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>
62 #define ICMP_NAMEREQ 37
63 #define ICMP_NAMEREP 38
65 unsigned char buf[65536];
67 /* DN decompression not yet implemented, since I don't know where to
68 * begin counting the offset from -- the beginning of the ICMP
69 * payload, or from the beginning of the DN data buffer? */
70 void printdn(FILE *f, unsigned char *dnbuf, size_t size, int onlyfirst)
75 while(p - dnbuf < size) {
78 fprintf(stderr, "domain name decompression not implemented, aborting\n");
81 fprintf(f, "%.*s", (int)*p, p + 1);
93 void cksum(void *hdr, size_t len)
100 ih = (struct icmphdr *)hdr;
101 cb = (u_int8_t *)hdr;
104 for(i = 0; i < (len & ~1); i += 2) {
123 cb = (u_int8_t *)&ih->checksum;
124 cb[0] = ~(u_int8_t)b1;
125 cb[1] = ~(u_int8_t)b2;
130 fprintf(stderr, "usage: idnlookup [-hTa] [-t timeout] host\n");
133 int main(int argc, char **argv)
143 struct addrinfo *ai, *cai, aihint;
145 struct timeval tvb, tvc;
146 struct sockaddr_storage name;
147 int timeout, dispttl, onlyfirst;
148 int elapsed, timedout, found;
153 while((c = getopt(argc, argv, "haTt:")) != -1) {
156 timeout = atoi(optarg);
169 exit((c == 'h')?0:1);
173 if(argc - optind < 1) {
178 memset(&aihint, 0, sizeof(aihint));
179 aihint.ai_socktype = SOCK_RAW;
180 aihint.ai_protocol = IPPROTO_ICMP;
181 ret = getaddrinfo(argv[optind], NULL, &aihint, &ai);
183 for(cai = ai; cai != NULL; cai = cai->ai_next) {
184 if((s = socket(cai->ai_family, SOCK_RAW, IPPROTO_ICMP)) < 0) {
185 perror("could not create raw socket");
189 id = random() % 65536;
190 memset(&req, 0, sizeof(req));
191 req.type = ICMP_NAMEREQ;
193 cksum(&req, sizeof(req));
195 ret = sendto(s, &req, sizeof(req), 0, cai->ai_addr, cai->ai_addrlen);
199 } else if(ret != sizeof(req)) {
200 fprintf(stderr, "socket would not send entire packet\n");
206 gettimeofday(&tvb, NULL);
210 gettimeofday(&tvc, NULL);
211 elapsed = ((tvc.tv_sec - tvb.tv_sec) * 1000) + ((tvc.tv_usec - tvb.tv_usec) / 1000);
212 if(elapsed >= timeout) {
216 ret = poll(&pfd, 1, timeout - elapsed);
218 perror("idnlookup: reading data");
222 if(pfd.revents & POLLIN) {
223 namelen = sizeof(name);
224 ret = recvfrom(s, buf, sizeof(buf), 0, (struct sockaddr *)&name, &namelen);
226 perror("idnlookup: receiving data");
230 if(name.ss_family != cai->ai_addr->sa_family)
232 if(name.ss_family == AF_INET) {
233 if(memcmp(&(((struct sockaddr_in *)&name)->sin_addr), &(((struct sockaddr_in *)cai->ai_addr)->sin_addr), sizeof(struct in_addr)))
235 if(ret < sizeof(iphdr) + sizeof(rep))
237 hdrlen = sizeof(iphdr);
238 memcpy(&iphdr, buf, sizeof(iphdr));
239 if(iphdr.protocol != IPPROTO_ICMP)
241 } else if(name.ss_family == AF_INET6) {
242 if(memcmp(&(((struct sockaddr_in6 *)&name)->sin6_addr), &(((struct sockaddr_in6 *)cai->ai_addr)->sin6_addr), sizeof(struct in6_addr)))
244 if(ret < sizeof(rep))
251 memcpy(&rep, buf + hdrlen, sizeof(rep));
252 if(rep.type != ICMP_NAMEREP)
254 if((ntohs(rep.id) != id) || (ntohs(rep.seq != 0)))
266 printf("%i\n", ntohl(rep.ttl));
267 printdn(stdout, buf + hdrlen + sizeof(rep), ret - hdrlen - sizeof(rep), onlyfirst);
273 fprintf(stderr, "idnlookup: timeout\n");
282 * compile-command: "gcc -Wall -g -o idnlookup idnlookup.c"