I've managed to reuse some of the code in epan/dissectors/packet-fr.c that
hands off information to the osinl so that I could make
epan/dissectors/lapd.c act the same way. Everything appears to be working
correctly, however, I'm getting this bug and can't figure out why:
[Dissector bug, protocol LAPD: proto.c:2482: failed assertion
"(guint)hfindex < gpa_hfinfo.len"]
Expert Info (Error/Malformed): proto.c:2482: failed assertion
"(guint)hfindex < gpa_hfinfo.len"
Message: proto.c:2482: failed assertion "(guint)hfindex <
gpa_hfinfo.len"
Severity level: Error
Group: Malformed
Any suggestions as to what would cause this? Source file is attached.
Thanks,
Duff
/* packet-lapd.c
* Routines for LAPD frame disassembly
* Gilbert Ramirez <g...@alumni.rice.edu>
*
* $Id: packet-lapd.c 28356 2009-05-13 19:46:11Z etxrab $
*
* Wireshark - Network traffic analyzer
* By Gerald Combs <ger...@wireshark.org>
* Copyright 1998
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/
/*
* LAPD bitstream over RTP handling
* Copyright 2008, Ericsson AB
* Written by Balint Reczey <balint.rec...@ericsson.com>
*
* ISDN/LAPD references:
*
* http://www.cisco.com/univercd/cc/td/doc/cisintwk/ito_doc/isdn.htm
* http://www.ece.wpi.edu/courses/ee535/hwk11cd95/agrebe/agrebe.html
* http://www.acacia-net.com/Clarinet/Protocol/q9213o84.htm
* http://www.itu.int/rec/T-REC-Q.921/en
* Base Station Controller - Base Transceiver Station (BSC - BTS) interface;
Layer 2 specification
* http://www.3gpp.org/ftp/Specs/html-info/48056.htm
*/
#ifdef HAVE_CONFIG_H
# include "config.h"
#endif
#include <stdio.h>
#include <glib.h>
#include <string.h>
#include <epan/packet.h>
#include <epan/conversation.h>
#include <epan/xdlc.h>
#include <epan/crc16.h>
#include <epan/prefs.h>
#include <epan/lapd_sapi.h>
#include <epan/nlpid.h>
static int proto_lapd = -1;
static int hf_lapd_direction = -1;
static int hf_lapd_address = -1;
static int hf_lapd_sapi = -1;
static int hf_lapd_gsm_sapi = -1;
static int hf_lapd_cr = -1;
static int hf_lapd_ea1 = -1;
static int hf_lapd_tei = -1;
static int hf_lapd_ea2 = -1;
static int hf_lapd_control = -1;
static int hf_lapd_n_r = -1;
static int hf_lapd_n_s = -1;
static int hf_lapd_p = -1;
static int hf_lapd_p_ext = -1;
static int hf_lapd_f = -1;
static int hf_lapd_f_ext = -1;
static int hf_lapd_s_ftype = -1;
static int hf_lapd_u_modifier_cmd = -1;
static int hf_lapd_u_modifier_resp = -1;
static int hf_lapd_ftype_i = -1;
static int hf_lapd_ftype_s_u = -1;
static int hf_lapd_ftype_s_u_ext = -1;
static int hf_lapd_checksum = -1;
static int hf_lapd_checksum_good = -1;
static int hf_lapd_checksum_bad = -1;
/* duff */
static gint hf_lapd_nlpid = -1;
static gint hf_lapd_oui = -1;
static gint hf_lapd_pid = -1;
static gint hf_lapd_snaptype = -1;
/* duff */
static gint ett_lapd = -1;
static gint ett_lapd_address = -1;
static gint ett_lapd_control = -1;
static gint ett_lapd_checksum = -1;
static gint pref_lapd_rtp_payload_type = 0;
static dissector_table_t lapd_sapi_dissector_table;
static dissector_table_t lapd_gsm_sapi_dissector_table;
/* duff */
static dissector_table_t lapd_osinl_subdissector_table;
static dissector_table_t osinl_subdissector_table;
static dissector_table_t lapd_subdissector_table;
/* duff */
/* Whether to use GSM SAPI vals or not */
static gboolean global_lapd_gsm_sapis = FALSE;
static dissector_handle_t data_handle;
/*
* Bits in the address field.
*/
#define LAPD_SAPI 0xfc00 /* Service Access Point Identifier */
#define LAPD_SAPI_SHIFT 10
#define LAPD_CR 0x0200 /* Command/Response bit */
#define LAPD_EA1 0x0100 /* First Address Extension bit */
#define LAPD_TEI 0x00fe /* Terminal Endpoint Identifier */
#define LAPD_TEI_SHIFT 1
#define LAPD_EA2 0x0001 /* Second Address Extension bit */
static const value_string lapd_direction_vals[] = {
{ P2P_DIR_RECV, "Network->User"},
{ P2P_DIR_SENT, "User->Network"},
{ 0, NULL }
};
static const value_string lapd_sapi_vals[] = {
{ LAPD_SAPI_Q931, "Q.931 Call control procedure" },
{ LAPD_SAPI_PM_Q931, "Packet mode Q.931 Call control procedure" },
{ LAPD_SAPI_X25, "X.25 Level 3 procedures" },
{ LAPD_SAPI_L2, "Layer 2 management procedures" },
{ 0, NULL }
};
static const value_string lapd_gsm_sapi_vals[] = {
{ LAPD_GSM_SAPI_RA_SIG_PROC, "Radio signalling procedures" },
{ LAPD_GSM_SAPI_NOT_USED_1, "(Not used in GSM PLMN)" },
{ LAPD_GSM_SAPI_NOT_USED_16, "(Not used in GSM PLMN)" },
{ LAPD_GSM_SAPI_OM_PROC, "Operation and maintenance procedure" },
{ LAPD_SAPI_L2, "Layer 2 management procedures" },
{ 0, NULL }
};
static void dissect_lapd_nlpid(tvbuff_t *tvb, int offset, packet_info *pinfo,
proto_tree *tree, proto_item *ti,
proto_tree *fr_tree, guint16 fr_ctrl);
/* Used only for U frames */
static const xdlc_cf_items lapd_cf_items = {
NULL,
NULL,
&hf_lapd_p,
&hf_lapd_f,
NULL,
&hf_lapd_u_modifier_cmd,
&hf_lapd_u_modifier_resp,
NULL,
&hf_lapd_ftype_s_u
};
/* Used only for I and S frames */
static const xdlc_cf_items lapd_cf_items_ext = {
&hf_lapd_n_r,
&hf_lapd_n_s,
&hf_lapd_p_ext,
&hf_lapd_f_ext,
&hf_lapd_s_ftype,
NULL,
NULL,
&hf_lapd_ftype_i,
&hf_lapd_ftype_s_u_ext
};
/* LAPD frame detection state */
enum lapd_bitstream_states {OUT_OF_SYNC, FLAGS, DATA};
typedef struct lapd_byte_state {
enum lapd_bitstream_states state; /* frame detection state */
char full_byte; /* part of a full byte */
char bit_offset; /* number of bits already got
in the full byte */
int ones; /* number of consecutive ones
since the last zero */
} lapd_byte_state_t;
typedef struct lapd_ppi {
gboolean has_crc; /* CRC is captured with
LAPD the frames */
lapd_byte_state_t start_byte_state; /* LAPD bitstream byte
state at the beginnigng of processing the packet */
} lapd_ppi_t;
/* Fill values in lapd_byte_state struct */
static void
fill_lapd_byte_state(lapd_byte_state_t *ptr, enum lapd_bitstream_states state,
char full_byte, char bit_offset, int ones)
{
ptr->state = state;
ptr->full_byte = full_byte;
ptr->bit_offset = bit_offset;
ptr->ones = ones;
}
typedef struct lapd_convo_data {
address addr_a;
address addr_b;
guint32 port_a;
guint32 port_b;
lapd_byte_state_t *byte_state_a;
lapd_byte_state_t *byte_state_b;
} lapd_convo_data_t;
#define MAX_LAPD_PACKET_LEN 1024
static void
dissect_lapd(tvbuff_t*, packet_info*, proto_tree*);
/* got new LAPD frame byte */
static void new_byte(char full_byte, char data[], int *data_len) {
if (*data_len < MAX_LAPD_PACKET_LEN) {
data[*data_len] = full_byte;
(*data_len)++;
} else {
/* XXX : we are not prepared for that big messages, drop the
last byte */
}
}
static void
dissect_lapd_bitstream(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
{
guint8 byte, full_byte = 0x00, bit_offset = 0;
gboolean bit;
guint8 i, ones = 0, data[MAX_LAPD_PACKET_LEN];
int data_len = 0;
guint offset = 0, last_packet_end_offset = 0, available;
guint8 *buff;
tvbuff_t *new_tvb;
enum lapd_bitstream_states state = OUT_OF_SYNC;
lapd_ppi_t *lapd_ppi;
conversation_t *conversation = NULL;
lapd_convo_data_t *convo_data = NULL;
lapd_byte_state_t *lapd_byte_state, *prev_byte_state = NULL;
gboolean forward_stream = TRUE;
/* get remaining data from previous packets */
conversation = find_conversation(pinfo->fd->num, &pinfo->src,
&pinfo->dst,
pinfo->ptype, pinfo->srcport, pinfo->destport, 0);
lapd_ppi = (lapd_ppi_t*)p_get_proto_data(pinfo->fd, proto_lapd);
if (lapd_ppi) {
prev_byte_state = &lapd_ppi->start_byte_state;
if (prev_byte_state) {
state = prev_byte_state->state;
full_byte = prev_byte_state->full_byte;
bit_offset = prev_byte_state->bit_offset;
ones = prev_byte_state->ones;
}
} else if (conversation) {
convo_data =
(lapd_convo_data_t*)conversation_get_proto_data(conversation, proto_lapd);
if (NULL != convo_data) {
if (ADDRESSES_EQUAL(&convo_data->addr_a, &pinfo->src)
&& ADDRESSES_EQUAL(&convo_data->addr_b,
&pinfo->dst)
&& convo_data-> port_a == pinfo->srcport
&& convo_data-> port_b ==
pinfo->destport) {
/* "forward" direction */
forward_stream = TRUE;
prev_byte_state = convo_data->byte_state_a;
} else if (ADDRESSES_EQUAL(&convo_data-> addr_b,
&pinfo->src)
&& ADDRESSES_EQUAL(&convo_data->addr_a,
&pinfo->dst)
&& convo_data-> port_b == pinfo->srcport
&& convo_data-> port_a ==
pinfo->destport) {
/* "backward" direction */
forward_stream = FALSE;
prev_byte_state = convo_data->byte_state_b;
}
}
if (prev_byte_state) {
state = prev_byte_state->state;
full_byte = prev_byte_state->full_byte;
bit_offset = prev_byte_state->bit_offset;
ones = prev_byte_state->ones;
}
}
/* Consume tvb bytes */
available = tvb_length_remaining(tvb, offset);
while (offset < available) {
byte = tvb_get_guint8(tvb,offset);
offset++;
for (i=0; i < 8; i++) { /* cycle through bits */
bit = byte & (0x80 >> i) ? TRUE : FALSE;
/* consume a bit */
if (bit) {
ones++;
full_byte |= (1 << bit_offset++);
} else {
if (ones == 5 && state == DATA) {
/* we don't increase bit_offset, it is
an inserted zero */
} else if (ones == 6 && state == DATA) { /*
probably starting flag sequence */
buff = g_memdup(data, data_len);
/* Allocate new tvb for the LAPD frame
*/
new_tvb = tvb_new_child_real_data(tvb,
buff, data_len, data_len);
tvb_set_free_cb(new_tvb, g_free);
add_new_data_source(pinfo, new_tvb,
"Decoded LAPD bitstream");
dissect_lapd(new_tvb, pinfo, tree);
last_packet_end_offset = offset -1;
data_len = 0;
state = FLAGS;
bit_offset++;
} else if (ones >= 7) { /* frame reset or
11111111 flag byte */
data_len = 0;
state = OUT_OF_SYNC;
bit_offset++;
} else {
bit_offset++;
}
ones = 0;
}
if (bit_offset == 8) { /* we have a new complete byte */
switch (state) {
case OUT_OF_SYNC:
if (full_byte == 0x7E) { /* we
have a flag byte */
state = FLAGS;
full_byte = 0x00;
bit_offset = 0;
} else { /* no sync yet, wait
for a new byte */
full_byte = (full_byte
>> 1) & 0x7F;
bit_offset--;
}
break;
case FLAGS:
if (full_byte == 0x7E) { /* we
have a flag byte */
full_byte = 0x00;
bit_offset = 0;
} else { /* we got the first
data byte */
state = DATA;
new_byte(full_byte,
data, &data_len);
full_byte = 0x00;
bit_offset = 0;
}
break;
case DATA:
/* we got a new data byte */
new_byte(full_byte, data,
&data_len);
full_byte = 0x00;
bit_offset = 0;
break;
}
}
}
}
if (state == DATA) { /* we are in the middle of an LAPD frame, we need
more bytes */
pinfo->desegment_offset = 0;
pinfo->desegment_len = DESEGMENT_ONE_MORE_SEGMENT;
return;
} else { /* finished processing LAPD frame(s) */
if (NULL == p_get_proto_data(pinfo->fd, proto_lapd)) {
/* Per packet information */
lapd_ppi = g_malloc(sizeof(lapd_ppi_t));
lapd_ppi->has_crc = TRUE;
if (prev_byte_state)
fill_lapd_byte_state(&lapd_ppi->start_byte_state, prev_byte_state->state,
prev_byte_state->full_byte,
prev_byte_state->bit_offset,
prev_byte_state->ones);
else
fill_lapd_byte_state(&lapd_ppi->start_byte_state, OUT_OF_SYNC, 0x00, 0, 0);
p_add_proto_data(pinfo->fd, proto_lapd, lapd_ppi);
/* Conversation info*/
if (conversation) {
if (convo_data) { /* already have lapd convo
data */
if (forward_stream)
fill_lapd_byte_state(convo_data->byte_state_a, state, full_byte, bit_offset,
ones);
else {
if (!convo_data->byte_state_b)
convo_data->byte_state_b = g_malloc(sizeof(lapd_byte_state_t));
fill_lapd_byte_state(convo_data->byte_state_b, state, full_byte, bit_offset,
ones);
}
} else { /* lapd convo data has to be created */
lapd_byte_state =
g_malloc(sizeof(lapd_byte_state_t));
fill_lapd_byte_state(lapd_byte_state,
state, full_byte, bit_offset, ones);
convo_data =
g_malloc(sizeof(lapd_convo_data_t));
COPY_ADDRESS(&convo_data->addr_a,
&pinfo->src);
COPY_ADDRESS(&convo_data->addr_b,
&pinfo->dst);
convo_data->port_a = pinfo->srcport;
convo_data->port_b = pinfo->destport;
convo_data->byte_state_a =
lapd_byte_state;
convo_data->byte_state_b = NULL;
conversation_add_proto_data(conversation, proto_lapd, convo_data);
}
}
}
}
}
/* duff */
static void dissect_lapd_nlpid(tvbuff_t *tvb, int offset, packet_info *pinfo,
proto_tree *tree, proto_item *ti,
proto_tree *lapd_tree, guint16 lapd_ctrl)
{
guint8 lapd_nlpid;
tvbuff_t *next_tvb;
/*
* Tentatively set the Frame Relay item not to include the NLPID,
* as OSI network layer protocols consider it to be part of
* the OSI PDU.
*/
proto_item_set_end(ti, tvb, offset);
lapd_nlpid = tvb_get_guint8 (tvb,offset);
if (lapd_nlpid == 0) {
if (tree)
proto_tree_add_text(lapd_tree, tvb, offset, 1, "Padding");
offset++;
if (ti != NULL) {
/* Include the padding in the top-level protocol tree item. */
proto_item_set_end(ti, tvb, offset);
}
lapd_nlpid=tvb_get_guint8( tvb,offset);
}
/*
* OSI network layer protocols consider the NLPID to be part
* of the frame, so we'll pass it as part of the payload and,
* if the protocol is one of those, add it as a hidden item here.
* We check both the generic OSI NLPID dissector table and
* the Frame Relay OSI NLPID dissector table - the latter is for
* NLPID's such as 0x08, which is Q.933 in Frame Relay but
* other protocols (e.g., Q.931) on other network layers.
*
* "OSI network layer protocols" includes Q.933.
*
* XXX - note that an NLPID of 0x08 for Q.933 could either be a
* Q.933 signaling message or a message for a protocol
* identified by a 2-octet layer 2 protocol type and a
* 2-octet layer 3 protocol type, those protocol type
* octets having the values from octets 6, 6a, 7, and 7a
* of a Q.931 low layer compatibility information element
* (section 4.5.19 of Q.931; Q.933 says they have the values
* from a Q.933 low layer compatibility information element,
* but Q.933 low layer compatibility information elements
* don't have protocol values in them).
*
* Assuming that, as Q.933 seems to imply, that Q.933 messages
* look just like Q.931 messages except where it explicitly
* says they differ, then the octet after the NLPID would,
* in a Q.933 message, have its upper 4 bits zero (that's
* the length of the call reference value, in Q.931, and
* is limited to 15 or fewer octets). As appears to be the case,
* octet 6 of a Q.931 low layer compatibility element has the
* 0x40 bit set, so you can distinguish between a Q.933
* message and an encapsulated packet by checking whether
* the upper 4 bits of the octet after the NLPID are zero.
*
* Either that, or it's Q.933 iff the DLCI is 0.
*/
next_tvb = tvb_new_subset(tvb,offset,-1,-1);
//next_tvb = tvb_new_subset(tvb, offset, tvb_length_remaining(tvb,offset)-1,
-1);
if (dissector_try_port(osinl_subdissector_table, lapd_nlpid, next_tvb,
pinfo, tree) ||
dissector_try_port(lapd_osinl_subdissector_table, lapd_nlpid, next_tvb,
pinfo, tree)) {
/*
* Yes, we got a match. Add the NLPID as a hidden item,
* so you can, at least, filter on it.
*/
if (tree) {
proto_item *hidden_item;
hidden_item = proto_tree_add_uint(lapd_tree, hf_lapd_nlpid,
tvb, offset, 1, lapd_nlpid );
PROTO_ITEM_SET_HIDDEN(hidden_item);
}
return;
}
/*
* All other protocols don't.
*
* XXX - what about Cisco/Gang-of-Four LMI? Is the 0x09 considered
* to be part of the LMI PDU?
*/
if (tree)
proto_tree_add_uint(lapd_tree, hf_lapd_nlpid, tvb, offset, 1,
lapd_nlpid );
offset++;
switch (lapd_nlpid) {
// case NLPID_SNAP:
// if (ti != NULL) {
// /* Include the NLPID and SNAP header in the top-level
// protocol tree item. */
// proto_item_set_end(ti, tvb, offset+5);
// }
// dissect_snap(tvb, offset, pinfo, tree, lapd_tree, lapd_ctrl,
// hf_lapd_oui, hf_lapd_snaptype, hf_lapd_pid, 0);
// return;
default:
if (ti != NULL) {
/* Include the NLPID in the top-level protocol tree item. */
proto_item_set_end(ti, tvb, offset);
}
next_tvb = tvb_new_subset(tvb,offset,-1,-1);
//next_tvb = tvb_new_subset(tvb, offset,
tvb_length_remaining(tvb,offset) - 3, -1);
if (!dissector_try_port(lapd_subdissector_table,lapd_nlpid,
next_tvb, pinfo, tree))
call_dissector(data_handle,next_tvb, pinfo, tree);
break;
}
}
/* duff */
static void
dissect_lapd(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
{
proto_tree *lapd_tree, *addr_tree, *checksum_tree;
proto_item *lapd_ti, *addr_ti, *checksum_ti;
int direction;
guint16 control, checksum, checksum_calculated;
int lapd_header_len, checksum_offset;
guint16 address, cr, sapi, tei;
gboolean is_response = 0;
tvbuff_t *next_tvb;
const char *srcname = "?";
const char *dstname = "?";
if (check_col(pinfo->cinfo, COL_PROTOCOL))
col_set_str(pinfo->cinfo, COL_PROTOCOL, "LAPD_DUFF");
if (check_col(pinfo->cinfo, COL_INFO))
col_clear(pinfo->cinfo, COL_INFO);
address = tvb_get_ntohs(tvb, 0);
cr = address & LAPD_CR;
tei = (address & LAPD_TEI) >> LAPD_TEI_SHIFT;
sapi = (address & LAPD_SAPI) >> LAPD_SAPI_SHIFT;
lapd_header_len = 2; /* address */
if (check_col(pinfo->cinfo, COL_TEI))
col_add_fstr(pinfo->cinfo, COL_TEI, "%u", tei);
if (pinfo->fd->lnk_t == WTAP_ENCAP_LINUX_LAPD) {
/* frame is captured via libpcap */
if (pinfo->pseudo_header->lapd.pkttype == 4
/*PACKET_OUTGOING*/) {
if (pinfo->pseudo_header->lapd.we_network) {
is_response = cr ? FALSE : TRUE;
srcname = "Local Network";
dstname = "Remote User";
direction = P2P_DIR_RECV; /*
Network->User */
} else {
srcname = "Local User";
dstname = "Remote Network";
direction = P2P_DIR_SENT; /*
User->Network */
}
}
else if (pinfo->pseudo_header->lapd.pkttype == 3
/*PACKET_OTHERHOST*/) {
/* We must be a TE, sniffing what other TE transmit */
is_response = cr ? TRUE : FALSE;
srcname = "Remote User";
dstname = "Remote Network";
direction = P2P_DIR_SENT; /* User->Network */
}
else {
/* The frame is incoming */
if (pinfo->pseudo_header->lapd.we_network) {
is_response = cr ? TRUE : FALSE;
srcname = "Remote User";
dstname = "Local Network";
direction = P2P_DIR_SENT; /*
User->Network */
} else {
is_response = cr ? FALSE : TRUE;
srcname = "Remote Network";
dstname = "Local User";
direction = P2P_DIR_RECV; /*
Network->User */
}
}
} else {
direction = pinfo->p2p_dir;
if (pinfo->p2p_dir == P2P_DIR_RECV) {
is_response = cr ? FALSE : TRUE;
srcname = "Network";
dstname = "User";
}
else if (pinfo->p2p_dir == P2P_DIR_SENT) {
is_response = cr ? TRUE : FALSE;
srcname = "User";
dstname = "Network";
}
}
if(check_col(pinfo->cinfo, COL_RES_DL_SRC))
col_set_str(pinfo->cinfo, COL_RES_DL_SRC, srcname);
if(check_col(pinfo->cinfo, COL_RES_DL_DST))
col_set_str(pinfo->cinfo, COL_RES_DL_DST, dstname);
if (tree) {
proto_item *direction_ti;
lapd_ti = proto_tree_add_item(tree, proto_lapd, tvb, 0, -1,
FALSE);
lapd_tree = proto_item_add_subtree(lapd_ti, ett_lapd);
/*
* Don't show the direction if we don't know it.
*/
if (direction != P2P_DIR_UNKNOWN) {
direction_ti = proto_tree_add_uint(lapd_tree,
hf_lapd_direction,
tvb, 0, 0,
pinfo->p2p_dir);
PROTO_ITEM_SET_GENERATED(direction_ti);
}
addr_ti = proto_tree_add_uint(lapd_tree, hf_lapd_address, tvb,
0, 2, address);
addr_tree = proto_item_add_subtree(addr_ti, ett_lapd_address);
if(global_lapd_gsm_sapis){
proto_tree_add_uint(addr_tree, hf_lapd_gsm_sapi,tvb, 0,
1, address);
}else{
proto_tree_add_uint(addr_tree, hf_lapd_sapi,tvb, 0, 1,
address);
}
proto_tree_add_uint(addr_tree, hf_lapd_cr, tvb, 0, 1, address);
proto_tree_add_uint(addr_tree, hf_lapd_ea1, tvb, 0, 1, address);
proto_tree_add_uint(addr_tree, hf_lapd_tei, tvb, 1, 1, address);
proto_tree_add_uint(addr_tree, hf_lapd_ea2, tvb, 1, 1, address);
}
else {
lapd_ti = NULL;
lapd_tree = NULL;
}
control = dissect_xdlc_control(tvb, 2, pinfo, lapd_tree,
hf_lapd_control,
ett_lapd_control, &lapd_cf_items, &lapd_cf_items_ext, NULL, NULL,
is_response, TRUE, FALSE);
lapd_header_len += XDLC_CONTROL_LEN(control, TRUE);
if (tree)
proto_item_set_len(lapd_ti, lapd_header_len);
if (NULL != p_get_proto_data(pinfo->fd, proto_lapd)
&& ((lapd_ppi_t*)p_get_proto_data(pinfo->fd,
proto_lapd))->has_crc) {
/* check checksum */
checksum_offset = tvb_length(tvb) - 2;
checksum = tvb_get_guint8(tvb, checksum_offset); /* high byte */
checksum <<= 8;
checksum |= tvb_get_guint8(tvb, checksum_offset+1) & 0x00FF; /*
low byte */
checksum_calculated = g_htons(crc16_ccitt_tvb(tvb,
tvb_length(tvb) - 2));
if (checksum == checksum_calculated) {
checksum_ti = proto_tree_add_uint_format(lapd_tree,
hf_lapd_checksum, tvb, checksum_offset, 2, 0,"Checksum: 0x%04x [correct]",
checksum);
checksum_tree = proto_item_add_subtree(checksum_ti,
ett_lapd_checksum);
proto_tree_add_boolean(checksum_tree,
hf_lapd_checksum_good, tvb, checksum_offset, 2, TRUE);
proto_tree_add_boolean(checksum_tree,
hf_lapd_checksum_bad, tvb, checksum_offset, 2, FALSE);
} else {
checksum_ti = proto_tree_add_uint_format(lapd_tree,
hf_lapd_checksum, tvb, checksum_offset, 2, 0,"Checksum: 0x%04x [incorrect,
should be 0x%04x]", checksum, checksum_calculated);
checksum_tree = proto_item_add_subtree(checksum_ti,
ett_lapd_checksum);
proto_tree_add_boolean(checksum_tree,
hf_lapd_checksum_good, tvb, checksum_offset, 2, FALSE);
proto_tree_add_boolean(checksum_tree,
hf_lapd_checksum_bad, tvb, checksum_offset, 2, TRUE);
}
next_tvb = tvb_new_subset(tvb, lapd_header_len,
tvb_length_remaining(tvb,lapd_header_len) - 2, -1);
} else
next_tvb = tvb_new_subset(tvb, lapd_header_len, -1, -1);
/*duff*/
//next_tvb = tvb_new_subset(tvb, lapd_header_len,
tvb_length_remaining(tvb,lapd_header_len) - 3, -1);
next_tvb = tvb_new_subset(tvb, lapd_header_len, -1, -1);
if (tvb_length_remaining(tvb,lapd_header_len) - 3 > 0)
{
dissect_lapd_nlpid(next_tvb, 0, pinfo, tree, lapd_ti,
lapd_tree, control);
}
/*duff*/
if (XDLC_IS_INFORMATION(control)) {
/* call next protocol */
if(global_lapd_gsm_sapis){
if (!dissector_try_port(lapd_gsm_sapi_dissector_table,
sapi,
next_tvb, pinfo, tree))
call_dissector(data_handle,next_tvb, pinfo,
tree);
}else{
if (!dissector_try_port(lapd_sapi_dissector_table, sapi,
next_tvb, pinfo, tree))
call_dissector(data_handle,next_tvb, pinfo,
tree);
}
} else
call_dissector(data_handle,next_tvb, pinfo, tree);
}
void
proto_reg_handoff_lapd(void);
void
proto_register_lapd(void)
{
static hf_register_info hf[] = {
{ &hf_lapd_direction,
{ "Direction", "lapd.direction", FT_UINT8, BASE_DEC,
VALS(lapd_direction_vals), 0x0,
NULL, HFILL }},
{ &hf_lapd_address,
{ "Address Field", "lapd.address", FT_UINT16, BASE_HEX, NULL, 0x0,
"Address", HFILL }},
{ &hf_lapd_sapi,
{ "SAPI", "lapd.sapi", FT_UINT16, BASE_DEC, VALS(lapd_sapi_vals),
LAPD_SAPI,
"Service Access Point Identifier", HFILL }},
{ &hf_lapd_gsm_sapi,
{ "SAPI", "lapd.sapi", FT_UINT16, BASE_DEC, VALS(lapd_gsm_sapi_vals),
LAPD_SAPI,
"Service Access Point Identifier", HFILL }},
{ &hf_lapd_cr,
{ "C/R", "lapd.cr", FT_UINT16, BASE_DEC, NULL, LAPD_CR,
"Command/Response bit", HFILL }},
{ &hf_lapd_ea1,
{ "EA1", "lapd.ea1", FT_UINT16, BASE_DEC, NULL, LAPD_EA1,
"First Address Extension bit", HFILL }},
{ &hf_lapd_tei,
{ "TEI", "lapd.tei", FT_UINT16, BASE_DEC, NULL, LAPD_TEI,
"Terminal Endpoint Identifier", HFILL }},
{ &hf_lapd_ea2,
{ "EA2", "lapd.ea2", FT_UINT16, BASE_DEC, NULL, LAPD_EA2,
"Second Address Extension bit", HFILL }},
{ &hf_lapd_control,
{ "Control Field", "lapd.control", FT_UINT16, BASE_HEX, NULL, 0x0,
"Control field", HFILL }},
{ &hf_lapd_n_r,
{ "N(R)", "lapd.control.n_r", FT_UINT16, BASE_DEC,
NULL, XDLC_N_R_EXT_MASK, NULL, HFILL }},
{ &hf_lapd_n_s,
{ "N(S)", "lapd.control.n_s", FT_UINT16, BASE_DEC,
NULL, XDLC_N_S_EXT_MASK, NULL, HFILL }},
{ &hf_lapd_p,
{ "Poll", "lapd.control.p", FT_BOOLEAN, 8,
TFS(&flags_set_truth), XDLC_P_F, NULL, HFILL }},
{ &hf_lapd_p_ext,
{ "Poll", "lapd.control.p", FT_BOOLEAN, 16,
TFS(&flags_set_truth), XDLC_P_F_EXT, NULL, HFILL }},
{ &hf_lapd_f,
{ "Final", "lapd.control.f", FT_BOOLEAN, 8,
TFS(&flags_set_truth), XDLC_P_F, NULL, HFILL }},
{ &hf_lapd_f_ext,
{ "Final", "lapd.control.f", FT_BOOLEAN, 16,
TFS(&flags_set_truth), XDLC_P_F_EXT, NULL, HFILL }},
{ &hf_lapd_s_ftype,
{ "Supervisory frame type", "lapd.control.s_ftype", FT_UINT16,
BASE_HEX,
VALS(stype_vals), XDLC_S_FTYPE_MASK, NULL, HFILL }},
{ &hf_lapd_u_modifier_cmd,
{ "Command", "lapd.control.u_modifier_cmd", FT_UINT8, BASE_HEX,
VALS(modifier_vals_cmd), XDLC_U_MODIFIER_MASK, NULL, HFILL }},
{ &hf_lapd_u_modifier_resp,
{ "Response", "lapd.control.u_modifier_resp", FT_UINT8, BASE_HEX,
VALS(modifier_vals_resp), XDLC_U_MODIFIER_MASK, NULL, HFILL }},
{ &hf_lapd_ftype_i,
{ "Frame type", "lapd.control.ftype", FT_UINT16, BASE_HEX,
VALS(ftype_vals), XDLC_I_MASK, NULL, HFILL }},
{ &hf_lapd_ftype_s_u,
{ "Frame type", "lapd.control.ftype", FT_UINT8, BASE_HEX,
VALS(ftype_vals), XDLC_S_U_MASK, NULL, HFILL }},
{ &hf_lapd_ftype_s_u_ext,
{ "Frame type", "lapd.control.ftype", FT_UINT16, BASE_HEX,
VALS(ftype_vals), XDLC_S_U_MASK, NULL, HFILL }},
{ &hf_lapd_checksum,
{ "Checksum", "lapd.checksum", FT_UINT16, BASE_HEX,
NULL, 0x0, "Details at:
http://www.wireshark.org/docs/wsug_html_chunked/ChAdvChecksums.html";, HFILL }},
{ &hf_lapd_checksum_good,
{ "Good Checksum", "lapd.checksum_good", FT_BOOLEAN, BASE_NONE,
NULL, 0x0, "True: checksum matches packet content; False:
doesn't match content or not checked", HFILL }},
{ &hf_lapd_checksum_bad,
{ "Bad Checksum", "lapd.checksum_bad", FT_BOOLEAN, BASE_NONE,
NULL, 0x0, "True: checksum doesn't match packet content; False:
matches content or not checked", HFILL }}
};
static gint *ett[] = {
&ett_lapd,
&ett_lapd_address,
&ett_lapd_control,
&ett_lapd_checksum
};
module_t *lapd_module;
proto_lapd = proto_register_protocol("Link Access Procedure, Channel D
(LAPD)",
"LAPD", "lapd");
proto_register_field_array (proto_lapd, hf, array_length(hf));
proto_register_subtree_array(ett, array_length(ett));
/* duff */
lapd_subdissector_table = register_dissector_table("lapd.ietf",
"LAPD NLPID", FT_UINT8, BASE_HEX);
lapd_osinl_subdissector_table = register_dissector_table("lapd.osinl",
"LAPD OSI NLPID", FT_UINT8, BASE_HEX);
/* duff */
register_dissector("lapd", dissect_lapd, proto_lapd);
lapd_sapi_dissector_table = register_dissector_table("lapd.sapi",
"LAPD SAPI",
FT_UINT16, BASE_DEC);
lapd_gsm_sapi_dissector_table =
register_dissector_table("lapd.gsm.sapi",
"LAPD GSM
SAPI", FT_UINT16, BASE_DEC);
lapd_module = prefs_register_protocol(proto_lapd,
proto_reg_handoff_lapd);
prefs_register_bool_preference(lapd_module, "use_gsm_sapi_values",
"Use GSM SAPI values",
"Use SAPI values as specified in TS 48 056",
&global_lapd_gsm_sapis);
prefs_register_uint_preference(lapd_module, "rtp_payload_type",
"RTP payload type for embedded LAPD",
"RTP payload type for embedded LAPD. It must be one of the
dynamic types "
"from 96 to 127. Set it to 0 to disable.",
10, &pref_lapd_rtp_payload_type);
}
void
proto_reg_handoff_lapd(void)
{
static gboolean init = FALSE;
static dissector_handle_t lapd_bitstream_handle;
static gint lapd_rtp_payload_type;
if (!init) {
dissector_handle_t lapd_handle;
lapd_handle = find_dissector("lapd");
dissector_add("wtap_encap", WTAP_ENCAP_LINUX_LAPD, lapd_handle);
lapd_bitstream_handle =
create_dissector_handle(dissect_lapd_bitstream, proto_lapd);
data_handle = find_dissector("data");
/* duff */
osinl_subdissector_table = find_dissector_table("osinl");
/* duff */
init = TRUE;
} else {
if ((lapd_rtp_payload_type > 95) && (lapd_rtp_payload_type <
128))
dissector_delete("rtp.pt", lapd_rtp_payload_type,
lapd_bitstream_handle);
}
lapd_rtp_payload_type = pref_lapd_rtp_payload_type;
if ((lapd_rtp_payload_type > 95) && (lapd_rtp_payload_type < 128))
dissector_add("rtp.pt", lapd_rtp_payload_type,
lapd_bitstream_handle);
}
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