[unix-history] / usr / src / lib / libc / sys / listen.2

.\" Copyright (c) 1983, 1991 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	6.5 (Berkeley) 3/10/91
.\"
.Dd March 10, 1991
.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 [EOPNOTSUPP]
.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 5.
.Sh HISTORY
The
.Nm
function call appeared in
.Bx 4.2 .
Commit	Line	Data
55c2faba WJ	1	.\" Copyright (c) 1983, 1991 The Regents of the University of California.
	2	.\" All rights reserved.
	3	.\"
	4	.\" Redistribution and use in source and binary forms, with or without
	5	.\" modification, are permitted provided that the following conditions
	6	.\" are met:
	7	.\" 1. Redistributions of source code must retain the above copyright
	8	.\" notice, this list of conditions and the following disclaimer.
	9	.\" 2. Redistributions in binary form must reproduce the above copyright
	10	.\" notice, this list of conditions and the following disclaimer in the
	11	.\" documentation and/or other materials provided with the distribution.
	12	.\" 3. All advertising materials mentioning features or use of this software
	13	.\" must display the following acknowledgement:
	14	.\" This product includes software developed by the University of
	15	.\" California, Berkeley and its contributors.
	16	.\" 4. Neither the name of the University nor the names of its contributors
	17	.\" may be used to endorse or promote products derived from this software
	18	.\" without specific prior written permission.
	19	.\"
	20	.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
	21	.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	22	.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	23	.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
	24	.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	25	.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	26	.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	27	.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	28	.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	29	.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	30	.\" SUCH DAMAGE.
	31	.\"
	32	.\" @(#)listen.2 6.5 (Berkeley) 3/10/91
	33	.\"
	34	.Dd March 10, 1991
	35	.Dt LISTEN 2
	36	.Os BSD 4.2
	37	.Sh NAME
	38	.Nm listen
	39	.Nd listen for connections on a socket
	40	.Sh SYNOPSIS
	41	.Fd #include <sys/socket.h>
	42	.Ft int
	43	.Fn listen "int s" "int backlog"
	44	.Sh DESCRIPTION
	45	To accept connections, a socket
	46	is first created with
	47	.Xr socket 2 ,
	48	a willingness to accept incoming connections and
	49	a queue limit for incoming connections are specified with
	50	.Fn listen ,
	51	and then the connections are
	52	accepted with
	53	.Xr accept 2 .
	54	The
	55	.Fn listen
	56	call applies only to sockets of type
	57	.Dv SOCK_STREAM
	58	or
	59	.Dv SOCK_SEQPACKET.
	60	.Pp
	61	The
	62	.Fa backlog
	63	parameter defines the maximum length the queue of
	64	pending connections may grow to.
65	If a connection
66	request arrives with the queue full the client may
67	receive an error with an indication of
68	.Er ECONNREFUSED ,
69	or, if the underlying protocol supports retransmission,
70	the request may be ignored so that retries may succeed.
71	.Sh RETURN VALUES
72	A 0 return value indicates success; -1 indicates an error.
73	.Sh ERRORS
74	.Fn Listen will fail if:
75	.Bl -tag -width [EOPNOTSUPP]
76	.It Bq Er EBADF
77	The argument
78	.Fa s
79	is not a valid descriptor.
80	.It Bq Er ENOTSOCK
81	The argument
82	.Fa s
83	is not a socket.
84	.It Bq Er EOPNOTSUPP
85	The socket is not of a type that supports the operation
86	.Fn listen .
87	.El
88	.Sh SEE ALSO
89	.Xr accept 2 ,
90	.Xr connect 2 ,
91	.Xr socket 2
92	.Sh BUGS
93	The
94	.Fa backlog
95	is currently limited (silently) to 5.
96	.Sh HISTORY
97	The
98	.Nm
99	function call appeared in
100	.Bx 4.2 .