WSPConnect (Compact 2013)

3/26/2014

This function establishes a connection to a peer, and exchanges connect data.

Syntax

int WSPConnect(
  SOCKET s,
  const struct sockaddr FAR* name,
  int namelen,
  LPWSABUF lpCallerData,
  LPWSABUF lpCalleeData,
  LPQOS lpSQOS,
  LPQOS lpGQOS,
  LPINT lpErrno 
);

Parameters

• s
  [in] Descriptor identifying an unconnected socket.

• name
  [in] Name of the peer to which the socket is to be connected.

• namelen
  [in] Length of the name.

• lpCallerData
  [in] Pointer to the user data that is to be transferred to the peer during connection establishment.

• lpCalleeData
  [out] Pointer to a buffer into which any user data received from the peer during connection establishment can be copied.

• lpSQOS
  [in] Reserved.

• lpGQOS
  [in] Reserved.

• lpErrno
  [out] Pointer to the error code.

Return Value

If no error occurs, this function returns zero. Otherwise, it returns SOCKET_ERROR, and a specific error code is available in lpErrno.

On a blocking socket, the return value indicates success or failure of the connection attempt. If the return error code indicates the connection attempt failed (that is, WSAECONNREFUSED, WSAENETUNREACH, WSAETIMEDOUT) the Windows Sockets SPI client can call WSPConnect again for the same socket.

The following table shows the possible error codes.

Remarks

This function is used to create a connection to the specified destination and to perform a number of other ancillary operations that occur at connect time as well. If the socket, s, is unbound, unique values are assigned to the local association by the system and the socket is marked as bound.

For connection-oriented sockets (for example, type SOCK_STREAM), an active connection is initiated to the specified host using name (an address in the name space of the socket. (For a detailed description, see WSPBind.) When this call completes successfully, the socket is ready to send and receive data. If the address member of the name structure is all zeroes, WSPConnect will return the error WSAEADDRNOTAVAIL. Any attempt to reconnect an active connection will fail with the error code WSAEISCONN.

For connection-oriented, nonblocking sockets it is often not possible to complete the connection immediately. In such a case, this function returns with the error WSAEWOULDBLOCK but the operation proceeds. When the success or failure outcome becomes known, it may be reported in one of several ways depending on how the client registers for notification. If the client uses WSPSelect, success is reported in the writefds set and failure is reported in the exceptfds set. If the client uses WSPEventSelect, the notification is announced with FD_CONNECT and the error code associated with the FD_CONNECT indicates either success or a specific reason for failure.

For a connectionless socket (for example, type SOCK_DGRAM), the operation performed by WSPConnect is to establish a default destination address so the socket can be used with subsequent connection-oriented send and receive operations (WSPSend, WSPRecv). Any datagrams received from an address other than the destination address specified will be discarded. If the address member of the name structure is all zeroes, the socket will be disconnected- the default remote address will be indeterminate, so WSPSend and WSPRecv calls will return the error code WSAENOTCONN. However, WSPSendTo and WSPRecvFrom can still be used. The default destination can be changed by simply calling WSPConnect again, even if the socket is already connected. Any datagrams queued for receipt are discarded if name is different from the previous WSPConnect.

For connectionless sockets, name can indicate any valid address, including a broadcast address. However, to connect to a broadcast address, a socket must have WSPSetSockOpt SO_BROADCAST enabled. Otherwise, WSPConnect will fail with the error code WSAEACCES.

On connectionless sockets, exchange of user-to-user data is not possible and the corresponding parameters will be silently ignored.

The Windows Sockets SPI client is responsible for allocating any memory space pointed to directly or indirectly by any of the parameters it specifies.

The lpCallerData is a value parameter that contains any user data to be sent along with the connection request. If lpCallerData is NULL, no user data will be passed to the peer. The lpCalleeData is a result parameter that will reference any user data passed back from the peer as part of the connection establishment. The lpCalleeData->len initially contains the length of the buffer allocated by the Windows Sockets SPI client and pointed to by lpCalleeData->buf. The lpCalleeData->len will be set to zero if no user data has been passed back. The lpCalleeData information will be valid when the connection operation is complete. For blocking sockets, this will be when the WSPConnect function returns. For nonblocking sockets, this will be after the FD_CONNECT notification has occurred. If lpCalleeData is NULL, no user data will be passed back. The exact format of the user data is specific to the address family the socket belongs to and/or the applications involved.

Requirements

See Also

Reference

Winsock SPI Functions
WSPAccept
WSPBind
WSPGetSockName
WSPGetSockOpt
WSPSocket
WSPSelect
WSPEventSelect
WSPEnumNetworkEvents