/*
* icmpdnd - ICMP Domain Name responder daemon for Linux
- * Copyright (C) 2004 Fredrik Tolf <fredrik@dolda2000.com>
+ * 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
#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>
#define ICMP_NAMEREQ 37
#define ICMP_NAMEREP 38
-#define TTL 3600
-
volatile int alive;
size_t filldn(char *dst)
int main(int argc, char **argv)
{
- int ret;
- int s, namelen, datalen;
+ int i, n, ret;
+ int c, cs, s4, s6, datalen;
+ int daemonize, ttl;
unsigned char buf[65536];
- struct sockaddr_in name;
+ struct sockaddr_storage name;
struct reqhdr req;
struct rephdr rep;
struct iphdr iphdr;
-
- if((s = socket(PF_INET, SOCK_RAW, IPPROTO_ICMP)) < 0) {
- perror("could not create raw socket");
+ 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) {
- namelen = sizeof(name);
- ret = recvfrom(s, buf, sizeof(buf), 0, (struct sockaddr *)&name, &namelen);
+ 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;
- perror("recvfrom");
- exit(1);
+ syslog(LOG_ERR, "error while polling sockets: %m");
+ if(lasterr == curtime) {
+ syslog(LOG_CRIT, "exiting due to repeated errors");
+ exit(1);
+ }
+ lasterr = curtime;
}
- if(ret < sizeof(iphdr))
- continue;
- memcpy(&iphdr, buf, sizeof(iphdr));
- if(iphdr.protocol != IPPROTO_ICMP)
- continue;
- if(ret < sizeof(iphdr) + sizeof(req))
- continue;
- memcpy(&req, buf + sizeof(iphdr), 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));
-
- ret = sendto(s, buf, datalen + sizeof(rep), 0, (struct sockaddr *)&name, namelen);
- if(ret < 0) {
- perror("sendto");
- exit(1);
+
+ 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(s);
+ close(s4);
+ close(s6);
return(0);
}
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