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       1              : // Copyright (c) 2024 The Bitcoin Core developers
       2              : // Distributed under the MIT software license, see the accompanying
       3              : // file COPYING or https://www.opensource.org/licenses/mit-license.php.
       4              : 
       5              : #ifndef BITCOIN_COMMON_PCP_H
       6              : #define BITCOIN_COMMON_PCP_H
       7              : 
       8              : #include <netaddress.h>
       9              : 
      10              : #include <variant>
      11              : 
      12              : // RFC6886 NAT-PMP and RFC6887 Port Control Protocol (PCP) implementation.
      13              : // NAT-PMP and PCP use network byte order (big-endian).
      14              : 
      15              : //! Mapping nonce size in bytes (see RFC6887 section 11.1).
      16              : constexpr size_t PCP_MAP_NONCE_SIZE = 12;
      17              : 
      18              : //! PCP mapping nonce. Arbitrary data chosen by the client to identify a mapping.
      19              : typedef std::array<uint8_t, PCP_MAP_NONCE_SIZE> PCPMappingNonce;
      20              : 
      21              : //! Unsuccessful response to a port mapping.
      22              : enum class MappingError {
      23              :     NETWORK_ERROR,  ///< Any kind of network-level error.
      24              :     PROTOCOL_ERROR, ///< Any kind of protocol-level error, except unsupported version or no resources.
      25              :     UNSUPP_VERSION, ///< Unsupported protocol version.
      26              :     NO_RESOURCES,   ///< No resources available (port probably already mapped).
      27              : };
      28              : 
      29              : //! Successful response to a port mapping.
      30            0 : struct MappingResult {
      31            0 :     MappingResult(uint8_t version, const CService &internal_in, const CService &external_in, uint32_t lifetime_in):
      32            0 :         version(version), internal(internal_in), external(external_in), lifetime(lifetime_in) {}
      33              :     //! Protocol version, one of NATPMP_VERSION or PCP_VERSION.
      34              :     uint8_t version;
      35              :     //! Internal host:port.
      36              :     CService internal;
      37              :     //! External host:port.
      38              :     CService external;
      39              :     //! Granted lifetime of binding (seconds).
      40              :     uint32_t lifetime;
      41              : 
      42              :     //! Format mapping as string for logging.
      43              :     std::string ToString();
      44              : };
      45              : 
      46              : //! Try to open a port using RFC 6886 NAT-PMP. IPv4 only.
      47              : //!
      48              : //! * gateway: Destination address for PCP requests (usually the default gateway).
      49              : //! * port: Internal port, and desired external port.
      50              : //! * lifetime: Requested lifetime in seconds for mapping. The server may assign as shorter or longer lifetime. A lifetime of 0 deletes the mapping.
      51              : //! * num_tries: Number of tries in case of no response.
      52              : //!
      53              : //! Returns the external_ip:external_port of the mapping if successful, otherwise a MappingError.
      54              : std::variant<MappingResult, MappingError> NATPMPRequestPortMap(const CNetAddr &gateway, uint16_t port, uint32_t lifetime, int num_tries = 3, std::chrono::milliseconds timeout_per_try = std::chrono::milliseconds(1000));
      55              : 
      56              : //! Try to open a port using RFC 6887 Port Control Protocol (PCP). Handles IPv4 and IPv6.
      57              : //!
      58              : //! * nonce: Mapping cookie. Keep this the same over renewals.
      59              : //! * gateway: Destination address for PCP requests (usually the default gateway).
      60              : //! * bind: Specific local bind address for IPv6 pinholing. Set this as INADDR_ANY for IPv4.
      61              : //! * port: Internal port, and desired external port.
      62              : //! * lifetime: Requested lifetime in seconds for mapping. The server may assign as shorter or longer lifetime. A lifetime of 0 deletes the mapping.
      63              : //! * num_tries: Number of tries in case of no response.
      64              : //!
      65              : //! Returns the external_ip:external_port of the mapping if successful, otherwise a MappingError.
      66              : std::variant<MappingResult, MappingError> PCPRequestPortMap(const PCPMappingNonce &nonce, const CNetAddr &gateway, const CNetAddr &bind, uint16_t port, uint32_t lifetime, int num_tries = 3, std::chrono::milliseconds timeout_per_try = std::chrono::milliseconds(1000));
      67              : 
      68              : #endif // BITCOIN_COMMON_PCP_H