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/* packet-redbackli.c
*
* Redback Lawful Intercept Packet dissector
*
* Copyright 2008 Florian Lohoff <flo[AT]rfc822.org>
*
* Wireshark - Network traffic analyzer
* By Gerald Combs <gerald[AT]wireshark.org>
* Copyright 1998 Gerald Combs
*
* SPDX-License-Identifier: GPL-2.0-or-later
*/
#include "config.h"
#include <epan/packet.h>
void proto_register_redbackli(void);
void proto_reg_handoff_redbackli(void);
static int proto_redbackli;
static int hf_redbackli_avptype;
static int hf_redbackli_avplen;
static int hf_redbackli_seqno; /* Sequence No */
static int hf_redbackli_liid; /* LI Id */
static int hf_redbackli_sessid; /* Session Id */
static int hf_redbackli_label; /* Label */
static int hf_redbackli_acctid; /* Accounting Session Id */
static int hf_redbackli_dir; /* Direction */
static int hf_redbackli_eohpad; /* End Of Header Padding */
static int hf_redbackli_unknownavp; /* Unknown AVP */
static int ett_redbackli;
static dissector_handle_t ip_handle;
static dissector_handle_t redbackli_handle;
#define RB_AVP_SEQNO 1
#define RB_AVP_LIID 2
#define RB_AVP_SESSID 3
#define RB_AVP_DIR 4
#define RB_AVP_LABEL 20
#define RB_AVP_ACCTID 40
#define RB_AVP_EOH 0
static const value_string avp_names[] = {
{RB_AVP_SEQNO, "Sequence No"},
{RB_AVP_LIID, "Lawful Intercept Id"},
{RB_AVP_SESSID, "Session Id"},
{RB_AVP_LABEL, "Label"},
{RB_AVP_ACCTID, "Accounting Session Id"},
{RB_AVP_DIR, "Direction"},
{RB_AVP_EOH, "End Of Header"},
{0, NULL}
};
static void
redbackli_dissect_avp(uint8_t avptype, uint8_t avplen, tvbuff_t *tvb, int offset, proto_tree *tree)
{
const char *avpname;
proto_tree *st = NULL;
avpname = val_to_str_const(avptype, avp_names, "Unknown");
st = proto_tree_add_subtree_format(tree, tvb, offset, avplen+2, ett_redbackli, NULL, "%s AVP", avpname);
proto_tree_add_uint(st, hf_redbackli_avptype, tvb, offset, 1, avptype);
proto_tree_add_uint(st, hf_redbackli_avplen, tvb, offset+1, 1, avplen);
if (!avplen)
return;
/* XXX: ToDo: Validate the length (avplen) of the fixed length fields
before calling proto_tree_add_item().
Note that the field lengths have been validated when
dissect_avp() is called from redbackli_dissect_heur().
*/
switch (avptype) {
case(RB_AVP_SEQNO):
proto_tree_add_item(st, hf_redbackli_seqno, tvb,
offset+2, avplen, ENC_BIG_ENDIAN);
break;
case(RB_AVP_LIID):
proto_tree_add_item(st, hf_redbackli_liid, tvb,
offset+2, avplen, ENC_BIG_ENDIAN);
break;
case(RB_AVP_SESSID):
proto_tree_add_item(st, hf_redbackli_sessid, tvb,
offset+2, avplen, ENC_BIG_ENDIAN);
break;
case(RB_AVP_LABEL):
proto_tree_add_item(st, hf_redbackli_label, tvb,
offset+2, avplen, ENC_ASCII);
break;
case(RB_AVP_EOH):
proto_tree_add_item(st, hf_redbackli_eohpad, tvb,
offset+2, avplen, ENC_NA);
break;
case(RB_AVP_DIR):
proto_tree_add_item(st, hf_redbackli_dir, tvb,
offset+2, avplen, ENC_NA);
break;
case(RB_AVP_ACCTID):
proto_tree_add_item(st, hf_redbackli_acctid, tvb,
offset+2, avplen, ENC_NA);
break;
default:
proto_tree_add_item(st, hf_redbackli_unknownavp, tvb,
offset+2, avplen, ENC_NA);
break;
}
return;
}
static int
redbackli_dissect(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
{
uint8_t avptype, avplen;
int len, offset = 0;
bool eoh;
proto_item *ti;
proto_tree *redbackli_tree = NULL;
tvbuff_t *next_tvb;
col_set_str(pinfo->cinfo, COL_PROTOCOL, "RBLI");
ti = proto_tree_add_item(tree, proto_redbackli,
tvb, 0, -1, ENC_NA);
redbackli_tree = proto_item_add_subtree(ti, ett_redbackli);
len = tvb_reported_length(tvb);
offset = 0;
eoh = false;
while (!eoh && (len > 2)) {
avptype = tvb_get_uint8(tvb, offset+0);
avplen = tvb_get_uint8(tvb, offset+1);
if ((len-2) < avplen) /* AVP Complete ? */
break;
if (tree)
redbackli_dissect_avp(avptype, avplen, tvb, offset, redbackli_tree);
if (avptype == RB_AVP_EOH)
eoh = true;
offset += 2 + avplen;
len -= 2 + avplen;
}
next_tvb = tvb_new_subset_remaining(tvb, offset);
call_dissector(ip_handle, next_tvb, pinfo, tree);
return tvb_captured_length(tvb);
}
#define REDBACKLI_INTSIZE 6
#define REDBACKLI_EOHSIZE 2
#define MIN_REDBACKLI_SIZE (3*REDBACKLI_INTSIZE+REDBACKLI_EOHSIZE)
static bool
redbackli_dissect_heur(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data)
{
int len, offset = 0;
bool eoh = false;
uint8_t avptype, avplen;
uint32_t avpfound = 0;
len = tvb_captured_length(tvb);
if (len < MIN_REDBACKLI_SIZE)
return false;
/*
* We scan the possible AVPs and look out for mismatches.
* An int AVP needs to be 4 byte long, and the eoh must be 0 or 1
* long .. Unknown AVPs also mean not for us ...
*
*/
while ((len > 2) && !eoh) {
avptype = tvb_get_uint8(tvb, offset+0);
avplen = tvb_get_uint8(tvb, offset+1);
switch (avptype) {
case(RB_AVP_SEQNO):
case(RB_AVP_LIID):
case(RB_AVP_SESSID):
if (avplen != 4)
return false;
avpfound |= 1<<avptype;
break;
case(RB_AVP_EOH):
if (avplen > 1 || offset == 0)
return false;
eoh = true;
break;
case(RB_AVP_LABEL):
case(RB_AVP_DIR): /* Is this correct? the hf_ originally had FT_UINT8 for DIR */
case(RB_AVP_ACCTID):
break;
default:
return false;
}
offset += 2 + avplen;
len -= 2 + avplen;
}
if (!(avpfound & (1<<RB_AVP_SEQNO)))
return false;
if (!(avpfound & (1<<RB_AVP_SESSID)))
return false;
if (!(avpfound & (1<<RB_AVP_LIID)))
return false;
redbackli_dissect(tvb, pinfo, tree, data);
return true;
}
void proto_register_redbackli(void) {
static hf_register_info hf[] = {
{ &hf_redbackli_avptype,
{ "AVP Type", "redbackli.avptype", FT_UINT8, BASE_DEC, NULL, 0x0,
NULL, HFILL }},
{ &hf_redbackli_avplen,
{ "AVP Length", "redbackli.avplen", FT_UINT8, BASE_DEC, NULL, 0x0,
NULL, HFILL }},
{ &hf_redbackli_seqno,
{ "Sequence No", "redbackli.seqno", FT_UINT32, BASE_DEC, NULL, 0x0,
NULL, HFILL }},
{ &hf_redbackli_liid,
{ "Lawful Intercept Id", "redbackli.liid", FT_UINT32, BASE_DEC, NULL, 0x0,
"LI Identifier", HFILL }},
{ &hf_redbackli_sessid,
{ "Session Id", "redbackli.sessid", FT_UINT32, BASE_DEC, NULL, 0x0,
"Session Identifier", HFILL }},
/* XXX: If one goes by the heuristic then this field can be variable length ??
* In the absence of any documentation We'll assume that's the case
* (even though 'direction' sounds like a fixed length field
*/
{ &hf_redbackli_dir,
{ "Direction", "redbackli.dir", FT_BYTES, BASE_NONE, NULL, 0x0,
NULL, HFILL }},
{ &hf_redbackli_label,
{ "Label", "redbackli.label", FT_STRING, BASE_NONE, NULL, 0x0,
NULL, HFILL }},
{ &hf_redbackli_acctid,
{ "Acctid", "redbackli.acctid", FT_BYTES, BASE_NONE, NULL, 0x0,
NULL, HFILL }},
{ &hf_redbackli_eohpad,
{ "End of Header Padding", "redbackli.eohpad", FT_BYTES, BASE_NONE, NULL, 0x0,
NULL, HFILL }},
{ &hf_redbackli_unknownavp,
{ "Unknown AVP", "redbackli.unknownavp", FT_BYTES, BASE_NONE, NULL, 0x0,
NULL, HFILL }}
};
static int *ett[] = {
&ett_redbackli
};
proto_redbackli = proto_register_protocol("Redback Lawful Intercept", "RedbackLI", "redbackli");
proto_register_field_array(proto_redbackli, hf, array_length(hf));
proto_register_subtree_array(ett, array_length(ett));
redbackli_handle = register_dissector("redbackli", redbackli_dissect, proto_redbackli);
}
void proto_reg_handoff_redbackli(void) {
ip_handle = find_dissector_add_dependency("ip", proto_redbackli);
dissector_add_for_decode_as_with_preference("udp.port", redbackli_handle);
heur_dissector_add("udp", redbackli_dissect_heur, "Redback Lawful Intercept over UDP", "redbackli_udp", proto_redbackli, HEURISTIC_ENABLE);
}
/*
* Editor modelines - https://www.wireshark.org/tools/modelines.html
*
* Local variables:
* c-basic-offset: 8
* tab-width: 8
* indent-tabs-mode: t
* End:
*
* vi: set shiftwidth=8 tabstop=8 noexpandtab:
* :indentSize=8:tabSize=8:noTabs=false:
*/
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