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>

3 files changed, 42 insertions, 0 deletions

diff --git a/device.c b/device.c
index 9344e1b..0e07615 100644
--- a/device.c
+++ b/device.c
@@ -51,6 +51,8 @@ static const struct blobmsg_policy dev_attrs[__DEV_ATTR_MAX] = {
 	[DEV_ATTR_MULTICAST_TO_UNICAST] = { .name = "multicast_to_unicast", .type = BLOBMSG_TYPE_BOOL },
 	[DEV_ATTR_MULTICAST_ROUTER] = { .name = "multicast_router", .type = BLOBMSG_TYPE_INT32 },
 	[DEV_ATTR_MULTICAST] = { .name ="multicast", .type = BLOBMSG_TYPE_BOOL },
+	[DEV_ATTR_LEARNING] = { .name ="learning", .type = BLOBMSG_TYPE_BOOL },
+	[DEV_ATTR_UNICAST_FLOOD] = { .name ="unicast_flood", .type = BLOBMSG_TYPE_BOOL },
 };
 
 const struct uci_blob_param_list device_attr_list = {
@@ -177,6 +179,8 @@ device_merge_settings(struct device *dev, struct device_settings *n)
 		s->multicast : os->multicast;
 	n->multicast_to_unicast = s->multicast_to_unicast;
 	n->multicast_router = s->multicast_router;
+	n->learning = s->learning;
+	n->unicast_flood = s->unicast_flood;
 	n->flags = s->flags | os->flags | os->valid_flags;
 }
 
@@ -295,6 +299,16 @@ device_init_settings(struct device *dev, struct blob_attr **tb)
 		s->flags |= DEV_OPT_MULTICAST;
 	}
 
+	if ((cur = tb[DEV_ATTR_LEARNING])) {
+		s->learning = blobmsg_get_bool(cur);
+		s->flags |= DEV_OPT_LEARNING;
+	}
+
+	if ((cur = tb[DEV_ATTR_UNICAST_FLOOD])) {
+		s->unicast_flood = blobmsg_get_bool(cur);
+		s->flags |= DEV_OPT_UNICAST_FLOOD;
+	}
+
 	device_set_disabled(dev, disabled);
 }
 
@@ -939,6 +953,10 @@ device_dump_status(struct blob_buf *b, struct device *dev)
 			blobmsg_add_u32(b, "multicast_router", st.multicast_router);
 		if (st.flags & DEV_OPT_MULTICAST)
 			blobmsg_add_u8(b, "multicast", st.multicast);
+		if (st.flags & DEV_OPT_LEARNING)
+			blobmsg_add_u8(b, "learning", st.learning);
+		if (st.flags & DEV_OPT_UNICAST_FLOOD)
+			blobmsg_add_u8(b, "unicast_flood", st.unicast_flood);
 	}
 
 	s = blobmsg_open_table(b, "statistics");
diff --git a/device.h b/device.h
index ac77cfb..4a88c05 100644
--- a/device.h
+++ b/device.h
@@ -45,6 +45,8 @@ enum {
 	DEV_ATTR_MULTICAST_TO_UNICAST,
 	DEV_ATTR_MULTICAST_ROUTER,
 	DEV_ATTR_MULTICAST,
+	DEV_ATTR_LEARNING,
+	DEV_ATTR_UNICAST_FLOOD,
 	__DEV_ATTR_MAX,
 };
 
@@ -88,6 +90,8 @@ enum {
 	DEV_OPT_MULTICAST_TO_UNICAST	= (1 << 14),
 	DEV_OPT_MULTICAST_ROUTER	= (1 << 15),
 	DEV_OPT_MULTICAST		= (1 << 16),
+	DEV_OPT_LEARNING		= (1 << 17),
+	DEV_OPT_UNICAST_FLOOD		= (1 << 18),
 };
 
 /* events broadcasted to all users of a device */
@@ -149,6 +153,8 @@ struct device_settings {
 	bool multicast_to_unicast;
 	unsigned int multicast_router;
 	bool multicast;
+	bool learning;
+	bool unicast_flood;
 };
 
 /*
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;
 }