![Michael Mann](/assets/img/avatar_default.png)
This is an attempt to standardize display/handling of checksum fields for all dissectors. The main target is for dissectors that do validation, but dissectors that just report the checksum were also included just to make them easier to find in the future. Bug: 10620 Bug: 12058 Ping-Bug: 8859 Change-Id: Ia8abd86e42eaf8ed50de6b173409e914b17993bf Reviewed-on: https://code.wireshark.org/review/16380 Petri-Dish: Michael Mann <mmann78@netscape.net> Tested-by: Petri Dish Buildbot <buildbot-no-reply@wireshark.org> Reviewed-by: Jeff Morriss <jeff.morriss.ws@gmail.com> Reviewed-by: Michael Mann <mmann78@netscape.net>
260 lines
7.7 KiB
C
260 lines
7.7 KiB
C
/* packet-gdb.c
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* Routines for dissection of GDB's Remote Serial Protocol
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*
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* Copyright 2014, Martin Kaiser <martin@kaiser.cx>
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*
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* Wireshark - Network traffic analyzer
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* By Gerald Combs <gerald@wireshark.org>
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* Copyright 1998 Gerald Combs
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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/*
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* The GDB Remote Serial Protocol is used between an instance of the
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* GNU Debugger and a remote target such as an embedded system.
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* It can be run over TCP/IP or a serial line, we support only TCP/IP.
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*
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* The protocol specification is in Annex E of the GDB user manual
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* http://www.gnu.org/software/gdb/documentation/
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*
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*/
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#include "config.h"
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#include <epan/packet.h>
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#include <epan/tvbparse.h>
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enum {
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GDB_TOK_ACK,
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GDB_TOK_START,
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GDB_TOK_PAYLOAD,
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GDB_TOK_END,
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GDB_TOK_CHKSUM
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};
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static const value_string gdb_ack[] = {
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{ '+', "Transmission successful" },
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{ '-', "Transmission failed" },
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{ 0, NULL }
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};
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void proto_register_gdb(void);
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void proto_reg_handoff_gdb(void);
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static int proto_gdb = -1;
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static gint ett_gdb = -1;
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static int hf_gdb_ack = -1;
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static int hf_gdb_start = -1;
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static int hf_gdb_payload = -1;
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static int hf_gdb_end = -1;
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static int hf_gdb_chksum = -1;
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static tvbparse_wanted_t *want;
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static void
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dissect_gdb_token(void *tvbparse_data, const void *wanted_data, tvbparse_elem_t *tok)
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{
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proto_tree *tree;
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guint token;
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guint8 ack;
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if (!tok) /* XXX - is this check necessary? */
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return;
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tree = (proto_tree *)tvbparse_data;
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token = GPOINTER_TO_UINT(wanted_data);
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/* XXX - check that tok->len is what we expect? */
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switch (token) {
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case GDB_TOK_ACK:
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ack = tvb_get_guint8(tok->tvb, tok->offset);
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proto_tree_add_uint_format(tree, hf_gdb_ack,
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tok->tvb, tok->offset, tok->len, ack,
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"Acknowledgement: %s (%c)",
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val_to_str_const(ack, gdb_ack, "unknown"), ack);
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break;
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case GDB_TOK_START:
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proto_tree_add_item(tree, hf_gdb_start,
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tok->tvb, tok->offset, tok->len, ENC_ASCII|ENC_NA);
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break;
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case GDB_TOK_PAYLOAD:
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proto_tree_add_item(tree, hf_gdb_payload,
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tok->tvb, tok->offset, tok->len, ENC_NA);
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break;
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case GDB_TOK_END:
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proto_tree_add_item(tree, hf_gdb_end,
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tok->tvb, tok->offset, tok->len, ENC_ASCII|ENC_NA);
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break;
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case GDB_TOK_CHKSUM:
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/* the spec is not really explicit but it seems that the
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checksum is big endian */
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proto_tree_add_checksum(tree, tok->tvb, tok->offset, hf_gdb_chksum, -1, NULL, NULL, 0, ENC_BIG_ENDIAN, PROTO_CHECKSUM_NO_FLAGS);
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break;
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default:
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break;
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}
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}
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static void init_gdb_parser(void) {
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tvbparse_wanted_t *want_ack;
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tvbparse_wanted_t *want_start;
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tvbparse_wanted_t *want_payload;
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tvbparse_wanted_t *want_end;
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tvbparse_wanted_t *want_chksum;
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want_ack = tvbparse_chars(-1, 1, 1, "+-",
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GUINT_TO_POINTER(GDB_TOK_ACK), NULL, dissect_gdb_token);
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want_start = tvbparse_chars(-1, 1, 1, "$",
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GUINT_TO_POINTER(GDB_TOK_START), NULL, dissect_gdb_token);
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want_payload = tvbparse_not_chars(-1, 1, 0, "$#",
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GUINT_TO_POINTER(GDB_TOK_PAYLOAD), NULL, dissect_gdb_token);
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want_end = tvbparse_chars(-1, 1, 1, "#",
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GUINT_TO_POINTER(GDB_TOK_END), NULL, dissect_gdb_token);
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want_chksum = tvbparse_chars(-1, 2, 2, "0123456789abcdefABCDEF",
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GUINT_TO_POINTER(GDB_TOK_CHKSUM), NULL, dissect_gdb_token);
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want = tvbparse_set_seq(-1, NULL, NULL, NULL,
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tvbparse_some(-1, 0, 1, NULL, NULL, NULL, want_ack),
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want_start, want_payload, want_end, want_chksum, NULL);
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}
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static void
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dissect_gdb_packet(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
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{
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proto_item *ti;
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proto_tree *gdb_tree;
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tvbparse_t *tt;
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col_set_str(pinfo->cinfo, COL_PROTOCOL, "GDB");
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col_clear(pinfo->cinfo, COL_INFO);
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ti = proto_tree_add_protocol_format(tree, proto_gdb,
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tvb, 0, tvb_reported_length(tvb), "GDB Remote Serial Protocol");
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gdb_tree = proto_item_add_subtree(ti, ett_gdb);
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/* XXX support multiple sub-trees */
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tt = tvbparse_init(tvb, 0, -1, (void *)gdb_tree, NULL);
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while(tvbparse_get(tt, want)) {
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;
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}
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}
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static int
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dissect_gdb_tcp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
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{
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gint offset=0, offset_start;
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gint pos;
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guint packet_len;
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tvbuff_t *packet_tvb;
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while (tvb_captured_length_remaining(tvb, offset) > 0) {
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packet_tvb = NULL;
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offset_start = offset;
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pos = tvb_find_guint8(tvb, offset, -1, '#');
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if (pos != -1) {
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offset += pos;
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offset++; /* skip the hash sign */
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/* to have a complete packet, we need another two bytes
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for the checksum */
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if (tvb_bytes_exist(tvb, offset, 2)) {
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offset += 2;
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packet_len = offset-offset_start;
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packet_tvb = tvb_new_subset_length(tvb, offset_start,
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packet_len);
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}
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}
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if (packet_tvb)
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dissect_gdb_packet(tvb, pinfo, tree);
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else {
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pinfo->desegment_offset = offset;
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pinfo->desegment_len = DESEGMENT_ONE_MORE_SEGMENT;
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return tvb_captured_length(tvb);
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}
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}
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return tvb_captured_length(tvb);
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}
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void
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proto_register_gdb(void)
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{
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static hf_register_info hf[] = {
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{ &hf_gdb_ack,
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{ "Acknowledge", "gdb.ack", FT_UINT8, BASE_HEX,
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VALS(gdb_ack), 0, NULL, HFILL } },
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{ &hf_gdb_start,
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{ "Start character", "gdb.start", FT_STRING, BASE_NONE,
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NULL, 0, NULL, HFILL } },
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{ &hf_gdb_payload,
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{ "Payload", "gdb.payload", FT_BYTES, BASE_NONE,
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NULL, 0, NULL, HFILL } },
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{ &hf_gdb_end,
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{ "Terminating character", "gdb.end", FT_STRING, BASE_NONE,
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NULL, 0, NULL, HFILL } },
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{ &hf_gdb_chksum,
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{ "Checksum", "gdb.chksum", FT_UINT8, BASE_HEX,
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NULL, 0, NULL, HFILL } }
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};
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static gint *ett[] = {
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&ett_gdb
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};
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proto_gdb = proto_register_protocol(
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"GDB Remote Serial Protocol", "GDB remote", "gdb");
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proto_register_field_array(proto_gdb, hf, array_length(hf));
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proto_register_subtree_array(ett, array_length(ett));
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init_gdb_parser();
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}
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void
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proto_reg_handoff_gdb(void)
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{
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static gboolean initialized = FALSE;
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static dissector_handle_t gdb_handle;
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if (!initialized) {
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gdb_handle = create_dissector_handle(dissect_gdb_tcp, proto_gdb);
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initialized = TRUE;
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}
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dissector_add_for_decode_as("tcp.port", gdb_handle);
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}
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/*
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* Editor modelines - http://www.wireshark.org/tools/modelines.html
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*
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* Local variables:
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* c-basic-offset: 4
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* tab-width: 8
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* indent-tabs-mode: nil
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* End:
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*
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* vi: set shiftwidth=4 tabstop=8 expandtab:
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* :indentSize=4:tabSize=8:noTabs=true:
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*/
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