batman-adv: network coding - code and transmit packets if possible (3c12de9a) · Commits · 戴 / test

net/batman-adv/main.h

+6 −0

Original line number	Diff line number	Diff line
		@@ -302,4 +302,10 @@ static inline uint64_t batadv_sum_counter(struct batadv_priv *bat_priv,
		return sum;
		}

		/* Define a macro to reach the control buffer of the skb. The members of the
		* control buffer are defined in struct batadv_skb_cb in types.h.
		* The macro is inspired by the similar macro TCP_SKB_CB() in tcp.h.
		*/
		#define BATADV_SKB_CB(__skb) ((struct batadv_skb_cb *)&((__skb)->cb[0]))

		#endif /* _NET_BATMAN_ADV_MAIN_H_ */

net/batman-adv/network-coding.c

+401 −0

Original line number	Diff line number	Diff line
		@@ -797,6 +797,403 @@ static struct batadv_nc_path batadv_nc_get_path(struct batadv_priv bat_priv,
		return nc_path;
		}

		/**
		* batadv_nc_random_weight_tq - scale the receivers TQ-value to avoid unfair
		* selection of a receiver with slightly lower TQ than the other
		* @tq: to be weighted tq value
		*/
		static uint8_t batadv_nc_random_weight_tq(uint8_t tq)
		{
		uint8_t rand_val, rand_tq;

		get_random_bytes(&rand_val, sizeof(rand_val));

		/* randomize the estimated packet loss (max TQ - estimated TQ) */
		rand_tq = rand_val * (BATADV_TQ_MAX_VALUE - tq);

		/* normalize the randomized packet loss */
		rand_tq /= BATADV_TQ_MAX_VALUE;

		/* convert to (randomized) estimated tq again */
		return BATADV_TQ_MAX_VALUE - rand_tq;
		}

		/**
		* batadv_nc_memxor - XOR destination with source
		* @dst: byte array to XOR into
		* @src: byte array to XOR from
		* @len: length of destination array
		*/
		static void batadv_nc_memxor(char dst, const char src, unsigned int len)
		{
		unsigned int i;

		for (i = 0; i < len; ++i)
		dst[i] ^= src[i];
		}

		/**
		* batadv_nc_code_packets - code a received unicast_packet with an nc packet
		* into a coded_packet and send it
		* @bat_priv: the bat priv with all the soft interface information
		* @skb: data skb to forward
		* @ethhdr: pointer to the ethernet header inside the skb
		* @nc_packet: structure containing the packet to the skb can be coded with
		* @neigh_node: next hop to forward packet to
		*
		* Returns true if both packets are consumed, false otherwise.
		*/
		static bool batadv_nc_code_packets(struct batadv_priv *bat_priv,
		struct sk_buff *skb,
		struct ethhdr *ethhdr,
		struct batadv_nc_packet *nc_packet,
		struct batadv_neigh_node *neigh_node)
		{
		uint8_t tq_weighted_neigh, tq_weighted_coding;
		struct sk_buff skb_dest, skb_src;
		struct batadv_unicast_packet *packet1;
		struct batadv_unicast_packet *packet2;
		struct batadv_coded_packet *coded_packet;
		struct batadv_neigh_node neigh_tmp, router_neigh;
		struct batadv_neigh_node *router_coding = NULL;
		uint8_t first_source, first_dest, second_source, second_dest;
		__be32 packet_id1, packet_id2;
		size_t count;
		bool res = false;
		int coding_len;
		int unicast_size = sizeof(*packet1);
		int coded_size = sizeof(*coded_packet);
		int header_add = coded_size - unicast_size;

		router_neigh = batadv_orig_node_get_router(neigh_node->orig_node);
		if (!router_neigh)
		goto out;

		neigh_tmp = nc_packet->neigh_node;
		router_coding = batadv_orig_node_get_router(neigh_tmp->orig_node);
		if (!router_coding)
		goto out;

		tq_weighted_neigh = batadv_nc_random_weight_tq(router_neigh->tq_avg);
		tq_weighted_coding = batadv_nc_random_weight_tq(router_coding->tq_avg);

		/* Select one destination for the MAC-header dst-field based on
		* weighted TQ-values.
		*/
		if (tq_weighted_neigh >= tq_weighted_coding) {
		/* Destination from nc_packet is selected for MAC-header */
		first_dest = nc_packet->nc_path->next_hop;
		first_source = nc_packet->nc_path->prev_hop;
		second_dest = neigh_node->addr;
		second_source = ethhdr->h_source;
		packet1 = (struct batadv_unicast_packet *)nc_packet->skb->data;
		packet2 = (struct batadv_unicast_packet *)skb->data;
		packet_id1 = nc_packet->packet_id;
		packet_id2 = batadv_skb_crc32(skb,
		skb->data + sizeof(*packet2));
		} else {
		/* Destination for skb is selected for MAC-header */
		first_dest = neigh_node->addr;
		first_source = ethhdr->h_source;
		second_dest = nc_packet->nc_path->next_hop;
		second_source = nc_packet->nc_path->prev_hop;
		packet1 = (struct batadv_unicast_packet *)skb->data;
		packet2 = (struct batadv_unicast_packet *)nc_packet->skb->data;
		packet_id1 = batadv_skb_crc32(skb,
		skb->data + sizeof(*packet1));
		packet_id2 = nc_packet->packet_id;
		}

		/* Instead of zero padding the smallest data buffer, we
		* code into the largest.
		*/
		if (skb->len <= nc_packet->skb->len) {
		skb_dest = nc_packet->skb;
		skb_src = skb;
		} else {
		skb_dest = skb;
		skb_src = nc_packet->skb;
		}

		/* coding_len is used when decoding the packet shorter packet */
		coding_len = skb_src->len - unicast_size;

		if (skb_linearize(skb_dest) < 0 \|\| skb_linearize(skb_src) < 0)
		goto out;

		skb_push(skb_dest, header_add);

		coded_packet = (struct batadv_coded_packet *)skb_dest->data;
		skb_reset_mac_header(skb_dest);

		coded_packet->header.packet_type = BATADV_CODED;
		coded_packet->header.version = BATADV_COMPAT_VERSION;
		coded_packet->header.ttl = packet1->header.ttl;

		/* Info about first unicast packet */
		memcpy(coded_packet->first_source, first_source, ETH_ALEN);
		memcpy(coded_packet->first_orig_dest, packet1->dest, ETH_ALEN);
		coded_packet->first_crc = packet_id1;
		coded_packet->first_ttvn = packet1->ttvn;

		/* Info about second unicast packet */
		memcpy(coded_packet->second_dest, second_dest, ETH_ALEN);
		memcpy(coded_packet->second_source, second_source, ETH_ALEN);
		memcpy(coded_packet->second_orig_dest, packet2->dest, ETH_ALEN);
		coded_packet->second_crc = packet_id2;
		coded_packet->second_ttl = packet2->header.ttl;
		coded_packet->second_ttvn = packet2->ttvn;
		coded_packet->coded_len = htons(coding_len);

		/* This is where the magic happens: Code skb_src into skb_dest */
		batadv_nc_memxor(skb_dest->data + coded_size,
		skb_src->data + unicast_size, coding_len);

		/* Update counters accordingly */
		if (BATADV_SKB_CB(skb_src)->decoded &&
		BATADV_SKB_CB(skb_dest)->decoded) {
		/* Both packets are recoded */
		count = skb_src->len + ETH_HLEN;
		count += skb_dest->len + ETH_HLEN;
		batadv_add_counter(bat_priv, BATADV_CNT_NC_RECODE, 2);
		batadv_add_counter(bat_priv, BATADV_CNT_NC_RECODE_BYTES, count);
		} else if (!BATADV_SKB_CB(skb_src)->decoded &&
		!BATADV_SKB_CB(skb_dest)->decoded) {
		/* Both packets are newly coded */
		count = skb_src->len + ETH_HLEN;
		count += skb_dest->len + ETH_HLEN;
		batadv_add_counter(bat_priv, BATADV_CNT_NC_CODE, 2);
		batadv_add_counter(bat_priv, BATADV_CNT_NC_CODE_BYTES, count);
		} else if (BATADV_SKB_CB(skb_src)->decoded &&
		!BATADV_SKB_CB(skb_dest)->decoded) {
		/* skb_src recoded and skb_dest is newly coded */
		batadv_inc_counter(bat_priv, BATADV_CNT_NC_RECODE);
		batadv_add_counter(bat_priv, BATADV_CNT_NC_RECODE_BYTES,
		skb_src->len + ETH_HLEN);
		batadv_inc_counter(bat_priv, BATADV_CNT_NC_CODE);
		batadv_add_counter(bat_priv, BATADV_CNT_NC_CODE_BYTES,
		skb_dest->len + ETH_HLEN);
		} else if (!BATADV_SKB_CB(skb_src)->decoded &&
		BATADV_SKB_CB(skb_dest)->decoded) {
		/* skb_src is newly coded and skb_dest is recoded */
		batadv_inc_counter(bat_priv, BATADV_CNT_NC_CODE);
		batadv_add_counter(bat_priv, BATADV_CNT_NC_CODE_BYTES,
		skb_src->len + ETH_HLEN);
		batadv_inc_counter(bat_priv, BATADV_CNT_NC_RECODE);
		batadv_add_counter(bat_priv, BATADV_CNT_NC_RECODE_BYTES,
		skb_dest->len + ETH_HLEN);
		}

		/* skb_src is now coded into skb_dest, so free it */
		kfree_skb(skb_src);

		/* avoid duplicate free of skb from nc_packet */
		nc_packet->skb = NULL;
		batadv_nc_packet_free(nc_packet);

		/* Send the coded packet and return true */
		batadv_send_skb_packet(skb_dest, neigh_node->if_incoming, first_dest);
		res = true;
		out:
		if (router_neigh)
		batadv_neigh_node_free_ref(router_neigh);
		if (router_coding)
		batadv_neigh_node_free_ref(router_coding);
		return res;
		}

		/**
		* batadv_nc_skb_coding_possible - true if a decoded skb is available at dst.
		* @skb: data skb to forward
		* @dst: destination mac address of the other skb to code with
		* @src: source mac address of skb
		*
		* Whenever we network code a packet we have to check whether we received it in
		* a network coded form. If so, we may not be able to use it for coding because
		* some neighbors may also have received (overheard) the packet in the network
		* coded form without being able to decode it. It is hard to know which of the
		* neighboring nodes was able to decode the packet, therefore we can only
		* re-code the packet if the source of the previous encoded packet is involved.
		* Since the source encoded the packet we can be certain it has all necessary
		* decode information.
		*
		* Returns true if coding of a decoded packet is allowed.
		*/
		static bool batadv_nc_skb_coding_possible(struct sk_buff *skb,
		uint8_t dst, uint8_t src)
		{
		if (BATADV_SKB_CB(skb)->decoded && !batadv_compare_eth(dst, src))
		return false;
		else
		return true;
		}

		/**
		* batadv_nc_path_search - Find the coding path matching in_nc_node and
		* out_nc_node to retrieve a buffered packet that can be used for coding.
		* @bat_priv: the bat priv with all the soft interface information
		* @in_nc_node: pointer to skb next hop's neighbor nc node
		* @out_nc_node: pointer to skb source's neighbor nc node
		* @skb: data skb to forward
		* @eth_dst: next hop mac address of skb
		*
		* Returns true if coding of a decoded skb is allowed.
		*/
		static struct batadv_nc_packet *
		batadv_nc_path_search(struct batadv_priv *bat_priv,
		struct batadv_nc_node *in_nc_node,
		struct batadv_nc_node *out_nc_node,
		struct sk_buff *skb,
		uint8_t *eth_dst)
		{
		struct batadv_nc_path *nc_path, nc_path_key;
		struct batadv_nc_packet *nc_packet_out = NULL;
		struct batadv_nc_packet nc_packet, nc_packet_tmp;
		struct batadv_hashtable *hash = bat_priv->nc.coding_hash;
		int idx;

		if (!hash)
		return NULL;

		/* Create almost path key */
		batadv_nc_hash_key_gen(&nc_path_key, in_nc_node->addr,
		out_nc_node->addr);
		idx = batadv_nc_hash_choose(&nc_path_key, hash->size);

		/* Check for coding opportunities in this nc_path */
		rcu_read_lock();
		hlist_for_each_entry_rcu(nc_path, &hash->table[idx], hash_entry) {
		if (!batadv_compare_eth(nc_path->prev_hop, in_nc_node->addr))
		continue;

		if (!batadv_compare_eth(nc_path->next_hop, out_nc_node->addr))
		continue;

		spin_lock_bh(&nc_path->packet_list_lock);
		if (list_empty(&nc_path->packet_list)) {
		spin_unlock_bh(&nc_path->packet_list_lock);
		continue;
		}

		list_for_each_entry_safe(nc_packet, nc_packet_tmp,
		&nc_path->packet_list, list) {
		if (!batadv_nc_skb_coding_possible(nc_packet->skb,
		eth_dst,
		in_nc_node->addr))
		continue;

		/* Coding opportunity is found! */
		list_del(&nc_packet->list);
		nc_packet_out = nc_packet;
		break;
		}

		spin_unlock_bh(&nc_path->packet_list_lock);
		break;
		}
		rcu_read_unlock();

		return nc_packet_out;
		}

		/**
		* batadv_nc_skb_src_search - Loops through the list of neighoring nodes of the
		* skb's sender (may be equal to the originator).
		* @bat_priv: the bat priv with all the soft interface information
		* @skb: data skb to forward
		* @eth_dst: next hop mac address of skb
		* @eth_src: source mac address of skb
		* @in_nc_node: pointer to skb next hop's neighbor nc node
		*
		* Returns an nc packet if a suitable coding packet was found, NULL otherwise.
		*/
		static struct batadv_nc_packet *
		batadv_nc_skb_src_search(struct batadv_priv *bat_priv,
		struct sk_buff *skb,
		uint8_t *eth_dst,
		uint8_t *eth_src,
		struct batadv_nc_node *in_nc_node)
		{
		struct batadv_orig_node *orig_node;
		struct batadv_nc_node *out_nc_node;
		struct batadv_nc_packet *nc_packet = NULL;

		orig_node = batadv_orig_hash_find(bat_priv, eth_src);
		if (!orig_node)
		return NULL;

		rcu_read_lock();
		list_for_each_entry_rcu(out_nc_node,
		&orig_node->out_coding_list, list) {
		/* Check if the skb is decoded and if recoding is possible */
		if (!batadv_nc_skb_coding_possible(skb,
		out_nc_node->addr, eth_src))
		continue;

		/* Search for an opportunity in this nc_path */
		nc_packet = batadv_nc_path_search(bat_priv, in_nc_node,
		out_nc_node, skb, eth_dst);
		if (nc_packet)
		break;
		}
		rcu_read_unlock();

		batadv_orig_node_free_ref(orig_node);
		return nc_packet;
		}

		/**
		* batadv_nc_skb_dst_search - Loops through list of neighboring nodes to dst.
		* @skb: data skb to forward
		* @neigh_node: next hop to forward packet to
		* @ethhdr: pointer to the ethernet header inside the skb
		*
		* Loops through list of neighboring nodes the next hop has a good connection to
		* (receives OGMs with a sufficient quality). We need to find a neighbor of our
		* next hop that potentially sent a packet which our next hop also received
		* (overheard) and has stored for later decoding.
		*
		* Returns true if the skb was consumed (encoded packet sent) or false otherwise
		*/
		static bool batadv_nc_skb_dst_search(struct sk_buff *skb,
		struct batadv_neigh_node *neigh_node,
		struct ethhdr *ethhdr)
		{
		struct net_device *netdev = neigh_node->if_incoming->soft_iface;
		struct batadv_priv *bat_priv = netdev_priv(netdev);
		struct batadv_orig_node *orig_node = neigh_node->orig_node;
		struct batadv_nc_node *nc_node;
		struct batadv_nc_packet *nc_packet = NULL;

		rcu_read_lock();
		list_for_each_entry_rcu(nc_node, &orig_node->in_coding_list, list) {
		/* Search for coding opportunity with this in_nc_node */
		nc_packet = batadv_nc_skb_src_search(bat_priv, skb,
		neigh_node->addr,
		ethhdr->h_source, nc_node);

		/* Opportunity was found, so stop searching */
		if (nc_packet)
		break;
		}
		rcu_read_unlock();

		if (!nc_packet)
		return false;

		/* Code and send packets */
		if (batadv_nc_code_packets(bat_priv, skb, ethhdr, nc_packet,
		neigh_node))
		return true;

		/* out of mem ? Coding failed - we have to free the buffered packet
		* to avoid memleaks. The skb passed as argument will be dealt with
		* by the calling function.
		*/
		batadv_nc_send_packet(nc_packet);
		return false;
		}

		/**
		* batadv_nc_skb_add_to_path - buffer skb for later encoding / decoding
		* @skb: skb to add to path
		@@ -862,6 +1259,10 @@ bool batadv_nc_skb_forward(struct sk_buff *skb,
		if (packet->header.packet_type != BATADV_UNICAST)
		goto out;

		/* Try to find a coding opportunity and send the skb if one is found */
		if (batadv_nc_skb_dst_search(skb, neigh_node, ethhdr))
		return true;

		/* Find or create a nc_path for this src-dst pair */
		nc_path = batadv_nc_get_path(bat_priv,
		bat_priv->nc.coding_hash,

net/batman-adv/packet.h

+33 −0

Original line number	Diff line number	Diff line
		@@ -30,6 +30,7 @@ enum batadv_packettype {
		BATADV_TT_QUERY = 0x07,
		BATADV_ROAM_ADV = 0x08,
		BATADV_UNICAST_4ADDR = 0x09,
		BATADV_CODED = 0x0a,
		};

		/**
		@@ -278,4 +279,36 @@ struct batadv_tt_change {
		uint8_t addr[ETH_ALEN];
		} __packed;

		/**
		* struct batadv_coded_packet - network coded packet
		* @header: common batman packet header and ttl of first included packet
		* @reserved: Align following fields to 2-byte boundaries
		* @first_source: original source of first included packet
		* @first_orig_dest: original destinal of first included packet
		* @first_crc: checksum of first included packet
		* @first_ttvn: tt-version number of first included packet
		* @second_ttl: ttl of second packet
		* @second_dest: second receiver of this coded packet
		* @second_source: original source of second included packet
		* @second_orig_dest: original destination of second included packet
		* @second_crc: checksum of second included packet
		* @second_ttvn: tt version number of second included packet
		* @coded_len: length of network coded part of the payload
		*/
		struct batadv_coded_packet {
		struct batadv_header header;
		uint8_t first_ttvn;
		/* uint8_t first_dest[ETH_ALEN]; - saved in mac header destination */
		uint8_t first_source[ETH_ALEN];
		uint8_t first_orig_dest[ETH_ALEN];
		__be32 first_crc;
		uint8_t second_ttl;
		uint8_t second_ttvn;
		uint8_t second_dest[ETH_ALEN];
		uint8_t second_source[ETH_ALEN];
		uint8_t second_orig_dest[ETH_ALEN];
		__be32 second_crc;
		uint16_t coded_len;
		};

		#endif /* _NET_BATMAN_ADV_PACKET_H_ */

net/batman-adv/soft-interface.c

+6 −0

Original line number	Diff line number	Diff line
		@@ -665,6 +665,12 @@ static const struct {
		{ "dat_put_rx" },
		{ "dat_cached_reply_tx" },
		#endif
		#ifdef CONFIG_BATMAN_ADV_NC
		{ "nc_code" },
		{ "nc_code_bytes" },
		{ "nc_recode" },
		{ "nc_recode_bytes" },
		#endif
		};

		static void batadv_get_strings(struct net_device *dev, uint32_t stringset,

net/batman-adv/types.h

+20 −0

Original line number	Diff line number	Diff line
		@@ -275,6 +275,10 @@ struct batadv_bcast_duplist_entry {
		* @BATADV_CNT_DAT_PUT_RX: received dht PUT traffic packet counter
		* @BATADV_CNT_DAT_CACHED_REPLY_TX: transmitted dat cache reply traffic packet
		* counter
		* @BATADV_CNT_NC_CODE: transmitted nc-combined traffic packet counter
		* @BATADV_CNT_NC_CODE_BYTES: transmitted nc-combined traffic bytes counter
		* @BATADV_CNT_NC_RECODE: transmitted nc-recombined traffic packet counter
		* @BATADV_CNT_NC_RECODE_BYTES: transmitted nc-recombined traffic bytes counter
		* @BATADV_CNT_NUM: number of traffic counters
		*/
		enum batadv_counters {
		@@ -301,6 +305,12 @@ enum batadv_counters {
		BATADV_CNT_DAT_PUT_TX,
		BATADV_CNT_DAT_PUT_RX,
		BATADV_CNT_DAT_CACHED_REPLY_TX,
		#endif
		#ifdef CONFIG_BATMAN_ADV_NC
		BATADV_CNT_NC_CODE,
		BATADV_CNT_NC_CODE_BYTES,
		BATADV_CNT_NC_RECODE,
		BATADV_CNT_NC_RECODE_BYTES,
		#endif
		BATADV_CNT_NUM,
		};
		@@ -796,6 +806,16 @@ struct batadv_nc_packet {
		struct batadv_nc_path *nc_path;
		};

		/**
		* batadv_skb_cb - control buffer structure used to store private data relevant
		* to batman-adv in the skb->cb buffer in skbs.
		* @decoded: Marks a skb as decoded, which is checked when searching for coding
		* opportunities in network-coding.c
		*/
		struct batadv_skb_cb {
		bool decoded;
		};

		/**
		* struct batadv_forw_packet - structure for bcast packets to be sent/forwarded
		* @list: list node for batadv_socket_client::queue_list

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