connect()

Description

Establish a connection to a peer.

#include <winsock.h>

int PASCAL FAR connect ( SOCKET s, const struct sockaddr FAR * name, int namelen);

s

A descriptor identifying an unconnected socket.
name
The name of the peer to which the socket is to be connected.
namelen
The length of the name.

Remarks

This function is used to create a connection to the specified foreign association. The parameter s specifies an unconnected datagram or stream socket If the socket is unbound, unique values are assigned to the local association by the system, and the socket is marked as bound. Note that if the address field of the name structure is all zeroes, connect() will return the error WSAEADDRNOTAVAIL.

For stream sockets (type SOCK_STREAM), an active connection is initiated to the foreign host using name (an address in the name space of the socket). When the socket call completes successfully, the socket is ready to send/receive data.

For a datagram socket (type SOCK_DGRAM), a default destination is set, which will be used on subsequent send() and recv() calls.

On a non-blocking socket, if the return value is SOCKET_ERROR an application should call WSAGetLastError() If this indicates an error code of WSAEWOULDBLOCK, then your application can either:

• Use select() to determine the completion of the connection request by checking if the socket is writeable, or

• If your application is using the message-based WSAAsyncSelect() to indicate interest in connection events, then your application will receive an FD_CONNECT message when the connect operation is complete.

Return Value

If no error occurs, connect() returns 0. Otherwise, it returns SOCKET_ERROR, and a specific error code may be retrieved by calling WSAGetLastError()

On a blocking socket, the return value indicates success or failure of the connection attempt.

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.
WSAEADDRINUSE
The specified address is already in use.
WSAEINTR
The (blocking) call was canceled via WSACancelBlockingCall()
WSAEINPROGRESS
A blocking Windows Sockets call is in progress.
WSAEADDRNOTAVAIL
The specified address is not available from the local machine.
WSAEAFNOSUPPORT
Addresses in the specified family cannot be used with this socket.
WSAECONNREFUSED
The attempt to connect was forcefully rejected.
WSAEDESTADDREQ
A destination address is required.
WSAEFAULT
The namelen argument is incorrect.
WSAEINVAL
The socket is not already bound to an address.
WSAEISCONN
The socket is already connected.
WSAEMFILE
No more file descriptors are available.
WSAENETUNREACH
The network can't be reached from this host at this time.
WSAENOBUFS
No buffer space is available. The socket cannot be connected.
WSAENOTSOCK
The descriptor is not a socket.
WSAETIMEDOUT
Attempt to connect timed out without establishing a connection
WSAEWOULDBLOCK
The socket is marked as non-blocking and the connection cannot be completed immediately. It is possible to select() the socket while it is connecting by select()ing it for writing.

See Also

accept(), bind(), getsockname(), socket(), and WSAAsyncSelect

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