[apple/xnu.git] / bsd / man / man2 / listen.2

.\"	$OpenBSD: listen.2,v 1.2 1996/03/19 23:15:16 niklas Exp $
.\"	$NetBSD: listen.2,v 1.7 1996/02/16 20:38:45 phil Exp $
.\"
.\" Copyright (c) 1983, 1991, 1993
.\"	The Regents of the University of California.  All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\" 3. All advertising materials mentioning features or use of this software
.\"    must display the following acknowledgement:
.\"	This product includes software developed by the University of
.\"	California, Berkeley and its contributors.
.\" 4. Neither the name of the University nor the names of its contributors
.\"    may be used to endorse or promote products derived from this software
.\"    without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\"     @(#)listen.2	8.2 (Berkeley) 12/11/93
.\"
.Dd December 11, 1993
.Dt LISTEN 2
.Os BSD 4.2
.Sh NAME
.Nm listen
.Nd listen for connections on a socket
.Sh SYNOPSIS
.Fd #include <sys/socket.h>
.Ft int
.Fn listen "int s" "int backlog"
.Sh DESCRIPTION
To accept connections, a socket
is first created with
.Xr socket 2 ,
a willingness to accept incoming connections and
a queue limit for incoming connections are specified with
.Fn listen ,
and then the connections are
accepted with
.Xr accept 2 .
The
.Fn listen
call applies only to sockets of type
.Dv SOCK_STREAM
or
.Dv SOCK_SEQPACKET.
.Pp
The
.Fa backlog
parameter defines the maximum length the queue of
pending connections may grow to.
If a connection
request arrives with the queue full the client may
receive an error with an indication of
.Er ECONNREFUSED ,
or, if the underlying protocol supports retransmission,
the request may be ignored so that retries may succeed.
.Sh RETURN VALUES
A 0 return value indicates success; -1 indicates an error.
.Sh ERRORS
.Fn Listen
will fail if:
.Bl -tag -width Er
.It Bq Er EBADF
The argument
.Fa s
is not a valid descriptor.
.It Bq Er ENOTSOCK
The argument
.Fa s
is not a socket.
.It Bq Er EOPNOTSUPP
The socket is not of a type that supports the operation
.Fn listen .
.El
.Sh SEE ALSO
.Xr accept 2 ,
.Xr connect 2 ,
.Xr socket 2
.Sh BUGS
The
.Fa backlog
is currently limited (silently) to 128.
.Sh HISTORY
The
.Fn listen
function call appeared in
.Bx 4.2 .
Commit	Line	Data
9bccf70c A	1	.\" $OpenBSD: listen.2,v 1.2 1996/03/19 23:15:16 niklas Exp $
	2	.\" $NetBSD: listen.2,v 1.7 1996/02/16 20:38:45 phil Exp $
	3	.\"
	4	.\" Copyright (c) 1983, 1991, 1993
	5	.\" The Regents of the University of California. All rights reserved.
	6	.\"
	7	.\" Redistribution and use in source and binary forms, with or without
	8	.\" modification, are permitted provided that the following conditions
	9	.\" are met:
	10	.\" 1. Redistributions of source code must retain the above copyright
	11	.\" notice, this list of conditions and the following disclaimer.
	12	.\" 2. Redistributions in binary form must reproduce the above copyright
	13	.\" notice, this list of conditions and the following disclaimer in the
	14	.\" documentation and/or other materials provided with the distribution.
	15	.\" 3. All advertising materials mentioning features or use of this software
	16	.\" must display the following acknowledgement:
	17	.\" This product includes software developed by the University of
	18	.\" California, Berkeley and its contributors.
	19	.\" 4. Neither the name of the University nor the names of its contributors
	20	.\" may be used to endorse or promote products derived from this software
	21	.\" without specific prior written permission.
	22	.\"
	23	.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
	24	.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	25	.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	26	.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
	27	.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	28	.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	29	.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	30	.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	31	.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	32	.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	33	.\" SUCH DAMAGE.
	34	.\"
	35	.\" @(#)listen.2 8.2 (Berkeley) 12/11/93
	36	.\"
	37	.Dd December 11, 1993
	38	.Dt LISTEN 2
	39	.Os BSD 4.2
	40	.Sh NAME
	41	.Nm listen
	42	.Nd listen for connections on a socket
	43	.Sh SYNOPSIS
	44	.Fd #include <sys/socket.h>
	45	.Ft int
	46	.Fn listen "int s" "int backlog"
	47	.Sh DESCRIPTION
	48	To accept connections, a socket
	49	is first created with
	50	.Xr socket 2 ,
	51	a willingness to accept incoming connections and
	52	a queue limit for incoming connections are specified with
	53	.Fn listen ,
	54	and then the connections are
	55	accepted with
	56	.Xr accept 2 .
	57	The
	58	.Fn listen
	59	call applies only to sockets of type
	60	.Dv SOCK_STREAM
	61	or
	62	.Dv SOCK_SEQPACKET.
	63	.Pp
	64	The
65	.Fa backlog
66	parameter defines the maximum length the queue of
67	pending connections may grow to.
68	If a connection
69	request arrives with the queue full the client may
70	receive an error with an indication of
71	.Er ECONNREFUSED ,
72	or, if the underlying protocol supports retransmission,
73	the request may be ignored so that retries may succeed.
74	.Sh RETURN VALUES
75	A 0 return value indicates success; -1 indicates an error.
76	.Sh ERRORS
77	.Fn Listen
78	will fail if:
79	.Bl -tag -width Er
80	.It Bq Er EBADF
81	The argument
82	.Fa s
83	is not a valid descriptor.
84	.It Bq Er ENOTSOCK
85	The argument
86	.Fa s
87	is not a socket.
88	.It Bq Er EOPNOTSUPP
89	The socket is not of a type that supports the operation
90	.Fn listen .
91	.El
92	.Sh SEE ALSO
93	.Xr accept 2 ,
94	.Xr connect 2 ,
95	.Xr socket 2
96	.Sh BUGS
97	The
98	.Fa backlog
99	is currently limited (silently) to 128.
100	.Sh HISTORY
101	The
102	.Fn listen
103	function call appeared in
104	.Bx 4.2 .