[batadv,v12 2/5] batman-adv: split DAT cache into DAT cache and DAT DHT

["Linus Lüssing" <linus.luessing@c0d3.blue>]

Similar to the translation table split the (mostly) locally maintained
DAT cache and the DAT DHT concepts into two separate tables.

This eases the monitoring and debugging regarding the origin of DAT
entries. And allows to apply differing properties to entries in the DAT
cache and DAT DHT in the future, like distinct timeouts.

Signed-off-by: Linus Lüssing <linus.luessing@c0d3.blue>
---
 include/uapi/linux/batman_adv.h        |   5 +
 net/batman-adv/distributed-arp-table.c | 581 ++++++++++++++++++++-----
 net/batman-adv/distributed-arp-table.h |  13 +-
 net/batman-adv/netlink.c               |   8 +-
 net/batman-adv/routing.c               |   7 +-
 net/batman-adv/types.h                 |   7 +-
 6 files changed, 511 insertions(+), 110 deletions(-)

diff --git a/include/uapi/linux/batman_adv.h b/include/uapi/linux/batman_adv.h
index 936bcac270b5..7379c1509f77 100644
--- a/include/uapi/linux/batman_adv.h
+++ b/include/uapi/linux/batman_adv.h
@@ -613,6 +613,11 @@ enum batadv_nl_commands {
 	 */
 	BATADV_CMD_SET_VLAN,
 
+	/**
+	 * @BATADV_CMD_GET_DAT_DHT: Query list of DAT DHT entries
+	 */
+	BATADV_CMD_GET_DAT_DHT,
+
 	/* add new commands above here */
 
 	/**
diff --git a/net/batman-adv/distributed-arp-table.c b/net/batman-adv/distributed-arp-table.c
index 1a0eb9d9812e..af08812c7ecd 100644
--- a/net/batman-adv/distributed-arp-table.c
+++ b/net/batman-adv/distributed-arp-table.c
@@ -211,17 +211,17 @@ static bool batadv_dat_to_purge(struct batadv_dat_entry *dat_entry)
 }
 
 /**
- * __batadv_dat_purge() - delete entries from the DAT local storage
- * @bat_priv: the bat priv with all the mesh interface information
+ * __batadv_dat_purge() - delete entries from a DAT hash table
+ * @hash: the hash table to delete from
  * @to_purge: function in charge to decide whether an entry has to be purged or
  *	      not. This function takes the dat_entry as argument and has to
  *	      returns a boolean value: true is the entry has to be deleted,
  *	      false otherwise
  *
- * Loops over each entry in the DAT local storage and deletes it if and only if
+ * Loops over each entry in a DAT hash table and deletes it if and only if
  * the to_purge function passed as argument returns true.
  */
-static void __batadv_dat_purge(struct batadv_priv *bat_priv,
+static void __batadv_dat_purge(struct batadv_hashtable *hash,
 			       bool (*to_purge)(struct batadv_dat_entry *))
 {
 	spinlock_t *list_lock; /* protects write access to the hash lists */
@@ -230,12 +230,12 @@ static void __batadv_dat_purge(struct batadv_priv *bat_priv,
 	struct hlist_head *head;
 	u32 i;
 
-	if (!bat_priv->dat.hash)
+	if (!hash)
 		return;
 
-	for (i = 0; i < bat_priv->dat.hash->size; i++) {
-		head = &bat_priv->dat.hash->table[i];
-		list_lock = &bat_priv->dat.hash->list_locks[i];
+	for (i = 0; i < hash->size; i++) {
+		head = &hash->table[i];
+		list_lock = &hash->list_locks[i];
 
 		spin_lock_bh(list_lock);
 		hlist_for_each_entry_safe(dat_entry, node_tmp, head,
@@ -268,7 +268,8 @@ static void batadv_dat_purge(struct work_struct *work)
 	priv_dat = container_of(delayed_work, struct batadv_priv_dat, work);
 	bat_priv = container_of(priv_dat, struct batadv_priv, dat);
 
-	__batadv_dat_purge(bat_priv, batadv_dat_to_purge);
+	__batadv_dat_purge(bat_priv->dat.cache_hash, batadv_dat_to_purge);
+	__batadv_dat_purge(bat_priv->dat.dht_hash, batadv_dat_to_purge);
 	batadv_dat_start_timer(bat_priv);
 }
 
@@ -387,19 +388,17 @@ static u32 batadv_hash_dat(const void *data, u32 size)
 }
 
 /**
- * batadv_dat_entry_hash_find() - look for a given dat_entry in the local hash
- * table
- * @bat_priv: the bat priv with all the mesh interface information
+ * batadv_dat_entry_hash_find() - look for a given dat_entry in a hash table
+ * @hash: the hash table to search in
  * @ip: search key
  * @vid: VLAN identifier
  *
  * Return: the dat_entry if found, NULL otherwise.
  */
 static struct batadv_dat_entry *
-batadv_dat_entry_hash_find(struct batadv_priv *bat_priv, __be32 ip,
+batadv_dat_entry_hash_find(struct batadv_hashtable *hash, __be32 ip,
 			   unsigned short vid)
 {
-	struct batadv_hashtable *hash = bat_priv->dat.hash;
 	struct batadv_dat_entry *dat_entry_tmp = NULL;
 	struct batadv_dat_entry *dat_entry;
 	struct batadv_dat_entry to_find;
@@ -434,29 +433,64 @@ batadv_dat_entry_hash_find(struct batadv_priv *bat_priv, __be32 ip,
 	return dat_entry_tmp;
 }
 
+/**
+ * batadv_dat_cache_entry_find() - look for a given dat_entry in the DAT cache
+ * @bat_priv: the bat priv with all the mesh interface information
+ * @ip: search key
+ * @vid: VLAN identifier
+ *
+ * Return: the dat_entry if found, NULL otherwise.
+ */
+static inline struct batadv_dat_entry *
+batadv_dat_cache_entry_find(struct batadv_priv *bat_priv, __be32 ip,
+			    unsigned short vid)
+{
+	return batadv_dat_entry_hash_find(bat_priv->dat.cache_hash, ip, vid);
+}
+
+/**
+ * batadv_dat_dht_entry_find() - look for a given dat_entry in the DAT DHT
+ * @bat_priv: the bat priv with all the mesh interface information
+ * @ip: search key
+ * @vid: VLAN identifier
+ *
+ * Return: the dat_entry if found, NULL otherwise.
+ */
+static inline struct batadv_dat_entry *
+batadv_dat_dht_entry_find(struct batadv_priv *bat_priv, __be32 ip,
+			  unsigned short vid)
+{
+	return batadv_dat_entry_hash_find(bat_priv->dat.dht_hash, ip, vid);
+}
+
 /**
  * batadv_dat_entry_add() - add a new dat entry or update it if already exists
  * @bat_priv: the bat priv with all the mesh interface information
+ * @hash: the hash table to add to
  * @ip: ipv4 to add/edit
  * @mac_addr: mac address to assign to the given ipv4
  * @vid: VLAN identifier
+ * @tablename: the name of the hash table to add to
  */
-static void batadv_dat_entry_add(struct batadv_priv *bat_priv, __be32 ip,
-				 u8 *mac_addr, unsigned short vid)
+static void
+batadv_dat_entry_add(struct batadv_priv *bat_priv,
+		     struct batadv_hashtable *hash, __be32 ip,
+		     u8 *mac_addr, unsigned short vid,
+		     const char *tablename)
 {
 	u64 u64_mac = ether_addr_to_u64(mac_addr);
 	struct batadv_dat_entry *dat_entry;
 	int hash_added;
 
-	dat_entry = batadv_dat_entry_hash_find(bat_priv, ip, vid);
+	dat_entry = batadv_dat_entry_hash_find(hash, ip, vid);
 	/* if this entry is already known, just update it */
 	if (dat_entry) {
 		atomic64_set(&dat_entry->mac_addr, u64_mac);
 
 		dat_entry->last_update = jiffies;
 		batadv_dbg(BATADV_DBG_DAT, bat_priv,
-			   "Entry updated: %pI4 %pM (vid: %d)\n",
-			   &dat_entry->ip, mac_addr,
+			   "Entry updated in %s: %pI4 %pM (vid: %d)\n",
+			   tablename, &dat_entry->ip, mac_addr,
 			   batadv_print_vid(vid));
 		goto out;
 	}
@@ -472,7 +506,7 @@ static void batadv_dat_entry_add(struct batadv_priv *bat_priv, __be32 ip,
 	kref_init(&dat_entry->refcount);
 
 	kref_get(&dat_entry->refcount);
-	hash_added = batadv_hash_add(bat_priv->dat.hash, batadv_compare_dat,
+	hash_added = batadv_hash_add(hash, batadv_compare_dat,
 				     batadv_hash_dat, dat_entry,
 				     &dat_entry->hash_entry);
 
@@ -482,13 +516,44 @@ static void batadv_dat_entry_add(struct batadv_priv *bat_priv, __be32 ip,
 		goto out;
 	}
 
-	batadv_dbg(BATADV_DBG_DAT, bat_priv, "New entry added: %pI4 %pM (vid: %d)\n",
-		   &dat_entry->ip, mac_addr, batadv_print_vid(vid));
+	batadv_dbg(BATADV_DBG_DAT, bat_priv,
+		   "New entry added in %s: %pI4 %pM (vid: %d)\n",
+		   tablename, &dat_entry->ip, mac_addr, batadv_print_vid(vid));
 
 out:
 	batadv_dat_entry_put(dat_entry);
 }
 
+/**
+ * batadv_dat_cache_entry_add() - add or update dat_entry in the DAT cache
+ * @bat_priv: the bat priv with all the soft interface information
+ * @ip: ipv4 to add/edit
+ * @mac_addr: mac address to assign to the given ipv4
+ * @vid: VLAN identifier
+ */
+static inline void
+batadv_dat_cache_entry_add(struct batadv_priv *bat_priv, __be32 ip,
+			   u8 *mac_addr, unsigned short vid)
+{
+	batadv_dat_entry_add(bat_priv, bat_priv->dat.cache_hash, ip, mac_addr,
+			     vid, "cache");
+}
+
+/**
+ * batadv_dat_dht_entry_add() - add or update dat_entry in the DAT DHT
+ * @bat_priv: the bat priv with all the mesh interface information
+ * @ip: ipv4 to add/edit
+ * @mac_addr: mac address to assign to the given ipv4
+ * @vid: VLAN identifier
+ */
+static inline void
+batadv_dat_dht_entry_add(struct batadv_priv *bat_priv, __be32 ip,
+			 u8 *mac_addr, unsigned short vid)
+{
+	batadv_dat_entry_add(bat_priv, bat_priv->dat.dht_hash, ip, mac_addr,
+			     vid, "dht");
+}
+
 #ifdef CONFIG_BATMAN_ADV_DEBUG
 
 /**
@@ -692,12 +757,77 @@ static void batadv_choose_next_candidate(struct batadv_priv *bat_priv,
 	*last_max = max;
 }
 
+/**
+ * batadv_dat_cmp_self_candidate() - check if we are a better DHT candidate
+ * @bat_priv: the bat priv with all the mesh interface information
+ * @cands: candidates array
+ * @ip_key: key to look up in the DHT
+ * @last_max: address of the last selected candidate
+ *
+ * Check if we are a better candidate than the last placed, selected DHT
+ * candidate for the given IP address key.
+ *
+ * Return: true if we are a better candidate, false otherwise.
+ */
+static bool batadv_dat_cmp_self_candidate(struct batadv_priv *bat_priv,
+					  struct batadv_dat_candidate *cands,
+					  batadv_dat_addr_t ip_key,
+					  batadv_dat_addr_t last_max)
+{
+	struct batadv_hard_iface *primary_if = NULL;
+	struct batadv_dat_candidate *last_cand;
+	const unsigned char *own_orig_addr;
+	batadv_dat_addr_t own_dat_addr;
+	batadv_dat_addr_t tmp_max;
+	bool ret = false;
+
+	last_cand = &cands[BATADV_DAT_CANDIDATES_NUM - 1];
+
+	/* a free slot? then it is for us */
+	if (last_cand->type == BATADV_DAT_CANDIDATE_NOT_FOUND) {
+		ret = true;
+		goto out;
+	}
+
+	primary_if = batadv_primary_if_get_selected(bat_priv);
+	if (!primary_if)
+		return false;
+
+	own_orig_addr = primary_if->net_dev->dev_addr;
+	own_dat_addr = batadv_choose_orig(own_orig_addr, BATADV_DAT_ADDR_MAX);
+	tmp_max = BATADV_DAT_ADDR_MAX - own_dat_addr + ip_key;
+
+	/* check if we are a better candidate than the last placed,
+	 * selected candidate node
+	 */
+	if (tmp_max < last_max)
+		goto out;
+
+	/* this is a hash collision with the last placed, selected candidate.
+	 * Choose the one with the lowest address
+	 */
+	if (tmp_max == last_max &&
+	    memcmp(own_orig_addr, last_cand->orig_node->orig, ETH_ALEN) >= 0)
+		goto out;
+
+	ret = true;
+out:
+	if (ret)
+		batadv_dbg(BATADV_DBG_DAT, bat_priv,
+			   "%s(): self-candidate for hash(IP)=%u, dist=%i\n",
+			   __func__, ip_key, primary_if ? tmp_max : -1);
+
+	batadv_hardif_put(primary_if);
+	return ret;
+}
+
 /**
  * batadv_dat_select_candidates() - select the nodes which the DHT message has
  *  to be sent to
  * @bat_priv: the bat priv with all the mesh interface information
  * @ip_dst: ipv4 to look up in the DHT
  * @vid: VLAN identifier
+ * @self_is_candidate: stores if we are a candidate (must not be NULL)
  *
  * An originator O is selected if and only if its DHT_ID value is one of three
  * closest values (from the LEFT, with wrap around if needed) then the hash
@@ -707,7 +837,7 @@ static void batadv_choose_next_candidate(struct batadv_priv *bat_priv,
  */
 static struct batadv_dat_candidate *
 batadv_dat_select_candidates(struct batadv_priv *bat_priv, __be32 ip_dst,
-			     unsigned short vid)
+			     unsigned short vid, bool *self_is_candidate)
 {
 	batadv_dat_addr_t last_max = BATADV_DAT_ADDR_MAX;
 	struct batadv_dat_candidate *res;
@@ -735,6 +865,9 @@ batadv_dat_select_candidates(struct batadv_priv *bat_priv, __be32 ip_dst,
 		batadv_choose_next_candidate(bat_priv, res, select, ip_key,
 					     &last_max);
 
+	if (batadv_dat_cmp_self_candidate(bat_priv, res, ip_key, last_max))
+		*self_is_candidate = true;
+
 	return res;
 }
 
@@ -835,9 +968,61 @@ batadv_dat_arp_self_reply(struct batadv_priv *bat_priv, __be32 ip_src,
 	return 0;
 }
 
+/**
+ * batadv_dat_dht_get_self_reply() - reply to our DHT_GET locally
+ * @bat_priv: the bat priv with all the mesh interface information
+ * @ip_src: ARP request sender IP (and ARP reply target IP)
+ * @ip_dst: ARP request target IP (and ARP reply sender IP)
+ * @hw_src: Ethernet source and ARP sender MAC of ARP request
+ * @hw_dst: Ethernet destination and ARP target MAC of ARP request
+ * @vid: VLAN identifier (optional, set to zero otherwise)
+ * @arp_len: ARP packet size, including ethernet frame
+ *
+ * If we have a suitable response in our local DAT DHT for a local
+ * ARP request and are a suitable responder then generate and respond
+ * with an ARP reply locally.
+ *
+ * Return: false if we could not find a DAT DHT entry locally or if we
+ * were a suitable responder but could not generate an ARP reply
+ * (e.g. due to out-of-memory), true otherwise.
+ */
+static bool
+batadv_dat_dht_get_self_reply(struct batadv_priv *bat_priv, __be32 ip_src,
+			      __be32 ip_dst, u8 *hw_src, unsigned short vid,
+			      unsigned int arp_len)
+{
+	struct batadv_dat_entry *dat_entry;
+	u8 mac[ETH_ALEN] __aligned(2);
+	u64 u64_mac;
+	int ret;
+
+	dat_entry = batadv_dat_dht_entry_find(bat_priv, ip_dst, vid);
+	if (!dat_entry)
+		return false;
+
+	u64_mac = atomic64_read(&dat_entry->mac_addr);
+	u64_to_ether_addr(u64_mac, mac);
+
+	/* we are a selected DAT DHT candidate, our DAT DHT entry should get
+	 * updates, we can therefore safely copy it to our DAT cache for now
+	 */
+	batadv_dat_cache_entry_add(bat_priv, ip_dst, mac, vid);
+
+	ret = batadv_dat_arp_self_reply(bat_priv, ip_src, ip_dst, hw_src, mac,
+					vid, arp_len);
+	if (!ret)
+		batadv_dbg(BATADV_DBG_DAT, bat_priv,
+			   "ARP request for %pI4 replied locally (via local DHT)\n",
+			   &ip_dst);
+
+	batadv_dat_entry_put(dat_entry);
+	return (ret != -ENOMEM);
+}
+
 /**
  * batadv_dat_forward_data() - copy and send payload to the selected candidates
  * @bat_priv: the bat priv with all the mesh interface information
+ * @cands: candidates array
  * @skb: payload to send
  * @ip: the DHT key
  * @vid: VLAN identifier
@@ -850,37 +1035,33 @@ batadv_dat_arp_self_reply(struct batadv_priv *bat_priv, __be32 ip_src,
  * otherwise.
  */
 static bool batadv_dat_forward_data(struct batadv_priv *bat_priv,
+				    struct batadv_dat_candidate *cands,
 				    struct sk_buff *skb, __be32 ip,
 				    unsigned short vid, int packet_subtype)
 {
 	struct batadv_neigh_node *neigh_node = NULL;
-	struct batadv_dat_candidate *cand;
 	struct sk_buff *tmp_skb;
 	bool ret = false;
 	int send_status;
 	int i;
 
-	cand = batadv_dat_select_candidates(bat_priv, ip, vid);
-	if (!cand)
-		return ret;
-
 	batadv_dbg(BATADV_DBG_DAT, bat_priv, "DHT_SEND for %pI4\n", &ip);
 
 	for (i = 0; i < BATADV_DAT_CANDIDATES_NUM; i++) {
-		if (cand[i].type == BATADV_DAT_CANDIDATE_NOT_FOUND)
+		if (cands[i].type == BATADV_DAT_CANDIDATE_NOT_FOUND)
 			continue;
 
-		neigh_node = batadv_orig_router_get(cand[i].orig_node,
+		neigh_node = batadv_orig_router_get(cands[i].orig_node,
 						    BATADV_IF_DEFAULT);
 		if (!neigh_node)
-			goto free_orig;
+			continue;
 
 		tmp_skb = pskb_copy_for_clone(skb, GFP_ATOMIC);
 		if (!tmp_skb)
 			goto free_neigh;
 
 		if (!batadv_send_skb_prepare_unicast_4addr(bat_priv, tmp_skb,
-							   cand[i].orig_node,
+							   cands[i].orig_node,
 							   packet_subtype)) {
 			kfree_skb(tmp_skb);
 			goto free_neigh;
@@ -905,11 +1086,112 @@ static bool batadv_dat_forward_data(struct batadv_priv *bat_priv,
 		}
 free_neigh:
 		batadv_neigh_node_put(neigh_node);
-free_orig:
-		batadv_orig_node_put(cand[i].orig_node);
 	}
 
-	kfree(cand);
+	return ret;
+}
+
+/**
+ * batadv_dat_candidates_free() - free a candidates array
+ * @cands: the candidates array to free
+ *
+ * Free the given candidate array and release any potential orig node references
+ * it held.
+ *
+ * If @cands is NULL, no operation is performed.
+ */
+static void batadv_dat_candidates_free(struct batadv_dat_candidate *cands)
+{
+	if (!cands)
+		return;
+
+	for (int i = 0; i < BATADV_DAT_CANDIDATES_NUM; i++)
+		if (cands[i].type == BATADV_DAT_CANDIDATE_ORIG)
+			batadv_orig_node_put(cands[i].orig_node);
+
+	kfree(cands);
+}
+
+/**
+ * batadv_dat_forward_dht_put() - send payload via DHT_PUT to DAT candidates
+ * @bat_priv: the bat priv with all the mesh interface information
+ * @skb: payload to send
+ * @ip: the DHT key
+ * @hw_addr: the MAC address which the IP resolves to
+ * @vid: VLAN identifier
+ *
+ * Send the given payload via a DAT DHT_PUT message to the selected
+ * candidates.
+ *
+ * Return: true if the packet is sent to at least one candidate, false
+ * otherwise.
+ */
+static bool
+batadv_dat_forward_dht_put(struct batadv_priv *bat_priv, struct sk_buff *skb,
+			   __be32 ip, u8 *hw_addr, unsigned short vid)
+{
+	struct batadv_dat_candidate *cands;
+	bool self_is_candidate = false;
+	bool ret;
+
+	cands = batadv_dat_select_candidates(bat_priv, ip, vid,
+					     &self_is_candidate);
+	if (!cands)
+		return false;
+
+	if (self_is_candidate)
+		batadv_dat_dht_entry_add(bat_priv, ip, hw_addr, vid);
+
+	ret = batadv_dat_forward_data(bat_priv, cands, skb, ip, vid,
+				      BATADV_P_DAT_DHT_PUT);
+
+	batadv_dat_candidates_free(cands);
+	return ret;
+}
+
+/**
+ * batadv_dat_forward_dht_get() - send payload via DHT_GET to DAT candidates
+ * @bat_priv: the bat priv with all the mesh interface information
+ * @skb: payload to send
+ * @ip_src: ARP sender IP
+ * @ip_dst: ARP target IP
+ * @hw_src: Ethernet source and ARP sender MAC
+ * @hw_dst: Ethernet destination and ARP target MAC
+ * @vid: VLAN identifier
+ * @arp_len: ARP packet size, including ethernet frame
+ *
+ * Send the given payload via a DAT DHT_GET message to the selected
+ * candidates.
+ *
+ * Return: true if the packet is sent to at least one candidate, false
+ * otherwise.
+ */
+static bool
+batadv_dat_forward_dht_get(struct batadv_priv *bat_priv, struct sk_buff *skb,
+			   __be32 ip_src, __be32 ip_dst, u8 *hw_src,
+			   unsigned short vid, unsigned int arp_len)
+{
+	struct batadv_dat_candidate *cands;
+	bool self_is_candidate = false;
+	bool ret;
+
+	cands = batadv_dat_select_candidates(bat_priv, ip_dst, vid,
+					     &self_is_candidate);
+	if (!cands)
+		return false;
+
+	if (self_is_candidate) {
+		ret = batadv_dat_dht_get_self_reply(bat_priv, ip_src, ip_dst,
+						    hw_src, vid, arp_len);
+		if (ret)
+			goto skip_remote_forward;
+	}
+
+	ret = batadv_dat_forward_data(bat_priv, cands, skb, ip_dst, vid,
+				      BATADV_P_DAT_DHT_GET);
+
+skip_remote_forward:
+	batadv_dat_candidates_free(cands);
 	return ret;
 }
 
@@ -965,19 +1247,57 @@ static void batadv_dat_tvlv_ogm_handler_v1(struct batadv_priv *bat_priv,
 }
 
 /**
- * batadv_dat_hash_free() - free the local DAT hash table
- * @bat_priv: the bat priv with all the mesh interface information
+ * batadv_dat_hash_free() - free a DAT hash table
+ * @hash: the hash table to free
  */
-static void batadv_dat_hash_free(struct batadv_priv *bat_priv)
+static void batadv_dat_hash_free(struct batadv_hashtable **hash)
 {
-	if (!bat_priv->dat.hash)
+	if (!(*hash))
 		return;
 
-	__batadv_dat_purge(bat_priv, NULL);
+	__batadv_dat_purge(*hash, NULL);
 
-	batadv_hash_destroy(bat_priv->dat.hash);
+	batadv_hash_destroy(*hash);
 
-	bat_priv->dat.hash = NULL;
+	*hash = NULL;
+}
+
+/**
+ * batadv_dat_cache_hash_init() - initialise the DAT cache hash table
+ * @bat_priv: the bat priv with all the mesh interface information
+ *
+ * Return: 0 in case of success, a negative error code otherwise
+ */
+static int batadv_dat_cache_hash_init(struct batadv_priv *bat_priv)
+{
+	if (bat_priv->dat.cache_hash)
+		return 0;
+
+	bat_priv->dat.cache_hash = batadv_hash_new(1024);
+
+	if (!bat_priv->dat.cache_hash)
+		return -ENOMEM;
+
+	return 0;
+}
+
+/**
+ * batadv_dat_dht_hash_init() - initialise the DAT DHT hash table
+ * @bat_priv: the bat priv with all the mesh interface information
+ *
+ * Return: 0 in case of success, a negative error code otherwise
+ */
+static int batadv_dat_dht_hash_init(struct batadv_priv *bat_priv)
+{
+	if (bat_priv->dat.dht_hash)
+		return 0;
+
+	bat_priv->dat.dht_hash = batadv_hash_new(1024);
+
+	if (!bat_priv->dat.dht_hash)
+		return -ENOMEM;
+
+	return 0;
 }
 
 /**
@@ -988,13 +1308,15 @@ static void batadv_dat_hash_free(struct batadv_priv *bat_priv)
  */
 int batadv_dat_init(struct batadv_priv *bat_priv)
 {
-	if (bat_priv->dat.hash)
-		return 0;
+	int ret;
 
-	bat_priv->dat.hash = batadv_hash_new(1024);
+	ret = batadv_dat_cache_hash_init(bat_priv);
+	if (ret < 0)
+		return ret;
 
-	if (!bat_priv->dat.hash)
-		return -ENOMEM;
+	ret = batadv_dat_dht_hash_init(bat_priv);
+	if (ret < 0)
+		return ret;
 
 	INIT_DELAYED_WORK(&bat_priv->dat.work, batadv_dat_purge);
 	batadv_dat_start_timer(bat_priv);
@@ -1017,23 +1339,25 @@ void batadv_dat_free(struct batadv_priv *bat_priv)
 
 	disable_delayed_work_sync(&bat_priv->dat.work);
 
-	batadv_dat_hash_free(bat_priv);
+	batadv_dat_hash_free(&bat_priv->dat.cache_hash);
+	batadv_dat_hash_free(&bat_priv->dat.dht_hash);
 }
 
 /**
- * batadv_dat_cache_dump_entry() - dump one entry of the DAT cache table to a
- *  netlink socket
+ * batadv_dat_dump_entry() - dump one entry of a DAT hash table to a netlink
+ *  socket
  * @msg: buffer for the message
  * @portid: netlink port
  * @cb: Control block containing additional options
  * @dat_entry: entry to dump
+ * @cmd: generic netlink command
  *
  * Return: 0 or error code.
  */
 static int
-batadv_dat_cache_dump_entry(struct sk_buff *msg, u32 portid,
-			    struct netlink_callback *cb,
-			    struct batadv_dat_entry *dat_entry)
+batadv_dat_dump_entry(struct sk_buff *msg, u32 portid,
+		      struct netlink_callback *cb,
+		      struct batadv_dat_entry *dat_entry, u8 cmd)
 {
 	u8 mac[ETH_ALEN] __aligned(2);
 	u64 u64_mac;
@@ -1041,8 +1365,7 @@ batadv_dat_cache_dump_entry(struct sk_buff *msg, u32 portid,
 	void *hdr;
 
 	hdr = genlmsg_put(msg, portid, cb->nlh->nlmsg_seq,
-			  &batadv_netlink_family, NLM_F_MULTI,
-			  BATADV_CMD_GET_DAT_CACHE);
+			  &batadv_netlink_family, NLM_F_MULTI, cmd);
 	if (!hdr)
 		return -ENOBUFS;
 
@@ -1066,22 +1389,23 @@ batadv_dat_cache_dump_entry(struct sk_buff *msg, u32 portid,
 }
 
 /**
- * batadv_dat_cache_dump_bucket() - dump one bucket of the DAT cache table to
- *  a netlink socket
+ * batadv_dat_dump_bucket() - dump one bucket of a DAT hash table to a netlink
+ *  socket
  * @msg: buffer for the message
  * @portid: netlink port
  * @cb: Control block containing additional options
  * @hash: hash to dump
  * @bucket: bucket index to dump
  * @idx_skip: How many entries to skip
+ * @cmd: generic netlink command
  *
  * Return: 0 or error code.
  */
 static int
-batadv_dat_cache_dump_bucket(struct sk_buff *msg, u32 portid,
-			     struct netlink_callback *cb,
-			     struct batadv_hashtable *hash, unsigned int bucket,
-			     int *idx_skip)
+batadv_dat_dump_bucket(struct sk_buff *msg, u32 portid,
+		       struct netlink_callback *cb,
+		       struct batadv_hashtable *hash, unsigned int bucket,
+		       int *idx_skip, u8 cmd)
 {
 	struct batadv_dat_entry *dat_entry;
 	int idx = 0;
@@ -1093,7 +1417,7 @@ batadv_dat_cache_dump_bucket(struct sk_buff *msg, u32 portid,
 		if (idx < *idx_skip)
 			goto skip;
 
-		if (batadv_dat_cache_dump_entry(msg, portid, cb, dat_entry)) {
+		if (batadv_dat_dump_entry(msg, portid, cb, dat_entry, cmd)) {
 			spin_unlock_bh(&hash->list_locks[bucket]);
 			*idx_skip = idx;
 
@@ -1109,30 +1433,26 @@ batadv_dat_cache_dump_bucket(struct sk_buff *msg, u32 portid,
 }
 
 /**
- * batadv_dat_cache_dump() - dump DAT cache table to a netlink socket
+ * batadv_dat_dump() - dump a DAT hash table to a netlink socket
+ * @bat_priv: the bat priv with all the mesh interface information
  * @msg: buffer for the message
  * @cb: callback structure containing arguments
+ * @hash: the hash table to dump from
+ * @cmd: generic netlink command
  *
  * Return: message length.
  */
-int batadv_dat_cache_dump(struct sk_buff *msg, struct netlink_callback *cb)
+static int
+batadv_dat_dump(struct batadv_priv *bat_priv, struct sk_buff *msg,
+		struct netlink_callback *cb, struct batadv_hashtable *hash,
+		u8 cmd)
 {
-	struct batadv_hard_iface *primary_if = NULL;
 	int portid = NETLINK_CB(cb->skb).portid;
-	struct net_device *mesh_iface;
-	struct batadv_hashtable *hash;
-	struct batadv_priv *bat_priv;
+	struct batadv_hard_iface *primary_if;
 	int bucket = cb->args[0];
 	int idx = cb->args[1];
 	int ret = 0;
 
-	mesh_iface = batadv_netlink_get_meshif(cb);
-	if (IS_ERR(mesh_iface))
-		return PTR_ERR(mesh_iface);
-
-	bat_priv = netdev_priv(mesh_iface);
-	hash = bat_priv->dat.hash;
-
 	primary_if = batadv_primary_if_get_selected(bat_priv);
 	if (!primary_if || primary_if->if_status != BATADV_IF_ACTIVE) {
 		ret = -ENOENT;
@@ -1140,8 +1460,8 @@ int batadv_dat_cache_dump(struct sk_buff *msg, struct netlink_callback *cb)
 	}
 
 	while (bucket < hash->size) {
-		if (batadv_dat_cache_dump_bucket(msg, portid, cb, hash, bucket,
-						 &idx))
+		if (batadv_dat_dump_bucket(msg, portid, cb, hash, bucket, &idx,
+					   cmd))
 			break;
 
 		bucket++;
@@ -1156,8 +1476,58 @@ int batadv_dat_cache_dump(struct sk_buff *msg, struct netlink_callback *cb)
 out:
 	batadv_hardif_put(primary_if);
 
+	return ret;
+}
+
+/**
+ * batadv_dat_cache_dump() - dump the DAT cache table to a netlink socket
+ * @msg: buffer for the message
+ * @cb: callback structure containing arguments
+ *
+ * Return: Message length on success or a negative error number otherwise.
+ */
+int batadv_dat_cache_dump(struct sk_buff *msg, struct netlink_callback *cb)
+{
+	struct net_device *mesh_iface;
+	struct batadv_priv *bat_priv;
+	int ret;
+
+	mesh_iface = batadv_netlink_get_meshif(cb);
+	if (IS_ERR(mesh_iface))
+		return PTR_ERR(mesh_iface);
+
+	bat_priv = netdev_priv(mesh_iface);
+
+	ret = batadv_dat_dump(bat_priv, msg, cb, bat_priv->dat.cache_hash,
+			      BATADV_CMD_GET_DAT_CACHE);
+
 	dev_put(mesh_iface);
+	return ret;
+}
 
+/**
+ * batadv_dat_dht_dump() - dump the DAT DHT table to a netlink socket
+ * @msg: buffer for the message
+ * @cb: callback structure containing arguments
+ *
+ * Return: Message length on success or a negative error number otherwise.
+ */
+int batadv_dat_dht_dump(struct sk_buff *msg, struct netlink_callback *cb)
+{
+	struct net_device *mesh_iface;
+	struct batadv_priv *bat_priv;
+	int ret;
+
+	mesh_iface = batadv_netlink_get_meshif(cb);
+	if (IS_ERR(mesh_iface))
+		return PTR_ERR(mesh_iface);
+
+	bat_priv = netdev_priv(mesh_iface);
+
+	ret = batadv_dat_dump(bat_priv, msg, cb, bat_priv->dat.dht_hash,
+			      BATADV_CMD_GET_DAT_DHT);
+
+	dev_put(mesh_iface);
 	return ret;
 }
 
@@ -1330,9 +1700,9 @@ bool batadv_dat_snoop_outgoing_arp_request(struct batadv_priv *bat_priv,
 	hw_src = batadv_arp_hw_src(skb, hdr_size);
 	ip_dst = batadv_arp_ip_dst(skb, hdr_size);
 
-	batadv_dat_entry_add(bat_priv, ip_src, hw_src, vid);
+	batadv_dat_cache_entry_add(bat_priv, ip_src, hw_src, vid);
 
-	dat_entry = batadv_dat_entry_hash_find(bat_priv, ip_dst, vid);
+	dat_entry = batadv_dat_cache_entry_find(bat_priv, ip_dst, vid);
 	if (dat_entry) {
 		u64_mac = atomic64_read(&dat_entry->mac_addr);
 		u64_to_ether_addr(u64_mac, mac);
@@ -1341,12 +1711,13 @@ bool batadv_dat_snoop_outgoing_arp_request(struct batadv_priv *bat_priv,
 						hw_src, mac, vid, arp_len);
 		if (!rep)
 			batadv_dbg(BATADV_DBG_DAT, bat_priv,
-				   "ARP request replied locally\n");
+				   "ARP request for %pI4 replied locally (via DAT cache)\n",
+				   &ip_dst);
 		ret = (rep != -ENOMEM);
 	} else {
 		/* Send the request to the DHT */
-		ret = batadv_dat_forward_data(bat_priv, skb, ip_dst, vid,
-					      BATADV_P_DAT_DHT_GET);
+		ret = batadv_dat_forward_dht_get(bat_priv, skb, ip_src, ip_dst,
+						 hw_src, vid, arp_len);
 	}
 out:
 	batadv_dat_entry_put(dat_entry);
@@ -1401,9 +1772,9 @@ bool batadv_dat_snoop_incoming_arp_request(struct batadv_priv *bat_priv,
 
 	batadv_dbg_arp(bat_priv, skb, hdr_size, "Parsing incoming ARP REQUEST");
 
-	batadv_dat_entry_add(bat_priv, ip_src, hw_src, vid);
+	batadv_dat_cache_entry_add(bat_priv, ip_src, hw_src, vid);
 
-	dat_entry = batadv_dat_entry_hash_find(bat_priv, ip_dst, vid);
+	dat_entry = batadv_dat_dht_entry_find(bat_priv, ip_dst, vid);
 	if (!dat_entry)
 		goto out;
 
@@ -1470,16 +1841,14 @@ void batadv_dat_snoop_outgoing_arp_reply(struct batadv_priv *bat_priv,
 	hw_dst = batadv_arp_hw_dst(skb, hdr_size);
 	ip_dst = batadv_arp_ip_dst(skb, hdr_size);
 
-	batadv_dat_entry_add(bat_priv, ip_src, hw_src, vid);
-	batadv_dat_entry_add(bat_priv, ip_dst, hw_dst, vid);
+	batadv_dat_cache_entry_add(bat_priv, ip_src, hw_src, vid);
+	batadv_dat_cache_entry_add(bat_priv, ip_dst, hw_dst, vid);
 
 	/* Send the ARP reply to the candidates for both the IP addresses that
 	 * the node obtained from the ARP reply
 	 */
-	batadv_dat_forward_data(bat_priv, skb, ip_src, vid,
-				BATADV_P_DAT_DHT_PUT);
-	batadv_dat_forward_data(bat_priv, skb, ip_dst, vid,
-				BATADV_P_DAT_DHT_PUT);
+	batadv_dat_forward_dht_put(bat_priv, skb, ip_src, hw_src, vid);
+	batadv_dat_forward_dht_put(bat_priv, skb, ip_dst, hw_dst, vid);
 }
 
 /**
@@ -1488,6 +1857,8 @@ void batadv_dat_snoop_outgoing_arp_reply(struct batadv_priv *bat_priv,
  * @bat_priv: the bat priv with all the mesh interface information
  * @skb: packet to check
  * @hdr_size: size of the encapsulation header
+ * @is_dht_put: ARP reply is part of a unicast 4addr DHT PUT packet and should
+ *  not only update our local DAT cache but also our local DAT DHT
  *
  * Warning: This function may reallocate the skb data buffer via
  * batadv_dat_get_vid()/... Any pointer into the skb data (e.g. obtained
@@ -1498,7 +1869,8 @@ void batadv_dat_snoop_outgoing_arp_reply(struct batadv_priv *bat_priv,
  * packet has to be delivered to the interface
  */
 bool batadv_dat_snoop_incoming_arp_reply(struct batadv_priv *bat_priv,
-					 struct sk_buff *skb, int hdr_size)
+					 struct sk_buff *skb, int hdr_size,
+					 bool is_dht_put)
 {
 	struct batadv_dat_entry *dat_entry = NULL;
 	u8 mac[ETH_ALEN] __aligned(2);
@@ -1531,13 +1903,18 @@ bool batadv_dat_snoop_incoming_arp_reply(struct batadv_priv *bat_priv,
 	hw_dst = batadv_arp_hw_dst(skb, hdr_size);
 	ip_dst = batadv_arp_ip_dst(skb, hdr_size);
 
+	if (is_dht_put) {
+		batadv_dat_dht_entry_add(bat_priv, ip_src, hw_src, vid);
+		batadv_dat_dht_entry_add(bat_priv, ip_dst, hw_dst, vid);
+	}
+
 	/* If ip_dst is already in cache and has the right mac address,
 	 * drop this frame if this ARP reply is destined for us because it's
 	 * most probably an ARP reply generated by another node of the DHT.
 	 * We have most probably received already a reply earlier. Delivering
 	 * this frame would lead to doubled receive of an ARP reply.
 	 */
-	dat_entry = batadv_dat_entry_hash_find(bat_priv, ip_src, vid);
+	dat_entry = batadv_dat_cache_entry_find(bat_priv, ip_src, vid);
 	if (dat_entry) {
 		u64_mac = atomic64_read(&dat_entry->mac_addr);
 		u64_to_ether_addr(u64_mac, mac);
@@ -1554,8 +1931,8 @@ bool batadv_dat_snoop_incoming_arp_reply(struct batadv_priv *bat_priv,
 	/* Update our internal cache with both the IP addresses the node got
 	 * within the ARP reply
 	 */
-	batadv_dat_entry_add(bat_priv, ip_src, hw_src, vid);
-	batadv_dat_entry_add(bat_priv, ip_dst, hw_dst, vid);
+	batadv_dat_cache_entry_add(bat_priv, ip_src, hw_src, vid);
+	batadv_dat_cache_entry_add(bat_priv, ip_dst, hw_dst, vid);
 
 	if (dropped)
 		goto out;
@@ -1809,13 +2186,11 @@ static void batadv_dat_put_dhcp(struct batadv_priv *bat_priv, u8 *chaddr,
 
 	skb_set_network_header(skb, ETH_HLEN);
 
-	batadv_dat_entry_add(bat_priv, yiaddr, chaddr, vid);
-	batadv_dat_entry_add(bat_priv, ip_dst, hw_dst, vid);
+	batadv_dat_cache_entry_add(bat_priv, yiaddr, chaddr, vid);
+	batadv_dat_cache_entry_add(bat_priv, ip_dst, hw_dst, vid);
 
-	batadv_dat_forward_data(bat_priv, skb, yiaddr, vid,
-				BATADV_P_DAT_DHT_PUT);
-	batadv_dat_forward_data(bat_priv, skb, ip_dst, vid,
-				BATADV_P_DAT_DHT_PUT);
+	batadv_dat_forward_dht_put(bat_priv, skb, yiaddr, chaddr, vid);
+	batadv_dat_forward_dht_put(bat_priv, skb, ip_dst, hw_dst, vid);
 
 	consume_skb(skb);
 
@@ -1945,8 +2320,8 @@ void batadv_dat_snoop_incoming_dhcp_ack(struct batadv_priv *bat_priv,
 	ethhdr = (struct ethhdr *)(skb->data + hdr_size);
 	hw_src = ethhdr->h_source;
 
-	batadv_dat_entry_add(bat_priv, yiaddr, chaddr, vid);
-	batadv_dat_entry_add(bat_priv, ip_src, hw_src, vid);
+	batadv_dat_cache_entry_add(bat_priv, yiaddr, chaddr, vid);
+	batadv_dat_cache_entry_add(bat_priv, ip_src, hw_src, vid);
 
 	batadv_dbg(BATADV_DBG_DAT, bat_priv,
 		   "Snooped from incoming DHCPACK (server address): %pI4, %pM (vid: %i)\n",
@@ -1999,7 +2374,7 @@ bool batadv_dat_drop_broadcast_packet(struct batadv_priv *bat_priv,
 		goto out;
 
 	ip_dst = batadv_arp_ip_dst(forw_packet->skb, hdr_size);
-	dat_entry = batadv_dat_entry_hash_find(bat_priv, ip_dst, vid);
+	dat_entry = batadv_dat_cache_entry_find(bat_priv, ip_dst, vid);
 	/* check if the node already got this entry */
 	if (!dat_entry) {
 		batadv_dbg(BATADV_DBG_DAT, bat_priv,
diff --git a/net/batman-adv/distributed-arp-table.h b/net/batman-adv/distributed-arp-table.h
index e7b75e82eb1d..ad81b7db921e 100644
--- a/net/batman-adv/distributed-arp-table.h
+++ b/net/batman-adv/distributed-arp-table.h
@@ -31,7 +31,8 @@ bool batadv_dat_snoop_incoming_arp_request(struct batadv_priv *bat_priv,
 void batadv_dat_snoop_outgoing_arp_reply(struct batadv_priv *bat_priv,
 					 struct sk_buff *skb);
 bool batadv_dat_snoop_incoming_arp_reply(struct batadv_priv *bat_priv,
-					 struct sk_buff *skb, int hdr_size);
+					 struct sk_buff *skb, int hdr_size,
+					 bool is_dht_put);
 void batadv_dat_snoop_outgoing_dhcp_ack(struct batadv_priv *bat_priv,
 					struct sk_buff *skb,
 					__be16 proto,
@@ -74,6 +75,7 @@ batadv_dat_init_own_addr(struct batadv_priv *bat_priv,
 int batadv_dat_init(struct batadv_priv *bat_priv);
 void batadv_dat_free(struct batadv_priv *bat_priv);
 int batadv_dat_cache_dump(struct sk_buff *msg, struct netlink_callback *cb);
+int batadv_dat_dht_dump(struct sk_buff *msg, struct netlink_callback *cb);
 
 /**
  * batadv_dat_inc_counter() - increment the correct DAT packet counter
@@ -126,7 +128,8 @@ batadv_dat_snoop_outgoing_arp_reply(struct batadv_priv *bat_priv,
 
 static inline bool
 batadv_dat_snoop_incoming_arp_reply(struct batadv_priv *bat_priv,
-				    struct sk_buff *skb, int hdr_size)
+				    struct sk_buff *skb, int hdr_size,
+				    bool is_dht_put)
 {
 	return false;
 }
@@ -176,6 +179,12 @@ batadv_dat_cache_dump(struct sk_buff *msg, struct netlink_callback *cb)
 	return -EOPNOTSUPP;
 }
 
+static inline int
+batadv_dat_dht_dump(struct sk_buff *msg, struct netlink_callback *cb)
+{
+	return -EOPNOTSUPP;
+}
+
 static inline void batadv_dat_inc_counter(struct batadv_priv *bat_priv,
 					  u8 subtype)
 {
diff --git a/net/batman-adv/netlink.c b/net/batman-adv/netlink.c
index 1177b3ceaf03..5250c3d1805e 100644
--- a/net/batman-adv/netlink.c
+++ b/net/batman-adv/netlink.c
@@ -1498,6 +1498,12 @@ static const struct genl_small_ops batadv_netlink_ops[] = {
 		.flags = GENL_UNS_ADMIN_PERM,
 		.dumpit = batadv_dat_cache_dump,
 	},
+	{
+		.cmd = BATADV_CMD_GET_DAT_DHT,
+		.validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
+		.flags = GENL_UNS_ADMIN_PERM,
+		.dumpit = batadv_dat_dht_dump,
+	},
 	{
 		.cmd = BATADV_CMD_GET_MCAST_FLAGS,
 		.validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
@@ -1550,7 +1556,7 @@ struct genl_family batadv_netlink_family __ro_after_init = {
 	.small_ops = batadv_netlink_ops,
 	.n_small_ops = ARRAY_SIZE(batadv_netlink_ops),
 #if LINUX_VERSION_IS_GEQ(6, 1, 0) // UGLY_HACK_NEW
-	.resv_start_op = BATADV_CMD_SET_VLAN + 1,
+	.resv_start_op = BATADV_CMD_GET_DAT_DHT + 1,
 #endif // UGLY_HACK_STOP
 	.mcgrps = batadv_netlink_mcgrps,
 	.n_mcgrps = ARRAY_SIZE(batadv_netlink_mcgrps),
diff --git a/net/batman-adv/routing.c b/net/batman-adv/routing.c
index 6442f5d0cc93..5cf26e8b3257 100644
--- a/net/batman-adv/routing.c
+++ b/net/batman-adv/routing.c
@@ -1046,6 +1046,7 @@ int batadv_recv_unicast_packet(struct sk_buff *skb,
 	struct batadv_orig_node *orig_node = NULL;
 	int hdr_size = sizeof(*unicast_packet);
 	enum batadv_subtype subtype;
+	bool is_dht_put = false;
 	int ret = NET_RX_DROP;
 	u8 *orig_addr_gw;
 	u8 *orig_addr;
@@ -1105,6 +1106,8 @@ int batadv_recv_unicast_packet(struct sk_buff *skb,
 				orig_addr = unicast_4addr_packet->src;
 				orig_node = batadv_orig_hash_find(bat_priv,
 								  orig_addr);
+			} else if (subtype == BATADV_P_DAT_DHT_PUT) {
+				is_dht_put = true;
 			}
 		}
 
@@ -1112,7 +1115,7 @@ int batadv_recv_unicast_packet(struct sk_buff *skb,
 							  hdr_size))
 			goto rx_success;
 		if (batadv_dat_snoop_incoming_arp_reply(bat_priv, skb,
-							hdr_size))
+							hdr_size, is_dht_put))
 			goto rx_success;
 
 		batadv_dat_snoop_incoming_dhcp_ack(bat_priv, skb, hdr_size);
@@ -1353,7 +1356,7 @@ int batadv_recv_bcast_packet(struct sk_buff *skb,
 
 	if (batadv_dat_snoop_incoming_arp_request(bat_priv, skb, hdr_size))
 		goto rx_success;
-	if (batadv_dat_snoop_incoming_arp_reply(bat_priv, skb, hdr_size))
+	if (batadv_dat_snoop_incoming_arp_reply(bat_priv, skb, hdr_size, false))
 		goto rx_success;
 
 	batadv_dat_snoop_incoming_dhcp_ack(bat_priv, skb, hdr_size);
diff --git a/net/batman-adv/types.h b/net/batman-adv/types.h
index c19caa84e692..045727c3adc0 100644
--- a/net/batman-adv/types.h
+++ b/net/batman-adv/types.h
@@ -1211,8 +1211,11 @@ struct batadv_priv_dat {
 	/** @addr: node DAT address */
 	batadv_dat_addr_t addr;
 
-	/** @hash: hashtable representing the local ARP cache */
-	struct batadv_hashtable *hash;
+	/** @cache_hash: hashtable representing the local ARP cache */
+	struct batadv_hashtable *cache_hash;
+
+	/** @dht_hash: hashtable representing the local DAT DHT */
+	struct batadv_hashtable *dht_hash;
 
 	/** @work: work queue callback item for cache purging */
 	struct delayed_work work;
-- 
2.55.0