Re: [B.A.T.M.A.N.] [PATCH v5 2/6] batman-adv: speed up dat by snooping received ip traffic

[Simon Wunderlich <sw@simonwunderlich.de>]

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Hi Andreas,

as suggested by yourself and according to the discussion, please drop this 
patch from the patchset on the next resend. It may be better to resend it 
separately when the concerns are cleared.

Thanks!
    Simon

On Friday 10 June 2016 13:11:00 Andreas Pape wrote:
> Speeding up dat address lookup is achieved by snooping all incoming ip
> traffic. This especially increases the propability in bla setups that
> a gateway into a common backbone network already has a fitting dat entry
> to answer incoming ARP requests directly coming from the backbone
> network thus further reducing ARP traffic in the mesh.
> 
> Signed-off-by: Andreas Pape <apape@phoenixcontact.com>
> ---
>  net/batman-adv/distributed-arp-table.c |   55
> ++++++++++++++++++++++++++++++++ net/batman-adv/distributed-arp-table.h |  
>  9 +++++-
>  net/batman-adv/soft-interface.c        |    3 ++
>  3 files changed, 66 insertions(+), 1 deletions(-)
> 
> diff --git a/net/batman-adv/distributed-arp-table.c
> b/net/batman-adv/distributed-arp-table.c index b752f8d..998a4b8 100644
> --- a/net/batman-adv/distributed-arp-table.c
> +++ b/net/batman-adv/distributed-arp-table.c
> @@ -27,6 +27,7 @@
>  #include <linux/if_arp.h>
>  #include <linux/if_ether.h>
>  #include <linux/if_vlan.h>
> +#include <linux/ip.h>
>  #include <linux/in.h>
>  #include <linux/jiffies.h>
>  #include <linux/kernel.h>
> @@ -362,6 +363,60 @@ out:
>  		batadv_dat_entry_put(dat_entry);
>  }
> 
> +/**
> + * batadv_dat_entry_check - check and update a dat entry
> + * @bat_priv: the bat priv with all the soft interface information
> + * @skb: socket buffer
> + * @vid: VLAN identifier
> + *
> + * snoops incoming socket buffer for dat cache updates, if dat is enabled.
> + * Can be called from other modules.
> + */
> +void batadv_dat_entry_check(struct batadv_priv *bat_priv, struct sk_buff
> *skb, +			    unsigned short vid)
> +{
> +	struct vlan_ethhdr *vhdr = NULL, tmp_vhdr;
> +	struct ethhdr *ethhdr = NULL;
> +	struct iphdr *iphdr = NULL, tmp_iphdr;
> +
> +	if (!atomic_read(&bat_priv->distributed_arp_table))
> +		return;
> +
> +	ethhdr = eth_hdr(skb);
> +
> +	switch (ntohs(ethhdr->h_proto)) {
> +	case ETH_P_IP:
> +		iphdr = skb_header_pointer(skb, ETH_HLEN, sizeof(tmp_iphdr),
> +					   &tmp_iphdr);
> +		break;
> +	case ETH_P_8021Q:
> +		vhdr = skb_header_pointer(skb, 0, sizeof(tmp_vhdr),
> +					  &tmp_vhdr);
> +		if (!vhdr)
> +			return;
> +		if (ntohs(vhdr->h_vlan_encapsulated_proto) != ETH_P_IP)
> +			return;
> +		iphdr = skb_header_pointer(skb, sizeof(tmp_vhdr),
> +					   sizeof(tmp_iphdr),
> +					   &tmp_iphdr);
> +		break;
> +	}
> +
> +	if (!iphdr)
> +		return;
> +	/* don't add source address 0.0.0.0, which can occur during
> +	 * dhcp discover or request.
> +	 */
> +	if (ntohl(iphdr->saddr) == 0)
> +		return;
> +
> +	batadv_dbg(BATADV_DBG_DAT, bat_priv,
> +		   "Snooped IP address: %pI4 %pM (vid: %d)\n",
> +		   &iphdr->saddr, ethhdr->h_source,
> +		   BATADV_PRINT_VID(vid));
> +	batadv_dat_entry_add(bat_priv, iphdr->saddr, ethhdr->h_source, vid);
> +}
> +
>  #ifdef CONFIG_BATMAN_ADV_DEBUG
> 
>  /**
> diff --git a/net/batman-adv/distributed-arp-table.h
> b/net/batman-adv/distributed-arp-table.h index 813ecea..cf1b93c 100644
> --- a/net/batman-adv/distributed-arp-table.h
> +++ b/net/batman-adv/distributed-arp-table.h
> @@ -80,7 +80,8 @@ 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_seq_print_text(struct seq_file *seq, void *offset);
> -
> +void batadv_dat_entry_check(struct batadv_priv *bat_priv, struct sk_buff
> *skb, +			    unsigned short vid);
>  /**
>   * batadv_dat_inc_counter - increment the correct DAT packet counter
>   * @bat_priv: the bat priv with all the soft interface information
> @@ -173,6 +174,12 @@ static inline void batadv_dat_inc_counter(struct
> batadv_priv *bat_priv, {
>  }
> 
> +static inline
> +void batadv_dat_entry_check(struct batadv_priv *bat_priv, struct sk_buff
> *skb, +			    unsigned short vid)
> +{
> +}
> +
>  #endif /* CONFIG_BATMAN_ADV_DAT */
> 
>  #endif /* _NET_BATMAN_ADV_DISTRIBUTED_ARP_TABLE_H_ */
> diff --git a/net/batman-adv/soft-interface.c
> b/net/batman-adv/soft-interface.c index 81665b1..a86748f 100644
> --- a/net/batman-adv/soft-interface.c
> +++ b/net/batman-adv/soft-interface.c
> @@ -442,6 +442,9 @@ void batadv_interface_rx(struct net_device *soft_iface,
>  		goto dropped;
>  	}
> 
> +	/* Snoop incoming traffic for dat update */
> +	batadv_dat_entry_check(bat_priv, skb, vid);
> +
>  	/* skb->dev & skb->pkt_type are set here */
>  	skb->protocol = eth_type_trans(skb, soft_iface);
> 
> --
> 1.7.0.4
> 
> 
> 
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