interface tcp {
	use wasi:io/streams@0.2.0-rc-2023-10-18.{input-stream, output-stream};
	use wasi:io/poll@0.2.0-rc-2023-10-18.{pollable};
	use network.{network, error-code, ip-socket-address, ip-address-family};

	enum shutdown-type {
		/// Similar to `SHUT_RD` in POSIX.
		receive,

		/// Similar to `SHUT_WR` in POSIX.
		send,

		/// Similar to `SHUT_RDWR` in POSIX.
		both,
	}


	/// A TCP socket handle.
	resource tcp-socket {
		/// Bind the socket to a specific network on the provided IP address and port.
		///
		/// If the IP address is zero (`0.0.0.0` in IPv4, `::` in IPv6), it is left to the implementation to decide which
		/// network interface(s) to bind to.
		/// If the TCP/UDP port is zero, the socket will be bound to a random free port.
		///
		/// When a socket is not explicitly bound, the first invocation to a listen or connect operation will
		/// implicitly bind the socket.
		///
		/// Unlike in POSIX, this function is async. This enables interactive WASI hosts to inject permission prompts.
		///
		/// # Typical `start` errors
		/// - `invalid-argument`:          The `local-address` has the wrong address family. (EAFNOSUPPORT, EFAULT on Windows)
		/// - `invalid-argument`:          `local-address` is not a unicast address. (EINVAL)
		/// - `invalid-argument`:          `local-address` is an IPv4-mapped IPv6 address, but the socket has `ipv6-only` enabled. (EINVAL)
		/// - `invalid-state`:             The socket is already bound. (EINVAL)
		///
		/// # Typical `finish` errors
		/// - `address-in-use`:            No ephemeral ports available. (EADDRINUSE, ENOBUFS on Windows)
		/// - `address-in-use`:            Address is already in use. (EADDRINUSE)
		/// - `address-not-bindable`:      `local-address` is not an address that the `network` can bind to. (EADDRNOTAVAIL)
		/// - `not-in-progress`:           A `bind` operation is not in progress.
		/// - `would-block`:               Can't finish the operation, it is still in progress. (EWOULDBLOCK, EAGAIN)
		///
		/// # References
		/// - <https://pubs.opengroup.org/onlinepubs/9699919799/functions/bind.html>
		/// - <https://man7.org/linux/man-pages/man2/bind.2.html>
		/// - <https://learn.microsoft.com/en-us/windows/win32/api/winsock/nf-winsock-bind>
		/// - <https://man.freebsd.org/cgi/man.cgi?query=bind&sektion=2&format=html>
		start-bind: func(network: borrow<network>, local-address: ip-socket-address) -> result<_, error-code>;
		finish-bind: func() -> result<_, error-code>;

		/// Connect to a remote endpoint.
		///
		/// On success:
		/// - the socket is transitioned into the Connection state
		/// - a pair of streams is returned that can be used to read & write to the connection
		///
		/// POSIX mentions:
		/// > If connect() fails, the state of the socket is unspecified. Conforming applications should
		/// > close the file descriptor and create a new socket before attempting to reconnect.
		///
		/// WASI prescribes the following behavior:
		/// - If `connect` fails because an input/state validation error, the socket should remain usable.
		/// - If a connection was actually attempted but failed, the socket should become unusable for further network communication.
		///   Besides `drop`, any method after such a failure may return an error.
		///
		/// # Typical `start` errors
		/// - `invalid-argument`:          The `remote-address` has the wrong address family. (EAFNOSUPPORT)
		/// - `invalid-argument`:          `remote-address` is not a unicast address. (EINVAL, ENETUNREACH on Linux, EAFNOSUPPORT on MacOS)
		/// - `invalid-argument`:          `remote-address` is an IPv4-mapped IPv6 address, but the socket has `ipv6-only` enabled. (EINVAL, EADDRNOTAVAIL on Illumos)
		/// - `invalid-argument`:          `remote-address` is a non-IPv4-mapped IPv6 address, but the socket was bound to a specific IPv4-mapped IPv6 address. (or vice versa)
		/// - `invalid-argument`:          The IP address in `remote-address` is set to INADDR_ANY (`0.0.0.0` / `::`). (EADDRNOTAVAIL on Windows)
		/// - `invalid-argument`:          The port in `remote-address` is set to 0. (EADDRNOTAVAIL on Windows)
		/// - `invalid-argument`:          The socket is already attached to a different network. The `network` passed to `connect` must be identical to the one passed to `bind`.
		/// - `invalid-state`:             The socket is already in the Connection state. (EISCONN)
		/// - `invalid-state`:             The socket is already in the Listener state. (EOPNOTSUPP, EINVAL on Windows)
		///
		/// # Typical `finish` errors
		/// - `timeout`:                   Connection timed out. (ETIMEDOUT)
		/// - `connection-refused`:        The connection was forcefully rejected. (ECONNREFUSED)
		/// - `connection-reset`:          The connection was reset. (ECONNRESET)
		/// - `connection-aborted`:        The connection was aborted. (ECONNABORTED)
		/// - `remote-unreachable`:        The remote address is not reachable. (EHOSTUNREACH, EHOSTDOWN, ENETUNREACH, ENETDOWN)
		/// - `address-in-use`:            Tried to perform an implicit bind, but there were no ephemeral ports available. (EADDRINUSE, EADDRNOTAVAIL on Linux, EAGAIN on BSD)
		/// - `not-in-progress`:           A `connect` operation is not in progress.
		/// - `would-block`:               Can't finish the operation, it is still in progress. (EWOULDBLOCK, EAGAIN)
		///
		/// # References
		/// - <https://pubs.opengroup.org/onlinepubs/9699919799/functions/connect.html>
		/// - <https://man7.org/linux/man-pages/man2/connect.2.html>
		/// - <https://learn.microsoft.com/en-us/windows/win32/api/winsock2/nf-winsock2-connect>
		/// - <https://man.freebsd.org/cgi/man.cgi?connect>
		start-connect: func(network: borrow<network>, remote-address: ip-socket-address) -> result<_, error-code>;
		finish-connect: func() -> result<tuple<input-stream, output-stream>, error-code>;

		/// Start listening for new connections.
		///
		/// Transitions the socket into the Listener state.
		///
		/// Unlike POSIX:
		/// - this function is async. This enables interactive WASI hosts to inject permission prompts.
		/// - the socket must already be explicitly bound.
		///
		/// # Typical `start` errors
		/// - `invalid-state`:             The socket is not bound to any local address. (EDESTADDRREQ)
		/// - `invalid-state`:             The socket is already in the Connection state. (EISCONN, EINVAL on BSD)
		/// - `invalid-state`:             The socket is already in the Listener state.
		///
		/// # Typical `finish` errors
		/// - `address-in-use`:            Tried to perform an implicit bind, but there were no ephemeral ports available. (EADDRINUSE)
		/// - `not-in-progress`:           A `listen` operation is not in progress.
		/// - `would-block`:               Can't finish the operation, it is still in progress. (EWOULDBLOCK, EAGAIN)
		///
		/// # References
		/// - <https://pubs.opengroup.org/onlinepubs/9699919799/functions/listen.html>
		/// - <https://man7.org/linux/man-pages/man2/listen.2.html>
		/// - <https://learn.microsoft.com/en-us/windows/win32/api/winsock2/nf-winsock2-listen>
		/// - <https://man.freebsd.org/cgi/man.cgi?query=listen&sektion=2>
		start-listen: func() -> result<_, error-code>;
		finish-listen: func() -> result<_, error-code>;

		/// Accept a new client socket.
		///
		/// The returned socket is bound and in the Connection state. The following properties are inherited from the listener socket:
		/// - `address-family`
		/// - `ipv6-only`
		/// - `keep-alive`
		/// - `no-delay`
		/// - `unicast-hop-limit`
		/// - `receive-buffer-size`
		/// - `send-buffer-size`
		///
		/// On success, this function returns the newly accepted client socket along with
		/// a pair of streams that can be used to read & write to the connection.
		///
		/// # Typical errors
		/// - `invalid-state`:      Socket is not in the Listener state. (EINVAL)
		/// - `would-block`:        No pending connections at the moment. (EWOULDBLOCK, EAGAIN)
		/// - `connection-aborted`: An incoming connection was pending, but was terminated by the client before this listener could accept it. (ECONNABORTED)
		/// - `new-socket-limit`:   The new socket resource could not be created because of a system limit. (EMFILE, ENFILE)
		///
		/// # References
		/// - <https://pubs.opengroup.org/onlinepubs/9699919799/functions/accept.html>
		/// - <https://man7.org/linux/man-pages/man2/accept.2.html>
		/// - <https://learn.microsoft.com/en-us/windows/win32/api/winsock2/nf-winsock2-accept>
		/// - <https://man.freebsd.org/cgi/man.cgi?query=accept&sektion=2>
		accept: func() -> result<tuple<tcp-socket, input-stream, output-stream>, error-code>;

		/// Get the bound local address.
		///
		/// POSIX mentions:
		/// > If the socket has not been bound to a local name, the value
		/// > stored in the object pointed to by `address` is unspecified.
		///
		/// WASI is stricter and requires `local-address` to return `invalid-state` when the socket hasn't been bound yet.
		///
		/// # Typical errors
		/// - `invalid-state`: The socket is not bound to any local address.
		///
		/// # References
		/// - <https://pubs.opengroup.org/onlinepubs/9699919799/functions/getsockname.html>
		/// - <https://man7.org/linux/man-pages/man2/getsockname.2.html>
		/// - <https://learn.microsoft.com/en-us/windows/win32/api/winsock/nf-winsock-getsockname>
		/// - <https://man.freebsd.org/cgi/man.cgi?getsockname>
		local-address: func() -> result<ip-socket-address, error-code>;

		/// Get the remote address.
		///
		/// # Typical errors
		/// - `invalid-state`: The socket is not connected to a remote address. (ENOTCONN)
		///
		/// # References
		/// - <https://pubs.opengroup.org/onlinepubs/9699919799/functions/getpeername.html>
		/// - <https://man7.org/linux/man-pages/man2/getpeername.2.html>
		/// - <https://learn.microsoft.com/en-us/windows/win32/api/winsock/nf-winsock-getpeername>
		/// - <https://man.freebsd.org/cgi/man.cgi?query=getpeername&sektion=2&n=1>
		remote-address: func() -> result<ip-socket-address, error-code>;

		/// Whether this is a IPv4 or IPv6 socket.
		///
		/// Equivalent to the SO_DOMAIN socket option.
		address-family: func() -> ip-address-family;

		/// Whether IPv4 compatibility (dual-stack) mode is disabled or not.
		///
		/// Equivalent to the IPV6_V6ONLY socket option.
		///
		/// # Typical errors
		/// - `invalid-state`:        (set) The socket is already bound.
		/// - `not-supported`:        (get/set) `this` socket is an IPv4 socket.
		/// - `not-supported`:        (set) Host does not support dual-stack sockets. (Implementations are not required to.)
		ipv6-only: func() -> result<bool, error-code>;
		set-ipv6-only: func(value: bool) -> result<_, error-code>;

		/// Hints the desired listen queue size. Implementations are free to ignore this.
		///
		/// # Typical errors
		/// - `not-supported`:        (set) The platform does not support changing the backlog size after the initial listen.
		/// - `invalid-state`:        (set) The socket is already in the Connection state.
		set-listen-backlog-size: func(value: u64) -> result<_, error-code>;

		/// Equivalent to the SO_KEEPALIVE socket option.
		keep-alive: func() -> result<bool, error-code>;
		set-keep-alive: func(value: bool) -> result<_, error-code>;

		/// Equivalent to the TCP_NODELAY socket option.
		///
		/// The default value is `false`.
		no-delay: func() -> result<bool, error-code>;
		set-no-delay: func(value: bool) -> result<_, error-code>;

		/// Equivalent to the IP_TTL & IPV6_UNICAST_HOPS socket options.
		///
		/// # Typical errors
		/// - `invalid-argument`:     (set) The TTL value must be 1 or higher.
		/// - `invalid-state`:        (set) The socket is already in the Connection state.
		/// - `invalid-state`:        (set) The socket is already in the Listener state.
		unicast-hop-limit: func() -> result<u8, error-code>;
		set-unicast-hop-limit: func(value: u8) -> result<_, error-code>;

		/// The kernel buffer space reserved for sends/receives on this socket.
		///
		/// Note #1: an implementation may choose to cap or round the buffer size when setting the value.
		/// 	In other words, after setting a value, reading the same setting back may return a different value.
		///
		/// Note #2: there is not necessarily a direct relationship between the kernel buffer size and the bytes of
		/// 	actual data to be sent/received by the application, because the kernel might also use the buffer space
		/// 	for internal metadata structures.
		///
		/// Equivalent to the SO_RCVBUF and SO_SNDBUF socket options.
		///
		/// # Typical errors
		/// - `invalid-state`:        (set) The socket is already in the Connection state.
		/// - `invalid-state`:        (set) The socket is already in the Listener state.
		receive-buffer-size: func() -> result<u64, error-code>;
		set-receive-buffer-size: func(value: u64) -> result<_, error-code>;
		send-buffer-size: func() -> result<u64, error-code>;
		set-send-buffer-size: func(value: u64) -> result<_, error-code>;

		/// Create a `pollable` which will resolve once the socket is ready for I/O.
		///
		/// Note: this function is here for WASI Preview2 only.
		/// It's planned to be removed when `future` is natively supported in Preview3.
		subscribe: func() -> pollable;

		/// Initiate a graceful shutdown.
		///
		/// - receive: the socket is not expecting to receive any more data from the peer. All subsequent read
		///   operations on the `input-stream` associated with this socket will return an End Of Stream indication.
		///   Any data still in the receive queue at time of calling `shutdown` will be discarded.
		/// - send: the socket is not expecting to send any more data to the peer. All subsequent write
		///   operations on the `output-stream` associated with this socket will return an error.
		/// - both: same effect as receive & send combined.
		///
		/// The shutdown function does not close (drop) the socket.
		///
		/// # Typical errors
		/// - `invalid-state`: The socket is not in the Connection state. (ENOTCONN)
		///
		/// # References
		/// - <https://pubs.opengroup.org/onlinepubs/9699919799/functions/shutdown.html>
		/// - <https://man7.org/linux/man-pages/man2/shutdown.2.html>
		/// - <https://learn.microsoft.com/en-us/windows/win32/api/winsock/nf-winsock-shutdown>
		/// - <https://man.freebsd.org/cgi/man.cgi?query=shutdown&sektion=2>
		shutdown: func(shutdown-type: shutdown-type) -> result<_, error-code>;
	}
}