2 * idnlookup - ICMP Domain Name lookup utility for Linux
3 * Should be installed SUID root, even though I don't know if it's secure yet. :-)
4 * Copyright (C) 2005 Fredrik Tolf <fredrik@dolda2000.com>
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License, or
9 * (at your option) any later version.
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to the Free Software
18 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
26 #include <sys/socket.h>
27 #include <netinet/in.h>
28 #include <netinet/ip.h>
29 #include <netinet/ip6.h>
30 #include <arpa/inet.h>
31 #include <sys/types.h>
59 #define ICMP_NAMEREQ 37
60 #define ICMP_NAMEREP 38
62 unsigned char buf[65536];
64 /* DN decompression not yet implemented, since I don't know where to
65 * begin counting the offset from -- the beginning of the ICMP
66 * payload, or from the beginning of the DN data buffer? */
67 void printdn(FILE *f, unsigned char *dnbuf, size_t size, int onlyfirst)
72 while(p - dnbuf < size) {
75 fprintf(stderr, "domain name decompression not implemented, aborting\n");
78 fprintf(f, "%.*s", (int)*p, p + 1);
90 void cksum(void *hdr, size_t len)
97 ih = (struct icmphdr *)hdr;
101 for(i = 0; i < (len & ~1); i += 2) {
120 cb = (u_int8_t *)&ih->checksum;
121 cb[0] = ~(u_int8_t)b1;
122 cb[1] = ~(u_int8_t)b2;
127 fprintf(stderr, "usage: idnlookup [-hTa] [-t timeout] host\n");
130 int main(int argc, char **argv)
140 struct addrinfo *ai, *cai, aihint;
142 struct timeval tvb, tvc;
143 struct sockaddr_storage name;
144 int timeout, dispttl, onlyfirst;
145 int elapsed, timedout, found;
150 while((c = getopt(argc, argv, "haTt:")) != -1) {
153 timeout = atoi(optarg);
166 exit((c == 'h')?0:1);
170 if(argc - optind < 1) {
175 memset(&aihint, 0, sizeof(aihint));
176 aihint.ai_socktype = SOCK_RAW;
177 aihint.ai_protocol = IPPROTO_ICMP;
178 ret = getaddrinfo(argv[optind], NULL, &aihint, &ai);
180 for(cai = ai; cai != NULL; cai = cai->ai_next) {
181 if((s = socket(cai->ai_family, SOCK_RAW, IPPROTO_ICMP)) < 0) {
182 perror("could not create raw socket");
186 id = random() % 65536;
187 memset(&req, 0, sizeof(req));
188 req.type = ICMP_NAMEREQ;
190 cksum(&req, sizeof(req));
192 ret = sendto(s, &req, sizeof(req), 0, cai->ai_addr, cai->ai_addrlen);
196 } else if(ret != sizeof(req)) {
197 fprintf(stderr, "socket would not send entire packet\n");
203 gettimeofday(&tvb, NULL);
207 gettimeofday(&tvc, NULL);
208 elapsed = ((tvc.tv_sec - tvb.tv_sec) * 1000) + ((tvc.tv_usec - tvb.tv_usec) / 1000);
209 if(elapsed >= timeout) {
213 ret = poll(&pfd, 1, timeout - elapsed);
215 perror("idnlookup: reading data");
219 if(pfd.revents & POLLIN) {
220 namelen = sizeof(name);
221 ret = recvfrom(s, buf, sizeof(buf), 0, (struct sockaddr *)&name, &namelen);
223 perror("idnlookup: receiving data");
227 if(name.ss_family != cai->ai_addr->sa_family)
229 if(name.ss_family == AF_INET) {
230 if(memcmp(&(((struct sockaddr_in *)&name)->sin_addr), &(((struct sockaddr_in *)cai->ai_addr)->sin_addr), sizeof(struct in_addr)))
232 if(ret < sizeof(iphdr) + sizeof(rep))
234 hdrlen = sizeof(iphdr);
235 memcpy(&iphdr, buf, sizeof(iphdr));
236 if(iphdr.protocol != IPPROTO_ICMP)
238 } else if(name.ss_family == AF_INET6) {
239 if(memcmp(&(((struct sockaddr_in6 *)&name)->sin6_addr), &(((struct sockaddr_in6 *)cai->ai_addr)->sin6_addr), sizeof(struct in6_addr)))
241 if(ret < sizeof(rep))
248 memcpy(&rep, buf + hdrlen, sizeof(rep));
249 if(rep.type != ICMP_NAMEREP)
251 if((ntohs(rep.id) != id) || (ntohs(rep.seq != 0)))
263 printf("%i\n", ntohl(rep.ttl));
264 printdn(stdout, buf + hdrlen + sizeof(rep), ret - hdrlen - sizeof(rep), onlyfirst);
270 fprintf(stderr, "idnlookup: timeout\n");
279 * compile-command: "gcc -Wall -g -o idnlookup idnlookup.c"