WSASendToSOCKET

WSASendTo is a Windows Sockets API function used to send data over a socket. It is part of the Winsock 2 API. This function is employed for both connection-oriented and connectionless sockets. When used with a connection-oriented socket like SOCK_STREAM, the destination address information is typically ignored if the socket is already connected. However, for connectionless sockets, such as SOCK_DGRAM, WSASendTo is essential for specifying the destination endpoint for the data packet.

The function takes several arguments, including a socket handle, a buffer containing the data to be sent, the size of the buffer, the number of bytes actually sent, flags that modify the function's behavior, a pointer to a sockaddr structure containing the destination address, and the size of the sockaddr structure. A successful call to WSASendTo returns zero. A return value of SOCKET_ERROR indicates an error occurred, and WSAGetLastError can be used to retrieve the specific error code.

WSASendTo allows for asynchronous operation by passing the WSAOVERLAPPED structure. This enables the application to continue performing other tasks while the data transmission occurs in the background. Completion of the asynchronous send operation can be signaled through events, I/O completion ports, or completion routines. The function is crucial for network applications that need to transmit data to specific remote hosts and ports.