epan/dissectors/packet-cisco-ttag.c

   1 /* packet-cisco-ttag.c
   2  * Routines for dissection of Cisco's ttag protocol.
   3  * Based on packet-cisco-metadata.c
   4  *
   5  * Copyright 2016 by Jaap Keuter (jkeuter[AT]xs4all.nl)
   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 #include <epan/etypes.h>
  18 #include <epan/to_str.h>
  19
  20 void proto_register_ttag(void);
  21 void proto_reg_handoff_ttag(void);
  22
  23 static dissector_handle_t ttag_handle;
  24
  25 static dissector_handle_t ethertype_handle;
  26
  27 static int proto_ttag;
  28
  29 static int hf_ttag_time_stamp;
  30 static int hf_ttag_eth_type;
  31
  32 static int ett_ttag;
  33
  34 static int
  35 dissect_ttag(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
  36 {
  37     uint64_t timestamp_value;
  38     nstime_t timestamp;
  39     uint16_t encap_proto;
  40     ethertype_data_t ethertype_data;
  41
  42     proto_tree *ttag_tree;
  43     proto_item *ti;
  44     int offset = 0;
  45
  46     col_set_str(pinfo->cinfo, COL_PROTOCOL, "TTAG");
  47     col_clear(pinfo->cinfo, COL_INFO);
  48
  49     ti = proto_tree_add_item(tree, proto_ttag, tvb, 0, 8, ENC_NA);
  50     ttag_tree = proto_item_add_subtree(ti, ett_ttag);
  51
  52     timestamp_value = tvb_get_uint48(tvb, offset, ENC_BIG_ENDIAN);
  53     timestamp.secs = (time_t) (timestamp_value / UINT64_C(1000000000));
  54     timestamp.nsecs = (uint32_t)(timestamp_value - (timestamp.secs * UINT64_C(1000000000)));
  55
  56     proto_item_append_text(ti, ", Timestamp: %s", rel_time_to_secs_str(pinfo->pool, &timestamp));
  57
  58     proto_tree_add_time(ttag_tree, hf_ttag_time_stamp, tvb, offset, 6, &timestamp);
  59     offset += 6;
  60
  61     encap_proto = tvb_get_ntohs(tvb, offset);
  62     proto_tree_add_uint(ttag_tree, hf_ttag_eth_type, tvb, offset, 2, encap_proto);
  63     offset += 2;
  64
  65     ethertype_data.etype = encap_proto;
  66     ethertype_data.payload_offset = offset;
  67     ethertype_data.fh_tree = ttag_tree;
  68     /* ttag doesn't define a trailer, but there's no way to tell Ethertype dissector that.
  69      * At least use the correct header field to reflect that and allow proper filter expression,
  70      * although it will still be attached to our tree instead of Ethernet II.
  71      */
  72     ethertype_data.trailer_id = proto_registrar_get_id_byname("eth.trailer");
  73     ethertype_data.fcs_len = 0;
  74
  75     call_dissector_with_data(ethertype_handle, tvb, pinfo, tree, &ethertype_data);
  76
  77     return tvb_captured_length(tvb);
  78 }
  79
  80 void
  81 proto_register_ttag(void)
  82 {
  83     static hf_register_info hf[] = {
  84         { &hf_ttag_time_stamp,
  85             { "Time stamp", "ttag.time_stamp", FT_RELATIVE_TIME, 0, NULL, 0x0, NULL, HFILL }
  86         },
  87         { &hf_ttag_eth_type,
  88             { "Type", "ttag.type", FT_UINT16, BASE_HEX, VALS(etype_vals), 0x0, NULL, HFILL }
  89         }
  90     };
  91
  92     static int *ett[] = {
  93         &ett_ttag
  94     };
  95
  96     proto_ttag = proto_register_protocol("Cisco ttag", "Cisco ttag", "ttag");
  97     proto_register_field_array(proto_ttag, hf, array_length(hf));
  98     proto_register_subtree_array(ett, array_length(ett));
  99
 100     ttag_handle = register_dissector("ttag", dissect_ttag, proto_ttag);
 101 }
 102
 103 void
 104 proto_reg_handoff_ttag(void)
 105 {
 106     ethertype_handle = find_dissector_add_dependency("ethertype", proto_ttag);
 107
 108     dissector_add_for_decode_as("ethertype", ttag_handle);
 109 }
 110
 111 /*
 112  * Editor modelines  -  https://www.wireshark.org/tools/modelines.html
 113  *
 114  * Local variables:
 115  * c-basic-offset: 4
 116  * tab-width: 8
 117  * indent-tabs-mode: nil
 118  * End:
 119  *
 120  * vi: set shiftwidth=4 tabstop=8 expandtab:
 121  * :indentSize=4:tabSize=8:noTabs=true:
 122  */