netaddress.cpp

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// Copyright (c) 2009-2010 Satoshi Nakamoto
// Copyright (c) 2009-2016 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 <netaddress.h>

#include <hash.h>
#include <tinyformat.h>
#include <util/asmap.h>
#include <util/strencodings.h>

static const uint8_t pchIPv4[12] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0xff, 0xff};
static const uint8_t pchOnionCat[] = {0xFD, 0x87, 0xD8, 0x7E, 0xEB, 0x43};

// 0xFD + sha256("bitcoin")[0:5]
static const uint8_t g_internal_prefix[] = {0xFD, 0x6B, 0x88, 0xC0, 0x87, 0x24};

CNetAddr::CNetAddr() {
    memset(ip, 0, sizeof(ip));
}

void CNetAddr::SetIP(const CNetAddr &ipIn) {
    memcpy(ip, ipIn.ip, sizeof(ip));
}

void CNetAddr::SetRaw(Network network, const uint8_t *ip_in) {
    switch (network) {
        case NET_IPV4:
            memcpy(ip, pchIPv4, 12);
            memcpy(ip + 12, ip_in, 4);
            break;
        case NET_IPV6:
            memcpy(ip, ip_in, 16);
            break;
        default:
            assert(!"invalid network");
    }
}

bool CNetAddr::SetInternal(const std::string &name) {
    if (name.empty()) {
        return false;
    }
    uint8_t hash[32] = {};
    CSHA256().Write((const uint8_t *)name.data(), name.size()).Finalize(hash);
    memcpy(ip, g_internal_prefix, sizeof(g_internal_prefix));
    memcpy(ip + sizeof(g_internal_prefix), hash,
           sizeof(ip) - sizeof(g_internal_prefix));
    return true;
}

bool CNetAddr::SetSpecial(const std::string &strName) {
    if (strName.size() > 6 &&
        strName.substr(strName.size() - 6, 6) == ".onion") {
        std::vector<uint8_t> vchAddr =
            DecodeBase32(strName.substr(0, strName.size() - 6).c_str());
        if (vchAddr.size() != 16 - sizeof(pchOnionCat)) {
            return false;
        }
        memcpy(ip, pchOnionCat, sizeof(pchOnionCat));
        for (unsigned int i = 0; i < 16 - sizeof(pchOnionCat); i++) {
            ip[i + sizeof(pchOnionCat)] = vchAddr[i];
        }
        return true;
    }
    return false;
}

CNetAddr::CNetAddr(const struct in_addr &ipv4Addr) {
    SetRaw(NET_IPV4, (const uint8_t *)&ipv4Addr);
}

CNetAddr::CNetAddr(const struct in6_addr &ipv6Addr, const uint32_t scope) {
    SetRaw(NET_IPV6, (const uint8_t *)&ipv6Addr);
    scopeId = scope;
}

unsigned int CNetAddr::GetByte(int n) const {
    return ip[15 - n];
}

bool CNetAddr::IsBindAny() const {
    const int cmplen = IsIPv4() ? 4 : 16;
    for (int i = 0; i < cmplen; ++i) {
        if (GetByte(i)) {
            return false;
        }
    }

    return true;
}

bool CNetAddr::IsIPv4() const {
    return (memcmp(ip, pchIPv4, sizeof(pchIPv4)) == 0);
}

bool CNetAddr::IsIPv6() const {
    return !IsIPv4() && !IsTor() && !IsInternal();
}

bool CNetAddr::IsRFC1918() const {
    return IsIPv4() &&
           (GetByte(3) == 10 || (GetByte(3) == 192 && GetByte(2) == 168) ||
            (GetByte(3) == 172 && (GetByte(2) >= 16 && GetByte(2) <= 31)));
}

bool CNetAddr::IsRFC2544() const {
    return IsIPv4() && GetByte(3) == 198 &&
           (GetByte(2) == 18 || GetByte(2) == 19);
}

bool CNetAddr::IsRFC3927() const {
    return IsIPv4() && (GetByte(3) == 169 && GetByte(2) == 254);
}

bool CNetAddr::IsRFC6598() const {
    return IsIPv4() && GetByte(3) == 100 && GetByte(2) >= 64 &&
           GetByte(2) <= 127;
}

bool CNetAddr::IsRFC5737() const {
    return IsIPv4() &&
           ((GetByte(3) == 192 && GetByte(2) == 0 && GetByte(1) == 2) ||
            (GetByte(3) == 198 && GetByte(2) == 51 && GetByte(1) == 100) ||
            (GetByte(3) == 203 && GetByte(2) == 0 && GetByte(1) == 113));
}

bool CNetAddr::IsRFC3849() const {
    return GetByte(15) == 0x20 && GetByte(14) == 0x01 && GetByte(13) == 0x0D &&
           GetByte(12) == 0xB8;
}

bool CNetAddr::IsRFC3964() const {
    return (GetByte(15) == 0x20 && GetByte(14) == 0x02);
}

bool CNetAddr::IsRFC6052() const {
    static const uint8_t pchRFC6052[] = {0, 0x64, 0xFF, 0x9B, 0, 0,
                                         0, 0,    0,    0,    0, 0};
    return (memcmp(ip, pchRFC6052, sizeof(pchRFC6052)) == 0);
}

bool CNetAddr::IsRFC4380() const {
    return (GetByte(15) == 0x20 && GetByte(14) == 0x01 && GetByte(13) == 0 &&
            GetByte(12) == 0);
}

bool CNetAddr::IsRFC4862() const {
    static const uint8_t pchRFC4862[] = {0xFE, 0x80, 0, 0, 0, 0, 0, 0};
    return (memcmp(ip, pchRFC4862, sizeof(pchRFC4862)) == 0);
}

bool CNetAddr::IsRFC4193() const {
    return ((GetByte(15) & 0xFE) == 0xFC);
}

bool CNetAddr::IsRFC6145() const {
    static const uint8_t pchRFC6145[] = {0, 0, 0,    0,    0, 0,
                                         0, 0, 0xFF, 0xFF, 0, 0};
    return (memcmp(ip, pchRFC6145, sizeof(pchRFC6145)) == 0);
}

bool CNetAddr::IsRFC4843() const {
    return (GetByte(15) == 0x20 && GetByte(14) == 0x01 && GetByte(13) == 0x00 &&
            (GetByte(12) & 0xF0) == 0x10);
}

bool CNetAddr::IsRFC7343() const {
    return (GetByte(15) == 0x20 && GetByte(14) == 0x01 && GetByte(13) == 0x00 &&
            (GetByte(12) & 0xF0) == 0x20);
}

bool CNetAddr::IsHeNet() const {
    return (GetByte(15) == 0x20 && GetByte(14) == 0x01 && GetByte(13) == 0x04 &&
            GetByte(12) == 0x70);
}

bool CNetAddr::IsTor() const {
    return (memcmp(ip, pchOnionCat, sizeof(pchOnionCat)) == 0);
}

bool CNetAddr::IsLocal() const {
    // IPv4 loopback (127.0.0.0/8 or 0.0.0.0/8)
    if (IsIPv4() && (GetByte(3) == 127 || GetByte(3) == 0)) {
        return true;
    }

    // IPv6 loopback (::1/128)
    static const uint8_t pchLocal[16] = {0, 0, 0, 0, 0, 0, 0, 0,
                                         0, 0, 0, 0, 0, 0, 0, 1};
    if (memcmp(ip, pchLocal, 16) == 0) {
        return true;
    }

    return false;
}

bool CNetAddr::IsValid() const {
    // Cleanup 3-byte shifted addresses caused by garbage in size field of addr
    // messages from versions before 0.2.9 checksum.
    // Two consecutive addr messages look like this:
    // header20 vectorlen3 addr26 addr26 addr26 header20 vectorlen3 addr26
    // addr26 addr26... so if the first length field is garbled, it reads the
    // second batch of addr misaligned by 3 bytes.
    if (memcmp(ip, pchIPv4 + 3, sizeof(pchIPv4) - 3) == 0) {
        return false;
    }

    // unspecified IPv6 address (::/128)
    uint8_t ipNone6[16] = {};
    if (memcmp(ip, ipNone6, 16) == 0) {
        return false;
    }

    // documentation IPv6 address
    if (IsRFC3849()) {
        return false;
    }

    if (IsInternal()) {
        return false;
    }

    if (IsIPv4()) {
        // INADDR_NONE
        uint32_t ipNone = INADDR_NONE;
        if (memcmp(ip + 12, &ipNone, 4) == 0) {
            return false;
        }

        // 0
        ipNone = 0;
        if (memcmp(ip + 12, &ipNone, 4) == 0) {
            return false;
        }
    }

    return true;
}

bool CNetAddr::IsRoutable() const {
    return IsValid() &&
           !(IsRFC1918() || IsRFC2544() || IsRFC3927() || IsRFC4862() ||
             IsRFC6598() || IsRFC5737() || (IsRFC4193() && !IsTor()) ||
             IsRFC4843() || IsRFC7343() || IsLocal() || IsInternal());
}

bool CNetAddr::IsInternal() const {
    return memcmp(ip, g_internal_prefix, sizeof(g_internal_prefix)) == 0;
}

enum Network CNetAddr::GetNetwork() const {
    if (IsInternal()) {
        return NET_INTERNAL;
    }

    if (!IsRoutable()) {
        return NET_UNROUTABLE;
    }

    if (IsIPv4()) {
        return NET_IPV4;
    }

    if (IsTor()) {
        return NET_ONION;
    }

    return NET_IPV6;
}

std::string CNetAddr::ToStringIP() const {
    if (IsTor()) {
        return EncodeBase32(&ip[6], 10) + ".onion";
    }
    if (IsInternal()) {
        return EncodeBase32(ip + sizeof(g_internal_prefix),
                            sizeof(ip) - sizeof(g_internal_prefix)) +
               ".internal";
    }
    CService serv(*this, 0);
    struct sockaddr_storage sockaddr;
    socklen_t socklen = sizeof(sockaddr);
    if (serv.GetSockAddr((struct sockaddr *)&sockaddr, &socklen)) {
        char name[1025] = "";
        if (!getnameinfo((const struct sockaddr *)&sockaddr, socklen, name,
                         sizeof(name), nullptr, 0, NI_NUMERICHOST)) {
            return std::string(name);
        }
    }
    if (IsIPv4()) {
        return strprintf("%u.%u.%u.%u", GetByte(3), GetByte(2), GetByte(1),
                         GetByte(0));
    }

    return strprintf("%x:%x:%x:%x:%x:%x:%x:%x", GetByte(15) << 8 | GetByte(14),
                     GetByte(13) << 8 | GetByte(12),
                     GetByte(11) << 8 | GetByte(10),
                     GetByte(9) << 8 | GetByte(8), GetByte(7) << 8 | GetByte(6),
                     GetByte(5) << 8 | GetByte(4), GetByte(3) << 8 | GetByte(2),
                     GetByte(1) << 8 | GetByte(0));
}

std::string CNetAddr::ToString() const {
    return ToStringIP();
}

bool operator==(const CNetAddr &a, const CNetAddr &b) {
    return (memcmp(a.ip, b.ip, 16) == 0);
}

bool operator<(const CNetAddr &a, const CNetAddr &b) {
    return (memcmp(a.ip, b.ip, 16) < 0);
}

bool CNetAddr::GetInAddr(struct in_addr *pipv4Addr) const {
    if (!IsIPv4()) {
        return false;
    }
    memcpy(pipv4Addr, ip + 12, 4);
    return true;
}

bool CNetAddr::GetIn6Addr(struct in6_addr *pipv6Addr) const {
    if (!IsIPv6()) {
        return false;
    }
    memcpy(pipv6Addr, ip, 16);
    return true;
}

bool CNetAddr::HasLinkedIPv4() const {
    return IsRoutable() && (IsIPv4() || IsRFC6145() || IsRFC6052() ||
                            IsRFC3964() || IsRFC4380());
}

uint32_t CNetAddr::GetLinkedIPv4() const {
    if (IsIPv4() || IsRFC6145() || IsRFC6052()) {
        // IPv4, mapped IPv4, SIIT translated IPv4: the IPv4 address is the last
        // 4 bytes of the address
        return ReadBE32(ip + 12);
    } else if (IsRFC3964()) {
        // 6to4 tunneled IPv4: the IPv4 address is in bytes 2-6
        return ReadBE32(ip + 2);
    } else if (IsRFC4380()) {
        // Teredo tunneled IPv4: the IPv4 address is in the last 4 bytes of the
        // address, but bitflipped
        return ~ReadBE32(ip + 12);
    }
    assert(false);
}

uint32_t CNetAddr::GetNetClass() const {
    uint32_t net_class = NET_IPV6;
    if (IsLocal()) {
        net_class = 255;
    }
    if (IsInternal()) {
        net_class = NET_INTERNAL;
    } else if (!IsRoutable()) {
        net_class = NET_UNROUTABLE;
    } else if (HasLinkedIPv4()) {
        net_class = NET_IPV4;
    } else if (IsTor()) {
        net_class = NET_ONION;
    }
    return net_class;
}

uint32_t CNetAddr::GetMappedAS(const std::vector<bool> &asmap) const {
    uint32_t net_class = GetNetClass();
    if (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 (HasLinkedIPv4()) {
        // For lookup, treat as if it was just an IPv4 address (pchIPv4 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] =
                    (pchIPv4[byte_i] >> (7 - bit_i)) & 1;
            }
        }
        uint32_t ipv4 = 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
        for (int8_t byte_i = 0; byte_i < 16; ++byte_i) {
            uint8_t cur_byte = GetByte(15 - 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(asmap, ip_bits);
    return mapped_as;
}

std::vector<uint8_t> CNetAddr::GetGroup(const std::vector<bool> &asmap) const {
    std::vector<uint8_t> vchRet;
    uint32_t net_class = GetNetClass();
    // If non-empty asmap is supplied and the address is IPv4/IPv6,
    // return ASN to be used for bucketing.
    uint32_t asn = GetMappedAS(asmap);
    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(net_class);
    int nStartByte = 0;
    int nBits = 16;

    if (IsLocal()) {
        // all local addresses belong to the same group
        nBits = 0;
    } else if (IsInternal()) {
        // all internal-usage addresses get their own group
        nStartByte = sizeof(g_internal_prefix);
        nBits = (sizeof(ip) - sizeof(g_internal_prefix)) * 8;
    } else if (!IsRoutable()) {
        // all other unroutable addresses belong to the same group
        nBits = 0;
    } else if (HasLinkedIPv4()) {
        // IPv4 addresses (and mapped IPv4 addresses) use /16 groups
        uint32_t ipv4 = GetLinkedIPv4();
        vchRet.push_back((ipv4 >> 24) & 0xFF);
        vchRet.push_back((ipv4 >> 16) & 0xFF);
        return vchRet;
    } else if (IsTor()) {
        nStartByte = 6;
        nBits = 4;
    } else if (IsHeNet()) {
        // for he.net, use /36 groups
        nBits = 36;
    } else {
        // for the rest of the IPv6 network, use /32 groups
        nBits = 32;
    }

    // push our ip onto vchRet byte by byte...
    while (nBits >= 8) {
        vchRet.push_back(GetByte(15 - nStartByte));
        nStartByte++;
        nBits -= 8;
    }
    // ...for the last byte, push nBits and for the rest of the byte push 1's
    if (nBits > 0) {
        vchRet.push_back(GetByte(15 - nStartByte) | ((1 << (8 - nBits)) - 1));
    }

    return vchRet;
}

uint64_t CNetAddr::GetHash() const {
    uint256 hash = Hash(&ip[0], &ip[16]);
    uint64_t nRet;
    memcpy(&nRet, &hash, sizeof(nRet));
    return nRet;
}

// private extensions to enum Network, only returned by GetExtNetwork, and only
// used in GetReachabilityFrom
static const int NET_UNKNOWN = NET_MAX + 0;
static const int NET_TEREDO = NET_MAX + 1;
static int GetExtNetwork(const CNetAddr *addr) {
    if (addr == nullptr) {
        return NET_UNKNOWN;
    }
    if (addr->IsRFC4380()) {
        return NET_TEREDO;
    }
    return addr->GetNetwork();
}

int CNetAddr::GetReachabilityFrom(const CNetAddr *paddrPartner) const {
    enum Reachability {
        REACH_UNREACHABLE,
        REACH_DEFAULT,
        REACH_TEREDO,
        REACH_IPV6_WEAK,
        REACH_IPV4,
        REACH_IPV6_STRONG,
        REACH_PRIVATE
    };

    if (!IsRoutable() || IsInternal()) {
        return REACH_UNREACHABLE;
    }

    int ourNet = GetExtNetwork(this);
    int theirNet = GetExtNetwork(paddrPartner);
    bool fTunnel = IsRFC3964() || IsRFC6052() || IsRFC6145();

    switch (theirNet) {
        case NET_IPV4:
            switch (ourNet) {
                default:
                    return REACH_DEFAULT;
                case NET_IPV4:
                    return REACH_IPV4;
            }
        case NET_IPV6:
            switch (ourNet) {
                default:
                    return REACH_DEFAULT;
                case NET_TEREDO:
                    return REACH_TEREDO;
                case NET_IPV4:
                    return REACH_IPV4;
                // only prefer giving our IPv6 address if it's not tunnelled
                case NET_IPV6:
                    return fTunnel ? REACH_IPV6_WEAK : REACH_IPV6_STRONG;
            }
        case NET_ONION:
            switch (ourNet) {
                default:
                    return REACH_DEFAULT;
                // Tor users can connect to IPv4 as well
                case NET_IPV4:
                    return REACH_IPV4;
                case NET_ONION:
                    return REACH_PRIVATE;
            }
        case NET_TEREDO:
            switch (ourNet) {
                default:
                    return REACH_DEFAULT;
                case NET_TEREDO:
                    return REACH_TEREDO;
                case NET_IPV6:
                    return REACH_IPV6_WEAK;
                case NET_IPV4:
                    return REACH_IPV4;
            }
        case NET_UNKNOWN:
        case NET_UNROUTABLE:
        default:
            switch (ourNet) {
                default:
                    return REACH_DEFAULT;
                case NET_TEREDO:
                    return REACH_TEREDO;
                case NET_IPV6:
                    return REACH_IPV6_WEAK;
                case NET_IPV4:
                    return REACH_IPV4;
                // either from Tor, or don't care about our address
                case NET_ONION:
                    return REACH_PRIVATE;
            }
    }
}

CService::CService() : port(0) {}

CService::CService(const CNetAddr &cip, unsigned short portIn)
    : CNetAddr(cip), port(portIn) {}

CService::CService(const struct in_addr &ipv4Addr, unsigned short portIn)
    : CNetAddr(ipv4Addr), port(portIn) {}

CService::CService(const struct in6_addr &ipv6Addr, unsigned short portIn)
    : CNetAddr(ipv6Addr), port(portIn) {}

CService::CService(const struct sockaddr_in &addr)
    : CNetAddr(addr.sin_addr), port(ntohs(addr.sin_port)) {
    assert(addr.sin_family == AF_INET);
}

CService::CService(const struct sockaddr_in6 &addr)
    : CNetAddr(addr.sin6_addr, addr.sin6_scope_id),
      port(ntohs(addr.sin6_port)) {
    assert(addr.sin6_family == AF_INET6);
}

bool CService::SetSockAddr(const struct sockaddr *paddr) {
    switch (paddr->sa_family) {
        case AF_INET:
            *this =
                CService(*reinterpret_cast<const struct sockaddr_in *>(paddr));
            return true;
        case AF_INET6:
            *this =
                CService(*reinterpret_cast<const struct sockaddr_in6 *>(paddr));
            return true;
        default:
            return false;
    }
}

unsigned short CService::GetPort() const {
    return port;
}

bool operator==(const CService &a, const CService &b) {
    return static_cast<CNetAddr>(a) == static_cast<CNetAddr>(b) &&
           a.port == b.port;
}

bool operator<(const CService &a, const CService &b) {
    return static_cast<CNetAddr>(a) < static_cast<CNetAddr>(b) ||
           (static_cast<CNetAddr>(a) == static_cast<CNetAddr>(b) &&
            a.port < b.port);
}

bool CService::GetSockAddr(struct sockaddr *paddr, socklen_t *addrlen) const {
    if (IsIPv4()) {
        if (*addrlen < (socklen_t)sizeof(struct sockaddr_in)) {
            return false;
        }
        *addrlen = sizeof(struct sockaddr_in);
        struct sockaddr_in *paddrin =
            reinterpret_cast<struct sockaddr_in *>(paddr);
        memset(paddrin, 0, *addrlen);
        if (!GetInAddr(&paddrin->sin_addr)) {
            return false;
        }
        paddrin->sin_family = AF_INET;
        paddrin->sin_port = htons(port);
        return true;
    }
    if (IsIPv6()) {
        if (*addrlen < (socklen_t)sizeof(struct sockaddr_in6)) {
            return false;
        }
        *addrlen = sizeof(struct sockaddr_in6);
        struct sockaddr_in6 *paddrin6 =
            reinterpret_cast<struct sockaddr_in6 *>(paddr);
        memset(paddrin6, 0, *addrlen);
        if (!GetIn6Addr(&paddrin6->sin6_addr)) {
            return false;
        }
        paddrin6->sin6_scope_id = scopeId;
        paddrin6->sin6_family = AF_INET6;
        paddrin6->sin6_port = htons(port);
        return true;
    }
    return false;
}

std::vector<uint8_t> CService::GetKey() const {
    std::vector<uint8_t> vKey;
    vKey.resize(18);
    memcpy(vKey.data(), ip, 16);
    // most significant byte of our port
    vKey[16] = port / 0x100;
    // least significant byte of our port
    vKey[17] = port & 0x0FF;
    return vKey;
}

std::string CService::ToStringPort() const {
    return strprintf("%u", port);
}

std::string CService::ToStringIPPort() const {
    if (IsIPv4() || IsTor() || IsInternal()) {
        return ToStringIP() + ":" + ToStringPort();
    } else {
        return "[" + ToStringIP() + "]:" + ToStringPort();
    }
}

std::string CService::ToString() const {
    return ToStringIPPort();
}

CSubNet::CSubNet() : valid(false) {
    memset(netmask, 0, sizeof(netmask));
}

CSubNet::CSubNet(const CNetAddr &addr, int32_t mask) {
    valid = true;
    network = addr;
    // Default to /32 (IPv4) or /128 (IPv6), i.e. match single address
    memset(netmask, 255, sizeof(netmask));

    // IPv4 addresses start at offset 12, and first 12 bytes must match, so just
    // offset n
    const int astartofs = network.IsIPv4() ? 12 : 0;

    // Only valid if in range of bits of address
    int32_t n = mask;
    if (n >= 0 && n <= (128 - astartofs * 8)) {
        n += astartofs * 8;
        // Clear bits [n..127]
        for (; n < 128; ++n) {
            netmask[n >> 3] &= ~(1 << (7 - (n & 7)));
        }
    } else {
        valid = false;
    }

    // Normalize network according to netmask
    for (int x = 0; x < 16; ++x) {
        network.ip[x] &= netmask[x];
    }
}

CSubNet::CSubNet(const CNetAddr &addr, const CNetAddr &mask) {
    valid = true;
    network = addr;
    // Default to /32 (IPv4) or /128 (IPv6), i.e. match single address
    memset(netmask, 255, sizeof(netmask));

    // IPv4 addresses start at offset 12, and first 12 bytes must match, so just
    // offset n
    const int astartofs = network.IsIPv4() ? 12 : 0;

    for (int x = astartofs; x < 16; ++x) {
        netmask[x] = mask.ip[x];
    }

    // Normalize network according to netmask
    for (int x = 0; x < 16; ++x) {
        network.ip[x] &= netmask[x];
    }
}

CSubNet::CSubNet(const CNetAddr &addr) : valid(addr.IsValid()) {
    memset(netmask, 255, sizeof(netmask));
    network = addr;
}

bool CSubNet::Match(const CNetAddr &addr) const {
    if (!valid || !addr.IsValid()) {
        return false;
    }
    for (int x = 0; x < 16; ++x) {
        if ((addr.ip[x] & netmask[x]) != network.ip[x]) {
            return false;
        }
    }
    return true;
}

static inline int NetmaskBits(uint8_t x) {
    switch (x) {
        case 0x00:
            return 0;
        case 0x80:
            return 1;
        case 0xc0:
            return 2;
        case 0xe0:
            return 3;
        case 0xf0:
            return 4;
        case 0xf8:
            return 5;
        case 0xfc:
            return 6;
        case 0xfe:
            return 7;
        case 0xff:
            return 8;
        default:
            return -1;
    }
}

std::string CSubNet::ToString() const {
    /* Parse binary 1{n}0{N-n} to see if mask can be represented as /n */
    int cidr = 0;
    bool valid_cidr = true;
    int n = network.IsIPv4() ? 12 : 0;
    for (; n < 16 && netmask[n] == 0xff; ++n) {
        cidr += 8;
    }
    if (n < 16) {
        int bits = NetmaskBits(netmask[n]);
        if (bits < 0) {
            valid_cidr = false;
        } else {
            cidr += bits;
        }
        ++n;
    }
    for (; n < 16 && valid_cidr; ++n) {
        if (netmask[n] != 0x00) {
            valid_cidr = false;
        }
    }

    /* Format output */
    std::string strNetmask;
    if (valid_cidr) {
        strNetmask = strprintf("%u", cidr);
    } else {
        if (network.IsIPv4()) {
            strNetmask = strprintf("%u.%u.%u.%u", netmask[12], netmask[13],
                                   netmask[14], netmask[15]);
        } else {
            strNetmask = strprintf(
                "%x:%x:%x:%x:%x:%x:%x:%x", netmask[0] << 8 | netmask[1],
                netmask[2] << 8 | netmask[3], netmask[4] << 8 | netmask[5],
                netmask[6] << 8 | netmask[7], netmask[8] << 8 | netmask[9],
                netmask[10] << 8 | netmask[11], netmask[12] << 8 | netmask[13],
                netmask[14] << 8 | netmask[15]);
        }
    }

    return network.ToString() + "/" + strNetmask;
}

bool CSubNet::IsValid() const {
    return valid;
}

bool operator==(const CSubNet &a, const CSubNet &b) {
    return a.valid == b.valid && a.network == b.network &&
           !memcmp(a.netmask, b.netmask, 16);
}

bool operator<(const CSubNet &a, const CSubNet &b) {
    return (a.network < b.network ||
            (a.network == b.network && memcmp(a.netmask, b.netmask, 16) < 0));
}

bool SanityCheckASMap(const std::vector<bool> &asmap) {
    // For IP address lookups, the input is 128 bits
    return SanityCheckASMap(asmap, 128);
}