+++ /dev/null
-/*
- * icmpdnd - ICMP Domain Name responder daemon for Linux
- * Copyright (C) 2005 Fredrik Tolf <fredrik@dolda2000.com>
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program 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 General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
-*/
-#include <stdlib.h>
-#include <unistd.h>
-#include <stdio.h>
-#include <string.h>
-#include <errno.h>
-#include <syslog.h>
-#include <time.h>
-#include <sys/socket.h>
-#include <sys/poll.h>
-#include <netinet/in.h>
-#include <arpa/inet.h>
-#include <netinet/ip.h>
-#include <sys/types.h>
-
-struct icmphdr {
- u_int8_t type;
- u_int8_t code;
- u_int16_t checksum;
-};
-
-struct reqhdr {
- u_int8_t type;
- u_int8_t code;
- u_int16_t checksum;
- u_int16_t id;
- u_int16_t seq;
-};
-
-struct rephdr {
- u_int8_t type;
- u_int8_t code;
- u_int16_t checksum;
- u_int16_t id;
- u_int16_t seq;
- int32_t ttl;
-};
-
-#define ICMP_NAMEREQ 37
-#define ICMP_NAMEREP 38
-
-volatile int alive;
-
-size_t filldn(char *dst)
-{
- char *p, *p2, *dp;
- char namebuf[1024];
- int hl;
-
- if(gethostname(namebuf, sizeof(namebuf)) < 0) {
- perror("gethostname");
- exit(1);
- }
- hl = strlen(namebuf);
- namebuf[hl++] = '.';
- if(getdomainname(namebuf + hl, sizeof(namebuf) - hl) < 0) {
- perror("getdomainname");
- exit(1);
- }
- if(strlen(namebuf + hl) != 0) {
- hl = strlen(namebuf);
- namebuf[hl++] = '.';
- }
- namebuf[hl] = 0;
-
- p = namebuf;
- dp = dst;
- while((p2 = strchr(p, '.')) != NULL) {
- *p2 = 0;
- *(dp++) = p2 - p;
- memcpy(dp, p, p2 - p);
- dp += p2 - p;
- p = p2 + 1;
- }
- *(dp++) = 0;
-
- return(dp - dst);
-}
-
-void cksum(void *hdr, size_t len)
-{
- struct icmphdr *ih;
- u_int8_t *cb;
- int i;
- int b1, b2;
-
- ih = (struct icmphdr *)hdr;
- cb = (u_int8_t *)hdr;
- ih->checksum = 0;
- b1 = b2 = 0;
- for(i = 0; i < (len & ~1); i += 2) {
- b1 += cb[i];
- b2 += cb[i + 1];
- }
- if(i & 1)
- b1 += cb[len - 1];
- while(1) {
- if(b1 >= 256) {
- b2 += b1 >> 8;
- b1 &= 0xff;
- continue;
- }
- if(b2 >= 256) {
- b1 += b2 >> 8;
- b2 &= 0xff;
- continue;
- }
- break;
- }
- cb = (u_int8_t *)&ih->checksum;
- cb[0] = ~(u_int8_t)b1;
- cb[1] = ~(u_int8_t)b2;
-}
-
-int main(int argc, char **argv)
-{
- int i, n, ret;
- int c, cs, s4, s6, datalen;
- int daemonize, ttl;
- unsigned char buf[65536];
- struct sockaddr_storage name;
- struct reqhdr req;
- struct rephdr rep;
- struct iphdr iphdr;
- struct msghdr mhdr;
- struct iovec iov;
- char cmsgbuf[CMSG_SPACE(sizeof(struct in6_pktinfo))];
- size_t hdrlen;
- struct pollfd pfd[2];
- time_t curtime, lasterr;
-
- daemonize = 1;
- ttl = 3600;
- while((c = getopt(argc, argv, "nht:")) != -1) {
- switch(c) {
- case 't':
- ttl = atoi(optarg);
- break;
- case 'n':
- daemonize = 0;
- break;
- case 'h':
- case '?':
- case ':':
- default:
- fprintf(stderr, "usage: icmpdnd [-n]");
- exit((c == 'h')?0:1);
- }
- }
-
- s4 = socket(PF_INET, SOCK_RAW, IPPROTO_ICMP);
- s6 = socket(PF_INET6, SOCK_RAW, IPPROTO_ICMP);
- if((s4 < 0) && (s6 < 0)) {
- perror("could not open raw socket");
- exit(1);
- }
- if(s6 >= 0) {
- i = 1;
- if(setsockopt(s6, IPPROTO_IPV6, IPV6_PKTINFO, &i, sizeof(i))) {
- perror("could not set IPV6_PKTINFO sockopt");
- exit(1);
- }
- }
-
- if(daemonize)
- daemon(0, 0);
-
- openlog("icmpdnd", LOG_PID | LOG_NDELAY, LOG_DAEMON);
-
- alive = 1;
- lasterr = 0;
- while(alive) {
- n = 0;
- if(s4 >= 0) {
- pfd[n].fd = s4;
- pfd[n].events = POLLIN;
- n++;
- }
- if(s6 >= 0) {
- pfd[n].fd = s6;
- pfd[n].events = POLLIN;
- n++;
- }
- ret = poll(pfd, n, -1);
-
- curtime = time(NULL);
- if(ret < 0) {
- if(errno == EINTR)
- continue;
- syslog(LOG_ERR, "error while polling sockets: %m");
- if(lasterr == curtime) {
- syslog(LOG_CRIT, "exiting due to repeated errors");
- exit(1);
- }
- lasterr = curtime;
- }
-
- for(i = 0; i < n; i++) {
- if((pfd[i].revents & POLLIN) == 0)
- continue;
- cs = pfd[i].fd;
- memset(&name, 0, sizeof(name));
-
- iov.iov_len = sizeof(buf);
- iov.iov_base = buf;
- mhdr.msg_name = &name;
- mhdr.msg_namelen = sizeof(name);
- mhdr.msg_iov = &iov;
- mhdr.msg_iovlen = 1;
- mhdr.msg_control = cmsgbuf;
- mhdr.msg_controllen = sizeof(cmsgbuf);
-
- ret = recvmsg(cs, &mhdr, 0);
- if(ret < 0) {
- syslog(LOG_WARNING, "error while receiving datagram: %m");
- continue;
- }
-
- if(cs == s4) {
- if(ret < sizeof(iphdr) + sizeof(req))
- continue;
- hdrlen = sizeof(iphdr);
- memcpy(&iphdr, buf, sizeof(iphdr));
- if(iphdr.protocol != IPPROTO_ICMP)
- continue;
- mhdr.msg_control = NULL;
- mhdr.msg_controllen = 0;
- } else if(cs == s6) {
- if(ret < sizeof(req))
- continue;
- ((struct sockaddr_in6 *)&name)->sin6_port = 0;
- hdrlen = 0;
- /* Just keep mhdr.msg_control. */
- } else {
- syslog(LOG_CRIT, "strangeness!");
- abort();
- }
- memcpy(&req, buf + hdrlen, sizeof(req));
- if(req.type != ICMP_NAMEREQ)
- continue;
- rep.type = ICMP_NAMEREP;
- rep.code = 0;
- rep.id = req.id;
- rep.seq = req.seq;
- rep.ttl = htonl(ttl);
- memcpy(buf, &rep, sizeof(rep));
- datalen = filldn(buf + sizeof(rep));
-
- cksum(buf, datalen + sizeof(rep));
-
- iov.iov_len = sizeof(rep) + datalen;
- iov.iov_base = buf;
- mhdr.msg_iov = &iov;
- mhdr.msg_iovlen = 1;
- ret = sendmsg(cs, &mhdr, 0);
- if(ret < 0)
- syslog(LOG_WARNING, "error in sending reply: %m");
- }
- }
-
- close(s4);
- close(s6);
- return(0);
-}
-
-/*
- * Local Variables:
- * compile-command: "gcc -Wall -g -o icmpdnd icmpdnd.c"
- * End:
- */
Dolda2000 GitWeb / icmp-dn.git / blobdiff