dnsresolve.c
author Markus Bröker <mbroeker@largo.dyndns.tv>
Fri, 27 Dec 2013 16:00:09 +0100
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/**
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 * dnsresolve.c
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 * Copyright (C) 2008 Markus Broeker
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 */
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/types.h>
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#include <sys/socket.h>
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#include <arpa/inet.h>
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#include <netdb.h>
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#include <netinet/in.h>
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int main (int argc, char **argv)
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{
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    struct addrinfo hints;
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    struct addrinfo *result, *rp;
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    void *addr = NULL;
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    char ip[INET6_ADDRSTRLEN];
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    if (argc != 2) {
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        fprintf (stderr, "Usage: %s <hostname>\n", argv[0]);
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        return EXIT_FAILURE;
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    }
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    memset (&hints, 0, sizeof (hints));
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    hints.ai_family = AF_UNSPEC;
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    hints.ai_socktype = SOCK_STREAM;
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    if (getaddrinfo (argv[1], NULL, &hints, &result) != 0) {
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        perror ("getaddrinfo");
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        return EXIT_FAILURE;
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    }
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    for (rp = result; rp != NULL; rp = rp->ai_next) {
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        if (rp->ai_family == AF_INET6) {
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            struct sockaddr_in6 *ipv6 = (struct sockaddr_in6 *)rp->ai_addr;
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            addr = &(ipv6->sin6_addr);
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        } else if (rp->ai_family == AF_INET) {
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            struct sockaddr_in *ipv4 = (struct sockaddr_in *)rp->ai_addr;
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            addr = &(ipv4->sin_addr);
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        }
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        if (addr != NULL) {
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            if (inet_ntop (rp->ai_family, addr, ip, sizeof (ip)) != NULL)
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                printf ("%s: %s\n", argv[1], ip);
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        }
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    }
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    if (result != NULL)
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        freeaddrinfo (result);
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    return EXIT_SUCCESS;
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}