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// Copyright (c) 2021-2022 The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
#include <netgroup.h>
#include <hash.h>
#include <util/asmap.h>
uint256 NetGroupManager::GetAsmapChecksum() const
{
if (!m_asmap.size()) return {};
return (HashWriter{} << m_asmap).GetHash();
}
std::vector<unsigned char> NetGroupManager::GetGroup(const CNetAddr& address) const
{
std::vector<unsigned char> vchRet;
// If non-empty asmap is supplied and the address is IPv4/IPv6,
// return ASN to be used for bucketing.
uint32_t asn = GetMappedAS(address);
if (asn != 0) { // Either asmap was empty, or address has non-asmappable net class (e.g. TOR).
vchRet.push_back(NET_IPV6); // IPv4 and IPv6 with same ASN should be in the same bucket
for (int i = 0; i < 4; i++) {
vchRet.push_back((asn >> (8 * i)) & 0xFF);
}
return vchRet;
}
vchRet.push_back(address.GetNetClass());
int nStartByte{0};
int nBits{0};
if (address.IsLocal()) {
// all local addresses belong to the same group
} else if (address.IsInternal()) {
// All internal-usage addresses get their own group.
// Skip over the INTERNAL_IN_IPV6_PREFIX returned by CAddress::GetAddrBytes().
nStartByte = INTERNAL_IN_IPV6_PREFIX.size();
nBits = ADDR_INTERNAL_SIZE * 8;
} else if (!address.IsRoutable()) {
// all other unroutable addresses belong to the same group
} else if (address.HasLinkedIPv4()) {
// IPv4 addresses (and mapped IPv4 addresses) use /16 groups
uint32_t ipv4 = address.GetLinkedIPv4();
vchRet.push_back((ipv4 >> 24) & 0xFF);
vchRet.push_back((ipv4 >> 16) & 0xFF);
return vchRet;
} else if (address.IsTor() || address.IsI2P()) {
nBits = 4;
} else if (address.IsCJDNS()) {
// Treat in the same way as Tor and I2P because the address in all of
// them is "random" bytes (derived from a public key). However in CJDNS
// the first byte is a constant (see CJDNS_PREFIX), so the random bytes
// come after it. Thus skip the constant 8 bits at the start.
nBits = 12;
} else if (address.IsHeNet()) {
// for he.net, use /36 groups
nBits = 36;
} else {
// for the rest of the IPv6 network, use /32 groups
nBits = 32;
}
// Push our address onto vchRet.
auto addr_bytes = address.GetAddrBytes();
const size_t num_bytes = nBits / 8;
vchRet.insert(vchRet.end(), addr_bytes.begin() + nStartByte, addr_bytes.begin() + nStartByte + num_bytes);
nBits %= 8;
// ...for the last byte, push nBits and for the rest of the byte push 1's
if (nBits > 0) {
assert(num_bytes < addr_bytes.size());
vchRet.push_back(addr_bytes[num_bytes + nStartByte] | ((1 << (8 - nBits)) - 1));
}
return vchRet;
}
uint32_t NetGroupManager::GetMappedAS(const CNetAddr& address) const
{
uint32_t net_class = address.GetNetClass();
if (m_asmap.size() == 0 || (net_class != NET_IPV4 && net_class != NET_IPV6)) {
return 0; // Indicates not found, safe because AS0 is reserved per RFC7607.
}
std::vector<bool> ip_bits(128);
if (address.HasLinkedIPv4()) {
// For lookup, treat as if it was just an IPv4 address (IPV4_IN_IPV6_PREFIX + IPv4 bits)
for (int8_t byte_i = 0; byte_i < 12; ++byte_i) {
for (uint8_t bit_i = 0; bit_i < 8; ++bit_i) {
ip_bits[byte_i * 8 + bit_i] = (IPV4_IN_IPV6_PREFIX[byte_i] >> (7 - bit_i)) & 1;
}
}
uint32_t ipv4 = address.GetLinkedIPv4();
for (int i = 0; i < 32; ++i) {
ip_bits[96 + i] = (ipv4 >> (31 - i)) & 1;
}
} else {
// Use all 128 bits of the IPv6 address otherwise
assert(address.IsIPv6());
auto addr_bytes = address.GetAddrBytes();
for (int8_t byte_i = 0; byte_i < 16; ++byte_i) {
uint8_t cur_byte = addr_bytes[byte_i];
for (uint8_t bit_i = 0; bit_i < 8; ++bit_i) {
ip_bits[byte_i * 8 + bit_i] = (cur_byte >> (7 - bit_i)) & 1;
}
}
}
uint32_t mapped_as = Interpret(m_asmap, ip_bits);
return mapped_as;
}
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