C - getaddrinfo()

Question

Can someone help me to get the IPs of google.com?

I can't find any good resource on this.
Most tutorials on C network programming create a client socket and a server socket on the same computer. (I don't know in which situation that would make sense)
And none of the codes on beej.us worked for me.

#include <stdio.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <netdb.h>

int main(void)
{
    struct addrinfo* res = NULL;
    getaddrinfo("google.com", "443", 0, &res);

    struct addrinfo* i;

    for(i=res; i!=0; res=res->ai_next)
    {
        printf("%s\n", res->ai_addr->sa_data);
    }
}

Output:

�
�
�
���$u
���$u
���$u
���"u
���"u
���"u
��� u
��� u
��� u
���&u
���&u
���&u
Segmentation fault

Answer 1

In This statement i is never being modified in loop body, and because it is not initialized, it never even enters the loop:

for(i=res; i!=0; res=res->ai_next)
{
    printf("%s\n", res->ai_addr->sa_data);
}

Additionally, you are missing a few other parts. The following steps are part of a full example linked below:

Create the following instances of struct addrinfo:

struct addrinfo *result = NULL;
struct addrinfo *ptr = NULL;
struct addrinfo hints;

Then initialize Winsock

   // Initialize Winsock
    iResult = WSAStartup(MAKEWORD(2, 2), &wsaData);

Setup the hints address info structure

ZeroMemory( &hints, sizeof(hints) );
hints.ai_family = AF_UNSPEC;
hints.ai_socktype = SOCK_STREAM;
hints.ai_protocol = IPPROTO_TCP;

Call getaddrinfo

dwRetval = getaddrinfo(argv[1], argv[2], &hints, &result);
if ( dwRetval != 0 ){//handle error}

Now, for example based on above, your loop would look like:

   for(ptr=result; ptr != NULL ;ptr=ptr->ai_next) {//

Entering "www.google.com" 0 on the command line for the complete example (linked below) will look similar to this:

This full Windows example is here. Note: Bug in code, i.e. ptr->ai_cannonname can be null with "www.google.com" so change this line to test before calling:

if(ptr->ai_canonname) printf("\tCanonical name: %s\n", ptr->ai_canonname);

A full Linux example is here.