gho.c

/*
 * Excessively long hostname lookup on Mac OS X Snow Leopard 
 *
 * gcc -g -Wall -o gho gho.c
 * ./gho 69982
 *
 * Feb 15 12:42:47 ack mDNSResponder[18]:  77: ERROR: read_msg - hdr.datalen 70001 (11171) > 70000
 * Feb 15 12:42:47 ack ./gho[4852]: dnssd_clientstub write_all(4) failed -1/70028 32 Broken pipe
 * Feb 15 12:42:47 ack ./gho[4852]: dnssd_clientstub deliver_request ERROR: write_all(4, 70028 bytes) failed
 * Feb 15 12:42:47 ack ./gho[4852]: dnssd_clientstub write_all(4) failed -1/28 32 Broken pipe
 *
 */

#include <stdio.h>
#include <stdlib.h>
#include <netdb.h>
#include <err.h>
#include <string.h>

int
main (int argc, char *argv[])
{
    char *host = NULL;
    size_t len = 0;
    struct hostent *he = NULL;


    if (argc != 2)
        errx(EXIT_FAILURE, "%s: <length>", argv[0]);

    len = (size_t)atoi(argv[1]) + 1;

    host = calloc(len, 1);
    if (host == NULL)
        err(EXIT_FAILURE, "calloc");

    (void)memset(host, 'x', len-1);

    (void)printf("Length = %lu\n", strlen(host));

    he = gethostbyname(host);
    if (he == NULL)
        errx(EXIT_FAILURE, "Error resolving: %s", host);

    (void)printf("Official hostname = %s\n", he->h_name);

    exit(0);
}