First should-be-working version.

git-svn-id: svn+ssh://svn.dolda2000.com/srv/svn/repos/src/icmp-dn@213 959494ce-11ee-0310-bf91-de5d638817bd

diff --git a/icmpdnd.c b/icmpdnd.c
index 0169e6d..3fa1792 100644 (file)
--- a/icmpdnd.c
+++ b/icmpdnd.c
@@ -1,6 +1,6 @@
 /*
  *  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
@@ -21,6 +21,7 @@
 #include <stdio.h>
 #include <string.h>
 #include <errno.h>
+#include <syslog.h>
 #include <sys/socket.h>
 #include <netinet/in.h>
 #include <arpa/inet.h>
@@ -53,8 +54,6 @@ struct rephdr {
 #define ICMP_NAMEREQ 37
 #define ICMP_NAMEREP 38
 
-#define TTL 3600
-
 volatile int alive;
 
 size_t filldn(char *dst)
@@ -131,18 +130,43 @@ void cksum(void *hdr, size_t len)
 int main(int argc, char **argv)
 {
     int ret;
-    int s, namelen, datalen;
+    int c, s, namelen, datalen;
+    int daemonize, ttl;
     unsigned char buf[65536];
     struct sockaddr_in name;
     struct reqhdr req;
     struct rephdr rep;
     struct iphdr iphdr;
-
+    
+    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);
+       }
+    }
+    
     if((s = socket(PF_INET, SOCK_RAW, IPPROTO_ICMP)) < 0) {
        perror("could not create raw socket");
        exit(1);
     }
     
+    if(daemonize)
+       daemon(0, 0);
+    
+    openlog("icmpdnd", LOG_PID, LOG_DAEMON);
+    
     alive = 1;
     while(alive) {
        namelen = sizeof(name);
@@ -150,32 +174,32 @@ int main(int argc, char **argv)
        if(ret < 0) {
            if(errno == EINTR)
                continue;
-           perror("recvfrom");
+           syslog(LOG_ERR, "error in receiving datagram: %m");
            exit(1);
        }
-       if(ret < sizeof(iphdr))
+       if(ret < sizeof(iphdr) + sizeof(req))
            continue;
        memcpy(&iphdr, buf, sizeof(iphdr));
+       memcpy(&req, buf + sizeof(iphdr), sizeof(req));
        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);
+       rep.ttl = htonl(ttl);
        memcpy(buf, &rep, sizeof(rep));
        datalen = filldn(buf + sizeof(rep));
-
+       
        cksum(buf, datalen + sizeof(rep));
-
+       
+       /* XXX: The correct source address needs to be filled in from
+        * the request's destination address. */
        ret = sendto(s, buf, datalen + sizeof(rep), 0, (struct sockaddr *)&name, namelen);
        if(ret < 0) {
-           perror("sendto");
+           syslog(LOG_WARNING, "error in sending reply: %m");
            exit(1);
        }
     }