With this patch a node may additionally perform the dropping or unicasting behaviour for a link-local IPv4 and link-local-all-nodes IPv6 multicast packet, too.
The extra counter and BATADV_MCAST_WANT_ALL_UNSNOOPABLES flag is needed because with a future bridge snooping support integration a node with a bridge on top of its soft interface is not able to reliably detect its multicast listeners for IPv4 link-local and the IPv6 link-local-all-nodes addresses anymore (see RFC4541, section 2.1.2.2 and section 3).
Even though this new flag does make "no difference" now, it'll ensure a seamless integration of multicast bridge support without needing to break compatibility later.
Also note, that even with multicast bridge support it will need only one node with a bridge to disable optimizations for link-local IPv4 and IPv6-link-local-all-nodes multicast, resulting in flooding all these packets again. So the 224.0.0.x address range and the ff02::1 address will never be a safe choice for multicast streaming etc. if you do not control every node.
Signed-off-by: Linus Lüssing linus.luessing@web.de --- main.h | 1 + multicast.c | 49 ++++++++++++++++++++++++++++++++++++++++++++++++- packet.h | 9 +++++++++ soft-interface.c | 1 + types.h | 2 ++ 5 files changed, 61 insertions(+), 1 deletion(-)
diff --git a/main.h b/main.h index c98416e..d3d4000 100644 --- a/main.h +++ b/main.h @@ -172,6 +172,7 @@ enum batadv_uev_type { #include <linux/slab.h> #include <net/sock.h> /* struct sock */ #include <net/addrconf.h> /* ipv6 address stuff */ +#include <linux/ip.h> #include <net/rtnetlink.h> #include <linux/jiffies.h> #include <linux/seq_file.h> diff --git a/multicast.c b/multicast.c index 9da14b3..076b550 100644 --- a/multicast.c +++ b/multicast.c @@ -266,6 +266,44 @@ out: }
/** + * batadv_mcast_forw_mode_check_ipv4 - check for optimized forwarding potential + * @skb: the IPv4 packet to check + * @bat_priv: the bat priv with all the soft interface information + * + * Check whether the given IPv4 packet has the potential to + * be forwarded with a mode more optimal than classic flooding. + * + * If so then return 0. Otherwise -EINVAL is returned or -ENOMEM if we are + * out of memory. + */ +static int batadv_mcast_forw_mode_check_ipv4(struct sk_buff *skb, + struct batadv_priv *bat_priv) +{ + struct iphdr *iphdr; + + /* We might fail due to out-of-memory -> drop it */ + if (!pskb_may_pull(skb, sizeof(struct ethhdr) + sizeof(*iphdr))) + return -ENOMEM; + + iphdr = ip_hdr(skb); + + /* TODO: Implement Multicast Router Discovery (RFC4286), + * then allow scope > link local, too + */ + if (!ipv4_is_local_multicast(iphdr->daddr)) + return -EINVAL; + + /* With one bridge involved, we cannot be certain about + * link-local multicast listener announcements anymore + * (see RFC4541, section 2.1.2.2) + */ + if (atomic_read(&bat_priv->mcast.num_want_all_unsnoopables)) + return -EINVAL; + + return 0; +} + +/** * batadv_mcast_forw_mode_check_ipv6 - check for optimized forwarding potential * @skb: the IPv6 packet to check * @bat_priv: the bat priv with all the soft interface information @@ -298,7 +336,8 @@ static int batadv_mcast_forw_mode_check_ipv6(struct sk_buff *skb, * link-local-all-nodes multicast listener announcements anymore * (see RFC4541, section 3, paragraph 3) */ - if (ipv6_addr_is_ll_all_nodes(&ip6hdr->daddr)) + if (ipv6_addr_is_ll_all_nodes(&ip6hdr->daddr) && + atomic_read(&bat_priv->mcast.num_want_all_unsnoopables)) return -EINVAL;
return 0; @@ -327,6 +366,8 @@ static int batadv_mcast_forw_mode_check(struct sk_buff *skb, return -EINVAL;
switch (ntohs(ethhdr->h_proto)) { + case ETH_P_IP: + return batadv_mcast_forw_mode_check_ipv4(skb, bat_priv); case ETH_P_IPV6: return batadv_mcast_forw_mode_check_ipv6(skb, bat_priv); default: @@ -418,6 +459,9 @@ static void batadv_mcast_tvlv_ogm_handler_v1(struct batadv_priv *bat_priv, batadv_mcast_counter_update(BATADV_ORIG_CAPA_HAS_MCAST, &bat_priv->mcast.num_disabled, ~orig->capabilities, ~old_capabilities); + batadv_mcast_counter_update(BATADV_MCAST_WANT_ALL_UNSNOOPABLES, + &bat_priv->mcast.num_want_all_unsnoopables, + mcast_flags, orig->mcast_flags);
orig->mcast_flags = mcast_flags; } @@ -456,4 +500,7 @@ void batadv_mcast_purge_orig(struct batadv_orig_node *orig) batadv_mcast_counter_update(BATADV_ORIG_CAPA_HAS_MCAST, &bat_priv->mcast.num_disabled, ~BATADV_NO_FLAGS, ~orig->capabilities); + batadv_mcast_counter_update(BATADV_MCAST_WANT_ALL_UNSNOOPABLES, + &bat_priv->mcast.num_want_all_unsnoopables, + BATADV_NO_FLAGS, orig->mcast_flags); } diff --git a/packet.h b/packet.h index 00af710..e7416f6 100644 --- a/packet.h +++ b/packet.h @@ -91,6 +91,15 @@ enum batadv_icmp_packettype { BATADV_PARAMETER_PROBLEM = 12, };
+/** + * enum batadv_mcast_flags - flags for multicast capabilities and settings + * @BATADV_MCAST_WANT_ALL_UNSNOOPABLES: we want all packets destined for + * 224.0.0.0/24 or ff02::1 + */ +enum batadv_mcast_flags { + BATADV_MCAST_WANT_ALL_UNSNOOPABLES = BIT(0), +}; + /* tt data subtypes */ #define BATADV_TT_DATA_TYPE_MASK 0x0F
diff --git a/soft-interface.c b/soft-interface.c index 2104108..25eba64 100644 --- a/soft-interface.c +++ b/soft-interface.c @@ -686,6 +686,7 @@ static int batadv_softif_init_late(struct net_device *dev) bat_priv->mcast.flags = BATADV_UNINIT_FLAGS; atomic_set(&bat_priv->multicast_mode, 1); atomic_set(&bat_priv->mcast.num_disabled, 0); + atomic_set(&bat_priv->mcast.num_want_all_unsnoopables, 0); #endif atomic_set(&bat_priv->gw_mode, BATADV_GW_MODE_OFF); atomic_set(&bat_priv->gw_sel_class, 20); diff --git a/types.h b/types.h index 82502ed..d85924f 100644 --- a/types.h +++ b/types.h @@ -579,11 +579,13 @@ struct batadv_priv_dat { * @mla_list: list of multicast addresses we are currently announcing via TT * @flags: the flags we have last sent in our mcast tvlv * @num_disabled: number of nodes that have no mcast tvlv + * @num_want_all_unsnoopables: number of nodes wanting unsnoopable IP traffic */ struct batadv_priv_mcast { struct hlist_head mla_list; int flags; atomic_t num_disabled; + atomic_t num_want_all_unsnoopables; }; #endif