shutdown

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Disable sends and/or receives on a socket.

#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 include:

`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.

A call to close(s) is not required after invoking shutdown(s,2) which is the same as shutdown(s, SHUT_RDWR), as all the resources associated with the socket are implicitly freed.

Remarks

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	Returns -1. The global variable errno will be set to EOPNOTSUPP.
	SOCK_DGRAM	IPPROTO_UDP	Returns 0. ICMP messages will not be generated.
	SOCK_STREAM	IPPROTO_SCTP	Returns 0. Send queued data and tear down association.
	SOCK_STREAM	IPPROTO_TCP	Returns 0. Send queued data, wait for ACK, then send FIN.
PF_INET6	SOCK_DGRAM	IPPROTO_SCTP	Returns -1. The global variable errno will be set to EOPNOTSUPP.
	SOCK_DGRAM	IPPROTO_UDP	Returns 0. ICMP messages will not be generated.
	SOCK_STREAM	IPPROTO_SCTP	Returns 0. Send queued data and tear down association.
	SOCK_STREAM	IPPROTO_TCP	Returns 0. Send queued data, wait for ACK, then send FIN.

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.

Return Values

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

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.

Requirements

Versions	Link to
INtime 4.0	netlib.lib

Description

Remarks

Bugs

Return Values

Requirements

See Also