bridge: make learning and unicast-flood configurable per bridge port

Tuning these two options allows a more fine grained configuration of the
forwarding database (fdb) of a bridge.

The former allows to enable or disable the learning of the presence of
MAC addresses behind a bridge port. (default: enabled on all ports)

The latter allows to tune the behaviour in case a destination MAC address
of a frame is unknown to the fdb, like only flooding on specific ports or
not flooding on any port. (default: flood on all ports, except incoming)

This can be useful to create a dumb hub, for instance for monitoring
purposes. Or in larger layer 2 mesh networks to avoid keeping redundant
databases (e.g. with the batman-adv translation table).

Signed-off-by: Linus Lüssing <linus.luessing@c0d3.blue>

1 files changed, 18 insertions, 0 deletions

diff --git a/system-linux.c b/system-linux.c
index 351a994..621f99b 100644
--- a/system-linux.c
+++ b/system-linux.c
@@ -372,6 +372,16 @@ static void system_bridge_set_startup_query_interval(struct device *dev, const c
 			      dev->ifname, val);
 }
 
+static void system_bridge_set_learning(struct device *dev, const char *val)
+{
+	system_set_dev_sysctl("/sys/class/net/%s/brport/learning", dev->ifname, val);
+}
+
+static void system_bridge_set_unicast_flood(struct device *dev, const char *val)
+{
+	system_set_dev_sysctl("/sys/class/net/%s/brport/unicast_flood", dev->ifname, val);
+}
+
 static int system_get_sysctl(const char *path, char *buf, const size_t buf_sz)
 {
 	int fd = -1, ret = -1;
@@ -648,6 +658,14 @@ int system_bridge_addif(struct device *bridge, struct device *dev)
 		system_bridge_set_multicast_router(dev, buf, false);
 	}
 
+	if (dev->settings.flags & DEV_OPT_LEARNING &&
+	    !dev->settings.learning)
+		system_bridge_set_learning(dev, "0");
+
+	if (dev->settings.flags & DEV_OPT_UNICAST_FLOOD &&
+	    !dev->settings.unicast_flood)
+		system_bridge_set_unicast_flood(dev, "0");
+
 	return ret;
 }