* Get the canonical identifier of our network group * * The groups are assigned in a way where it should be costly for an attacker to * obtain addresses with many different group identifiers, even if it is cheap * to obtain addresses with the same identifier. * * @note No two connections will be attempted to addresses with the same network * group. */
| 764 | * group. |
| 765 | */ |
| 766 | std::vector<unsigned char> CNetAddr::GetGroup(const std::vector<bool> &asmap) const |
| 767 | { |
| 768 | std::vector<unsigned char> vchRet; |
| 769 | uint32_t net_class = GetNetClass(); |
| 770 | // If non-empty asmap is supplied and the address is IPv4/IPv6, |
| 771 | // return ASN to be used for bucketing. |
| 772 | uint32_t asn = GetMappedAS(asmap); |
| 773 | if (asn != 0) { // Either asmap was empty, or address has non-asmappable net class (e.g. TOR). |
| 774 | vchRet.push_back(NET_IPV6); // IPv4 and IPv6 with same ASN should be in the same bucket |
| 775 | for (int i = 0; i < 4; i++) { |
| 776 | vchRet.push_back((asn >> (8 * i)) & 0xFF); |
| 777 | } |
| 778 | return vchRet; |
| 779 | } |
| 780 | |
| 781 | vchRet.push_back(net_class); |
| 782 | int nBits{0}; |
| 783 | |
| 784 | if (IsLocal()) { |
| 785 | // all local addresses belong to the same group |
| 786 | } else if (IsInternal()) { |
| 787 | // all internal-usage addresses get their own group |
| 788 | nBits = ADDR_INTERNAL_SIZE * 8; |
| 789 | } else if (!IsRoutable()) { |
| 790 | // all other unroutable addresses belong to the same group |
| 791 | } else if (HasLinkedIPv4()) { |
| 792 | // IPv4 addresses (and mapped IPv4 addresses) use /16 groups |
| 793 | uint32_t ipv4 = GetLinkedIPv4(); |
| 794 | vchRet.push_back((ipv4 >> 24) & 0xFF); |
| 795 | vchRet.push_back((ipv4 >> 16) & 0xFF); |
| 796 | return vchRet; |
| 797 | } else if (IsTor() || IsI2P()) { |
| 798 | nBits = 4; |
| 799 | } else if (IsCJDNS()) { |
| 800 | // Treat in the same way as Tor and I2P because the address in all of |
| 801 | // them is "random" bytes (derived from a public key). However in CJDNS |
| 802 | // the first byte is a constant 0xfc, so the random bytes come after it. |
| 803 | // Thus skip the constant 8 bits at the start. |
| 804 | nBits = 12; |
| 805 | } else if (IsHeNet()) { |
| 806 | // for he.net, use /36 groups |
| 807 | nBits = 36; |
| 808 | } else { |
| 809 | // for the rest of the IPv6 network, use /32 groups |
| 810 | nBits = 32; |
| 811 | } |
| 812 | |
| 813 | // Push our address onto vchRet. |
| 814 | const size_t num_bytes = nBits / 8; |
| 815 | vchRet.insert(vchRet.end(), m_addr.begin(), m_addr.begin() + num_bytes); |
| 816 | nBits %= 8; |
| 817 | // ...for the last byte, push nBits and for the rest of the byte push 1's |
| 818 | if (nBits > 0) { |
| 819 | assert(num_bytes < m_addr.size()); |
| 820 | vchRet.push_back(m_addr[num_bytes] | ((1 << (8 - nBits)) - 1)); |
| 821 | } |
| 822 | |
| 823 | return vchRet; |