// Copyright (c) 2009-2016 The Bitcoin Core developers
// Copyright (c) 2017-2026 The Bitcoin developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.

#pragma once

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

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

#include <array>
#include <cstdint>
#include <cstring>
#include <functional>
#include <ios>
#include <optional>
#include <string>
#include <type_traits>
#include <utility>
#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`.
 */
inline 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).
inline constexpr 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.
inline constexpr 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.
inline constexpr std::array<uint8_t, 6> INTERNAL_IN_IPV6_PREFIX{{
    0xFD, 0x6B, 0x88, 0xC0, 0x87, 0x24 // 0xFD + sha256("bitcoin")[0:5].
}};

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

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

/// Size of TORv2 address (in bytes).
inline 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.
inline constexpr size_t ADDR_TORV3_SIZE = 32;

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

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

/// Size of "internal" (NET_INTERNAL) address (in bytes).
inline 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};

    // for scoped/link-local ipv6 addresses
    uint32_t scopeId{0};

public:
    /**
     * Construct an unspecified IPv6 network address (::/128).
     *
     * @note This address is considered invalid by CNetAddr::IsValid()
     */
    CNetAddr() noexcept {}
    explicit CNetAddr(const struct in_addr &ipv4Addr);
    explicit CNetAddr(const struct in6_addr &pipv6Addr, const uint32_t scope = 0);

    void SetIP(const CNetAddr &ip);

    void SetLegacyIPv6(Span<const uint8_t> ipv6);

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

    // for Tor addresses
    bool SetSpecial(const std::string &strName);
    // INADDR_ANY equivalent
    bool IsBindAny() const;
    // IPv4 mapped address (::FFFF:0:0/96, 0.0.0.0/0)
    bool IsIPv4() const;
    // IPv6 address (not mapped IPv4, not Tor)
    bool IsIPv6() const;
    // IPv4 private networks (10.0.0.0/8, 192.168.0.0/16, 172.16.0.0/12)
    bool IsRFC1918() const;
    // IPv4 inter-network communications (192.18.0.0/15)
    bool IsRFC2544() const;
    // IPv4 ISP-level NAT (100.64.0.0/10)
    bool IsRFC6598() const;
    // IPv4 documentation addresses (192.0.2.0/24, 198.51.100.0/24,
    // 203.0.113.0/24)
    bool IsRFC5737() const;
    // IPv6 documentation address (2001:0DB8::/32)
    bool IsRFC3849() const;
    // IPv4 autoconfig (169.254.0.0/16)
    bool IsRFC3927() const;
    // IPv6 6to4 tunnelling (2002::/16)
    bool IsRFC3964() const;
    // IPv6 unique local (FC00::/7)
    bool IsRFC4193() const;
    // IPv6 Teredo tunnelling (2001::/32)
    bool IsRFC4380() const;
    // IPv6 ORCHID (deprecated) (2001:10::/28)
    bool IsRFC4843() const;
    // IPv6 ORCHIDv2 (2001:20::/28)
    bool IsRFC7343() const;
    // IPv6 autoconfig (FE80::/64)
    bool IsRFC4862() const;
    // IPv6 well-known prefix for IPv4-embedded address (64:FF9B::/96)
    bool IsRFC6052() const;
    // IPv6 IPv4-translated address (::FFFF:0:0:0/96) (actually defined in RFC2765)
    bool IsRFC6145() const;
    // IPv6 Hurricane Electric - https://he.net (2001:0470::/36)
    bool IsHeNet() const;
    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;

    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<uint8_t> GetGroup(const std::vector<bool> &asmap) const;
    // This will return the address as a serialized V1 vector (size: 16 bytes).
    std::vector<uint8_t> GetAddrBytes() const;
    int GetReachabilityFrom(const CNetAddr *paddrPartner = nullptr) const;

    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);

    /**
     * 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.
     * Some addresses (e.g. TORv3) cannot be serialized in pre-BIP155 format.
     */
    std::array<uint8_t, V1_SERIALIZATION_SIZE> SerializeV1Array() const {
        std::array<uint8_t, V1_SERIALIZATION_SIZE> arr;

        switch (m_net) {
            case NET_IPV6:
                assert(m_addr.size() == arr.size());
                std::memcpy(arr.data(), m_addr.data(), m_addr.size());
                return arr;
            case NET_IPV4: {
                const size_t prefix_size = IPV4_IN_IPV6_PREFIX.size();
                assert(prefix_size + m_addr.size() == arr.size());
                std::memcpy(arr.data(), IPV4_IN_IPV6_PREFIX.data(), prefix_size);
                std::memcpy(arr.data() + prefix_size, m_addr.data(), m_addr.size());
                return arr;
            }
            case NET_ONION:
                if (m_addr.size() == ADDR_TORV3_SIZE) {
                    // Serialize TORv3 as all-zeros.
                    arr.fill(0);
                } else {
                    const size_t prefix_size = TORV2_IN_IPV6_PREFIX.size();
                    assert(prefix_size + m_addr.size() == arr.size());
                    std::memcpy(arr.data(), TORV2_IN_IPV6_PREFIX.data(), prefix_size);
                    std::memcpy(arr.data() + prefix_size, m_addr.data(), m_addr.size());
                }
                return arr;
            case NET_INTERNAL: {
                const size_t prefix_size = INTERNAL_IN_IPV6_PREFIX.size();
                assert(prefix_size + m_addr.size() == arr.size());
                std::memcpy(arr.data(), INTERNAL_IN_IPV6_PREFIX.data(), prefix_size);
                std::memcpy(arr.data() + prefix_size, m_addr.data(), m_addr.size());
                return arr;
            }
            case NET_I2P:
            case NET_CJDNS:
                // Serialize I2P and CJDNS as all-zeros.
                arr.fill(0);
                return arr;
            case NET_UNROUTABLE:
            case NET_MAX:
                break;
        } // no default case, so the compiler can warn about missing cases

        assert(false);
        return arr; // not reached
    }

    /**
     * Serialize in pre-ADDRv2/BIP155 format to a stream.
     */
    template <typename Stream>
    void SerializeV1Stream(Stream &s) const {
        // We write the contents "as if" it were a direct array (fixed size, no compactsize preamble).
        s << SerializeV1Array();
    }

    /**
     * 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 a vector. Note the supplied Span *MUST* be
     * V1_SERIALIZATION_SIZE bytes in size (16 bytes).
     */
    void UnserializeV1Array(Span<const uint8_t> data) {
        // 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(data);
    }

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

        // Direct array (fixed size, no compactsize preamble).
        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));
        }

        scopeId = 0;

        if (SetNetFromBIP155Network(bip155_net, address_size)) {
            m_addr.resize(address_size);
            s >> Span{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;
                // Delete the serialized "INTERNAL" prefix since we don't store it in memory.
                m_addr.erase(m_addr.begin(), m_addr.begin() + INTERNAL_IN_IPV6_PREFIX.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;

    /// Returns the CIDR length e.g. 0, 8, 12, 16, 24, etc
    uint8_t GetCIDRLength() const;

public:
    CSubNet() noexcept : netmask{0}, valid{false} {}
    CSubNet(const CNetAddr &addr, uint8_t mask);
    CSubNet(const CNetAddr &addr, const CNetAddr &mask);

    // constructor for single ip subnet (<ipv4>/32 or <ipv6>/128)
    explicit CSubNet(const CNetAddr &addr);

    bool Match(const CNetAddr &addr) const;

    std::string ToString() const;
    constexpr bool IsValid() const { return valid; }
    // returns true if this is a single ip subnet (<ipv4>/32 or <ipv6>/128)
    bool IsSingleIP() const;

    constexpr const CNetAddr & Network() const { return network; }

    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);

    /// Return the (prefix as CNetAddr, mask length)
    std::pair<CNetAddr, uint8_t> GetCIDR() const;

    SERIALIZE_METHODS(CSubNet, obj) {
        READWRITE(obj.network);
        if (obj.network.IsIPv4()) {
            // Before commit 084265a60d79740d7ee8fa04b4d315ef71c1c21f, 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.
            uint8_t dummy[12] = {0};
            READWRITE(dummy);
            READWRITE(MakeUInt8Span(obj.netmask).first(4));
            // TODO: replace the above with READWRITE(Span{obj.netmask}.first(4)); MakeUInt8Span is currently only needed due to a Clang bug: https://bugs.llvm.org/show_bug.cgi?id=39663 / https://stackoverflow.com/a/53619324/1678468
        } 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:
    // host order
    uint16_t port{0};

public:
    CService() noexcept = default;
    CService(const CNetAddr &cip, unsigned short portIn)
        : CNetAddr(cip), port(portIn) {}
    CService(const struct in_addr &ipv4Addr, unsigned short portIn)
        : CNetAddr(ipv4Addr), port(portIn) {}
    CService(const struct in6_addr &ipv6Addr, unsigned short portIn)
        : CNetAddr(ipv6Addr), port(portIn) {}
    explicit CService(const struct sockaddr_in6 &addr);
    explicit CService(const struct sockaddr_in &addr);

    constexpr uint16_t GetPort() const { return port; }
    std::optional<std::pair<sockaddr_storage, socklen_t>> GetSockAddr() const;
    bool SetSockAddr(const sockaddr_storage &addr);
    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<uint8_t> GetKey() const;
    std::string ToString() const;
    std::string ToStringPort() const;
    std::string ToStringIPPort() const;

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

// std::unordered_map & std::unordered_set support
struct SaltedNetAddrHasher : SaltedHasherBase {
    SaltedNetAddrHasher() noexcept {} // circumvent some libstdc++-11 bugs on Debian unstable
    size_t operator()(const CNetAddr &) const;
};
struct SaltedSubNetHasher : SaltedHasherBase {
    SaltedSubNetHasher() noexcept {} // circumvent some libstdc++-11 bugs on Debian unstable
    size_t operator()(const CSubNet  &) const;
};

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