epan/dissectors/packet-x75.c

   1 /* packet-x75.c
   2  * Routines for X.75 frame disassembly
   3  * Manawyrm <git@tbspace.de>
   4  *
   5  * based on lapb dissector by
   6  * Olivier Abad <oabad@noos.fr>
   7  *
   8  * Wireshark - Network traffic analyzer
   9  * By Gerald Combs <gerald@wireshark.org>
  10  * Copyright 1998
  11  *
  12  * SPDX-License-Identifier: GPL-2.0-or-later
  13  */
  14
  15 #include "config.h"
  16
  17 #include <epan/decode_as.h>
  18 #include <epan/packet.h>
  19 #include <epan/tfs.h>
  20 #include <wsutil/array.h>
  21 #include <epan/xdlc.h>
  22
  23 static dissector_table_t x75_subdissector_table;
  24
  25 void proto_register_x75(void);
  26 void proto_reg_handoff_x75(void);
  27
  28 #define X75_ADDRESS_SLP_STE_A 0x03
  29 #define X75_ADDRESS_SLP_STE_B 0x01
  30 #define X75_ADDRESS_MLP_STE_C 0x0F
  31 #define X75_ADDRESS_MLP_STE_D 0x07
  32
  33 static int proto_x75;
  34 static int hf_x75_address;
  35 static int hf_x75_control;
  36 static int hf_x75_n_r;
  37 static int hf_x75_n_s;
  38 static int hf_x75_p;
  39 static int hf_x75_f;
  40 static int hf_x75_s_ftype;
  41 static int hf_x75_u_modifier_cmd;
  42 static int hf_x75_u_modifier_resp;
  43 static int hf_x75_ftype_i;
  44 static int hf_x75_ftype_s_u;
  45
  46 static int ett_x75;
  47 static int ett_x75_control;
  48
  49 static dissector_handle_t data_handle;
  50 static dissector_handle_t x75_handle;
  51
  52 static const xdlc_cf_items x75_cf_items = {
  53     &hf_x75_n_r,
  54     &hf_x75_n_s,
  55     &hf_x75_p,
  56     &hf_x75_f,
  57     &hf_x75_s_ftype,
  58     &hf_x75_u_modifier_cmd,
  59     &hf_x75_u_modifier_resp,
  60     &hf_x75_ftype_i,
  61     &hf_x75_ftype_s_u
  62 };
  63
  64 static int
  65 dissect_x75(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
  66 {
  67     proto_tree          *x75_tree, *ti;
  68     uint16_t            control;
  69     int                 is_response;
  70     uint8_t             byte0;
  71     tvbuff_t            *next_tvb;
  72
  73     col_set_str(pinfo->cinfo, COL_PROTOCOL, "X.75");
  74     col_set_str(pinfo->cinfo, COL_RES_NET_DST, "Broadcast");
  75
  76     byte0 = tvb_get_uint8(tvb, 0);
  77
  78     if (byte0 != X75_ADDRESS_SLP_STE_A && byte0 != X75_ADDRESS_SLP_STE_B &&
  79         byte0 != X75_ADDRESS_MLP_STE_C && byte0 != X75_ADDRESS_MLP_STE_D) /* invalid X.75 frame */
  80     {
  81         col_set_str(pinfo->cinfo, COL_INFO, "Invalid X.75 frame");
  82         if (tree)
  83             proto_tree_add_protocol_format(tree, proto_x75, tvb, 0, -1,
  84                             "Invalid X.75 frame");
  85         return 1;
  86     }
  87
  88     // Clear lower layer src/dst address types, so our custom names
  89     // are shown in the Packet List pane
  90     pinfo->src.type = AT_NONE;
  91     pinfo->dst.type = AT_NONE;
  92
  93     switch (pinfo->p2p_dir) {
  94     case P2P_DIR_SENT:
  95         if (byte0 == X75_ADDRESS_SLP_STE_A || byte0 == X75_ADDRESS_SLP_STE_B)
  96         {
  97             col_set_str(pinfo->cinfo, COL_RES_DL_SRC, "STE A");
  98             col_set_str(pinfo->cinfo, COL_RES_DL_DST, "STE B");
  99         }
 100         else
 101         {
 102             col_set_str(pinfo->cinfo, COL_RES_DL_SRC, "STE C");
 103             col_set_str(pinfo->cinfo, COL_RES_DL_DST, "STE D");
 104         }
 105
 106         if (byte0 == X75_ADDRESS_SLP_STE_A || byte0 == X75_ADDRESS_MLP_STE_C)
 107             is_response = true;
 108         else
 109             is_response = false;
 110         break;
 111
 112     case P2P_DIR_RECV:
 113         if (byte0 == X75_ADDRESS_SLP_STE_A || byte0 == X75_ADDRESS_SLP_STE_B)
 114         {
 115             col_set_str(pinfo->cinfo, COL_RES_DL_SRC, "STE B");
 116             col_set_str(pinfo->cinfo, COL_RES_DL_DST, "STE A");
 117         }
 118         else
 119         {
 120             col_set_str(pinfo->cinfo, COL_RES_DL_SRC, "STE D");
 121             col_set_str(pinfo->cinfo, COL_RES_DL_DST, "STE C");
 122         }
 123
 124         if (byte0 == X75_ADDRESS_SLP_STE_B || byte0 == X75_ADDRESS_MLP_STE_D)
 125             is_response = true;
 126         else
 127             is_response = false;
 128         break;
 129
 130     default:
 131         is_response = false;
 132         break;
 133     }
 134
 135     if (is_response)
 136     {
 137         col_set_str(pinfo->cinfo, COL_PROTOCOL, "X.75 RSP");
 138     }
 139     else
 140     {
 141         col_set_str(pinfo->cinfo, COL_PROTOCOL, "X.75 CMD");
 142     }
 143
 144     ti = proto_tree_add_protocol_format(tree, proto_x75, tvb, 0, 2,
 145                                         "X.75");
 146     x75_tree = proto_item_add_subtree(ti, ett_x75);
 147     proto_tree_add_uint(x75_tree, hf_x75_address, tvb, 0, 1, byte0);
 148
 149     control = dissect_xdlc_control(tvb, 1, pinfo, x75_tree, hf_x75_control,
 150             ett_x75_control, &x75_cf_items, NULL, NULL, NULL,
 151             is_response, false, false);
 152
 153     /* information frame ==> data */
 154     if (XDLC_IS_INFORMATION(control)) {
 155         next_tvb = tvb_new_subset_remaining(tvb, 2);
 156
 157         int len = tvb_reported_length_remaining(next_tvb, 0);
 158
 159         // limit number of bytes being shown in COL_INFO
 160         if (len > 128)
 161             len = 128;
 162
 163         col_append_fstr(pinfo->cinfo, COL_INFO, ", %s", tvb_format_text(pinfo->pool, next_tvb, 0, len));
 164
 165         if (!dissector_try_payload_with_data(x75_subdissector_table, next_tvb, pinfo, tree, true, NULL)) {
 166             call_dissector(data_handle, next_tvb, pinfo, tree);
 167         }
 168     }
 169     return tvb_captured_length(tvb);
 170 }
 171
 172 void
 173 proto_register_x75(void)
 174 {
 175     static hf_register_info hf[] = {
 176         { &hf_x75_address,
 177           { "Address", "x75.address", FT_UINT8, BASE_HEX, NULL, 0x0,
 178             NULL, HFILL }},
 179
 180         { &hf_x75_control,
 181           { "Control Field", "x75.control", FT_UINT8, BASE_HEX, NULL, 0x0,
 182             NULL, HFILL }},
 183
 184         { &hf_x75_n_r,
 185           { "N(R)", "x75.control.n_r", FT_UINT8, BASE_DEC,
 186             NULL, XDLC_N_R_MASK, NULL, HFILL }},
 187
 188         { &hf_x75_n_s,
 189           { "N(S)", "x75.control.n_s", FT_UINT8, BASE_DEC,
 190             NULL, XDLC_N_S_MASK, NULL, HFILL }},
 191
 192         { &hf_x75_p,
 193           { "Poll", "x75.control.p", FT_BOOLEAN, 8,
 194             TFS(&tfs_set_notset), XDLC_P_F, NULL, HFILL }},
 195
 196         { &hf_x75_f,
 197           { "Final", "x75.control.f", FT_BOOLEAN, 8,
 198             TFS(&tfs_set_notset), XDLC_P_F, NULL, HFILL }},
 199
 200         { &hf_x75_s_ftype,
 201           { "Supervisory frame type", "x75.control.s_ftype", FT_UINT8, BASE_HEX,
 202             VALS(stype_vals), XDLC_S_FTYPE_MASK, NULL, HFILL }},
 203
 204         { &hf_x75_u_modifier_cmd,
 205           { "Command", "x75.control.u_modifier_cmd", FT_UINT8, BASE_HEX,
 206             VALS(modifier_vals_cmd), XDLC_U_MODIFIER_MASK, NULL, HFILL }},
 207
 208         { &hf_x75_u_modifier_resp,
 209           { "Response", "x75.control.u_modifier_resp", FT_UINT8, BASE_HEX,
 210             VALS(modifier_vals_resp), XDLC_U_MODIFIER_MASK, NULL, HFILL }},
 211
 212         { &hf_x75_ftype_i,
 213           { "Frame type", "x75.control.ftype", FT_UINT8, BASE_HEX,
 214             VALS(ftype_vals), XDLC_I_MASK, NULL, HFILL }},
 215
 216         { &hf_x75_ftype_s_u,
 217           { "Frame type", "x75.control.ftype", FT_UINT8, BASE_HEX,
 218             VALS(ftype_vals), XDLC_S_U_MASK, NULL, HFILL }},
 219     };
 220     static int *ett[] = {
 221         &ett_x75,
 222         &ett_x75_control,
 223     };
 224
 225     proto_x75 = proto_register_protocol("Async data over ISDN (X.75)",
 226                                          "X.75", "x75");
 227     proto_register_field_array (proto_x75, hf, array_length(hf));
 228     proto_register_subtree_array(ett, array_length(ett));
 229
 230     x75_handle = register_dissector("x75", dissect_x75, proto_x75);
 231
 232     x75_subdissector_table =
 233             register_decode_as_next_proto(proto_x75,
 234                           "x75.subdissector", "X.75 payload subdissector", NULL);
 235 }
 236
 237 void
 238 proto_reg_handoff_x75(void)
 239 {
 240     data_handle = find_dissector("data");
 241 }
 242
 243 /*
 244  * Editor modelines  -  https://www.wireshark.org/tools/modelines.html
 245  *
 246  * Local variables:
 247  * c-basic-offset: 4
 248  * tab-width: 8
 249  * indent-tabs-mode: nil
 250  * End:
 251  *
 252  * vi: set shiftwidth=4 tabstop=8 expandtab:
 253  * :indentSize=4:tabSize=8:noTabs=true:
 254  */