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# 1 : : // Copyright (c) 2019-2021 The Bitcoin Core developers
# 2 : : // Distributed under the MIT software license, see the accompanying
# 3 : : // file COPYING or http://www.opensource.org/licenses/mit-license.php.
# 4 : :
# 5 : : #include <util/asmap.h>
# 6 : :
# 7 : : #include <clientversion.h>
# 8 : : #include <crypto/common.h>
# 9 : : #include <fs.h>
# 10 : : #include <logging.h>
# 11 : : #include <streams.h>
# 12 : :
# 13 : : #include <cassert>
# 14 : : #include <map>
# 15 : : #include <vector>
# 16 : :
# 17 : : namespace {
# 18 : :
# 19 : : constexpr uint32_t INVALID = 0xFFFFFFFF;
# 20 : :
# 21 : : 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)
# 22 : 232504 : {
# 23 : 232504 : uint32_t val = minval;
# 24 : 232504 : bool bit;
# 25 : 232504 : for (std::vector<uint8_t>::const_iterator bit_sizes_it = bit_sizes.begin();
# 26 [ + - ]: 1158942 : bit_sizes_it != bit_sizes.end(); ++bit_sizes_it) {
# 27 [ + + ]: 1158942 : if (bit_sizes_it + 1 != bit_sizes.end()) {
# 28 [ - + ]: 958606 : if (bitpos == endpos) break;
# 29 : 958606 : bit = *bitpos;
# 30 : 958606 : bitpos++;
# 31 : 958606 : } else {
# 32 : 200336 : bit = 0;
# 33 : 200336 : }
# 34 [ + + ]: 1158942 : if (bit) {
# 35 : 926438 : val += (1 << *bit_sizes_it);
# 36 : 926438 : } else {
# 37 [ + + ]: 1302836 : for (int b = 0; b < *bit_sizes_it; b++) {
# 38 [ - + ]: 1070332 : if (bitpos == endpos) return INVALID; // Reached EOF in mantissa
# 39 : 1070332 : bit = *bitpos;
# 40 : 1070332 : bitpos++;
# 41 : 1070332 : val += bit << (*bit_sizes_it - 1 - b);
# 42 : 1070332 : }
# 43 : 232504 : return val;
# 44 : 232504 : }
# 45 : 1158942 : }
# 46 : 0 : return INVALID; // Reached EOF in exponent
# 47 : 232504 : }
# 48 : :
# 49 : : enum class Instruction : uint32_t
# 50 : : {
# 51 : : RETURN = 0,
# 52 : : JUMP = 1,
# 53 : : MATCH = 2,
# 54 : : DEFAULT = 3,
# 55 : : };
# 56 : :
# 57 : : const std::vector<uint8_t> TYPE_BIT_SIZES{0, 0, 1};
# 58 : : Instruction DecodeType(std::vector<bool>::const_iterator& bitpos, const std::vector<bool>::const_iterator& endpos)
# 59 : 116252 : {
# 60 : 116252 : return Instruction(DecodeBits(bitpos, endpos, 0, TYPE_BIT_SIZES));
# 61 : 116252 : }
# 62 : :
# 63 : : const std::vector<uint8_t> ASN_BIT_SIZES{15, 16, 17, 18, 19, 20, 21, 22, 23, 24};
# 64 : : uint32_t DecodeASN(std::vector<bool>::const_iterator& bitpos, const std::vector<bool>::const_iterator& endpos)
# 65 : 7330 : {
# 66 : 7330 : return DecodeBits(bitpos, endpos, 1, ASN_BIT_SIZES);
# 67 : 7330 : }
# 68 : :
# 69 : :
# 70 : : const std::vector<uint8_t> MATCH_BIT_SIZES{1, 2, 3, 4, 5, 6, 7, 8};
# 71 : : uint32_t DecodeMatch(std::vector<bool>::const_iterator& bitpos, const std::vector<bool>::const_iterator& endpos)
# 72 : 100436 : {
# 73 : 100436 : return DecodeBits(bitpos, endpos, 2, MATCH_BIT_SIZES);
# 74 : 100436 : }
# 75 : :
# 76 : :
# 77 : : 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};
# 78 : : uint32_t DecodeJump(std::vector<bool>::const_iterator& bitpos, const std::vector<bool>::const_iterator& endpos)
# 79 : 8486 : {
# 80 : 8486 : return DecodeBits(bitpos, endpos, 17, JUMP_BIT_SIZES);
# 81 : 8486 : }
# 82 : :
# 83 : : }
# 84 : :
# 85 : : uint32_t Interpret(const std::vector<bool> &asmap, const std::vector<bool> &ip)
# 86 : 8232 : {
# 87 : 8232 : std::vector<bool>::const_iterator pos = asmap.begin();
# 88 : 8232 : const std::vector<bool>::const_iterator endpos = asmap.end();
# 89 : 8232 : uint8_t bits = ip.size();
# 90 : 8232 : uint32_t default_asn = 0;
# 91 : 8232 : uint32_t jump, match, matchlen;
# 92 : 8232 : Instruction opcode;
# 93 [ + - ]: 116066 : while (pos != endpos) {
# 94 : 116066 : opcode = DecodeType(pos, endpos);
# 95 [ + + ]: 116066 : if (opcode == Instruction::RETURN) {
# 96 : 7276 : default_asn = DecodeASN(pos, endpos);
# 97 [ - + ]: 7276 : if (default_asn == INVALID) break; // ASN straddles EOF
# 98 : 7276 : return default_asn;
# 99 [ + + ]: 108790 : } else if (opcode == Instruction::JUMP) {
# 100 : 8438 : jump = DecodeJump(pos, endpos);
# 101 [ - + ]: 8438 : if (jump == INVALID) break; // Jump offset straddles EOF
# 102 [ - + ]: 8438 : if (bits == 0) break; // No input bits left
# 103 [ - + ]: 8438 : if (int64_t{jump} >= int64_t{endpos - pos}) break; // Jumping past EOF
# 104 [ + + ]: 8438 : if (ip[ip.size() - bits]) {
# 105 : 7270 : pos += jump;
# 106 : 7270 : }
# 107 : 8438 : bits--;
# 108 [ + - ]: 100352 : } else if (opcode == Instruction::MATCH) {
# 109 : 100352 : match = DecodeMatch(pos, endpos);
# 110 [ - + ]: 100352 : if (match == INVALID) break; // Match bits straddle EOF
# 111 : 100352 : matchlen = CountBits(match) - 1;
# 112 [ - + ]: 100352 : if (bits < matchlen) break; // Not enough input bits
# 113 [ + + ]: 898922 : for (uint32_t bit = 0; bit < matchlen; bit++) {
# 114 [ + + ]: 799526 : if ((ip[ip.size() - bits]) != ((match >> (matchlen - 1 - bit)) & 1)) {
# 115 : 956 : return default_asn;
# 116 : 956 : }
# 117 : 798570 : bits--;
# 118 : 798570 : }
# 119 [ # # ]: 100352 : } else if (opcode == Instruction::DEFAULT) {
# 120 : 0 : default_asn = DecodeASN(pos, endpos);
# 121 [ # # ]: 0 : if (default_asn == INVALID) break; // ASN straddles EOF
# 122 : 0 : } else {
# 123 : 0 : break; // Instruction straddles EOF
# 124 : 0 : }
# 125 : 116066 : }
# 126 : 0 : assert(false); // Reached EOF without RETURN, or aborted (see any of the breaks above) - should have been caught by SanityCheckASMap below
# 127 : 0 : return 0; // 0 is not a valid ASN
# 128 : 8232 : }
# 129 : :
# 130 : : bool SanityCheckASMap(const std::vector<bool>& asmap, int bits)
# 131 : 7 : {
# 132 : 7 : const std::vector<bool>::const_iterator begin = asmap.begin(), endpos = asmap.end();
# 133 : 7 : std::vector<bool>::const_iterator pos = begin;
# 134 : 7 : std::vector<std::pair<uint32_t, int>> jumps; // All future positions we may jump to (bit offset in asmap -> bits to consume left)
# 135 : 7 : jumps.reserve(bits);
# 136 : 7 : Instruction prevopcode = Instruction::JUMP;
# 137 : 7 : bool had_incomplete_match = false;
# 138 [ + + ]: 187 : while (pos != endpos) {
# 139 : 186 : uint32_t offset = pos - begin;
# 140 [ + + ][ - + ]: 186 : if (!jumps.empty() && offset >= jumps.back().first) return false; // There was a jump into the middle of the previous instruction
# 141 : 186 : Instruction opcode = DecodeType(pos, endpos);
# 142 [ + + ]: 186 : if (opcode == Instruction::RETURN) {
# 143 [ - + ]: 54 : if (prevopcode == Instruction::DEFAULT) return false; // There should not be any RETURN immediately after a DEFAULT (could be combined into just RETURN)
# 144 : 54 : uint32_t asn = DecodeASN(pos, endpos);
# 145 [ - + ]: 54 : if (asn == INVALID) return false; // ASN straddles EOF
# 146 [ + + ]: 54 : if (jumps.empty()) {
# 147 : : // Nothing to execute anymore
# 148 [ - + ]: 6 : if (endpos - pos > 7) return false; // Excessive padding
# 149 [ + + ]: 18 : while (pos != endpos) {
# 150 [ - + ]: 12 : if (*pos) return false; // Nonzero padding bit
# 151 : 12 : ++pos;
# 152 : 12 : }
# 153 : 6 : return true; // Sanely reached EOF
# 154 : 48 : } else {
# 155 : : // Continue by pretending we jumped to the next instruction
# 156 : 48 : offset = pos - begin;
# 157 [ - + ]: 48 : if (offset != jumps.back().first) return false; // Unreachable code
# 158 : 48 : bits = jumps.back().second; // Restore the number of bits we would have had left after this jump
# 159 : 48 : jumps.pop_back();
# 160 : 48 : prevopcode = Instruction::JUMP;
# 161 : 48 : }
# 162 [ + + ]: 132 : } else if (opcode == Instruction::JUMP) {
# 163 : 48 : uint32_t jump = DecodeJump(pos, endpos);
# 164 [ - + ]: 48 : if (jump == INVALID) return false; // Jump offset straddles EOF
# 165 [ - + ]: 48 : if (int64_t{jump} > int64_t{endpos - pos}) return false; // Jump out of range
# 166 [ - + ]: 48 : if (bits == 0) return false; // Consuming bits past the end of the input
# 167 : 48 : --bits;
# 168 : 48 : uint32_t jump_offset = pos - begin + jump;
# 169 [ + + ][ - + ]: 48 : if (!jumps.empty() && jump_offset >= jumps.back().first) return false; // Intersecting jumps
# 170 : 48 : jumps.emplace_back(jump_offset, bits);
# 171 : 48 : prevopcode = Instruction::JUMP;
# 172 [ + - ]: 84 : } else if (opcode == Instruction::MATCH) {
# 173 : 84 : uint32_t match = DecodeMatch(pos, endpos);
# 174 [ - + ]: 84 : if (match == INVALID) return false; // Match bits straddle EOF
# 175 : 84 : int matchlen = CountBits(match) - 1;
# 176 [ + + ]: 84 : if (prevopcode != Instruction::MATCH) had_incomplete_match = false;
# 177 [ + + ][ - + ]: 84 : if (matchlen < 8 && had_incomplete_match) return false; // Within a sequence of matches only at most one should be incomplete
# 178 : 84 : had_incomplete_match = (matchlen < 8);
# 179 [ - + ]: 84 : if (bits < matchlen) return false; // Consuming bits past the end of the input
# 180 : 84 : bits -= matchlen;
# 181 : 84 : prevopcode = Instruction::MATCH;
# 182 [ # # ]: 84 : } else if (opcode == Instruction::DEFAULT) {
# 183 [ # # ]: 0 : if (prevopcode == Instruction::DEFAULT) return false; // There should not be two successive DEFAULTs (they could be combined into one)
# 184 : 0 : uint32_t asn = DecodeASN(pos, endpos);
# 185 [ # # ]: 0 : if (asn == INVALID) return false; // ASN straddles EOF
# 186 : 0 : prevopcode = Instruction::DEFAULT;
# 187 : 0 : } else {
# 188 : 0 : return false; // Instruction straddles EOF
# 189 : 0 : }
# 190 : 186 : }
# 191 : 1 : return false; // Reached EOF without RETURN instruction
# 192 : 7 : }
# 193 : :
# 194 : : std::vector<bool> DecodeAsmap(fs::path path)
# 195 : 7 : {
# 196 : 7 : std::vector<bool> bits;
# 197 : 7 : FILE *filestr = fsbridge::fopen(path, "rb");
# 198 : 7 : CAutoFile file(filestr, SER_DISK, CLIENT_VERSION);
# 199 [ - + ]: 7 : if (file.IsNull()) {
# 200 : 0 : LogPrintf("Failed to open asmap file from disk\n");
# 201 : 0 : return bits;
# 202 : 0 : }
# 203 : 7 : fseek(filestr, 0, SEEK_END);
# 204 : 7 : int length = ftell(filestr);
# 205 : 7 : LogPrintf("Opened asmap file %s (%d bytes) from disk\n", fs::quoted(fs::PathToString(path)), length);
# 206 : 7 : fseek(filestr, 0, SEEK_SET);
# 207 : 7 : uint8_t cur_byte;
# 208 [ + + ]: 361 : for (int i = 0; i < length; ++i) {
# 209 : 354 : file >> cur_byte;
# 210 [ + + ]: 3186 : for (int bit = 0; bit < 8; ++bit) {
# 211 : 2832 : bits.push_back((cur_byte >> bit) & 1);
# 212 : 2832 : }
# 213 : 354 : }
# 214 [ + + ]: 7 : if (!SanityCheckASMap(bits, 128)) {
# 215 : 1 : LogPrintf("Sanity check of asmap file %s failed\n", fs::quoted(fs::PathToString(path)));
# 216 : 1 : return {};
# 217 : 1 : }
# 218 : 6 : return bits;
# 219 : 7 : }
# 220 : :
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