send() not deliver all bytes?

Question

Why doesn\'t send() in winsock guarantee delivery of the all bytes you request?

This is TCP and it\'s blocking sockets.

Similarly,

Answer 1

This behaviour is "by design".

You can use an outer loop as shown in this example:

int sendBuffer (SOCKET ClientSocket, const char *buf, int len, int flags) 
  {
    int num_left = len;
    int num_sent;
    int err = 0;
    const char *cp = buf;

    while (num_left > 0) 
      {
        num_sent = send(ClientSocket, cp, num_left, flags);

        if (num_sent < 0) 
          {
            err = SOCKET_ERROR;
            break;
          }

        assert(num_sent <= num_left);

        num_left -= num_sent;
        cp += num_sent;
      }

    return (err == SOCKET_ERROR ?  SOCKET_ERROR : len);
  }