.\" Copyright (c) 2007 Bruce M. Simpson.
.\" 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.
.\" 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.
.\"
.\"     @(#)shutdown.2	8.1 (Berkeley) 6/4/93
.\" $FreeBSD: src/lib/libc/sys/shutdown.2,v 1.22.10.1.6.1 2010/12/21 17:09:25 kensmith Exp $
.\"
.Dd March 5, 2007
.Dt SHUTDOWN 2
.Os
.Sh NAME
.Nm shutdown
.Nd disable sends and/or receives on a socket
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In sys/types.h
.In sys/socket.h
.Ft int
.Fn shutdown "int s" "int how"
.Sh DESCRIPTION
The
.Fn shutdown
system call disables sends or receives on a socket.
The
.Fa how
argument specifies the type of shutdown.
Possible values are:
.Bl -tag -width ".Dv SHUT_RDWR"
.It Dv SHUT_RD
Further receives will be disallowed.
.It Dv SHUT_WR
Further sends will be disallowed.
This may cause actions specific to the protocol family of the socket
.Fa s
to happen; see
.Sx IMPLEMENTATION NOTES .
.It Dv SHUT_RDWR
Further sends and receives will be disallowed.
Implies
.Dv SHUT_WR .
.El
.Pp
If the file descriptor
.Fa s
is associated with a
.Dv SOCK_STREAM
socket, all or part of the full-duplex connection will be shut down.
.\"
.Sh IMPLEMENTATION NOTES
The following protocol specific actions apply to the use of
.Dv SHUT_WR
(and potentially also
.Dv SHUT_RDWR ) ,
based on the properties of the socket associated with the file descriptor
.Fa s .
.Bl -column ".Dv PF_INET6" ".Dv SOCK_STREAM" ".Dv IPPROTO_SCTP"
.It Sy Domain Ta Sy Type Ta Sy Protocol Ta Sy Return value and action
.It Dv PF_INET Ta Dv SOCK_DGRAM Ta Dv IPPROTO_SCTP Ta
Return \-1.
The global variable
.Va errno
will be set to
.Er EOPNOTSUPP .
.It Dv PF_INET Ta Dv SOCK_DGRAM Ta Dv IPPROTO_UDP Ta
Return 0.
ICMP messages will
.Em not
be generated.
.It Dv PF_INET Ta Dv SOCK_STREAM Ta Dv IPPROTO_SCTP Ta
Return 0.
Send queued data and tear down association.
.It Dv PF_INET Ta Dv SOCK_STREAM Ta Dv IPPROTO_TCP Ta
Return 0.
Send queued data, wait for ACK, then send FIN.
.It Dv PF_INET6 Ta Dv SOCK_DGRAM Ta Dv IPPROTO_SCTP Ta
Return \-1.
The global variable
.Va errno
will be set to
.Er EOPNOTSUPP .
.It Dv PF_INET6 Ta Dv SOCK_DGRAM Ta Dv IPPROTO_UDP Ta
Return 0.
ICMP messages will
.Em not
be generated.
.It Dv PF_INET6 Ta Dv SOCK_STREAM Ta Dv IPPROTO_SCTP Ta
Return 0.
Send queued data and tear down association.
.It Dv PF_INET6 Ta Dv SOCK_STREAM Ta Dv IPPROTO_TCP Ta
Return 0.
Send queued data, wait for ACK, then send FIN.
.El
.\"
.Sh RETURN VALUES
.Rv -std shutdown
.Sh ERRORS
The
.Fn shutdown
system call fails if:
.Bl -tag -width Er
.It Bq Er EBADF
The
.Fa s
argument is not a valid file descriptor.
.It Bq Er EINVAL
The
.Fa how
argument is invalid.
.It Bq Er EOPNOTSUPP
The socket associated with the file descriptor
.Fa s
does not support this operation.
.It Bq Er ENOTCONN
The
.Fa s
argument specifies a
.Dv SOCK_STREAM
socket which is not connected.
.It Bq Er ENOTSOCK
The
.Fa s
argument does not refer to a socket.
.El
.Sh SEE ALSO
.Xr connect 2 ,
.Xr socket 2 ,
.Xr inet 4 ,
.Xr inet6 4
.Sh STANDARDS
The
.Fn shutdown
system call is expected to comply with
.St -p1003.1g-2000 ,
when finalized.
.Sh HISTORY
The
.Fn shutdown
system call appeared in
.Bx 4.2 .
The
.Dv SHUT_RD , SHUT_WR ,
and
.Dv SHUT_RDWR
constants appeared in
.St -p1003.1g-2000 .
.Sh AUTHORS
.An -nosplit
This manual page was updated by
.An Bruce M. Simpson Aq bms@FreeBSD.org
to reflect how
.Fn shutdown
behaves with
.Dv PF_INET
and
.Dv PF_INET6
sockets.
.Sh BUGS
The ICMP
.Dq Li "port unreachable"
message should be generated in response to
datagrams received on a local port to which
.Fa s
is bound
after
.Fn shutdown
is called.