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src/util/asmap.cpp
// Copyright (c) 2019 The Bitcoin Core developers | // Copyright (c) 2019 The Bitcoin Core developers | ||||
// Distributed under the MIT software license, see the accompanying | // Distributed under the MIT software license, see the accompanying | ||||
// file COPYING or http://www.opensource.org/licenses/mit-license.php. | // file COPYING or http://www.opensource.org/licenses/mit-license.php. | ||||
#include <crypto/common.h> | #include <crypto/common.h> | ||||
#include <cassert> | #include <cassert> | ||||
#include <vector> | #include <vector> | ||||
namespace { | namespace { | ||||
uint32_t DecodeBits(std::vector<bool>::const_iterator &bitpos, uint8_t minval, | uint32_t DecodeBits(std::vector<bool>::const_iterator &bitpos, | ||||
const std::vector<uint8_t> &bit_sizes) { | const std::vector<bool>::const_iterator &endpos, | ||||
uint8_t minval, const std::vector<uint8_t> &bit_sizes) { | |||||
uint32_t val = minval; | uint32_t val = minval; | ||||
bool bit; | bool bit; | ||||
for (std::vector<uint8_t>::const_iterator bit_sizes_it = bit_sizes.begin(); | for (std::vector<uint8_t>::const_iterator bit_sizes_it = bit_sizes.begin(); | ||||
bit_sizes_it != bit_sizes.end(); ++bit_sizes_it) { | bit_sizes_it != bit_sizes.end(); ++bit_sizes_it) { | ||||
if (bit_sizes_it + 1 != bit_sizes.end()) { | if (bit_sizes_it + 1 != bit_sizes.end()) { | ||||
if (bitpos == endpos) { | |||||
break; | |||||
} | |||||
bit = *bitpos; | bit = *bitpos; | ||||
bitpos++; | bitpos++; | ||||
} else { | } else { | ||||
bit = 0; | bit = 0; | ||||
} | } | ||||
if (bit) { | if (bit) { | ||||
val += (1 << *bit_sizes_it); | val += (1 << *bit_sizes_it); | ||||
} else { | } else { | ||||
for (int b = 0; b < *bit_sizes_it; b++) { | for (int b = 0; b < *bit_sizes_it; b++) { | ||||
if (bitpos == endpos) { | |||||
break; | |||||
} | |||||
bit = *bitpos; | bit = *bitpos; | ||||
bitpos++; | bitpos++; | ||||
val += bit << (*bit_sizes_it - 1 - b); | val += bit << (*bit_sizes_it - 1 - b); | ||||
} | } | ||||
return val; | return val; | ||||
} | } | ||||
} | } | ||||
return -1; | return -1; | ||||
} | } | ||||
const std::vector<uint8_t> TYPE_BIT_SIZES{0, 0, 1}; | const std::vector<uint8_t> TYPE_BIT_SIZES{0, 0, 1}; | ||||
uint32_t DecodeType(std::vector<bool>::const_iterator &bitpos) { | uint32_t DecodeType(std::vector<bool>::const_iterator &bitpos, | ||||
return DecodeBits(bitpos, 0, TYPE_BIT_SIZES); | const std::vector<bool>::const_iterator &endpos) { | ||||
return DecodeBits(bitpos, endpos, 0, TYPE_BIT_SIZES); | |||||
} | } | ||||
const std::vector<uint8_t> ASN_BIT_SIZES{15, 16, 17, 18, 19, | const std::vector<uint8_t> ASN_BIT_SIZES{15, 16, 17, 18, 19, | ||||
20, 21, 22, 23, 24}; | 20, 21, 22, 23, 24}; | ||||
uint32_t DecodeASN(std::vector<bool>::const_iterator &bitpos) { | uint32_t DecodeASN(std::vector<bool>::const_iterator &bitpos, | ||||
return DecodeBits(bitpos, 1, ASN_BIT_SIZES); | 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}; | 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) { | uint32_t DecodeMatch(std::vector<bool>::const_iterator &bitpos, | ||||
return DecodeBits(bitpos, 2, MATCH_BIT_SIZES); | 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, | 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, | 14, 15, 16, 17, 18, 19, 20, 21, 22, | ||||
23, 24, 25, 26, 27, 28, 29, 30}; | 23, 24, 25, 26, 27, 28, 29, 30}; | ||||
uint32_t DecodeJump(std::vector<bool>::const_iterator &bitpos) { | uint32_t DecodeJump(std::vector<bool>::const_iterator &bitpos, | ||||
return DecodeBits(bitpos, 17, JUMP_BIT_SIZES); | const std::vector<bool>::const_iterator &endpos) { | ||||
return DecodeBits(bitpos, endpos, 17, JUMP_BIT_SIZES); | |||||
} | } | ||||
} // namespace | } // namespace | ||||
uint32_t Interpret(const std::vector<bool> &asmap, | uint32_t Interpret(const std::vector<bool> &asmap, | ||||
const std::vector<bool> &ip) { | const std::vector<bool> &ip) { | ||||
std::vector<bool>::const_iterator pos = asmap.begin(); | std::vector<bool>::const_iterator pos = asmap.begin(); | ||||
const std::vector<bool>::const_iterator endpos = asmap.end(); | |||||
uint8_t bits = ip.size(); | uint8_t bits = ip.size(); | ||||
uint8_t default_asn = 0; | uint32_t default_asn = 0; | ||||
uint32_t opcode, jump, match, matchlen; | uint32_t opcode, jump, match, matchlen; | ||||
while (1) { | while (pos != endpos) { | ||||
assert(pos != asmap.end()); | opcode = DecodeType(pos, endpos); | ||||
opcode = DecodeType(pos); | |||||
if (opcode == 0) { | if (opcode == 0) { | ||||
return DecodeASN(pos); | return DecodeASN(pos, endpos); | ||||
} else if (opcode == 1) { | } else if (opcode == 1) { | ||||
jump = DecodeJump(pos); | jump = DecodeJump(pos, endpos); | ||||
if (bits == 0) { | |||||
break; | |||||
} | |||||
if (ip[ip.size() - bits]) { | if (ip[ip.size() - bits]) { | ||||
if (jump >= endpos - pos) { | |||||
break; | |||||
} | |||||
pos += jump; | pos += jump; | ||||
} | } | ||||
bits--; | bits--; | ||||
} else if (opcode == 2) { | } else if (opcode == 2) { | ||||
match = DecodeMatch(pos); | match = DecodeMatch(pos, endpos); | ||||
matchlen = CountBits(match) - 1; | matchlen = CountBits(match) - 1; | ||||
for (uint32_t bit = 0; bit < matchlen; bit++) { | for (uint32_t bit = 0; bit < matchlen; bit++) { | ||||
if (bits == 0) { | |||||
break; | |||||
} | |||||
if ((ip[ip.size() - bits]) != | if ((ip[ip.size() - bits]) != | ||||
((match >> (matchlen - 1 - bit)) & 1)) { | ((match >> (matchlen - 1 - bit)) & 1)) { | ||||
return default_asn; | return default_asn; | ||||
} | } | ||||
bits--; | bits--; | ||||
} | } | ||||
} else if (opcode == 3) { | } else if (opcode == 3) { | ||||
default_asn = DecodeASN(pos); | default_asn = DecodeASN(pos, endpos); | ||||
} else { | } else { | ||||
assert(0); | break; | ||||
} | } | ||||
} | } | ||||
// 0 is not a valid ASN | |||||
return 0; | |||||
} | } |