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--- tcpdump.h.orig Thu May 5 18:41:37 2005
+++ tcpdump.h Thu May 5 18:41:53 2005
@@ -179,7 +179,7 @@
}
/* This function determine the offset for the IP packet in an Ethernet frame */
-/* We handle two cases : straight Ethernet encapsulation or PPPoE encapsulation */
+/* We handle three cases : straight Ethernet, PPPoE, or .1q VLAN encapsulation */
/* Written by Yann Samama (ysamama@nortelnetworks.com) on july 18th, 2003 */
static int find_ip_eth(char* buf)
{
@@ -192,16 +192,19 @@
switch (eth_proto_type)
{
case ETHERTYPE_IPV6: /* it's pure IPv6 over ethernet */
- offset = 14;
- break;
+ /* FALLTHROUGH */
case ETHERTYPE_IP: /* it's pure IPv4 over ethernet */
- offset = 14;
+ offset = sizeof(struct ether_header);
break;
case ETHERTYPE_PPPOE_SESSION: /* it's a PPPoE session */
memcpy(&ppp_proto_type, buf+20, 2);
ppp_proto_type = ntohs(ppp_proto_type);
if (ppp_proto_type == 0x0021) /* it's IP over PPPoE */
offset = PPPOE_SIZE;
+ break;
+ case ETHERTYPE_VLAN:
+ offset = sizeof(struct ether_header) +
+ ETHER_VLAN_ENCAP_LEN;
break;
default: /* well, this is not an IP packet */
offset = -1;
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