3 files changed, 26 insertions, 6 deletions

diff --git a/src/ot_config.c b/src/ot_config.c
index 95136b5..6b51c61 100644
--- a/src/ot_config.c
+++ b/src/ot_config.c
@@ -208,6 +208,7 @@ typedef enum {
     CONFIG_TRACKER_REDIRECT_URL,
     CONFIG_LIVESYNC_CLUSTER_NODE_IP,
     CONFIG_LIVESYNC_CLUSTER_LISTEN,
+    CONFIG_LIVESYNC_CLUSTER_GROUP,
 } config_kind;
 
 typedef struct {
@@ -247,6 +248,7 @@ static const config_key config_keys[] = {
 #ifdef WANT_SYNC_LIVE
     CONFIG_KEY("livesync.cluster.node_ip", CONFIG_LIVESYNC_CLUSTER_NODE_IP),
     CONFIG_KEY("livesync.cluster.listen",  CONFIG_LIVESYNC_CLUSTER_LISTEN),
+    CONFIG_KEY("livesync.cluster.group",   CONFIG_LIVESYNC_CLUSTER_GROUP),
 #endif
 };
 static const size_t config_entry_count = sizeof(config_keys) / sizeof(config_keys[0]);
@@ -318,7 +320,7 @@ static int parse_configfile(char *config_filename) {
         int off     = scan_ip6_port(p, tmpip, &tmpport);
 
         if (!off || !listen_scan_options(p + off, &shared, &workers))
-          goto parse_error;
+          exerr("listen.tcp, listen.udp and listen.tcp_udp want an address, optionally a port and options.");
         if (kind != CONFIG_LISTEN_UDP)
           listen_append(tmpip, tmpport, FLAG_TCP, shared, workers), ++bound;
         if (kind != CONFIG_LISTEN_TCP)
@@ -378,6 +380,10 @@ static int parse_configfile(char *config_filename) {
         set_config_option(&g_redirecturl, p);
         break;
 #ifdef WANT_SYNC_LIVE
+      case CONFIG_LIVESYNC_CLUSTER_GROUP:
+        if (!ip_parse(p, tmpip) || livesync_set_group(tmpip) == -1)
+          exerr("livesync.cluster.group wants a multicast address, out of 224.0.0.0/4.");
+        break;
       case CONFIG_LIVESYNC_CLUSTER_NODE_IP:
         if (!scan_ip6_net(p, &tmpnet))
           goto parse_error;
@@ -440,7 +446,7 @@ static void help(char *name) {
   fprintf(stderr, "\nExample:   ./opentracker -i 127.0.0.1 -p 6969 -P 6969 -f ./opentracker.conf -i 10.1.1.23 -p 2710 -p 80\n");
   fprintf(stderr, "           Here -i 127.0.0.1 selects the ip address for the next -p 6969 and -P 6969.\n");
   fprintf(stderr, "           If no port is bound from config file or command line, the last address given\n");
-  fprintf(stderr, "           (or ::1 if none is set) will be used on port 6969.\n");
+  fprintf(stderr, "           is used on port 6969, and every interface if none was given.\n");
 }
 #undef HELPLINE
 
diff --git a/src/ot_livesync.c b/src/ot_livesync.c
index 11b75d2..85577f7 100644
--- a/src/ot_livesync.c
+++ b/src/ot_livesync.c
@@ -22,8 +22,10 @@
 
 #ifdef WANT_SYNC_LIVE
 
-ot_ip6 groupip_1 = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0xff, 0xff, 224, 0, 23, 5};
-static uint16_t g_port = LIVESYNC_PORT;
+/* The multicast group, legacy opentrackers joined by default 224.0.23.5, so it
+   stays the default */
+static ot_ip6   g_group = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0xff, 0xff, 224, 0, 23, 5};
+static uint16_t g_port  = LIVESYNC_PORT;
 
 #define LIVESYNC_INCOMING_BUFFSIZE        (256 * 256)
 
@@ -96,6 +98,14 @@ void livesync_deinit(void) {
     close(g_socket_out);
 }
 
+int livesync_set_group(const ot_ip6 group) {
+  /* v4 multicast is 224.0.0.0/4, and the socket layer has nothing else */
+  if (!ip_is_v4mapped(group) || (group[12] & 0xf0) != 0xe0)
+    return -1;
+  memcpy(g_group, group, sizeof(ot_ip6));
+  return 0;
+}
+
 void livesync_bind_mcast(ot_ip6 ip, uint16_t port) {
   if (!ip_is_v4mapped(ip))
     exerr("v6 mcast support not yet available.");
@@ -105,7 +115,7 @@ void livesync_bind_mcast(ot_ip6 ip, uint16_t port) {
 
   g_port = port;
 
-  if ((g_socket_in = socket_mcast_join(groupip_1, ip, port)) == -1)
+  if ((g_socket_in = socket_mcast_join(g_group, ip, port)) == -1)
     exerr("Error: Cant bind live sync incoming socket.");
 
   if ((g_socket_out = socket_mcast_bind(ip, port, 0)) == -1)
@@ -125,7 +135,7 @@ static void livesync_issue_peersync(sync_buffer *buf) {
      has modified the protected element */
   pthread_mutex_unlock(&g_outbuf_mutex);
 
-  socket_mcast_send(g_socket_out, mycopy, fill, groupip_1, g_port);
+  socket_mcast_send(g_socket_out, mycopy, fill, g_group, g_port);
 }
 
 static void livesync_handle_peersync(struct ot_workstruct *ws, size_t peer_size) {
diff --git a/src/ot_livesync.h b/src/ot_livesync.h
index d8d20b3..cf3c64c 100644
--- a/src/ot_livesync.h
+++ b/src/ot_livesync.h
@@ -48,6 +48,10 @@
 void livesync_init(void);
 void livesync_deinit(void);
 
+/* The group to join and to send to, (defaults to 224.0.23.5).
+   Returns -1 if group is not a v4 multicast address. */
+int  livesync_set_group(const ot_ip6 group);
+
 /* Join multicast group for listening and create sending socket */
 void livesync_bind_mcast(ot_ip6 ip, uint16_t port);