Quick and dirty program to get addrinfo.

getaddrinfo.c

// compile: clang -o getaddrinfo getaddrinfo.c

#include <stdio.h>
#include <string.h>
#include <unistd.h>

#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>
#include <errno.h>
#include <stdlib.h>

char * family_type(int af) {
    switch (af) {
        case AF_INET:
            return "AF_INET";
        case AF_INET6:
            return "AF_INET6";
        default:
            return "UNKNOWN";
    }
}

int main(int argc, char* argv[]) {
    struct addrinfo hints, *addrlist, *addr;
    struct socket_links *head, *current;

    memset(&hints, 0, sizeof(hints));
    // Ask for TCP
    hints.ai_socktype = SOCK_STREAM;
    // Any family works for us ...
    hints.ai_family = AF_UNSPEC;
    // Set some hints
    hints.ai_flags =
        AI_PASSIVE      | // We want to use this with bind
        AI_NUMERICSERV;   // We only pass in numeric port numbers
    int rv;

    if ((rv = getaddrinfo(argv[1], "80", &hints, &addrlist)) != 0) {
        fprintf(stderr, "getaddrinfo: %s", gai_strerror(rv));
        return 1;
    }

    for (addr = addrlist; addr != 0; addr = addr->ai_next) {
        struct protoent *proto = getprotobynumber(addr->ai_protocol);
        
        printf("Address family: %s (%d)\tSocket type: %s (%d)\tProtocol: %s (%d)\n", 
                family_type(addr->ai_family), 
                addr->ai_family, 
                addr->ai_socktype == SOCK_STREAM ? "SOCK_STREAM" : "other", 
                addr->ai_socktype, 
                proto->p_name, 
                addr->ai_protocol);
    }

    freeaddrinfo(addrlist);

    return 0;
}