Pablo Neira Ayuso wrote:
Jan Engelhardt wrote:
+static int dccp_pkt_to_tuple(const struct sk_buff *skb, unsigned int
dataoff,
+ struct nf_conntrack_tuple *tuple)
+{
+ struct dccp_hdr _hdr, *dh;
+
+ dh = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
+ if (dh == NULL)
+ return 0;
+
skb_header_pointer() is used for the case of a non-linear skb (has to
do with IP fragments?).
Indeed.
In ipv4_pkt_to_tuple in nf_conntrack_l3proto_ipv4.c,
skb_header_pointer() is used to get the [source address of the] IP
header. Since I figured the layer-3 header must always be
unfragmented, would not it be simpler to use ip_hdr(), or is there
something that mandates use of skb_header_pointer?
Right. I think that we can assume that the IP header is always linear (I
remember this from a conversation with Davem or Rusty), Patrick?
Right, the IP header is linearized by ip_rcv() (or bridge netfilter).
The pkt_to_tuple functions may be called for the inner packet of an
ICMP message however, which might be in the non-linear area.
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