batman-adv: tvlv - basic infrastructure

The goal is to provide the infrastructure for sending, receiving and
parsing information 'containers' while preserving backward
compatibility. TVLV (based on the commonly known Type Length Value
technique) was chosen as the format for those containers. Even if a
node does not know the tvlv type of a certain container it can simply
skip the current container and proceed with the next. Past experience
has shown features evolve over time, so a 'version' field was added
right from the start to allow differentiating between feature
variants - hence the name: T(ype) V(ersion) L(ength) V(alue).

This patch introduces the basic TVLV infrastructure:
 * register / unregister tvlv containers to be sent with each OGM
   (on primary interfaces only)
 * register / unregister callback handlers to be called upon
   finding the corresponding tvlv type in a tvlv buffer
 * unicast tvlv send / receive API calls

Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>
Signed-off-by: Spyros Gasteratos <morfeas3000@gmail.com>
Signed-off-by: Antonio Quartulli <antonio@meshcoding.com>

1 files changed, 72 insertions, 0 deletions

diff --git a/net/batman-adv/types.h b/net/batman-adv/types.h
index b2c94e139319..4bdea16bc70c 100644
--- a/net/batman-adv/types.h
+++ b/net/batman-adv/types.h
@@ -430,6 +430,20 @@ struct batadv_priv_gw {
 };
 
 /**
+ * struct batadv_priv_tvlv - per mesh interface tvlv data
+ * @container_list: list of registered tvlv containers to be sent with each OGM
+ * @handler_list: list of the various tvlv content handlers
+ * @container_list_lock: protects tvlv container list access
+ * @handler_list_lock: protects handler list access
+ */
+struct batadv_priv_tvlv {
+	struct hlist_head container_list;
+	struct hlist_head handler_list;
+	spinlock_t container_list_lock; /* protects container_list */
+	spinlock_t handler_list_lock; /* protects handler_list */
+};
+
+/**
  * struct batadv_priv_vis - per mesh interface vis data
  * @send_list: list of batadv_vis_info packets to sent
  * @hash: hash table containing vis data from other nodes in the network
@@ -531,6 +545,7 @@ struct batadv_priv_nc {
  * @debug_log: holding debug logging relevant data
  * @gw: gateway data
  * @tt: translation table data
+ * @tvlv: type-version-length-value data
  * @vis: vis data
  * @dat: distributed arp table data
  * @network_coding: bool indicating whether network coding is enabled
@@ -583,6 +598,7 @@ struct batadv_priv {
 #endif
 	struct batadv_priv_gw gw;
 	struct batadv_priv_tt tt;
+	struct batadv_priv_tvlv tvlv;
 	struct batadv_priv_vis vis;
 #ifdef CONFIG_BATMAN_ADV_DAT
 	struct batadv_priv_dat dat;
@@ -992,4 +1008,60 @@ struct batadv_dat_candidate {
 	struct batadv_orig_node *orig_node;
 };
 
+/**
+ * struct batadv_tvlv_container - container for tvlv appended to OGMs
+ * @list: hlist node for batadv_priv_tvlv::container_list
+ * @tvlv_hdr: tvlv header information needed to construct the tvlv
+ * @value_len: length of the buffer following this struct which contains
+ *  the actual tvlv payload
+ * @refcount: number of contexts the object is used
+ */
+struct batadv_tvlv_container {
+	struct hlist_node list;
+	struct batadv_tvlv_hdr tvlv_hdr;
+	atomic_t refcount;
+};
+
+/**
+ * struct batadv_tvlv_handler - handler for specific tvlv type and version
+ * @list: hlist node for batadv_priv_tvlv::handler_list
+ * @ogm_handler: handler callback which is given the tvlv payload to process on
+ *  incoming OGM packets
+ * @unicast_handler: handler callback which is given the tvlv payload to process
+ *  on incoming unicast tvlv packets
+ * @type: tvlv type this handler feels responsible for
+ * @version: tvlv version this handler feels responsible for
+ * @flags: tvlv handler flags
+ * @refcount: number of contexts the object is used
+ * @rcu: struct used for freeing in an RCU-safe manner
+ */
+struct batadv_tvlv_handler {
+	struct hlist_node list;
+	void (*ogm_handler)(struct batadv_priv *bat_priv,
+			    struct batadv_orig_node *orig,
+			    uint8_t flags,
+			    void *tvlv_value, uint16_t tvlv_value_len);
+	int (*unicast_handler)(struct batadv_priv *bat_priv,
+			       uint8_t *src, uint8_t *dst,
+			       void *tvlv_value, uint16_t tvlv_value_len);
+	uint8_t type;
+	uint8_t version;
+	uint8_t flags;
+	atomic_t refcount;
+	struct rcu_head rcu;
+};
+
+/**
+ * enum batadv_tvlv_handler_flags - tvlv handler flags definitions
+ * @BATADV_TVLV_HANDLER_OGM_CIFNOTFND: tvlv ogm processing function will call
+ *  this handler even if its type was not found (with no data)
+ * @BATADV_TVLV_HANDLER_OGM_CALLED: interval tvlv handling flag - the API marks
+ *  a handler as being called, so it won't be called if the
+ *  BATADV_TVLV_HANDLER_OGM_CIFNOTFND flag was set
+ */
+enum batadv_tvlv_handler_flags {
+	BATADV_TVLV_HANDLER_OGM_CIFNOTFND = BIT(1),
+	BATADV_TVLV_HANDLER_OGM_CALLED = BIT(2),
+};
+
 #endif /* _NET_BATMAN_ADV_TYPES_H_ */