOCKET_ERROR) {
+        return false;
+    }
+
+    if (occurred != nullptr) {
+        *occurred = 0;
+        if (FD_ISSET(m_socket, &fdset_recv)) {
+            *occurred |= RECV;
+        }
+        if (FD_ISSET(m_socket, &fdset_send)) {
+            *occurred |= SEND;
+        }
+    }
+
+    return true;
+#endif /* USE_POLL */
+}
+
+void Sock::SendComplete(const std::string& data,
+                        std::chrono::milliseconds timeout,
+                        CThreadInterrupt& interrupt) const
+{
+    const auto deadline = GetTime<std::chrono::milliseconds>() + timeout;
+    size_t sent{0};
+
+    for (;;) {
+        const ssize_t ret{Send(data.data() + sent, data.size() - sent, MSG_NOSIGNAL)};
+
+        if (ret > 0) {
+            sent += static_cast<size_t>(ret);
+            if (sent == data.size()) {
+                break;
+            }
+        } else {
+            const int err{WSAGetLastError()};
+            if (IOErrorIsPermanent(err)) {
+                throw std::runtime_error(strprintf("send(): %s", NetworkErrorString(err)));
+            }
+        }
+
+        const auto now = GetTime<std::chrono::milliseconds>();
+
+        if (now >= deadline) {
+            throw std::runtime_error(strprintf(
+                "Send timeout (sent only %u of %u bytes before that)", sent, data.size()));
+        }
+
+        if (interrupt) {
+            throw std::runtime_error(strprintf(
+                "Send interrupted (sent only %u of %u bytes before that)", sent, data.size()));
+        }
+
+        // Wait for a short while (or the socket to become ready for sending) before retrying
+        // if nothing was sent.
+        const auto wait_time = std::min(deadline - now, std::chrono::milliseconds{MAX_WAIT_FOR_IO});
+        (void)Wait(wait_time, SEND);
+    }
+}
+
+std::string Sock::RecvUntilTerminator(uint8_t terminator,
+                                      std::chrono::milliseconds timeout,
+                                      CThreadInterrupt& interrupt,
+                                      size_t max_data) const
+{
+    const auto deadline = GetTime<std::chrono::milliseconds>() + timeout;
+    std::string data;
+    bool terminator_found{false};
+
+    // We must not consume any bytes past the terminator from the socket.
+    // One option is to read one byte at a time and check if we have read a terminator.
+    // However that is very slow. Instead, we peek at what is in the socket and only read
+    // as many bytes as possible without crossing the terminator.
+    // Reading 64 MiB of random data with 262526 terminator chars takes 37 seconds to read
+    // one byte at a time VS 0.71 seconds with the "peek" solution below. Reading one byte
+    // at a time is about 50 times slower.
+
+    for (;;) {
+        if (data.size() >= max_data) {
+            throw std::runtime_error(
+                strprintf("Received too many bytes without a terminator (%u)", data.size()));
+        }
+
+        char buf[512];
+
+        const ssize_t peek_ret{Recv(buf, std::min(sizeof(buf), max_data - data.size()), MSG_PEEK)};
+
+        switch (peek_ret) {
+        case -1: {
+            const int err{WSAGetLastError()};
+            if (IOErrorIsPermanent(err)) {
+                throw std::runtime_error(strprintf("recv(): %s", NetworkErrorString(err)));
+            }
+            break;
+        }
+        case 0:
+            throw std::runtime_error("Connection unexpectedly closed by peer");
+        default:
+            auto end = buf + peek_ret;
+            auto terminator_pos = std::find(buf, end, terminator);
+            terminator_found = terminator_pos != end;
+
+            const size_t try_len{terminator_found ? terminator_pos - buf + 1 :
+                                                    static_cast<size_t>(peek_ret)};
+
+            const ssize_t read_ret{Recv(buf, try_len, 0)};
+
+            if (read_ret < 0 || static_cast<size_t>(read_ret) != try_len) {
+                throw std::runtime_error(
+                    strprintf("recv() returned %u bytes on attempt to read %u bytes but previous "
+                              "peek claimed %u bytes are available",
+                              read_ret, try_len, peek_ret));
+            }
+
+            // Don't include the terminator in the output.
+            const size_t append_len{terminator_found ? try_len - 1 : try_len};
+
+            data.append(buf, buf + append_len);
+
+            if (terminator_found) {
+                return data;
+            }
+        }
+
+        const auto now = GetTime<std::chrono::milliseconds>();
+
+        if (now >= deadline) {
+            throw std::runtime_error(strprintf(
+                "Receive timeout (received %u bytes without terminator before that)", data.size()));
+        }
+
+        if (interrupt) {
+            throw std::runtime_error(strprintf(
+                "Receive interrupted (received %u bytes without terminator before that)",
+                data.size()));
+        }
+
+        // Wait for a short while (or the socket to become ready for reading) before retrying.
+        const auto wait_time = std::min(deadline - now, std::chrono::milliseconds{MAX_WAIT_FOR_IO});
+        (void)Wait(wait_time, RECV);
+    }
+}
+
+bool Sock::IsConnected(std::string& errmsg) const
+{
+    if (m_socket == INVALID_SOCKET) {
+        errmsg = "not connected";
+        return false;
+    }
+
+    char c;
+    switch (Recv(&c, sizeof(c), MSG_PEEK)) {
+    case -1: {
+        const int err = WSAGetLastError();
+        if (IOErrorIsPermanent(err)) {
+            errmsg = NetworkErrorString(err);
+            return false;
+        }
+        return true;
+    }
+    case 0:
+        errmsg = "closed";
+        return false;
+    default:
+        return true;
+    }
+}
+
+#ifdef WIN32
+std::string NetworkErrorString(int err)
+{
+    wchar_t buf[256];
+    buf[0] = 0;
+    if(FormatMessageW(FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS | FORMAT_MESSAGE_MAX_WIDTH_MASK,
+            nullptr, err, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
+            buf, ARRAYSIZE(buf), nullptr))
+    {
+        return strprintf("%s (%d)", std::wstring_convert<std::codecvt_utf8_utf16<wchar_t>,wchar_t>().to_bytes(buf), err);
+    }
+    else
+    {
+        return strprintf("Unknown error (%d)", err);
+    }
+}
+#else
+std::string NetworkErrorString(int err)
+{
+    char buf[256];
+    buf[0] = 0;
+    /* Too bad there are two incompatible implementations of the
+     * thread-safe strerror. */
+    const char *s;
+#ifdef STRERROR_R_CHAR_P /* GNU variant can return a pointer outside the passed buffer */
+    s = strerror_r(err, buf, sizeof(buf));
+#else /* POSIX variant always returns message in buffer */
+    s = buf;
+    if (strerror_r(err, buf, sizeof(buf)))
+        buf[0] = 0;
+#endif
+    return strprintf("%s (%d)", s, err);
+}
+#endif
+
+bool CloseSocket(SOCKET& hSocket)
+{
+    if (hSocket == INVALID_SOCKET)
+        return false;
+#ifdef WIN32
+    int ret = closesocket(hSocket);
+#else
+    int ret = close(hSocket);
+#endif
+    if (ret) {
+        LogPrintf("Socket close failed: %d. Error: %s\n", hSocket, NetworkErrorString(WSAGetLastError()));
+    }
+    hSocket = INVALID_SOCKET;
+    return ret != SOCKET_ERROR;
+}

src/util/sock.h

@@ -0,0 +1,185 @@
+// Copyright (c) 2020-2021 The DigiByte Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef DIGIBYTE_UTIL_SOCK_H
+#define DIGIBYTE_UTIL_SOCK_H
+
+#include <compat.h>
+#include <threadinterrupt.h>
+#include <util/time.h>
+
+#include <chrono>
+#include <string>
+
+/**
+ * Maximum time to wait for I/O readiness.
+ * It will take up until this time to break off in case of an interruption.
+ */
+static constexpr auto MAX_WAIT_FOR_IO = 1s;
+
+/**
+ * RAII helper class that manages a socket. Mimics `std::unique_ptr`, but instead of a pointer it
+ * contains a socket and closes it automatically when it goes out of scope.
+ */
+class Sock
+{
+public:
+    /**
+     * Default constructor, creates an empty object that does nothing when destroyed.
+     */
+    Sock();
+
+    /**
+     * Take ownership of an existent socket.
+     */
+    explicit Sock(SOCKET s);
+
+    /**
+     * Copy constructor, disabled because closing the same socket twice is undesirable.
+     */
+    Sock(const Sock&) = delete;
+
+    /**
+     * Move constructor, grab the socket from another object and close ours (if set).
+     */
+    Sock(Sock&& other);
+
+    /**
+     * Destructor, close the socket or do nothing if empty.
+     */
+    virtual ~Sock();
+
+    /**
+     * Copy assignment operator, disabled because closing the same socket twice is undesirable.
+     */
+    Sock& operator=(const Sock&) = delete;
+
+    /**
+     * Move assignment operator, grab the socket from another object and close ours (if set).
+     */
+    virtual Sock& operator=(Sock&& other);
+
+    /**
+     * Get the value of the contained socket.
+     * @return socket or INVALID_SOCKET if empty
+     */
+    [[nodiscard]] virtual SOCKET Get() const;
+
+    /**
+     * Get the value of the contained socket and drop ownership. It will not be closed by the
+     * destructor after this call.
+     * @return socket or INVALID_SOCKET if empty
+     */
+    virtual SOCKET Release();
+
+    /**
+     * Close if non-empty.
+     */
+    virtual void Reset();
+
+    /**
+     * send(2) wrapper. Equivalent to `send(this->Get(), data, len, flags);`. Code that uses this
+     * wrapper can be unit tested if this method is overridden by a mock Sock implementation.
+     */
+    [[nodiscard]] virtual ssize_t Send(const void* data, size_t len, int flags) const;
+
+    /**
+     * recv(2) wrapper. Equivalent to `recv(this->Get(), buf, len, flags);`. Code that uses this
+     * wrapper can be unit tested if this method is overridden by a mock Sock implementation.
+     */
+    [[nodiscard]] virtual ssize_t Recv(void* buf, size_t len, int flags) const;
+
+    /**
+     * connect(2) wrapper. Equivalent to `connect(this->Get(), addr, addrlen)`. Code that uses this
+     * wrapper can be unit tested if this method is overridden by a mock Sock implementation.
+     */
+    [[nodiscard]] virtual int Connect(const sockaddr* addr, socklen_t addr_len) const;
+
+    /**
+     * getsockopt(2) wrapper. Equivalent to
+     * `getsockopt(this->Get(), level, opt_name, opt_val, opt_len)`. Code that uses this
+     * wrapper can be unit tested if this method is overridden by a mock Sock implementation.
+     */
+    [[nodiscard]] virtual int GetSockOpt(int level,
+                                         int opt_name,
+                                         void* opt_val,
+                                         socklen_t* opt_len) const;
+
+    using Event = uint8_t;
+
+    /**
+     * If passed to `Wait()`, then it will wait for readiness to read from the socket.
+     */
+    static constexpr Event RECV = 0b01;
+
+    /**
+     * If passed to `Wait()`, then it will wait for readiness to send to the socket.
+     */
+    static constexpr Event SEND = 0b10;
+
+    /**
+     * Wait for readiness for input (recv) or output (send).
+     * @param[in] timeout Wait this much for at least one of the requested events to occur.
+     * @param[in] requested Wait for those events, bitwise-or of `RECV` and `SEND`.
+     * @param[out] occurred If not nullptr and `true` is returned, then upon return this
+     * indicates which of the requested events occurred. A timeout is indicated by return
+     * value of `true` and `occurred` being set to 0.
+     * @return true on success and false otherwise
+     */
+    [[nodiscard]] virtual bool Wait(std::chrono::milliseconds timeout,
+                                    Event requested,
+                                    Event* occurred = nullptr) const;
+
+    /* Higher level, convenience, methods. These may throw. */
+
+    /**
+     * Send the given data, retrying on transient errors.
+     * @param[in] data Data to send.
+     * @param[in] timeout Timeout for the entire operation.
+     * @param[in] interrupt If this is signaled then the operation is canceled.
+     * @throws std::runtime_error if the operation cannot be completed. In this case only some of
+     * the data will be written to the socket.
+     */
+    virtual void SendComplete(const std::string& data,
+                              std::chrono::milliseconds timeout,
+                              CThreadInterrupt& interrupt) const;
+
+    /**
+     * Read from socket until a terminator character is encountered. Will never consume bytes past
+     * the terminator from the socket.
+     * @param[in] terminator Character up to which to read from the socket.
+     * @param[in] timeout Timeout for the entire operation.
+     * @param[in] interrupt If this is signaled then the operation is canceled.
+     * @param[in] max_data The maximum amount of data (in bytes) to receive. If this many bytes
+     * are received and there is still no terminator, then this method will throw an exception.
+     * @return The data that has been read, without the terminating character.
+     * @throws std::runtime_error if the operation cannot be completed. In this case some bytes may
+     * have been consumed from the socket.
+     */
+    [[nodiscard]] virtual std::string RecvUntilTerminator(uint8_t terminator,
+                                                          std::chrono::milliseconds timeout,
+                                                          CThreadInterrupt& interrupt,
+                                                          size_t max_data) const;
+
+    /**
+     * Check if still connected.
+     * @param[out] errmsg The error string, if the socket has been disconnected.
+     * @return true if connected
+     */
+    [[nodiscard]] virtual bool IsConnected(std::string& errmsg) const;
+
+protected:
+    /**
+     * Contained socket. `INVALID_SOCKET` designates the object is empty.
+     */
+    SOCKET m_socket;
+};
+
+/** Return readable error string for a network error code */
+std::string NetworkErrorString(int err);
+
+/** Close socket and set hSocket to INVALID_SOCKET */
+bool CloseSocket(SOCKET& hSocket);
+
+#endif // DIGIBYTE_UTIL_SOCK_H

src/util/spanparsing.cpp

@@ -0,0 +1,67 @@
+// Copyright (c) 2018-2019 The DigiByte Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include <util/spanparsing.h>
+
+#include <span.h>
+
+#include <string>
+#include <vector>
+
+namespace spanparsing {
+
+bool Const(const std::string& str, Span<const char>& sp)
+{
+    if ((size_t)sp.size() >= str.size() && std::equal(str.begin(), str.end(), sp.begin())) {
+        sp = sp.subspan(str.size());
+        return true;
+    }
+    return false;
+}
+
+bool Func(const std::string& str, Span<const char>& sp)
+{
+    if ((size_t)sp.size() >= str.size() + 2 && sp[str.size()] == '(' && sp[sp.size() - 1] == ')' && std::equal(str.begin(), str.end(), sp.begin())) {
+        sp = sp.subspan(str.size() + 1, sp.size() - str.size() - 2);
+        return true;
+    }
+    return false;
+}
+
+Span<const char> Expr(Span<const char>& sp)
+{
+    int level = 0;
+    auto it = sp.begin();
+    while (it != sp.end()) {
+        if (*it == '(' || *it == '{') {
+            ++level;
+        } else if (level && (*it == ')' || *it == '}')) {
+            --level;
+        } else if (level == 0 && (*it == ')' || *it == '}' || *it == ',')) {
+            break;
+        }
+        ++it;
+    }
+    Span<const char> ret = sp.first(it - sp.begin());
+    sp = sp.subspan(it - sp.begin());
+    return ret;
+}
+
+std::vector<Span<const char>> Split(const Span<const char>& sp, char sep)
+{
+    std::vector<Span<const char>> ret;
+    auto it = sp.begin();
+    auto start = it;
+    while (it != sp.end()) {
+        if (*it == sep) {
+            ret.emplace_back(start, it);
+            start = it + 1;
+        }
+        ++it;
+    }
+    ret.emplace_back(start, it);
+    return ret;
+}
+
+} // namespace spanparsing

src/util/spanparsing.h

@@ -0,0 +1,50 @@
+// Copyright (c) 2018-2019 The DigiByte Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef DIGIBYTE_UTIL_SPANPARSING_H
+#define DIGIBYTE_UTIL_SPANPARSING_H
+
+#include <span.h>
+
+#include <string>
+#include <vector>
+
+namespace spanparsing {
+
+/** Parse a constant.
+ *
+ * If sp's initial part matches str, sp is updated to skip that part, and true is returned.
+ * Otherwise sp is unmodified and false is returned.
+ */
+bool Const(const std::string& str, Span<const char>& sp);
+
+/** Parse a function call.
+ *
+ * If sp's initial part matches str + "(", and sp ends with ")", sp is updated to be the
+ * section between the braces, and true is returned. Otherwise sp is unmodified and false
+ * is returned.
+ */
+bool Func(const std::string& str, Span<const char>& sp);
+
+/** Extract the expression that sp begins with.
+ *
+ * This function will return the initial part of sp, up to (but not including) the first
+ * comma or closing brace, skipping ones that are surrounded by braces. So for example,
+ * for "foo(bar(1),2),3" the initial part "foo(bar(1),2)" will be returned. sp will be
+ * updated to skip the initial part that is returned.
+ */
+Span<const char> Expr(Span<const char>& sp);
+
+/** Split a string on every instance of sep, returning a vector.
+ *
+ * If sep does not occur in sp, a singleton with the entirety of sp is returned.
+ *
+ * Note that this function does not care about braces, so splitting
+ * "foo(bar(1),2),3) on ',' will return {"foo(bar(1)", "2)", "3)"}.
+ */
+std::vector<Span<const char>> Split(const Span<const char>& sp, char sep);
+
+} // namespace spanparsing
+
+#endif // DIGIBYTE_UTIL_SPANPARSING_H

src/util/strencodings.cpp

@@ -0,0 +1,607 @@
+// Copyright (c) 2009-2010 Satoshi Nakamoto
+// Copyright (c) 2009-2019 The Bitcoin Core developers
+// Copyright (c) 2014-2019 The DigiByte Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include <util/strencodings.h>
+#include <util/string.h>
+
+#include <tinyformat.h>
+
+#include <algorithm>
+#include <cstdlib>
+#include <cstring>
+#include <errno.h>
+#include <limits>
+
+static const std::string CHARS_ALPHA_NUM = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
+
+static const std::string SAFE_CHARS[] =
+{
+    CHARS_ALPHA_NUM + " .,;-_/:?@()", // SAFE_CHARS_DEFAULT
+    CHARS_ALPHA_NUM + " .,;-_?@", // SAFE_CHARS_UA_COMMENT
+    CHARS_ALPHA_NUM + ".-_", // SAFE_CHARS_FILENAME
+    CHARS_ALPHA_NUM + "!*'();:@&=+$,/?#[]-_.~%", // SAFE_CHARS_URI
+};
+
+std::string SanitizeString(const std::string& str, int rule)
+{
+    std::string strResult;
+    for (std::string::size_type i = 0; i < str.size(); i++)
+    {
+        if (SAFE_CHARS[rule].find(str[i]) != std::string::npos)
+            strResult.push_back(str[i]);
+    }
+    return strResult;
+}
+
+const signed char p_util_hexdigit[256] =
+{ -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
+  -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
+  -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
+  0,1,2,3,4,5,6,7,8,9,-1,-1,-1,-1,-1,-1,
+  -1,0xa,0xb,0xc,0xd,0xe,0xf,-1,-1,-1,-1,-1,-1,-1,-1,-1,
+  -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
+  -1,0xa,0xb,0xc,0xd,0xe,0xf,-1,-1,-1,-1,-1,-1,-1,-1,-1,
+  -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
+  -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
+  -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
+  -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
+  -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
+  -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
+  -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
+  -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
+  -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1, };
+
+signed char HexDigit(char c)
+{
+    return p_util_hexdigit[(unsigned char)c];
+}
+
+bool IsHex(const std::string& str)
+{
+    for(std::string::const_iterator it(str.begin()); it != str.end(); ++it)
+    {
+        if (HexDigit(*it) < 0)
+            return false;
+    }
+    return (str.size() > 0) && (str.size()%2 == 0);
+}
+
+bool IsHexNumber(const std::string& str)
+{
+    size_t starting_location = 0;
+    if (str.size() > 2 && *str.begin() == '0' && *(str.begin()+1) == 'x') {
+        starting_location = 2;
+    }
+    for (const char c : str.substr(starting_location)) {
+        if (HexDigit(c) < 0) return false;
+    }
+    // Return false for empty string or "0x".
+    return (str.size() > starting_location);
+}
+
+std::vector<unsigned char> ParseHex(const char* psz)
+{
+    // convert hex dump to vector
+    std::vector<unsigned char> vch;
+    while (true)
+    {
+        while (IsSpace(*psz))
+            psz++;
+        signed char c = HexDigit(*psz++);
+        if (c == (signed char)-1)
+            break;
+        unsigned char n = (c << 4);
+        c = HexDigit(*psz++);
+        if (c == (signed char)-1)
+            break;
+        n |= c;
+        vch.push_back(n);
+    }
+    return vch;
+}
+
+std::vector<unsigned char> ParseHex(const std::string& str)
+{
+    return ParseHex(str.c_str());
+}
+
+void SplitHostPort(std::string in, uint16_t& portOut, std::string& hostOut)
+{
+    size_t colon = in.find_last_of(':');
+    // if a : is found, and it either follows a [...], or no other : is in the string, treat it as port separator
+    bool fHaveColon = colon != in.npos;
+    bool fBracketed = fHaveColon && (in[0] == '[' && in[colon - 1] == ']'); // if there is a colon, and in[0]=='[', colon is not 0, so in[colon-1] is safe
+    bool fMultiColon = fHaveColon && (in.find_last_of(':', colon - 1) != in.npos);
+    if (fHaveColon && (colon == 0 || fBracketed || !fMultiColon)) {
+        uint16_t n;
+        if (ParseUInt16(in.substr(colon + 1), &n)) {
+            in = in.substr(0, colon);
+            portOut = n;
+        }
+    }
+    if (in.size() > 0 && in[0] == '[' && in[in.size() - 1] == ']') {
+        hostOut = in.substr(1, in.size() - 2);
+    } else {
+        hostOut = in;
+    }
+}
+
+std::string EncodeBase64(Span<const unsigned char> input)
+{
+    static const char *pbase64 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
+
+    std::string str;
+    str.reserve(((input.size() + 2) / 3) * 4);
+    ConvertBits<8, 6, true>([&](int v) { str += pbase64[v]; }, input.begin(), input.end());
+    while (str.size() % 4) str += '=';
+    return str;
+}
+
+std::string EncodeBase64(const std::string& str)
+{
+    return EncodeBase64(MakeUCharSpan(str));
+}
+
+std::vector<unsigned char> DecodeBase64(const char* p, bool* pf_invalid)
+{
+    static const int decode64_table[256] =
+    {
+        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+        -1, -1, -1, 62, -1, -1, -1, 63, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1,
+        -1, -1, -1, -1, -1,  0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14,
+        15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1, -1, 26, 27, 28,
+        29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48,
+        49, 50, 51, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1
+    };
+
+    const char* e = p;
+    std::vector<uint8_t> val;
+    val.reserve(strlen(p));
+    while (*p != 0) {
+        int x = decode64_table[(unsigned char)*p];
+        if (x == -1) break;
+        val.push_back(x);
+        ++p;
+    }
+
+    std::vector<unsigned char> ret;
+    ret.reserve((val.size() * 3) / 4);
+    bool valid = ConvertBits<6, 8, false>([&](unsigned char c) { ret.push_back(c); }, val.begin(), val.end());
+
+    const char* q = p;
+    while (valid && *p != 0) {
+        if (*p != '=') {
+            valid = false;
+            break;
+        }
+        ++p;
+    }
+    valid = valid && (p - e) % 4 == 0 && p - q < 4;
+    if (pf_invalid) *pf_invalid = !valid;
+
+    return ret;
+}
+
+std::string DecodeBase64(const std::string& str, bool* pf_invalid)
+{
+    if (!ValidAsCString(str)) {
+        if (pf_invalid) {
+            *pf_invalid = true;
+        }
+        return {};
+    }
+    std::vector<unsigned char> vchRet = DecodeBase64(str.c_str(), pf_invalid);
+    return std::string((const char*)vchRet.data(), vchRet.size());
+}
+
+std::string EncodeBase32(Span<const unsigned char> input, bool pad)
+{
+    static const char *pbase32 = "abcdefghijklmnopqrstuvwxyz234567";
+
+    std::string str;
+    str.reserve(((input.size() + 4) / 5) * 8);
+    ConvertBits<8, 5, true>([&](int v) { str += pbase32[v]; }, input.begin(), input.end());
+    if (pad) {
+        while (str.size() % 8) {
+            str += '=';
+        }
+    }
+    return str;
+}
+
+std::string EncodeBase32(const std::string& str, bool pad)
+{
+    return EncodeBase32(MakeUCharSpan(str), pad);
+}
+
+std::vector<unsigned char> DecodeBase32(const char* p, bool* pf_invalid)
+{
+    static const int decode32_table[256] =
+    {
+        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 26, 27, 28, 29, 30, 31, -1, -1, -1, -1,
+        -1, -1, -1, -1, -1,  0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14,
+        15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1, -1,  0,  1,  2,
+         3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22,
+        23, 24, 25, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1
+    };
+
+    const char* e = p;
+    std::vector<uint8_t> val;
+    val.reserve(strlen(p));
+    while (*p != 0) {
+        int x = decode32_table[(unsigned char)*p];
+        if (x == -1) break;
+        val.push_back(x);
+        ++p;
+    }
+
+    std::vector<unsigned char> ret;
+    ret.reserve((val.size() * 5) / 8);
+    bool valid = ConvertBits<5, 8, false>([&](unsigned char c) { ret.push_back(c); }, val.begin(), val.end());
+
+    const char* q = p;
+    while (valid && *p != 0) {
+        if (*p != '=') {
+            valid = false;
+            break;
+        }
+        ++p;
+    }
+    valid = valid && (p - e) % 8 == 0 && p - q < 8;
+    if (pf_invalid) *pf_invalid = !valid;
+
+    return ret;
+}
+
+std::string DecodeBase32(const std::string& str, bool* pf_invalid)
+{
+    if (!ValidAsCString(str)) {
+        if (pf_invalid) {
+            *pf_invalid = true;
+        }
+        return {};
+    }
+    std::vector<unsigned char> vchRet = DecodeBase32(str.c_str(), pf_invalid);
+    return std::string((const char*)vchRet.data(), vchRet.size());
+}
+
+[[nodiscard]] static bool ParsePrechecks(const std::string& str)
+{
+    if (str.empty()) // No empty string allowed
+        return false;
+    if (str.size() >= 1 && (IsSpace(str[0]) || IsSpace(str[str.size()-1]))) // No padding allowed
+        return false;
+    if (!ValidAsCString(str)) // No embedded NUL characters allowed
+        return false;
+    return true;
+}
+
+bool ParseInt32(const std::string& str, int32_t *out)
+{
+    if (!ParsePrechecks(str))
+        return false;
+    char *endp = nullptr;
+    errno = 0; // strtol will not set errno if valid
+    long int n = strtol(str.c_str(), &endp, 10);
+    if(out) *out = (int32_t)n;
+    // Note that strtol returns a *long int*, so even if strtol doesn't report an over/underflow
+    // we still have to check that the returned value is within the range of an *int32_t*. On 64-bit
+    // platforms the size of these types may be different.
+    return endp && *endp == 0 && !errno &&
+        n >= std::numeric_limits<int32_t>::min() &&
+        n <= std::numeric_limits<int32_t>::max();
+}
+
+bool ParseInt64(const std::string& str, int64_t *out)
+{
+    if (!ParsePrechecks(str))
+        return false;
+    char *endp = nullptr;
+    errno = 0; // strtoll will not set errno if valid
+    long long int n = strtoll(str.c_str(), &endp, 10);
+    if(out) *out = (int64_t)n;
+    // Note that strtoll returns a *long long int*, so even if strtol doesn't report an over/underflow
+    // we still have to check that the returned value is within the range of an *int64_t*.
+    return endp && *endp == 0 && !errno &&
+        n >= std::numeric_limits<int64_t>::min() &&
+        n <= std::numeric_limits<int64_t>::max();
+}
+
+bool ParseUInt8(const std::string& str, uint8_t *out)
+{
+    uint32_t u32;
+    if (!ParseUInt32(str, &u32) || u32 > std::numeric_limits<uint8_t>::max()) {
+        return false;
+    }
+    if (out != nullptr) {
+        *out = static_cast<uint8_t>(u32);
+    }
+    return true;
+}
+
+bool ParseUInt16(const std::string& str, uint16_t* out)
+{
+    uint32_t u32;
+    if (!ParseUInt32(str, &u32) || u32 > std::numeric_limits<uint16_t>::max()) {
+        return false;
+    }
+    if (out != nullptr) {
+        *out = static_cast<uint16_t>(u32);
+    }
+    return true;
+}
+
+bool ParseUInt32(const std::string& str, uint32_t *out)
+{
+    if (!ParsePrechecks(str))
+        return false;
+    if (str.size() >= 1 && str[0] == '-') // Reject negative values, unfortunately strtoul accepts these by default if they fit in the range
+        return false;
+    char *endp = nullptr;
+    errno = 0; // strtoul will not set errno if valid
+    unsigned long int n = strtoul(str.c_str(), &endp, 10);
+    if(out) *out = (uint32_t)n;
+    // Note that strtoul returns a *unsigned long int*, so even if it doesn't report an over/underflow
+    // we still have to check that the returned value is within the range of an *uint32_t*. On 64-bit
+    // platforms the size of these types may be different.
+    return endp && *endp == 0 && !errno &&
+        n <= std::numeric_limits<uint32_t>::max();
+}
+
+bool ParseUInt64(const std::string& str, uint64_t *out)
+{
+    if (!ParsePrechecks(str))
+        return false;
+    if (str.size() >= 1 && str[0] == '-') // Reject negative values, unfortunately strtoull accepts these by default if they fit in the range
+        return false;
+    char *endp = nullptr;
+    errno = 0; // strtoull will not set errno if valid
+    unsigned long long int n = strtoull(str.c_str(), &endp, 10);
+    if(out) *out = (uint64_t)n;
+    // Note that strtoull returns a *unsigned long long int*, so even if it doesn't report an over/underflow
+    // we still have to check that the returned value is within the range of an *uint64_t*.
+    return endp && *endp == 0 && !errno &&
+        n <= std::numeric_limits<uint64_t>::max();
+}
+
+
+bool ParseDouble(const std::string& str, double *out)
+{
+    if (!ParsePrechecks(str))
+        return false;
+    if (str.size() >= 2 && str[0] == '0' && str[1] == 'x') // No hexadecimal floats allowed
+        return false;
+    std::istringstream text(str);
+    text.imbue(std::locale::classic());
+    double result;
+    text >> result;
+    if(out) *out = result;
+    return text.eof() && !text.fail();
+}
+
+std::string FormatParagraph(const std::string& in, size_t width, size_t indent)
+{
+    std::stringstream out;
+    size_t ptr = 0;
+    size_t indented = 0;
+    while (ptr < in.size())
+    {
+        size_t lineend = in.find_first_of('\n', ptr);
+        if (lineend == std::string::npos) {
+            lineend = in.size();
+        }
+        const size_t linelen = lineend - ptr;
+        const size_t rem_width = width - indented;
+        if (linelen <= rem_width) {
+            out << in.substr(ptr, linelen + 1);
+            ptr = lineend + 1;
+            indented = 0;
+        } else {
+            size_t finalspace = in.find_last_of(" \n", ptr + rem_width);
+            if (finalspace == std::string::npos || finalspace < ptr) {
+                // No place to break; just include the entire word and move on
+                finalspace = in.find_first_of("\n ", ptr);
+                if (finalspace == std::string::npos) {
+                    // End of the string, just add it and break
+                    out << in.substr(ptr);
+                    break;
+                }
+            }
+            out << in.substr(ptr, finalspace - ptr) << "\n";
+            if (in[finalspace] == '\n') {
+                indented = 0;
+            } else if (indent) {
+                out << std::string(indent, ' ');
+                indented = indent;
+            }
+            ptr = finalspace + 1;
+        }
+    }
+    return out.str();
+}
+
+int64_t atoi64(const std::string& str)
+{
+#ifdef _MSC_VER
+    return _atoi64(str.c_str());
+#else
+    return strtoll(str.c_str(), nullptr, 10);
+#endif
+}
+
+int atoi(const std::string& str)
+{
+    return atoi(str.c_str());
+}
+
+/** Upper bound for mantissa.
+ * 10^18-1 is the largest arbitrary decimal that will fit in a signed 64-bit integer.
+ * Larger integers cannot consist of arbitrary combinations of 0-9:
+ *
+ *   999999999999999999  1^18-1
+ *  9223372036854775807  (1<<63)-1  (max int64_t)
+ *  9999999999999999999  1^19-1     (would overflow)
+ */
+static const int64_t UPPER_BOUND = 1000000000000000000LL - 1LL;
+
+/** Helper function for ParseFixedPoint */
+static inline bool ProcessMantissaDigit(char ch, int64_t &mantissa, int &mantissa_tzeros)
+{
+    if(ch == '0')
+        ++mantissa_tzeros;
+    else {
+        for (int i=0; i<=mantissa_tzeros; ++i) {
+            if (mantissa > (UPPER_BOUND / 10LL))
+                return false; /* overflow */
+            mantissa *= 10;
+        }
+        mantissa += ch - '0';
+        mantissa_tzeros = 0;
+    }
+    return true;
+}
+
+bool ParseFixedPoint(const std::string &val, int decimals, int64_t *amount_out)
+{
+    int64_t mantissa = 0;
+    int64_t exponent = 0;
+    int mantissa_tzeros = 0;
+    bool mantissa_sign = false;
+    bool exponent_sign = false;
+    int ptr = 0;
+    int end = val.size();
+    int point_ofs = 0;
+
+    if (ptr < end && val[ptr] == '-') {
+        mantissa_sign = true;
+        ++ptr;
+    }
+    if (ptr < end)
+    {
+        if (val[ptr] == '0') {
+            /* pass single 0 */
+            ++ptr;
+        } else if (val[ptr] >= '1' && val[ptr] <= '9') {
+            while (ptr < end && IsDigit(val[ptr])) {
+                if (!ProcessMantissaDigit(val[ptr], mantissa, mantissa_tzeros))
+                    return false; /* overflow */
+                ++ptr;
+            }
+        } else return false; /* missing expected digit */
+    } else return false; /* empty string or loose '-' */
+    if (ptr < end && val[ptr] == '.')
+    {
+        ++ptr;
+        if (ptr < end && IsDigit(val[ptr]))
+        {
+            while (ptr < end && IsDigit(val[ptr])) {
+                if (!ProcessMantissaDigit(val[ptr], mantissa, mantissa_tzeros))
+                    return false; /* overflow */
+                ++ptr;
+                ++point_ofs;
+            }
+        } else return false; /* missing expected digit */
+    }
+    if (ptr < end && (val[ptr] == 'e' || val[ptr] == 'E'))
+    {
+        ++ptr;
+        if (ptr < end && val[ptr] == '+')
+            ++ptr;
+        else if (ptr < end && val[ptr] == '-') {
+            exponent_sign = true;
+            ++ptr;
+        }
+        if (ptr < end && IsDigit(val[ptr])) {
+            while (ptr < end && IsDigit(val[ptr])) {
+                if (exponent > (UPPER_BOUND / 10LL))
+                    return false; /* overflow */
+                exponent = exponent * 10 + val[ptr] - '0';
+                ++ptr;
+            }
+        } else return false; /* missing expected digit */
+    }
+    if (ptr != end)
+        return false; /* trailing garbage */
+
+    /* finalize exponent */
+    if (exponent_sign)
+        exponent = -exponent;
+    exponent = exponent - point_ofs + mantissa_tzeros;
+
+    /* finalize mantissa */
+    if (mantissa_sign)
+        mantissa = -mantissa;
+
+    /* convert to one 64-bit fixed-point value */
+    exponent += decimals;
+    if (exponent < 0)
+        return false; /* cannot represent values smaller than 10^-decimals */
+    if (exponent >= 18)
+        return false; /* cannot represent values larger than or equal to 10^(18-decimals) */
+
+    for (int i=0; i < exponent; ++i) {
+        if (mantissa > (UPPER_BOUND / 10LL) || mantissa < -(UPPER_BOUND / 10LL))
+            return false; /* overflow */
+        mantissa *= 10;
+    }
+    if (mantissa > UPPER_BOUND || mantissa < -UPPER_BOUND)
+        return false; /* overflow */
+
+    if (amount_out)
+        *amount_out = mantissa;
+
+    return true;
+}
+
+std::string ToLower(const std::string& str)
+{
+    std::string r;
+    for (auto ch : str) r += ToLower((unsigned char)ch);
+    return r;
+}
+
+std::string ToUpper(const std::string& str)
+{
+    std::string r;
+    for (auto ch : str) r += ToUpper((unsigned char)ch);
+    return r;
+}
+
+std::string Capitalize(std::string str)
+{
+    if (str.empty()) return str;
+    str[0] = ToUpper(str.front());
+    return str;
+}
+
+std::string HexStr(const Span<const uint8_t> s)
+{
+    std::string rv(s.size() * 2, '\0');
+    static constexpr char hexmap[16] = { '0', '1', '2', '3', '4', '5', '6', '7',
+                                         '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' };
+    auto it = rv.begin();
+    for (uint8_t v : s) {
+        *it++ = hexmap[v >> 4];
+        *it++ = hexmap[v & 15];
+    }
+    assert(it == rv.end());
+    return rv;
+}

src/util/strencodings.h

@@ -0,0 +1,273 @@
+// Copyright (c) 2009-2010 Satoshi Nakamoto
+// Copyright (c) 2009-2020 The DigiByte Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+/**
+ * Utilities for converting data from/to strings.
+ */
+#ifndef DIGIBYTE_UTIL_STRENCODINGS_H
+#define DIGIBYTE_UTIL_STRENCODINGS_H
+
+#include <attributes.h>
+#include <span.h>
+
+#include <cstdint>
+#include <iterator>
+#include <string>
+#include <vector>
+
+#define BEGIN(a)            ((char*)&(a))
+#define END(a)              ((char*)&((&(a))[1]))
+#define UBEGIN(a)           ((unsigned char*)&(a))
+#define UEND(a)             ((unsigned char*)&((&(a))[1]))
+#define ARRAYLEN(array)     (sizeof(array)/sizeof((array)[0]))
+
+/** Used by SanitizeString() */
+enum SafeChars
+{
+    SAFE_CHARS_DEFAULT, //!< The full set of allowed chars
+    SAFE_CHARS_UA_COMMENT, //!< BIP-0014 subset
+    SAFE_CHARS_FILENAME, //!< Chars allowed in filenames
+    SAFE_CHARS_URI, //!< Chars allowed in URIs (RFC 3986)
+};
+
+/**
+* Remove unsafe chars. Safe chars chosen to allow simple messages/URLs/email
+* addresses, but avoid anything even possibly remotely dangerous like & or >
+* @param[in] str    The string to sanitize
+* @param[in] rule   The set of safe chars to choose (default: least restrictive)
+* @return           A new string without unsafe chars
+*/
+std::string SanitizeString(const std::string& str, int rule = SAFE_CHARS_DEFAULT);
+std::vector<unsigned char> ParseHex(const char* psz);
+std::vector<unsigned char> ParseHex(const std::string& str);
+signed char HexDigit(char c);
+/* Returns true if each character in str is a hex character, and has an even
+ * number of hex digits.*/
+bool IsHex(const std::string& str);
+/**
+* Return true if the string is a hex number, optionally prefixed with "0x"
+*/
+bool IsHexNumber(const std::string& str);
+std::vector<unsigned char> DecodeBase64(const char* p, bool* pf_invalid = nullptr);
+std::string DecodeBase64(const std::string& str, bool* pf_invalid = nullptr);
+std::string EncodeBase64(Span<const unsigned char> input);
+std::string EncodeBase64(const std::string& str);
+std::vector<unsigned char> DecodeBase32(const char* p, bool* pf_invalid = nullptr);
+std::string DecodeBase32(const std::string& str, bool* pf_invalid = nullptr);
+
+/**
+ * Base32 encode.
+ * If `pad` is true, then the output will be padded with '=' so that its length
+ * is a multiple of 8.
+ */
+std::string EncodeBase32(Span<const unsigned char> input, bool pad = true);
+
+/**
+ * Base32 encode.
+ * If `pad` is true, then the output will be padded with '=' so that its length
+ * is a multiple of 8.
+ */
+std::string EncodeBase32(const std::string& str, bool pad = true);
+
+void SplitHostPort(std::string in, uint16_t& portOut, std::string& hostOut);
+int64_t atoi64(const std::string& str);
+int atoi(const std::string& str);
+
+/**
+ * Tests if the given character is a decimal digit.
+ * @param[in] c     character to test
+ * @return          true if the argument is a decimal digit; otherwise false.
+ */
+constexpr bool IsDigit(char c)
+{
+    return c >= '0' && c <= '9';
+}
+
+/**
+ * Tests if the given character is a whitespace character. The whitespace characters
+ * are: space, form-feed ('\f'), newline ('\n'), carriage return ('\r'), horizontal
+ * tab ('\t'), and vertical tab ('\v').
+ *
+ * This function is locale independent. Under the C locale this function gives the
+ * same result as std::isspace.
+ *
+ * @param[in] c     character to test
+ * @return          true if the argument is a whitespace character; otherwise false
+ */
+constexpr inline bool IsSpace(char c) noexcept {
+    return c == ' ' || c == '\f' || c == '\n' || c == '\r' || c == '\t' || c == '\v';
+}
+
+/**
+ * Convert string to signed 32-bit integer with strict parse error feedback.
+ * @returns true if the entire string could be parsed as valid integer,
+ *   false if not the entire string could be parsed or when overflow or underflow occurred.
+ */
+[[nodiscard]] bool ParseInt32(const std::string& str, int32_t *out);
+
+/**
+ * Convert string to signed 64-bit integer with strict parse error feedback.
+ * @returns true if the entire string could be parsed as valid integer,
+ *   false if not the entire string could be parsed or when overflow or underflow occurred.
+ */
+[[nodiscard]] bool ParseInt64(const std::string& str, int64_t *out);
+
+/**
+ * Convert decimal string to unsigned 8-bit integer with strict parse error feedback.
+ * @returns true if the entire string could be parsed as valid integer,
+ *   false if not the entire string could be parsed or when overflow or underflow occurred.
+ */
+[[nodiscard]] bool ParseUInt8(const std::string& str, uint8_t *out);
+
+/**
+ * Convert decimal string to unsigned 16-bit integer with strict parse error feedback.
+ * @returns true if the entire string could be parsed as valid integer,
+ *   false if the entire string could not be parsed or if overflow or underflow occurred.
+ */
+[[nodiscard]] bool ParseUInt16(const std::string& str, uint16_t* out);
+
+/**
+ * Convert decimal string to unsigned 32-bit integer with strict parse error feedback.
+ * @returns true if the entire string could be parsed as valid integer,
+ *   false if not the entire string could be parsed or when overflow or underflow occurred.
+ */
+[[nodiscard]] bool ParseUInt32(const std::string& str, uint32_t *out);
+
+/**
+ * Convert decimal string to unsigned 64-bit integer with strict parse error feedback.
+ * @returns true if the entire string could be parsed as valid integer,
+ *   false if not the entire string could be parsed or when overflow or underflow occurred.
+ */
+[[nodiscard]] bool ParseUInt64(const std::string& str, uint64_t *out);
+
+/**
+ * Convert string to double with strict parse error feedback.
+ * @returns true if the entire string could be parsed as valid double,
+ *   false if not the entire string could be parsed or when overflow or underflow occurred.
+ */
+[[nodiscard]] bool ParseDouble(const std::string& str, double *out);
+
+/**
+ * Convert a span of bytes to a lower-case hexadecimal string.
+ */
+std::string HexStr(const Span<const uint8_t> s);
+inline std::string HexStr(const Span<const char> s) { return HexStr(MakeUCharSpan(s)); }
+
+/**
+ * Format a paragraph of text to a fixed width, adding spaces for
+ * indentation to any added line.
+ */
+std::string FormatParagraph(const std::string& in, size_t width = 79, size_t indent = 0);
+
+/**
+ * Timing-attack-resistant comparison.
+ * Takes time proportional to length
+ * of first argument.
+ */
+template <typename T>
+bool TimingResistantEqual(const T& a, const T& b)
+{
+    if (b.size() == 0) return a.size() == 0;
+    size_t accumulator = a.size() ^ b.size();
+    for (size_t i = 0; i < a.size(); i++)
+        accumulator |= a[i] ^ b[i%b.size()];
+    return accumulator == 0;
+}
+
+/** Parse number as fixed point according to JSON number syntax.
+ * See https://json.org/number.gif
+ * @returns true on success, false on error.
+ * @note The result must be in the range (-10^18,10^18), otherwise an overflow error will trigger.
+ */
+[[nodiscard]] bool ParseFixedPoint(const std::string &val, int decimals, int64_t *amount_out);
+
+/** Convert from one power-of-2 number base to another. */
+template<int frombits, int tobits, bool pad, typename O, typename I>
+bool ConvertBits(const O& outfn, I it, I end) {
+    size_t acc = 0;
+    size_t bits = 0;
+    constexpr size_t maxv = (1 << tobits) - 1;
+    constexpr size_t max_acc = (1 << (frombits + tobits - 1)) - 1;
+    while (it != end) {
+        acc = ((acc << frombits) | *it) & max_acc;
+        bits += frombits;
+        while (bits >= tobits) {
+            bits -= tobits;
+            outfn((acc >> bits) & maxv);
+        }
+        ++it;
+    }
+    if (pad) {
+        if (bits) outfn((acc << (tobits - bits)) & maxv);
+    } else if (bits >= frombits || ((acc << (tobits - bits)) & maxv)) {
+        return false;
+    }
+    return true;
+}
+
+/**
+ * Converts the given character to its lowercase equivalent.
+ * This function is locale independent. It only converts uppercase
+ * characters in the standard 7-bit ASCII range.
+ * This is a feature, not a limitation.
+ *
+ * @param[in] c     the character to convert to lowercase.
+ * @return          the lowercase equivalent of c; or the argument
+ *                  if no conversion is possible.
+ */
+constexpr char ToLower(char c)
+{
+    return (c >= 'A' && c <= 'Z' ? (c - 'A') + 'a' : c);
+}
+
+/**
+ * Returns the lowercase equivalent of the given string.
+ * This function is locale independent. It only converts uppercase
+ * characters in the standard 7-bit ASCII range.
+ * This is a feature, not a limitation.
+ *
+ * @param[in] str   the string to convert to lowercase.
+ * @returns         lowercased equivalent of str
+ */
+std::string ToLower(const std::string& str);
+
+/**
+ * Converts the given character to its uppercase equivalent.
+ * This function is locale independent. It only converts lowercase
+ * characters in the standard 7-bit ASCII range.
+ * This is a feature, not a limitation.
+ *
+ * @param[in] c     the character to convert to uppercase.
+ * @return          the uppercase equivalent of c; or the argument
+ *                  if no conversion is possible.
+ */
+constexpr char ToUpper(char c)
+{
+    return (c >= 'a' && c <= 'z' ? (c - 'a') + 'A' : c);
+}
+
+/**
+ * Returns the uppercase equivalent of the given string.
+ * This function is locale independent. It only converts lowercase
+ * characters in the standard 7-bit ASCII range.
+ * This is a feature, not a limitation.
+ *
+ * @param[in] str   the string to convert to uppercase.
+ * @returns         UPPERCASED EQUIVALENT OF str
+ */
+std::string ToUpper(const std::string& str);
+
+/**
+ * Capitalizes the first character of the given string.
+ * This function is locale independent. It only converts lowercase
+ * characters in the standard 7-bit ASCII range.
+ * This is a feature, not a limitation.
+ *
+ * @param[in] str   the string to capitalize.
+ * @returns         string with the first letter capitalized.
+ */
+std::string Capitalize(std::string str);
+
+#endif // DIGIBYTE_UTIL_STRENCODINGS_H

src/util/string.cpp

@@ -0,0 +1,5 @@
+// Copyright (c) 2019 The DigiByte Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include <util/string.h>

src/util/string.h

@@ -0,0 +1,99 @@
+// Copyright (c) 2019-2020 The DigiByte Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef DIGIBYTE_UTIL_STRING_H
+#define DIGIBYTE_UTIL_STRING_H
+
+#include <attributes.h>
+
+#include <algorithm>
+#include <array>
+#include <cstring>
+#include <locale>
+#include <sstream>
+#include <string>
+#include <vector>
+#include <cstdint>
+
+[[nodiscard]] inline std::string TrimString(const std::string& str, const std::string& pattern = " \f\n\r\t\v")
+{
+    std::string::size_type front = str.find_first_not_of(pattern);
+    if (front == std::string::npos) {
+        return std::string();
+    }
+    std::string::size_type end = str.find_last_not_of(pattern);
+    return str.substr(front, end - front + 1);
+}
+
+[[nodiscard]] inline std::string RemovePrefix(const std::string& str, const std::string& prefix)
+{
+    if (str.substr(0, prefix.size()) == prefix) {
+        return str.substr(prefix.size());
+    }
+    return str;
+}
+
+/**
+ * Join a list of items
+ *
+ * @param list       The list to join
+ * @param separator  The separator
+ * @param unary_op   Apply this operator to each item in the list
+ */
+template <typename T, typename BaseType, typename UnaryOp>
+auto Join(const std::vector<T>& list, const BaseType& separator, UnaryOp unary_op)
+    -> decltype(unary_op(list.at(0)))
+{
+    decltype(unary_op(list.at(0))) ret;
+    for (size_t i = 0; i < list.size(); ++i) {
+        if (i > 0) ret += separator;
+        ret += unary_op(list.at(i));
+    }
+    return ret;
+}
+
+template <typename T>
+T Join(const std::vector<T>& list, const T& separator)
+{
+    return Join(list, separator, [](const T& i) { return i; });
+}
+
+// Explicit overload needed for c_str arguments, which would otherwise cause a substitution failure in the template above.
+inline std::string Join(const std::vector<std::string>& list, const std::string& separator)
+{
+    return Join<std::string>(list, separator);
+}
+
+/**
+ * Check if a string does not contain any embedded NUL (\0) characters
+ */
+[[nodiscard]] inline bool ValidAsCString(const std::string& str) noexcept
+{
+    return str.size() == strlen(str.c_str());
+}
+
+/**
+ * Locale-independent version of std::to_string
+ */
+template <typename T>
+std::string ToString(const T& t)
+{
+    std::ostringstream oss;
+    oss.imbue(std::locale::classic());
+    oss << t;
+    return oss.str();
+}
+
+/**
+ * Check whether a container begins with the given prefix.
+ */
+template <typename T1, size_t PREFIX_LEN>
+[[nodiscard]] inline bool HasPrefix(const T1& obj,
+                                const std::array<uint8_t, PREFIX_LEN>& prefix)
+{
+    return obj.size() >= PREFIX_LEN &&
+           std::equal(std::begin(prefix), std::end(prefix), std::begin(obj));
+}
+
+#endif // DIGIBYTE_UTIL_STRENCODINGS_H

src/util/system.h

@@ -0,0 +1,544 @@
+// Copyright (c) 2009-2010 Satoshi Nakamoto
+// Copyright (c) 2009-2020 The DigiByte Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+/**
+ * Server/client environment: argument handling, config file parsing,
+ * thread wrappers, startup time
+ */
+#ifndef DIGIBYTE_UTIL_SYSTEM_H
+#define DIGIBYTE_UTIL_SYSTEM_H
+
+#if defined(HAVE_CONFIG_H)
+#include <config/vexta-config.h>
+#endif
+
+#include <attributes.h>
+#include <compat.h>
+#include <compat/assumptions.h>
+#include <fs.h>
+#include <logging.h>
+#include <sync.h>
+#include <tinyformat.h>
+#include <util/settings.h>
+#include <util/time.h>
+
+#include <any>
+#include <exception>
+#include <map>
+#include <optional>
+#include <set>
+#include <stdint.h>
+#include <string>
+#include <utility>
+#include <vector>
+
+class UniValue;
+
+// Application startup time (used for uptime calculation)
+int64_t GetStartupTime();
+
+extern const char * const DIGIBYTE_CONF_FILENAME;
+extern const char * const DIGIBYTE_SETTINGS_FILENAME;
+
+
+void SetupEnvironment();
+bool SetupNetworking();
+
+template<typename... Args>
+bool error(const char* fmt, const Args&... args)
+{
+    LogPrintf("ERROR: %s\n", tfm::format(fmt, args...));
+    return false;
+}
+
+void PrintExceptionContinue(const std::exception *pex, const char* pszThread);
+
+/**
+ * Ensure file contents are fully committed to disk, using a platform-specific
+ * feature analogous to fsync().
+ */
+bool FileCommit(FILE *file);
+
+/**
+ * Sync directory contents. This is required on some environments to ensure that
+ * newly created files are committed to disk.
+ */
+void DirectoryCommit(const fs::path &dirname);
+
+bool TruncateFile(FILE *file, unsigned int length);
+int RaiseFileDescriptorLimit(int nMinFD);
+void AllocateFileRange(FILE *file, unsigned int offset, unsigned int length);
+[[nodiscard]] bool RenameOver(fs::path src, fs::path dest);
+bool LockDirectory(const fs::path& directory, const std::string lockfile_name, bool probe_only=false);
+void UnlockDirectory(const fs::path& directory, const std::string& lockfile_name);
+bool DirIsWritable(const fs::path& directory);
+bool CheckDiskSpace(const fs::path& dir, uint64_t additional_bytes = 0);
+
+/** Get the size of a file by scanning it.
+ *
+ * @param[in] path The file path
+ * @param[in] max Stop seeking beyond this limit
+ * @return The file size or max
+ */
+std::streampos GetFileSize(const char* path, std::streamsize max = std::numeric_limits<std::streamsize>::max());
+
+/** Release all directory locks. This is used for unit testing only, at runtime
+ * the global destructor will take care of the locks.
+ */
+void ReleaseDirectoryLocks();
+
+bool TryCreateDirectories(const fs::path& p);
+fs::path GetDefaultDataDir();
+// Return true if -datadir option points to a valid directory or is not specified.
+bool CheckDataDirOption();
+fs::path GetConfigFile(const std::string& confPath);
+#ifdef WIN32
+fs::path GetSpecialFolderPath(int nFolder, bool fCreate = true);
+#endif
+#ifndef WIN32
+std::string ShellEscape(const std::string& arg);
+#endif
+#if HAVE_SYSTEM
+void runCommand(const std::string& strCommand);
+#endif
+/**
+ * Execute a command which returns JSON, and parse the result.
+ *
+ * @param str_command The command to execute, including any arguments
+ * @param str_std_in string to pass to stdin
+ * @return parsed JSON
+ */
+UniValue RunCommandParseJSON(const std::string& str_command, const std::string& str_std_in="");
+
+/**
+ * Most paths passed as configuration arguments are treated as relative to
+ * the datadir if they are not absolute.
+ *
+ * @param path The path to be conditionally prefixed with datadir.
+ * @param net_specific Use network specific datadir variant
+ * @return The normalized path.
+ */
+fs::path AbsPathForConfigVal(const fs::path& path, bool net_specific = true);
+
+inline bool IsSwitchChar(char c)
+{
+#ifdef WIN32
+    return c == '-' || c == '/';
+#else
+    return c == '-';
+#endif
+}
+
+enum class OptionsCategory {
+    OPTIONS,
+    CONNECTION,
+    WALLET,
+    WALLET_DEBUG_TEST,
+    ZMQ,
+    DEBUG_TEST,
+    CHAINPARAMS,
+    NODE_RELAY,
+    BLOCK_CREATION,
+    RPC,
+    GUI,
+    COMMANDS,
+    REGISTER_COMMANDS,
+
+    HIDDEN // Always the last option to avoid printing these in the help
+};
+
+struct SectionInfo
+{
+    std::string m_name;
+    std::string m_file;
+    int m_line;
+};
+
+class ArgsManager
+{
+public:
+    enum Flags : uint32_t {
+        // Boolean options can accept negation syntax -noOPTION or -noOPTION=1
+        ALLOW_BOOL = 0x01,
+        ALLOW_INT = 0x02,
+        ALLOW_STRING = 0x04,
+        ALLOW_ANY = ALLOW_BOOL | ALLOW_INT | ALLOW_STRING,
+        DEBUG_ONLY = 0x100,
+        /* Some options would cause cross-contamination if values for
+         * mainnet were used while running on regtest/testnet (or vice-versa).
+         * Setting them as NETWORK_ONLY ensures that sharing a config file
+         * between mainnet and regtest/testnet won't cause problems due to these
+         * parameters by accident. */
+        NETWORK_ONLY = 0x200,
+        // This argument's value is sensitive (such as a password).
+        SENSITIVE = 0x400,
+        COMMAND = 0x800,
+    };
+
+protected:
+    struct Arg
+    {
+        std::string m_help_param;
+        std::string m_help_text;
+        unsigned int m_flags;
+    };
+
+    mutable RecursiveMutex cs_args;
+    util::Settings m_settings GUARDED_BY(cs_args);
+    std::vector<std::string> m_command GUARDED_BY(cs_args);
+    std::string m_network GUARDED_BY(cs_args);
+    std::set<std::string> m_network_only_args GUARDED_BY(cs_args);
+    std::map<OptionsCategory, std::map<std::string, Arg>> m_available_args GUARDED_BY(cs_args);
+    bool m_accept_any_command GUARDED_BY(cs_args){true};
+    std::list<SectionInfo> m_config_sections GUARDED_BY(cs_args);
+    mutable fs::path m_cached_blocks_path GUARDED_BY(cs_args);
+    mutable fs::path m_cached_datadir_path GUARDED_BY(cs_args);
+    mutable fs::path m_cached_network_datadir_path GUARDED_BY(cs_args);
+
+    [[nodiscard]] bool ReadConfigStream(std::istream& stream, const std::string& filepath, std::string& error, bool ignore_invalid_keys = false);
+
+    /**
+     * Returns true if settings values from the default section should be used,
+     * depending on the current network and whether the setting is
+     * network-specific.
+     */
+    bool UseDefaultSection(const std::string& arg) const EXCLUSIVE_LOCKS_REQUIRED(cs_args);
+
+    /**
+     * Get setting value.
+     *
+     * Result will be null if setting was unset, true if "-setting" argument was passed
+     * false if "-nosetting" argument was passed, and a string if a "-setting=value"
+     * argument was passed.
+     */
+    util::SettingsValue GetSetting(const std::string& arg) const;
+
+    /**
+     * Get list of setting values.
+     */
+    std::vector<util::SettingsValue> GetSettingsList(const std::string& arg) const;
+
+public:
+    ArgsManager();
+    ~ArgsManager();
+
+    /**
+     * Select the network in use
+     */
+    void SelectConfigNetwork(const std::string& network);
+
+    [[nodiscard]] bool ParseParameters(int argc, const char* const argv[], std::string& error);
+    [[nodiscard]] bool ReadConfigFiles(std::string& error, bool ignore_invalid_keys = false);
+
+    /**
+     * Log warnings for options in m_section_only_args when
+     * they are specified in the default section but not overridden
+     * on the command line or in a network-specific section in the
+     * config file.
+     */
+    const std::set<std::string> GetUnsuitableSectionOnlyArgs() const;
+
+    /**
+     * Log warnings for unrecognized section names in the config file.
+     */
+    const std::list<SectionInfo> GetUnrecognizedSections() const;
+
+    struct Command {
+        /** The command (if one has been registered with AddCommand), or empty */
+        std::string command;
+        /**
+         * If command is non-empty: Any args that followed it
+         * If command is empty: The unregistered command and any args that followed it
+         */
+        std::vector<std::string> args;
+    };
+    /**
+     * Get the command and command args (returns std::nullopt if no command provided)
+     */
+    std::optional<const Command> GetCommand() const;
+
+    /**
+     * Get blocks directory path
+     *
+     * @return Blocks path which is network specific
+     */
+    const fs::path& GetBlocksDirPath() const;
+
+    /**
+     * Get data directory path
+     *
+     * @return Absolute path on success, otherwise an empty path when a non-directory path would be returned
+     * @post Returned directory path is created unless it is empty
+     */
+    const fs::path& GetDataDirBase() const { return GetDataDir(false); }
+
+    /**
+     * Get data directory path with appended network identifier
+     *
+     * @return Absolute path on success, otherwise an empty path when a non-directory path would be returned
+     * @post Returned directory path is created unless it is empty
+     */
+    const fs::path& GetDataDirNet() const { return GetDataDir(true); }
+
+    /**
+     * Clear cached directory paths
+     */
+    void ClearPathCache();
+
+    /**
+     * Return a vector of strings of the given argument
+     *
+     * @param strArg Argument to get (e.g. "-foo")
+     * @return command-line arguments
+     */
+    std::vector<std::string> GetArgs(const std::string& strArg) const;
+
+    /**
+     * Return true if the given argument has been manually set
+     *
+     * @param strArg Argument to get (e.g. "-foo")
+     * @return true if the argument has been set
+     */
+    bool IsArgSet(const std::string& strArg) const;
+
+    /**
+     * Return true if the argument was originally passed as a negated option,
+     * i.e. -nofoo.
+     *
+     * @param strArg Argument to get (e.g. "-foo")
+     * @return true if the argument was passed negated
+     */
+    bool IsArgNegated(const std::string& strArg) const;
+
+    /**
+     * Return string argument or default value
+     *
+     * @param strArg Argument to get (e.g. "-foo")
+     * @param strDefault (e.g. "1")
+     * @return command-line argument or default value
+     */
+    std::string GetArg(const std::string& strArg, const std::string& strDefault) const;
+
+    /**
+     * Return integer argument or default value
+     *
+     * @param strArg Argument to get (e.g. "-foo")
+     * @param nDefault (e.g. 1)
+     * @return command-line argument (0 if invalid number) or default value
+     */
+    int64_t GetArg(const std::string& strArg, int64_t nDefault) const;
+
+    /**
+     * Return boolean argument or default value
+     *
+     * @param strArg Argument to get (e.g. "-foo")
+     * @param fDefault (true or false)
+     * @return command-line argument or default value
+     */
+    bool GetBoolArg(const std::string& strArg, bool fDefault) const;
+
+    /**
+     * Set an argument if it doesn't already have a value
+     *
+     * @param strArg Argument to set (e.g. "-foo")
+     * @param strValue Value (e.g. "1")
+     * @return true if argument gets set, false if it already had a value
+     */
+    bool SoftSetArg(const std::string& strArg, const std::string& strValue);
+
+    /**
+     * Set a boolean argument if it doesn't already have a value
+     *
+     * @param strArg Argument to set (e.g. "-foo")
+     * @param fValue Value (e.g. false)
+     * @return true if argument gets set, false if it already had a value
+     */
+    bool SoftSetBoolArg(const std::string& strArg, bool fValue);
+
+    // Forces an arg setting. Called by SoftSetArg() if the arg hasn't already
+    // been set. Also called directly in testing.
+    void ForceSetArg(const std::string& strArg, const std::string& strValue);
+
+    /**
+     * Returns the appropriate chain name from the program arguments.
+     * @return CBaseChainParams::MAIN by default; raises runtime error if an invalid combination is given.
+     */
+    std::string GetChainName() const;
+
+    /**
+     * Add argument
+     */
+    void AddArg(const std::string& name, const std::string& help, unsigned int flags, const OptionsCategory& cat);
+
+    /**
+     * Add subcommand
+     */
+    void AddCommand(const std::string& cmd, const std::string& help);
+
+    /**
+     * Add many hidden arguments
+     */
+    void AddHiddenArgs(const std::vector<std::string>& args);
+
+    /**
+     * Clear available arguments
+     */
+    void ClearArgs() {
+        LOCK(cs_args);
+        m_available_args.clear();
+        m_network_only_args.clear();
+    }
+
+    /**
+     * Get the help string
+     */
+    std::string GetHelpMessage() const;
+
+    /**
+     * Return Flags for known arg.
+     * Return nullopt for unknown arg.
+     */
+    std::optional<unsigned int> GetArgFlags(const std::string& name) const;
+
+    /**
+     * Read and update settings file with saved settings. This needs to be
+     * called after SelectParams() because the settings file location is
+     * network-specific.
+     */
+    bool InitSettings(std::string& error);
+
+    /**
+     * Get settings file path, or return false if read-write settings were
+     * disabled with -nosettings.
+     */
+    bool GetSettingsPath(fs::path* filepath = nullptr, bool temp = false) const;
+
+    /**
+     * Read settings file. Push errors to vector, or log them if null.
+     */
+    bool ReadSettingsFile(std::vector<std::string>* errors = nullptr);
+
+    /**
+     * Write settings file. Push errors to vector, or log them if null.
+     */
+    bool WriteSettingsFile(std::vector<std::string>* errors = nullptr) const;
+
+    /**
+     * Access settings with lock held.
+     */
+    template <typename Fn>
+    void LockSettings(Fn&& fn)
+    {
+        LOCK(cs_args);
+        fn(m_settings);
+    }
+
+    /**
+     * Log the config file options and the command line arguments,
+     * useful for troubleshooting.
+     */
+    void LogArgs() const;
+
+private:
+    /**
+     * Get data directory path
+     *
+     * @param net_specific Append network identifier to the returned path
+     * @return Absolute path on success, otherwise an empty path when a non-directory path would be returned
+     * @post Returned directory path is created unless it is empty
+     */
+    const fs::path& GetDataDir(bool net_specific) const;
+
+    // Helper function for LogArgs().
+    void logArgsPrefix(
+        const std::string& prefix,
+        const std::string& section,
+        const std::map<std::string, std::vector<util::SettingsValue>>& args) const;
+};
+
+extern ArgsManager gArgs;
+
+/**
+ * @return true if help has been requested via a command-line arg
+ */
+bool HelpRequested(const ArgsManager& args);
+
+/** Add help options to the args manager */
+void SetupHelpOptions(ArgsManager& args);
+
+/**
+ * Format a string to be used as group of options in help messages
+ *
+ * @param message Group name (e.g. "RPC server options:")
+ * @return the formatted string
+ */
+std::string HelpMessageGroup(const std::string& message);
+
+/**
+ * Format a string to be used as option description in help messages
+ *
+ * @param option Option message (e.g. "-rpcuser=<user>")
+ * @param message Option description (e.g. "Username for JSON-RPC connections")
+ * @return the formatted string
+ */
+std::string HelpMessageOpt(const std::string& option, const std::string& message);
+
+/**
+ * Return the number of cores available on the current system.
+ * @note This does count virtual cores, such as those provided by HyperThreading.
+ */
+int GetNumCores();
+
+std::string CopyrightHolders(const std::string& strPrefix);
+
+/**
+ * On platforms that support it, tell the kernel the calling thread is
+ * CPU-intensive and non-interactive. See SCHED_BATCH in sched(7) for details.
+ *
+ */
+void ScheduleBatchPriority();
+
+namespace util {
+
+//! Simplification of std insertion
+template <typename Tdst, typename Tsrc>
+inline void insert(Tdst& dst, const Tsrc& src) {
+    dst.insert(dst.begin(), src.begin(), src.end());
+}
+template <typename TsetT, typename Tsrc>
+inline void insert(std::set<TsetT>& dst, const Tsrc& src) {
+    dst.insert(src.begin(), src.end());
+}
+
+/**
+ * Helper function to access the contained object of a std::any instance.
+ * Returns a pointer to the object if passed instance has a value and the type
+ * matches, nullptr otherwise.
+ */
+template<typename T>
+T* AnyPtr(const std::any& any) noexcept
+{
+    T* const* ptr = std::any_cast<T*>(&any);
+    return ptr ? *ptr : nullptr;
+}
+
+#ifdef WIN32
+class WinCmdLineArgs
+{
+public:
+    WinCmdLineArgs();
+    ~WinCmdLineArgs();
+    std::pair<int, char**> get();
+
+private:
+    int argc;
+    char** argv;
+    std::vector<std::string> args;
+};
+#endif
+
+} // namespace util
+
+#endif // DIGIBYTE_UTIL_SYSTEM_H

src/util/thread.cpp

@@ -0,0 +1,27 @@
+// Copyright (c) 2021 The DigiByte Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include <util/thread.h>
+
+#include <logging.h>
+#include <util/system.h>
+#include <util/threadnames.h>
+
+#include <exception>
+
+void util::TraceThread(const char* thread_name, std::function<void()> thread_func)
+{
+    util::ThreadRename(thread_name);
+    try {
+        LogPrintf("%s thread start\n", thread_name);
+        thread_func();
+        LogPrintf("%s thread exit\n", thread_name);
+    } catch (const std::exception& e) {
+        PrintExceptionContinue(&e, thread_name);
+        throw;
+    } catch (...) {
+        PrintExceptionContinue(nullptr, thread_name);
+        throw;
+    }
+}

src/util/thread.h

@@ -0,0 +1,18 @@
+// Copyright (c) 2021 The DigiByte Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef DIGIBYTE_UTIL_THREAD_H
+#define DIGIBYTE_UTIL_THREAD_H
+
+#include <functional>
+
+namespace util {
+/**
+ * A wrapper for do-something-once thread functions.
+ */
+void TraceThread(const char* thread_name, std::function<void()> thread_func);
+
+} // namespace util
+
+#endif // DIGIBYTE_UTIL_THREAD_H

src/util/threadnames.cpp

@@ -0,0 +1,66 @@
+// Copyright (c) 2018-2019 The DigiByte Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#if defined(HAVE_CONFIG_H)
+#include <config/vexta-config.h>
+#endif
+
+#include <thread>
+
+#if (defined(__FreeBSD__) || defined(__OpenBSD__) || defined(__DragonFly__))
+#include <pthread.h>
+#include <pthread_np.h>
+#endif
+
+#include <util/threadnames.h>
+
+#ifdef HAVE_SYS_PRCTL_H
+#include <sys/prctl.h> // For prctl, PR_SET_NAME, PR_GET_NAME
+#endif
+
+//! Set the thread's name at the process level. Does not affect the
+//! internal name.
+static void SetThreadName(const char* name)
+{
+#if defined(PR_SET_NAME)
+    // Only the first 15 characters are used (16 - NUL terminator)
+    ::prctl(PR_SET_NAME, name, 0, 0, 0);
+#elif (defined(__FreeBSD__) || defined(__OpenBSD__) || defined(__DragonFly__))
+    pthread_set_name_np(pthread_self(), name);
+#elif defined(MAC_OSX)
+    pthread_setname_np(name);
+#else
+    // Prevent warnings for unused parameters...
+    (void)name;
+#endif
+}
+
+// If we have thread_local, just keep thread ID and name in a thread_local
+// global.
+#if defined(HAVE_THREAD_LOCAL)
+
+static thread_local std::string g_thread_name;
+const std::string& util::ThreadGetInternalName() { return g_thread_name; }
+//! Set the in-memory internal name for this thread. Does not affect the process
+//! name.
+static void SetInternalName(std::string name) { g_thread_name = std::move(name); }
+
+// Without thread_local available, don't handle internal name at all.
+#else
+
+static const std::string empty_string;
+const std::string& util::ThreadGetInternalName() { return empty_string; }
+static void SetInternalName(std::string name) { }
+#endif
+
+void util::ThreadRename(std::string&& name)
+{
+    SetThreadName(("b-" + name).c_str());
+    SetInternalName(std::move(name));
+}
+
+void util::ThreadSetInternalName(std::string&& name)
+{
+    SetInternalName(std::move(name));
+}

src/util/threadnames.h

@@ -0,0 +1,26 @@
+// Copyright (c) 2018-2019 The DigiByte Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef DIGIBYTE_UTIL_THREADNAMES_H
+#define DIGIBYTE_UTIL_THREADNAMES_H
+
+#include <string>
+
+namespace util {
+//! Rename a thread both in terms of an internal (in-memory) name as well
+//! as its system thread name.
+//! @note Do not call this for the main thread, as this will interfere with
+//! UNIX utilities such as top and killall. Use ThreadSetInternalName instead.
+void ThreadRename(std::string&&);
+
+//! Set the internal (in-memory) name of the current thread only.
+void ThreadSetInternalName(std::string&&);
+
+//! Get the thread's internal (in-memory) name; used e.g. for identification in
+//! logging.
+const std::string& ThreadGetInternalName();
+
+} // namespace util
+
+#endif // DIGIBYTE_UTIL_THREADNAMES_H

src/util/time.cpp

@@ -0,0 +1,183 @@
+// Copyright (c) 2009-2010 Satoshi Nakamoto
+// Copyright (c) 2009-2020 The DigiByte Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#if defined(HAVE_CONFIG_H)
+#include <config/vexta-config.h>
+#endif
+
+#include <compat.h>
+#include <util/time.h>
+
+#include <util/check.h>
+
+#include <atomic>
+#include <boost/date_time/posix_time/posix_time.hpp>
+#include <ctime>
+#include <thread>
+
+#include <tinyformat.h>
+
+void UninterruptibleSleep(const std::chrono::microseconds& n) { std::this_thread::sleep_for(n); }
+
+static std::atomic<int64_t> nMockTime(0); //!< For testing
+
+int64_t GetTime()
+{
+    int64_t mocktime = nMockTime.load(std::memory_order_relaxed);
+    if (mocktime) return mocktime;
+
+    time_t now = time(nullptr);
+    assert(now > 0);
+    return now;
+}
+
+bool ChronoSanityCheck()
+{
+    // std::chrono::system_clock.time_since_epoch and time_t(0) are not guaranteed
+    // to use the Unix epoch timestamp, prior to C++20, but in practice they almost
+    // certainly will. Any differing behavior will be assumed to be an error, unless
+    // certain platforms prove to consistently deviate, at which point we'll cope
+    // with it by adding offsets.
+
+    // Create a new clock from time_t(0) and make sure that it represents 0
+    // seconds from the system_clock's time_since_epoch. Then convert that back
+    // to a time_t and verify that it's the same as before.
+    const time_t time_t_epoch{};
+    auto clock = std::chrono::system_clock::from_time_t(time_t_epoch);
+    if (std::chrono::duration_cast<std::chrono::seconds>(clock.time_since_epoch()).count() != 0) {
+        return false;
+    }
+
+    time_t time_val = std::chrono::system_clock::to_time_t(clock);
+    if (time_val != time_t_epoch) {
+        return false;
+    }
+
+    // Check that the above zero time is actually equal to the known unix timestamp.
+    struct tm epoch;
+#ifdef HAVE_GMTIME_R
+    if (gmtime_r(&time_val, &epoch) == nullptr) {
+#else
+    if (gmtime_s(&epoch, &time_val) != 0) {
+#endif
+        return false;
+    }
+
+    if ((epoch.tm_sec != 0)  ||
+       (epoch.tm_min  != 0)  ||
+       (epoch.tm_hour != 0)  ||
+       (epoch.tm_mday != 1)  ||
+       (epoch.tm_mon  != 0)  ||
+       (epoch.tm_year != 70)) {
+        return false;
+    }
+    return true;
+}
+
+template <typename T>
+T GetTime()
+{
+    const std::chrono::seconds mocktime{nMockTime.load(std::memory_order_relaxed)};
+
+    return std::chrono::duration_cast<T>(
+        mocktime.count() ?
+            mocktime :
+            std::chrono::microseconds{GetTimeMicros()});
+}
+template std::chrono::seconds GetTime();
+template std::chrono::milliseconds GetTime();
+template std::chrono::microseconds GetTime();
+
+template <typename T>
+static T GetSystemTime()
+{
+    const auto now = std::chrono::duration_cast<T>(std::chrono::system_clock::now().time_since_epoch());
+    assert(now.count() > 0);
+    return now;
+}
+
+void SetMockTime(int64_t nMockTimeIn)
+{
+    Assert(nMockTimeIn >= 0);
+    nMockTime.store(nMockTimeIn, std::memory_order_relaxed);
+}
+
+void SetMockTime(std::chrono::seconds mock_time_in)
+{
+    nMockTime.store(mock_time_in.count(), std::memory_order_relaxed);
+}
+
+std::chrono::seconds GetMockTime()
+{
+    return std::chrono::seconds(nMockTime.load(std::memory_order_relaxed));
+}
+
+int64_t GetTimeMillis()
+{
+    return int64_t{GetSystemTime<std::chrono::milliseconds>().count()};
+}
+
+int64_t GetTimeMicros()
+{
+    return int64_t{GetSystemTime<std::chrono::microseconds>().count()};
+}
+
+int64_t GetTimeSeconds()
+{
+    return int64_t{GetSystemTime<std::chrono::seconds>().count()};
+}
+
+std::string FormatISO8601DateTime(int64_t nTime) {
+    struct tm ts;
+    time_t time_val = nTime;
+#ifdef HAVE_GMTIME_R
+    if (gmtime_r(&time_val, &ts) == nullptr) {
+#else
+    if (gmtime_s(&ts, &time_val) != 0) {
+#endif
+        return {};
+    }
+    return strprintf("%04i-%02i-%02iT%02i:%02i:%02iZ", ts.tm_year + 1900, ts.tm_mon + 1, ts.tm_mday, ts.tm_hour, ts.tm_min, ts.tm_sec);
+}
+
+std::string FormatISO8601Date(int64_t nTime) {
+    struct tm ts;
+    time_t time_val = nTime;
+#ifdef HAVE_GMTIME_R
+    if (gmtime_r(&time_val, &ts) == nullptr) {
+#else
+    if (gmtime_s(&ts, &time_val) != 0) {
+#endif
+        return {};
+    }
+    return strprintf("%04i-%02i-%02i", ts.tm_year + 1900, ts.tm_mon + 1, ts.tm_mday);
+}
+
+int64_t ParseISO8601DateTime(const std::string& str)
+{
+    static const boost::posix_time::ptime epoch = boost::posix_time::from_time_t(0);
+    static const std::locale loc(std::locale::classic(),
+        new boost::posix_time::time_input_facet("%Y-%m-%dT%H:%M:%SZ"));
+    std::istringstream iss(str);
+    iss.imbue(loc);
+    boost::posix_time::ptime ptime(boost::date_time::not_a_date_time);
+    iss >> ptime;
+    if (ptime.is_not_a_date_time() || epoch > ptime)
+        return 0;
+    return (ptime - epoch).total_seconds();
+}
+
+struct timeval MillisToTimeval(int64_t nTimeout)
+{
+    struct timeval timeout;
+    timeout.tv_sec  = nTimeout / 1000;
+    timeout.tv_usec = (nTimeout % 1000) * 1000;
+    return timeout;
+}
+
+struct timeval MillisToTimeval(std::chrono::milliseconds ms)
+{
+    return MillisToTimeval(count_milliseconds(ms));
+}

src/util/time.h

@@ -0,0 +1,92 @@
+// Copyright (c) 2009-2010 Satoshi Nakamoto
+// Copyright (c) 2009-2020 The DigiByte Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef DIGIBYTE_UTIL_TIME_H
+#define DIGIBYTE_UTIL_TIME_H
+
+#include <compat.h>
+
+#include <chrono>
+#include <stdint.h>
+#include <string>
+
+using namespace std::chrono_literals;
+
+void UninterruptibleSleep(const std::chrono::microseconds& n);
+
+/**
+ * Helper to count the seconds of a duration.
+ *
+ * All durations should be using std::chrono and calling this should generally
+ * be avoided in code. Though, it is still preferred to an inline t.count() to
+ * protect against a reliance on the exact type of t.
+ *
+ * This helper is used to convert durations before passing them over an
+ * interface that doesn't support std::chrono (e.g. RPC, debug log, or the GUI)
+ */
+constexpr int64_t count_seconds(std::chrono::seconds t) { return t.count(); }
+constexpr int64_t count_milliseconds(std::chrono::milliseconds t) { return t.count(); }
+constexpr int64_t count_microseconds(std::chrono::microseconds t) { return t.count(); }
+
+using SecondsDouble = std::chrono::duration<double, std::chrono::seconds::period>;
+
+/**
+ * Helper to count the seconds in any std::chrono::duration type
+ */
+inline double CountSecondsDouble(SecondsDouble t) { return t.count(); }
+
+/**
+ * DEPRECATED
+ * Use either GetTimeSeconds (not mockable) or GetTime<T> (mockable)
+ */
+int64_t GetTime();
+
+/** Returns the system time (not mockable) */
+int64_t GetTimeMillis();
+/** Returns the system time (not mockable) */
+int64_t GetTimeMicros();
+/** Returns the system time (not mockable) */
+int64_t GetTimeSeconds(); // Like GetTime(), but not mockable
+
+/**
+ * DEPRECATED
+ * Use SetMockTime with chrono type
+ *
+ * @param[in] nMockTimeIn Time in seconds.
+ */
+void SetMockTime(int64_t nMockTimeIn);
+
+/** For testing. Set e.g. with the setmocktime rpc, or -mocktime argument */
+void SetMockTime(std::chrono::seconds mock_time_in);
+
+/** For testing */
+std::chrono::seconds GetMockTime();
+
+/** Return system time (or mocked time, if set) */
+template <typename T>
+T GetTime();
+
+/**
+ * ISO 8601 formatting is preferred. Use the FormatISO8601{DateTime,Date}
+ * helper functions if possible.
+ */
+std::string FormatISO8601DateTime(int64_t nTime);
+std::string FormatISO8601Date(int64_t nTime);
+int64_t ParseISO8601DateTime(const std::string& str);
+
+/**
+ * Convert milliseconds to a struct timeval for e.g. select.
+ */
+struct timeval MillisToTimeval(int64_t nTimeout);
+
+/**
+ * Convert milliseconds to a struct timeval for e.g. select.
+ */
+struct timeval MillisToTimeval(std::chrono::milliseconds ms);
+
+/** Sanity check epoch match normal Unix epoch */
+bool ChronoSanityCheck();
+
+#endif // DIGIBYTE_UTIL_TIME_H

src/util/tokenpipe.cpp

@@ -0,0 +1,109 @@
+// Copyright (c) 2021 The DigiByte Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+#include <util/tokenpipe.h>
+
+#include <config/vexta-config.h>
+
+#ifndef WIN32
+
+#include <errno.h>
+#include <fcntl.h>
+#include <optional>
+#include <unistd.h>
+
+TokenPipeEnd TokenPipe::TakeReadEnd()
+{
+    TokenPipeEnd res(m_fds[0]);
+    m_fds[0] = -1;
+    return res;
+}
+
+TokenPipeEnd TokenPipe::TakeWriteEnd()
+{
+    TokenPipeEnd res(m_fds[1]);
+    m_fds[1] = -1;
+    return res;
+}
+
+TokenPipeEnd::TokenPipeEnd(int fd) : m_fd(fd)
+{
+}
+
+TokenPipeEnd::~TokenPipeEnd()
+{
+    Close();
+}
+
+int TokenPipeEnd::TokenWrite(uint8_t token)
+{
+    while (true) {
+        ssize_t result = write(m_fd, &token, 1);
+        if (result < 0) {
+            // Failure. It's possible that the write was interrupted by a signal,
+            // in that case retry.
+            if (errno != EINTR) {
+                return TS_ERR;
+            }
+        } else if (result == 0) {
+            return TS_EOS;
+        } else { // ==1
+            return 0;
+        }
+    }
+}
+
+int TokenPipeEnd::TokenRead()
+{
+    uint8_t token;
+    while (true) {
+        ssize_t result = read(m_fd, &token, 1);
+        if (result < 0) {
+            // Failure. Check if the read was interrupted by a signal,
+            // in that case retry.
+            if (errno != EINTR) {
+                return TS_ERR;
+            }
+        } else if (result == 0) {
+            return TS_EOS;
+        } else { // ==1
+            return token;
+        }
+    }
+    return token;
+}
+
+void TokenPipeEnd::Close()
+{
+    if (m_fd != -1) close(m_fd);
+    m_fd = -1;
+}
+
+std::optional<TokenPipe> TokenPipe::Make()
+{
+    int fds[2] = {-1, -1};
+#if HAVE_O_CLOEXEC && HAVE_DECL_PIPE2
+    if (pipe2(fds, O_CLOEXEC) != 0) {
+        return std::nullopt;
+    }
+#else
+    if (pipe(fds) != 0) {
+        return std::nullopt;
+    }
+#endif
+    return TokenPipe(fds);
+}
+
+TokenPipe::~TokenPipe()
+{
+    Close();
+}
+
+void TokenPipe::Close()
+{
+    if (m_fds[0] != -1) close(m_fds[0]);
+    if (m_fds[1] != -1) close(m_fds[1]);
+    m_fds[0] = m_fds[1] = -1;
+}
+
+#endif // WIN32

src/util/tokenpipe.h

@@ -0,0 +1,127 @@
+// Copyright (c) 2021 The DigiByte Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef DIGIBYTE_UTIL_TOKENPIPE_H
+#define DIGIBYTE_UTIL_TOKENPIPE_H
+
+#ifndef WIN32
+
+#include <cstdint>
+#include <optional>
+
+/** One end of a token pipe. */
+class TokenPipeEnd
+{
+private:
+    int m_fd = -1;
+
+public:
+    TokenPipeEnd(int fd = -1);
+    ~TokenPipeEnd();
+
+    /** Return value constants for TokenWrite and TokenRead. */
+    enum Status {
+        TS_ERR = -1, //!< I/O error
+        TS_EOS = -2, //!< Unexpected end of stream
+    };
+
+    /** Write token to endpoint.
+     *
+     * @returns 0       If successful.
+     *          <0 if error:
+     *            TS_ERR  If an error happened.
+     *            TS_EOS  If end of stream happened.
+     */
+    int TokenWrite(uint8_t token);
+
+    /** Read token from endpoint.
+     *
+     * @returns >=0     Token value, if successful.
+     *          <0 if error:
+     *            TS_ERR  If an error happened.
+     *            TS_EOS  If end of stream happened.
+     */
+    int TokenRead();
+
+    /** Explicit close function.
+     */
+    void Close();
+
+    /** Return whether endpoint is open.
+     */
+    bool IsOpen() { return m_fd != -1; }
+
+    // Move-only class.
+    TokenPipeEnd(TokenPipeEnd&& other)
+    {
+        m_fd = other.m_fd;
+        other.m_fd = -1;
+    }
+    TokenPipeEnd& operator=(TokenPipeEnd&& other)
+    {
+        Close();
+        m_fd = other.m_fd;
+        other.m_fd = -1;
+        return *this;
+    }
+    TokenPipeEnd(const TokenPipeEnd&) = delete;
+    TokenPipeEnd& operator=(const TokenPipeEnd&) = delete;
+};
+
+/** An interprocess or interthread pipe for sending tokens (one-byte values)
+ * over.
+ */
+class TokenPipe
+{
+private:
+    int m_fds[2] = {-1, -1};
+
+    TokenPipe(int fds[2]) : m_fds{fds[0], fds[1]} {}
+
+public:
+    ~TokenPipe();
+
+    /** Create a new pipe.
+     * @returns The created TokenPipe, or an empty std::nullopt in case of error.
+     */
+    static std::optional<TokenPipe> Make();
+
+    /** Take the read end of this pipe. This can only be called once,
+     * as the object will be moved out.
+     */
+    TokenPipeEnd TakeReadEnd();
+
+    /** Take the write end of this pipe. This should only be called once,
+     * as the object will be moved out.
+     */
+    TokenPipeEnd TakeWriteEnd();
+
+    /** Close and end of the pipe that hasn't been moved out.
+     */
+    void Close();
+
+    // Move-only class.
+    TokenPipe(TokenPipe&& other)
+    {
+        for (int i = 0; i < 2; ++i) {
+            m_fds[i] = other.m_fds[i];
+            other.m_fds[i] = -1;
+        }
+    }
+    TokenPipe& operator=(TokenPipe&& other)
+    {
+        Close();
+        for (int i = 0; i < 2; ++i) {
+            m_fds[i] = other.m_fds[i];
+            other.m_fds[i] = -1;
+        }
+        return *this;
+    }
+    TokenPipe(const TokenPipe&) = delete;
+    TokenPipe& operator=(const TokenPipe&) = delete;
+};
+
+#endif // WIN32
+
+#endif // DIGIBYTE_UTIL_TOKENPIPE_H

src/util/trace.h

@@ -0,0 +1,45 @@
+// Copyright (c) 2020 The DigiByte Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef DIGIBYTE_UTIL_TRACE_H
+#define DIGIBYTE_UTIL_TRACE_H
+
+#ifdef ENABLE_TRACING
+
+#include <sys/sdt.h>
+
+#define TRACE(context, event) DTRACE_PROBE(context, event)
+#define TRACE1(context, event, a) DTRACE_PROBE1(context, event, a)
+#define TRACE2(context, event, a, b) DTRACE_PROBE2(context, event, a, b)
+#define TRACE3(context, event, a, b, c) DTRACE_PROBE3(context, event, a, b, c)
+#define TRACE4(context, event, a, b, c, d) DTRACE_PROBE4(context, event, a, b, c, d)
+#define TRACE5(context, event, a, b, c, d, e) DTRACE_PROBE5(context, event, a, b, c, d, e)
+#define TRACE6(context, event, a, b, c, d, e, f) DTRACE_PROBE6(context, event, a, b, c, d, e, f)
+#define TRACE7(context, event, a, b, c, d, e, f, g) DTRACE_PROBE7(context, event, a, b, c, d, e, f, g)
+#define TRACE8(context, event, a, b, c, d, e, f, g, h) DTRACE_PROBE8(context, event, a, b, c, d, e, f, g, h)
+#define TRACE9(context, event, a, b, c, d, e, f, g, h, i) DTRACE_PROBE9(context, event, a, b, c, d, e, f, g, h, i)
+#define TRACE10(context, event, a, b, c, d, e, f, g, h, i, j) DTRACE_PROBE10(context, event, a, b, c, d, e, f, g, h, i, j)
+#define TRACE11(context, event, a, b, c, d, e, f, g, h, i, j, k) DTRACE_PROBE11(context, event, a, b, c, d, e, f, g, h, i, j, k)
+#define TRACE12(context, event, a, b, c, d, e, f, g, h, i, j, k, l) DTRACE_PROBE12(context, event, a, b, c, d, e, f, g, h, i, j, k, l)
+
+#else
+
+#define TRACE(context, event)
+#define TRACE1(context, event, a)
+#define TRACE2(context, event, a, b)
+#define TRACE3(context, event, a, b, c)
+#define TRACE4(context, event, a, b, c, d)
+#define TRACE5(context, event, a, b, c, d, e)
+#define TRACE6(context, event, a, b, c, d, e, f)
+#define TRACE7(context, event, a, b, c, d, e, f, g)
+#define TRACE8(context, event, a, b, c, d, e, f, g, h)
+#define TRACE9(context, event, a, b, c, d, e, f, g, h, i)
+#define TRACE10(context, event, a, b, c, d, e, f, g, h, i, j)
+#define TRACE11(context, event, a, b, c, d, e, f, g, h, i, j, k)
+#define TRACE12(context, event, a, b, c, d, e, f, g, h, i, j, k, l)
+
+#endif
+
+
+#endif /* DIGIBYTE_UTIL_TRACE_H */

src/util/translation.h

@@ -0,0 +1,62 @@
+// Copyright (c) 2019-2020 The DigiByte Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef DIGIBYTE_UTIL_TRANSLATION_H
+#define DIGIBYTE_UTIL_TRANSLATION_H
+
+#include <tinyformat.h>
+#include <functional>
+
+/**
+ * Bilingual messages:
+ *   - in GUI: user's native language + untranslated (i.e. English)
+ *   - in log and stderr: untranslated only
+ */
+struct bilingual_str {
+    std::string original;
+    std::string translated;
+
+    bilingual_str& operator+=(const bilingual_str& rhs)
+    {
+        original += rhs.original;
+        translated += rhs.translated;
+        return *this;
+    }
+
+    bool empty() const
+    {
+        return original.empty();
+    }
+};
+
+inline bilingual_str operator+(bilingual_str lhs, const bilingual_str& rhs)
+{
+    lhs += rhs;
+    return lhs;
+}
+
+/** Mark a bilingual_str as untranslated */
+inline bilingual_str Untranslated(std::string original) { return {original, original}; }
+
+namespace tinyformat {
+template <typename... Args>
+bilingual_str format(const bilingual_str& fmt, const Args&... args)
+{
+    return bilingual_str{format(fmt.original, args...), format(fmt.translated, args...)};
+}
+} // namespace tinyformat
+
+/** Translate a message to the native language of the user. */
+const extern std::function<std::string(const char*)> G_TRANSLATION_FUN;
+
+/**
+ * Translation function.
+ * If no translation function is set, simply return the input.
+ */
+inline bilingual_str _(const char* psz)
+{
+    return bilingual_str{psz, G_TRANSLATION_FUN ? (G_TRANSLATION_FUN)(psz) : psz};
+}
+
+#endif // DIGIBYTE_UTIL_TRANSLATION_H

src/util/ui_change_type.h

@@ -0,0 +1,15 @@
+// Copyright (c) 2012-2020 The DigiByte Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef DIGIBYTE_UTIL_UI_CHANGE_TYPE_H
+#define DIGIBYTE_UTIL_UI_CHANGE_TYPE_H
+
+/** General change type (added, updated, removed). */
+enum ChangeType {
+    CT_NEW,
+    CT_UPDATED,
+    CT_DELETED
+};
+
+#endif // DIGIBYTE_UTIL_UI_CHANGE_TYPE_H

src/util/url.cpp

@@ -0,0 +1,21 @@
+// Copyright (c) 2015-2019 The DigiByte Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include <util/url.h>
+
+#include <event2/http.h>
+#include <stdlib.h>
+#include <string>
+
+std::string urlDecode(const std::string &urlEncoded) {
+    std::string res;
+    if (!urlEncoded.empty()) {
+        char *decoded = evhttp_uridecode(urlEncoded.c_str(), false, nullptr);
+        if (decoded) {
+            res = std::string(decoded);
+            free(decoded);
+        }
+    }
+    return res;
+}

src/util/url.h

@@ -0,0 +1,14 @@
+// Copyright (c) 2015-2020 The DigiByte Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef DIGIBYTE_UTIL_URL_H
+#define DIGIBYTE_UTIL_URL_H
+
+#include <string>
+
+using UrlDecodeFn = std::string(const std::string& url_encoded);
+UrlDecodeFn urlDecode;
+extern UrlDecodeFn* const URL_DECODE;
+
+#endif // DIGIBYTE_UTIL_URL_H

src/util/vector.h

@@ -0,0 +1,51 @@
+// Copyright (c) 2019 The DigiByte Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef DIGIBYTE_UTIL_VECTOR_H
+#define DIGIBYTE_UTIL_VECTOR_H
+
+#include <initializer_list>
+#include <type_traits>
+#include <vector>
+
+/** Construct a vector with the specified elements.
+ *
+ * This is preferable over the list initializing constructor of std::vector:
+ * - It automatically infers the element type from its arguments.
+ * - If any arguments are rvalue references, they will be moved into the vector
+ *   (list initialization always copies).
+ */
+template<typename... Args>
+inline std::vector<typename std::common_type<Args...>::type> Vector(Args&&... args)
+{
+    std::vector<typename std::common_type<Args...>::type> ret;
+    ret.reserve(sizeof...(args));
+    // The line below uses the trick from https://www.experts-exchange.com/articles/32502/None-recursive-variadic-templates-with-std-initializer-list.html
+    (void)std::initializer_list<int>{(ret.emplace_back(std::forward<Args>(args)), 0)...};
+    return ret;
+}
+
+/** Concatenate two vectors, moving elements. */
+template<typename V>
+inline V Cat(V v1, V&& v2)
+{
+    v1.reserve(v1.size() + v2.size());
+    for (auto& arg : v2) {
+        v1.push_back(std::move(arg));
+    }
+    return v1;
+}
+
+/** Concatenate two vectors. */
+template<typename V>
+inline V Cat(V v1, const V& v2)
+{
+    v1.reserve(v1.size() + v2.size());
+    for (const auto& arg : v2) {
+        v1.push_back(arg);
+    }
+    return v1;
+}
+
+#endif // DIGIBYTE_UTIL_VECTOR_H