Is there any way to ping a specific IP address with C?

Question

Is there any way to ping a specific IP address with C? If I wanted to ping "www.google.com" with a certain number of pings, or for that matter, a local address, I would need a program to do that. How can I ping from C?

Answer 1

There is no accepted answer yet and I stumbled upon this question while trying to do exactly what was asked here so I wanted to refer to Aif's answer here.
The following code is based on his example and pings Google's public DNS in a child process and prints the output in the parent process.

#include <sys/wait.h>
#include <unistd.h>
#include <stdio.h>

#define BUFLEN 1024

int main(int argc, char **argv)
{
    int pipe_arr[2];
    char buf[BUFLEN];

    //Create pipe - pipe_arr[0] is "reading end", pipe_arr[1] is "writing end"
    pipe(pipe_arr);

    if(fork() == 0) //child
    {
        dup2(pipe_arr[1], STDOUT_FILENO);
        execl("/sbin/ping", "ping", "-c 1", "8.8.8.8", (char*)NULL);    
    }
    else //parent
    {
        wait(NULL);
        read(pipe_arr[0], buf, BUFLEN);
        printf("%s\n", buf);

    }

    close(pipe_arr[0]);
    close(pipe_arr[1]);
    return 0;
}

Answer 2

You could craft your own ICMP packets using raw sockets, but that's far from trivial. The source code for ping(1) is a good place to start on figuring out how to do that (it uses a BSD-like license; see the source code for the full license). Keep in mind that raw sockets require root privileges on Linux, so your program will need to be setuid root.

Of course, it's much easier to shell out to the ping(1) executable and not have to deal with any of this yourself. You won't have to worry about code licensing, and your program won't need root privileges (assuming it doesn't already need them for something else). system(3), popen(3), and fork(3)/exec(3) are your friends.