SHUTDOWN(2) MidnightBSD System Calls Manual SHUTDOWN(2)

NAME

shutdown — disable sends and/or receives on a socket

LIBRARY

Standard C Library (libc, −lc)

SYNOPSIS

#include <sys/types.h>
#include <sys/socket.h>

int

shutdown(int s, int how);

DESCRIPTION

The shutdown() system call disables sends or receives on a socket. The how argument specifies the type of shutdown. Possible values are:

SHUT_RD

Further receives will be disallowed.

SHUT_WR

Further sends will be disallowed. This may cause actions specific to the protocol family of the socket s to happen; see IMPLEMENTATION NOTES.

SHUT_RDWR

Further sends and receives will be disallowed. Implies SHUT_WR.

If the file descriptor s is associated with a SOCK_STREAM socket, all or part of the full-duplex connection will be shut down.

IMPLEMENTATION NOTES

The following protocol specific actions apply to the use of SHUT_WR (and potentially also SHUT_RDWR), based on the properties of the socket associated with the file descriptor s.

Domain Type Protocol Return value and action
PF_INET SOCK_DGRAM IPPROTO_SCTP Return −1. The global variable errno will be set to EOPNOTSUPP.
PF_INET SOCK_DGRAM IPPROTO_UDP Return 0. ICMP messages will not be generated.
PF_INET SOCK_STREAM IPPROTO_SCTP Return 0. Send queued data and tear down association.
PF_INET SOCK_STREAM IPPROTO_TCP Return 0. Send queued data, wait for ACK, then send FIN.
PF_INET6 SOCK_DGRAM IPPROTO_SCTP Return −1. The global variable errno will be set to EOPNOTSUPP.
PF_INET6 SOCK_DGRAM IPPROTO_UDP Return 0. ICMP messages will not be generated.
PF_INET6 SOCK_STREAM IPPROTO_SCTP Return 0. Send queued data and tear down association.
PF_INET6 SOCK_STREAM IPPROTO_TCP Return 0. Send queued data, wait for ACK, then send FIN.

RETURN VALUES

The shutdown() function returns the value 0 if successful; otherwise the value −1 is returned and the global variable errno is set to indicate the error.

ERRORS

The shutdown() system call fails if:

[EBADF]

The s argument is not a valid file descriptor.

[EINVAL]

The how argument is invalid.

[EOPNOTSUPP]

The socket associated with the file descriptor s does not support this operation.

[ENOTCONN]

The s argument specifies a SOCK_STREAM socket which is not connected.

[ENOTSOCK]

The s argument does not refer to a socket.

SEE ALSO

connect(2), socket(2), inet(4), inet6(4)

STANDARDS

The shutdown() system call is expected to comply with IEEE Std 1003.1g-2000 (‘‘POSIX.1’’), when finalized.

HISTORY

The shutdown() system call appeared in 4.2BSD. The SHUT_RD, SHUT_WR, and SHUT_RDWR constants appeared in IEEE Std 1003.1g-2000 (‘‘POSIX.1’’).

AUTHORS

This manual page was updated by Bruce M. Simpson 〈bms@FreeBSD.org〉 to reflect how shutdown() behaves with PF_INET and PF_INET6 sockets.

BUGS

The ICMP ‘‘port unreachable’’ message should be generated in response to datagrams received on a local port to which s is bound after shutdown() is called.

MidnightBSD 0.3 March 5, 2007 MidnightBSD 0.3