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packet-ehdlc: Decode details of XID messages 

We so far only dumped the XID as raw hex bytes.  Now we actually decode
the header and internal data structure of the XID.

Change-Id: I2901486222d84166291e071bc07cb82a2f480974
Reviewed-on: https://code.wireshark.org/review/18461
Petri-Dish: Michael Mann <mmann78@netscape.net>
Tested-by: Petri Dish Buildbot <buildbot-no-reply@wireshark.org>
Reviewed-by: Michael Mann <mmann78@netscape.net>
This commit is contained in:
Harald Welte 2016-10-22 14:42:58 +02:00 committed by Michael Mann
parent 3e82f423d9
commit 1e65231798
1 changed files with 88 additions and 11 deletions
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99
epan/dissectors/packet-ehdlc.c
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@ -47,6 +47,12 @@ static int hf_ehdlc_tei = -1;
static int hf_ehdlc_c_r = -1;
static int hf_ehdlc_xid_payload = -1;
static int hf_ehdlc_xid_win_tx = -1;
static int hf_ehdlc_xid_win_rx = -1;
static int hf_ehdlc_xid_ack_tmr_ms = -1;
static int hf_ehdlc_xid_format_id = -1;
static int hf_ehdlc_xid_group_id = -1;
static int hf_ehdlc_xid_len = -1;
static int hf_ehdlc_control = -1;
static int hf_ehdlc_p = -1;
@ -93,6 +99,7 @@ static const xdlc_cf_items ehdlc_cf_items_ext = {
/* Initialize the subtree pointers */
static gint ett_ehdlc = -1;
static gint ett_ehdlc_xid = -1;
static gint ett_ehdlc_control = -1;
enum {
@ -149,6 +156,54 @@ static guint8 sapi_from_csapi(guint8 csapi)
static dissector_handle_t sub_handles[SUB_MAX];
static int
dissect_ehdlc_xid(proto_tree *tree, tvbuff_t *tvb, guint base_offset, guint len)
{
guint offset = base_offset;
proto_item *ti;
proto_tree *xid_tree;
/* XID is formatted like ISO 8885, typically we see
* something like
* 82 format identifier
* 80 group identifier
* 00 09 length
* 07 01 05 Window Size Tx
* 09 01 04 Ack Timer (msec)
* 08 01 05 Window Size Rx */
ti = proto_tree_add_item(tree, hf_ehdlc_xid_payload,
tvb, offset, len, ENC_NA);
xid_tree = proto_item_add_subtree(ti, ett_ehdlc_xid);
proto_tree_add_item(xid_tree, hf_ehdlc_xid_format_id, tvb, offset++, 1, ENC_NA);
proto_tree_add_item(xid_tree, hf_ehdlc_xid_group_id, tvb, offset++, 1, ENC_NA);
proto_tree_add_item(xid_tree, hf_ehdlc_xid_len, tvb, offset, 2, ENC_BIG_ENDIAN);
offset += 2;
while (tvb_reported_length_remaining(tvb, offset) >= 2) {
guint8 iei = tvb_get_guint8(tvb, offset++);
guint8 ie_len = tvb_get_guint8(tvb, offset++);
switch (iei) {
case 0x07:
proto_tree_add_item(xid_tree, hf_ehdlc_xid_win_tx, tvb,
offset, ie_len, ENC_NA);
break;
case 0x08:
proto_tree_add_item(xid_tree, hf_ehdlc_xid_win_rx, tvb,
offset, ie_len, ENC_NA);
break;
case 0x09:
proto_tree_add_item(xid_tree, hf_ehdlc_xid_ack_tmr_ms, tvb,
offset, ie_len, ENC_NA);
break;
}
offset += ie_len;
}
return offset - base_offset;
}
/* Code to actually dissect the packets */
static int
dissect_ehdlc(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
@ -239,17 +294,8 @@ dissect_ehdlc(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U
break;
}
} else if (control == (XDLC_U | XDLC_XID)) {
/* XID is formatted like ISO 8885, typically we see
* something like
* 82 format identifier
* 80 group identifier
* 00 09 length
* 07 01 05 Window Size Tx
* 09 01 04 Ack Timer (msec)
* 08 01 05 Window Size Rx */
proto_tree_add_item(ehdlc_tree, hf_ehdlc_xid_payload,
tvb, offset+header_length,
len-header_length, ENC_NA);
dissect_ehdlc_xid(ehdlc_tree, tvb, offset+header_length,
len-header_length);
}
if (len == 0)
@ -299,6 +345,36 @@ proto_register_ehdlc(void)
FT_BYTES, BASE_NONE, NULL, 0,
NULL, HFILL }
},
{ &hf_ehdlc_xid_win_tx,
{ "Transmit Window", "ehdlc.xid.win_tx",
FT_UINT8, BASE_DEC, NULL, 0,
NULL, HFILL }
},
{ &hf_ehdlc_xid_win_rx,
{ "Receive Window", "ehdlc.xid.win_rx",
FT_UINT8, BASE_DEC, NULL, 0,
NULL, HFILL }
},
{ &hf_ehdlc_xid_ack_tmr_ms,
{ "Timer (ms)", "ehdlc.xid.ack_tmr_ms",
FT_UINT8, BASE_DEC, NULL, 0,
NULL, HFILL }
},
{ &hf_ehdlc_xid_format_id,
{ "Format Identifier", "ehdlc.xid.format_id",
FT_UINT8, BASE_HEX, NULL, 0,
NULL, HFILL }
},
{ &hf_ehdlc_xid_group_id,
{ "Group Identifier", "ehdlc.xid.group_id",
FT_UINT8, BASE_HEX, NULL, 0,
NULL, HFILL }
},
{ &hf_ehdlc_xid_len,
{ "XID Length", "ehdlc.xid.len",
FT_UINT16, BASE_DEC, NULL, 0,
NULL, HFILL }
},
{ &hf_ehdlc_control,
{ "Control Field", "ehdlc.control",
FT_UINT16, BASE_HEX, NULL, 0,
@ -368,6 +444,7 @@ proto_register_ehdlc(void)
static gint *ett[] = {
&ett_ehdlc,
&ett_ehdlc_xid,
&ett_ehdlc_control,
};