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batman-adv: h_vlan_encapsulated_proto access refactoring

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In case of a VLAN tagged frame the ethhdr pointer is
moved forward by 4 bytes so that the offset of h_proto
in struct ethhdr matches the real
h_vlan_encapsulated_proto address in the skb. While this
trickery is correct it makes the code harder to understand
and may lead to bugs in case of re-use of ethhdr for other
purposes.

This patch introduces a proto variable to make things
cleaner and easier to understand.

Signed-off-by: Antonio Quartulli <ordex@autistici.org>
Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>
This commit is contained in:
Antonio Quartulli 2013-05-12 21:51:15 +02:00 committed by Antonio Quartulli
parent 2102605947
commit f7f8ed5695
1 changed files with 12 additions and 7 deletions
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19
net/batman-adv/gateway_client.c
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@ -655,24 +655,29 @@ bool batadv_gw_is_dhcp_target(struct sk_buff *skb, unsigned int *header_len)
struct iphdr *iphdr;
struct ipv6hdr *ipv6hdr;
struct udphdr *udphdr;
struct vlan_ethhdr *vhdr;
__be16 proto;
/* check for ethernet header */
if (!pskb_may_pull(skb, *header_len + ETH_HLEN))
return false;
ethhdr = (struct ethhdr *)skb->data;
proto = ethhdr->h_proto;
*header_len += ETH_HLEN;
/* check for initial vlan header */
if (ntohs(ethhdr->h_proto) == ETH_P_8021Q) {
if (proto == htons(ETH_P_8021Q)) {
if (!pskb_may_pull(skb, *header_len + VLAN_HLEN))
return false;
ethhdr = (struct ethhdr *)(skb->data + VLAN_HLEN);
vhdr = (struct vlan_ethhdr *)skb->data;
proto = vhdr->h_vlan_encapsulated_proto;
*header_len += VLAN_HLEN;
}
/* check for ip header */
switch (ntohs(ethhdr->h_proto)) {
case ETH_P_IP:
switch (proto) {
case htons(ETH_P_IP):
if (!pskb_may_pull(skb, *header_len + sizeof(*iphdr)))
return false;
iphdr = (struct iphdr *)(skb->data + *header_len);
@ -683,7 +688,7 @@ bool batadv_gw_is_dhcp_target(struct sk_buff *skb, unsigned int *header_len)
return false;
break;
case ETH_P_IPV6:
case htons(ETH_P_IPV6):
if (!pskb_may_pull(skb, *header_len + sizeof(*ipv6hdr)))
return false;
ipv6hdr = (struct ipv6hdr *)(skb->data + *header_len);
@ -710,11 +715,11 @@ bool batadv_gw_is_dhcp_target(struct sk_buff *skb, unsigned int *header_len)
*header_len += sizeof(*udphdr);
/* check for bootp port */
if ((ntohs(ethhdr->h_proto) == ETH_P_IP) &&
if ((proto == htons(ETH_P_IP)) &&
(ntohs(udphdr->dest) != 67))
return false;
if ((ntohs(ethhdr->h_proto) == ETH_P_IPV6) &&
if ((proto == htons(ETH_P_IPV6)) &&
(ntohs(udphdr->dest) != 547))
return false;