forked from osmocom/wireshark
DECT-DLC: Reassemble fragments
The DECT-DLC dissector now reassembles fragments before handing them over to the NWK layer. Most of this is done by reusing of the reassembly code from packet-lapdm.c.
This commit is contained in:
Bernhard Dick
AndersBroman
parent
594207d04e
commit
9a96284e5a
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@ -16,8 +16,10 @@
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*/
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#include "config.h"
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#include <epan/conversation.h>
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#include <epan/packet.h>
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#include <epan/prefs.h>
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#include <epan/reassemble.h>
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#include <epan/xdlc.h>
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static int proto_dect_dlc = -1;
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@ -53,6 +55,52 @@ static dissector_handle_t data_handle;
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static dissector_table_t dlc_sapi_dissector_table;
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static reassembly_table dect_dlc_reassembly_table;
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static int hf_dect_dlc_fragment_data = -1;
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static int hf_dect_dlc_fragment = -1;
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static int hf_dect_dlc_fragments = -1;
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static int hf_dect_dlc_fragment_overlap = -1;
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static int hf_dect_dlc_fragment_overlap_conflicts = -1;
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static int hf_dect_dlc_fragment_multiple_tails = -1;
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static int hf_dect_dlc_fragment_too_long_fragment = -1;
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static int hf_dect_dlc_fragment_error = -1;
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static int hf_dect_dlc_fragment_count = -1;
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static int hf_dect_dlc_reassembled_in = -1;
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static int hf_dect_dlc_reassembled_length = -1;
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static gint ett_dect_dlc_fragment = -1;
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static gint ett_dect_dlc_fragments = -1;
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static const fragment_items dlc_frag_items = {
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/* Fragment subtrees */
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&ett_dect_dlc_fragment,
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&ett_dect_dlc_fragments,
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/* Fragment fields */
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&hf_dect_dlc_fragments,
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&hf_dect_dlc_fragment,
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&hf_dect_dlc_fragment_overlap,
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&hf_dect_dlc_fragment_overlap_conflicts,
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&hf_dect_dlc_fragment_multiple_tails,
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&hf_dect_dlc_fragment_too_long_fragment,
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&hf_dect_dlc_fragment_error,
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&hf_dect_dlc_fragment_count,
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/* Reassembled in field */
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&hf_dect_dlc_reassembled_in,
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/* Reassembled length field */
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&hf_dect_dlc_reassembled_length,
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/* Reassembled data field */
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NULL,
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/* Tag */
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"fragments"
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};
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static wmem_map_t *dect_dlc_last_n_s_map;
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#define DECT_DLC_M 0x02
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#define DECT_DLC_M_SHIFT 1
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static gboolean reassemble_dect_dlc = TRUE;
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static const xdlc_cf_items dlc_cf_items = {
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&hf_dlc_n_r,
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@ -102,9 +150,11 @@ static int dissect_dect_dlc(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree,
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proto_tree *dlc_tree, *addr_tree, *length_tree;
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proto_item *dlc_ti, *addr_ti, *length_ti;
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gboolean is_response = FALSE;
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gboolean m;
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int available_length;
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int control;
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tvbuff_t *payload;
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guint8 cr, sapi, length, len;
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guint8 cr, sapi, length, len, n_s;
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col_set_str(pinfo->cinfo, COL_PROTOCOL, "DECT-DLC");
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@ -126,9 +176,10 @@ static int dissect_dect_dlc(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree,
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proto_tree_add_item(addr_tree, hf_dlc_sapi, tvb, 0, 1, ENC_NA);
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proto_tree_add_item(addr_tree, hf_dlc_cr, tvb, 0, 1, ENC_NA);
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dissect_xdlc_control(tvb, 1, pinfo, dlc_tree, hf_dlc_control,
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control = dissect_xdlc_control(tvb, 1, pinfo, dlc_tree, hf_dlc_control,
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ett_dect_dlc_control, &dlc_cf_items, NULL, NULL, NULL,
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is_response, FALSE, FALSE);
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n_s = (control & XDLC_N_S_MASK) >> XDLC_N_S_SHIFT;
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length_ti = proto_tree_add_item(dlc_tree, hf_dlc_length, tvb, 2, 1, ENC_NA);
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length_tree = proto_item_add_subtree(length_ti, ett_dect_dlc_length);
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@ -142,10 +193,74 @@ static int dissect_dect_dlc(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree,
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if (available_length > 0) {
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payload = tvb_new_subset_length_caplen(tvb, 3, MIN(len, available_length), len);
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/* FIXME: fragment reassembly like in packet-lapdm.c */
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/* Potentially segmented I frame */
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if( (control & XDLC_I_MASK) == XDLC_I && reassemble_dect_dlc && !pinfo->flags.in_error_pkt )
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{
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fragment_head *fd_m = NULL;
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tvbuff_t *reassembled = NULL;
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guint32 fragment_id;
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gboolean save_fragmented = pinfo->fragmented, add_frag;
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if (!dissector_try_uint(dlc_sapi_dissector_table, sapi, payload, pinfo, tree))
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call_data_dissector(payload, pinfo, tree);
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m = (length & DECT_DLC_M) >> DECT_DLC_M_SHIFT;
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pinfo->fragmented = m;
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fragment_id = (conversation_get_id_from_elements(pinfo, CONVERSATION_NONE, USE_LAST_ENDPOINT) << 3) | ( sapi << 1) | pinfo->p2p_dir;
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if (!PINFO_FD_VISITED(pinfo)) {
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/* Check if new N(S) is equal to previous N(S) (to avoid adding retransmissions in reassembly table)
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As GUINT_TO_POINTER macro does not allow to differentiate NULL from 0, use 1-8 range instead of 0-7 */
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guint *p_last_n_s = (guint*)wmem_map_lookup(dect_dlc_last_n_s_map, GUINT_TO_POINTER(fragment_id));
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if (GPOINTER_TO_UINT(p_last_n_s) == (guint)(n_s+1)) {
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add_frag = FALSE;
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} else {
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add_frag = TRUE;
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wmem_map_insert(dect_dlc_last_n_s_map, GUINT_TO_POINTER(fragment_id), GUINT_TO_POINTER(n_s+1));
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}
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} else {
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add_frag = TRUE;
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}
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if (add_frag) {
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/* This doesn't seem the best way of doing it as doesn't
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take N(S) into account, but N(S) isn't always 0 for
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the first fragment! */
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fd_m = fragment_add_seq_next (&dect_dlc_reassembly_table, payload, 0,
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pinfo,
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fragment_id, /* guint32 ID for fragments belonging together */
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NULL,
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/*n_s guint32 fragment sequence number */
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len, /* guint32 fragment length */
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m); /* More fragments? */
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reassembled = process_reassembled_data(payload, 0, pinfo,
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"Reassembled DLC", fd_m, &dlc_frag_items,
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NULL, dlc_tree);
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/* Reassembled into this packet */
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if (fd_m && pinfo->num == fd_m->reassembled_in) {
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if (!dissector_try_uint(dlc_sapi_dissector_table, sapi,
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reassembled, pinfo, tree))
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call_data_dissector(reassembled, pinfo, tree);
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}
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else {
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col_append_str(pinfo->cinfo, COL_INFO, " (Fragment)");
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proto_tree_add_item(dlc_tree, hf_dect_dlc_fragment_data, payload, 0, -1, ENC_NA);
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}
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}
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/* Now reset fragmentation information in pinfo */
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pinfo->fragmented = save_fragmented;
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}
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else
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{
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if (!PINFO_FD_VISITED(pinfo) && ((control & XDLC_S_U_MASK) == XDLC_U) && ((control & XDLC_U_MODIFIER_MASK) == XDLC_SABM)) {
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/* SABM frame; reset the last N(S) to an invalid value */
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guint32 fragment_id = (conversation_get_id_from_elements(pinfo, CONVERSATION_GSMTAP, USE_LAST_ENDPOINT) << 3) | (sapi << 1) | pinfo->p2p_dir;
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wmem_map_insert(dect_dlc_last_n_s_map, GUINT_TO_POINTER(fragment_id), GUINT_TO_POINTER(0));
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}
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if (!dissector_try_uint(dlc_sapi_dissector_table, sapi, payload, pinfo, tree))
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call_data_dissector(payload, pinfo, tree);
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}
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}
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return tvb_captured_length(tvb);
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@ -251,6 +366,64 @@ void proto_register_dect_dlc(void)
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}
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},
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/* Fragment reassembly */
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{ &hf_dect_dlc_fragment_data,
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{ "Fragment Data", "dect_dlc.fragment_data", FT_NONE, BASE_NONE,
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NULL, 0x00, NULL, HFILL
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}
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},
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{ &hf_dect_dlc_fragments,
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{ "Message fragments", "dect_dlc.fragments",
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FT_NONE, BASE_NONE, NULL, 0x00, NULL, HFILL
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}
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},
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{ &hf_dect_dlc_fragment,
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{ "Message fragment", "dlc_.fragment",
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FT_FRAMENUM, BASE_NONE, NULL, 0x00, NULL, HFILL
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}
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},
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{ &hf_dect_dlc_fragment_overlap,
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{ "Message fragment overlap", "dect_dlc.fragment.overlap",
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FT_BOOLEAN, 0, NULL, 0x00, NULL, HFILL
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}
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},
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{ &hf_dect_dlc_fragment_overlap_conflicts,
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{ "Message fragment overlapping with conflicting data",
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"dect_dlc.fragment.overlap.conflicts",
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FT_BOOLEAN, 0, NULL, 0x00, NULL, HFILL
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}
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},
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{ &hf_dect_dlc_fragment_multiple_tails,
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{ "Message has multiple tail fragments",
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"dect_dlc.fragment.multiple_tails",
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FT_BOOLEAN, 0, NULL, 0x00, NULL, HFILL
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}
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},
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{ &hf_dect_dlc_fragment_too_long_fragment,
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{ "Message fragment too long", "dect_dlc.fragment.too_long_fragment",
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FT_BOOLEAN, 0, NULL, 0x00, NULL, HFILL
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}
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},
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{ &hf_dect_dlc_fragment_error,
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{ "Message defragmentation error", "dect_dlc.fragment.error",
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FT_FRAMENUM, BASE_NONE, NULL, 0x00, NULL, HFILL
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}
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},
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{ &hf_dect_dlc_fragment_count,
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{ "Message fragment count", "dect_dlc.fragment.count",
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FT_UINT32, BASE_DEC, NULL, 0x00, NULL, HFILL
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}
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},
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{ &hf_dect_dlc_reassembled_in,
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{ "Reassembled in", "dect_dlc.reassembled.in",
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FT_FRAMENUM, BASE_NONE, NULL, 0x00, NULL, HFILL
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}
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},
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{ &hf_dect_dlc_reassembled_length,
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{ "Reassembled length", "dect_dlc.reassembled.length",
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FT_UINT32, BASE_DEC, NULL, 0x00, NULL, HFILL
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}
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},
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};
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static gint *ett[] = {
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@ -258,6 +431,8 @@ void proto_register_dect_dlc(void)
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&ett_dect_dlc_address,
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&ett_dect_dlc_control,
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&ett_dect_dlc_length,
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&ett_dect_dlc_fragment,
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&ett_dect_dlc_fragments,
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};
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/* Register protocol */
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@ -271,6 +446,10 @@ void proto_register_dect_dlc(void)
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dlc_sapi_dissector_table = register_dissector_table("dect_dlc.sapi", "DECT DLC SAPI", proto_dect_dlc, FT_UINT8, BASE_DEC);
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data_handle = find_dissector("data");
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reassembly_table_register(&dect_dlc_reassembly_table,
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&addresses_reassembly_table_functions);
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dect_dlc_last_n_s_map = wmem_map_new_autoreset(wmem_epan_scope(), wmem_file_scope(), g_direct_hash, g_direct_equal);
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}
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#if 0
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