epan/dissectors/packet-jmirror.c

   1 /* packet-jmirror.c
   2  * Routines for Jmirror protocol packet disassembly
   3  * By Wayne Brassem <wbrassem@juniper.net>
   4  * Copyright 2009 Wayne Brassem
   5  *           2012 Wayne Brassem - Correction to support IPv6 over PPP
   6  *
   7  * $Id$
   8  *
   9  * Wireshark - Network traffic analyzer
  10  * By Gerald Combs <gerald@wireshark.org>
  11  * Copyright 1998 Gerald Combs
  12  *
  13  * This program is free software; you can redistribute it and/or
  14  * modify it under the terms of the GNU General Public License
  15  * as published by the Free Software Foundation; either version 2
  16  * of the License, or (at your option) any later version.
  17  *
  18  * This program is distributed in the hope that it will be useful,
  19  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  20  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  21  * GNU General Public License for more details.
  22  *
  23  * You should have received a copy of the GNU General Public License
  24  * along with this program; if not, write to the Free Software
  25  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  26  */
  27
  28 #include "config.h"
  29
  30 #include <epan/packet.h>
  31 #include <epan/prefs.h>
  32
  33 #define MIRROR_HDR_SZ           8
  34 #define MIRROR_ID_SZ            4
  35 #define SESSION_ID_SZ           4
  36 #define DEF_JMIRROR_UDP_PORT    30030 /* a product of primes (1*2*3*5*7*11*13)  :-) */
  37
  38 /*
  39  * See www.juniper.net JUNOSe Packet Mirroring documentation
  40  */
  41
  42 /* Jmirror protocol variables */
  43 static int proto_jmirror = -1;
  44 static int hf_jmirror_mid = -1;
  45 static int hf_jmirror_sid = -1;
  46 static gint ett_jmirror = -1;
  47
  48 /* Handles which point to the packet dissectors */
  49 static dissector_handle_t ipv4_handle;
  50 static dissector_handle_t ipv6_handle;
  51 static dissector_handle_t hdlc_handle;
  52
  53 static guint global_jmirror_udp_port = DEF_JMIRROR_UDP_PORT;
  54
  55 /* Forward declaration */
  56 void proto_reg_handoff_jmirror(void);
  57
  58 /* Routine to return the dissector handle based on heuristic packet inspection */
  59 static dissector_handle_t
  60 get_heuristic_handle(tvbuff_t *tvb)
  61 {
  62         int offset = MIRROR_HDR_SZ;            /* Point past the 8 byte mirror header */
  63         int byte0, byte1, byte2, byte3;
  64
  65         /* The following section is designed to determine the nature of the mirrored packet.
  66          *
  67          * The first four bytes will be inspected to deduce the type of traffic.
  68          * The bit pattern shown below is the basis.  A bit of "x" is a variable field.
  69          *
  70          * IPv4 Header: 0100 0101 xxxx xx00                     ==> Pattern for standard IPv4 20-byte header
  71          * IPv6 Header: 0110 xxxx xxxx 0000 0000 0000 0000 0000 ==> Pattern for standard IPv6 header with no flow label
  72          * PPP/HDLC:    1111 1111 0000 0011 xx00 0000 0010 0001 ==> HDLC-like framing for PPP (FF 03 x0 21)
  73          * PPP/HDLC:    1111 1111 0000 0011 0000 0000 0101 0111 ==> HDLC-like framing for PPP IPv6 (FF 03 00 57)
  74          */
  75
  76         if (!tvb_bytes_exist(tvb, offset, 4))
  77                 return NULL;   /* Not enough bytes for heuristic test */
  78
  79         /* Filter for IPv4 and IPv6 packets */
  80         byte0 = tvb_get_guint8(tvb, offset + 0);
  81         byte1 = tvb_get_guint8(tvb, offset + 1);
  82         byte2 = tvb_get_guint8(tvb, offset + 2);
  83         byte3 = tvb_get_guint8(tvb, offset + 3);
  84
  85         /* Look for IPv4 with standard header length */
  86         if ( byte0 == 0x45 && ipv4_handle )
  87                 return ipv4_handle;
  88
  89         /* Look for IPv6 with no flow label */
  90         else if ( hi_nibble(byte0) == 6 && lo_nibble(byte1) == 0 && byte2 == 0 && byte3 == 0 && ipv6_handle )
  91                 return ipv6_handle;
  92
  93         /* Look for PPP/HDLC for LCP and IPv4 */
  94         else if ( byte0 == 0xff && byte1 == 0x03 && lo_nibble(byte2) == 0 && byte3 == 0x21 && hdlc_handle )
  95                 return hdlc_handle;
  96
  97         /* Look for PPP/HDLC for IPv6 */
  98         else if ( byte0 == 0xff && byte1 == 0x03 && byte2 == 0 && byte3 == 0x57 && hdlc_handle )
  99                 return hdlc_handle;
 100
 101         /* If it's something else entirely return nothing */
 102         else
 103                 return NULL;
 104 }
 105
 106 /* Heuristic UDP dissector called by Wireshark looking for embedded IPv4, IPv6 or L2TP/HDLC Jmirror packets */
 107 static int
 108 dissect_jmirror(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data _U_)
 109 {
 110         int offset = 0;
 111         dissector_handle_t dissector_handle;
 112         unsigned int midval, sidval;
 113         proto_item *ti = NULL;
 114         proto_tree *jmirror_tree = NULL;
 115         tvbuff_t *next_tvb = NULL;
 116
 117         if ( !( dissector_handle = get_heuristic_handle(tvb) ) )
 118                 return 0;
 119
 120         /* Populate the Protocol field in the Wireshark packet display */
 121         col_set_str(pinfo->cinfo, COL_PROTOCOL, "Jmirror");
 122
 123         /* Build the Jmirror Identifier value and store the string in a buffer */
 124         midval = tvb_get_ntohl(tvb, offset);
 125
 126         /* Build the Session Identifier value and store the string in a buffer */
 127         sidval = tvb_get_ntohl(tvb, offset+MIRROR_ID_SZ);
 128
 129         /* Populate the Info field in the Wireshark packet display */
 130         col_add_fstr(pinfo->cinfo, COL_INFO, "MID: 0X%08x (%d), SID: 0x%08x (%d)", midval, midval, sidval, sidval);
 131
 132         /* Create a header for the Mirror Header in the protocol tree */
 133         ti = proto_tree_add_protocol_format(tree, proto_jmirror, tvb, offset, MIRROR_HDR_SZ,
 134                 "Juniper Packet Mirror, MID: 0x%08x (%d), SID: 0x%08x (%d)", midval, midval, sidval, sidval);
 135
 136         /* Add the Juniper Packet Mirror to the main protocol tree */
 137         jmirror_tree = proto_item_add_subtree(ti, ett_jmirror);
 138
 139         /* Insert the Jmirror Identifier into the protocol tree and assign value to filter variable */
 140         proto_tree_add_item(jmirror_tree, hf_jmirror_mid, tvb, offset, MIRROR_ID_SZ, ENC_BIG_ENDIAN);
 141
 142         /* Push the tvbuff_t offset pointer along to the Session Identifier */
 143         offset += MIRROR_ID_SZ;
 144
 145         /* Insert the Session Identifier into the protocol tree and assign value to filter variable */
 146         proto_tree_add_item(jmirror_tree, hf_jmirror_sid, tvb, offset, SESSION_ID_SZ, ENC_BIG_ENDIAN);
 147
 148         /* Push the tvbuff_t offset pointer along to the start of the mirrored packet */
 149         offset += SESSION_ID_SZ;
 150
 151         /* Create a buffer pointer for the next dissector */
 152         next_tvb = tvb_new_subset_remaining(tvb, offset);
 153
 154         /* Call the next dissector based on the heurstics and return the number of bytes dissected */
 155         return MIRROR_HDR_SZ + call_dissector(dissector_handle, next_tvb, pinfo, tree);
 156
 157 }
 158
 159 /* Register Jmirror dissector with Wireshark */
 160 void
 161 proto_register_jmirror(void)
 162 {
 163         module_t        *jmirror_module = NULL;
 164
 165         /* Used by the Expression dialog and filter box */
 166         static hf_register_info jmirror_hf[] = {
 167                 { &hf_jmirror_mid,
 168                   { "Jmirror Identifier", "jmirror.mid", FT_UINT32, BASE_HEX_DEC, NULL, 0x0,
 169                     "Unique identifier of the mirrored session", HFILL }
 170                 },
 171                 { &hf_jmirror_sid,
 172                   { "Session Identifier", "jmirror.sid", FT_UINT32, BASE_HEX_DEC, NULL, 0x0,
 173                     "Unique identifier of the user session", HFILL }
 174                 }
 175         };
 176         static gint *jmirror_ett[] = {
 177                 &ett_jmirror
 178         };
 179
 180         /* Register the Jmirror protocol with Wireshark */
 181         proto_jmirror = proto_register_protocol("Juniper Packet Mirror", "Jmirror", "jmirror");
 182
 183         /* Register the Jmirror preferences with Wireshark */
 184         jmirror_module = prefs_register_protocol(proto_jmirror, proto_reg_handoff_jmirror);
 185
 186         /* Allow the user to set the UDP port for the decode under the Edit -> Preferences menu */
 187         prefs_register_uint_preference(jmirror_module, "udp.port", "JMirror UDP Port",
 188                 "Set the port for JMirror Port (if other than the default of 30030)",
 189                 10, &global_jmirror_udp_port);
 190
 191         /* Register the Jmirror subfields for filters */
 192         proto_register_field_array(proto_jmirror, jmirror_hf, array_length(jmirror_hf));
 193         proto_register_subtree_array(jmirror_ett, array_length(jmirror_ett));
 194 }
 195
 196 /* Create attachment point for dissector in Wireshark */
 197 void
 198 proto_reg_handoff_jmirror(void)
 199 {
 200         static int jmirror_inited = FALSE;
 201         static guint jmirror_udp_port;
 202         static dissector_handle_t jmirror_handle;
 203
 204         if ( !jmirror_inited )
 205         {
 206                 /* register as heuristic dissector for UDP */
 207                 /* heur_dissector_add("udp", dissect_jmirror, proto_jmirror); */
 208
 209                 /* Create a dissector handle for the Jmirror protocol */
 210                 jmirror_handle = new_create_dissector_handle(dissect_jmirror, proto_jmirror);
 211
 212                 /* Create pointer to ipv4, ipv6, ppp and data dissectors */
 213                 ipv4_handle = find_dissector("ip");
 214                 ipv6_handle = find_dissector("ipv6");
 215                 hdlc_handle = find_dissector("pw_hdlc_nocw_hdlc_ppp");
 216
 217                 /* Set the init flag */
 218                 jmirror_inited = TRUE;
 219         } else {
 220                 /* Unregister from the old UDP port */
 221                 dissector_delete_uint("udp.port", jmirror_udp_port, jmirror_handle);
 222         }
 223
 224         jmirror_udp_port = global_jmirror_udp_port;
 225
 226         /* Register as a normal IP dissector with default UDP port 30030 */
 227         dissector_add_uint("udp.port", jmirror_udp_port, jmirror_handle);
 228 }