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

On 19 April 2013 15:38, Antonio Quartulli ordex@autistici.org wrote:

Hi Mihail,

On Mon, Apr 15, 2013 at 12:37:33PM +0300, Mihail Costea wrote:

[...]

...

+#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; \
• } \
• }

I think this define is pretty overkill..What about creating a function which only takes care of converting a generic DHT data in a string. Later you can invoke this function when you want to print an IPv4/6 using batadv_dbg.

Here is an example:

char *batadv_dat_data_to_str(struct batadv_dat_entry *dat_entry, const char *buf, size_t buf_len) { /* do something and put the string representation of the entry in the * buf, without exceeding buf_len. * Remember to use IS_ENABLED(CONFIG_IPV6) inside */

    return buf;

}

Then you can call it directly as parameter of a batdv_dbg function. E.g:

batadv_dbg(....," %s\n", batadv_dat_data_to_str(entry, buf, buf_len));

I think this approach would be better and easy to extend for future data types. If you like this approach, what do you think about sending a patch now to add this function to the current code?

This could work. buf could be a string with a given pattern inside (let's say %data, or something similar) that would be automatically converted to the right type (like %pI4, or %pI6c.

...

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 */
• }

+}

Either you mail client killed the tabs or this switch is not indented properly. Also, do you think it would be better to return 0 in case of unknown type? In this way we prevent any further operation on the data buffer.

It might be from my gmail. Next time I will send it with git send-email. Thanks.

...

+/**

• 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; }

Also here, I think it is a mail client problem at this point :) Did you send the patch using git send-email? It will take care of not ruining the text ;)

...

+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;

Why don't you check the type first? if dat_entry->type != ip_type then you can "continue;" and skip the memory check. If you don't do so you may do a memory check beyond the limit of dat_entry->data if it is smaller than ip_size.

Thanks. Didn't think about this case.

...

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);

Here you can use the "new function" I told you about at the beginning of the email.

...

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

Nice job so far!

My suggestion now is to send patch (1) for the new "data_to_str" function and then split this RFC in two patches: (2) generalise the dat_entry struct by introducing the type and data fields, with all the needed functions (3) introduce the IPv6 data type and the related function.

However, having patch (3) merged without a "user" would not make much sense. So I think it would be good for now to send patch (1) and (2) and then send (3) along with the "snooping patch" as soon as it is ready.

Thanks a lot!

Cheers,

-- Antonio Quartulli

..each of us alone is worth nothing.. Ernesto "Che" Guevara

Thanks for the advice. I will make the changes asap.

Mihail