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authorGuy Harris <guy@alum.mit.edu>2018-01-10 12:16:30 -0800
committerGuy Harris <guy@alum.mit.edu>2018-01-10 20:17:10 +0000
commit37e364b2411a9bead0d35192f7f9bbb7d66bc775 (patch)
tree1e85d0df33e16cde8c28e208e02159e8d6b543d0 /epan/dissectors
parent182112c10de7ad8082f2fce02d714cb8fb8c7b27 (diff)
Improve handling of VOIP VLAN queries and replies.
For queries, there appear to be two different versions, one with a 2-byte value of some unknown type and one with a 1-byte value that appears to be an "appliance type" code followed by a 2-byte VLAN ID. For replies, there only appears to be a version with a 1-byte "appliance type" followed by a 2-byte VLAN ID, but handle a too-short payload. Also point to http://www.rhyshaden.com/cdp.htm in some comments. Change-Id: If1b476d5e6b23c7e0ba027835c6f0c84c8b723b7 Reviewed-on: https://code.wireshark.org/review/25249 Reviewed-by: Guy Harris <guy@alum.mit.edu>
Diffstat (limited to 'epan/dissectors')
-rw-r--r--epan/dissectors/packet-cdp.c83
1 files changed, 50 insertions, 33 deletions
diff --git a/epan/dissectors/packet-cdp.c b/epan/dissectors/packet-cdp.c
index 17bd381c47..c389e606e3 100644
--- a/epan/dissectors/packet-cdp.c
+++ b/epan/dissectors/packet-cdp.c
@@ -38,9 +38,13 @@
*
* and
*
- * http://www.cisco.com/c/en/us/support/docs/switches/catalyst-4500-series-switches/13414-103.html#cdp
+ * http://www.cisco.com/c/en/us/support/docs/switches/catalyst-4500-series-switches/13414-103.html#cdp
*
* for some more information on CDP version 2 (a superset of version 1).
+ *
+ * Also see
+ *
+ * http://www.rhyshaden.com/cdp.htm
*/
void proto_register_cdp(void);
@@ -577,52 +581,58 @@ dissect_cdp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
break;
case TYPE_VOIP_VLAN_REPLY:
+ tlvi = NULL;
if (tree) {
- if (length >= 7) {
- tlv_tree = proto_tree_add_subtree_format(cdp_tree, tvb, offset, length, ett_cdp_tlv, NULL,
- "VoIP VLAN Reply: %u", tvb_get_ntohs(tvb, offset + 5));
+ guint32 vlan_id;
+
+ tlv_tree = proto_tree_add_subtree(cdp_tree, tvb,
+ offset, length, ett_cdp_tlv, &tlvi,
+ "VoIP VLAN Reply");
+ proto_tree_add_item(tlv_tree, hf_cdp_tlvtype, tvb, offset + TLV_TYPE, 2, ENC_BIG_ENDIAN);
+ proto_tree_add_item(tlv_tree, hf_cdp_tlvlength, tvb, offset + TLV_LENGTH, 2, ENC_BIG_ENDIAN);
+ if (length == 6) {
+ /*
+ * XXX - this doesn't appear to happen, so report it
+ * as an error.
+ */
+ proto_tree_add_item(tlv_tree, hf_cdp_data, tvb, offset + 4, 2, ENC_NA);
} else {
/*
- * XXX - what are these? I've seen them in some captures;
- * they have a length of 6, and run up to the end of
- * the packet, so if we try to dissect it the same way
- * we dissect the 7-byte ones, we report a malformed
- * frame.
+ * XXX - the first byte appears to be a 1-byte
+ * "appliance type" code.
*/
- tlv_tree = proto_tree_add_subtree(cdp_tree, tvb,
- offset, length, ett_cdp_tlv, NULL, "VoIP VLAN Reply");
- }
- proto_tree_add_item(tlv_tree, hf_cdp_tlvtype, tvb, offset + TLV_TYPE, 2, ENC_BIG_ENDIAN);
- proto_tree_add_item(tlv_tree, hf_cdp_tlvlength, tvb, offset + TLV_LENGTH, 2, ENC_BIG_ENDIAN);
- proto_tree_add_item(tlv_tree, hf_cdp_data, tvb, offset + 4, 1, ENC_NA);
- if (length >= 7) {
- proto_tree_add_item(tlv_tree, hf_cdp_voice_vlan, tvb, offset + 5, 2, ENC_BIG_ENDIAN);
+ proto_tree_add_item(tlv_tree, hf_cdp_data, tvb, offset + 4, 1, ENC_NA);
+ proto_tree_add_item_ret_uint(tlv_tree, hf_cdp_voice_vlan, tvb, offset + 5, 2, ENC_BIG_ENDIAN, &vlan_id);
+ proto_item_append_text(tlvi, ": VLAN %u", vlan_id);
}
}
offset += length;
break;
case TYPE_VOIP_VLAN_QUERY:
+ tlvi = NULL;
if (tree) {
- if (length >= 7) {
- tlv_tree = proto_tree_add_subtree_format(cdp_tree, tvb, offset, length,
- ett_cdp_tlv, NULL, "VoIP VLAN Query: %u", tvb_get_ntohs(tvb, offset + 5));
+ guint32 vlan_id;
+
+ tlv_tree = proto_tree_add_subtree(cdp_tree, tvb,
+ offset, length, ett_cdp_tlv, &tlvi,
+ "VoIP VLAN Query");
+ proto_tree_add_item(tlv_tree, hf_cdp_tlvtype, tvb, offset + TLV_TYPE, 2, ENC_BIG_ENDIAN);
+ proto_tree_add_item(tlv_tree, hf_cdp_tlvlength, tvb, offset + TLV_LENGTH, 2, ENC_BIG_ENDIAN);
+ if (length == 6) {
+ /*
+ * This is some unknown value; it's typically 0x20 0x00,
+ * which, as a big-endian value, is not a VLAN ID, as
+ * VLAN IDs are 12 bits long.
+ */
+ proto_tree_add_item(tlv_tree, hf_cdp_data, tvb, offset + 4, 2, ENC_BIG_ENDIAN);
} else {
/*
- * XXX - what are these? I've seen them in some captures;
- * they have a length of 6, and run up to the end of
- * the packet, so if we try to dissect it the same way
- * we dissect the 7-byte ones, we report a malformed
- * frame.
+ * XXX - is this a 1-byte "appliance type" code?
*/
- tlv_tree = proto_tree_add_subtree(cdp_tree, tvb,
- offset, length, ett_cdp_tlv, NULL, "VoIP VLAN Query");
- }
- proto_tree_add_item(tlv_tree, hf_cdp_tlvtype, tvb, offset + TLV_TYPE, 2, ENC_BIG_ENDIAN);
- proto_tree_add_item(tlv_tree, hf_cdp_tlvlength, tvb, offset + TLV_LENGTH, 2, ENC_BIG_ENDIAN);
- proto_tree_add_item(tlv_tree, hf_cdp_data, tvb, offset + 4, 1, ENC_NA);
- if (length >= 7) {
- proto_tree_add_item(tlv_tree, hf_cdp_voice_vlan, tvb, offset + 5, 2, ENC_BIG_ENDIAN);
+ proto_tree_add_item(tlv_tree, hf_cdp_data, tvb, offset + 4, 1, ENC_NA);
+ proto_tree_add_item_ret_uint(tlv_tree, hf_cdp_voice_vlan, tvb, offset + 5, 2, ENC_BIG_ENDIAN, &vlan_id);
+ proto_item_append_text(tlvi, ": VLAN %u", vlan_id);
}
}
offset += length;
@@ -1123,6 +1133,13 @@ dissect_address_tlv(tvbuff_t *tvb, int offset, int length, proto_tree *tree)
}
}
if ((protocol_type == PROTO_TYPE_IEEE_802_2) && (protocol_length == 8) && (etypeid > 0)) {
+ /*
+ * See also:
+ *
+ * http://www.rhyshaden.com/cdp.htm
+ *
+ * where other Ethertypes are mentioned.
+ */
switch (etypeid) {
case ETHERTYPE_IPv6: