epan/dissectors/packet-qllc.c

   1 /* packet-qllc.c
   2  * Routines for QLLC protocol - Qualified? LLC
   3  * Gilbert Ramirez <gram@alumni.rice.edu>
   4  *
   5  * Wireshark - Network traffic analyzer
   6  * By Gerald Combs <gerald@wireshark.org>
   7  * Copyright 2001 Gerald Combs
   8  *
   9  * SPDX-License-Identifier: GPL-2.0-or-later
  10  */
  11
  12 #include "config.h"
  13
  14 #include <epan/packet.h>
  15
  16 void proto_register_qllc(void);
  17 void proto_reg_handoff_qllc(void);
  18
  19 static int proto_qllc;
  20 static int hf_qllc_address;
  21 static int hf_qllc_control;
  22
  23 static int ett_qllc;
  24
  25 static dissector_handle_t sna_handle;
  26
  27 #define QSM                 0x93
  28 #define QDISC               0x53
  29 #define QXID                0xbf
  30 #define QTEST               0xf3
  31 #define QRR                 0xf1
  32 #define QRD                 0x53
  33 #define QUA                 0x73
  34 #define QDM                 0x1f
  35 #define QFRMR               0x97
  36 #define QUI                 0x03
  37 #define QUI_NO_REPLY        0x13
  38 #define QSIM                0x17
  39
  40 #define QRD_QDISC_VALUE     0x53
  41 #define QDISC_TEXT          "QDISC"
  42 #define QRD_TEXT            "QRD"
  43
  44 /* Control Field */
  45 static const value_string qllc_control_vals[] = {
  46     { QUI,          "QUI" },
  47     { QUI_NO_REPLY, "QUI - reply required" },
  48     { QSIM,         "QSIM" },
  49     { QDM,          "QDM" },
  50     { QUA,          "QUA" },
  51     { QSM,          "QSM" },
  52     { QFRMR,        "QFRMR" },
  53     { QXID,         "QXID" },
  54     { QRR,          "QRR" },
  55     { QTEST,        "QTEST" },
  56     { QDISC,        "QDISC / QRD" }, /* Same value for QDISC and QRD (following it is a COMMAND or RESPONSE) */
  57     { 0x00, NULL },
  58 };
  59
  60
  61 static int
  62 dissect_qllc(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data)
  63 {
  64     proto_tree *qllc_tree;
  65     proto_item *qllc_ti;
  66     bool       *q_bit_set;
  67     uint8_t     addr, ctrl;
  68     bool        command = false;
  69
  70     /* Reject the packet if data is NULL */
  71     if (data == NULL)
  72         return 0;
  73     q_bit_set = (bool *)data;
  74
  75     /*
  76      * If the Q bit isn't set, this is just SNA data.
  77      */
  78     if (!(*q_bit_set)) {
  79         call_dissector(sna_handle, tvb, pinfo, tree);
  80         return tvb_captured_length(tvb);
  81     }
  82
  83     /* Summary information */
  84     col_set_str(pinfo->cinfo, COL_PROTOCOL, "QLLC");
  85     col_clear(pinfo->cinfo, COL_INFO);
  86
  87     qllc_ti = proto_tree_add_item(tree, proto_qllc, tvb, 0, -1, ENC_NA);
  88     qllc_tree = proto_item_add_subtree(qllc_ti, ett_qllc);
  89
  90     /* Get the address; we need it to determine if this is a
  91      * COMMAND or a RESPONSE */
  92     addr = tvb_get_uint8(tvb, 0);
  93     proto_tree_add_item(qllc_tree, hf_qllc_address, tvb, 0, 1, ENC_BIG_ENDIAN);
  94
  95     /* The address field equals X'FF' in commands (except QRR)
  96      * and anything in responses. */
  97     ctrl = tvb_get_uint8(tvb, 1);
  98     if (ctrl != QRR && addr == 0xff) {
  99         command = true;
 100     }
 101
 102
 103     /* Disambiguate QRD_QDISC_VALUE, based on whether this packet is
 104      * a COMMAND or RESPONSE. */
 105     if (ctrl == QRD_QDISC_VALUE) {
 106         if (command) {
 107             col_set_str(pinfo->cinfo, COL_INFO, QDISC_TEXT);
 108             proto_tree_add_uint_format_value(qllc_tree, hf_qllc_control, tvb,
 109                     1, 1, ctrl, "%s (0x%02x)", QDISC_TEXT, ctrl);
 110         }
 111         else {
 112             col_set_str(pinfo->cinfo, COL_INFO, QRD_TEXT);
 113             proto_tree_add_uint_format_value(qllc_tree, hf_qllc_control, tvb,
 114                     1, 1, ctrl, "%s (0x%02x)", QRD_TEXT, ctrl);
 115         }
 116     }
 117     else {
 118         /* Non-ambiguous control field value */
 119         col_add_str(pinfo->cinfo, COL_INFO,
 120                     val_to_str(ctrl, qllc_control_vals,
 121                         "Control Field: 0x%02x (unknown)"));
 122
 123         proto_tree_add_uint(qllc_tree, hf_qllc_control, tvb,
 124                     1, 1, ctrl);
 125     }
 126
 127     /* Do we have an I field ? */
 128     /* XXX - I field exists for QUI too, but only for subarea nodes.
 129      * Need to test for this. */
 130     if (ctrl == QXID || ctrl == QTEST || ctrl == QFRMR) {
 131         /* yes */
 132     }
 133
 134     return tvb_captured_length(tvb);
 135 }
 136
 137 void
 138 proto_register_qllc(void)
 139 {
 140     static hf_register_info hf[] = {
 141         { &hf_qllc_address,
 142           { "Address Field", "qllc.address", FT_UINT8, BASE_HEX, NULL, 0x0,
 143             NULL, HFILL }},
 144
 145         { &hf_qllc_control,
 146           { "Control Field", "qllc.control", FT_UINT8, BASE_HEX,
 147             VALS(qllc_control_vals), 0x0, NULL, HFILL }},
 148     };
 149
 150     static int *ett[] = {
 151         &ett_qllc,
 152     };
 153
 154     proto_qllc = proto_register_protocol("Qualified Logical Link Control", "QLLC", "qllc");
 155     proto_register_field_array(proto_qllc, hf, array_length(hf));
 156     proto_register_subtree_array(ett, array_length(ett));
 157     register_dissector("qllc", dissect_qllc, proto_qllc);
 158 }
 159
 160 void
 161 proto_reg_handoff_qllc(void)
 162 {
 163     sna_handle = find_dissector_add_dependency("sna", proto_qllc);
 164 }
 165
 166 /*
 167  * Editor modelines  -  https://www.wireshark.org/tools/modelines.html
 168  *
 169  * Local variables:
 170  * c-basic-offset: 4
 171  * tab-width: 8
 172  * indent-tabs-mode: nil
 173  * End:
 174  *
 175  * vi: set shiftwidth=4 tabstop=8 expandtab:
 176  * :indentSize=4:tabSize=8:noTabs=true:
 177  */