21 Nov
2010
21 Nov
'10
9:47 p.m.
Hack dissection of Cell Broadcast Service into LAPDm. First-Block payloads
are also dissected directly.
---
packet-lapdm.c | 164 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 163 insertions(+), 1 deletion(-)
diff --git a/epan/dissectors/packet-lapdm.c b/epan/dissectors/packet-lapdm.c
index dbeac85..e1d67b4 100644
--- a/epan/dissectors/packet-lapdm.c
+++ b/epan/dissectors/packet-lapdm.c
@@ -61,12 +61,25 @@
#include <epan/xdlc.h>
#include <epan/reassemble.h>
+#include <epan/asn1.h>
+#include "packet-gsm_map.h"
+#include "packet-gsm_sms.h"
+
static int proto_lapdm = -1;
static int hf_lapdm_address = -1;
static int hf_lapdm_ea = -1;
static int hf_lapdm_cr = -1;
static int hf_lapdm_sapi = -1;
static int hf_lapdm_lpd = -1;
+static int hf_lapdm_cb_lb = -1;
+static int hf_lapdm_cb_seq = -1;
+static int hf_lapdm_cbs_serial_gs = -1;
+static int hf_lapdm_cbs_serial_mcode = -1;
+static int hf_lapdm_cbs_serial_updnum = -1;
+static int hf_lapdm_cbs_msgid = -1;
+static int hf_lapdm_cbs_page_num = -1;
+static int hf_lapdm_cbs_page_cnt = -1;
+static int hf_lapdm_cbs_content = -1;
static int hf_lapdm_control = -1;
static int hf_lapdm_n_r = -1;
@@ -103,6 +116,8 @@ static gint ett_lapdm_control = -1;
static gint ett_lapdm_length = -1;
static gint ett_lapdm_fragment = -1;
static gint ett_lapdm_fragments = -1;
+static gint ett_lapdm_cbs_serial = -1;
+static gint ett_lapdm_cbs_dcs = -1;
static GHashTable *lapdm_fragment_table = NULL;
static GHashTable *lapdm_reassembled_table = NULL;
@@ -121,6 +136,12 @@ static gboolean reassemble_lapdm = TRUE;
#define LAPDM_CR 0x02 /* Command/Response bit */
#define LAPDM_EA 0x01 /* First Address Extension bit */
#define LAPDM_LPD 0x60 /* Link Protocol Discriminator */
+#define LAPDM_LPD_CB 0x20 /* Cell Broadcast LPD */
+#define LAPDM_CB_LB 0x10 /* Cell Broadcast Last Bit */
+#define LAPDM_CB_SEQ 0x0f /* Cell Broadcast sequence number */
+#define LAPDM_CBS_SERIAL_GS 0xc0 /* CBS Serial Number - Geographical Scope */
+#define LAPDM_CBS_SERIAL_MCODE 0x3ffc /* CBS Serial Number - Message Code */
+#define LAPDM_CBS_SERIAL_UPDNUM 0x03 /* CBS Serial Number - Update Number */
/*
* Bits in the length field.
@@ -132,6 +153,7 @@ static gboolean reassemble_lapdm = TRUE;
#define LAPDM_LEN_SHIFT 2
#define LAPDM_HEADER_LEN 3
+#define LAPDM_CB_HEADER_LEN 1
#define LAPDM_SAPI_RR_CC_MM 0
#define LAPDM_SAPI_SMS 3
@@ -179,6 +201,33 @@ static const value_string lapdm_el_vals[] = {
{ 0, NULL }
};
+/* 04.12 section 3.3.1 */
+static const value_string lapdm_lb_vals[] = {
+ { 0, "More blocks" },
+ { 1, "Last block" },
+ { 0, NULL }
+};
+
+/* 04.12 section 3.3.1 */
+static const value_string lapdm_seq_vals[] = {
+ { 0, "First block" },
+ { 1, "Second block" },
+ { 2, "Third block" },
+ { 3, "Fourth block" },
+ { 8, "First schedule block" },
+ { 15, "Null message" },
+ { 0, NULL }
+};
+
+/* 03.41 section 9.3.2.1 */
+static const value_string lapdm_serial_gs_vals[] = {
+ { 0, "Cell wide (immediate)" },
+ { 1, "PLMN wide" },
+ { 2, "Location Area wide" },
+ { 3, "Cell wide" },
+ { 0, NULL }
+};
+
static const fragment_items lapdm_frag_items = {
/* Fragment subtrees */
@@ -209,6 +258,79 @@ lapdm_defragment_init (void)
static void
+dissect_lapdm_cb(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
+{
+ proto_tree *lapdm_tree, *addr_tree;
+ proto_item *lapdm_ti, *addr_ti;
+ guint8 addr, seq;
+ tvbuff_t *payload;
+ int offset;
+ int length, out_len;
+ gchar msgbuf[88];
+
+ addr = tvb_get_guint8(tvb, 0);
+ if (tree) {
+ lapdm_ti = proto_tree_add_item(tree, proto_lapdm, tvb, 0, LAPDM_CB_HEADER_LEN,
FALSE);
+ lapdm_tree = proto_item_add_subtree(lapdm_ti, ett_lapdm);
+
+ addr_ti = proto_tree_add_uint(lapdm_tree, hf_lapdm_address, tvb, 0, 1, addr);
+ addr_tree = proto_item_add_subtree(addr_ti, ett_lapdm_address);
+
+ proto_tree_add_uint(addr_tree, hf_lapdm_lpd, tvb, 0, 1, addr);
+ proto_tree_add_uint(addr_tree, hf_lapdm_cb_lb, tvb, 0, 1, addr);
+ proto_tree_add_uint(addr_tree, hf_lapdm_cb_seq, tvb, 0, 1, addr);
+ } else {
+ lapdm_ti = NULL;
+ lapdm_tree = NULL;
+ }
+
+ col_append_str(pinfo->cinfo, COL_INFO, "CBS ");
+
+ offset = 1;
+
+ /* TODO: reassemble blocks 1-3 */
+ seq = addr & LAPDM_CB_SEQ;
+ if (seq == 0) {
+ proto_item *ti;
+ proto_tree *subtree;
+
+ ti = proto_tree_add_text(lapdm_tree, tvb, offset, 2, "Serial Number");
+ subtree = proto_item_add_subtree(ti, ett_lapdm_cbs_serial);
+
+ proto_tree_add_item(subtree, hf_lapdm_cbs_serial_gs, tvb, offset, 1, FALSE);
+ proto_tree_add_item(subtree, hf_lapdm_cbs_serial_mcode, tvb, offset, 2, FALSE);
+ offset++;
+ proto_tree_add_item(subtree, hf_lapdm_cbs_serial_updnum, tvb, offset, 1, FALSE);
+ offset++;
+
+ proto_tree_add_item(lapdm_tree, hf_lapdm_cbs_msgid, tvb, offset, 2, FALSE);
+ offset += 2;
+
+ ti = proto_tree_add_text(lapdm_tree, tvb, offset, 1, "Data Coding
Scheme");
+ subtree = proto_item_add_subtree(ti, ett_lapdm_cbs_dcs);
+ dissect_cbs_data_coding_scheme(tvb_new_subset(tvb, offset, 1, -1), pinfo,
subtree);
+ offset++;
+
+ proto_tree_add_item(lapdm_tree, hf_lapdm_cbs_page_num, tvb, offset, 1, FALSE);
+ proto_tree_add_item(lapdm_tree, hf_lapdm_cbs_page_cnt, tvb, offset, 1, FALSE);
+ offset++;
+
+ length = tvb_length(tvb) - offset;
+ out_len = gsm_sms_char_7bit_unpack(0, length, sizeof(msgbuf) - 1,
+ tvb_get_ptr(tvb, offset, length), msgbuf);
+ msgbuf[out_len] = '\0';
+ proto_tree_add_string(lapdm_tree, hf_lapdm_cbs_content, tvb, offset, length,
+ gsm_sms_chars_to_utf8(msgbuf, out_len));
+
+ col_append_fstr(pinfo->cinfo, COL_INFO, " [%s]",
gsm_sms_chars_to_utf8(msgbuf, out_len));
+ }
+
+ payload = tvb_new_subset_remaining(tvb, offset);
+ call_dissector(data_handle, payload, pinfo, tree);
+}
+
+
+static void
dissect_lapdm(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
{
proto_tree *lapdm_tree, *addr_tree, *length_tree;
@@ -227,6 +349,11 @@ dissect_lapdm(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
col_set_str(pinfo->cinfo, COL_PROTOCOL, "LAPDm");
addr = tvb_get_guint8(tvb, 0);
+ if ((addr & LAPDM_LPD) == LAPDM_LPD_CB) {
+ dissect_lapdm_cb(tvb, pinfo, tree);
+ return;
+ }
+
length = tvb_get_guint8(tvb, 2);
cr = addr & LAPDM_CR;
@@ -360,6 +487,39 @@ proto_register_lapdm(void)
{ "SAPI", "lapdm.sapi", FT_UINT8, BASE_DEC,
VALS(lapdm_sapi_vals), LAPDM_SAPI,
"Service access point identifier", HFILL }},
+ { &hf_lapdm_cb_lb,
+ { "LB", "lapdm.cb.lb", FT_UINT8, BASE_DEC,
+ VALS(lapdm_lb_vals), LAPDM_CB_LB, "Last Block bit", HFILL }},
+
+ { &hf_lapdm_cb_seq,
+ { "SEQ", "lapdm.cb.seq", FT_UINT8, BASE_DEC,
+ VALS(lapdm_seq_vals), LAPDM_CB_SEQ, "Sequence Number", HFILL }},
+
+ { &hf_lapdm_cbs_serial_gs,
+ { "GS", "lapdm.cbs.serial.gs", FT_UINT8, BASE_DEC,
+ VALS(lapdm_serial_gs_vals), LAPDM_CBS_SERIAL_GS, "Geographic Scope",
HFILL }},
+ { &hf_lapdm_cbs_serial_mcode,
+ { "Message Code", "lapdm.cbs.serial.mcode", FT_UINT16,
BASE_DEC,
+ NULL, LAPDM_CBS_SERIAL_MCODE, NULL, HFILL }},
+ { &hf_lapdm_cbs_serial_updnum,
+ { "Update Number", "lapdm.cbs.serial.updnum", FT_UINT8,
BASE_DEC,
+ NULL, LAPDM_CBS_SERIAL_MCODE, NULL, HFILL }},
+
+ { &hf_lapdm_cbs_msgid,
+ { "Message Identifier", "lapdm.cbs.msgid", FT_UINT16,
BASE_DEC,
+ NULL, 0, NULL, HFILL }},
+
+ { &hf_lapdm_cbs_page_num,
+ { "Page number", "lapdm.cbs.page.num", FT_UINT8, BASE_DEC,
+ NULL, 0xf0, NULL, HFILL }},
+ { &hf_lapdm_cbs_page_cnt,
+ { "Total pages", "lapdm.cbs.page.cnt", FT_UINT8, BASE_DEC,
+ NULL, 0x0f, NULL, HFILL }},
+
+ { &hf_lapdm_cbs_content,
+ { "Content of Message", "lapdm.cbs.content", FT_STRING,
BASE_NONE,
+ NULL, 0x00, NULL, HFILL }},
+
{ &hf_lapdm_control,
{ "Control Field", "lapdm.control_field", FT_UINT8, BASE_HEX,
NULL, 0x0,
NULL, HFILL }},
@@ -461,7 +621,9 @@ proto_register_lapdm(void)
&ett_lapdm_control,
&ett_lapdm_length,
&ett_lapdm_fragment,
- &ett_lapdm_fragments
+ &ett_lapdm_fragments,
+ &ett_lapdm_cbs_serial,
+ &ett_lapdm_cbs_dcs,
};
module_t *lapdm_module;