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  * Wireshark - Network traffic analyzer
   8  * By Gerald Combs <gerald@wireshark.org>
   9  * Copyright 1998 Gerald Combs
  10  *
  11  * SPDX-License-Identifier: GPL-2.0-or-later
  12  */
  13
  14 #include "config.h"
  15
  16 #include <epan/packet.h>
  17
  18 void proto_register_jmirror(void);
  19 void proto_reg_handoff_jmirror(void);
  20
  21 static dissector_handle_t jmirror_handle;
  22
  23 #define MIRROR_HDR_SZ           8
  24 #define MIRROR_ID_SZ            4
  25 #define SESSION_ID_SZ           4
  26 #define DEF_JMIRROR_UDP_PORT    30030 /* a product of primes (1*2*3*5*7*11*13)  :-) Not IANA registered */
  27
  28 /*
  29  * See www.juniper.net JUNOSe Packet Mirroring documentation
  30  */
  31
  32 /* Jmirror protocol variables */
  33 static int proto_jmirror;
  34 static int hf_jmirror_mid;
  35 static int hf_jmirror_sid;
  36 static int ett_jmirror;
  37
  38 /* Handles which point to the packet dissectors */
  39 static dissector_handle_t ipv4_handle;
  40 static dissector_handle_t ipv6_handle;
  41 static dissector_handle_t hdlc_handle;
  42
  43 /* Routine to return the dissector handle based on heuristic packet inspection */
  44 static dissector_handle_t
  45 get_heuristic_handle(tvbuff_t *tvb)
  46 {
  47         int offset = MIRROR_HDR_SZ;            /* Point past the 8 byte mirror header */
  48         int byte0, byte1, byte2, byte3;
  49
  50         /* The following section is designed to determine the nature of the mirrored packet.
  51          *
  52          * The first four bytes will be inspected to deduce the type of traffic.
  53          * The bit pattern shown below is the basis.  A bit of "x" is a variable field.
  54          *
  55          * IPv4 Header: 0100 0101 xxxx xx00                     ==> Pattern for standard IPv4 20-byte header
  56          * IPv6 Header: 0110 xxxx xxxx xxxx xxxx xxxx xxxx xxxx ==> Pattern for standard IPv6 header with variable TC and Flow
  57          * PPP/HDLC:    1111 1111 0000 0011 xx00 0000 0010 0001 ==> HDLC-like framing for PPP (FF 03 x0 21)
  58          * PPP/HDLC:    1111 1111 0000 0011 0000 0000 0101 0111 ==> HDLC-like framing for PPP IPv6 (FF 03 00 57)
  59          */
  60
  61         if (!tvb_bytes_exist(tvb, offset, 4))
  62                 return NULL;   /* Not enough bytes for heuristic test */
  63
  64         /* Filter for IPv4 and IPv6 packets */
  65         byte0 = tvb_get_uint8(tvb, offset + 0);
  66         byte1 = tvb_get_uint8(tvb, offset + 1);
  67         byte2 = tvb_get_uint8(tvb, offset + 2);
  68         byte3 = tvb_get_uint8(tvb, offset + 3);
  69
  70         /* Look for IPv4 with standard header length */
  71         if ( byte0 == 0x45 && ipv4_handle )
  72                 return ipv4_handle;
  73
  74         /* Look for IPv6 */
  75         else if ( hi_nibble(byte0) == 6 && ipv6_handle )
  76                 return ipv6_handle;
  77
  78         /* Look for PPP/HDLC for LCP and IPv4 */
  79         else if ( byte0 == 0xff && byte1 == 0x03 && lo_nibble(byte2) == 0 && byte3 == 0x21 && hdlc_handle )
  80                 return hdlc_handle;
  81
  82         /* Look for PPP/HDLC for IPv6 */
  83         else if ( byte0 == 0xff && byte1 == 0x03 && byte2 == 0 && byte3 == 0x57 && hdlc_handle )
  84                 return hdlc_handle;
  85
  86         /* If it's something else entirely return nothing */
  87         else
  88                 return NULL;
  89 }
  90
  91 /* Heuristic UDP dissector called by Wireshark looking for embedded IPv4, IPv6 or L2TP/HDLC Jmirror packets */
  92 static int
  93 dissect_jmirror(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data _U_)
  94 {
  95         int offset = 0;
  96         dissector_handle_t dissector_handle;
  97         unsigned int midval, sidval;
  98         proto_item *ti = NULL;
  99         proto_tree *jmirror_tree = NULL;
 100         tvbuff_t *next_tvb = NULL;
 101
 102         if ( !( dissector_handle = get_heuristic_handle(tvb) ) )
 103                 return 0;
 104
 105         /* Populate the Protocol field in the Wireshark packet display */
 106         col_set_str(pinfo->cinfo, COL_PROTOCOL, "Jmirror");
 107
 108         /* Build the Jmirror Identifier value and store the string in a buffer */
 109         midval = tvb_get_ntohl(tvb, offset);
 110
 111         /* Build the Session Identifier value and store the string in a buffer */
 112         sidval = tvb_get_ntohl(tvb, offset+MIRROR_ID_SZ);
 113
 114         /* Populate the Info field in the Wireshark packet display */
 115         col_add_fstr(pinfo->cinfo, COL_INFO, "MID: 0X%08x (%d), SID: 0x%08x (%d)", midval, midval, sidval, sidval);
 116
 117         /* Create a header for the Mirror Header in the protocol tree */
 118         ti = proto_tree_add_protocol_format(tree, proto_jmirror, tvb, offset, MIRROR_HDR_SZ,
 119                 "Juniper Packet Mirror, MID: 0x%08x (%d), SID: 0x%08x (%d)", midval, midval, sidval, sidval);
 120
 121         /* Add the Juniper Packet Mirror to the main protocol tree */
 122         jmirror_tree = proto_item_add_subtree(ti, ett_jmirror);
 123
 124         /* Insert the Jmirror Identifier into the protocol tree and assign value to filter variable */
 125         proto_tree_add_item(jmirror_tree, hf_jmirror_mid, tvb, offset, MIRROR_ID_SZ, ENC_BIG_ENDIAN);
 126
 127         /* Push the tvbuff_t offset pointer along to the Session Identifier */
 128         offset += MIRROR_ID_SZ;
 129
 130         /* Insert the Session Identifier into the protocol tree and assign value to filter variable */
 131         proto_tree_add_item(jmirror_tree, hf_jmirror_sid, tvb, offset, SESSION_ID_SZ, ENC_BIG_ENDIAN);
 132
 133         /* Push the tvbuff_t offset pointer along to the start of the mirrored packet */
 134         offset += SESSION_ID_SZ;
 135
 136         /* Create a buffer pointer for the next dissector */
 137         next_tvb = tvb_new_subset_remaining(tvb, offset);
 138
 139         /* Call the next dissector based on the heuristics and return the number of bytes dissected */
 140         return MIRROR_HDR_SZ + call_dissector(dissector_handle, next_tvb, pinfo, tree);
 141
 142 }
 143
 144 /* Register Jmirror dissector with Wireshark */
 145 void
 146 proto_register_jmirror(void)
 147 {
 148         /* Used by the Expression dialog and filter box */
 149         static hf_register_info jmirror_hf[] = {
 150                 { &hf_jmirror_mid,
 151                   { "Jmirror Identifier", "jmirror.mid", FT_UINT32, BASE_HEX_DEC, NULL, 0x0,
 152                     "Unique identifier of the mirrored session", HFILL }
 153                 },
 154                 { &hf_jmirror_sid,
 155                   { "Session Identifier", "jmirror.sid", FT_UINT32, BASE_HEX_DEC, NULL, 0x0,
 156                     "Unique identifier of the user session", HFILL }
 157                 }
 158         };
 159         static int *jmirror_ett[] = {
 160                 &ett_jmirror
 161         };
 162
 163         /* Register the Jmirror protocol with Wireshark */
 164         proto_jmirror = proto_register_protocol("Juniper Packet Mirror", "Jmirror", "jmirror");
 165
 166         /* Register the Jmirror subfields for filters */
 167         proto_register_field_array(proto_jmirror, jmirror_hf, array_length(jmirror_hf));
 168         proto_register_subtree_array(jmirror_ett, array_length(jmirror_ett));
 169
 170         /* Create a dissector handle for the Jmirror protocol */
 171         jmirror_handle = register_dissector("jmirror", dissect_jmirror, proto_jmirror);
 172
 173 }
 174
 175 /* Create attachment point for dissector in Wireshark */
 176 void
 177 proto_reg_handoff_jmirror(void)
 178 {
 179
 180         /* register as heuristic dissector for UDP */
 181         /* heur_dissector_add("udp", dissect_jmirror, proto_jmirror); */
 182
 183         /* Create pointer to ipv4, ipv6, ppp and data dissectors */
 184         ipv4_handle = find_dissector_add_dependency("ip", proto_jmirror);
 185         ipv6_handle = find_dissector_add_dependency("ipv6", proto_jmirror);
 186         hdlc_handle = find_dissector_add_dependency("pw_hdlc_nocw_hdlc_ppp", proto_jmirror);
 187
 188         /* Register as a normal IP dissector with default UDP port 30030 */
 189         dissector_add_uint_with_preference("udp.port", DEF_JMIRROR_UDP_PORT, jmirror_handle);
 190 }
 191
 192 /*
 193  * Editor modelines  -  https://www.wireshark.org/tools/modelines.html
 194  *
 195  * Local variables:
 196  * c-basic-offset: 8
 197  * tab-width: 8
 198  * indent-tabs-mode: t
 199  * End:
 200  *
 201  * vi: set shiftwidth=8 tabstop=8 noexpandtab:
 202  * :indentSize=8:tabSize=8:noTabs=false:
 203  */