Adding upstream version 4.2.2.upstream/4.2.2

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 579 insertions, 0 deletions

diff --git a/epan/dissectors/packet-lapdm.c b/epan/dissectors/packet-lapdm.c
new file mode 100644
index 00000000..91e3fc2c
--- /dev/null
+++ b/epan/dissectors/packet-lapdm.c
@@ -0,0 +1,579 @@
+/* packet-lapdm.c
+ * Routines for LAPDm frame disassembly
+ * Duncan Salerno <duncan.salerno@googlemail.com>
+ *
+ * Wireshark - Network traffic analyzer
+ * By Gerald Combs <gerald@wireshark.org>
+ * Copyright 1998
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+/* LAPDm references:
+ *
+ * Mobile Station - Base Stations System (MS - BSS) Interface Data Link (DL) Layer Specification
+ * Base Station Controller - Base Transceiver Station (BSC - BTS) interface; Layer 2 specification
+ * http://www.3gpp.org/ftp/Specs/html-info/44006.htm
+ *
+ * From 3GPP TS 44.006:
+ *
+ * LAPDm is used for information sent on the control channels BCCH, AGCH, NCH,
+ * PCH, FACCH, SACCH and SDCCH as defined in 3GPP TS 44.003.
+ *
+ * AGCH, NCH and PCH are sometimes referred to by the collective name CCCH.
+ * FACCH, SACCH and SDCCH are, similarly, referred to by the collective name DCCH.
+ *
+ * Format A is used on DCCHs for frames where there is no information field.
+ * Formats B, Bter and B4 are used on DCCHs for frames containing an information field:
+ * Format Bter is used on request of higher layers if and only if short L2 header type 1 is
+ * supported and a UI command is to be transmitted on SAPI 0;
+ * Format B4 is used for UI frames transmitted by the network on SACCH;
+ * Format B is applied in all other cases.
+ * Format Bbis is used only on BCCH, PCH, NCH, and AGCH.
+ * In addition there is a Format C for transmission of random access signals.
+ *
+ * This module currently supports A, B, B4
+ * In the future will support Bter
+ * Bbis and C should be supported elsewhere
+ */
+
+#include "config.h"
+#include "packet-lapdm.h"
+
+#include <epan/packet.h>
+#include <epan/prefs.h>
+#include <epan/xdlc.h>
+#include <epan/reassemble.h>
+#include <epan/conversation.h>
+
+void proto_register_lapdm(void);
+
+static dissector_handle_t b4_info_handle;
+
+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_control = -1;
+static int hf_lapdm_n_r = -1;
+static int hf_lapdm_n_s = -1;
+static int hf_lapdm_p = -1;
+static int hf_lapdm_f = -1;
+static int hf_lapdm_s_ftype = -1;
+static int hf_lapdm_u_modifier_cmd = -1;
+static int hf_lapdm_u_modifier_resp = -1;
+static int hf_lapdm_ftype_i = -1;
+static int hf_lapdm_ftype_s_u = -1;
+
+static int hf_lapdm_length = -1;
+static int hf_lapdm_el = -1;
+static int hf_lapdm_m = -1;
+static int hf_lapdm_len = -1;
+
+/*
+ * LAPDm fragment handling
+ */
+static int hf_lapdm_fragment_data = -1;
+static int hf_lapdm_fragments = -1;
+static int hf_lapdm_fragment = -1;
+static int hf_lapdm_fragment_overlap = -1;
+static int hf_lapdm_fragment_overlap_conflicts = -1;
+static int hf_lapdm_fragment_multiple_tails = -1;
+static int hf_lapdm_fragment_too_long_fragment = -1;
+static int hf_lapdm_fragment_error = -1;
+static int hf_lapdm_fragment_count = -1;
+static int hf_lapdm_reassembled_in = -1;
+static int hf_lapdm_reassembled_length = -1;
+
+static gint ett_lapdm = -1;
+static gint ett_lapdm_address = -1;
+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 reassembly_table lapdm_reassembly_table;
+
+static wmem_map_t *lapdm_last_n_s_map;
+
+static dissector_table_t lapdm_sapi_dissector_table;
+
+static gboolean reassemble_lapdm = TRUE;
+
+/*
+ * Bits in the address field.
+ */
+#define LAPDM_SAPI              0x1c    /* Service Access Point Identifier */
+#define LAPDM_SAPI_SHIFT        2
+#define LAPDM_CR                0x02    /* Command/Response bit */
+#define LAPDM_EA                0x01    /* First Address Extension bit */
+#define LAPDM_LPD               0x60    /* Link Protocol Discriminator */
+
+/*
+ * Bits in the length field.
+ */
+#define LAPDM_EL                0x01    /* Extended Length = 1 */
+#define LAPDM_M                 0x02    /* More fragments */
+#define LAPDM_M_SHIFT           1
+#define LAPDM_LEN               0xfc    /* Length */
+#define LAPDM_LEN_SHIFT         2
+
+#define LAPDM_HEADER_LEN 3
+#define LAPDM_HEADER_LEN_B4 2
+
+#define LAPDM_SAPI_RR_CC_MM     0
+#define LAPDM_SAPI_SMS          3
+
+/* Used only for U frames */
+static const xdlc_cf_items lapdm_cf_items = {
+    &hf_lapdm_n_r,
+    &hf_lapdm_n_s,
+    &hf_lapdm_p,
+    &hf_lapdm_f,
+    &hf_lapdm_s_ftype,
+    &hf_lapdm_u_modifier_cmd,
+    &hf_lapdm_u_modifier_resp,
+    &hf_lapdm_ftype_i,
+    &hf_lapdm_ftype_s_u
+};
+
+static const value_string lapdm_ea_vals[] = {
+    { 0,                "More octets" },
+    { 1,                "Final octet" },
+    { 0,                NULL }
+};
+
+static const value_string lapdm_sapi_vals[] = {
+    { LAPDM_SAPI_RR_CC_MM,      "RR/MM/CC" },
+    { LAPDM_SAPI_SMS,           "SMS/SS" },
+    { 0,                        NULL }
+};
+
+static const value_string lapdm_lpd_vals[] = {
+    { 0,                "Normal GSM" },
+    { 1,                "Cell broadcast service" },
+    { 0,                NULL }
+};
+
+static const value_string lapdm_m_vals[] = {
+    { 0,                "Last segment" },
+    { 1,                "More segments" },
+    { 0,                NULL }
+};
+
+static const value_string lapdm_el_vals[] = {
+    { 0,                "More octets" },
+    { 1,                "Final octet" },
+    { 0,                NULL }
+};
+
+
+static const fragment_items lapdm_frag_items = {
+    /* Fragment subtrees */
+    &ett_lapdm_fragment,
+    &ett_lapdm_fragments,
+    /* Fragment fields */
+    &hf_lapdm_fragments,
+    &hf_lapdm_fragment,
+    &hf_lapdm_fragment_overlap,
+    &hf_lapdm_fragment_overlap_conflicts,
+    &hf_lapdm_fragment_multiple_tails,
+    &hf_lapdm_fragment_too_long_fragment,
+    &hf_lapdm_fragment_error,
+    &hf_lapdm_fragment_count,
+    /* Reassembled in field */
+    &hf_lapdm_reassembled_in,
+    /* Reassembled length field */
+    &hf_lapdm_reassembled_length,
+    /* Reassembled data field */
+    NULL,
+    /* Tag */
+    "fragments"
+};
+
+static gboolean hdr_has_length(enum lapdm_hdr_type hdr_type)
+{
+    switch (hdr_type) {
+    case LAPDM_HDR_FMT_A:
+    case LAPDM_HDR_FMT_B:
+        return TRUE;
+    default:
+        return FALSE;
+    }
+}
+
+
+static int
+dissect_lapdm(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data)
+{
+    proto_tree *lapdm_tree, *addr_tree, *length_tree;
+    proto_item *lapdm_ti, *addr_ti, *length_ti;
+    guint8 addr, length, header_len, cr, sapi, len, n_s;
+    int control;
+    gboolean m;
+    tvbuff_t *payload;
+    int available_length;
+    gboolean is_response = FALSE;
+    enum lapdm_hdr_type hdr_type = LAPDM_HDR_FMT_B;
+    gboolean is_acch = FALSE, is_ui_frame = FALSE;
+
+    if (data) {
+        lapdm_data_t *ld = (lapdm_data_t *) data;
+        is_acch = ld->is_acch;
+    }
+
+    /* Check that there's enough data */
+    if (tvb_captured_length(tvb) < LAPDM_HEADER_LEN_B4)
+        return 0;
+
+    control = tvb_get_guint8(tvb, 1);
+    is_ui_frame = (control & XDLC_S_U_MASK) == XDLC_U && (control & XDLC_U_MODIFIER_MASK) == XDLC_UI;
+
+    /* only downlink UI SACCH frames use B4 header format */
+    if (is_acch && is_ui_frame && pinfo->p2p_dir == P2P_DIR_RECV) {
+        hdr_type = LAPDM_HDR_FMT_B4;
+        header_len = LAPDM_HEADER_LEN_B4;
+        length = 0;
+    } else {
+        header_len = LAPDM_HEADER_LEN;
+
+        /* Check that there's enough data */
+        if (tvb_captured_length(tvb) < header_len)
+            return 0;
+
+        length = tvb_get_guint8(tvb, 2);
+    }
+
+    col_set_str(pinfo->cinfo, COL_PROTOCOL, "LAPDm");
+
+    addr = tvb_get_guint8(tvb, 0);
+
+    cr = addr & LAPDM_CR;
+    if (pinfo->p2p_dir == P2P_DIR_RECV) {
+        is_response = cr ? FALSE : TRUE;
+    }
+    else if (pinfo->p2p_dir == P2P_DIR_SENT) {
+        is_response = cr ? TRUE : FALSE;
+    }
+
+    if (tree) {
+        lapdm_ti = proto_tree_add_item(tree, proto_lapdm, tvb, 0, header_len, ENC_NA);
+        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_sapi, tvb, 0, 1, addr);
+        proto_tree_add_uint(addr_tree, hf_lapdm_cr, tvb, 0, 1, addr);
+        proto_tree_add_uint(addr_tree, hf_lapdm_ea, tvb, 0, 1, addr);
+    }
+    else {
+        lapdm_ti = NULL;
+        lapdm_tree = NULL;
+    }
+
+    control = dissect_xdlc_control(tvb, 1, pinfo, lapdm_tree, hf_lapdm_control,
+                                   ett_lapdm_control, &lapdm_cf_items, NULL /* LAPDm doesn't support extended */, NULL, NULL,
+                                   is_response, FALSE, FALSE);
+
+    /* dissect length field (if present) */
+    if (tree && hdr_has_length(hdr_type)) {
+        length_ti = proto_tree_add_uint(lapdm_tree, hf_lapdm_length, tvb,
+                                        2, 1, length);
+        length_tree = proto_item_add_subtree(length_ti, ett_lapdm_length);
+
+        proto_tree_add_uint(length_tree, hf_lapdm_len, tvb, 2, 1, length);
+        proto_tree_add_uint(length_tree, hf_lapdm_m, tvb, 2, 1, length);
+        proto_tree_add_uint(length_tree, hf_lapdm_el, tvb, 2, 1, length);
+    }
+
+    if (hdr_has_length(hdr_type)) {
+        len = (length & LAPDM_LEN) >> LAPDM_LEN_SHIFT;
+        m = (length & LAPDM_M) >> LAPDM_M_SHIFT;
+    } else {
+        len = tvb_captured_length(tvb) - header_len;
+        m = 0;
+    }
+
+    sapi = (addr & LAPDM_SAPI) >> LAPDM_SAPI_SHIFT;
+    n_s = (control & XDLC_N_S_MASK) >> XDLC_N_S_SHIFT;
+    available_length = tvb_captured_length(tvb) - header_len;
+
+    /* No point in doing anything if no payload
+     */
+    if( !MIN(len, available_length) )
+        return 2;
+
+    payload = tvb_new_subset_length_caplen(tvb, header_len, MIN(len,available_length), len);
+
+    /* Potentially segmented I frame
+     */
+    if( (control & XDLC_I_MASK) == XDLC_I && reassemble_lapdm && !pinfo->flags.in_error_pkt )
+    {
+        fragment_head *fd_m = NULL;
+        tvbuff_t *reassembled = NULL;
+        guint32 fragment_id;
+        gboolean save_fragmented = pinfo->fragmented, add_frag;
+
+        pinfo->fragmented = m;
+
+        /* Rely on caller to provide a way to group fragments */
+        fragment_id =  (conversation_get_id_from_elements(pinfo, CONVERSATION_GSMTAP, USE_LAST_ENDPOINT) << 4) | (sapi << 1) | pinfo->p2p_dir;
+
+        if (!PINFO_FD_VISITED(pinfo)) {
+            /* Check if new N(S) is equal to previous N(S) (to avoid adding retransmissions in reassembly table)
+               As GUINT_TO_POINTER macro does not allow to differentiate NULL from 0, use 1-8 range instead of 0-7 */
+            guint *p_last_n_s = (guint*)wmem_map_lookup(lapdm_last_n_s_map, GUINT_TO_POINTER(fragment_id));
+            if (GPOINTER_TO_UINT(p_last_n_s) == (guint)(n_s+1)) {
+                add_frag = FALSE;
+            } else {
+                add_frag = TRUE;
+                wmem_map_insert(lapdm_last_n_s_map, GUINT_TO_POINTER(fragment_id), GUINT_TO_POINTER(n_s+1));
+            }
+        } else {
+            add_frag = TRUE;
+        }
+
+        if (add_frag) {
+            /* This doesn't seem the best way of doing it as doesn't
+            take N(S) into account, but N(S) isn't always 0 for
+            the first fragment!
+            */
+            fd_m = fragment_add_seq_next (&lapdm_reassembly_table, payload, 0,
+                                        pinfo,
+                                        fragment_id, /* guint32 ID for fragments belonging together */
+                                        NULL,
+                                        /*n_s guint32 fragment sequence number */
+                                        len, /* guint32 fragment length */
+                                        m); /* More fragments? */
+
+            reassembled = process_reassembled_data(payload, 0, pinfo,
+                                                "Reassembled LAPDm", fd_m, &lapdm_frag_items,
+                                                NULL, lapdm_tree);
+
+            /* Reassembled into this packet
+            */
+            if (fd_m && pinfo->num == fd_m->reassembled_in) {
+                if (!dissector_try_uint(lapdm_sapi_dissector_table, sapi,
+                                        reassembled, pinfo, tree))
+                    call_data_dissector(reassembled, pinfo, tree);
+
+                if (!PINFO_FD_VISITED(pinfo)) {
+                    /* If reassembling is done, allow fragment_id reuse */
+                    wmem_map_remove(lapdm_last_n_s_map, GUINT_TO_POINTER(fragment_id));
+                }
+            }
+            else {
+                col_append_str(pinfo->cinfo, COL_INFO, " (Fragment)");
+                proto_tree_add_item(lapdm_tree, hf_lapdm_fragment_data, payload, 0, -1, ENC_NA);
+            }
+        }
+
+        /* Now reset fragmentation information in pinfo
+         */
+        pinfo->fragmented = save_fragmented;
+    }
+    else if (hdr_type == LAPDM_HDR_FMT_B4)
+    {
+        /* B4 frames have no length octet at L2 level, but instead a L2 pseudo length octet
+         * at L3.  We must call the proper dissector for decoding them */
+        call_dissector(b4_info_handle, payload, pinfo, tree);
+    }
+    else
+    {
+        if (!PINFO_FD_VISITED(pinfo) && ((control & XDLC_S_U_MASK) == XDLC_U) && ((control & XDLC_U_MODIFIER_MASK) == XDLC_SABM)) {
+            /* SABM frame; reset the last N(S) to an invalid value */
+            guint32 fragment_id = (conversation_get_id_from_elements(pinfo, CONVERSATION_GSMTAP, USE_LAST_ENDPOINT) << 4) | (sapi << 1) | pinfo->p2p_dir;
+            wmem_map_insert(lapdm_last_n_s_map, GUINT_TO_POINTER(fragment_id), GUINT_TO_POINTER(0));
+        }
+
+        /* Whole packet
+           If we have some data, try and dissect it (only happens for UI, SABM, UA or I frames)
+        */
+        if (!dissector_try_uint(lapdm_sapi_dissector_table, sapi,
+                                payload, pinfo, tree))
+            call_data_dissector(payload, pinfo, tree);
+    }
+    return tvb_captured_length(tvb);
+}
+
+void
+proto_register_lapdm(void)
+{
+    static hf_register_info hf[] = {
+
+        { &hf_lapdm_address,
+          { "Address Field", "lapdm.address_field", FT_UINT8, BASE_HEX, NULL, 0x0,
+            "Address", HFILL }},
+
+        { &hf_lapdm_ea,
+          { "EA", "lapdm.ea", FT_UINT8, BASE_DEC, VALS(lapdm_ea_vals), LAPDM_EA,
+            "Address field extension bit", HFILL }},
+
+        { &hf_lapdm_cr,
+          { "C/R", "lapdm.cr", FT_UINT8, BASE_DEC, NULL, LAPDM_CR,
+            "Command/response field bit", HFILL }},
+
+        { &hf_lapdm_lpd,
+          { "LPD", "lapdm.lpd", FT_UINT8, BASE_DEC, VALS(lapdm_lpd_vals), LAPDM_LPD,
+            "Link Protocol Discriminator", HFILL }},
+
+        { &hf_lapdm_sapi,
+          { "SAPI", "lapdm.sapi", FT_UINT8, BASE_DEC, VALS(lapdm_sapi_vals), LAPDM_SAPI,
+            "Service access point identifier", HFILL }},
+
+        { &hf_lapdm_control,
+          { "Control Field", "lapdm.control_field", FT_UINT8, BASE_HEX, NULL, 0x0,
+            NULL, HFILL }},
+
+        { &hf_lapdm_n_r,
+          { "N(R)", "lapdm.control.n_r", FT_UINT8, BASE_DEC,
+            NULL, XDLC_N_R_MASK, NULL, HFILL }},
+
+        { &hf_lapdm_n_s,
+          { "N(S)", "lapdm.control.n_s", FT_UINT8, BASE_DEC,
+            NULL, XDLC_N_S_MASK, NULL, HFILL }},
+
+        { &hf_lapdm_p,
+          { "Poll", "lapdm.control.p", FT_BOOLEAN, 8,
+            NULL, XDLC_P_F, NULL, HFILL }},
+
+        { &hf_lapdm_f,
+          { "Final", "lapdm.control.f", FT_BOOLEAN, 8,
+            NULL, XDLC_P_F, NULL, HFILL }},
+
+        { &hf_lapdm_s_ftype,
+          { "Supervisory frame type", "lapdm.control.s_ftype", FT_UINT8, BASE_HEX,
+            VALS(stype_vals), XDLC_S_FTYPE_MASK, NULL, HFILL }},
+
+        { &hf_lapdm_u_modifier_cmd,
+          { "Command", "lapdm.control.u_modifier_cmd", FT_UINT8, BASE_HEX,
+            VALS(modifier_vals_cmd), XDLC_U_MODIFIER_MASK, NULL, HFILL }},
+
+        { &hf_lapdm_u_modifier_resp,
+          { "Response", "lapdm.control.u_modifier_resp", FT_UINT8, BASE_HEX,
+            VALS(modifier_vals_resp), XDLC_U_MODIFIER_MASK, NULL, HFILL }},
+
+        { &hf_lapdm_ftype_i,
+          { "Frame type", "lapdm.control.ftype", FT_UINT8, BASE_HEX,
+            VALS(ftype_vals), XDLC_I_MASK, NULL, HFILL }},
+
+        { &hf_lapdm_ftype_s_u,
+          { "Frame type", "lapdm.control.ftype", FT_UINT8, BASE_HEX,
+            VALS(ftype_vals), XDLC_S_U_MASK, NULL, HFILL }},
+
+        { &hf_lapdm_length,
+          { "Length Field", "lapdm.length_field", FT_UINT8, BASE_HEX,
+            NULL, 0x0, NULL, HFILL }},
+
+        { &hf_lapdm_el,
+          { "EL", "lapdm.el", FT_UINT8, BASE_DEC,
+            VALS(lapdm_el_vals), LAPDM_EL, "Length indicator field extension bit", HFILL }},
+
+        { &hf_lapdm_m,
+          { "M", "lapdm.m", FT_UINT8, BASE_DEC,
+            VALS(lapdm_m_vals), LAPDM_M, "More data bit", HFILL }},
+
+        { &hf_lapdm_len,
+          { "Length", "lapdm.length", FT_UINT8, BASE_DEC,
+            NULL, LAPDM_LEN, "Length indicator", HFILL }},
+
+        /* Fragment reassembly
+         */
+        { &hf_lapdm_fragment_data,
+          { "Fragment Data", "lapdm.fragment_data", FT_NONE, BASE_NONE,
+            NULL, 0x00, NULL, HFILL }},
+
+        { &hf_lapdm_fragments,
+          { "Message fragments", "lapdm.fragments", FT_NONE, BASE_NONE,
+            NULL, 0x00, "LAPDm Message fragments", HFILL }},
+
+        { &hf_lapdm_fragment,
+          { "Message fragment", "lapdm.fragment", FT_FRAMENUM, BASE_NONE,
+            NULL, 0x00, "LAPDm Message fragment", HFILL }},
+
+        { &hf_lapdm_fragment_overlap,
+          { "Message fragment overlap", "lapdm.fragment.overlap", FT_BOOLEAN, BASE_NONE,
+            NULL, 0x0, "LAPDm Message fragment overlaps with other fragment(s)", HFILL }},
+
+        { &hf_lapdm_fragment_overlap_conflicts,
+          { "Message fragment overlapping with conflicting data", "lapdm.fragment.overlap.conflicts", FT_BOOLEAN, BASE_NONE,
+            NULL, 0x0, "LAPDm Message fragment overlaps with conflicting data", HFILL }},
+
+        { &hf_lapdm_fragment_multiple_tails,
+          { "Message has multiple tail fragments", "lapdm.fragment.multiple_tails", FT_BOOLEAN, BASE_NONE,
+            NULL, 0x0, "LAPDm Message fragment has multiple tail fragments", HFILL }},
+
+        { &hf_lapdm_fragment_too_long_fragment,
+          { "Message fragment too long", "lapdm.fragment.too_long_fragment", FT_BOOLEAN, BASE_NONE,
+            NULL, 0x0, "LAPDm Message fragment data goes beyond the packet end", HFILL }},
+
+        { &hf_lapdm_fragment_error,
+          { "Message defragmentation error", "lapdm.fragment.error", FT_FRAMENUM, BASE_NONE,
+            NULL, 0x00, "LAPDm Message defragmentation error due to illegal fragments", HFILL }},
+
+        { &hf_lapdm_fragment_count,
+          { "Message fragment count", "lapdm.fragment.count", FT_UINT32, BASE_DEC,
+            NULL, 0x00, NULL, HFILL }},
+
+        { &hf_lapdm_reassembled_in,
+          { "Reassembled in", "lapdm.reassembled.in", FT_FRAMENUM, BASE_NONE,
+            NULL, 0x00, "LAPDm Message has been reassembled in this packet.", HFILL }},
+
+        { &hf_lapdm_reassembled_length,
+          { "Reassembled LAPDm length", "lapdm.reassembled.length", FT_UINT32, BASE_DEC,
+            NULL, 0x00, "The total length of the reassembled payload", HFILL }}
+
+    };
+    static gint *ett[] = {
+        &ett_lapdm,
+        &ett_lapdm_address,
+        &ett_lapdm_control,
+        &ett_lapdm_length,
+        &ett_lapdm_fragment,
+        &ett_lapdm_fragments
+    };
+
+    module_t *lapdm_module;
+
+    proto_lapdm = proto_register_protocol("Link Access Procedure, Channel Dm (LAPDm)", "LAPDm", "lapdm");
+    proto_register_field_array (proto_lapdm, hf, array_length(hf));
+    proto_register_subtree_array(ett, array_length(ett));
+
+    register_dissector("lapdm", dissect_lapdm, proto_lapdm);
+
+    lapdm_sapi_dissector_table = register_dissector_table("lapdm.sapi", "LAPDm SAPI", proto_lapdm, FT_UINT8, BASE_DEC);
+
+    lapdm_module = prefs_register_protocol(proto_lapdm, NULL);
+    prefs_register_bool_preference(lapdm_module, "reassemble",
+                                   "Reassemble fragmented LAPDm packets",
+                                   "Whether the dissector should defragment LAPDm messages spanning multiple packets.",
+                                   &reassemble_lapdm);
+
+    lapdm_last_n_s_map = wmem_map_new_autoreset(wmem_epan_scope(), wmem_file_scope(), g_direct_hash, g_direct_equal);
+
+    reassembly_table_register(&lapdm_reassembly_table,
+                           &addresses_reassembly_table_functions);
+
+    /* B4 frames have no length octet at L2 level, but instead a L2 pseudo length octet
+     * at L3.  We must call the proper dissector for decoding them, and gsm_a_ccch supports
+     * L2 pseudo length */
+    b4_info_handle = find_dissector_add_dependency("gsm_a_ccch", proto_lapdm);
+}
+
+/*
+ * Editor modelines  -  https://www.wireshark.org/tools/modelines.html
+ *
+ * Local variables:
+ * c-basic-offset: 4
+ * tab-width: 8
+ * indent-tabs-mode: nil
+ * End:
+ *
+ * vi: set shiftwidth=4 tabstop=8 expandtab:
+ * :indentSize=4:tabSize=8:noTabs=true:
+ */