epan/dissectors/packet-laplink.c

   1 /* packet-laplink.c
   2  * Routines for laplink dissection
   3  * Copyright 2003, Brad Hards <bradh@frogmouth.net>
   4  *
   5  * Wireshark - Network traffic analyzer
   6  * By Gerald Combs <gerald@wireshark.org>
   7  * Copyright 1998 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 #include "packet-tcp.h"
  17 #include <epan/prefs.h>
  18
  19 void proto_register_laplink(void);
  20 void proto_reg_handoff_laplink(void);
  21
  22 static dissector_handle_t laplink_udp_handle;
  23 static dissector_handle_t laplink_tcp_handle;
  24
  25 #define TCP_PORT_LAPLINK 1547
  26 #define UDP_PORT_LAPLINK 1547
  27
  28 /* Initialize the protocol and registered fields */
  29 static int proto_laplink;
  30 static int hf_laplink_udp_ident;
  31 static int hf_laplink_udp_name;
  32 static int hf_laplink_tcp_ident;
  33 static int hf_laplink_tcp_length;
  34 static int hf_laplink_tcp_data;
  35
  36 /* Initialize the subtree pointers */
  37 static int ett_laplink;
  38
  39 static const value_string laplink_udp_magic[] = {
  40         { 0x0f010000, "Name Solicitation" },
  41         { 0xf0000200, "Name Reply" },
  42         { 0, NULL }
  43 };
  44
  45 static const value_string laplink_tcp_magic[] = {
  46         { 0xff08c000, "Unknown TCP query - connection?" },
  47         { 0xff08c200, "Unknown TCP query - connection?" },
  48         { 0xff0bc000, "Unknown TCP query - connection?" },
  49         { 0xff0bc200, "Unknown TCP query - connection?" },
  50         { 0xff10c000, "Unknown TCP response - connection?" },
  51         { 0xff10c200, "Unknown TCP response - connection?" },
  52         { 0xff11c000, "Unknown TCP query/response - directory list or file transfer?" },
  53         { 0xff11c200, "Unknown TCP query - directory list or file request?" },
  54         { 0xff13c000, "Unknown TCP response - connection?" },
  55         { 0xff13c200, "Unknown TCP response - connection?" },
  56         { 0xff14c000, "Unknown TCP response - directory list or file transfer?" },
  57         { 0, NULL }
  58 };
  59
  60 static bool laplink_desegment = true;
  61
  62 /* Code to actually dissect the packets - UDP */
  63 static int
  64 dissect_laplink_udp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data _U_)
  65 {
  66         int offset = 0;
  67         proto_item *ti;
  68         proto_tree *laplink_tree;
  69         uint32_t udp_ident;
  70         const char *udp_ident_string;
  71
  72         /*
  73          * Make sure the identifier is reasonable.
  74          */
  75         if (!tvb_bytes_exist(tvb, offset, 4))
  76                 return 0;       /* not enough bytes to check */
  77         udp_ident = tvb_get_ntohl(tvb, offset);
  78         udp_ident_string = try_val_to_str(udp_ident, laplink_udp_magic);
  79         if (udp_ident_string == NULL)
  80                 return 0;       /* unknown */
  81
  82 /* Make entries in Protocol column and Info column on summary display */
  83         col_set_str(pinfo->cinfo, COL_PROTOCOL, "Laplink");
  84
  85         col_add_str(pinfo->cinfo, COL_INFO, udp_ident_string);
  86
  87         if (tree){
  88                 ti = proto_tree_add_item(tree, proto_laplink, tvb, 0, -1, ENC_NA);
  89                 laplink_tree = proto_item_add_subtree(ti, ett_laplink);
  90
  91                 proto_tree_add_uint(laplink_tree, hf_laplink_udp_ident, tvb, offset, 4, udp_ident);
  92                 offset += 4;
  93
  94                 proto_tree_add_item(laplink_tree, hf_laplink_udp_name, tvb, offset, -1, ENC_ASCII);
  95         }
  96         return tvb_captured_length(tvb);
  97 }
  98
  99 /* Code to actually dissect the packets - TCP aspects*/
 100 static int
 101 dissect_laplink_tcp_pdu(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
 102 {
 103         int offset = 0;
 104         int length = 0;
 105         proto_item *ti;
 106         proto_tree *laplink_tree;
 107         uint32_t tcp_ident;
 108
 109 /* Make entries in Protocol column and Info column on summary display */
 110         col_set_str(pinfo->cinfo, COL_PROTOCOL, "Laplink");
 111
 112         tcp_ident = tvb_get_ntohl(tvb, offset);
 113         col_add_str(pinfo->cinfo, COL_INFO,
 114                             val_to_str(tcp_ident, laplink_tcp_magic, "TCP TBA (%u)"));
 115
 116         if (tree){
 117                 ti = proto_tree_add_item(tree, proto_laplink, tvb, 0, -1, ENC_NA);
 118
 119
 120                 laplink_tree = proto_item_add_subtree(ti, ett_laplink);
 121
 122                 proto_tree_add_item(laplink_tree, hf_laplink_tcp_ident, tvb, offset, 4, ENC_BIG_ENDIAN);
 123                 offset += 4;
 124
 125                 length = tvb_get_ntohs(tvb, offset);
 126                 proto_tree_add_item(laplink_tree, hf_laplink_tcp_length, tvb, offset, 2, ENC_BIG_ENDIAN);
 127                 offset += 2;
 128
 129                 proto_tree_add_item(laplink_tree, hf_laplink_tcp_data, tvb, offset, length, ENC_NA);
 130
 131 /* Continue adding tree items to process the packet here */
 132
 133         }
 134
 135         return tvb_captured_length(tvb);
 136 /* If this protocol has a sub-dissector call it here, see section 1.8 */
 137 }
 138
 139 static unsigned
 140 get_laplink_pdu_len(packet_info *pinfo _U_, tvbuff_t *tvb, int offset, void *data _U_)
 141 {
 142         unsigned plen;
 143         /*
 144          * The length doesn't include the length or ident fields; add those in.
 145          */
 146         plen = (tvb_get_ntohs(tvb, offset+4) + 2 + 4);
 147         return plen;
 148 }
 149
 150 static int
 151 dissect_laplink_tcp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data)
 152 {
 153         tcp_dissect_pdus(tvb, pinfo, tree, laplink_desegment,
 154                          6, get_laplink_pdu_len,
 155                          dissect_laplink_tcp_pdu, data);
 156         return tvb_captured_length(tvb);
 157 }
 158
 159
 160 /* Register the protocol with Wireshark */
 161
 162 void
 163 proto_register_laplink(void)
 164 {
 165
 166 /* Setup list of header fields  See Section 1.6.1 for details*/
 167         static hf_register_info hf[] = {
 168                 { &hf_laplink_udp_ident,
 169                         { "UDP Ident", "laplink.udp_ident",
 170                         FT_UINT32, BASE_HEX, VALS(laplink_udp_magic), 0x0,
 171                         "Unknown magic", HFILL }
 172                 },
 173                 { &hf_laplink_udp_name,
 174                         { "UDP Name", "laplink.udp_name",
 175                         FT_STRINGZ, BASE_NONE, NULL, 0x0,
 176                         "Machine name", HFILL }
 177                 },
 178                 { &hf_laplink_tcp_ident,
 179                         { "TCP Ident", "laplink.tcp_ident",
 180                         FT_UINT32, BASE_HEX, VALS(laplink_tcp_magic), 0x0,
 181                         "Unknown magic", HFILL }
 182                 },
 183                 { &hf_laplink_tcp_length,
 184                         { "TCP Data payload length", "laplink.tcp_length",
 185                         FT_UINT16, BASE_DEC, NULL, 0x0,
 186                         "Length of remaining payload", HFILL }
 187                 },
 188                 { &hf_laplink_tcp_data,
 189                         { "Unknown TCP data", "laplink.tcp_data",
 190                         FT_BYTES, BASE_NONE, NULL, 0x0,
 191                         NULL, HFILL }
 192                 },
 193         };
 194
 195 /* Setup protocol subtree array */
 196         static int *ett[] = {
 197                 &ett_laplink,
 198         };
 199
 200         module_t *laplink_module;
 201
 202 /* Register the protocol name and description */
 203         proto_laplink = proto_register_protocol("Laplink", "Laplink", "laplink");
 204
 205 /* Required function calls to register the header fields and subtrees used */
 206         proto_register_field_array(proto_laplink, hf, array_length(hf));
 207         proto_register_subtree_array(ett, array_length(ett));
 208
 209         laplink_module = prefs_register_protocol(proto_laplink, NULL);
 210         prefs_register_bool_preference(laplink_module, "desegment_laplink_over_tcp",
 211                                        "Reassemble Laplink over TCP messages spanning multiple TCP segments",
 212                                        "Whether the Laplink dissector should reassemble messages spanning multiple TCP segments."
 213                                        " To use this option, you must also enable \"Allow subdissectors to reassemble TCP streams\" in the TCP protocol settings.",
 214                                        &laplink_desegment);
 215
 216         laplink_tcp_handle = register_dissector("laplink.tcp", dissect_laplink_tcp, proto_laplink);
 217         laplink_udp_handle = register_dissector("laplink.udp", dissect_laplink_udp, proto_laplink);
 218 }
 219
 220
 221 /* If this dissector uses sub-dissector registration add a registration routine.
 222    This format is required because a script is used to find these routines and
 223    create the code that calls these routines.
 224 */
 225 void
 226 proto_reg_handoff_laplink(void)
 227 {
 228         dissector_add_uint_with_preference("tcp.port", TCP_PORT_LAPLINK, laplink_tcp_handle);
 229         dissector_add_uint_with_preference("udp.port", UDP_PORT_LAPLINK, laplink_udp_handle);
 230 }
 231
 232 /*
 233  * Editor modelines  -  https://www.wireshark.org/tools/modelines.html
 234  *
 235  * Local variables:
 236  * c-basic-offset: 8
 237  * tab-width: 8
 238  * indent-tabs-mode: t
 239  * End:
 240  *
 241  * vi: set shiftwidth=8 tabstop=8 noexpandtab:
 242  * :indentSize=8:tabSize=8:noTabs=false:
 243  */