/usr/share/doc/libudns-dev/examples/ex-rdns.c is in libudns-dev 0.4-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 | /* ex-rdns.c
parallel rDNS resolver example - read IP addresses from stdin,
write domain names to stdout
Copyright (C) 2005 Michael Tokarev <mjt@corpit.ru>
This file is part of UDNS library, an async DNS stub resolver.
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library, in file named COPYING.LGPL; if not,
write to the Free Software Foundation, Inc., 59 Temple Place,
Suite 330, Boston, MA 02111-1307 USA
*/
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <sys/poll.h>
#include <unistd.h>
#include <stdio.h>
#include <time.h>
#include <stdlib.h>
#include <string.h>
#include "udns.h"
static int curq;
static const char *n2ip(const unsigned char *c) {
static char b[sizeof("255.255.255.255")];
sprintf(b, "%u.%u.%u.%u", c[0], c[1], c[2], c[3]);
return b;
}
static void dnscb(struct dns_ctx *ctx, struct dns_rr_ptr *rr, void *data) {
const char *ip = n2ip((unsigned char *)&data);
int i;
--curq;
if (rr) {
printf("%s", ip);
for(i = 0; i < rr->dnsptr_nrr; ++i)
printf(" %s", rr->dnsptr_ptr[i]);
putchar('\n');
free(rr);
}
else
fprintf(stderr, "%s: %s\n", ip, dns_strerror(dns_status(ctx)));
}
int main(int argc, char **argv) {
int c;
time_t now;
int maxq = 10;
struct pollfd pfd;
char linebuf[1024];
char *eol;
int eof;
if (dns_init(NULL, 1) < 0) {
fprintf(stderr, "unable to initialize dns library\n");
return 1;
}
while((c = getopt(argc, argv, "m:r")) != EOF) switch(c) {
case 'm': maxq = atoi(optarg); break;
case 'r':
dns_set_opt(0, DNS_OPT_FLAGS,
dns_set_opt(0, DNS_OPT_FLAGS, -1) | DNS_NORD);
break;
default: return 1;
}
if (argc != optind) return 1;
pfd.fd = dns_sock(0);
pfd.events = POLLIN;
now = time(NULL);
c = optind;
eof = 0;
while(curq || !eof) {
if (!eof && curq < maxq) {
union { struct in_addr a; void *p; } pa;
if (!fgets(linebuf, sizeof(linebuf), stdin)) {
eof = 1;
continue;
}
eol = strchr(linebuf, '\n');
if (eol) *eol = '\0';
if (!linebuf[0]) continue;
if (dns_pton(AF_INET, linebuf, &pa.a) <= 0)
fprintf(stderr, "%s: invalid address\n", linebuf);
else if (dns_submit_a4ptr(0, &pa.a, dnscb, pa.p) == 0)
fprintf(stderr, "%s: unable to submit query: %s\n",
linebuf, dns_strerror(dns_status(0)));
else
++curq;
continue;
}
if (curq) {
c = dns_timeouts(0, -1, now);
c = poll(&pfd, 1, c < 0 ? -1 : c * 1000);
now = time(NULL);
if (c)
dns_ioevent(0, now);
}
}
return 0;
}
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