This is merely a historical archive of years 2008-2021, before the migration to mailman3.
A maintained and still updated list archive can be found at https://lists.osmocom.org/hyperkitty/list/baseband-devel@lists.osmocom.org/.
Alex Badea vamposdecampos at gmail.comHack 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;