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, 48 insertions, 0 deletions

diff --git a/net/batman-adv/routing.c b/net/batman-adv/routing.c
index 0439395d7ba5..9640656d4e51 100644
--- a/net/batman-adv/routing.c
+++ b/net/batman-adv/routing.c
@@ -1139,6 +1139,54 @@ rx_success:
 	return batadv_route_unicast_packet(skb, recv_if);
 }
 
+/**
+ * batadv_recv_unicast_tvlv - receive and process unicast tvlv packets
+ * @skb: unicast tvlv packet to process
+ * @recv_if: pointer to interface this packet was received on
+ * @dst_addr: the payload destination
+ *
+ * Returns NET_RX_SUCCESS if the packet has been consumed or NET_RX_DROP
+ * otherwise.
+ */
+int batadv_recv_unicast_tvlv(struct sk_buff *skb,
+			     struct batadv_hard_iface *recv_if)
+{
+	struct batadv_priv *bat_priv = netdev_priv(recv_if->soft_iface);
+	struct batadv_unicast_tvlv_packet *unicast_tvlv_packet;
+	unsigned char *tvlv_buff;
+	uint16_t tvlv_buff_len;
+	int hdr_size = sizeof(*unicast_tvlv_packet);
+	int ret = NET_RX_DROP;
+
+	if (batadv_check_unicast_packet(bat_priv, skb, hdr_size) < 0)
+		return NET_RX_DROP;
+
+	/* the header is likely to be modified while forwarding */
+	if (skb_cow(skb, hdr_size) < 0)
+		return NET_RX_DROP;
+
+	/* packet needs to be linearized to access the tvlv content */
+	if (skb_linearize(skb) < 0)
+		return NET_RX_DROP;
+
+	unicast_tvlv_packet = (struct batadv_unicast_tvlv_packet *)skb->data;
+
+	tvlv_buff = (unsigned char *)(skb->data + hdr_size);
+	tvlv_buff_len = ntohs(unicast_tvlv_packet->tvlv_len);
+
+	if (tvlv_buff_len > skb->len - hdr_size)
+		return NET_RX_DROP;
+
+	ret = batadv_tvlv_containers_process(bat_priv, false, NULL,
+					     unicast_tvlv_packet->src,
+					     unicast_tvlv_packet->dst,
+					     tvlv_buff, tvlv_buff_len);
+
+	if (ret != NET_RX_SUCCESS)
+		ret = batadv_route_unicast_packet(skb, recv_if);
+
+	return ret;
+}
 
 int batadv_recv_bcast_packet(struct sk_buff *skb,
 			     struct batadv_hard_iface *recv_if)