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If the packet inside the VLAN packet isn't an Ethernet packet - i.e., if 

the type/length field has a value 1500 or less, and thus is a length
field rather than an Ethernet type field - give the next dissector only
that many bytes, and put an entry in the VLAN protocol tree for the
padding.

svn path=/trunk/; revision=2629
This commit is contained in:
Guy Harris 2000-11-13 04:44:14 +00:00
parent 9e4caf9d56
commit 98c064911a
1 changed files with 60 additions and 9 deletions
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69
packet-vlan.c
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@ -1,7 +1,7 @@
/* packet-vlan.c
* Routines for VLAN 802.1Q ethernet header disassembly
*
* $Id: packet-vlan.c,v 1.21 2000/11/12 05:58:34 guy Exp $
* $Id: packet-vlan.c,v 1.22 2000/11/13 04:44:14 guy Exp $
*
* Ethereal - Network traffic analyzer
* By Gerald Combs <gerald@zing.org>
@ -47,6 +47,7 @@ static int hf_vlan_cfi = -1;
static int hf_vlan_id = -1;
static int hf_vlan_etype = -1;
static int hf_vlan_len = -1;
static int hf_vlan_trailer = -1;
static gint ett_vlan = -1;
@ -70,10 +71,14 @@ capture_vlan(const u_char *pd, int offset, packet_counts *ld ) {
}
static void
dissect_vlan(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree) {
proto_tree *ti, *vlan_tree = NULL;
dissect_vlan(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
{
proto_tree *ti;
guint16 tci,encap_proto;
tvbuff_t *next_tvb;
volatile gboolean is_802_2;
tvbuff_t *volatile next_tvb;
tvbuff_t *volatile trailer_tvb;
proto_tree *volatile vlan_tree;
CHECK_DISPLAY_AS_DATA(proto_vlan, tvb, pinfo, tree);
@ -90,6 +95,8 @@ dissect_vlan(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree) {
(tci >> 13), ((tci >> 12) & 1), (tci & 0xFFF));
}
vlan_tree = NULL;
if (tree) {
ti = proto_tree_add_item(tree, proto_vlan, tvb, 0, 4, FALSE);
vlan_tree = proto_item_add_subtree(ti, ett_vlan);
@ -100,12 +107,53 @@ dissect_vlan(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree) {
}
if ( encap_proto <= IEEE_802_3_MAX_LEN) {
/* Give the next dissector only 'length' number of bytes */
proto_tree_add_uint(vlan_tree, hf_vlan_len, tvb, 2, 2, encap_proto);
next_tvb = tvb_new_subset(tvb, 4, -1, -1); /* XXX - should TRY() like dissect_eth() */
if ( tvb_get_ntohs(next_tvb, 2) == 0xffff ) {
dissect_ipx(next_tvb, pinfo, tree);
} else {
TRY {
next_tvb = tvb_new_subset(tvb, 4, encap_proto, encap_proto);
trailer_tvb = tvb_new_subset(tvb, 4 + encap_proto, -1, -1);
}
CATCH2(BoundsError, ReportedBoundsError) {
next_tvb = tvb_new_subset(tvb, 4, -1, encap_proto);
}
ENDTRY;
/* Is there an 802.2 layer? I can tell by looking at the first 2
bytes after the VLAN header. If they are 0xffff, then what
follows the VLAN header is an IPX payload, meaning no 802.2.
(IPX/SPX is they only thing that can be contained inside a
straight 802.3 packet, so presumably the same applies for
Ethernet VLAN packets). A non-0xffff value means that there's an
802.2 layer inside the VLAN layer */
is_802_2 = TRUE;
TRY {
if (tvb_get_ntohs(next_tvb, 2) == 0xffff) {
is_802_2 = FALSE;
}
}
CATCH2(BoundsError, ReportedBoundsError) {
; /* do nothing */
}
ENDTRY;
if (is_802_2 ) {
/* 802.2 LLC */
dissect_llc(next_tvb, pinfo, tree);
} else {
dissect_ipx(next_tvb, pinfo, tree);
}
/* If there's some bytes left over, mark them. */
if (trailer_tvb && tree) {
int trailer_length;
const guint8 *ptr;
trailer_length = tvb_length(trailer_tvb);
if (trailer_length > 0) {
ptr = tvb_get_ptr(trailer_tvb, 0, trailer_length);
proto_tree_add_bytes(vlan_tree, hf_vlan_trailer, tvb, 4 + encap_proto,
trailer_length, ptr);
}
}
} else {
ethertype(encap_proto, tvb, 4, pinfo, tree, vlan_tree, hf_vlan_etype);
@ -130,7 +178,10 @@ proto_register_vlan(void)
VALS(etype_vals), 0x0, "Type" }},
{ &hf_vlan_len, {
"Length", "vlan.len", FT_UINT16, BASE_DEC,
NULL, 0x0, "Length" }}
NULL, 0x0, "Length" }},
{ &hf_vlan_trailer, {
"Trailer", "vlan.trailer", FT_BYTES, BASE_NONE,
NULL, 0x0, "VLAN Trailer" }}
};
static gint *ett[] = {
&ett_vlan,