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Diffstat (limited to 'lib/libc/sys/listen.2')
-rw-r--r-- | lib/libc/sys/listen.2 | 120 |
1 files changed, 120 insertions, 0 deletions
diff --git a/lib/libc/sys/listen.2 b/lib/libc/sys/listen.2 new file mode 100644 index 0000000..eaa9522 --- /dev/null +++ b/lib/libc/sys/listen.2 @@ -0,0 +1,120 @@ +.\" 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. +.\" +.\" From: @(#)listen.2 8.2 (Berkeley) 12/11/93 +.\" $Id$ +.\" +.Dd November 3, 1995 +.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. +.Pp +The +.Xr sysctl 3 +MIB variable +.Dq Li kern.somaxconn +specifies a hard limit on +.Fa backlog ; +if a value greater than +.Li kern.somaxconn +or less than zero is specified, +.Fa backlog +is silently forced to +.Li kern.somaxconn . +.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 sysctl 1 , +.Xr accept 2 , +.Xr connect 2 , +.Xr socket 2 , +.Xr sysctl 3 +.Sh HISTORY +The +.Nm +function call appeared in +.Bx 4.2 . +The ability to configure the maximum +.Fa backlog +at run-time, and to use a negative +.Fa backlog +to request the maximum allowable value, was introduced in +.Tn FreeBSD +2.2. |