From abd276ed9e7ca868616954b41f67a0b99a67a4c3 Mon Sep 17 00:00:00 2001
From: Michael Scherer <misc@zarb.org>
Date: Mon, 23 Dec 2013 21:58:28 +0100
Subject: [PATCH] Add idle option, so we can stop iodine and start it on demand
 with systemd

---
 man/iodine.8  |  6 ++++++
 src/iodined.c | 30 ++++++++++++++++++++++++------
 2 files changed, 30 insertions(+), 6 deletions(-)

diff --git a/man/iodine.8 b/man/iodine.8
index f551399..349ba6f 100644
--- a/man/iodine.8
+++ b/man/iodine.8
@@ -71,6 +71,8 @@ iodine, iodined \- tunnel IPv4 over DNS
 .I context
 .B ] [-F
 .I pidfile
+.B ] [-i
+.I max_idle_time
 .B ]
 .I tunnel_ip
 .B [
@@ -278,6 +280,10 @@ same as 'port'.
 .B Note:
 The forwarding is not fully transparent, and not advised for use
 in production environments.
+.TP
+.B -i max_idle_time
+Make the server stop itself after max_idle_time seconds if no traffic have been received.
+This should be combined with systemd or upstart on demand activation for being effective.
 .SS Client Arguments:
 .TP
 .B nameserver
diff --git a/src/iodined.c b/src/iodined.c
index 6dfa34d..8dc37e1 100644
--- a/src/iodined.c
+++ b/src/iodined.c
@@ -1688,12 +1688,13 @@ tunnel_dns(int tun_fd, int dns_fd, int bind_fd)
 }
 
 static int
-tunnel(int tun_fd, int dns_fd, int bind_fd)
+tunnel(int tun_fd, int dns_fd, int bind_fd, int max_idle_time)
 {
 	struct timeval tv;
 	fd_set fds;
 	int i;
 	int userid;
+	time_t last_action = time(NULL);
 
 	while (running) {
 		int maxfd;
@@ -1744,8 +1745,20 @@ tunnel(int tun_fd, int dns_fd, int bind_fd)
 			return 1;
 		}
 
- 		if (i==0) {	
-			/* timeout; whatever; doesn't matter anymore */
+		if (i==0) {
+			if (max_idle_time) {
+				/* only trigger the check if that's worth ( ie, no need to loop over if there
+				is something to send */
+				if (last_action + max_idle_time < time(NULL)) {
+					for (userid = 0; userid < created_users; userid++) {
+						last_action = ( users[userid].last_pkt > last_action ) ? users[userid].last_pkt : last_action;
+					}
+					if (last_action + max_idle_time < time(NULL)) {
+						fprintf(stderr, "Idling since too long, shutting down...\n");
+						running = 0;
+					}
+				}
+			}
  		} else {
  			if (FD_ISSET(tun_fd, &fds)) {
  				tunnel_tun(tun_fd, dns_fd);
@@ -2172,7 +2185,7 @@ usage() {
 	fprintf(stderr, "Usage: %s [-v] [-h] [-c] [-s] [-f] [-D] [-u user] "
 		"[-t chrootdir] [-d device] [-m mtu] [-z context] "
 		"[-l ip address to listen on] [-p port] [-n external ip] "
-		"[-b dnsport] [-P password] [-F pidfile] "
+		"[-b dnsport] [-P password] [-F pidfile] [-i max idle time] "
 		"tunnel_ip[/netmask] topdomain\n", __progname);
 	exit(2);
 }
@@ -2206,6 +2219,7 @@ help() {
 	fprintf(stderr, "  -b port to forward normal DNS queries to (on localhost)\n");
 	fprintf(stderr, "  -P password used for authentication (max 32 chars will be used)\n");
 	fprintf(stderr, "  -F pidfile to write pid to a file\n");
+	fprintf(stderr, "  -i maximum idle time before shutting down\n");
 	fprintf(stderr, "tunnel_ip is the IP number of the local tunnel interface.\n");
 	fprintf(stderr, "   /netmask sets the size of the tunnel network.\n");
 	fprintf(stderr, "topdomain is the FQDN that is delegated to this server.\n");
@@ -2250,6 +2264,7 @@ main(int argc, char **argv)
 	char *netsize;
 	int ns_get_externalip;
 	int retval;
+	int max_idle_time = 0;
 #ifdef HAVE_SYSTEMD
 	int nb_fds;
 #endif
@@ -2299,7 +2314,7 @@ main(int argc, char **argv)
 	srand(time(NULL));
 	fw_query_init();
 	
-	while ((choice = getopt(argc, argv, "vcsfhDu:t:d:m:l:p:n:b:P:z:F:")) != -1) {
+	while ((choice = getopt(argc, argv, "vcsfhDu:t:d:m:l:p:n:b:P:z:F:i:")) != -1) {
 		switch(choice) {
 		case 'v':
 			version();
@@ -2351,6 +2366,9 @@ main(int argc, char **argv)
 		case 'F':
 			pidfile = optarg;
 			break;    
+		case 'i':
+			max_idle_time = atoi(optarg);
+			break;
 		case 'P':
 			strncpy(password, optarg, sizeof(password));
 			password[sizeof(password)-1] = 0;
@@ -2559,7 +2577,7 @@ main(int argc, char **argv)
 
 	syslog(LOG_INFO, "started, listening on port %d", port);
 	
-	tunnel(tun_fd, dnsd_fd, bind_fd);
+	tunnel(tun_fd, dnsd_fd, bind_fd, max_idle_time);
 
 	syslog(LOG_INFO, "stopping");
 cleanup3: