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-rw-r--r--epan/dissectors/packet-ehdlc.c479
1 files changed, 479 insertions, 0 deletions
diff --git a/epan/dissectors/packet-ehdlc.c b/epan/dissectors/packet-ehdlc.c
new file mode 100644
index 00000000..ece5fabd
--- /dev/null
+++ b/epan/dissectors/packet-ehdlc.c
@@ -0,0 +1,479 @@
+/* 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, 0x01FF,
+ "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:
+ */
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