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DVB-S2: Reassemble GSE frames. 

Large data (for example big DVB-RCS2 tables) can be fragmented at the
GSE level. Reassembly is required to properly decode the data.

Change-Id: I555148e99d43e610208bd87fc64a4bc212fea4b2
Reviewed-on: https://code.wireshark.org/review/37592
Petri-Dish: Anders Broman <a.broman58@gmail.com>
Tested-by: Petri Dish Buildbot
Reviewed-by: Anders Broman <a.broman58@gmail.com>
This commit is contained in:
Adrien Destugues 2018-05-17 10:41:07 +02:00 committed by Anders Broman
parent fb215255bb
commit 73d1721db6
1 changed files with 128 additions and 5 deletions
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133
epan/dissectors/packet-dvb-s2-bb.c
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@ -27,6 +27,7 @@
#include <epan/prefs.h>
#include <epan/etypes.h>
#include <epan/expert.h>
#include <epan/reassemble.h>
#define BIT_IS_SET(var, bit) ((var) & (1 << (bit)))
#define BIT_IS_CLEAR(var, bit) !BIT_IS_SET(var, bit)
@ -150,6 +151,49 @@ static expert_field ei_dvb_s2_bb_npd_invalid = EI_INIT;
static expert_field ei_dvb_s2_bb_upl_invalid = EI_INIT;
static expert_field ei_dvb_s2_bb_reserved = EI_INIT;
/* Reassembly support */
static reassembly_table dvbs2_reassembly_table;
static void
dvbs2_defragment_init(void)
{
reassembly_table_init(&dvbs2_reassembly_table,
&addresses_reassembly_table_functions);
}
static gint ett_dvbs2_fragments = -1;
static gint ett_dvbs2_fragment = -1;
static int hf_dvbs2_fragments = -1;
static int hf_dvbs2_fragment = -1;
static int hf_dvbs2_fragment_overlap = -1;
static int hf_dvbs2_fragment_overlap_conflict = -1;
static int hf_dvbs2_fragment_multiple_tails = -1;
static int hf_dvbs2_fragment_too_long_fragment = -1;
static int hf_dvbs2_fragment_error = -1;
static int hf_dvbs2_fragment_count = -1;
static int hf_dvbs2_reassembled_in = -1;
static int hf_dvbs2_reassembled_length = -1;
static int hf_dvbs2_reassembled_data = -1;
static const fragment_items dvbs2_frag_items = {
&ett_dvbs2_fragment,
&ett_dvbs2_fragments,
&hf_dvbs2_fragments,
&hf_dvbs2_fragment,
&hf_dvbs2_fragment_overlap,
&hf_dvbs2_fragment_overlap_conflict,
&hf_dvbs2_fragment_multiple_tails,
&hf_dvbs2_fragment_too_long_fragment,
&hf_dvbs2_fragment_error,
&hf_dvbs2_fragment_count,
&hf_dvbs2_reassembled_in,
&hf_dvbs2_reassembled_length,
&hf_dvbs2_reassembled_data,
"DVB-S2 fragments"
};
static unsigned char _use_low_rolloff_value = 0;
/* Offset in SYNC MARKER */
@ -848,6 +892,7 @@ static int dissect_dvb_s2_gse(tvbuff_t *tvb, int cur_off, proto_tree *tree, pack
tvbuff_t *next_tvb, *data_tvb;
gboolean dissected = FALSE;
gboolean update_col_info = TRUE;
static int * const gse_header_bitfields[] = {
&hf_dvb_s2_gse_hdr_start,
@ -884,20 +929,23 @@ static int dissect_dvb_s2_gse(tvbuff_t *tvb, int cur_off, proto_tree *tree, pack
proto_tree_add_bitmask_with_flags(dvb_s2_gse_tree, tvb, cur_off + DVB_S2_GSE_OFFS_HDR, hf_dvb_s2_gse_hdr,
ett_dvb_s2_gse_hdr, gse_header_bitfields, ENC_BIG_ENDIAN, BMT_NO_TFS);
/* Get the fragment ID for reassembly */
guint8 fragid = tvb_get_guint8(tvb, cur_off + new_off);
if (BIT_IS_CLEAR(gse_hdr, DVB_S2_GSE_HDR_START_POS) || BIT_IS_CLEAR(gse_hdr, DVB_S2_GSE_HDR_STOP_POS)) {
/* Not a start or end packet, add only the fragid */
proto_tree_add_item(dvb_s2_gse_tree, hf_dvb_s2_gse_fragid, tvb, cur_off + new_off, 1, ENC_BIG_ENDIAN);
new_off += 1;
}
if (BIT_IS_SET(gse_hdr, DVB_S2_GSE_HDR_START_POS) && BIT_IS_CLEAR(gse_hdr, DVB_S2_GSE_HDR_STOP_POS)) {
/* Start packet, add the fragment size */
proto_tree_add_item(dvb_s2_gse_tree, hf_dvb_s2_gse_totlength, tvb, cur_off + new_off, 2, ENC_BIG_ENDIAN);
col_append_str(pinfo->cinfo, COL_INFO, "(frag) ");
new_off += 2;
}
if (BIT_IS_SET(gse_hdr, DVB_S2_GSE_HDR_START_POS)) {
/* Start packet, decode the header */
gse_proto = tvb_get_ntohs(tvb, cur_off + new_off);
proto_tree_add_item(dvb_s2_gse_tree, hf_dvb_s2_gse_proto, tvb, cur_off + new_off, 2, ENC_BIG_ENDIAN);
@ -950,7 +998,32 @@ static int dissect_dvb_s2_gse(tvbuff_t *tvb, int cur_off, proto_tree *tree, pack
data_len = (gse_hdr & DVB_S2_GSE_HDR_LENGTH_MASK) - (new_off - DVB_S2_GSE_MINSIZE);
}
data_tvb = tvb_new_subset_length(tvb, cur_off + new_off, data_len);
data_tvb = NULL;
if (BIT_IS_CLEAR(gse_hdr, DVB_S2_GSE_HDR_START_POS) || BIT_IS_CLEAR(gse_hdr, DVB_S2_GSE_HDR_STOP_POS)) {
fragment_head *dvbs2_frag_head = NULL;
int offset = cur_off + new_off;
if (BIT_IS_SET(gse_hdr, DVB_S2_GSE_HDR_START_POS)) {
offset -= 2; /* re-include GSE type in reassembled data */
data_len += 2;
}
dvbs2_frag_head = fragment_add_seq_next(&dvbs2_reassembly_table, tvb, offset,
pinfo, fragid, NULL, data_len, BIT_IS_CLEAR(gse_hdr, DVB_S2_GSE_HDR_STOP_POS));
if (BIT_IS_SET(gse_hdr, DVB_S2_GSE_HDR_STOP_POS))
dvbs2_frag_head = fragment_end_seq_next(&dvbs2_reassembly_table, pinfo, fragid, NULL);
data_tvb = process_reassembled_data(tvb, cur_off + new_off, pinfo, "Reassembled DVB-S2",
dvbs2_frag_head, &dvbs2_frag_items, &update_col_info, tree);
}
if (data_tvb != NULL) {
/* We have a reassembled packet. Extract the gse_proto from it. */
gse_proto = tvb_get_ntohs(data_tvb, 0);
/* And then remove it from the reassembled data */
data_tvb = tvb_new_subset_remaining(data_tvb, 2);
} else {
data_tvb = tvb_new_subset_length(tvb, cur_off + new_off, data_len);
}
switch (gse_proto) {
case ETHERTYPE_IP:
@ -1534,13 +1607,61 @@ void proto_register_dvb_s2_modeadapt(void)
"CRC", "dvb-s2_gse.crc",
FT_UINT32, BASE_HEX, NULL, 0x0,
"CRC-32", HFILL}
}
},
{ &hf_dvbs2_fragment_overlap,
{ "Fragment overlap", "dvb-s2_gse.fragment.overlap", FT_BOOLEAN, BASE_NONE,
NULL, 0x0, "Fragment overlaps with other fragments", HFILL }},
{ &hf_dvbs2_fragment_overlap_conflict,
{ "Conflicting data in fragment overlap", "dvb-s2_gse.fragment.overlap.conflict",
FT_BOOLEAN, BASE_NONE, NULL, 0x0,
"Overlapping fragments contained conflicting data", HFILL }},
{ &hf_dvbs2_fragment_multiple_tails,
{ "Multiple tail fragments found", "dvb-s2_gse.fragment.multipletails",
FT_BOOLEAN, BASE_NONE, NULL, 0x0,
"Several tails were found when defragmenting the packet", HFILL }},
{ &hf_dvbs2_fragment_too_long_fragment,
{ "Fragment too long", "dvb-s2_gse.fragment.toolongfragment",
FT_BOOLEAN, BASE_NONE, NULL, 0x0,
"Fragment contained data past end of packet", HFILL }},
{ &hf_dvbs2_fragment_error,
{ "Defragmentation error", "dvb-s2_gse.fragment.error", FT_FRAMENUM, BASE_NONE,
NULL, 0x0, "Defragmentation error due to illegal fragments", HFILL }},
{ &hf_dvbs2_fragment_count,
{ "Fragment count", "dvb-s2_gse.fragment.count", FT_UINT32, BASE_DEC,
NULL, 0x0, NULL, HFILL }},
{ &hf_dvbs2_fragment,
{ "DVB-S2 GSE Fragment", "dvb-s2_gse.fragment", FT_FRAMENUM, BASE_NONE,
NULL, 0x0, NULL, HFILL }},
{ &hf_dvbs2_fragments,
{ "DVB-S2 GSE Fragments", "dvb-s2_gse.fragments", FT_BYTES, BASE_NONE,
NULL, 0x0, NULL, HFILL }},
{ &hf_dvbs2_reassembled_in,
{ "Reassembled DVB-S2 GSE in frame", "dvb-s2_gse.reassembled_in", FT_FRAMENUM, BASE_NONE,
NULL, 0x0, "This GSE packet is reassembled in this frame", HFILL }},
{ &hf_dvbs2_reassembled_length,
{ "Reassembled DVB-S2 GSE length", "dvb-s2_gse.reassembled.length", FT_UINT32, BASE_DEC,
NULL, 0x0, "The total length of the reassembled payload", HFILL }},
{ &hf_dvbs2_reassembled_data,
{ "Reassembled DVB-S2 GSE data", "dvb-s2_gse.reassembled.data", FT_BYTES, BASE_NONE,
NULL, 0x0, "The reassembled payload", HFILL }}
};
static gint *ett_gse[] = {
&ett_dvb_s2_gse,
&ett_dvb_s2_gse_hdr,
&ett_dvb_s2_gse_ncr
&ett_dvb_s2_gse_ncr,
&ett_dvbs2_fragments,
&ett_dvbs2_fragment,
};
static ei_register_info ei[] = {
@ -1584,6 +1705,8 @@ void proto_register_dvb_s2_modeadapt(void)
"Enable dissection of GSE data",
"Check this to enable full protocol dissection of data above GSE Layer",
&dvb_s2_full_dissection);
register_init_routine(dvbs2_defragment_init);
}
void proto_reg_handoff_dvb_s2_modeadapt(void)