[B.A.T.M.A.N.] [RFCv3] batman-adv: Modified DAT structures and functions in order to support both IPv4 and IPv6

[Mihail Costea <mihail.costea90@gmail.com>]

Subject: [RFCv3] batman-adv: Modified DAT structures and functions in order
 to support both IPv4 and IPv6

Signed-off-by: Mihail Costea <mihail.costea90@gmail.com>
Signed-off-by: Stefan Popa <Stefan.A.Popa@intel.com>
Reviewed-by: Stefan Popa <Stefan.A.Popa@intel.com>

---

Removed the ugly debug function with 2 macros (one is to test if IPV6 is
enabled). I'm open the better ideas (the debug macro is used in 4 places
to reduce switch-cases).
Changed "if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)" to
"if IS_ENABLED(CONFIG_IPV6)".
Changed batadv_dat_entry ip member from unsigned char * to void * and renamed
it to data.
Use only one batadv_compare_dat function.

 distributed-arp-table.c |  255 +++++++++++++++++++++++++++++++++++++----------
 types.h                 |   24 ++++-
 2 files changed, 224 insertions(+), 55 deletions(-)

diff --git a/distributed-arp-table.c b/distributed-arp-table.c
index 3a3e1d8..5936563 100644
--- a/distributed-arp-table.c
+++ b/distributed-arp-table.c
@@ -20,6 +20,7 @@
 #include <linux/if_ether.h>
 #include <linux/if_arp.h>
 #include <net/arp.h>
+#include <net/ipv6.h>

 #include "main.h"
 #include "hash.h"
@@ -31,6 +32,61 @@
 #include "translation-table.h"
 #include "unicast.h"

+#ifdef CONFIG_BATMAN_ADV_DEBUG
+
+#if IS_ENABLED(CONFIG_IPV6)
+
+/* batadv_dat_dbg_ip - print similar debug message for IPv4 and IPv6.
+ * @bat_priv: the bat priv with all the soft interface information
+ * @ip_type: IPv4 / IPv6 address
+ * @format_prefix: format before IP field
+ * @format_suffix: format after IP field
+ *
+ * At list one variable parameter should be the IP itself, and it should
+ * be placed correctly based on format prefix and format suffix arguments.
+ */
+#define batadv_dat_dbg_ip(bat_priv, ip_type, format_prefix, \
+  format_suffix, ...) \
+ { \
+ switch (ip_type) { \
+ case BATADV_DAT_IPV4: \
+ batadv_dbg(BATADV_DBG_DAT, bat_priv, \
+   format_prefix "%pI4" format_suffix, \
+   __VA_ARGS__); \
+ break; \
+ case BATADV_DAT_IPV6: \
+ batadv_dbg(BATADV_DBG_DAT, bat_priv, \
+   format_prefix "%pI6c" format_suffix, \
+   __VA_ARGS__); \
+ break; \
+ } \
+ }
+
+#else
+
+#define batadv_dat_dbg_ip(bat_priv, ip_type, format_prefix, \
+  format_suffix, ...) \
+ { \
+ switch (ip_type) { \
+ case BATADV_DAT_IPV4: \
+ batadv_dbg(BATADV_DBG_DAT, bat_priv, \
+   format_prefix "%pI4" format_suffix, \
+   __VA_ARGS__); \
+ break; \
+ } \
+ }
+#endif
+
+#else
+
+static void batadv_dat_dbg_ip(struct batadv_priv *bat_priv,
+      uint8_t ip_type, char *format_prefix,
+      char *format_suffix, ...)
+{
+}
+
+#endif /* CONFIG_BATMAN_ADV_DEBUG */
+
 static void batadv_dat_purge(struct work_struct *work);

 /**
@@ -45,6 +101,19 @@ static void batadv_dat_start_timer(struct
batadv_priv *bat_priv)
 }

 /**
+ * batadv_dat_entry_free_ref_rcu - free a dat entry using its rcu
+ * @rcu: the dat entry rcu
+ */
+static void batadv_dat_entry_free_ref_rcu(struct rcu_head *rcu)
+{
+ struct batadv_dat_entry *dat_entry;
+
+ dat_entry = container_of(rcu, struct batadv_dat_entry, rcu);
+ kfree(dat_entry->data);
+ kfree(dat_entry);
+}
+
+/**
  * batadv_dat_entry_free_ref - decrement the dat_entry refcounter and possibly
  * free it
  * @dat_entry: the entry to free
@@ -52,7 +121,7 @@ static void batadv_dat_start_timer(struct
batadv_priv *bat_priv)
 static void batadv_dat_entry_free_ref(struct batadv_dat_entry *dat_entry)
 {
  if (atomic_dec_and_test(&dat_entry->refcount))
- kfree_rcu(dat_entry, rcu);
+ call_rcu(&dat_entry->rcu, batadv_dat_entry_free_ref_rcu);
 }

 /**
@@ -130,6 +199,26 @@ static void batadv_dat_purge(struct work_struct *work)
 }

 /**
+ * batadv_sizeof_ip - get sizeof IP based on its type (IPv4 / IPv6)
+ * @ip_type: type of IP address
+ *
+ * Returns sizeof IP, or sizeof IPv4 if ip_type is invalid.
+ */
+static size_t batadv_sizeof_ip(uint8_t ip_type)
+{
+ switch (ip_type) {
+ case BATADV_DAT_IPV4:
+ return sizeof(__be32);
+#if IS_ENABLED(CONFIG_IPV6)
+ case BATADV_DAT_IPV6:
+ return sizeof(struct in6_addr);
+#endif
+ default:
+ return sizeof(__be32); /* fallback to IPv4 */
+ }
+}
+
+/**
  * batadv_compare_dat - comparing function used in the local DAT hash table
  * @node: node in the local table
  * @data2: second object to compare the node to
@@ -138,10 +227,18 @@ static void batadv_dat_purge(struct work_struct *work)
  */
 static int batadv_compare_dat(const struct hlist_node *node, const void *data2)
 {
- const void *data1 = container_of(node, struct batadv_dat_entry,
- hash_entry);
+ struct batadv_dat_entry *dat_entry1 = container_of(node,
+ struct batadv_dat_entry, hash_entry);
+ struct batadv_dat_entry *dat_entry2 = container_of(data2,
+ struct batadv_dat_entry, data);
+ size_t ip_size;

- return (memcmp(data1, data2, sizeof(__be32)) == 0 ? 1 : 0);
+ if (dat_entry1->type != dat_entry2->type)
+ return 0;
+
+ ip_size = batadv_sizeof_ip(dat_entry1->type);
+ return (memcmp(dat_entry1->data, dat_entry2->data,
+       ip_size) == 0 ? 1 : 0);
 }

 /**
@@ -201,16 +298,19 @@ static __be32 batadv_arp_ip_dst(struct sk_buff
*skb, int hdr_size)
  * batadv_hash_dat - compute the hash value for an IP address
  * @data: data to hash
  * @size: size of the hash table
+ * @ip_type: type of IP address
  *
  * Returns the selected index in the hash table for the given data.
  */
-static uint32_t batadv_hash_dat(const void *data, uint32_t size)
+static uint32_t batadv_hash_dat(const void *data, uint32_t size,
+       uint8_t ip_type)
 {
  const unsigned char *key = data;
  uint32_t hash = 0;
- size_t i;
+ size_t i, ip_size;

- for (i = 0; i < 4; i++) {
+ ip_size = batadv_sizeof_ip(ip_type);
+ for (i = 0; i < ip_size; i++) {
  hash += key[i];
  hash += (hash << 10);
  hash ^= (hash >> 6);
@@ -223,31 +323,47 @@ static uint32_t batadv_hash_dat(const void
*data, uint32_t size)
  return hash % size;
 }

+static uint32_t batadv_hash_dat_ipv4(const void *data, uint32_t size)
+{
+ return batadv_hash_dat(data, size, BATADV_DAT_IPV4);
+}
+
+#if IS_ENABLED(CONFIG_IPV6)
+static uint32_t batadv_hash_dat_ipv6(const void *data, uint32_t size)
+{
+ return batadv_hash_dat(data, size, BATADV_DAT_IPV6);
+}
+#endif
+
 /**
  * batadv_dat_entry_hash_find - look for a given dat_entry in the local hash
  * table
  * @bat_priv: the bat priv with all the soft interface information
  * @ip: search key
+ * @ip_type: type of IP address
  *
  * Returns 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_priv *bat_priv, void *ip,
+   uint8_t ip_type)
 {
  struct hlist_head *head;
  struct batadv_dat_entry *dat_entry, *dat_entry_tmp = NULL;
  struct batadv_hashtable *hash = bat_priv->dat.hash;
  uint32_t index;
+ size_t ip_size;

  if (!hash)
  return NULL;

- index = batadv_hash_dat(&ip, hash->size);
+ ip_size = batadv_sizeof_ip(ip_type);
+ index = batadv_hash_dat(ip, hash->size, ip_type);
  head = &hash->table[index];

  rcu_read_lock();
  hlist_for_each_entry_rcu(dat_entry, head, hash_entry) {
- if (dat_entry->ip != ip)
+ if (memcmp(dat_entry->data, ip, ip_size))
  continue;

  if (!atomic_inc_not_zero(&dat_entry->refcount))
@@ -264,24 +380,28 @@ batadv_dat_entry_hash_find(struct batadv_priv
*bat_priv, __be32 ip)
 /**
  * batadv_dat_entry_add - add a new dat entry or update it if already exists
  * @bat_priv: the bat priv with all the soft interface information
- * @ip: ipv4 to add/edit
+ * @ip: IP to add/edit
+ * @ip_type: type of IP address
  * @mac_addr: mac address to assign to the given ipv4
  */
-static void batadv_dat_entry_add(struct batadv_priv *bat_priv, __be32 ip,
- uint8_t *mac_addr)
+static void batadv_dat_entry_add(struct batadv_priv *bat_priv, void *ip,
+ uint8_t ip_type, uint8_t *mac_addr)
 {
  struct batadv_dat_entry *dat_entry;
  int hash_added;
+ size_t ip_size;
+ batadv_hashdata_choose_cb choose;

- dat_entry = batadv_dat_entry_hash_find(bat_priv, ip);
+ dat_entry = batadv_dat_entry_hash_find(bat_priv, ip, ip_type);
  /* if this entry is already known, just update it */
  if (dat_entry) {
  if (!batadv_compare_eth(dat_entry->mac_addr, mac_addr))
  memcpy(dat_entry->mac_addr, mac_addr, ETH_ALEN);
  dat_entry->last_update = jiffies;
- batadv_dbg(BATADV_DBG_DAT, bat_priv,
-   "Entry updated: %pI4 %pM\n", &dat_entry->ip,
-   dat_entry->mac_addr);
+
+ batadv_dat_dbg_ip(bat_priv, ip_type, "Entry updated: ",
+  " %pM\n", dat_entry->data,
+  dat_entry->mac_addr);
  goto out;
  }

@@ -289,13 +409,30 @@ static void batadv_dat_entry_add(struct
batadv_priv *bat_priv, __be32 ip,
  if (!dat_entry)
  goto out;

- dat_entry->ip = ip;
+ ip_size = batadv_sizeof_ip(ip_type);
+ dat_entry->data = kmalloc(ip_size, GFP_ATOMIC);
+ if (!dat_entry->data)
+ goto out;
+ memcpy(dat_entry->data, ip, ip_size);
+ dat_entry->type = ip_type;
+
  memcpy(dat_entry->mac_addr, mac_addr, ETH_ALEN);
  dat_entry->last_update = jiffies;
  atomic_set(&dat_entry->refcount, 2);

+ switch (ip_type) {
+#if IS_ENABLED(CONFIG_IPV6)
+ case BATADV_DAT_IPV6:
+ choose = batadv_hash_dat_ipv6;
+ break;
+#endif
+ default:
+ choose = batadv_hash_dat_ipv4; /* IPv4 by default */
+ break;
+ }
+
  hash_added = batadv_hash_add(bat_priv->dat.hash, batadv_compare_dat,
-     batadv_hash_dat, &dat_entry->ip,
+     choose, dat_entry->data,
      &dat_entry->hash_entry);

  if (unlikely(hash_added != 0)) {
@@ -304,9 +441,8 @@ 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\n",
-   &dat_entry->ip, dat_entry->mac_addr);
-
+ batadv_dat_dbg_ip(bat_priv, ip_type, "New entry added: ", " %pM\n",
+  dat_entry->data, dat_entry->mac_addr);
 out:
  if (dat_entry)
  batadv_dat_entry_free_ref(dat_entry);
@@ -513,7 +649,8 @@ static void batadv_choose_next_candidate(struct
batadv_priv *bat_priv,
  * batadv_dat_select_candidates - select the nodes which the DHT message has to
  * be sent to
  * @bat_priv: the bat priv with all the soft interface information
- * @ip_dst: ipv4 to look up in the DHT
+ * @ip_dst: IP to look up in the DHT
+ * @ip_type: type of IP address
  *
  * 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
@@ -522,7 +659,8 @@ static void batadv_choose_next_candidate(struct
batadv_priv *bat_priv,
  * Returns the candidate array of size BATADV_DAT_CANDIDATE_NUM.
  */
 static struct batadv_dat_candidate *
-batadv_dat_select_candidates(struct batadv_priv *bat_priv, __be32 ip_dst)
+batadv_dat_select_candidates(struct batadv_priv *bat_priv, void *ip_dst,
+     uint8_t ip_type)
 {
  int select;
  batadv_dat_addr_t last_max = BATADV_DAT_ADDR_MAX, ip_key;
@@ -535,12 +673,11 @@ batadv_dat_select_candidates(struct batadv_priv
*bat_priv, __be32 ip_dst)
  if (!res)
  return NULL;

- ip_key = (batadv_dat_addr_t)batadv_hash_dat(&ip_dst,
-    BATADV_DAT_ADDR_MAX);
+ ip_key = (batadv_dat_addr_t)batadv_hash_dat(ip_dst, BATADV_DAT_ADDR_MAX,
+ ip_type);

- batadv_dbg(BATADV_DBG_DAT, bat_priv,
-   "dat_select_candidates(): IP=%pI4 hash(IP)=%u\n", &ip_dst,
-   ip_key);
+ batadv_dat_dbg_ip(bat_priv, ip_type, "dat_select_candidates(): IP=",
+  " hash(IP)=%u\n", ip_dst, ip_key);

  for (select = 0; select < BATADV_DAT_CANDIDATES_NUM; select++)
  batadv_choose_next_candidate(bat_priv, res, select, ip_key,
@@ -554,6 +691,7 @@ batadv_dat_select_candidates(struct batadv_priv
*bat_priv, __be32 ip_dst)
  * @bat_priv: the bat priv with all the soft interface information
  * @skb: payload to send
  * @ip: the DHT key
+ * @ip_type: type of IP address
  * @packet_subtype: unicast4addr packet subtype to use
  *
  * This function copies the skb with pskb_copy() and is sent as unicast packet
@@ -563,7 +701,7 @@ batadv_dat_select_candidates(struct batadv_priv
*bat_priv, __be32 ip_dst)
  * otherwise.
  */
 static bool batadv_dat_send_data(struct batadv_priv *bat_priv,
- struct sk_buff *skb, __be32 ip,
+ struct sk_buff *skb, void *ip, uint8_t ip_type,
  int packet_subtype)
 {
  int i;
@@ -573,11 +711,11 @@ static bool batadv_dat_send_data(struct
batadv_priv *bat_priv,
  struct sk_buff *tmp_skb;
  struct batadv_dat_candidate *cand;

- cand = batadv_dat_select_candidates(bat_priv, ip);
+ cand = batadv_dat_select_candidates(bat_priv, ip, ip_type);
  if (!cand)
  goto out;

- batadv_dbg(BATADV_DBG_DAT, bat_priv, "DHT_SEND for %pI4\n", &ip);
+ batadv_dat_dbg_ip(bat_priv, ip_type, "DHT_SEND for ", "\n", ip);

  for (i = 0; i < BATADV_DAT_CANDIDATES_NUM; i++) {
  if (cand[i].type == BATADV_DAT_CANDIDATE_NOT_FOUND)
@@ -693,8 +831,8 @@ int batadv_dat_cache_seq_print_text(struct
seq_file *seq, void *offset)
  goto out;

  seq_printf(seq, "Distributed ARP Table (%s):\n", net_dev->name);
- seq_printf(seq, "          %-7s          %-13s %5s\n", "IPv4", "MAC",
-   "last-seen");
+ seq_printf(seq, "                       %-26s %-15s %5s\n",
+   "IPv4/IPv6", "MAC", "last-seen");

  for (i = 0; i < hash->size; i++) {
  head = &hash->table[i];
@@ -707,9 +845,20 @@ int batadv_dat_cache_seq_print_text(struct
seq_file *seq, void *offset)
  last_seen_msecs = last_seen_msecs % 60000;
  last_seen_secs = last_seen_msecs / 1000;

- seq_printf(seq, " * %15pI4 %14pM %6i:%02i\n",
-   &dat_entry->ip, dat_entry->mac_addr,
-   last_seen_mins, last_seen_secs);
+ switch (dat_entry->type) {
+ case BATADV_DAT_IPV4:
+ seq_printf(seq, " * %-40pI4 %15pM %6i:%02i\n",
+   dat_entry->data, dat_entry->mac_addr,
+   last_seen_mins, last_seen_secs);
+ break;
+#if IS_ENABLED(CONFIG_IPV6)
+ case BATADV_DAT_IPV6:
+ seq_printf(seq, " * %-40pI6c %15pM %6i:%02i\n",
+   dat_entry->data, dat_entry->mac_addr,
+   last_seen_mins, last_seen_secs);
+ break;
+#endif
+ }
  }
  rcu_read_unlock();
  }
@@ -830,9 +979,10 @@ bool batadv_dat_snoop_outgoing_arp_request(struct
batadv_priv *bat_priv,
  hw_src = batadv_arp_hw_src(skb, 0);
  ip_dst = batadv_arp_ip_dst(skb, 0);

- batadv_dat_entry_add(bat_priv, ip_src, hw_src);
+ batadv_dat_entry_add(bat_priv, &ip_src, BATADV_DAT_IPV4, hw_src);

- dat_entry = batadv_dat_entry_hash_find(bat_priv, ip_dst);
+ dat_entry = batadv_dat_entry_hash_find(bat_priv, &ip_dst,
+       BATADV_DAT_IPV4);
  if (dat_entry) {
  skb_new = arp_create(ARPOP_REPLY, ETH_P_ARP, ip_src,
      bat_priv->soft_iface, ip_dst, hw_src,
@@ -851,8 +1001,9 @@ bool batadv_dat_snoop_outgoing_arp_request(struct
batadv_priv *bat_priv,
  batadv_dbg(BATADV_DBG_DAT, bat_priv, "ARP request replied locally\n");
  ret = true;
  } else {
- /* Send the request to the DHT */
- ret = batadv_dat_send_data(bat_priv, skb, ip_dst,
+ /* Send the request on the DHT */
+ ret = batadv_dat_send_data(bat_priv, skb, &ip_dst,
+   BATADV_DAT_IPV4,
    BATADV_P_DAT_DHT_GET);
  }
 out:
@@ -895,9 +1046,10 @@ bool
batadv_dat_snoop_incoming_arp_request(struct batadv_priv *bat_priv,
  batadv_dbg_arp(bat_priv, skb, type, hdr_size,
        "Parsing incoming ARP REQUEST");

- batadv_dat_entry_add(bat_priv, ip_src, hw_src);
+ batadv_dat_entry_add(bat_priv, &ip_src, BATADV_DAT_IPV4, hw_src);

- dat_entry = batadv_dat_entry_hash_find(bat_priv, ip_dst);
+ dat_entry = batadv_dat_entry_hash_find(bat_priv, &ip_dst,
+       BATADV_DAT_IPV4);
  if (!dat_entry)
  goto out;

@@ -956,14 +1108,16 @@ void batadv_dat_snoop_outgoing_arp_reply(struct
batadv_priv *bat_priv,
  hw_dst = batadv_arp_hw_dst(skb, 0);
  ip_dst = batadv_arp_ip_dst(skb, 0);

- batadv_dat_entry_add(bat_priv, ip_src, hw_src);
- batadv_dat_entry_add(bat_priv, ip_dst, hw_dst);
+ batadv_dat_entry_add(bat_priv, &ip_src, BATADV_DAT_IPV4, hw_src);
+ batadv_dat_entry_add(bat_priv, &ip_dst, BATADV_DAT_IPV4, hw_dst);

  /* Send the ARP reply to the candidates for both the IP addresses that
  * the node obtained from the ARP reply
  */
- batadv_dat_send_data(bat_priv, skb, ip_src, BATADV_P_DAT_DHT_PUT);
- batadv_dat_send_data(bat_priv, skb, ip_dst, BATADV_P_DAT_DHT_PUT);
+ batadv_dat_send_data(bat_priv, skb, &ip_src, BATADV_DAT_IPV4,
+     BATADV_P_DAT_DHT_PUT);
+ batadv_dat_send_data(bat_priv, skb, &ip_dst, BATADV_DAT_IPV4,
+     BATADV_P_DAT_DHT_PUT);
 }
 /**
  * batadv_dat_snoop_incoming_arp_reply - snoop the ARP reply and fill the local
@@ -998,8 +1152,8 @@ 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);
- batadv_dat_entry_add(bat_priv, ip_dst, hw_dst);
+ batadv_dat_entry_add(bat_priv, &ip_src, BATADV_DAT_IPV4, hw_src);
+ batadv_dat_entry_add(bat_priv, &ip_dst, BATADV_DAT_IPV4, hw_dst);

  /* if this REPLY is directed to a client of mine, let's deliver the
  * packet to the interface
@@ -1043,7 +1197,8 @@ bool batadv_dat_drop_broadcast_packet(struct
batadv_priv *bat_priv,
  goto out;

  ip_dst = batadv_arp_ip_dst(forw_packet->skb, bcast_len);
- dat_entry = batadv_dat_entry_hash_find(bat_priv, ip_dst);
+ dat_entry = batadv_dat_entry_hash_find(bat_priv, &ip_dst,
+       BATADV_DAT_IPV4);
  /* check if the node already got this entry */
  if (!dat_entry) {
  batadv_dbg(BATADV_DBG_DAT, bat_priv,
diff --git a/types.h b/types.h
index 5f542bd..5b820f6 100644
--- a/types.h
+++ b/types.h
@@ -961,17 +961,19 @@ struct batadv_algo_ops {
 };

 /**
- * struct batadv_dat_entry - it is a single entry of batman-adv ARP backend. It
- * is used to stored ARP entries needed for the global DAT cache
- * @ip: the IPv4 corresponding to this DAT/ARP entry
- * @mac_addr: the MAC address associated to the stored IPv4
+ * struct batadv_dat_entry - it is a single entry of batman-adv
ARP/NDP backend. It
+ * is used to stored ARP/NDP entries needed for the global DAT cache
+ * @data: the data corresponding to this DAT ARP/NDP entry
+ * @type: the type corresponding to this DAT ARP/NDP entry
+ * @mac_addr: the MAC address associated to the stored data
  * @last_update: time in jiffies when this entry was refreshed last time
  * @hash_entry: hlist node for batadv_priv_dat::hash
  * @refcount: number of contexts the object is used
  * @rcu: struct used for freeing in an RCU-safe manner
  */
 struct batadv_dat_entry {
- __be32 ip;
+ void *data;
+ uint8_t type;
  uint8_t mac_addr[ETH_ALEN];
  unsigned long last_update;
  struct hlist_node hash_entry;
@@ -980,6 +982,18 @@ struct batadv_dat_entry {
 };

 /**
+ * batadv_dat_types - types used in batadv_dat_entry for IP
+ * @BATADV_DAT_IPv4: IPv4 address type
+ * @BATADV_DAT_IPv6: IPv6 address type
+ */
+enum batadv_dat_types {
+ BATADV_DAT_IPV4,
+#if IS_ENABLED(CONFIG_IPV6)
+ BATADV_DAT_IPV6,
+#endif
+};
+
+/**
  * struct batadv_dat_candidate - candidate destination for DAT operations
  * @type: the type of the selected candidate. It can one of the following:
  *  - BATADV_DAT_CANDIDATE_NOT_FOUND
--
1.7.10.4