Re: [B.A.T.M.A.N.] [PATCHv2 2/7] batman-adv: speed up dat by snooping received ip traffic

[Sven Eckelmann <sven@narfation.org>]

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On Friday 26 February 2016 14:18:17 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>
> ---
[...]
>  	switch (ntohs(ethhdr->h_proto)) {
> +	case ETH_P_IP:
> +		iphdr = (struct iphdr *)(skb->data + ETH_HLEN);
> +		/* snoop incoming traffic for dat update using the source mac
> +		 * and source ip to speed up dat.
> +		 */
> +		batadv_dat_entry_check(bat_priv, iphdr->saddr,
> +				       ethhdr->h_source, vid);
> +		break;
>  	case ETH_P_8021Q:
>  		vhdr = (struct vlan_ethhdr *)skb->data;
> 
> -		if (vhdr->h_vlan_encapsulated_proto != ethertype)
> +		if (vhdr->h_vlan_encapsulated_proto != ethertype) {
> +			/* snoop incoming traffic for dat update also for vlan
> +			 * tagged frames.
> +			 */
> +			if (vhdr->h_vlan_encapsulated_proto == ETH_P_IP) {
> +				iphdr = (struct iphdr *)(vhdr +
> +						sizeof(struct vlan_ethhdr));
> +				batadv_dat_entry_check(bat_priv, iphdr->saddr,
> +						       vhdr->h_source, vid);
> +			}

Where is the code to check that there is enough data for the iphdr 
(pskb_may_pull)? Same question goes to Marek for his initial change in 
48628bb9419f ("batman-adv: softif bridge loop avoidance") that introduced the 
vhdr->vlan_ethhdr check

Kind regards,
	Sven

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