From 4c0032c04c3724c19c21cbea654cc4b84845f6a2 Mon Sep 17 00:00:00 2001
From: Erik Ekman <yarrick@kryo.se>
Date: Fri, 11 Aug 2006 22:52:36 +0000
Subject: [PATCH] Added support for choosing ip to listen on for DNS

---
 dns.c     |  6 +++---
 dns.h     |  2 +-
 iodine.c  |  2 +-
 iodined.c | 19 +++++++++++++++----
 4 files changed, 20 insertions(+), 9 deletions(-)

diff --git a/dns.c b/dns.c
index 2cf04ab..035a89c 100644
--- a/dns.c
+++ b/dns.c
@@ -58,7 +58,7 @@ uint16_t pingid;
 
 
 int 
-open_dns(const char *domain, int localport) 
+open_dns(const char *domain, int localport, in_addr_t listen_ip) 
 {
 	int fd;
 	int flag;
@@ -67,9 +67,9 @@ open_dns(const char *domain, int localport)
 	bzero(&addr, sizeof(addr));
 	addr.sin_family = AF_INET;
 	addr.sin_port = htons(localport);
-	addr.sin_addr.s_addr = htonl(INADDR_ANY);
+	addr.sin_addr.s_addr = listen_ip; // This is already network byte order, inet_addr() or constant INADDR_ANY (==0)
 
-	fd = socket(AF_INET, SOCK_DGRAM, 0);
+	fd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
 	if(fd < 0) {
 		warn("socket");
 		return -1;
diff --git a/dns.h b/dns.h
index ad27b6b..62f6ca1 100644
--- a/dns.h
+++ b/dns.h
@@ -17,7 +17,7 @@
 #ifndef _DNS_H_
 #define _DNS_H_
 
-int open_dns(const char *, int);
+int open_dns(const char *, int, in_addr_t);
 int dns_settarget(const char*);
 void close_dns(int);
 
diff --git a/iodine.c b/iodine.c
index 8944bfc..f5752a0 100644
--- a/iodine.c
+++ b/iodine.c
@@ -255,7 +255,7 @@ main(int argc, char **argv)
 
 	if ((tun_fd = open_tun(device)) == -1)
 		goto cleanup1;
-	if ((dns_fd = open_dns(argv[1], 0)) == -1)
+	if ((dns_fd = open_dns(argv[1], 0, INADDR_ANY)) == -1)
 		goto cleanup2;
 	if (dns_settarget(argv[0]) == -1)
 		goto cleanup2;
diff --git a/iodined.c b/iodined.c
index 6d0a347..74ecee8 100644
--- a/iodined.c
+++ b/iodined.c
@@ -163,7 +163,7 @@ extern char *__progname;
 
 static void
 usage() {
-	printf("Usage: %s [-v] [-h] [-f] [-u user] [-t chrootdir] [-d device] [-m mtu] "
+	printf("Usage: %s [-v] [-h] [-f] [-u user] [-t chrootdir] [-d device] [-m mtu] [-l ip address to listen on] "
 			"tunnel_ip topdomain\n", __progname);
 	exit(2);
 }
@@ -171,7 +171,7 @@ usage() {
 static void
 help() {
 	printf("iodine IP over DNS tunneling server\n");
-	printf("Usage: %s [-v] [-h] [-f] [-u user] [-t chrootdir] [-d device] [-m mtu] "
+	printf("Usage: %s [-v] [-h] [-f] [-u user] [-t chrootdir] [-d device] [-m mtu] [-l ip address to listen on] "
 		   "tunnel_ip topdomain\n", __progname);
 	printf("  -v to print version info and exit\n");
 	printf("  -h to print this help and exit\n");
@@ -180,6 +180,7 @@ help() {
 	printf("  -t dir to chroot to directory dir\n");
 	printf("  -d device to set tunnel device name\n");
 	printf("  -m mtu to set tunnel device mtu\n");
+	printf("  -l ip address to listen on for incoming dns traffic (default 0.0.0.0)\n");
 	printf("tunnel_ip is the IP number of the local tunnel interface.\n");
 	printf("topdomain is the FQDN that is delegated to this server.\n");
 	exit(0);
@@ -205,19 +206,21 @@ main(int argc, char **argv)
 	int foreground;
 	int mtu;
 	struct passwd *pw;
+	in_addr_t listen_ip;
 
 	username = NULL;
 	newroot = NULL;
 	device = NULL;
 	foreground = 0;
 	mtu = 1024;
+	listen_ip = INADDR_ANY;
 
 	packetbuf.len = 0;
 	packetbuf.offset = 0;
 	outpacket.len = 0;
 	q.id = 0;
 	
-	while ((choice = getopt(argc, argv, "vfhu:t:d:m:")) != -1) {
+	while ((choice = getopt(argc, argv, "vfhu:t:d:m:l:")) != -1) {
 		switch(choice) {
 		case 'v':
 			version();
@@ -240,6 +243,9 @@ main(int argc, char **argv)
 		case 'm':
 			mtu = atoi(optarg);
 			break;
+		case 'l':
+			listen_ip = inet_addr(optarg);
+			break;
 		default:
 			usage();
 			break;
@@ -270,11 +276,16 @@ main(int argc, char **argv)
 		usage();
 	}
 
+	if (listen_ip == INADDR_NONE) {
+		printf("Bad IP address to listen on.\n");
+		usage();
+	}
+
 	if ((tun_fd = open_tun(device)) == -1)
 		goto cleanup0;
 	if (tun_setip(argv[0]) != 0 || tun_setmtu(mtu) != 0)
 		goto cleanup1;
-	if ((dnsd_fd = open_dns(argv[1], 53)) == -1) 
+	if ((dnsd_fd = open_dns(argv[1], 53, listen_ip)) == -1) 
 		goto cleanup2;
 
 	my_ip = inet_addr(argv[0]);