CODEWITHSUNDEEP
csockets
NlightNFotis
NlightNFotis

Reputation: 9803

Socket fails to accept a client?

I am trying to get my feet wet with network programming. I have created a server, that accepts a connection from a web client.

At some point (I can not recall when) it broke, and for the life of me, I can not get it fixed.

Could someone at least provide me with some pointers? (No pun intended)

I have tried all there is, read the whole web, including the gnu c library documentation (I am on linux) but still no luck.

EDIT: Description of the problem: My client software manages to connect, however the server software doesn't report on that, and seems to get stuck at the accept() function.

My code:

#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include "lib/error.h"
#include <string.h>
#include <sys/types.h>
#include <time.h>

int main(int argc, char *argv[])
{
    int socketfd = 0, connfd = 0; // socket, and connection file descriptors
    struct sockaddr_in serv_addr; // struct that will get filled with host info
    struct sockaddr_in cli_addr; // struct that will get filled with peer info
    int status; // Used for various status controling and error messaging throughout the program

    char sendBuff[1025]; // buffer to allow for storage of items to be sent
    socklen_t cli_size = sizeof(cli_addr);
    time_t ticks;

    socketfd = socket(AF_INET, SOCK_STREAM, 0); // Creating a socket
    if (socketfd == -1) error("Failed to create socket.", 4);

    memset(&serv_addr, '0', sizeof(serv_addr)); // zeroing out the location of serv_addr
    memset(&cli_addr, '0', sizeof(cli_addr)); // zeroing out the location of serv_addr
    memset(sendBuff, '0', sizeof(sendBuff)); // zeroing out the locaiton of sendBuff

    serv_addr.sin_family = AF_INET;
    serv_addr.sin_addr.s_addr = htonl(INADDR_ANY);
    serv_addr.sin_port = htons(5000);

    status = bind(socketfd, (struct sockaddr *) &serv_addr, sizeof(serv_addr));
    if (status == -1) error("Failed to bind socket.", 4);

    listen(socketfd, 10);

    while(1)
    {
        connfd = accept(socketfd, (struct sockaddr *) &cli_addr, (socklen_t *) &cli_size);
        if (connfd == -1) error("Failed during accepting the peer connection at socket.", 3);

        printf("Client connected: %d:%d", cli_addr.sin_addr.s_addr, cli_addr.sin_port);

        close(connfd);
        sleep(1);
    }

    return 0;
}

Upvotes: 0

Views: 4259

Answers (1)

cnicutar
cnicutar

Reputation: 182724

As speculated in the comments, the problem is buffering. In a nutshell, the client connects, accept returns a valid socket and printf is called but the output simply doesn't get onto the screen.

As Roddy mentioned, adding a newline might fix it because on many implementations stdout is line-buffered, i.e. when you write a newline it automatically flushes everything. However, that isn't required by the standard so the safest cleanest way to ensure the output does go to the device is fflush.

As Chris Hayes mentioned, you probably want memset(&serv_addr, 0, sizeof serv_addr) and you don't need the cast in (socklen_t *) &cli_size.

Upvotes: 2

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