How To Use the WSAPROTOCOL_INFO Structure to Create a Socket

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Sample Code

   if (WSAStartup(MAKEWORD(2,2), &WSAData))
      printf("WSAStartup %d", WSAGetLastError());
   else
      {
      // First, have WSAEnumProtocols tell you how big a buffer you need.
      nRet = WSAEnumProtocols(NULL, lpProtocolBuf, &dwBufLen);
      if (SOCKET_ERROR != nRet)
         printf("WSAEnumProtocols: should not have succeeded\n");
      else if (WSAENOBUFS != (dwErr = WSAGetLastError()))
         // WSAEnumProtocols failed for some reason not relating to buffer
         // size - also odd.
         printf("WSAEnumProtocols(1): %d\n", WSAGetLastError());
      else
         {
         // WSAEnumProtocols failed for the "expected" reason. Therefore,
         // you need to allocate a buffer of the appropriate size.
         lpProtocolBuf = (WSAPROTOCOL_INFO *)malloc(dwBufLen);
         if (lpProtocolBuf)
            {
            // Now you can call WSAEnumProtocols again with the expectation
            // that it will succeed because you have allocated a big enough
            // buffer.
            nRet = WSAEnumProtocols(NULL, lpProtocolBuf, &dwBufLen);
            if (SOCKET_ERROR == nRet)
               printf("WSAEnumProtocols(3): %d\n", WSAGetLastError());
            else
               {
               // Loop through protocols, looking for the first service
               // provider that meets the matching criteria.
               bProtocolFound = FALSE;
               for (i=0; i<nRet; i++)
                  {
                  if ((IPPROTO_TCP == lpProtocolBuf[i].iProtocol) &&
                      (XP1_QOS_SUPPORTED == (XP1_QOS_SUPPORTED &
                       lpProtocolBuf[i].dwServiceFlags1)))
                     {
                     bProtocolFound = TRUE;
                     break;
                     }
                  }
               }
            }
         }
      }
				

    sd = WSASocket(
        FROM_PROTOCOL_INFO,
        FROM_PROTOCOL_INFO,
        FROM_PROTOCOL_INFO,
        &lpProtocolBuf[i],
        0,
        WSA_FLAG_OVERLAPPED);
    if (INVALID_SOCKET == sd)
        printf("WSASocket %d", WSAGetLastError());