From: Vicente Jimenez Aguilar <goo...@gmail.com> Date: Fri, 11 Nov 2016 21:20:18 +0100
> @@ -819,6 +820,12 @@ static bool icmp_unreach(struct sk_buff *skb) > /* fall through */ > case 0: > info = ntohs(icmph->un.frag.mtu); > + /* Handle weird case where next hop MTU is > + * equal to or exceeding dropped packet size > + */ > + old_mtu = ntohs(iph->tot_len); > + if (info >= old_mtu) > + info = old_mtu - 2; This isn't something the old code did. The old code behaved much differently. In the case where the new mtu was smaller than 68 or larger than the iph->tot_len value, it would do several things: 1) First it would check for a BSD 4.2 anomaly and subtract old_mtu by the IP header length. 2) Second, it would try to guess the intended MTU using the mtu_plateau table. I don't see any code where a subtraction by a fixed constant of 2 occurred. Nor can I figure out what that might accomplish. If you really want to do this, you have to docuement what this 2 means, what it is accomplishing, and why you have choosen to accomplish it this way. Thanks.
