accept()

Description

Accept a connection on a socket.

#include <winsock.h>

SOCKET PASCAL FAR accept ( SOCKET s, struct sockaddr FAR * addr, int FAR * addrlen);

s

A descriptor identifying a socket which is listening for connections after a listen().
addr
An optional pointer to a buffer which receives the address of the connecting entity, as known to the communications layer. The exact format of the addr argument is determined by the address family established when the socket was created.
addrlen
A optional pointer to an integer which contains the length of the address addr.

Remarks

This routine extracts the first connection on the queue of pending connections on s, creates a new socket with the same properties as s and returns a handle to the new socket. If no pending connections are present on the queue, and the socket is not marked as non-blocking, accept() blocks the caller until a connection is present. If the socket is marked non-blocking and no pending connections are present on the queue, accept() returns an error as described below. The accepted socket may not be used to accept more connections. The original socket remains open.

The argument addr is a result parameter that is filled in with the address of the connecting entity, as known to the communications layer. The exact format of the addr parameter is determined by the address family in which the communication is occurring. The addrlen is a value-result parameter; it should initially contain the amount of space pointed to by addr; on return it will contain the actual length (in bytes) of the address returned. This call is used with connection-based socket types such as SOCK_STREAM. If addr and/or addrlen are equal to NULL, then no information about the remote address of the accepted socket is returned.

Return Value

If no error occurs, accept() returns a value of type SOCKET which is a descriptor for the accepted packet. Otherwise, a value of INVALID_SOCKET is returned, and a specific error code may be retrieved by calling WSAGetLastError().

The integer referred to by addrlen initially contains the amount of space pointed to by addr. On return it will contain the actual length in bytes of the address returned.

Error Codes

WSANOTINITIALISED

A successful WSAStartup() must occur before using this API.
WSAENETDOWN
The Windows Sockets implementation has detected that the network subsystem has failed.
WSAEFAULT
The addrlen argument is too small (less than the sizeof a struct sockaddr).
WSAEINTR
The (blocking) call was canceled via WSACancelBlockingCall()
WSAEINPROGRESS
A blocking Windows Sockets call is in progress.
WSAEINVAL
listen() was not invoked prior to accept().
WSAEMFILE
The queue is empty upon entry to accept() and there are no descriptors available.
WSAENOBUFS
No buffer space is available.
WSAENOTSOCK
The descriptor is not a socket.
WSAEOPNOTSUPP
The referenced socket is not a type that supports connection-oriented service.
WSAEWOULDBLOCK
The socket is marked as non-blocking and no connections are present to be accepted.

See Also

bind(), connect(), listen(), select(), socket(), WSAAsyncSelect()

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