Allow setting netmask in iodined, fixes #27. The same netmask will be given to clients as well. Updated docs.

CHANGELOG

@@ -17,6 +17,11 @@ CHANGES:
 	- Upstream data is now Base64 encoded if relay server preserves case and
 		supports the plus (+) character in domain names, fixes #16.
 	- Fixed problem in client when DNS trans. ID has highest bit set (#37)
+	- IP addresses are now assigned within the netmask, so iodined can
+		use any address for itself, fixes #28.
+	- Netmask size is now adjustable. Setting a small net will reduce the
+		number of users. Use x.x.x.x/n notation on iodined tunnel ip.
+		This fixes #27.
 
 2008-08-06: 0.4.2 "Opened Zone"
 	- Applied a few small patches from Maxim Bourmistrov and Gregor Herrmann

doc/proto_00000403.txt

@@ -26,7 +26,7 @@ Client sends:
 	CMC
 Server replies:
 	LNAK means not accepted
-	x.x.x.x-y.y.y.y-mtu means accepted (server ip, client ip, mtu)
+	x.x.x.x-y.y.y.y-mtu-netmask means accepted (server ip, client ip, mtu, netmask bits)
 
 Case check:
 Client sends: 

man/iodine.8

@@ -45,6 +45,9 @@ iodine, iodined \- tunnel IPv4 over DNS
 .I password
 .B ] 
 .I tunnel_ip
+.B [
+.I /netmask
+.B ]
 .I topdomain
 .SH DESCRIPTION
 .B iodine
@@ -133,10 +136,12 @@ is the iodined server, then the topdomain can be chosen freely. This argument
 must be the same on both the client and the server.
 .SS Server Arguments:
 .TP
-.B tunnel_ip
+.B tunnel_ip[/netmask]
 This is the servers ip address on the tunnel interface. The client will be
 given the next ip number in the range. It is recommended to use the 
-10.0.0.0/8 or 172.16.0.0/12 ranges.
+10.0.0.0 or 172.16.0.0 ranges. The default netmask is /27, can be overriden
+by specifying it here. Using a smaller network will limit the number of
+concurrent users.
 .TP
 .B topdomain
 The dns traffic will is expected to be sent as querys of type NULL for 

src/iodine.c

@@ -488,15 +488,16 @@ perform_login:
 			}
 
 			if (read > 0) {
+				int netmask;
 				if (strncmp("LNAK", in, 4) == 0) {
 					printf("Bad password\n");
 					return 1;
-				} else if (sscanf(in, "%64[^-]-%64[^-]-%d", 
+				} else if (sscanf(in, "%64[^-]-%64[^-]-%d-%d", 
-					server, client, &mtu) == 3) {
+					server, client, &mtu, &netmask) == 4) {
 					
 					server[64] = 0;
 					client[64] = 0;
-					if (tun_setip(client) == 0 && 
+					if (tun_setip(client, netmask) == 0 && 
 						tun_setmtu(mtu) == 0) {
 						goto perform_case_check;
 					} else {

src/iodined.c

@@ -56,10 +56,12 @@ static int running = 1;
 static char *topdomain;
 static char password[33];
 static struct encoder *b32;
+static int created_users;
 
 static int check_ip;
 static int my_mtu;
 static in_addr_t my_ip;
+static int netmask;
 
 static in_addr_t ns_ip;
 
@@ -230,7 +232,7 @@ handle_null_request(int tun_fd, int dns_fd, struct query *q, int domain_len)
 				users[userid].q.id = 0;
 			} else {
 				/* No space for another user */
-				send_version_response(dns_fd, VERSION_FULL, USERS, 0, q);
+				send_version_response(dns_fd, VERSION_FULL, created_users, 0, q);
 			}
 		} else {
 			send_version_response(dns_fd, VERSION_NACK, VERSION, 0, q);
@@ -251,15 +253,15 @@ handle_null_request(int tun_fd, int dns_fd, struct query *q, int domain_len)
 			write_dns(dns_fd, q, "BADIP", 5);
 		} else {
 			if (read >= 18 && (memcmp(logindata, unpacked+1, 16) == 0)) {
-				/* Login ok, send ip/mtu info */
+				/* Login ok, send ip/mtu/netmask info */
 
 				tempip.s_addr = my_ip;
 				tmp[0] = strdup(inet_ntoa(tempip));
 				tempip.s_addr = users[userid].tun_ip;
 				tmp[1] = strdup(inet_ntoa(tempip));
 
-				read = snprintf(out, sizeof(out), "%s-%s-%d", 
+				read = snprintf(out, sizeof(out), "%s-%s-%d-%d", 
-						tmp[0], tmp[1], my_mtu);
+						tmp[0], tmp[1], my_mtu, netmask);
 
 				write_dns(dns_fd, q, out, read);
 				q->id = 0;
@@ -726,7 +728,7 @@ usage() {
 	printf("Usage: %s [-v] [-h] [-c] [-s] [-f] [-D] [-u user] "
 		"[-t chrootdir] [-d device] [-m mtu] "
 		"[-l ip address to listen on] [-p port] [-n external ip] [-b dnsport] [-P password]"
-		" tunnel_ip topdomain\n", __progname);
+		" tunnel_ip[/netmask] topdomain\n", __progname);
 	exit(2);
 }
 
@@ -738,7 +740,7 @@ help() {
 	printf("Usage: %s [-v] [-h] [-c] [-s] [-f] [-D] [-u user] "
 		"[-t chrootdir] [-d device] [-m mtu] "
 		"[-l ip address to listen on] [-p port] [-n external ip] [-b dnsport] [-P password]"
-		" tunnel_ip topdomain\n", __progname);
+		" tunnel_ip[/netmask] topdomain\n", __progname);
 	printf("  -v to print version info and exit\n");
 	printf("  -h to print this help and exit\n");
 	printf("  -c to disable check of client IP/port on each request\n");
@@ -757,6 +759,7 @@ help() {
 	printf("  -b port to forward normal DNS queries to (on localhost)\n");
 	printf("  -P password used for authentication (max 32 chars will be used)\n");
 	printf("tunnel_ip is the IP number of the local tunnel interface.\n");
+	printf("   /netmask sets the size of the tunnel network.\n");
 	printf("topdomain is the FQDN that is delegated to this server.\n");
 	exit(0);
 }
@@ -791,8 +794,7 @@ main(int argc, char **argv)
 	int port;
 	int mtu;
 	int skipipconfig;
-	int netmask;
+	char *netsize;
-	int created_users;
 
 	username = NULL;
 	newroot = NULL;
@@ -892,6 +894,13 @@ main(int argc, char **argv)
 	if (argc != 2) 
 		usage();
 	
+	netsize = strchr(argv[0], '/');
+	if (netsize) {
+		*netsize = 0;
+		netsize++;
+		netmask = atoi(netsize);
+	}
+
 	my_ip = inet_addr(argv[0]);
 	
 	if (my_ip == INADDR_NONE) {
@@ -968,7 +977,7 @@ main(int argc, char **argv)
 	if ((tun_fd = open_tun(device)) == -1)
 		goto cleanup0;
 	if (!skipipconfig)
-		if (tun_setip(argv[0]) != 0 || tun_setmtu(mtu) != 0)
+		if (tun_setip(argv[0], netmask) != 0 || tun_setmtu(mtu) != 0)
 			goto cleanup1;
 	if ((dnsd_fd = open_dns(port, listen_ip)) == -1) 
 		goto cleanup2;

src/tun.c

@@ -181,19 +181,30 @@ read_tun(int tun_fd, char *buf, size_t len)
 }
 
 int
-tun_setip(const char *ip)
+tun_setip(const char *ip, int netbits)
 {
 	char cmdline[512];
+	int netmask;
+	struct in_addr net;
+	int i;
+
 #ifndef LINUX
 	int r;
 #endif
+	netmask = 0;
+	for (i = 0; i < netbits; i++) {
+		netmask = (netmask << 1) | 1;
+	}
+	netmask <<= (32 - netbits);
+	net.s_addr = htonl(netmask);
 
 	if (inet_addr(ip) != INADDR_NONE) {
 		snprintf(cmdline, sizeof(cmdline), 
-				"/sbin/ifconfig %s %s %s netmask 255.255.255.0",
+				"/sbin/ifconfig %s %s %s netmask %s",
 				if_name,
 				ip,
-				ip);
+				ip,
+				inet_ntoa(net));
 		
 		printf("Setting IP of %s to %s\n", if_name, ip);
 #ifndef LINUX
@@ -202,10 +213,10 @@ tun_setip(const char *ip)
 			return r;
 		} else {
 			snprintf(cmdline, sizeof(cmdline),
-					"/sbin/route add %s/24 %s",
+					"/sbin/route add %s/%d %s",
-					ip, ip);
+					ip, netbits, ip);
 		}
-		printf("Adding route %s/24 to %s\n", ip, ip);
+		printf("Adding route %s/%d to %s\n", ip, netbits, ip);
 #endif
 		return system(cmdline);
 	} else {

src/tun.h

@@ -21,7 +21,7 @@ int open_tun(const char *);
 void close_tun(int);
 int write_tun(int, char *, size_t);
 ssize_t read_tun(int, char *, size_t);
-int tun_setip(const char *);
+int tun_setip(const char *, int);
 int tun_setmtu(const size_t);
 
 #endif /* _TUN_H_ */