In case of an ARP message going in or out the soft_iface, it is intercepted and a special action is performed. In particular the DHT helper functions previously implemented are used to store all the ARP entries belonging to the network in order to provide a fast and unicast lookup instead of the classic broadcast flooding mechanism. Each node stores the entries it is responsible for (following the DHT rules) in its soft_iface ARP table. This makes it possible to reuse the kernel data structures and functions for ARP management.
Signed-off-by: Antonio Quartulli ordex@autistici.org --- distributed-arp-table.c | 271 ++++++++++++++++++++++++++++++++++++++++++++++- distributed-arp-table.h | 11 ++ main.h | 2 + routing.c | 31 +++++- send.c | 4 + soft-interface.c | 16 ++- 6 files changed, 330 insertions(+), 5 deletions(-)
diff --git a/distributed-arp-table.c b/distributed-arp-table.c index 9cac8af..2ece8be 100644 --- a/distributed-arp-table.c +++ b/distributed-arp-table.c @@ -19,6 +19,7 @@
#include <linux/if_ether.h> #include <linux/if_arp.h> +#include <net/arp.h>
#include "main.h" #include "hash.h" @@ -27,6 +28,7 @@ #include "originator.h" #include "send.h" #include "types.h" +#include "translation-table.h" #include "unicast.h"
static void batadv_dat_purge(struct work_struct *work); @@ -279,7 +281,7 @@ static void batadv_dat_entry_add(struct batadv_priv *bat_priv, __be32 ip, memcpy(dat_entry->mac_addr, mac_addr, ETH_ALEN); dat_entry->last_update = jiffies; batadv_dbg(BATADV_DBG_DAT, bat_priv, - "Update entry: %pI4 %pM\n", &dat_entry->ip, + "Entry updated: %pI4 %pM\n", &dat_entry->ip, dat_entry->mac_addr); goto out; } @@ -304,7 +306,7 @@ static void batadv_dat_entry_add(struct batadv_priv *bat_priv, __be32 ip, goto out; }
- batadv_dbg(BATADV_DBG_DAT, bat_priv, "Addin new entry: %pI4 %pM\n", + batadv_dbg(BATADV_DBG_DAT, bat_priv, "New entry added: %pI4 %pM\n", &dat_entry->ip, dat_entry->mac_addr);
out: @@ -800,3 +802,268 @@ static uint16_t batadv_arp_get_type(struct batadv_priv *bat_priv, out: return type; } + +/** + * batadv_dat_snoop_outgoing_arp_request - snoop the ARP request and try to + * answer using DAT + * @bat_priv: the bat priv with all the soft interface information + * @skb: packet to check + * + * Returns true if the message has been sent to the dht candidates, false + * otherwise. In case of true the message has to be enqueued to permit the + * fallback + */ +bool batadv_dat_snoop_outgoing_arp_request(struct batadv_priv *bat_priv, + struct sk_buff *skb) +{ + uint16_t type = 0; + __be32 ip_dst, ip_src; + uint8_t *hw_src; + bool ret = false; + struct batadv_dat_entry *dat_entry = NULL; + struct sk_buff *skb_new; + struct batadv_hard_iface *primary_if = NULL; + + type = batadv_arp_get_type(bat_priv, skb, 0); + /* If we get an ARP_REQUEST we have to send the unicast message to the + * selected DHT candidates + */ + if (type != ARPOP_REQUEST) + goto out; + + batadv_dbg_arp(bat_priv, skb, type, 0, "Parsing outgoing ARP REQUEST"); + + ip_src = batadv_arp_ip_src(skb, 0); + 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); + + dat_entry = batadv_dat_entry_hash_find(bat_priv, ip_dst); + /* check if it is a valid neigh entry */ + if (dat_entry) { + primary_if = batadv_primary_if_get_selected(bat_priv); + if (!primary_if) + goto out; + + skb_new = arp_create(ARPOP_REPLY, ETH_P_ARP, ip_src, + primary_if->soft_iface, ip_dst, hw_src, + dat_entry->mac_addr, hw_src); + if (!skb_new) + goto out; + + skb_reset_mac_header(skb_new); + skb_new->protocol = eth_type_trans(skb_new, + primary_if->soft_iface); + bat_priv->stats.rx_packets++; + bat_priv->stats.rx_bytes += skb->len + ETH_HLEN; + primary_if->soft_iface->last_rx = jiffies; + + netif_rx(skb_new); + batadv_dbg(BATADV_DBG_DAT, bat_priv, "ARP request replied locally\n"); + ret = true; + } else { + /* Send the request on the DHT */ + ret = batadv_dht_send_data(bat_priv, skb, ip_dst, + BATADV_P_DAT_DHT_GET); + } +out: + if (dat_entry) + batadv_dat_entry_free_ref(dat_entry); + if (primary_if) + batadv_hardif_free_ref(primary_if); + return ret; +} + +/** + * batadv_dat_snoop_incoming_arp_request - snoop the ARP request and try to + * answer using the local DAT storage + * @bat_priv: the bat priv with all the soft interface information + * @skb: packet to check + * @hdr_size: size of the encapsulation header + * + * Returns true if the request has been answered, false otherwise + */ +bool batadv_dat_snoop_incoming_arp_request(struct batadv_priv *bat_priv, + struct sk_buff *skb, int hdr_size) +{ + uint16_t type; + __be32 ip_src, ip_dst; + uint8_t *hw_src; + struct sk_buff *skb_new; + struct batadv_hard_iface *primary_if = NULL; + struct batadv_dat_entry *dat_entry = NULL; + bool ret = false; + int err; + + type = batadv_arp_get_type(bat_priv, skb, hdr_size); + if (type != ARPOP_REQUEST) + goto out; + + hw_src = batadv_arp_hw_src(skb, hdr_size); + ip_src = batadv_arp_ip_src(skb, hdr_size); + ip_dst = batadv_arp_ip_dst(skb, hdr_size); + + batadv_dbg_arp(bat_priv, skb, type, hdr_size, + "Parsing incoming ARP REQUEST"); + + batadv_dat_entry_add(bat_priv, ip_src, hw_src); + + dat_entry = batadv_dat_entry_hash_find(bat_priv, ip_dst); + /* check if it is a valid neigh entry */ + if (!dat_entry) + goto out; + + primary_if = batadv_primary_if_get_selected(bat_priv); + if (!primary_if) + goto out; + + skb_new = arp_create(ARPOP_REPLY, ETH_P_ARP, ip_src, + primary_if->soft_iface, ip_dst, hw_src, + dat_entry->mac_addr, hw_src); + + if (!skb_new) + goto out; + + /* to preserve backwards compatibility, here we have to answer using + * the same packet type we received for the request. This is due to + * that if a node is not using the 4addr packet format it may not + * support it. + */ + if (hdr_size == sizeof(struct batadv_unicast_4addr_packet)) + err = batadv_unicast_4addr_send_skb(skb_new, bat_priv, + BATADV_P_DAT_CACHE_REPLY); + else + err = batadv_unicast_send_skb(skb_new, bat_priv); + + if (!err) + ret = true; +out: + if (dat_entry) + batadv_dat_entry_free_ref(dat_entry); + if (primary_if) + batadv_hardif_free_ref(primary_if); + if (ret) + kfree_skb(skb); + return ret; +} + +/** + * batadv_dat_snoop_outgoing_arp_reply - snoop the ARP reply and fill the DHT + * @bat_priv: the bat priv with all the soft interface information + * @skb: packet to check + */ +void batadv_dat_snoop_outgoing_arp_reply(struct batadv_priv *bat_priv, + struct sk_buff *skb) +{ + uint16_t type; + __be32 ip_src, ip_dst; + uint8_t *hw_src, *hw_dst; + + type = batadv_arp_get_type(bat_priv, skb, 0); + if (type != ARPOP_REPLY) + return; + + batadv_dbg_arp(bat_priv, skb, type, 0, "Parsing outgoing ARP REPLY"); + + hw_src = batadv_arp_hw_src(skb, 0); + ip_src = batadv_arp_ip_src(skb, 0); + 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); + + /* Send the ARP reply to the candidates for both the IP addresses we + * fetched from the ARP reply + */ + batadv_dht_send_data(bat_priv, skb, ip_src, BATADV_P_DAT_DHT_PUT); + batadv_dht_send_data(bat_priv, skb, ip_dst, BATADV_P_DAT_DHT_PUT); +} +/** + * batadv_dat_snoop_incoming_arp_reply - snoop the ARP reply and fill the local + * DAT storage only + * @bat_priv: the bat priv with all the soft interface information + * @skb: packet to check + * @hdr_size: siaze of the encapsulation header + */ +bool batadv_dat_snoop_incoming_arp_reply(struct batadv_priv *bat_priv, + struct sk_buff *skb, int hdr_size) +{ + uint16_t type; + __be32 ip_src, ip_dst; + uint8_t *hw_src, *hw_dst; + bool ret = false; + + type = batadv_arp_get_type(bat_priv, skb, hdr_size); + if (type != ARPOP_REPLY) + goto out; + + batadv_dbg_arp(bat_priv, skb, type, hdr_size, + "Parsing incoming ARP REPLY"); + + hw_src = batadv_arp_hw_src(skb, hdr_size); + ip_src = batadv_arp_ip_src(skb, hdr_size); + hw_dst = batadv_arp_hw_dst(skb, hdr_size); + ip_dst = batadv_arp_ip_dst(skb, hdr_size); + + /* Update our internal cache with both the IP addresses we fetched from + * the ARP reply + */ + batadv_dat_entry_add(bat_priv, ip_src, hw_src); + batadv_dat_entry_add(bat_priv, ip_dst, hw_dst); + + /* if this REPLY is directed to a client of mine, let's deliver the + * packet to the interface + */ + ret = !batadv_is_my_client(bat_priv, hw_dst); +out: + /* if ret == false packet has to be delivered to the interface */ + return ret; +} + +/** + * batadv_dat_drop_broadcast_packet - check if an ARP request has to be dropped + * because we got the reply via DAT or not + * @bat_priv: the bat priv with all the soft interface information + * @forw_packet: the broadcast packet + * + * Returns true if we can drop the packet, false otherwise + */ +bool batadv_dat_drop_broadcast_packet(struct batadv_priv *bat_priv, + struct batadv_forw_packet *forw_packet) +{ + uint16_t type; + __be32 ip_dst; + struct batadv_dat_entry *dat_entry = NULL; + bool ret = false; + const size_t bcast_len = sizeof(struct batadv_bcast_packet); + + /* If this packet is an ARP_REQUEST and we already have the information + * that it is going to ask, we can drop the packet + */ + if (forw_packet->num_packets) + goto out; + + type = batadv_arp_get_type(bat_priv, forw_packet->skb, bcast_len); + if (type != ARPOP_REQUEST) + goto out; + + ip_dst = batadv_arp_ip_dst(forw_packet->skb, bcast_len); + dat_entry = batadv_dat_entry_hash_find(bat_priv, ip_dst); + /* check if we already know this neigh */ + if (!dat_entry) { + batadv_dbg(BATADV_DBG_DAT, bat_priv, + "ARP Request for %pI4: fallback\n", &ip_dst); + goto out; + } + + batadv_dbg(BATADV_DBG_DAT, bat_priv, + "ARP Request for %pI4: fallback prevented\n", &ip_dst); + ret = true; + +out: + if (dat_entry) + batadv_dat_entry_free_ref(dat_entry); + return ret; +} diff --git a/distributed-arp-table.h b/distributed-arp-table.h index 9096749..35c9f03 100644 --- a/distributed-arp-table.h +++ b/distributed-arp-table.h @@ -27,6 +27,17 @@
#define BATADV_DAT_ADDR_MAX ((batadv_dat_addr_t)~(batadv_dat_addr_t)0)
+bool batadv_dat_snoop_outgoing_arp_request(struct batadv_priv *bat_priv, + struct sk_buff *skb); +bool batadv_dat_snoop_incoming_arp_request(struct batadv_priv *bat_priv, + struct sk_buff *skb, int hdr_size); +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); +bool batadv_dat_drop_broadcast_packet(struct batadv_priv *bat_priv, + struct batadv_forw_packet *forw_packet); + static inline void batadv_dat_init_orig_node_dht_addr(struct batadv_orig_node *orig_node) { diff --git a/main.h b/main.h index d5aebcb..b4a4b4b 100644 --- a/main.h +++ b/main.h @@ -74,6 +74,8 @@
#define BATADV_LOG_BUF_LEN 8192 /* has to be a power of 2 */
+/* msecs after which an ARP_REQUEST is sent in broadcast as fallback */ +#define ARP_REQ_DELAY 250 /* numbers of originator to contact for any PUT/GET DHT operation */ #define DHT_CANDIDATES_NUM 3
diff --git a/routing.c b/routing.c index 191f531..785c926 100644 --- a/routing.c +++ b/routing.c @@ -28,6 +28,7 @@ #include "vis.h" #include "unicast.h" #include "bridge_loop_avoidance.h" +#include "distributed-arp-table.h"
static int batadv_route_unicast_packet(struct sk_buff *skb, struct batadv_hard_iface *recv_if); @@ -1014,11 +1015,13 @@ int batadv_recv_unicast_packet(struct sk_buff *skb, struct batadv_priv *bat_priv = netdev_priv(recv_if->soft_iface); struct batadv_unicast_packet *unicast_packet; int hdr_size = sizeof(*unicast_packet); + bool is4addr;
unicast_packet = (struct batadv_unicast_packet *)skb->data;
+ is4addr = unicast_packet->header.packet_type == BATADV_UNICAST_4ADDR; /* the caller function should have already pulled 2 bytes */ - if (unicast_packet->header.packet_type == BATADV_UNICAST_4ADDR) + if (is4addr) hdr_size = sizeof(struct batadv_unicast_4addr_packet);
if (batadv_check_unicast_packet(skb, hdr_size) < 0) @@ -1029,9 +1032,17 @@ int batadv_recv_unicast_packet(struct sk_buff *skb,
/* packet for me */ if (batadv_is_my_mac(unicast_packet->dest)) { + 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)) + goto rx_success; + batadv_interface_rx(recv_if->soft_iface, skb, recv_if, hdr_size, NULL);
+rx_success: return NET_RX_SUCCESS; }
@@ -1043,7 +1054,7 @@ int batadv_recv_ucast_frag_packet(struct sk_buff *skb, { struct batadv_priv *bat_priv = netdev_priv(recv_if->soft_iface); struct batadv_unicast_frag_packet *unicast_packet; - int hdr_size = sizeof(*unicast_packet); + int hdr_size = sizeof(struct batadv_unicast_packet); struct sk_buff *new_skb = NULL; int ret;
@@ -1067,8 +1078,17 @@ int batadv_recv_ucast_frag_packet(struct sk_buff *skb, if (!new_skb) return NET_RX_SUCCESS;
+ if (batadv_dat_snoop_incoming_arp_request(bat_priv, new_skb, + hdr_size)) + goto rx_success; + if (batadv_dat_snoop_incoming_arp_reply(bat_priv, skb, + hdr_size)) + goto rx_success; + batadv_interface_rx(recv_if->soft_iface, new_skb, recv_if, sizeof(struct batadv_unicast_packet), NULL); + +rx_success: return NET_RX_SUCCESS; }
@@ -1154,9 +1174,16 @@ int batadv_recv_bcast_packet(struct sk_buff *skb, if (batadv_bla_is_backbone_gw(skb, orig_node, hdr_size)) goto out;
+ 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)) + goto rx_success; + /* broadcast for me */ batadv_interface_rx(recv_if->soft_iface, skb, recv_if, hdr_size, orig_node); + +rx_success: ret = NET_RX_SUCCESS; goto out;
diff --git a/send.c b/send.c index 3b4b2da..c850124 100644 --- a/send.c +++ b/send.c @@ -18,6 +18,7 @@ */
#include "main.h" +#include "distributed-arp-table.h" #include "send.h" #include "routing.h" #include "translation-table.h" @@ -209,6 +210,9 @@ static void batadv_send_outstanding_bcast_packet(struct work_struct *work) if (atomic_read(&bat_priv->mesh_state) == BATADV_MESH_DEACTIVATING) goto out;
+ if (batadv_dat_drop_broadcast_packet(bat_priv, forw_packet)) + goto out; + /* rebroadcast packet */ rcu_read_lock(); list_for_each_entry_rcu(hard_iface, &batadv_hardif_list, list) { diff --git a/soft-interface.c b/soft-interface.c index 0080e6e..b881e34 100644 --- a/soft-interface.c +++ b/soft-interface.c @@ -20,6 +20,7 @@ #include "main.h" #include "soft-interface.h" #include "hard-interface.h" +#include "distributed-arp-table.h" #include "routing.h" #include "send.h" #include "debugfs.h" @@ -149,6 +150,7 @@ static int batadv_interface_tx(struct sk_buff *skb, int data_len = skb->len, ret; short vid __maybe_unused = -1; bool do_bcast = false; + unsigned long brd_delay = 1;
if (atomic_read(&bat_priv->mesh_state) != BATADV_MESH_ACTIVE) goto dropped; @@ -212,6 +214,13 @@ static int batadv_interface_tx(struct sk_buff *skb, if (!primary_if) goto dropped;
+ /* in case of ARP request, we do not immediately broadcasti the + * packet, instead we first wait for DAT to try to retrieve the + * correct ARP entry + */ + if (batadv_dat_snoop_outgoing_arp_request(bat_priv, skb)) + brd_delay = msecs_to_jiffies(ARP_REQ_DELAY); + if (batadv_skb_head_push(skb, sizeof(*bcast_packet)) < 0) goto dropped;
@@ -233,7 +242,7 @@ static int batadv_interface_tx(struct sk_buff *skb, bcast_packet->seqno = htonl(atomic_inc_return(&bat_priv->bcast_seqno));
- batadv_add_bcast_packet_to_list(bat_priv, skb, 1); + batadv_add_bcast_packet_to_list(bat_priv, skb, brd_delay);
/* a copy is stored in the bcast list, therefore removing * the original skb. @@ -248,6 +257,11 @@ static int batadv_interface_tx(struct sk_buff *skb, goto dropped; }
+ if (batadv_dat_snoop_outgoing_arp_request(bat_priv, skb)) + goto dropped; + + batadv_dat_snoop_outgoing_arp_reply(bat_priv, skb); + ret = batadv_unicast_send_skb(skb, bat_priv); if (ret != 0) goto dropped_freed;