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Full Discussion: TCP connection check
Top Forums Programming TCP connection check Post 302533279 by Shang on Thursday 23rd of June 2011 07:22:49 AM
Old 06-23-2011
I put some info printing to my code in order to examine where function execution breaks. Now it lookes like that:
Code:
/***
 * Sends request through socket
 * Returns:
 *             0    success
 *             -1    buffer memory allocation failed
 */
int send_request(int socket, request_s *request) {
    char *buffer;

    if ((buffer = (char *) malloc(MSG_SIZE)) == NULL) {
        ERR("malloc");
        return -1;
    }
    int i;
    request_to_string(request, buffer);
    printf("send_request: before send\n");
    if ((i = send(socket, buffer, MSG_SIZE, 0)) < 0) {
        free(buffer);
        ERR("send");
    }
    printf("send_request: bytes sent: %d\n",i);
    printf("send_request: after send\n");
    free(buffer);
    return 0;
}
int communicate(int socket, request_s *request, response_s *response) {
    fd_set rfds;
    sigset_t mask, old_mask;
    char buffer[MSG_SIZE];
    memset(&buffer, 65, MSG_SIZE * sizeof(char));
    printf("communicate: beginning\n");
    if (request == NULL)
        return -1;
    else {
        if (send_request(socket, request) < 0) {
            printf("Sending request failed.\n");
            return -2;
        }
    }
    printf("communicate: after sending request\n");
    FD_ZERO(&rfds);
    FD_SET(socket, &rfds);
    sigemptyset(&mask);
    sigaddset(&mask, SIGINT);
    sigprocmask(SIG_BLOCK, &mask, &old_mask);

    if (pselect(socket + 1, &rfds, NULL, NULL, NULL, &old_mask) > 0) {
        if (FD_ISSET(socket, &rfds)) {
            if (TEMP_FAILURE_RETRY(recv(socket, (void *) buffer, MSG_SIZE, 0))
                    < 0)
                return -3;
            string_to_response(buffer, response);
            printf("communicate: buffer: %s\n", buffer);
            return 0;
        }
    }
    if (errno == EINTR) {
        request->type = MSG_EXIT_REQ;
        send_request(socket, request);
        TEMP_FAILURE_RETRY(close(socket));
        exit(EXIT_FAILURE);
    }
    return -4;
}

Here is also console output from client, when server is broken:
Code:
:~$ 5
send_scores_request: beginning
communicate: beginning
send_request: before send
send_request: bytes sent: 150
send_request: after send
communicate: after sending request
communicate: buffer: AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
send_scores_request: after communicate
Invalid response from the server (not MSG_SCORES_RSP)
1 - Show board
2 - Show my tiles
3 - Check whose turn it is
4 - Make a move
5 - Show scores

6 - Exit

:~$ 5
send_scores_request: beginning
communicate: beginning
send_request: before send

Remarks:
1. Don't worry about those AAAAA... in buffer. I made memset(&buffer, 65...) at the beginning in order to better visualise if there something changes in the buffer, apparently not.
2. As you can see, menu position 5 has been invoked twice. As I said before, first time send does not return any error, also recv neither returns any error nor changes the buffer. Second time program quits.

It is a very strange situation. For now I don't even know where to find a mistake Smilie
 

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SOCKET_WRITE(3) 							 1							   SOCKET_WRITE(3)

socket_write - Write to a socket

SYNOPSIS
int socket_write (resource $socket, string $buffer, [int $length]) DESCRIPTION
The function socket_write(3) writes to the $socket from the given $buffer. PARAMETERS
o $socket - o $buffer - The buffer to be written. o $length - The optional parameter $length can specify an alternate length of bytes written to the socket. If this length is greater than the buffer length, it is silently truncated to the length of the buffer. RETURN VALUES
Returns the number of bytes successfully written to the socket or FALSE on failure. The error code can be retrieved with socket_last_error(3). This code may be passed to socket_strerror(3) to get a textual explanation of the error. Note It is perfectly valid for socket_write(3) to return zero which means no bytes have been written. Be sure to use the === operator to check for FALSE in case of an error. NOTES
Note socket_write(3) does not necessarily write all bytes from the given buffer. It's valid that, depending on the network buffers etc., only a certain amount of data, even one byte, is written though your buffer is greater. You have to watch out so you don't uninten- tionally forget to transmit the rest of your data. SEE ALSO
socket_accept(3), socket_bind(3), socket_connect(3), socket_listen(3), socket_read(3), socket_strerror(3). PHP Documentation Group SOCKET_WRITE(3)
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