text: // Copyright (c) 2009-2010 Satoshi Nakamoto
  // Copyright (c) 2009-2020 The aRIA 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 <crypto/common.h>
  #include <crypto/sha3.h>
  #include <hash.h>
  #include <prevector.h>
  #include <tinyformat.h>
  #include <util/asmap.h>
  #include <util/strencodings.h>
  #include <util/string.h>
  
  #include <algorithm>
  #include <array>
  #include <cstdint>
  #include <ios>
  #include <iterator>
  #include <tuple>
  
  constexpr size_t CNetAddr::V1_SERIALIZATION_SIZE;
  constexpr size_t CNetAddr::MAX_ADDRV2_SIZE;
  
  CNetAddr::BIP155Network CNetAddr::GetBIP155Network() const
  {
      switch (m_net) {
      case NET_IPV4:
          return BIP155Network::IPV4;
      case NET_IPV6:
          return BIP155Network::IPV6;
      case NET_ONION:
          switch (m_addr.size()) {
          case ADDR_TORV2_SIZE:
              return BIP155Network::TORV2;
          case ADDR_TORV3_SIZE:
              return BIP155Network::TORV3;
          default:
              assert(false);
          }
      case NET_I2P:
          return BIP155Network::I2P;
      case NET_CJDNS:
          return BIP155Network::CJDNS;
      case NET_INTERNAL:   // should have been handled before calling this function
      case NET_UNROUTABLE: // m_net is never and should not be set to NET_UNROUTABLE
      case NET_MAX:        // m_net is never and should not be set to NET_MAX
          assert(false);
      } // no default case, so the compiler can warn about missing cases
  
      assert(false);
  }
  
  bool CNetAddr::SetNetFromBIP155Network(uint8_t possible_bip155_net, size_t address_size)
  {
      switch (possible_bip155_net) {
      case BIP155Network::IPV4:
          if (address_size == ADDR_IPV4_SIZE) {
              m_net = NET_IPV4;
              return true;
          }
          throw std::ios_base::failure(
              strprintf("BIP155 IPv4 address with length %u (should be %u)", address_size,
                        ADDR_IPV4_SIZE));
      case BIP155Network::IPV6:
          if (address_size == ADDR_IPV6_SIZE) {
              m_net = NET_IPV6;
              return true;
          }
          throw std::ios_base::failure(
              strprintf("BIP155 IPv6 address with length %u (should be %u)", address_size,
                        ADDR_IPV6_SIZE));
      case BIP155Network::TORV2:
          if (address_size == ADDR_TORV2_SIZE) {
              m_net = NET_ONION;
              return true;
          }
          throw std::ios_base::failure(
              strprintf("BIP155 TORv2 address with length %u (should be %u)", address_size,
                        ADDR_TORV2_SIZE));
      case BIP155Network::TORV3:
          if (address_size == ADDR_TORV3_SIZE) {
              m_net = NET_ONION;
              return true;
          }
          throw std::ios_base::failure(
              strprintf("BIP155 TORv3 address with length %u (should be %u)", address_size,
                        ADDR_TORV3_SIZE));
      case BIP155Network::I2P:
          if (address_size == ADDR_I2P_SIZE) {
              m_net = NET_I2P;
              return true;
          }
          throw std::ios_base::failure(
              strprintf("BIP155 I2P address with length %u (should be %u)", address_size,
                        ADDR_I2P_SIZE));
      case BIP155Network::CJDNS:
          if (address_size == ADDR_CJDNS_SIZE) {
              m_net = NET_CJDNS;
              return true;
          }
          throw std::ios_base::failure(
              strprintf("BIP155 CJDNS address with length %u (should be %u)", address_size,
                        ADDR_CJDNS_SIZE));
      }
  
      // Don't throw on addresses with unknown network ids (maybe from the future).
      // Instead silently drop them and have the unserialization code consume
      // subsequent ones which may be known to us.
      return false;
  }
  
  /**
   * Construct an unspecified IPv6 network address (::/128).
   *
   * @note This address is considered invalid by CNetAddr::IsValid()
   */
  CNetAddr::CNetAddr() {}
  
  void CNetAddr::SetIP(const CNetAddr& ipIn)
  {
      // Size check.
      switch (ipIn.m_net) {
      case NET_IPV4:
          assert(ipIn.m_addr.size() == ADDR_IPV4_SIZE);
          break;
      case NET_IPV6:
          assert(ipIn.m_addr.size() == ADDR_IPV6_SIZE);
          break;
      case NET_ONION:
          assert(ipIn.m_addr.size() == ADDR_TORV2_SIZE || ipIn.m_addr.size() == ADDR_TORV3_SIZE);
          break;
      case NET_I2P:
          assert(ipIn.m_addr.size() == ADDR_I2P_SIZE);
          break;
      case NET_CJDNS:
          assert(ipIn.m_addr.size() == ADDR_CJDNS_SIZE);
          break;
      case NET_INTERNAL:
          assert(ipIn.m_addr.size() == ADDR_INTERNAL_SIZE);
          break;
      case NET_UNROUTABLE:
      case NET_MAX:
          assert(false);
      } // no default case, so the compiler can warn about missing cases
  
      m_net = ipIn.m_net;
      m_addr = ipIn.m_addr;
  }
  
  void CNetAddr::SetLegacyIPv6(Span<const uint8_t> ipv6)
  {
      assert(ipv6.size() == ADDR_IPV6_SIZE);
  
      size_t skip{0};
  
      if (HasPrefix(ipv6, IPV4_IN_IPV6_PREFIX)) {
          // IPv4-in-IPv6
          m_net = NET_IPV4;
          skip = sizeof(IPV4_IN_IPV6_PREFIX);
      } else if (HasPrefix(ipv6, TORV2_IN_IPV6_PREFIX)) {
          // TORv2-in-IPv6
          m_net = NET_ONION;
          skip = sizeof(TORV2_IN_IPV6_PREFIX);
      } else if (HasPrefix(ipv6, INTERNAL_IN_IPV6_PREFIX)) {
          // Internal-in-IPv6
          m_net = NET_INTERNAL;
          skip = sizeof(INTERNAL_IN_IPV6_PREFIX);
      } else {
          // IPv6
          m_net = NET_IPV6;
      }
  
      m_addr.assign(ipv6.begin() + skip, ipv6.end());
  }
  
  /**
   * Create an "internal" address that represents a name or FQDN. CAddrMan uses
   * these fake addresses to keep track of which DNS seeds were used.
   * @returns Whether or not the operation was successful.
   * @see NET_INTERNAL, INTERNAL_IN_IPV6_PREFIX, CNetAddr::IsInternal(), CNetAddr::IsRFC4193()
   */
  bool CNetAddr::SetInternal(const std::string &name)
  {
      if (name.empty()) {
          return false;
      }
      m_net = NET_INTERNAL;
      unsigned char hash[32] = {};
      CSHA256().Write((const unsigned char*)name.data(), name.size()).Finalize(hash);
      m_addr.assign(hash, hash + ADDR_INTERNAL_SIZE);
      return true;
  }
  
  namespace torv3 {
  // https://gitweb.torproject.org/torspec.git/tree/rend-spec-v3.txt#n2135
  static constexpr size_t CHECKSUM_LEN = 2;
  static const unsigned char VERSION[] = {3};
  static constexpr size_t TOTAL_LEN = ADDR_TORV3_SIZE + CHECKSUM_LEN + sizeof(VERSION);
  
  static void Checksum(Span<const uint8_t> addr_pubkey, uint8_t (&checksum)[CHECKSUM_LEN])
  {
      // TORv3 CHECKSUM = H(".onion checksum" | PUBKEY | VERSION)[:2]
      static const unsigned char prefix[] = ".onion checksum";
      static constexpr size_t prefix_len = 15;
  
      SHA3_256 hasher;
  
      hasher.Write(MakeSpan(prefix).first(prefix_len));
      hasher.Write(addr_pubkey);
      hasher.Write(VERSION);
  
      uint8_t checksum_full[SHA3_256::OUTPUT_SIZE];
  
      hasher.Finalize(checksum_full);
  
      memcpy(checksum, checksum_full, sizeof(checksum));
  }
  
  }; // namespace torv3
  
  /**
   * Parse a TOR address and set this object to it.
   *
   * @returns Whether or not the operation was successful.
   *
   * @see CNetAddr::IsTor()
   */
  bool CNetAddr::SetSpecial(const std::string& str)
  {
      static const char* suffix{".onion"};
      static constexpr size_t suffix_len{6};
  
      if (!ValidAsCString(str) || str.size() <= suffix_len ||
          str.substr(str.size() - suffix_len) != suffix) {
          return false;
      }
  
      bool invalid;
      const auto& input = DecodeBase32(str.substr(0, str.size() - suffix_len).c_str(), &invalid);
  
      if (invalid) {
          return false;
      }
  
      switch (input.size()) {
      case ADDR_TORV2_SIZE:
          m_net = NET_ONION;
          m_addr.assign(input.begin(), input.end());
          return true;
      case torv3::TOTAL_LEN: {
          Span<const uint8_t> input_pubkey{input.data(), ADDR_TORV3_SIZE};
          Span<const uint8_t> input_checksum{input.data() + ADDR_TORV3_SIZE, torv3::CHECKSUM_LEN};
          Span<const uint8_t> input_version{input.data() + ADDR_TORV3_SIZE + torv3::CHECKSUM_LEN, sizeof(torv3::VERSION)};
  
          if (input_version != torv3::VERSION) {
              return false;
          }
  
          uint8_t calculated_checksum[torv3::CHECKSUM_LEN];
          torv3::Checksum(input_pubkey, calculated_checksum);
  
          if (input_checksum != calculated_checksum) {
              return false;
          }
  
          m_net = NET_ONION;
          m_addr.assign(input_pubkey.begin(), input_pubkey.end());
          return true;
      }
      }
  
      return false;
  }
  
  CNetAddr::CNetAddr(const struct in_addr& ipv4Addr)
  {
      m_net = NET_IPV4;
      const uint8_t* ptr = reinterpret_cast<const uint8_t*>(&ipv4Addr);
      m_addr.assign(ptr, ptr + ADDR_IPV4_SIZE);
  }
  
  CNetAddr::CNetAddr(const struct in6_addr& ipv6Addr, const uint32_t scope)
  {
      SetLegacyIPv6(Span<const uint8_t>(reinterpret_cast<const uint8_t*>(&ipv6Addr), sizeof(ipv6Addr)));
      m_scope_id = scope;
  }
  
  bool CNetAddr::IsBindAny() const
  {
      if (!IsIPv4() && !IsIPv6()) {
          return false;
      }
      return std::all_of(m_addr.begin(), m_addr.end(), [](uint8_t b) { return b == 0; });
  }
  
  bool CNetAddr::IsIPv4() const { return m_net == NET_IPV4; }
  
  bool CNetAddr::IsIPv6() const { return m_net == NET_IPV6; }
  
  bool CNetAddr::IsRFC1918() const
  {
      return IsIPv4() && (
          m_addr[0] == 10 ||
          (m_addr[0] == 192 && m_addr[1] == 168) ||
          (m_addr[0] == 172 && m_addr[1] >= 16 && m_addr[1] <= 31));
  }
  
  bool CNetAddr::IsRFC2544() const
  {
      return IsIPv4() && m_addr[0] == 198 && (m_addr[1] == 18 || m_addr[1] == 19);
  }
  
  bool CNetAddr::IsRFC3927() const
  {
      return IsIPv4() && HasPrefix(m_addr, std::array<uint8_t, 2>{169, 254});
  }
  
  bool CNetAddr::IsRFC6598() const
  {
      return IsIPv4() && m_addr[0] == 100 && m_addr[1] >= 64 && m_addr[1] <= 127;
  }
  
  bool CNetAddr::IsRFC5737() const
  {
      return IsIPv4() && (HasPrefix(m_addr, std::array<uint8_t, 3>{192, 0, 2}) ||
                          HasPrefix(m_addr, std::array<uint8_t, 3>{198, 51, 100}) ||
                          HasPrefix(m_addr, std::array<uint8_t, 3>{203, 0, 113}));
  }
  
  bool CNetAddr::IsRFC3849() const
  {
      return IsIPv6() && HasPrefix(m_addr, std::array<uint8_t, 4>{0x20, 0x01, 0x0D, 0xB8});
  }
  
  bool CNetAddr::IsRFC3964() const
  {
      return IsIPv6() && HasPrefix(m_addr, std::array<uint8_t, 2>{0x20, 0x02});
  }
  
  bool CNetAddr::IsRFC6052() const
  {
      return IsIPv6() &&
             HasPrefix(m_addr, std::array<uint8_t, 12>{0x00, 0x64, 0xFF, 0x9B, 0x00, 0x00,
                                                       0x00, 0x00, 0x00, 0x00, 0x00, 0x00});
  }
  
  bool CNetAddr::IsRFC4380() const
  {
      return IsIPv6() && HasPrefix(m_addr, std::array<uint8_t, 4>{0x20, 0x01, 0x00, 0x00});
  }
  
  bool CNetAddr::IsRFC4862() const
  {
      return IsIPv6() && HasPrefix(m_addr, std::array<uint8_t, 8>{0xFE, 0x80, 0x00, 0x00,
                                                                  0x00, 0x00, 0x00, 0x00});
  }
  
  bool CNetAddr::IsRFC4193() const
  {
      return IsIPv6() && (m_addr[0] & 0xFE) == 0xFC;
  }
  
  bool CNetAddr::IsRFC6145() const
  {
      return IsIPv6() &&
             HasPrefix(m_addr, std::array<uint8_t, 12>{0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
                                                       0x00, 0x00, 0xFF, 0xFF, 0x00, 0x00});
  }
  
  bool CNetAddr::IsRFC4843() const
  {
      return IsIPv6() && HasPrefix(m_addr, std::array<uint8_t, 3>{0x20, 0x01, 0x00}) &&
             (m_addr[3] & 0xF0) == 0x10;
  }
  
  bool CNetAddr::IsRFC7343() const
  {
      return IsIPv6() && HasPrefix(m_addr, std::array<uint8_t, 3>{0x20, 0x01, 0x00}) &&
             (m_addr[3] & 0xF0) == 0x20;
  }
  
  bool CNetAddr::IsHeNet() const
  {
      return IsIPv6() && HasPrefix(m_addr, std::array<uint8_t, 4>{0x20, 0x01, 0x04, 0x70});
  }
  
  /**
   * Check whether this object represents a TOR address.
   * @see CNetAddr::SetSpecial(const std::string &)
   */
  bool CNetAddr::IsTor() const { return m_net == NET_ONION; }
  
  /**
   * Check whether this object represents an I2P address.
   */
  bool CNetAddr::IsI2P() const { return m_net == NET_I2P; }
  
  /**
   * Check whether this object represents a CJDNS address.
   */
  bool CNetAddr::IsCJDNS() const { return m_net == NET_CJDNS; }
  
  bool CNetAddr::IsLocal() const
  {
      // IPv4 loopback (127.0.0.0/8 or 0.0.0.0/8)
      if (IsIPv4() && (m_addr[0] == 127 || m_addr[0] == 0)) {
          return true;
      }
  
      // IPv6 loopback (::1/128)
      static const unsigned char pchLocal[16] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1};
      if (IsIPv6() && memcmp(m_addr.data(), pchLocal, sizeof(pchLocal)) == 0) {
          return true;
      }
  
      return false;
  }
  
  /**
   * @returns Whether or not this network address is a valid address that @a could
   *          be used to refer to an actual host.
   *
   * @note A valid address may or may not be publicly routable on the global
   *       internet. As in, the set of valid addresses is a superset of the set of
   *       publicly routable addresses.
   *
   * @see CNetAddr::IsRoutable()
   */
  bool CNetAddr::IsValid() const
  {
      // unspecified IPv6 address (::/128)
      unsigned char ipNone6[16] = {};
      if (IsIPv6() && memcmp(m_addr.data(), ipNone6, sizeof(ipNone6)) == 0) {
          return false;
      }
  
      // documentation IPv6 address
      if (IsRFC3849())
          return false;
  
      if (IsInternal())
          return false;
  
      if (IsIPv4()) {
          const uint32_t addr = ReadBE32(m_addr.data());
          if (addr == INADDR_ANY || addr == INADDR_NONE) {
              return false;
          }
      }
  
      return true;
  }
  
  /**
   * @returns Whether or not this network address is publicly routable on the
   *          global internet.
   *
   * @note A routable address is always valid. As in, the set of routable addresses
   *       is a subset of the set of valid addresses.
   *
   * @see CNetAddr::IsValid()
   */
  bool CNetAddr::IsRoutable() const
  {
      return IsValid() && !(IsRFC1918() || IsRFC2544() || IsRFC3927() || IsRFC4862() || IsRFC6598() || IsRFC5737() || (IsRFC4193() && !IsTor()) || IsRFC4843() || IsRFC7343() || IsLocal() || IsInternal());
  }
  
  /**
   * @returns Whether or not this is a dummy address that represents a name.
   *
   * @see CNetAddr::SetInternal(const std::string &)
   */
  bool CNetAddr::IsInternal() const
  {
     return m_net == NET_INTERNAL;
  }
  
  bool CNetAddr::IsAddrV1Compatible() const
  {
      switch (m_net) {
      case NET_IPV4:
      case NET_IPV6:
      case NET_INTERNAL:
          return true;
      case NET_ONION:
          return m_addr.size() == ADDR_TORV2_SIZE;
      case NET_I2P:
      case NET_CJDNS:
          return false;
      case NET_UNROUTABLE: // m_net is never and should not be set to NET_UNROUTABLE
      case NET_MAX:        // m_net is never and should not be set to NET_MAX
          assert(false);
      } // no default case, so the compiler can warn about missing cases
  
      assert(false);
  }
  
  enum Network CNetAddr::GetNetwork() const
  {
      if (IsInternal())
          return NET_INTERNAL;
  
      if (!IsRoutable())
          return NET_UNROUTABLE;
  
      return m_net;
  }
  
  static std::string IPv6ToString(Span<const uint8_t> a)
  {
      assert(a.size() == ADDR_IPV6_SIZE);
      // clang-format off
      return strprintf("%x:%x:%x:%x:%x:%x:%x:%x",
                       ReadBE16(&a[0]),
                       ReadBE16(&a[2]),
                       ReadBE16(&a[4]),
                       ReadBE16(&a[6]),
                       ReadBE16(&a[8]),
                       ReadBE16(&a[10]),
                       ReadBE16(&a[12]),
                       ReadBE16(&a[14]));
      // clang-format on
  }
  
  std::string CNetAddr::ToStringIP() const
  {
      switch (m_net) {
      case NET_IPV4:
      case NET_IPV6: {
          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 (m_net == NET_IPV4) {
              return strprintf("%u.%u.%u.%u", m_addr[0], m_addr[1], m_addr[2], m_addr[3]);
          }
          return IPv6ToString(m_addr);
      }
      case NET_ONION:
          switch (m_addr.size()) {
          case ADDR_TORV2_SIZE:
              return EncodeBase32(m_addr) + ".onion";
          case ADDR_TORV3_SIZE: {
  
              uint8_t checksum[torv3::CHECKSUM_LEN];
              torv3::Checksum(m_addr, checksum);
  
              // TORv3 onion_address = base32(PUBKEY | CHECKSUM | VERSION) + ".onion"
              prevector<torv3::TOTAL_LEN, uint8_t> address{m_addr.begin(), m_addr.end()};
              address.insert(address.end(), checksum, checksum + torv3::CHECKSUM_LEN);
              address.insert(address.end(), torv3::VERSION, torv3::VERSION + sizeof(torv3::VERSION));
  
              return EncodeBase32(address) + ".onion";
          }
          default:
              assert(false);
          }
      case NET_I2P:
          return EncodeBase32(m_addr, false /* don't pad with = */) + ".b32.i2p";
      case NET_CJDNS:
          return IPv6ToString(m_addr);
      case NET_INTERNAL:
          return EncodeBase32(m_addr) + ".internal";
      case NET_UNROUTABLE: // m_net is never and should not be set to NET_UNROUTABLE
      case NET_MAX:        // m_net is never and should not be set to NET_MAX
          assert(false);
      } // no default case, so the compiler can warn about missing cases
  
      assert(false);
  }
  
  std::string CNetAddr::ToString() const
  {
      return ToStringIP();
  }
  
  bool operator==(const CNetAddr& a, const CNetAddr& b)
  {
      return a.m_net == b.m_net && a.m_addr == b.m_addr;
  }
  
  bool operator<(const CNetAddr& a, const CNetAddr& b)
  {
      return std::tie(a.m_net, a.m_addr) < std::tie(b.m_net, b.m_addr);
  }
  
  /**
   * Try to get our IPv4 address.
   *
   * @param[out] pipv4Addr The in_addr struct to which to copy.
   *
   * @returns Whether or not the operation was successful, in particular, whether
   *          or not our address was an IPv4 address.
   *
   * @see CNetAddr::IsIPv4()
   */
  bool CNetAddr::GetInAddr(struct in_addr* pipv4Addr) const
  {
      if (!IsIPv4())
          return false;
      assert(sizeof(*pipv4Addr) == m_addr.size());
      memcpy(pipv4Addr, m_addr.data(), m_addr.size());
      return true;
  }
  
  /**
   * Try to get our IPv6 address.
   *
   * @param[out] pipv6Addr The in6_addr struct to which to copy.
   *
   * @returns Whether or not the operation was successful, in particular, whether
   *          or not our address was an IPv6 address.
   *
   * @see CNetAddr::IsIPv6()
   */
  bool CNetAddr::GetIn6Addr(struct in6_addr* pipv6Addr) const
  {
      if (!IsIPv6()) {
          return false;
      }
      assert(sizeof(*pipv6Addr) == m_addr.size());
      memcpy(pipv6Addr, m_addr.data(), m_addr.size());
      return true;
  }
  
  bool CNetAddr::HasLinkedIPv4() const
  {
      return IsRoutable() && (IsIPv4() || IsRFC6145() || IsRFC6052() || IsRFC3964() || IsRFC4380());
  }
  
  uint32_t CNetAddr::GetLinkedIPv4() const
  {
      if (IsIPv4()) {
          return ReadBE32(m_addr.data());
      } else if (IsRFC6052() || IsRFC6145()) {
          // mapped IPv4, SIIT translated IPv4: the IPv4 address is the last 4 bytes of the address
          return ReadBE32(MakeSpan(m_addr).last(ADDR_IPV4_SIZE).data());
      } else if (IsRFC3964()) {
          // 6to4 tunneled IPv4: the IPv4 address is in bytes 2-6
          return ReadBE32(MakeSpan(m_addr).subspan(2, ADDR_IPV4_SIZE).data());
      } else if (IsRFC4380()) {
          // Teredo tunneled IPv4: the IPv4 address is in the last 4 bytes of the address, but bitflipped
          return ~ReadBE32(MakeSpan(m_addr).last(ADDR_IPV4_SIZE).data());
      }
      assert(false);
  }
  
  Network CNetAddr::GetNetClass() const
  {
      // Make sure that if we return NET_IPV6, then IsIPv6() is true. The callers expect that.
  
      // Check for "internal" first because such addresses are also !IsRoutable()
      // and we don't want to return NET_UNROUTABLE in that case.
      if (IsInternal()) {
          return NET_INTERNAL;
      }
      if (!IsRoutable()) {
          return NET_UNROUTABLE;
      }
      if (HasLinkedIPv4()) {
          return NET_IPV4;
      }
      return m_net;
  }
  
  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 (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 = 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(IsIPv6());
          for (int8_t byte_i = 0; byte_i < 16; ++byte_i) {
              uint8_t cur_byte = m_addr[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;
  }
  
  /**
   * 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.
   */
  std::vector<unsigned char> CNetAddr::GetGroup(const std::vector<bool> &asmap) const
  {
      std::vector<unsigned char> 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 nBits{0};
  
      if (IsLocal()) {
          // all local addresses belong to the same group
      } else if (IsInternal()) {
          // all internal-usage addresses get their own group
          nBits = ADDR_INTERNAL_SIZE * 8;
      } else if (!IsRoutable()) {
          // all other unroutable addresses belong to the same group
      } 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() || IsI2P() || IsCJDNS()) {
          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 address onto vchRet.
      const size_t num_bytes = nBits / 8;
      vchRet.insert(vchRet.end(), m_addr.begin(), m_addr.begin() + 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 < m_addr.size());
          vchRet.push_back(m_addr[num_bytes] | ((1 << (8 - nBits)) - 1));
      }
  
      return vchRet;
  }
  
  std::vector<unsigned char> CNetAddr::GetAddrBytes() const
  {
      if (IsAddrV1Compatible()) {
          uint8_t serialized[V1_SERIALIZATION_SIZE];
          SerializeV1Array(serialized);
          return {std::begin(serialized), std::end(serialized)};
      }
      return std::vector<unsigned char>(m_addr.begin(), m_addr.end());
  }
  
  uint64_t CNetAddr::GetHash() const
  {
      uint256 hash = Hash(m_addr);
      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;
  int static GetExtNetwork(const CNetAddr *addr)
  {
      if (addr == nullptr)
          return NET_UNKNOWN;
      if (addr->IsRFC4380())
          return NET_TEREDO;
      return addr->GetNetwork();
  }
  
  /** Calculates a metric for how reachable (*this) is from a given partner */
  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;
          case NET_IPV6:   return fTunnel ? REACH_IPV6_WEAK : REACH_IPV6_STRONG; // only prefer giving our IPv6 address if it's not tunnelled
          }
      case NET_ONION:
          switch(ourNet) {
          default:         return REACH_DEFAULT;
          case NET_IPV4:   return REACH_IPV4; // Tor users can connect to IPv4 as well
          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;
          case NET_ONION:     return REACH_PRIVATE; // either from Tor, or don't care about our address
          }
      }
  }
  
  CService::CService() : port(0)
  {
  }
  
  CService::CService(const CNetAddr& cip, uint16_t portIn) : CNetAddr(cip), port(portIn)
  {
  }
  
  CService::CService(const struct in_addr& ipv4Addr, uint16_t portIn) : CNetAddr(ipv4Addr), port(portIn)
  {
  }
  
  CService::CService(const struct in6_addr& ipv6Addr, uint16_t 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(*(const struct sockaddr_in*)paddr);
          return true;
      case AF_INET6:
          *this = CService(*(const struct sockaddr_in6*)paddr);
          return true;
      default:
          return false;
      }
  }
  
  uint16_t 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);
  }
  
  /**
   * Obtain the IPv4/6 socket address this represents.
   *
   * @param[out] paddr The obtained socket address.
   * @param[in,out] addrlen The size, in bytes, of the address structure pointed
   *                        to by paddr. The value that's pointed to by this
   *                        parameter might change after calling this function if
   *                        the size of the corresponding address structure
   *                        changed.
   *
   * @returns Whether or not the operation was successful.
   */
  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 = (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 = (struct sockaddr_in6*)paddr;
          memset(paddrin6, 0, *addrlen);
          if (!GetIn6Addr(&paddrin6->sin6_addr))
              return false;
          paddrin6->sin6_scope_id = m_scope_id;
          paddrin6->sin6_family = AF_INET6;
          paddrin6->sin6_port = htons(port);
          return true;
      }
      return false;
  }
  
  /**
   * @returns An identifier unique to this service's address and port number.
   */
  std::vector<unsigned char> CService::GetKey() const
  {
      auto key = GetAddrBytes();
      key.push_back(port / 0x100); // most significant byte of our port
      key.push_back(port & 0x0FF); // least significant byte of our port
      return key;
  }
  
  std::string CService::ToStringPort() const
  {
      return strprintf("%u", port);
  }
  
  std::string CService::ToStringIPPort() const
  {
      if (IsIPv4() || IsTor() || IsI2P() || 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, uint8_t mask) : CSubNet()
  {
      valid = (addr.IsIPv4() && mask <= ADDR_IPV4_SIZE * 8) ||
              (addr.IsIPv6() && mask <= ADDR_IPV6_SIZE * 8);
      if (!valid) {
          return;
      }
  
      assert(mask <= sizeof(netmask) * 8);
  
      network = addr;
  
      uint8_t n = mask;
      for (size_t i = 0; i < network.m_addr.size(); ++i) {
          const uint8_t bits = n < 8 ? n : 8;
          netmask[i] = (uint8_t)((uint8_t)0xFF << (8 - bits)); // Set first bits.
          network.m_addr[i] &= netmask[i]; // Normalize network according to netmask.
          n -= bits;
      }
  }
  
  /**
   * @returns The number of 1-bits in the prefix of the specified subnet mask. If
   *          the specified subnet mask is not a valid one, -1.
   */
  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;
      }
  }
  
  CSubNet::CSubNet(const CNetAddr& addr, const CNetAddr& mask) : CSubNet()
  {
      valid = (addr.IsIPv4() || addr.IsIPv6()) && addr.m_net == mask.m_net;
      if (!valid) {
          return;
      }
      // Check if `mask` contains 1-bits after 0-bits (which is an invalid netmask).
      bool zeros_found = false;
      for (auto b : mask.m_addr) {
          const int num_bits = NetmaskBits(b);
          if (num_bits == -1 || (zeros_found && num_bits != 0)) {
              valid = false;
              return;
          }
          if (num_bits < 8) {
              zeros_found = true;
          }
      }
  
      assert(mask.m_addr.size() <= sizeof(netmask));
  
      memcpy(netmask, mask.m_addr.data(), mask.m_addr.size());
  
      network = addr;
  
      // Normalize network according to netmask
      for (size_t x = 0; x < network.m_addr.size(); ++x) {
          network.m_addr[x] &= netmask[x];
      }
  }
  
  CSubNet::CSubNet(const CNetAddr& addr) : CSubNet()
  {
      valid = addr.IsIPv4() || addr.IsIPv6();
      if (!valid) {
          return;
      }
  
      assert(addr.m_addr.size() <= sizeof(netmask));
  
      memset(netmask, 0xFF, addr.m_addr.size());
  
      network = addr;
  }
  
  /**
   * @returns True if this subnet is valid, the specified address is valid, and
   *          the specified address belongs in this subnet.
   */
  bool CSubNet::Match(const CNetAddr &addr) const
  {
      if (!valid || !addr.IsValid() || network.m_net != addr.m_net)
          return false;
      assert(network.m_addr.size() == addr.m_addr.size());
      for (size_t x = 0; x < addr.m_addr.size(); ++x) {
          if ((addr.m_addr[x] & netmask[x]) != network.m_addr[x]) {
              return false;
          }
      }
      return true;
  }
  
  std::string CSubNet::ToString() const
  {
      assert(network.m_addr.size() <= sizeof(netmask));
  
      uint8_t cidr = 0;
  
      for (size_t i = 0; i < network.m_addr.size(); ++i) {
          if (netmask[i] == 0x00) {
              break;
          }
          cidr += NetmaskBits(netmask[i]);
      }
  
      return network.ToString() + strprintf("/%u", cidr);
  }
  
  bool CSubNet::IsValid() const
  {
      return valid;
  }
  
  bool CSubNet::SanityCheck() const
  {
      if (!(network.IsIPv4() || network.IsIPv6())) return false;
  
      for (size_t x = 0; x < network.m_addr.size(); ++x) {
          if (network.m_addr[x] & ~netmask[x]) return false;
      }
  
      return true;
  }
  
  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)
  {
      return SanityCheckASMap(asmap, 128); // For IP address lookups, the input is 128 bits
  }
  