Subject: Transforming code to using ICMP packet accessors

From: David Howells <[email-masked]>
Date: Thu, 26 Apr 2007 12:23:39 +0100

How do I convert:

	addr = *(__be32 *)(skb->nh.raw + serr->addr_offset);

to use the ICMP accessor macros now that skb->nh is no longer available?  I
was using this to pluck an address out of the ICMP packet payload, but 

	void rxrpc_UDP_error_report(struct sock *sk)
	{
		struct sock_exterr_skb *serr;
	...
		struct sk_buff *skb;
		__be32 addr;
		__be16 port;
	...

		skb = skb_dequeue(&sk->sk_error_queue);
		if (!skb) {
			_leave("UDP socket errqueue empty");
			return;
		}
	...

		serr = SKB_EXT_ERR(skb);
		addr = *(__be32 *)(skb->nh.raw + serr->addr_offset);
		port = serr->port;

		_net("Rx UDP Error from "NIPQUAD_FMT":%hu",
		     NIPQUAD(addr), ntohs(port));
	...
	}

Should I do this?:

	addr = *(__be32 *)(skb_network_header(skb) + serr->addr_offset);

David