1*64ebeb5cSwiz.\" $NetBSD: listen.2,v 1.16 2004/05/13 10:20:58 wiz Exp $ 24eab61bdScgd.\" 34eab61bdScgd.\" Copyright (c) 1983, 1991, 1993 44eab61bdScgd.\" The Regents of the University of California. All rights reserved. 561f28255Scgd.\" 661f28255Scgd.\" Redistribution and use in source and binary forms, with or without 761f28255Scgd.\" modification, are permitted provided that the following conditions 861f28255Scgd.\" are met: 961f28255Scgd.\" 1. Redistributions of source code must retain the above copyright 1061f28255Scgd.\" notice, this list of conditions and the following disclaimer. 1161f28255Scgd.\" 2. Redistributions in binary form must reproduce the above copyright 1261f28255Scgd.\" notice, this list of conditions and the following disclaimer in the 1361f28255Scgd.\" documentation and/or other materials provided with the distribution. 14eb7c1594Sagc.\" 3. Neither the name of the University nor the names of its contributors 1561f28255Scgd.\" may be used to endorse or promote products derived from this software 1661f28255Scgd.\" without specific prior written permission. 1761f28255Scgd.\" 1861f28255Scgd.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 1961f28255Scgd.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 2061f28255Scgd.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 2161f28255Scgd.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 2261f28255Scgd.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 2361f28255Scgd.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 2461f28255Scgd.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 2561f28255Scgd.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 2661f28255Scgd.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 2761f28255Scgd.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 2861f28255Scgd.\" SUCH DAMAGE. 2961f28255Scgd.\" 304eab61bdScgd.\" @(#)listen.2 8.2 (Berkeley) 12/11/93 3161f28255Scgd.\" 324eab61bdScgd.Dd December 11, 1993 3361f28255Scgd.Dt LISTEN 2 3438c96853Sgarbled.Os 3561f28255Scgd.Sh NAME 3661f28255Scgd.Nm listen 3761f28255Scgd.Nd listen for connections on a socket 3815be242bSkleink.Sh LIBRARY 3915be242bSkleink.Lb libc 4061f28255Scgd.Sh SYNOPSIS 41472351e1Swiz.In sys/socket.h 4261f28255Scgd.Ft int 4361f28255Scgd.Fn listen "int s" "int backlog" 4461f28255Scgd.Sh DESCRIPTION 4561f28255ScgdTo accept connections, a socket 4661f28255Scgdis first created with 4761f28255Scgd.Xr socket 2 , 4861f28255Scgda willingness to accept incoming connections and 4961f28255Scgda queue limit for incoming connections are specified with 5061f28255Scgd.Fn listen , 5161f28255Scgdand then the connections are 5261f28255Scgdaccepted with 5361f28255Scgd.Xr accept 2 . 5461f28255ScgdThe 5561f28255Scgd.Fn listen 5661f28255Scgdcall applies only to sockets of type 5761f28255Scgd.Dv SOCK_STREAM 5861f28255Scgdor 5961f28255Scgd.Dv SOCK_SEQPACKET . 6061f28255Scgd.Pp 6161f28255ScgdThe 6261f28255Scgd.Fa backlog 6361f28255Scgdparameter defines the maximum length the queue of 6461f28255Scgdpending connections may grow to. 6561f28255ScgdIf a connection 6661f28255Scgdrequest arrives with the queue full the client may 6761f28255Scgdreceive an error with an indication of 6861f28255Scgd.Er ECONNREFUSED , 6961f28255Scgdor, if the underlying protocol supports retransmission, 7061f28255Scgdthe request may be ignored so that retries may succeed. 7161f28255Scgd.Sh RETURN VALUES 72*64ebeb5cSwizA 0 return value indicates success; \-1 indicates an error. 7361f28255Scgd.Sh ERRORS 74ce83c69eSlukem.Fn listen 759c4ad8fbSjtcwill fail if: 76250b6aa0Sjtc.Bl -tag -width Er 7761f28255Scgd.It Bq Er EBADF 7861f28255ScgdThe argument 7961f28255Scgd.Fa s 8061f28255Scgdis not a valid descriptor. 8161f28255Scgd.It Bq Er ENOTSOCK 8261f28255ScgdThe argument 8361f28255Scgd.Fa s 8461f28255Scgdis not a socket. 8561f28255Scgd.It Bq Er EOPNOTSUPP 8661f28255ScgdThe socket is not of a type that supports the operation 8761f28255Scgd.Fn listen . 8861f28255Scgd.El 8961f28255Scgd.Sh SEE ALSO 9061f28255Scgd.Xr accept 2 , 9161f28255Scgd.Xr connect 2 , 9261f28255Scgd.Xr socket 2 9361f28255Scgd.Sh HISTORY 9461f28255ScgdThe 956e9ac180Sjtc.Fn listen 9661f28255Scgdfunction call appeared in 9761f28255Scgd.Bx 4.2 . 9853d84b5cSwiz.Sh BUGS 9953d84b5cSwizThe 10053d84b5cSwiz.Fa backlog 10153d84b5cSwizis currently limited (silently) to 128. 102