Method check_for_message

src/socket.cpp:673–788

Check for a message in the socket and return the length of the first * message. If this is UDP, the only check is if we have buffers. If this is * TCP or TLS we need to parse out the content-length. */

 * message.  If this is UDP, the only check is if we have buffers.  If this is
 * TCP or TLS we need to parse out the content-length. */
int SIPpSocket::check_for_message()
{
    struct socketbuf *socketbuf = ss_in;
    int state = ss_control ? CFM_CONTROL : CFM_NORMAL;
    const char *l;

    if (!socketbuf)
        return 0;

    if (ss_transport == T_UDP || ss_transport == T_SCTP) {
        return socketbuf->len;
    }

    int len = 0;

    while (socketbuf->offset + len < socketbuf->len) {
        char c = socketbuf->buf[socketbuf->offset + len];

        switch(state) {
        case CFM_CONTROL:
            /* For CMD Message the escape char is the end of message */
            if (c == 27) {
                return len + 1; /* The plus one includes the control character. */
            }
            break;
        case CFM_NORMAL:
            if (c == '\r') {
                state = CFM_CR;
            }
            break;
        case CFM_CR:
            if (c == '\n') {
                state = CFM_CRLF;
            } else {
                state = CFM_NORMAL;
            }
            break;
        case CFM_CRLF:
            if (c == '\r') {
                state = CFM_CRLFCR;
            } else {
                state = CFM_NORMAL;
            }
            break;
        case CFM_CRLFCR:
            if (c == '\n') {
                state = CFM_CRLFCRLF;
            } else {
                state = CFM_NORMAL;
            }
            break;
        }

        /* Head off failing because the buffer does not contain the whole header. */
        if (socketbuf->offset + len == socketbuf->len - 1) {
            merge_socketbufs(socketbuf);
        }