// Copyright (c) 2009-2020 The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.

#ifndef BITCOIN_NETADDRESS_H
#define BITCOIN_NETADDRESS_H

#if defined(HAVE_CONFIG_H)
#include <config/bitcoin-config.h>
#endif

#include <attributes.h>
#include <compat.h>
#include <prevector.h>
#include <serialize.h>
#include <tinyformat.h>
#include <util/strencodings.h>
#include <util/string.h>

#include <array>
#include <cstdint>
#include <ios>
#include <string>
#include <vector>

/**
 * A flag that is ORed into the protocol version to designate that addresses
 * should be serialized in (unserialized from) v2 format (BIP155).
 * Make sure that this does not collide with any of the values in `version.h`
 * or with `SERIALIZE_TRANSACTION_NO_WITNESS`.
 */
static constexpr int ADDRV2_FORMAT = 0x20000000;

/**
 * A network type.
 * @note An address may belong to more than one network, for example `10.0.0.1`
 * belongs to both `NET_UNROUTABLE` and `NET_IPV4`.
 * Keep these sequential starting from 0 and `NET_MAX` as the last entry.
 * We have loops like `for (int i = 0; i < NET_MAX; i++)` that expect to iterate
 * over all enum values and also `GetExtNetwork()` "extends" this enum by
 * introducing standalone constants starting from `NET_MAX`.
 */
enum Network
{
    /// Addresses from these networks are not publicly routable on the global Internet.
    NET_UNROUTABLE = 0,

    /// IPv4
    NET_IPV4,

    /// IPv6
    NET_IPV6,

    /// TOR (v2 or v3)
    NET_ONION,

    /// I2P
    NET_I2P,

    /// CJDNS
    NET_CJDNS,

    /// A set of addresses that represent the hash of a string or FQDN. We use
    /// them in CAddrMan to keep track of which DNS seeds were used.
    NET_INTERNAL,

    /// Dummy value to indicate the number of NET_* constants.
    NET_MAX,
};

/// Prefix of an IPv6 address when it contains an embedded IPv4 address.
/// Used when (un)serializing addresses in ADDRv1 format (pre-BIP155).
static const std::array<uint8_t, 12> IPV4_IN_IPV6_PREFIX{
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xFF, 0xFF
};

/// Prefix of an IPv6 address when it contains an embedded TORv2 address.
/// Used when (un)serializing addresses in ADDRv1 format (pre-BIP155).
/// Such dummy IPv6 addresses are guaranteed to not be publicly routable as they
/// fall under RFC4193's fc00::/7 subnet allocated to unique-local addresses.
static const std::array<uint8_t, 6> TORV2_IN_IPV6_PREFIX{
    0xFD, 0x87, 0xD8, 0x7E, 0xEB, 0x43
};

/// Prefix of an IPv6 address when it contains an embedded "internal" address.
/// Used when (un)serializing addresses in ADDRv1 format (pre-BIP155).
/// The prefix comes from 0xFD + SHA256("bitcoin")[0:5].
/// Such dummy IPv6 addresses are guaranteed to not be publicly routable as they
/// fall under RFC4193's fc00::/7 subnet allocated to unique-local addresses.
static const std::array<uint8_t, 6> INTERNAL_IN_IPV6_PREFIX{
    0xFD, 0x6C, 0xE9, 0xFE, 0x45, 0x49 // 0xFD + sha256("litecoin")[0:5].
};

/// Size of IPv4 address (in bytes).
static constexpr size_t ADDR_IPV4_SIZE = 4;

/// Size of IPv6 address (in bytes).
static constexpr size_t ADDR_IPV6_SIZE = 16;

/// Size of TORv2 address (in bytes).
static constexpr size_t ADDR_TORV2_SIZE = 10;

/// Size of TORv3 address (in bytes). This is the length of just the address
/// as used in BIP155, without the checksum and the version byte.
static constexpr size_t ADDR_TORV3_SIZE = 32;

/// Size of I2P address (in bytes).
static constexpr size_t ADDR_I2P_SIZE = 32;

/// Size of CJDNS address (in bytes).
static constexpr size_t ADDR_CJDNS_SIZE = 16;

/// Size of "internal" (NET_INTERNAL) address (in bytes).
static constexpr size_t ADDR_INTERNAL_SIZE = 10;

/**
 * Network address.
 */
class CNetAddr
{
    protected:
        /**
         * Raw representation of the network address.
         * In network byte order (big endian) for IPv4 and IPv6.
         */
        prevector<ADDR_IPV6_SIZE, uint8_t> m_addr{ADDR_IPV6_SIZE, 0x0};

        /**
         * Network to which this address belongs.
         */
        Network m_net{NET_IPV6};

        /**
         * Scope id if scoped/link-local IPV6 address.
         * See https://tools.ietf.org/html/rfc4007
         */
        uint32_t m_scope_id{0};

    public:
        CNetAddr();
        explicit CNetAddr(const struct in_addr& ipv4Addr);
        void SetIP(const CNetAddr& ip);

        /**
         * Set from a legacy IPv6 address.
         * Legacy IPv6 address may be a normal IPv6 address, or another address
         * (e.g. IPv4) disguised as IPv6. This encoding is used in the legacy
         * `addr` encoding.
         */
        void SetLegacyIPv6(Span<const uint8_t> ipv6);

        bool SetInternal(const std::string& name);

        bool SetSpecial(const std::string &strName); // for Tor addresses
        bool IsBindAny() const; // INADDR_ANY equivalent
        bool IsIPv4() const;    // IPv4 mapped address (::FFFF:0:0/96, 0.0.0.0/0)
        bool IsIPv6() const;    // IPv6 address (not mapped IPv4, not Tor)
        bool IsRFC1918() const; // IPv4 private networks (10.0.0.0/8, 192.168.0.0/16, 172.16.0.0/12)
        bool IsRFC2544() const; // IPv4 inter-network communications (198.18.0.0/15)
        bool IsRFC6598() const; // IPv4 ISP-level NAT (100.64.0.0/10)
        bool IsRFC5737() const; // IPv4 documentation addresses (192.0.2.0/24, 198.51.100.0/24, 203.0.113.0/24)
        bool IsRFC3849() const; // IPv6 documentation address (2001:0DB8::/32)
        bool IsRFC3927() const; // IPv4 autoconfig (169.254.0.0/16)
        bool IsRFC3964() const; // IPv6 6to4 tunnelling (2002::/16)
        bool IsRFC4193() const; // IPv6 unique local (FC00::/7)
        bool IsRFC4380() const; // IPv6 Teredo tunnelling (2001::/32)
        bool IsRFC4843() const; // IPv6 ORCHID (deprecated) (2001:10::/28)
        bool IsRFC7343() const; // IPv6 ORCHIDv2 (2001:20::/28)
        bool IsRFC4862() const; // IPv6 autoconfig (FE80::/64)
        bool IsRFC6052() const; // IPv6 well-known prefix for IPv4-embedded address (64:FF9B::/96)
        bool IsRFC6145() const; // IPv6 IPv4-translated address (::FFFF:0:0:0/96) (actually defined in RFC2765)
        bool IsHeNet() const;   // IPv6 Hurricane Electric - https://he.net (2001:0470::/36)
        bool IsTor() const;
        bool IsI2P() const;
        bool IsCJDNS() const;
        bool IsLocal() const;
        bool IsRoutable() const;
        bool IsInternal() const;
        bool IsValid() const;

        /**
         * Check if the current object can be serialized in pre-ADDRv2/BIP155 format.
         */
        bool IsAddrV1Compatible() const;

        enum Network GetNetwork() const;
        std::string ToString() const;
        std::string ToStringIP() const;
        uint64_t GetHash() const;
        bool GetInAddr(struct in_addr* pipv4Addr) const;
        Network GetNetClass() const;

        //! For IPv4, mapped IPv4, SIIT translated IPv4, Teredo, 6to4 tunneled addresses, return the relevant IPv4 address as a uint32.
        uint32_t GetLinkedIPv4() const;
        //! Whether this address has a linked IPv4 address (see GetLinkedIPv4()).
        bool HasLinkedIPv4() const;

        // The AS on the BGP path to the node we use to diversify
        // peers in AddrMan bucketing based on the AS infrastructure.
        // The ip->AS mapping depends on how asmap is constructed.
        uint32_t GetMappedAS(const std::vector<bool> &asmap) const;

        std::vector<unsigned char> GetGroup(const std::vector<bool> &asmap) const;
        std::vector<unsigned char> GetAddrBytes() const;
        int GetReachabilityFrom(const CNetAddr *paddrPartner = nullptr) const;

        explicit CNetAddr(const struct in6_addr& pipv6Addr, const uint32_t scope = 0);
        bool GetIn6Addr(struct in6_addr* pipv6Addr) const;

        friend bool operator==(const CNetAddr& a, const CNetAddr& b);
        friend bool operator!=(const CNetAddr& a, const CNetAddr& b) { return !(a == b); }
        friend bool operator<(const CNetAddr& a, const CNetAddr& b);

        /**
         * Whether this address should be relayed to other peers even if we can't reach it ourselves.
         */
        bool IsRelayable() const
        {
            return IsIPv4() || IsIPv6() || IsTor();
        }

        /**
         * Serialize to a stream.
         */
        template <typename Stream>
        void Serialize(Stream& s) const
        {
            if (s.GetVersion() & ADDRV2_FORMAT) {
                SerializeV2Stream(s);
            } else {
                SerializeV1Stream(s);
            }
        }

        /**
         * Unserialize from a stream.
         */
        template <typename Stream>
        void Unserialize(Stream& s)
        {
            if (s.GetVersion() & ADDRV2_FORMAT) {
                UnserializeV2Stream(s);
            } else {
                UnserializeV1Stream(s);
            }
        }

        friend class CSubNet;

    private:
        /**
         * BIP155 network ids recognized by this software.
         */
        enum BIP155Network : uint8_t {
            IPV4 = 1,
            IPV6 = 2,
            TORV2 = 3,
            TORV3 = 4,
            I2P = 5,
            CJDNS = 6,
        };

        /**
         * Size of CNetAddr when serialized as ADDRv1 (pre-BIP155) (in bytes).
         */
        static constexpr size_t V1_SERIALIZATION_SIZE = ADDR_IPV6_SIZE;

        /**
         * Maximum size of an address as defined in BIP155 (in bytes).
         * This is only the size of the address, not the entire CNetAddr object
         * when serialized.
         */
        static constexpr size_t MAX_ADDRV2_SIZE = 512;

        /**
         * Get the BIP155 network id of this address.
         * Must not be called for IsInternal() objects.
         * @returns BIP155 network id
         */
        BIP155Network GetBIP155Network() const;

        /**
         * Set `m_net` from the provided BIP155 network id and size after validation.
         * @retval true the network was recognized, is valid and `m_net` was set
         * @retval false not recognised (from future?) and should be silently ignored
         * @throws std::ios_base::failure if the network is one of the BIP155 founding
         * networks (id 1..6) with wrong address size.
         */
        bool SetNetFromBIP155Network(uint8_t possible_bip155_net, size_t address_size);

        /**
         * Serialize in pre-ADDRv2/BIP155 format to an array.
         */
        void SerializeV1Array(uint8_t (&arr)[V1_SERIALIZATION_SIZE]) const
        {
            size_t prefix_size;

            switch (m_net) {
            case NET_IPV6:
                assert(m_addr.size() == sizeof(arr));
                memcpy(arr, m_addr.data(), m_addr.size());
                return;
            case NET_IPV4:
                prefix_size = sizeof(IPV4_IN_IPV6_PREFIX);
                assert(prefix_size + m_addr.size() == sizeof(arr));
                memcpy(arr, IPV4_IN_IPV6_PREFIX.data(), prefix_size);
                memcpy(arr + prefix_size, m_addr.data(), m_addr.size());
                return;
            case NET_ONION:
                if (m_addr.size() == ADDR_TORV3_SIZE) {
                    break;
                }
                prefix_size = sizeof(TORV2_IN_IPV6_PREFIX);
                assert(prefix_size + m_addr.size() == sizeof(arr));
                memcpy(arr, TORV2_IN_IPV6_PREFIX.data(), prefix_size);
                memcpy(arr + prefix_size, m_addr.data(), m_addr.size());
                return;
            case NET_INTERNAL:
                prefix_size = sizeof(INTERNAL_IN_IPV6_PREFIX);
                assert(prefix_size + m_addr.size() == sizeof(arr));
                memcpy(arr, INTERNAL_IN_IPV6_PREFIX.data(), prefix_size);
                memcpy(arr + prefix_size, m_addr.data(), m_addr.size());
                return;
            case NET_I2P:
                break;
            case NET_CJDNS:
                break;
            case NET_UNROUTABLE:
            case NET_MAX:
                assert(false);
            } // no default case, so the compiler can warn about missing cases

            // Serialize TORv3, I2P and CJDNS as all-zeros.
            memset(arr, 0x0, V1_SERIALIZATION_SIZE);
        }

        /**
         * Serialize in pre-ADDRv2/BIP155 format to a stream.
         */
        template <typename Stream>
        void SerializeV1Stream(Stream& s) const
        {
            uint8_t serialized[V1_SERIALIZATION_SIZE];

            SerializeV1Array(serialized);

            s << serialized;
        }

        /**
         * Serialize as ADDRv2 / BIP155.
         */
        template <typename Stream>
        void SerializeV2Stream(Stream& s) const
        {
            if (IsInternal()) {
                // Serialize NET_INTERNAL as embedded in IPv6. We need to
                // serialize such addresses from addrman.
                s << static_cast<uint8_t>(BIP155Network::IPV6);
                s << COMPACTSIZE(ADDR_IPV6_SIZE);
                SerializeV1Stream(s);
                return;
            }

            s << static_cast<uint8_t>(GetBIP155Network());
            s << m_addr;
        }

        /**
         * Unserialize from a pre-ADDRv2/BIP155 format from an array.
         */
        void UnserializeV1Array(uint8_t (&arr)[V1_SERIALIZATION_SIZE])
        {
            // Use SetLegacyIPv6() so that m_net is set correctly. For example
            // ::FFFF:0102:0304 should be set as m_net=NET_IPV4 (1.2.3.4).
            SetLegacyIPv6(arr);
        }

        /**
         * Unserialize from a pre-ADDRv2/BIP155 format from a stream.
         */
        template <typename Stream>
        void UnserializeV1Stream(Stream& s)
        {
            uint8_t serialized[V1_SERIALIZATION_SIZE];

            s >> serialized;

            UnserializeV1Array(serialized);
        }

        /**
         * Unserialize from a ADDRv2 / BIP155 format.
         */
        template <typename Stream>
        void UnserializeV2Stream(Stream& s)
        {
            uint8_t bip155_net;
            s >> bip155_net;

            size_t address_size;
            s >> COMPACTSIZE(address_size);

            if (address_size > MAX_ADDRV2_SIZE) {
                throw std::ios_base::failure(strprintf(
                    "Address too long: %u > %u", address_size, MAX_ADDRV2_SIZE));
            }

            m_scope_id = 0;

            if (SetNetFromBIP155Network(bip155_net, address_size)) {
                m_addr.resize(address_size);
                s >> MakeSpan(m_addr);

                if (m_net != NET_IPV6) {
                    return;
                }

                // Do some special checks on IPv6 addresses.

                // Recognize NET_INTERNAL embedded in IPv6, such addresses are not
                // gossiped but could be coming from addrman, when unserializing from
                // disk.
                if (HasPrefix(m_addr, INTERNAL_IN_IPV6_PREFIX)) {
                    m_net = NET_INTERNAL;
                    memmove(m_addr.data(), m_addr.data() + INTERNAL_IN_IPV6_PREFIX.size(),
                            ADDR_INTERNAL_SIZE);
                    m_addr.resize(ADDR_INTERNAL_SIZE);
                    return;
                }

                if (!HasPrefix(m_addr, IPV4_IN_IPV6_PREFIX) &&
                    !HasPrefix(m_addr, TORV2_IN_IPV6_PREFIX)) {
                    return;
                }

                // IPv4 and TORv2 are not supposed to be embedded in IPv6 (like in V1
                // encoding). Unserialize as !IsValid(), thus ignoring them.
            } else {
                // If we receive an unknown BIP155 network id (from the future?) then
                // ignore the address - unserialize as !IsValid().
                s.ignore(address_size);
            }

            // Mimic a default-constructed CNetAddr object which is !IsValid() and thus
            // will not be gossiped, but continue reading next addresses from the stream.
            m_net = NET_IPV6;
            m_addr.assign(ADDR_IPV6_SIZE, 0x0);
        }
};

class CSubNet
{
    protected:
        /// Network (base) address
        CNetAddr network;
        /// Netmask, in network byte order
        uint8_t netmask[16];
        /// Is this value valid? (only used to signal parse errors)
        bool valid;

        bool SanityCheck() const;

    public:
        /**
         * Construct an invalid subnet (empty, `Match()` always returns false).
         */
        CSubNet();

        /**
         * Construct from a given network start and number of bits (CIDR mask).
         * @param[in] addr Network start. Must be IPv4 or IPv6, otherwise an invalid subnet is
         * created.
         * @param[in] mask CIDR mask, must be in [0, 32] for IPv4 addresses and in [0, 128] for
         * IPv6 addresses. Otherwise an invalid subnet is created.
         */
        CSubNet(const CNetAddr& addr, uint8_t mask);

        /**
         * Construct from a given network start and mask.
         * @param[in] addr Network start. Must be IPv4 or IPv6, otherwise an invalid subnet is
         * created.
         * @param[in] mask Network mask, must be of the same type as `addr` and not contain 0-bits
         * followed by 1-bits. Otherwise an invalid subnet is created.
         */
        CSubNet(const CNetAddr& addr, const CNetAddr& mask);

        /**
         * Construct a single-host subnet.
         * @param[in] addr The sole address to be contained in the subnet, can also be non-IPv[46].
         */
        explicit CSubNet(const CNetAddr& addr);

        bool Match(const CNetAddr &addr) const;

        std::string ToString() const;
        bool IsValid() const;

        friend bool operator==(const CSubNet& a, const CSubNet& b);
        friend bool operator!=(const CSubNet& a, const CSubNet& b) { return !(a == b); }
        friend bool operator<(const CSubNet& a, const CSubNet& b);

        SERIALIZE_METHODS(CSubNet, obj)
        {
            READWRITE(obj.network);
            if (obj.network.IsIPv4()) {
                // Before commit 102867c587f5f7954232fb8ed8e85cda78bb4d32, CSubNet used the last 4 bytes of netmask
                // to store the relevant bytes for an IPv4 mask. For compatiblity reasons, keep doing so in
                // serialized form.
                unsigned char dummy[12] = {0};
                READWRITE(dummy);
                READWRITE(MakeSpan(obj.netmask).first(4));
            } else {
                READWRITE(obj.netmask);
            }
            READWRITE(obj.valid);
            // Mark invalid if the result doesn't pass sanity checking.
            SER_READ(obj, if (obj.valid) obj.valid = obj.SanityCheck());
        }
};

/** A combination of a network address (CNetAddr) and a (TCP) port */
class CService : public CNetAddr
{
    protected:
        uint16_t port; // host order

    public:
        CService();
        CService(const CNetAddr& ip, uint16_t port);
        CService(const struct in_addr& ipv4Addr, uint16_t port);
        explicit CService(const struct sockaddr_in& addr);
        uint16_t GetPort() const;
        bool GetSockAddr(struct sockaddr* paddr, socklen_t *addrlen) const;
        bool SetSockAddr(const struct sockaddr* paddr);
        friend bool operator==(const CService& a, const CService& b);
        friend bool operator!=(const CService& a, const CService& b) { return !(a == b); }
        friend bool operator<(const CService& a, const CService& b);
        std::vector<unsigned char> GetKey() const;
        std::string ToString() const;
        std::string ToStringPort() const;
        std::string ToStringIPPort() const;

        CService(const struct in6_addr& ipv6Addr, uint16_t port);
        explicit CService(const struct sockaddr_in6& addr);

        SERIALIZE_METHODS(CService, obj)
        {
            READWRITEAS(CNetAddr, obj);
            READWRITE(Using<BigEndianFormatter<2>>(obj.port));
        }
};

bool SanityCheckASMap(const std::vector<bool>& asmap);

#endif // BITCOIN_NETADDRESS_H
