The default values for options given to connect can be affected by the Kernel configuration parameter inet_default_connect_options. See inet(3) for details.

listen(Port, Options) -> {ok, ListenSocket} | {error, Reason}

Types

Port = 0..65535

Options = [Opt]

 Opt -- see below

ListenSocket -- see below

Reason = posix()

Sets up a socket to listen on the port Port on the local host.

If Port == 0, the underlying OS assigns an available port number, use inet:port/1 to retrieve it.

The available options are:

list: Received Packet is delivered as a list.

binary: Received Packet is delivered as a binary.

{backlog, B}: B is an integer >= 0. The backlog value defaults to 5. The backlog value defines the maximum length that the queue of pending connections may grow to.

{ip, ip_address()}: If the host has several network interfaces, this option specifies which one to listen on.

{fd, Fd}: If a socket has somehow been connected without using gen_tcp, use this option to pass the file descriptor for it.

inet6: Set up the socket for IPv6.

inet: Set up the socket for IPv4.

Opt: See inet:setopts/2.

The returned socket ListenSocket can only be used in calls to accept/1, 2.

The default values for options given to listen can be affected by the Kernel configuration parameter inet_default_listen_options. See inet(3) for details.

accept(ListenSocket) -> {ok, Socket} | {error, Reason}

accept(ListenSocket, Timeout) -> {ok, Socket} | {error, Reason}

Types

ListenSocket -- see listen/2

Timeout = int() | infinity

Socket = socket()

Reason = closed | timeout | posix()

Accepts an incoming connection request on a listen socket. Socket must be a socket returned from listen/2. Timeout specifies a timeout value in ms, defaults to infinity.

Returns {ok, Socket} if a connection is established, or {error, closed} if ListenSocket is closed, or {error, timeout} if no connection is established within the specified time. May also return a POSIX error value if something else goes wrong, see inet(3) for possible error values.

Packets can be sent to the returned socket Socket using send/2. Packets sent from the peer are delivered as messages:

{tcp, Socket, Data}

unless {active, false} was specified in the option list for the listen socket, in which case packets are retrieved by calling recv/2.

send(Socket, Packet) -> ok | {error, Reason}

Types

Socket = socket()

Packet = [char()] | binary()

Reason = posix()

Sends a packet on a socket.

recv(Socket, Length) -> {ok, Packet} | {error, Reason}

recv(Socket, Length, Timeout) -> {ok, Packet} | {error, Reason}

Types

Socket = socket()

Length = int()

Packet = [char()] | binary()

Timeout = int() | infinity

Reason = closed | posix()

This function receives a packet from a socket in passive mode. A closed socket is indicated by a return value {error, closed}.

The Length argument is only meaningful when the socket is in raw mode and denotes the number of bytes to read. If Length = 0, all available bytes are returned. If Length > 0, exactly Length bytes are returned, or an error; possibly discarding less than Length bytes of data when the socket gets closed from the other side.

The optional Timeout parameter specifies a timeout in milliseconds. The default value is infinity.

controlling_process(Socket, Pid) -> ok | {error, eperm}

Types

Socket = socket()

Pid = pid()

Assigns a new controlling process Pid to Socket. The controlling process is the process which receives messages from the socket. If called by any other process than the current controlling process, {error, eperm} is returned.

close(Socket) -> ok | {error, Reason}

Types

Socket = socket()

Reason = posix()

Closes a TCP socket.

shutdown(Socket, How) -> ok | {error, Reason}

Types

Socket = socket()

How = read | write | read_write

Reason = posix()

Immediately close a socket in one or two directions.

How == write means closing the socket for writing, reading from it is still possible.

To be able to handle that the peer has done a shutdown on the write side, the {exit_on_close, false} option is useful.