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wireshark/epan/dissectors/packet-user_encap.c

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/* packet-user_encap.c
* Allow users to specify the dissectors for DLTs
* Luis E. Garcia Ontanon <luis@ontanon.org>
*
* Wireshark - Network traffic analyzer
* By Gerald Combs <gerald@wireshark.org>
* Copyright 1998
*
* SPDX-License-Identifier: GPL-2.0-or-later
*/
#include "config.h"
#include <epan/packet.h>
#include <epan/expert.h>
#include <epan/prefs.h>
#include <epan/uat.h>
#include <epan/exported_pdu.h>
#include <epan/tap.h>
#include <wiretap/wtap.h>
#ifdef _MSC_VER
/* disable: warning C4090: 'XY' : different 'const' qualifiers */
#pragma warning(disable:4090)
#endif
void proto_register_user_encap(void);
void proto_reg_handoff_user_encap(void);
typedef struct _user_encap_t {
guint encap;
char* payload_proto_name;
dissector_handle_t payload_proto;
char* header_proto_name;
dissector_handle_t header_proto;
char* trailer_proto_name;
dissector_handle_t trailer_proto;
guint header_size;
guint trailer_size;
} user_encap_t;
#define ENCAP0_STR "User 0 (DLT=147)"
static const value_string user_dlts[] = {
{ WTAP_ENCAP_USER0, ENCAP0_STR},
{ WTAP_ENCAP_USER1, "User 1 (DLT=148)"},
{ WTAP_ENCAP_USER2, "User 2 (DLT=149)"},
{ WTAP_ENCAP_USER3, "User 3 (DLT=150)"},
{ WTAP_ENCAP_USER4, "User 4 (DLT=151)"},
{ WTAP_ENCAP_USER5, "User 5 (DLT=152)"},
{ WTAP_ENCAP_USER6, "User 6 (DLT=153)"},
{ WTAP_ENCAP_USER7, "User 7 (DLT=154)"},
{ WTAP_ENCAP_USER8, "User 8 (DLT=155)"},
{ WTAP_ENCAP_USER9, "User 9 (DLT=156)"},
{ WTAP_ENCAP_USER10, "User 10 (DLT=157)"},
{ WTAP_ENCAP_USER11, "User 11 (DLT=158)"},
{ WTAP_ENCAP_USER12, "User 12 (DLT=159)"},
{ WTAP_ENCAP_USER13, "User 13 (DLT=160)"},
{ WTAP_ENCAP_USER14, "User 14 (DLT=161)"},
{ WTAP_ENCAP_USER15, "User 15 (DLT=162)"},
{ 0, NULL }
};
static int proto_user_encap = -1;
static expert_field ei_user_encap_not_handled = EI_INIT;
static user_encap_t* encaps = NULL;
static guint num_encaps = 0;
static uat_t* encaps_uat;
static gint exported_pdu_tap = -1;
static dissector_handle_t user_encap_handle;
/*
* Use this for DLT_USER2 if we don't have an encapsulation for it.
*/
static user_encap_t user2_encap = {WTAP_ENCAP_USER2, "pktap", NULL, "", NULL, "", NULL, 0, 0};
static void export_pdu(tvbuff_t *tvb, packet_info* pinfo, char *proto_name)
{
if (have_tap_listener(exported_pdu_tap)) {
static const exp_pdu_data_item_t *user_encap_exp_pdu_items[] = {
&exp_pdu_data_orig_frame_num,
NULL
};
exp_pdu_data_t *exp_pdu_data = export_pdu_create_tags(pinfo, proto_name, EXP_PDU_TAG_DISSECTOR_NAME, user_encap_exp_pdu_items);
exp_pdu_data->tvb_captured_length = tvb_captured_length(tvb);
exp_pdu_data->tvb_reported_length = tvb_reported_length(tvb);
exp_pdu_data->pdu_tvb = tvb;
tap_queue_packet(exported_pdu_tap, pinfo, exp_pdu_data);
}
}
static int dissect_user(tvbuff_t* tvb, packet_info* pinfo, proto_tree* tree, void* data _U_) {
user_encap_t* encap = NULL;
tvbuff_t* payload_tvb;
proto_item* item;
gint len, reported_len;
guint i;
for (i = 0; i < num_encaps; i++) {
if (encaps[i].encap == pinfo->match_uint) {
encap = &(encaps[i]);
break;
}
}
item = proto_tree_add_item(tree,proto_user_encap,tvb,0,-1,ENC_NA);
if (!encap && pinfo->match_uint == WTAP_ENCAP_USER2) {
/*
* Special-case DLT_USER2 - Apple hijacked it for use as DLT_PKTAP.
* The user hasn't assigned anything to it, so default it to
* the PKTAP dissector.
*/
encap = &user2_encap;
}
if (!encap) {
char* msg = wmem_strdup_printf(pinfo->pool,
"User encapsulation not handled: DLT=%d, "
"check your Preferences->Protocols->DLT_USER",
pinfo->match_uint + 147 - WTAP_ENCAP_USER0);
proto_item_set_text(item,"%s",msg);
expert_add_info_format(pinfo, item, &ei_user_encap_not_handled, "%s", msg);
call_data_dissector(tvb, pinfo, tree);
return tvb_captured_length(tvb);
}
if (encap->payload_proto == NULL) {
char* msg = wmem_strdup_printf(pinfo->pool,
"User encapsulation's protocol %s not found: "
"DLT=%d, check your Preferences->Protocols->DLT_USER",
encap->payload_proto_name,
pinfo->match_uint + 147 - WTAP_ENCAP_USER0);
proto_item_set_text(item,"%s",msg);
expert_add_info_format(pinfo, item, &ei_user_encap_not_handled, "%s", msg);
call_data_dissector(tvb, pinfo, tree);
return tvb_captured_length(tvb);
}
proto_item_set_text(item,"DLT: %d",pinfo->match_uint + 147 - WTAP_ENCAP_USER0);
if (encap->header_size) {
tvbuff_t* hdr_tvb = tvb_new_subset_length(tvb, 0, encap->header_size);
export_pdu(hdr_tvb, pinfo, encap->header_proto_name);
call_dissector(encap->header_proto, hdr_tvb, pinfo, tree);
if (encap->header_proto_name) {
const char *proto_name = dissector_handle_get_long_name(encap->header_proto);
if (proto_name) {
proto_item_append_text(item, ", Header: %s (%s)", encap->header_proto_name, proto_name);
}
}
}
len = tvb_captured_length(tvb) - (encap->header_size + encap->trailer_size);
reported_len = tvb_reported_length(tvb) - (encap->header_size + encap->trailer_size);
payload_tvb = tvb_new_subset_length_caplen(tvb, encap->header_size, len, reported_len);
export_pdu(payload_tvb, pinfo, encap->payload_proto_name);
call_dissector(encap->payload_proto, payload_tvb, pinfo, tree);
if (encap->payload_proto_name) {
const char *proto_name = dissector_handle_get_long_name(encap->payload_proto);
if (proto_name) {
proto_item_append_text(item, ", Payload: %s (%s)", encap->payload_proto_name, proto_name);
}
}
if (encap->trailer_size) {
tvbuff_t* trailer_tvb = tvb_new_subset_length(tvb, encap->header_size + len, encap->trailer_size);
export_pdu(trailer_tvb, pinfo, encap->trailer_proto_name);
call_dissector(encap->trailer_proto, trailer_tvb, pinfo, tree);
if (encap->trailer_proto_name) {
const char *proto_name = dissector_handle_get_long_name(encap->trailer_proto);
if (proto_name) {
proto_item_append_text(item, ", Trailer: %s (%s)", encap->trailer_proto_name, proto_name);
}
}
}
return tvb_captured_length(tvb);
}
static void* user_copy_cb(void* dest, const void* orig, size_t len _U_)
{
const user_encap_t *o = (const user_encap_t *)orig;
user_encap_t *d = (user_encap_t *)dest;
d->encap = o->encap;
d->payload_proto_name = g_strdup(o->payload_proto_name);
d->payload_proto = o->payload_proto;
d->header_proto_name = g_strdup(o->header_proto_name);
d->header_proto = o->header_proto;
d->trailer_proto_name = g_strdup(o->trailer_proto_name);
d->trailer_proto = o->trailer_proto;
d->header_size = o->header_size;
d->trailer_size = o->trailer_size;
return d;
}
static void user_free_cb(void* record)
{
user_encap_t *u = (user_encap_t *)record;
g_free(u->payload_proto_name);
g_free(u->header_proto_name);
g_free(u->trailer_proto_name);
}
UAT_VS_DEF(user_encap, encap, user_encap_t, guint, WTAP_ENCAP_USER0, ENCAP0_STR)
UAT_PROTO_DEF(user_encap, payload_proto, payload_proto, payload_proto_name, user_encap_t)
UAT_DEC_CB_DEF(user_encap, header_size, user_encap_t)
UAT_PROTO_DEF(user_encap, header_proto, header_proto, header_proto_name, user_encap_t)
UAT_DEC_CB_DEF(user_encap, trailer_size, user_encap_t)
UAT_PROTO_DEF(user_encap, trailer_proto, trailer_proto, trailer_proto_name, user_encap_t)
void proto_reg_handoff_user_encap(void)
{
guint i;
user2_encap.payload_proto = find_dissector("pktap");
for (i = WTAP_ENCAP_USER0; i <= WTAP_ENCAP_USER15; i++)
dissector_add_uint("wtap_encap", i, user_encap_handle);
}
void proto_register_user_encap(void)
{
module_t *module;
expert_module_t* expert_user_encap;
static uat_field_t user_flds[] = {
UAT_FLD_VS(user_encap,encap,"DLT",user_dlts,"The DLT"),
UAT_FLD_PROTO(user_encap,payload_proto,"Payload protocol",
"Protocol to be used for the payload of this DLT"),
UAT_FLD_DEC(user_encap,header_size,"Header size",
"Size of an eventual header that precedes the actual payload, 0 means none"),
UAT_FLD_PROTO(user_encap,header_proto,"Header protocol",
"Protocol to be used for the header (empty = data)"),
UAT_FLD_DEC(user_encap,trailer_size,"Trailer size",
"Size of an eventual trailer that follows the actual payload, 0 means none"),
UAT_FLD_PROTO(user_encap,trailer_proto,"Trailer protocol",
"Protocol to be used for the trailer (empty = data)"),
UAT_END_FIELDS
};
static ei_register_info ei[] = {
{ &ei_user_encap_not_handled, { "user_dlt.not_handled", PI_UNDECODED, PI_WARN, "Formatted text", EXPFILL }},
};
proto_user_encap = proto_register_protocol("DLT User","DLT_USER","user_dlt");
expert_user_encap = expert_register_protocol(proto_user_encap);
expert_register_field_array(expert_user_encap, ei, array_length(ei));
module = prefs_register_protocol(proto_user_encap, NULL);
encaps_uat = uat_new("User DLTs Table",
sizeof(user_encap_t),
"user_dlts",
TRUE,
&encaps,
&num_encaps,
UAT_AFFECTS_DISSECTION, /* affects dissection of packets, but not set of named fields */
"ChUserDLTsSection",
user_copy_cb,
NULL,
user_free_cb,
NULL,
NULL,
user_flds );
prefs_register_uat_preference(module,
"encaps_table",
"Encapsulations Table",
"A table that enumerates the various protocols to be used against a certain user DLT",
encaps_uat);
user_encap_handle = register_dissector("user_dlt",dissect_user,proto_user_encap);
/*
prefs_register_protocol_obsolete(proto_register_protocol("DLT User A","DLT_USER_A","user_dlt_a"));
prefs_register_protocol_obsolete(proto_register_protocol("DLT User B","DLT_USER_B","user_dlt_b"));
prefs_register_protocol_obsolete(proto_register_protocol("DLT User C","DLT_USER_C","user_dlt_c"));
prefs_register_protocol_obsolete(proto_register_protocol("DLT User D","DLT_USER_D","user_dlt_d"));
*/
exported_pdu_tap = register_export_pdu_tap("DLT User");
}
/*
* 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:
*/
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