forked from osmocom/wireshark
480 lines
12 KiB
C
480 lines
12 KiB
C
/* packet-ehdlc.c
|
|
* Routines for packet dissection of Ericsson HDLC as used in A-bis over IP
|
|
* Copyright 2010-2012, 2016 by Harald Welte <laforge@gnumonks.org>
|
|
*
|
|
* This code is based on pure educational guesses while looking at protocol
|
|
* traces, as there is no publicly available protocol description by Ericsson.
|
|
* Even the name is a guess, since it looks quite a bit like HDLC and is used
|
|
* by Ericsson, I called it EHDLC.
|
|
*
|
|
* Wireshark - Network traffic analyzer
|
|
* By Gerald Combs <gerald@wireshark.org>
|
|
* Copyright 1998 Gerald Combs
|
|
*
|
|
* SPDX-License-Identifier: GPL-2.0-or-later
|
|
*/
|
|
|
|
#include "config.h"
|
|
|
|
#include <epan/packet.h>
|
|
#include <epan/xdlc.h>
|
|
#include "packet-l2tp.h"
|
|
|
|
void proto_register_ehdlc(void);
|
|
void proto_reg_handoff_ehdlc(void);
|
|
|
|
/* Initialize the protocol and registered fields */
|
|
static int proto_ehdlc = -1;
|
|
|
|
static int hf_ehdlc_data_len = -1;
|
|
static int hf_ehdlc_csapi = -1;
|
|
static int hf_ehdlc_ctei = -1;
|
|
|
|
static int hf_ehdlc_sapi = -1;
|
|
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;
|
|
static int hf_ehdlc_f = -1;
|
|
static int hf_ehdlc_u_modifier_cmd = -1;
|
|
static int hf_ehdlc_u_modifier_resp = -1;
|
|
static int hf_ehdlc_ftype_s_u = -1;
|
|
|
|
static int hf_ehdlc_n_r = -1;
|
|
static int hf_ehdlc_n_s = -1;
|
|
static int hf_ehdlc_p_ext = -1;
|
|
static int hf_ehdlc_f_ext = -1;
|
|
static int hf_ehdlc_s_ftype = -1;
|
|
static int hf_ehdlc_ftype_i = -1;
|
|
static int hf_ehdlc_ftype_s_u_ext = -1;
|
|
|
|
static dissector_handle_t ehdlc_handle;
|
|
|
|
/* Used only for U frames */
|
|
static const xdlc_cf_items ehdlc_cf_items = {
|
|
NULL,
|
|
NULL,
|
|
&hf_ehdlc_p,
|
|
&hf_ehdlc_f,
|
|
NULL,
|
|
&hf_ehdlc_u_modifier_cmd,
|
|
&hf_ehdlc_u_modifier_resp,
|
|
NULL,
|
|
&hf_ehdlc_ftype_s_u
|
|
};
|
|
|
|
/* Used only for I and S frames */
|
|
static const xdlc_cf_items ehdlc_cf_items_ext = {
|
|
&hf_ehdlc_n_r,
|
|
&hf_ehdlc_n_s,
|
|
&hf_ehdlc_p_ext,
|
|
&hf_ehdlc_f_ext,
|
|
&hf_ehdlc_s_ftype,
|
|
NULL,
|
|
NULL,
|
|
&hf_ehdlc_ftype_i,
|
|
&hf_ehdlc_ftype_s_u_ext,
|
|
};
|
|
|
|
/* Initialize the subtree pointers */
|
|
static gint ett_ehdlc = -1;
|
|
static gint ett_ehdlc_xid = -1;
|
|
static gint ett_ehdlc_control = -1;
|
|
|
|
enum {
|
|
SUB_RSL,
|
|
SUB_OML,
|
|
SUB_TFP,
|
|
SUB_PGSL,
|
|
SUB_DATA,
|
|
|
|
SUB_MAX
|
|
};
|
|
|
|
/* Determine TEI from Compressed TEI */
|
|
static guint8 tei_from_ctei(guint8 ctei)
|
|
{
|
|
if (ctei < 12)
|
|
return ctei;
|
|
else
|
|
return 60 + (ctei - 12);
|
|
}
|
|
|
|
static guint8 c_r_from_csapi(guint8 csapi)
|
|
{
|
|
switch (csapi) {
|
|
case 1:
|
|
case 6:
|
|
return 1;
|
|
default:
|
|
return 0;
|
|
}
|
|
}
|
|
|
|
static guint8 sapi_from_csapi(guint8 csapi)
|
|
{
|
|
switch (csapi) {
|
|
case 0:
|
|
case 1: /* RSL */
|
|
return 0;
|
|
case 2: /* TFP */
|
|
return 10;
|
|
case 3: /* TFP */
|
|
return 11;
|
|
case 4: /* P-GSL */
|
|
return 12;
|
|
case 5:
|
|
case 6: /* OML */
|
|
return 62;
|
|
case 7:
|
|
default:
|
|
/* error! */
|
|
return 0;
|
|
}
|
|
}
|
|
|
|
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_)
|
|
{
|
|
int offset = 4;
|
|
|
|
col_set_str(pinfo->cinfo, COL_PROTOCOL, "EHDLC");
|
|
col_clear(pinfo->cinfo, COL_INFO);
|
|
|
|
while (tvb_reported_length_remaining(tvb, offset) > 0) {
|
|
proto_item *ti = NULL;
|
|
proto_tree *ehdlc_tree = NULL;
|
|
guint16 len, hdr2;
|
|
guint8 csapi, ctei, sapi, tei, c_r;
|
|
tvbuff_t *next_tvb;
|
|
guint16 control;
|
|
gboolean is_response = FALSE, is_extended = TRUE;
|
|
gint header_length = 2; /* Address + Length field */
|
|
|
|
hdr2 = tvb_get_guint16(tvb, offset, ENC_BIG_ENDIAN);
|
|
len = hdr2 & 0x1FF;
|
|
csapi = hdr2 >> 13;
|
|
sapi = sapi_from_csapi(csapi);
|
|
c_r = c_r_from_csapi(csapi);
|
|
ctei = (hdr2 >> 9) & 0xF;
|
|
tei = tei_from_ctei(ctei);
|
|
|
|
/* Add TEI to INFO column */
|
|
col_append_fstr(pinfo->cinfo, COL_INFO, " | TEI:%02u | ", tei);
|
|
col_set_fence(pinfo->cinfo, COL_INFO);
|
|
|
|
if (tree) {
|
|
/* Use MIN(...,...) in the following to prevent a premature */
|
|
/* exception before we try to dissect whatever is available. */
|
|
ti = proto_tree_add_protocol_format(tree, proto_ehdlc,
|
|
tvb, offset, MIN(len, tvb_captured_length_remaining(tvb,offset)),
|
|
"Ericsson HDLC protocol");
|
|
ehdlc_tree = proto_item_add_subtree(ti, ett_ehdlc);
|
|
|
|
proto_tree_add_item(ehdlc_tree, hf_ehdlc_csapi,
|
|
tvb, offset, 1, ENC_BIG_ENDIAN);
|
|
proto_tree_add_item(ehdlc_tree, hf_ehdlc_ctei,
|
|
tvb, offset, 1, ENC_BIG_ENDIAN);
|
|
ti = proto_tree_add_uint(ehdlc_tree, hf_ehdlc_c_r,
|
|
tvb, offset, 1, c_r);
|
|
proto_item_set_generated(ti);
|
|
ti = proto_tree_add_uint(ehdlc_tree, hf_ehdlc_sapi,
|
|
tvb, offset, 1, sapi);
|
|
proto_item_set_generated(ti);
|
|
ti = proto_tree_add_uint(ehdlc_tree, hf_ehdlc_tei,
|
|
tvb, offset, 1, tei);
|
|
proto_item_set_generated(ti);
|
|
proto_tree_add_item(ehdlc_tree, hf_ehdlc_data_len,
|
|
tvb, offset, 2, ENC_BIG_ENDIAN);
|
|
}
|
|
|
|
if (sapi == 10 || sapi == 11) {
|
|
/* Voice TRAU */
|
|
next_tvb = tvb_new_subset_length(tvb, offset+2, len-2);
|
|
call_dissector(sub_handles[SUB_TFP], next_tvb, pinfo, tree);
|
|
offset += len;
|
|
continue;
|
|
} else if (sapi == 12) {
|
|
/* GPRS TRAU */
|
|
next_tvb = tvb_new_subset_length(tvb, offset+2, len-2);
|
|
call_dissector(sub_handles[SUB_PGSL], next_tvb, pinfo, tree);
|
|
offset += len;
|
|
continue;
|
|
}
|
|
|
|
control = dissect_xdlc_control(tvb, offset+2, pinfo, ehdlc_tree, hf_ehdlc_control,
|
|
ett_ehdlc_control, &ehdlc_cf_items, &ehdlc_cf_items_ext,
|
|
NULL, NULL, is_response, is_extended, FALSE);
|
|
header_length += XDLC_CONTROL_LEN(control, is_extended);
|
|
|
|
if (XDLC_IS_INFORMATION(control)) {
|
|
next_tvb = tvb_new_subset_length(tvb, offset+header_length,
|
|
len-header_length);
|
|
|
|
switch (sapi) {
|
|
case 0:
|
|
/* len == 4 seems to be some kind of ACK */
|
|
if (len <= 4)
|
|
break;
|
|
call_dissector(sub_handles[SUB_RSL], next_tvb, pinfo, tree);
|
|
break;
|
|
case 62:
|
|
/* len == 4 seems to be some kind of ACK */
|
|
if (len <= 4)
|
|
break;
|
|
call_dissector(sub_handles[SUB_OML], next_tvb, pinfo, tree);
|
|
break;
|
|
default:
|
|
call_dissector(sub_handles[SUB_DATA], next_tvb, pinfo, tree);
|
|
break;
|
|
}
|
|
} else if (control == (XDLC_U | XDLC_XID)) {
|
|
dissect_ehdlc_xid(ehdlc_tree, tvb, offset+header_length,
|
|
len-header_length);
|
|
}
|
|
|
|
if (len == 0)
|
|
len = 1;
|
|
offset += len;
|
|
}
|
|
return tvb_captured_length(tvb);
|
|
}
|
|
|
|
void
|
|
proto_register_ehdlc(void)
|
|
{
|
|
static hf_register_info hf[] = {
|
|
{ &hf_ehdlc_data_len,
|
|
{ "DataLen", "ehdlc.data_len",
|
|
FT_UINT16, BASE_DEC, NULL, 0x1FF,
|
|
"The length of the data (in bytes)", HFILL }
|
|
},
|
|
{ &hf_ehdlc_csapi,
|
|
{ "Compressed SAPI", "ehdlc.csapi",
|
|
FT_UINT8, BASE_DEC, NULL, 0xE0,
|
|
NULL, HFILL}
|
|
},
|
|
{ &hf_ehdlc_ctei,
|
|
{ "Compressed TEI", "ehdlc.ctei",
|
|
FT_UINT8, BASE_DEC, NULL, 0x1E,
|
|
NULL, HFILL}
|
|
},
|
|
{ &hf_ehdlc_sapi,
|
|
{ "SAPI", "ehdlc.sapi",
|
|
FT_UINT8, BASE_DEC, NULL, 0,
|
|
NULL, HFILL }
|
|
},
|
|
{ &hf_ehdlc_tei,
|
|
{ "TEI", "ehdlc.tei",
|
|
FT_UINT8, BASE_DEC, NULL, 0,
|
|
NULL, HFILL }
|
|
},
|
|
{ &hf_ehdlc_c_r,
|
|
{ "C/R", "ehdlc.c_r",
|
|
FT_UINT8, BASE_DEC, NULL, 0,
|
|
NULL, HFILL }
|
|
},
|
|
|
|
{ &hf_ehdlc_xid_payload,
|
|
{ "XID Payload", "ehdlc.xid_payload",
|
|
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,
|
|
NULL, HFILL }
|
|
},
|
|
{ &hf_ehdlc_n_r,
|
|
{ "N(R)", "ehdlc.control.n_r",
|
|
FT_UINT16, BASE_DEC, NULL, XDLC_N_R_EXT_MASK,
|
|
NULL, HFILL }
|
|
},
|
|
{ &hf_ehdlc_n_s,
|
|
{ "N(S)", "ehdlc.control.n_s",
|
|
FT_UINT16, BASE_DEC, NULL, XDLC_N_S_EXT_MASK,
|
|
NULL, HFILL }
|
|
},
|
|
{ &hf_ehdlc_p,
|
|
{ "Poll", "ehdlc.control.p",
|
|
FT_BOOLEAN, 8, TFS(&tfs_set_notset), XDLC_P_F,
|
|
NULL, HFILL }
|
|
},
|
|
{ &hf_ehdlc_p_ext,
|
|
{ "Poll", "ehdlc.control.p",
|
|
FT_BOOLEAN, 16, TFS(&tfs_set_notset), XDLC_P_F_EXT,
|
|
NULL, HFILL }
|
|
},
|
|
{ &hf_ehdlc_f,
|
|
{ "Final", "ehdlc.control.f",
|
|
FT_BOOLEAN, 8, TFS(&tfs_set_notset), XDLC_P_F,
|
|
NULL, HFILL }
|
|
},
|
|
{ &hf_ehdlc_f_ext,
|
|
{ "Final", "ehdlc.control.f",
|
|
FT_BOOLEAN, 16, TFS(&tfs_set_notset), XDLC_P_F_EXT,
|
|
NULL, HFILL }
|
|
},
|
|
{ &hf_ehdlc_s_ftype,
|
|
{ "Supervisory frame type", "ehdlc.control.s_ftype",
|
|
FT_UINT16, BASE_HEX, VALS(stype_vals), XDLC_S_FTYPE_MASK,
|
|
NULL, HFILL }
|
|
},
|
|
{ &hf_ehdlc_u_modifier_cmd,
|
|
{ "Command", "ehdlc.control.u_modifier_cmd",
|
|
FT_UINT8, BASE_HEX, VALS(modifier_vals_cmd), XDLC_U_MODIFIER_MASK,
|
|
NULL, HFILL }
|
|
},
|
|
{ &hf_ehdlc_u_modifier_resp,
|
|
{ "Response", "ehdlc.control.u_modifier_resp",
|
|
FT_UINT8, BASE_HEX, VALS(modifier_vals_resp), XDLC_U_MODIFIER_MASK,
|
|
NULL, HFILL }
|
|
},
|
|
{ &hf_ehdlc_ftype_i,
|
|
{ "Frame Type", "ehdlc.control.ftype",
|
|
FT_UINT16, BASE_HEX, VALS(ftype_vals), XDLC_I_MASK,
|
|
NULL, HFILL }
|
|
},
|
|
{ &hf_ehdlc_ftype_s_u,
|
|
{ "Frame Type", "ehdlc.control.ftype",
|
|
FT_UINT8, BASE_HEX, VALS(ftype_vals), XDLC_S_U_MASK,
|
|
NULL, HFILL }
|
|
},
|
|
{ &hf_ehdlc_ftype_s_u_ext,
|
|
{ "Frame Type", "ehdlc.control.ftype",
|
|
FT_UINT16, BASE_HEX, VALS(ftype_vals), XDLC_S_U_MASK,
|
|
NULL, HFILL }
|
|
},
|
|
};
|
|
|
|
static gint *ett[] = {
|
|
&ett_ehdlc,
|
|
&ett_ehdlc_xid,
|
|
&ett_ehdlc_control,
|
|
};
|
|
|
|
proto_ehdlc =
|
|
proto_register_protocol("Ericsson HDLC",
|
|
"Ericsson HDLC as used in A-bis over IP", "ehdlc");
|
|
|
|
proto_register_field_array(proto_ehdlc, hf, array_length(hf));
|
|
proto_register_subtree_array(ett, array_length(ett));
|
|
|
|
ehdlc_handle = register_dissector("ehdlc", dissect_ehdlc, proto_ehdlc);
|
|
}
|
|
|
|
void
|
|
proto_reg_handoff_ehdlc(void)
|
|
{
|
|
sub_handles[SUB_RSL] = find_dissector_add_dependency("gsm_abis_rsl", proto_ehdlc);
|
|
sub_handles[SUB_OML] = find_dissector_add_dependency("gsm_abis_oml", proto_ehdlc);
|
|
sub_handles[SUB_TFP] = find_dissector_add_dependency("gsm_abis_tfp", proto_ehdlc);
|
|
sub_handles[SUB_PGSL] = find_dissector_add_dependency("gsm_abis_pgsl", proto_ehdlc);
|
|
sub_handles[SUB_DATA] = find_dissector("data");
|
|
|
|
dissector_add_for_decode_as("l2tp.pw_type", ehdlc_handle);
|
|
}
|
|
|
|
/*
|
|
* Editor modelines - https://www.wireshark.org/tools/modelines.html
|
|
*
|
|
* Local variables:
|
|
* c-basic-offset: 8
|
|
* tab-width: 8
|
|
* indent-tabs-mode: t
|
|
* End:
|
|
*
|
|
* vi: set shiftwidth=8 tabstop=8 noexpandtab:
|
|
* :indentSize=8:tabSize=8:noTabs=false:
|
|
*/
|