C socket programming under windows

Question

Hi I'm new to socket programming and I'm trying out the following code from the tutorial of http://www.binarytides.com/winsock-socket-programming-tutorial/

I'm trying to connect to server and I'm using the IP address of google. Here is the code:

#include<stdio.h>
#include<winsock2.h>

#pragma comment(lib,"ws2_32.lib") //Winsock Library

int main(int argc , char *argv[])
{
    WSADATA wsa;
    SOCKET s;
    struct sockaddr_in server;

    printf("\nInitialising Winsock...");
    if (WSAStartup(MAKEWORD(2,2),&wsa) != 0)
    {
        printf("Failed. Error Code : %d",WSAGetLastError());
        return 1;
    }

    printf("Initialised.\n");

    //Create a socket
    if((s = socket(AF_INET , SOCK_STREAM , 0 )) == INVALID_SOCKET)
    {
        printf("Could not create socket : %d" , WSAGetLastError());
    }

    printf("Socket created.\n");


    server.sin_addr.s_addr = inet_addr("74.125.224.72");
    server.sin_family = AF_INET;
    server.sin_port = htons(80);

    //Connect to remote server
    if (connect(s, (struct sockaddr *)&server , sizeof(server)) < 0)
    {
        puts("connect error");
        return 1;
    }

    puts("Connected");

    return 0;
}

So far socket can be created but I can't connect to the server. To be more specific I always exit and have following:

The program '[2060] SocketCTest.exe: Native' has exited with code 1 (0x1).

even if I set a breakpoint before returns.

Answer 1

There's no error. I've tried on my computer and connect returned with error ( WSAETIMEDOUT ). I'm not sure whether there are the network settings on my computer, proxies, firewalls, and so on; or that google host is configured not to accept direct socket connections.

Anyway here's your code with some small adjustments:

#include <stdio.h>
#include <conio.h>
#include <winsock2.h>
#pragma comment(lib, "ws2_32.lib") //Winsock Library

int main(int argc, char *argv[])
{
    WSADATA wsa;
    SOCKET s;
    struct sockaddr_in server;
    char c = 0;

    printf("\nInitialising Winsock...");
    if (WSAStartup(MAKEWORD(2,2), &wsa) != 0)
    {
        printf("Failed. Error Code : %d.\nPress a key to exit...", WSAGetLastError());
        c = getch();
        return 1;
    }

    printf("Initialised.\n");

    //Create a socket
    if((s = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP)) == INVALID_SOCKET)
    {
        printf("Could not create socket : %d.\n", WSAGetLastError());
        WSACleanup();
        c = getch();
        return 1;
    }
    printf("Socket created. Connecting...\n");
    memset(&server, 0, sizeof server);
    server.sin_addr.s_addr = inet_addr("74.125.224.72");
    server.sin_family = AF_INET;
    server.sin_port = htons(80);

    //Connect to remote server
    if (connect(s, (struct sockaddr *)&server, sizeof(server)) < 0)
    {
        printf("Connect error:%d.\nPress a key to exit...", WSAGetLastError());
        closesocket(s);
        WSACleanup();
        c = getch();
        return 1;
    }
    puts("Connected.\nPress a key to exit...");
    closesocket(s);
    WSACleanup();
    c = getch();
    return 0;
}

Now if you want to see the code actually connecting i'd suggest using localhost ( 127.0.0.1 ) instead of 74.125.224.72 , and the port 3389 for example (it's the Remote Desktop Server (RDP) port, if you have RDP configured and running on your computer) instead of 80 ; or you could let 80 if you have a web server ( IIS ?) running on your computer.

To get a list of server programs that run on your computer run the command:

`netstat -an | findstr LISTEN`

which would output a bunch of lines (and the ones that we care about are) in this form (here's the one corresponding to the RDP example from above):

`TCP    127.0.0.1:3389         0.0.0.0:0              LISTENING`