epan/dissectors/packet-cisco-metadata.c

   1 /* packet-cisco-metadata.c
   2  * Routines for dissection of Cisco's MetaData protocol.
   3  * draft-smith-kandula-sxp
   4  * Copyright 2013 by Vaibhav Katkade (vkatkade[AT]cisco.com)
   5  *
   6  * Wireshark - Network traffic analyzer
   7  * By Gerald Combs <gerald@wireshark.org>
   8  * Copyright 1998 Gerald Combs
   9  *
  10  * SPDX-License-Identifier: GPL-2.0-or-later
  11  */
  12
  13 #include "config.h"
  14
  15 #include <epan/packet.h>
  16 #include <epan/etypes.h>
  17 #if 0
  18 #include "packet-ieee8023.h"
  19 #endif
  20
  21 void proto_register_cmd(void);
  22 void proto_reg_handoff_cmd(void);
  23
  24 static dissector_handle_t cmd_eth_handle;
  25 static dissector_handle_t cmd_gre_handle;
  26
  27 static dissector_handle_t ethertype_handle;
  28
  29 static dissector_table_t gre_dissector_table;
  30
  31 static int proto_cmd;
  32
  33 static int hf_cmd_version;
  34 static int hf_cmd_length;
  35 static int hf_cmd_options;
  36 static int hf_cmd_sgt;
  37
  38 static int hf_eth_type;
  39 static int hf_cmd_trailer;
  40
  41 static int ett_cmd;
  42
  43 static int
  44 dissect_cmd_eth(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
  45 {
  46     uint16_t encap_proto;
  47     ethertype_data_t ethertype_data;
  48
  49     proto_tree *cmd_tree = NULL;
  50     int offset = 0;
  51
  52     col_set_str(pinfo->cinfo, COL_PROTOCOL, "CMD");
  53     col_clear(pinfo->cinfo, COL_INFO);
  54
  55     if (tree) {
  56         proto_item *ti = proto_tree_add_item(tree, proto_cmd, tvb, 0, 8, ENC_NA);
  57
  58         cmd_tree = proto_item_add_subtree(ti, ett_cmd);
  59         proto_tree_add_item(cmd_tree, hf_cmd_version, tvb, offset, 1, ENC_BIG_ENDIAN);
  60         offset += 1;
  61         proto_tree_add_item(cmd_tree, hf_cmd_length, tvb, offset, 1, ENC_BIG_ENDIAN);
  62         offset += 1;
  63         proto_tree_add_item(cmd_tree, hf_cmd_options, tvb, offset, 2, ENC_BIG_ENDIAN);
  64         offset += 2;
  65         proto_tree_add_item(cmd_tree, hf_cmd_sgt, tvb, offset, 2, ENC_BIG_ENDIAN);
  66         /*offset += 2;*/
  67     }
  68
  69     encap_proto = tvb_get_ntohs(tvb, 6);
  70
  71 /* This Logic to identify and decode IEEE 802.3 frames is not working correctly. Carry over code from packet-vlan.c
  72  * Commenting it out for now will display as Unknown for L2 control frames instead of showing a wrong decode.
  73  */
  74 #if 0
  75     if (encap_proto <= IEEE_802_3_MAX_LEN) {
  76         bool is_802_2 = true;
  77
  78         /* Don't throw an exception for this check (even a BoundsError) */
  79         if (tvb_captured_length_remaining(tvb, 4) >= 2) {
  80             if (tvb_get_ntohs(tvb, 4) == 0xffff)
  81                 is_802_2 = false;
  82         }
  83
  84         dissect_802_3(encap_proto, is_802_2, tvb, 4, pinfo, tree, cmd_tree, hf_eth_type, hf_cmd_trailer, 0);
  85     } else {
  86 #endif
  87
  88     proto_tree_add_uint(cmd_tree, hf_eth_type, tvb, 6, 2, encap_proto);
  89
  90     ethertype_data.etype = encap_proto;
  91     ethertype_data.payload_offset = 8;
  92     ethertype_data.fh_tree = cmd_tree;
  93     ethertype_data.trailer_id = hf_cmd_trailer;
  94     ethertype_data.fcs_len = 0;
  95
  96     call_dissector_with_data(ethertype_handle, tvb, pinfo, tree, &ethertype_data);
  97     return tvb_captured_length(tvb);
  98 }
  99
 100 static int
 101 dissect_cmd_gre(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
 102 {
 103     proto_item *ti = NULL;
 104     proto_tree *cmd_tree = NULL;
 105     uint16_t encap_proto;
 106     tvbuff_t *next_tvb;
 107     int offset = 0;
 108
 109     col_set_str(pinfo->cinfo, COL_PROTOCOL, "CMD");
 110     col_clear(pinfo->cinfo, COL_INFO);
 111
 112     if (tree) {
 113         ti = proto_tree_add_item(tree, proto_cmd, tvb, 0, 6, ENC_NA);
 114         cmd_tree = proto_item_add_subtree(ti, ett_cmd);
 115     }
 116     encap_proto = tvb_get_ntohs(tvb, 0);
 117     proto_tree_add_item(cmd_tree, hf_eth_type, tvb, offset, 2, ENC_BIG_ENDIAN);
 118     offset += 2;
 119
 120     proto_tree_add_item(cmd_tree, hf_cmd_version, tvb, offset, 1, ENC_BIG_ENDIAN);
 121     offset += 1;
 122     proto_tree_add_item(cmd_tree, hf_cmd_length, tvb, offset, 1, ENC_BIG_ENDIAN);
 123     offset += 1;
 124     proto_tree_add_item(cmd_tree, hf_cmd_options, tvb, offset, 2, ENC_BIG_ENDIAN);
 125     offset += 2;
 126     proto_tree_add_item(cmd_tree, hf_cmd_sgt, tvb, offset, 2, ENC_BIG_ENDIAN);
 127     offset += 2;
 128
 129     next_tvb = tvb_new_subset_remaining(tvb, offset);
 130     if (!dissector_try_uint(gre_dissector_table, encap_proto, next_tvb, pinfo, tree))
 131         call_data_dissector(next_tvb, pinfo, tree);
 132     return tvb_captured_length(tvb);
 133 }
 134
 135 void
 136 proto_register_cmd(void)
 137 {
 138     static hf_register_info hf[] = {
 139         { &hf_cmd_version,
 140             { "Version", "cmd.version", FT_UINT8, BASE_DEC, NULL, 0x0, NULL, HFILL }
 141         },
 142         { &hf_cmd_length,
 143             { "Length", "cmd.length", FT_UINT8, BASE_DEC, NULL, 0x0, NULL, HFILL }
 144         },
 145         { &hf_cmd_options,
 146             { "Options", "cmd.options", FT_UINT16, BASE_HEX, NULL, 0x0, NULL, HFILL }
 147         },
 148         { &hf_cmd_sgt,
 149             { "SGT", "cmd.sgt", FT_UINT16, BASE_DEC, NULL, 0x0, NULL, HFILL }
 150         },
 151         { &hf_eth_type,
 152             { "Type", "cmd.type", FT_UINT16, BASE_HEX, VALS(etype_vals), 0x0, NULL, HFILL }
 153         },
 154         { &hf_cmd_trailer,
 155             { "Trailer", "cmd.trailer", FT_BYTES, BASE_NONE, NULL, 0x0, NULL, HFILL }
 156         },
 157     };
 158
 159     static int *ett[] = {
 160         &ett_cmd
 161     };
 162
 163     proto_cmd = proto_register_protocol("Cisco MetaData", "Cisco MetaData", "cmd");
 164     proto_register_field_array(proto_cmd, hf, array_length(hf));
 165     proto_register_subtree_array(ett, array_length(ett));
 166
 167     cmd_eth_handle = register_dissector("cmd.eth", dissect_cmd_eth, proto_cmd);
 168     cmd_gre_handle = register_dissector("cmd.gre", dissect_cmd_gre, proto_cmd);
 169 }
 170
 171 void
 172 proto_reg_handoff_cmd(void)
 173 {
 174     ethertype_handle = find_dissector_add_dependency("ethertype", proto_cmd);
 175
 176     gre_dissector_table = find_dissector_table("gre.proto");
 177
 178     dissector_add_uint("ethertype", ETHERTYPE_CMD, cmd_eth_handle);
 179     dissector_add_uint("gre.proto", ETHERTYPE_CMD, cmd_gre_handle);
 180 }
 181
 182 /*
 183  * Editor modelines  -  https://www.wireshark.org/tools/modelines.html
 184  *
 185  * Local variables:
 186  * c-basic-offset: 4
 187  * tab-width: 8
 188  * indent-tabs-mode: nil
 189  * End:
 190  *
 191  * vi: set shiftwidth=4 tabstop=8 expandtab:
 192  * :indentSize=4:tabSize=8:noTabs=true:
 193  */