address-family---The address/protocol family of this socket. Currently only :internet (the default), meaning IP, and :file, referring to UNIX domain addresses, are supported.

type---One of :stream (the default) to request a connection-oriented socket, or :datagram to request a connectionless socket. The default is :stream.

connect---This argument is only relevant to sockets of type :stream. One of :active (the default) to request a :passive to request a file or TCP listener socket.

eol---This argument is currently ignored (it is accepted for compatibility with Franz Allegro).

format---One of :text (the default), :binary, or :bivalent. This argument is ignored for :stream sockets for now, as :stream sockets are currently always bivalent (i.e. they support both character and byte I/O). For :datagram sockets, this argument is ignored (the format of a datagram socket is always :binary).

remote-host---Required for TCP streams, it specifies the host to connect to (in any format acceptable to lookup-hostname). Ignored for listener sockets. For UDP sockets, it can be used to specify a default host for subsequent calls to send-to or receive-from.

remote-port---Required for TCP streams, it specifies the port to connect to (in any format acceptable to lookup-port). Ignored for listener sockets. For UDP sockets, it can be used to specify a default port for subsequent calls to for subsequent calls to send-to or receive-from.

remote-filename---Required for file-socket streams, it specifies the name of a file in the local filesystem (e.g., NOT mounted via NFS, AFP, SMB, ...) which names and controls access to a UNIX-domain socket.

local-host---Allows you to specify a local host address for a listener or UDP socket, for the rare case where you want to restrict connections to those coming to a specific local address for security reasons.

local-port---Specify a local port for a socket. Most useful for listener sockets, where it is the port on which the socket will listen for connections.

local-filename---Required for file-listener-sockets. Specifies the name of a file in the local filesystem which is used to name a UNIX-domain socket. The actual filesystem file should not previously exist when the file-listener-socket is created; its parent directory should exist and be writable by the caller. The file used to name the socket will be deleted when the file-listener-socket is closed.

keepalive---If true, enables the periodic transmission of "keepalive" messages.

reuse-address---If true, allows the reuse of local ports in listener sockets, overriding some TCP/IP protocol specifications. You will need this if you are debugging a server..

nodelay---If true, disables Nagle's algorithm, which tries to minimize TCP packet fragmentation by introducing transmission delays in the absence of replies. Try setting this if you are using a protocol which involves sending a steady stream of data with no replies and are seeing significant degradations in throughput.

broadcast---If true, requests permission to broadcast datagrams on a UDP socket.

linger---If specified and non-nil, should be the number of seconds the OS is allowed to wait for data to be pushed through when a close is done. Only relevant for TCP sockets.

backlog---For a listener socket, specifies the number of connections which can be pending but not accepted. The default is 5, which is also the maximum on some operating systems.

input-timeout---The number of seconds before an input operation times out. Must be a real number between zero and one million. If an input operation takes longer than the specified number of seconds, an input-timeout error is signalled. (see Section 10.1.4, “Stream Timeouts and Deadlines”)

output-timeout---The number of seconds before an output operation times out. Must be a real number between zero and one million. If an output operation takes longer than the specified number of seconds, an output-timeout error is signalled. (see Section 10.1.4, “Stream Timeouts and Deadlines”)

connect-timeout---The number of seconds before a connection attempt times out. [TODO: what are acceptable values?] If a connection attempt takes longer than the specified number of seconds, a socket-error is signalled. This can be useful if the specified interval is shorter than the interval that the OS's socket layer imposes, which is sometimes a minute or two.

auto-close---When non-nil, any resulting socket stream will be closed when the GC can prove that the stream is unreferenced. This is done via CCL's termination mechanism [TODO add xref].

deadline---Specifies an absolute time in internal-time-units. If an I/O operation on the stream does not complete before the deadline then a COMMUNICATION-DEADLINE-EXPIRED error is signalled. A deadline takes precedence over any input/output timeouts that may be set. (see Section 10.1.4, “Stream Timeouts and Deadlines”)

Creates and returns a new socket

socket---The listener-socket to listen on.

wait---If true (the default), and there are no connections waiting to be accepted, waits until one arrives. If false, returns NIL immediately.

Extracts the first connection on the queue of pending connections, accepts it (i.e. completes the connection startup protocol) and returns a new tcp-stream or file-socket-stream representing the newly established connection. The tcp stream inherits any properties of the listener socket that are relevant (e.g. :keepalive, :nodelay, etc.) The original listener socket continues to be open listening for more connections, so you can call accept-connection on it again.

dotted---A string representing an IP address in the "nn.nn.nn.nn" format

errorp---If true (the default) an error is signaled if dotted is invalid. If false, NIL is returned.

Converts a dotted-string representation of a host address to a 32-bit unsigned IP address.

ipaddr---A 32-bit integer representing an internet host address

values---If false (the default), returns a string in the form "nn.nn.nn.nn". If true, returns four values representing the four octets of the address as unsigned 8-bit integers.

Converts a 32-bit unsigned IP address into octets.

ipaddr---a 32-bit integer representing an internet host address

ignore-cache---This argument is ignored (it is accepted for compatibility with Franz Allegro)

Converts a 32-bit unsigned IP address into a host name string

host---Specifies the host. It can be either a host name string such as "clozure.com", or a dotted address string such as "192.168.0.1", or a 32-bit unsigned IP address such as 3232235521.

Converts a host spec in any of the acceptable formats into a 32-bit unsigned IP address

port---Specifies the port. It can be either a string, such as "http" or a symbol, such as :http, or an unsigned port number. Note that a string is case-sensitive. A symbol is lowercased before lookup.

protocol---Must be one of "tcp" or "udp".

Finds the port number for the specified port and protocol

socket---The socket to read from

size---Maximum number of bytes to read. If the packet is larger than this, any extra bytes are discarded.

buffer---If specified, must be an octet vector which will be used to read in the data. If not specified, a new buffer will be created (of type determined by socket-format).

extract---If true, the subsequence of the buffer corresponding only to the data read in is extracted and returned as the first value. If false (the default) the original buffer is returned even if it is only partially filled.

offset---Specifies the start offset into the buffer at which data is to be stored. The default is 0.

Reads a UDP packet from a socket. If no packets are available, waits for a packet to arrive. Returns four values:

socket---The socket to write to

buffer---A vector containing the data to send. It must be an octet vector.

size---Number of octets to send

remote-host---The host to send the packet to, in any format acceptable to lookup-hostname. The default is the remote host specified in the call to make-socket.

remote-port---The port to send the packet to, in any format acceptable to lookup-port. The default is the remote port specified in the call to make-socket.

offset---The offset in the buffer where the packet data starts

Send a UDP packet over a socket.

socket---The socket to shut down (typically a tcp-stream)

direction---One of :input to disallow further input, or :output to disallow further output.

Shuts down part of a bidirectional connection. This is useful if e.g. you need to read responses after sending an end-of-file signal.

socket---The socket

Returns the native OS's representation of the socket, or NIL if the socket is closed. On Unix, this is the Unix 'file descriptor', a small non-negative integer. Note that it is rather dangerous to mess around with tcp-stream fd's, as there is all sorts of buffering and asynchronous I/O going on above the OS level. listener-socket and udp-socket fd's are safer to mess with directly as there is less magic going on.

socket---The socket

Returns the 32-bit unsigned IP address of the remote host, or NIL if the socket is not connected.

socket---The socket

Returns the remote port number, or NIL if the socket is not connected.

socket---The socket

Returns 32-bit unsigned IP address of the local host.

socket---The socket

Returns the local port number

socket---The socket

Returns :internet or :file, as appropriate.

socket---The socket

Returns :active for tcp-stream, :passive for listener-socket, and NIL for udp-socket

socket---The socket

Returns the socket format as specified by the :format argument to make-socket.

socket---The socket

returns :stream for tcp-stream and listener-socket, and :datagram for udp-socket.

The class of OS errors signaled by socket functions

simple-error

socket-error---the condition

The OS error code of the error

socket-error---the condition

A symbol representing the error code in a more OS-independent way.

One of: :address-in-use :connection-aborted :no-buffer-space :connection-timed-out :connection-refused :host-unreachable :host-down :network-down :address-not-available :network-reset :connection-reset :shutdown :access-denied or :unknown.

socket-error---the condition

A string describing the context where the error happened. On Linux, this is the name of the system call which returned the error.

socket---The socket to close

abort---If false (the default), closes the socket in an orderly fashion, finishing up any buffered pending I/O, before closing the connection. If true, aborts/ignores pending I/O. (For listener and udp sockets, this argument is effectively ignored since there is never any buffered I/O to clean up).

The close generic function can be applied to sockets. It releases the operating system resources associated with the socket.

var---variable to bind

make-socket-args---arguments suitable for passing to make-socket

body---body to execute

executes body with var bound to the result of applying make-socket to make-socket-args. The socket gets closed on exit.