batman-adv: Receive fragmented packets and merge

Fragments arriving at their destination are buffered for later merge.
Merged packets are passed to the main receive function as had they never
been fragmented.

Fragments are forwarded without merging if the MTU of the outgoing
interface is smaller than the size of the merged packet.
Signed-off-by: Martin Hundebøll <martin@hundeboll.net>
Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>
Signed-off-by: Antonio Quartulli <antonio@meshcoding.com>

net/batman-adv/Makefile

@@ -24,6 +24,7 @@ batman-adv-y += bitarray.o
 batman-adv-$(CONFIG_BATMAN_ADV_BLA) += bridge_loop_avoidance.o
 batman-adv-y += debugfs.o
 batman-adv-$(CONFIG_BATMAN_ADV_DAT) += distributed-arp-table.o
+batman-adv-y += fragmentation.o
 batman-adv-y += gateway_client.o
 batman-adv-y += gateway_common.o
 batman-adv-y += hard-interface.o

net/batman-adv/fragmentation.h

+/* Copyright (C) 2013 B.A.T.M.A.N. contributors:
+ *
+ * Martin Hundebøll <martin@hundeboll.net>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of version 2 of the GNU General Public
+ * License as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA
+ */
+
+#ifndef _NET_BATMAN_ADV_FRAGMENTATION_H_
+#define _NET_BATMAN_ADV_FRAGMENTATION_H_
+
+void batadv_frag_purge_orig(struct batadv_orig_node *orig,
+			    bool (*check_cb)(struct batadv_frag_table_entry *));
+bool batadv_frag_skb_fwd(struct sk_buff *skb,
+			 struct batadv_hard_iface *recv_if,
+			 struct batadv_orig_node *orig_node_src);
+bool batadv_frag_skb_buffer(struct sk_buff **skb,
+			    struct batadv_orig_node *orig_node);
+
+/**
+ * batadv_frag_check_entry - check if a list of fragments has timed out
+ * @frags_entry: table entry to check
+ *
+ * Returns true if the frags entry has timed out, false otherwise.
+ */
+static inline bool
+batadv_frag_check_entry(struct batadv_frag_table_entry *frags_entry)
+{
+	if (!hlist_empty(&frags_entry->head) &&
+	    batadv_has_timed_out(frags_entry->timestamp, BATADV_FRAG_TIMEOUT))
+		return true;
+	else
+		return false;
+}
+
+#endif /* _NET_BATMAN_ADV_FRAGMENTATION_H_ */

net/batman-adv/main.c

@@ -40,6 +40,7 @@
 #include "hash.h"
 #include "bat_algo.h"
 #include "network-coding.h"
+#include "fragmentation.h"
 
 
 /* List manipulations on hardif_list have to be rtnl_lock()'ed,
@@ -399,6 +400,7 @@ static void batadv_recv_handler_init(void)
 	BUILD_BUG_ON(offsetof(struct batadv_unicast_4addr_packet, src) != 10);
 	BUILD_BUG_ON(offsetof(struct batadv_unicast_packet, dest) != 4);
 	BUILD_BUG_ON(offsetof(struct batadv_unicast_tvlv_packet, dst) != 4);
+	BUILD_BUG_ON(offsetof(struct batadv_frag_packet, dest) != 4);
 	BUILD_BUG_ON(offsetof(struct batadv_icmp_packet, dst) != 4);
 	BUILD_BUG_ON(offsetof(struct batadv_icmp_packet_rr, dst) != 4);
 
@@ -414,6 +416,8 @@ static void batadv_recv_handler_init(void)
 	batadv_rx_handler[BATADV_UNICAST_TVLV] = batadv_recv_unicast_tvlv;
 	/* batman icmp packet */
 	batadv_rx_handler[BATADV_ICMP] = batadv_recv_icmp_packet;
+	/* Fragmented packets */
+	batadv_rx_handler[BATADV_UNICAST_FRAG] = batadv_recv_frag_packet;
 }
 
 int

net/batman-adv/main.h

@@ -131,6 +131,15 @@ enum batadv_uev_type {
 
 #define BATADV_GW_THRESHOLD	50
 
+/* Number of fragment chains for each orig_node */
+#define BATADV_FRAG_BUFFER_COUNT 8
+/* Maximum number of fragments for one packet */
+#define BATADV_FRAG_MAX_FRAGMENTS 16
+/* Maxumim size of each fragment */
+#define BATADV_FRAG_MAX_FRAG_SIZE 1400
+/* Time to keep fragments while waiting for rest of the fragments */
+#define BATADV_FRAG_TIMEOUT 10000
+
 #define BATADV_DAT_CANDIDATE_NOT_FOUND	0
 #define BATADV_DAT_CANDIDATE_ORIG	1
 

net/batman-adv/originator.c

@@ -28,6 +28,7 @@
 #include "soft-interface.h"
 #include "bridge_loop_avoidance.h"
 #include "network-coding.h"
+#include "fragmentation.h"
 
 /* hash class keys */
 static struct lock_class_key batadv_orig_hash_lock_class_key;
@@ -145,6 +146,8 @@ static void batadv_orig_node_free_rcu(struct rcu_head *rcu)
 	/* Free nc_nodes */
 	batadv_nc_purge_orig(orig_node->bat_priv, orig_node, NULL);
 
+	batadv_frag_purge_orig(orig_node, NULL);
+
 	batadv_tt_global_del_orig(orig_node->bat_priv, orig_node,
 				  "originator timed out");
 
@@ -215,7 +218,7 @@ struct batadv_orig_node *batadv_get_orig_node(struct batadv_priv *bat_priv,
 					      const uint8_t *addr)
 {
 	struct batadv_orig_node *orig_node;
-	int size;
+	int size, i;
 	int hash_added;
 	unsigned long reset_time;
 
@@ -267,6 +270,12 @@ struct batadv_orig_node *batadv_get_orig_node(struct batadv_priv *bat_priv,
 	size = bat_priv->num_ifaces * sizeof(uint8_t);
 	orig_node->bcast_own_sum = kzalloc(size, GFP_ATOMIC);
 
+	for (i = 0; i < BATADV_FRAG_BUFFER_COUNT; i++) {
+		INIT_HLIST_HEAD(&orig_node->fragments[i].head);
+		spin_lock_init(&orig_node->fragments[i].lock);
+		orig_node->fragments[i].size = 0;
+	}
+
 	if (!orig_node->bcast_own_sum)
 		goto free_bcast_own;
 
@@ -388,6 +397,9 @@ static void _batadv_purge_orig(struct batadv_priv *bat_priv)
 				batadv_orig_node_free_ref(orig_node);
 				continue;
 			}
+
+			batadv_frag_purge_orig(orig_node,
+					       batadv_frag_check_entry);
 		}
 		spin_unlock_bh(list_lock);
 	}

net/batman-adv/packet.h

@@ -249,6 +249,33 @@ struct batadv_unicast_4addr_packet {
 	 */
 };
 
+/**
+ * struct batadv_frag_packet - fragmented packet
+ * @header: common batman packet header with type, compatversion, and ttl
+ * @dest: final destination used when routing fragments
+ * @orig: originator of the fragment used when merging the packet
+ * @no: fragment number within this sequence
+ * @reserved: reserved byte for alignment
+ * @seqno: sequence identification
+ * @total_size: size of the merged packet
+ */
+struct batadv_frag_packet {
+	struct  batadv_header header;
+#if defined(__BIG_ENDIAN_BITFIELD)
+	uint8_t no:4;
+	uint8_t reserved:4;
+#elif defined(__LITTLE_ENDIAN_BITFIELD)
+	uint8_t reserved:4;
+	uint8_t no:4;
+#else
+#error "unknown bitfield endianess"
+#endif
+	uint8_t dest[ETH_ALEN];
+	uint8_t orig[ETH_ALEN];
+	__be16  seqno;
+	__be16  total_size;
+};
+
 struct batadv_bcast_packet {
 	struct batadv_header header;
 	uint8_t  reserved;

net/batman-adv/routing.c

@@ -28,6 +28,7 @@
 #include "bridge_loop_avoidance.h"
 #include "distributed-arp-table.h"
 #include "network-coding.h"
+#include "fragmentation.h"
 
 static int batadv_route_unicast_packet(struct sk_buff *skb,
 				       struct batadv_hard_iface *recv_if);
@@ -1013,6 +1014,64 @@ int batadv_recv_unicast_tvlv(struct sk_buff *skb,
 	return ret;
 }
 
+/**
+ * batadv_recv_frag_packet - process received fragment
+ * @skb: the received fragment
+ * @recv_if: interface that the skb is received on
+ *
+ * This function does one of the three following things: 1) Forward fragment, if
+ * the assembled packet will exceed our MTU; 2) Buffer fragment, if we till
+ * lack further fragments; 3) Merge fragments, if we have all needed parts.
+ *
+ * Return NET_RX_DROP if the skb is not consumed, NET_RX_SUCCESS otherwise.
+ */
+int batadv_recv_frag_packet(struct sk_buff *skb,
+			    struct batadv_hard_iface *recv_if)
+{
+	struct batadv_priv *bat_priv = netdev_priv(recv_if->soft_iface);
+	struct batadv_orig_node *orig_node_src = NULL;
+	struct batadv_frag_packet *frag_packet;
+	int ret = NET_RX_DROP;
+
+	if (batadv_check_unicast_packet(bat_priv, skb,
+					sizeof(*frag_packet)) < 0)
+		goto out;
+
+	frag_packet = (struct batadv_frag_packet *)skb->data;
+	orig_node_src = batadv_orig_hash_find(bat_priv, frag_packet->orig);
+	if (!orig_node_src)
+		goto out;
+
+	/* Route the fragment if it is not for us and too big to be merged. */
+	if (!batadv_is_my_mac(bat_priv, frag_packet->dest) &&
+	    batadv_frag_skb_fwd(skb, recv_if, orig_node_src)) {
+		ret = NET_RX_SUCCESS;
+		goto out;
+	}
+
+	batadv_inc_counter(bat_priv, BATADV_CNT_FRAG_RX);
+	batadv_add_counter(bat_priv, BATADV_CNT_FRAG_RX_BYTES, skb->len);
+
+	/* Add fragment to buffer and merge if possible. */
+	if (!batadv_frag_skb_buffer(&skb, orig_node_src))
+		goto out;
+
+	/* Deliver merged packet to the appropriate handler, if it was
+	 * merged
+	 */
+	if (skb)
+		batadv_batman_skb_recv(skb, recv_if->net_dev,
+				       &recv_if->batman_adv_ptype, NULL);
+
+	ret = NET_RX_SUCCESS;
+
+out:
+	if (orig_node_src)
+		batadv_orig_node_free_ref(orig_node_src);
+
+	return ret;
+}
+
 int batadv_recv_bcast_packet(struct sk_buff *skb,
 			     struct batadv_hard_iface *recv_if)
 {

net/batman-adv/routing.h

@@ -30,6 +30,8 @@ int batadv_recv_icmp_packet(struct sk_buff *skb,
 			    struct batadv_hard_iface *recv_if);
 int batadv_recv_unicast_packet(struct sk_buff *skb,
 			       struct batadv_hard_iface *recv_if);
+int batadv_recv_frag_packet(struct sk_buff *skb,
+			    struct batadv_hard_iface *iface);
 int batadv_recv_bcast_packet(struct sk_buff *skb,
 			     struct batadv_hard_iface *recv_if);
 int batadv_recv_tt_query(struct sk_buff *skb,

net/batman-adv/soft-interface.c

@@ -758,6 +758,10 @@ static const struct {
 	{ "mgmt_tx_bytes" },
 	{ "mgmt_rx" },
 	{ "mgmt_rx_bytes" },
+	{ "frag_rx" },
+	{ "frag_rx_bytes" },
+	{ "frag_fwd" },
+	{ "frag_fwd_bytes" },
 	{ "tt_request_tx" },
 	{ "tt_request_rx" },
 	{ "tt_response_tx" },

net/batman-adv/types.h

@@ -85,6 +85,34 @@ struct batadv_hard_iface {
 	struct work_struct cleanup_work;
 };
 
+/**
+ * struct batadv_frag_table_entry - head in the fragment buffer table
+ * @head: head of list with fragments
+ * @lock: lock to protect the list of fragments
+ * @timestamp: time (jiffie) of last received fragment
+ * @seqno: sequence number of the fragments in the list
+ * @size: accumulated size of packets in list
+ */
+struct batadv_frag_table_entry {
+	struct hlist_head head;
+	spinlock_t lock; /* protects head */
+	unsigned long timestamp;
+	uint16_t seqno;
+	uint16_t size;
+};
+
+/**
+ * struct batadv_frag_list_entry - entry in a list of fragments
+ * @list: list node information
+ * @skb: fragment
+ * @no: fragment number in the set
+ */
+struct batadv_frag_list_entry {
+	struct hlist_node list;
+	struct sk_buff *skb;
+	uint8_t no;
+};
+
 /**
  * struct batadv_orig_node - structure for orig_list maintaining nodes of mesh
  * @orig: originator ethernet address
@@ -128,6 +156,7 @@ struct batadv_hard_iface {
  * @out_coding_list: list of nodes that can hear this orig
  * @in_coding_list_lock: protects in_coding_list
  * @out_coding_list_lock: protects out_coding_list
+ * @fragments: array with heads for fragment chains
  */
 struct batadv_orig_node {
 	uint8_t orig[ETH_ALEN];
@@ -174,6 +203,7 @@ struct batadv_orig_node {
 	spinlock_t in_coding_list_lock; /* Protects in_coding_list */
 	spinlock_t out_coding_list_lock; /* Protects out_coding_list */
 #endif
+	struct batadv_frag_table_entry fragments[BATADV_FRAG_BUFFER_COUNT];
 };
 
 /**
@@ -270,6 +300,10 @@ struct batadv_bcast_duplist_entry {
  * @BATADV_CNT_MGMT_TX_BYTES: transmitted routing protocol traffic bytes counter
  * @BATADV_CNT_MGMT_RX: received routing protocol traffic packet counter
  * @BATADV_CNT_MGMT_RX_BYTES: received routing protocol traffic bytes counter
+ * @BATADV_CNT_FRAG_RX: received fragment traffic packet counter
+ * @BATADV_CNT_FRAG_RX_BYTES: received fragment traffic bytes counter
+ * @BATADV_CNT_FRAG_FWD: forwarded fragment traffic packet counter
+ * @BATADV_CNT_FRAG_FWD_BYTES: forwarded fragment traffic bytes counter
  * @BATADV_CNT_TT_REQUEST_TX: transmitted tt req traffic packet counter
  * @BATADV_CNT_TT_REQUEST_RX: received tt req traffic packet counter
  * @BATADV_CNT_TT_RESPONSE_TX: transmitted tt resp traffic packet counter
@@ -307,6 +341,10 @@ enum batadv_counters {
 	BATADV_CNT_MGMT_TX_BYTES,
 	BATADV_CNT_MGMT_RX,
 	BATADV_CNT_MGMT_RX_BYTES,
+	BATADV_CNT_FRAG_RX,
+	BATADV_CNT_FRAG_RX_BYTES,
+	BATADV_CNT_FRAG_FWD,
+	BATADV_CNT_FRAG_FWD_BYTES,
 	BATADV_CNT_TT_REQUEST_TX,
 	BATADV_CNT_TT_REQUEST_RX,
 	BATADV_CNT_TT_RESPONSE_TX,