accept

The Windows Sockets accept function accepts an incoming connection attempt on a socket.

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

Parameters

s: [in] A descriptor identifying a socket that has been placed in a listening state with the listen function. The connection will actually be made with the socket that is returned by accept.
addr: [out] An optional pointer to a buffer that receives 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 established when the socket was created.
addrlen: [out] An optional pointer to an integer that contains the length of the address addr.

Remarks

The accept function extracts the first connection on the queue of pending connections on socket s. It then creates a new socket and returns a handle to the new socket. The newly created socket is the socket that will handle the actual the connection and has the same properties as socket s, including the asynchronous events registered with the WSAAsyncSelect or WSAEventSelect functions. The socket s does not have the listening socket's group ID, if any was applied.

The accept function can block the caller until a connection is present if no pending connections are present on the queue, and the socket is marked as blocking. If the socket is marked nonblocking and no pending connections are present on the queue, accept returns an error as described below. After the successful completion of accept returns a new socket handle, the accepted socket cannot be used to accept more connections. The original socket remains open and listens for new connection requests.

The parameter 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.

The accept function is used with connection-oriented 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.

Windows CE: Windows CE does not support the WSAEINTR error value.

For IrSocket implementation, the addr and addrlen parameters should always be NULL.

Return Values

If no error occurs, accept returns a value of type SOCKET that is a descriptor for the new socket. This returned value is a handle for the socket on which the actual connection will be made.

Otherwise, a value of INVALID_SOCKET is returned, and a specific error code can 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 FUNCTION.
WSAENETDOWN	The network subsystem has failed.
WSAEFAULT	The addrlen parameter is too small or addr is not a valid part of the user address space.
WSAEINTR	A blocking Windows Sockets 1.1 call was canceled through WSACancelBlockingCall.
WSAEINPROGRESS	A blocking Windows Sockets 1.1 call is in progress, or the service provider is still processing a callback function.
WSAEINVAL	The listen function was not invoked prior to accept.
WSAEMFILE	The queue is nonempty 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 nonblocking and no connections are present to be accepted.

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