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/* packet-jmirror.c
* Routines for Jmirror protocol packet disassembly
* By Wayne Brassem <wbrassem@juniper.net>
* Copyright 2009 Wayne Brassem
* 2012 Wayne Brassem - Correction to support IPv6 over PPP
*
* Wireshark - Network traffic analyzer
* By Gerald Combs <gerald@wireshark.org>
* Copyright 1998 Gerald Combs
*
* SPDX-License-Identifier: GPL-2.0-or-later
*/
#include "config.h"
#include <epan/packet.h>
void proto_register_jmirror(void);
void proto_reg_handoff_jmirror(void);
static dissector_handle_t jmirror_handle;
#define MIRROR_HDR_SZ 8
#define MIRROR_ID_SZ 4
#define SESSION_ID_SZ 4
#define DEF_JMIRROR_UDP_PORT 30030 /* a product of primes (1*2*3*5*7*11*13) :-) Not IANA registered */
/*
* See www.juniper.net JUNOSe Packet Mirroring documentation
*/
/* Jmirror protocol variables */
static int proto_jmirror = -1;
static int hf_jmirror_mid = -1;
static int hf_jmirror_sid = -1;
static gint ett_jmirror = -1;
/* Handles which point to the packet dissectors */
static dissector_handle_t ipv4_handle;
static dissector_handle_t ipv6_handle;
static dissector_handle_t hdlc_handle;
/* Routine to return the dissector handle based on heuristic packet inspection */
static dissector_handle_t
get_heuristic_handle(tvbuff_t *tvb)
{
int offset = MIRROR_HDR_SZ; /* Point past the 8 byte mirror header */
int byte0, byte1, byte2, byte3;
/* The following section is designed to determine the nature of the mirrored packet.
*
* The first four bytes will be inspected to deduce the type of traffic.
* The bit pattern shown below is the basis. A bit of "x" is a variable field.
*
* IPv4 Header: 0100 0101 xxxx xx00 ==> Pattern for standard IPv4 20-byte header
* IPv6 Header: 0110 xxxx xxxx xxxx xxxx xxxx xxxx xxxx ==> Pattern for standard IPv6 header with variable TC and Flow
* PPP/HDLC: 1111 1111 0000 0011 xx00 0000 0010 0001 ==> HDLC-like framing for PPP (FF 03 x0 21)
* PPP/HDLC: 1111 1111 0000 0011 0000 0000 0101 0111 ==> HDLC-like framing for PPP IPv6 (FF 03 00 57)
*/
if (!tvb_bytes_exist(tvb, offset, 4))
return NULL; /* Not enough bytes for heuristic test */
/* Filter for IPv4 and IPv6 packets */
byte0 = tvb_get_guint8(tvb, offset + 0);
byte1 = tvb_get_guint8(tvb, offset + 1);
byte2 = tvb_get_guint8(tvb, offset + 2);
byte3 = tvb_get_guint8(tvb, offset + 3);
/* Look for IPv4 with standard header length */
if ( byte0 == 0x45 && ipv4_handle )
return ipv4_handle;
/* Look for IPv6 */
else if ( hi_nibble(byte0) == 6 && ipv6_handle )
return ipv6_handle;
/* Look for PPP/HDLC for LCP and IPv4 */
else if ( byte0 == 0xff && byte1 == 0x03 && lo_nibble(byte2) == 0 && byte3 == 0x21 && hdlc_handle )
return hdlc_handle;
/* Look for PPP/HDLC for IPv6 */
else if ( byte0 == 0xff && byte1 == 0x03 && byte2 == 0 && byte3 == 0x57 && hdlc_handle )
return hdlc_handle;
/* If it's something else entirely return nothing */
else
return NULL;
}
/* Heuristic UDP dissector called by Wireshark looking for embedded IPv4, IPv6 or L2TP/HDLC Jmirror packets */
static int
dissect_jmirror(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data _U_)
{
int offset = 0;
dissector_handle_t dissector_handle;
unsigned int midval, sidval;
proto_item *ti = NULL;
proto_tree *jmirror_tree = NULL;
tvbuff_t *next_tvb = NULL;
if ( !( dissector_handle = get_heuristic_handle(tvb) ) )
return 0;
/* Populate the Protocol field in the Wireshark packet display */
col_set_str(pinfo->cinfo, COL_PROTOCOL, "Jmirror");
/* Build the Jmirror Identifier value and store the string in a buffer */
midval = tvb_get_ntohl(tvb, offset);
/* Build the Session Identifier value and store the string in a buffer */
sidval = tvb_get_ntohl(tvb, offset+MIRROR_ID_SZ);
/* Populate the Info field in the Wireshark packet display */
col_add_fstr(pinfo->cinfo, COL_INFO, "MID: 0X%08x (%d), SID: 0x%08x (%d)", midval, midval, sidval, sidval);
/* Create a header for the Mirror Header in the protocol tree */
ti = proto_tree_add_protocol_format(tree, proto_jmirror, tvb, offset, MIRROR_HDR_SZ,
"Juniper Packet Mirror, MID: 0x%08x (%d), SID: 0x%08x (%d)", midval, midval, sidval, sidval);
/* Add the Juniper Packet Mirror to the main protocol tree */
jmirror_tree = proto_item_add_subtree(ti, ett_jmirror);
/* Insert the Jmirror Identifier into the protocol tree and assign value to filter variable */
proto_tree_add_item(jmirror_tree, hf_jmirror_mid, tvb, offset, MIRROR_ID_SZ, ENC_BIG_ENDIAN);
/* Push the tvbuff_t offset pointer along to the Session Identifier */
offset += MIRROR_ID_SZ;
/* Insert the Session Identifier into the protocol tree and assign value to filter variable */
proto_tree_add_item(jmirror_tree, hf_jmirror_sid, tvb, offset, SESSION_ID_SZ, ENC_BIG_ENDIAN);
/* Push the tvbuff_t offset pointer along to the start of the mirrored packet */
offset += SESSION_ID_SZ;
/* Create a buffer pointer for the next dissector */
next_tvb = tvb_new_subset_remaining(tvb, offset);
/* Call the next dissector based on the heuristics and return the number of bytes dissected */
return MIRROR_HDR_SZ + call_dissector(dissector_handle, next_tvb, pinfo, tree);
}
/* Register Jmirror dissector with Wireshark */
void
proto_register_jmirror(void)
{
/* Used by the Expression dialog and filter box */
static hf_register_info jmirror_hf[] = {
{ &hf_jmirror_mid,
{ "Jmirror Identifier", "jmirror.mid", FT_UINT32, BASE_HEX_DEC, NULL, 0x0,
"Unique identifier of the mirrored session", HFILL }
},
{ &hf_jmirror_sid,
{ "Session Identifier", "jmirror.sid", FT_UINT32, BASE_HEX_DEC, NULL, 0x0,
"Unique identifier of the user session", HFILL }
}
};
static gint *jmirror_ett[] = {
&ett_jmirror
};
/* Register the Jmirror protocol with Wireshark */
proto_jmirror = proto_register_protocol("Juniper Packet Mirror", "Jmirror", "jmirror");
/* Register the Jmirror subfields for filters */
proto_register_field_array(proto_jmirror, jmirror_hf, array_length(jmirror_hf));
proto_register_subtree_array(jmirror_ett, array_length(jmirror_ett));
/* Create a dissector handle for the Jmirror protocol */
jmirror_handle = register_dissector("jmirror", dissect_jmirror, proto_jmirror);
}
/* Create attachment point for dissector in Wireshark */
void
proto_reg_handoff_jmirror(void)
{
/* register as heuristic dissector for UDP */
/* heur_dissector_add("udp", dissect_jmirror, proto_jmirror); */
/* Create pointer to ipv4, ipv6, ppp and data dissectors */
ipv4_handle = find_dissector_add_dependency("ip", proto_jmirror);
ipv6_handle = find_dissector_add_dependency("ipv6", proto_jmirror);
hdlc_handle = find_dissector_add_dependency("pw_hdlc_nocw_hdlc_ppp", proto_jmirror);
/* Register as a normal IP dissector with default UDP port 30030 */
dissector_add_uint_with_preference("udp.port", DEF_JMIRROR_UDP_PORT, jmirror_handle);
}
/*
* 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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