epan/dissectors/packet-gopher.c

   1 /* packet-gopher.c
   2  * Routines for RFC 1436 Gopher protocol dissection
   3  * Copyright 2010, Gerald Combs <gerald@wireshark.org>
   4  *
   5  * Wireshark - Network traffic analyzer
   6  * By Gerald Combs <gerald@wireshark.org>
   7  * Copyright 1998 Gerald Combs
   8  *
   9  * Copied from packet-banana.c
  10  *
  11  * SPDX-License-Identifier: GPL-2.0-or-later
  12  */
  13
  14 /*
  15  * RFC 1436: https://tools.ietf.org/html/rfc1436
  16  * http://en.wikipedia.org/wiki/Gopher_%28protocol%29
  17  */
  18
  19 #include "config.h"
  20
  21 #include <epan/packet.h>
  22 #include <epan/prefs.h>
  23
  24 void proto_register_gopher(void);
  25 void proto_reg_handoff_gopher(void);
  26
  27 /* Initialize the protocol and registered fields */
  28 static int proto_gopher;
  29 static int hf_gopher_request;
  30 static int hf_gopher_dir_item;
  31 static int hf_gopher_di_type;
  32 static int hf_gopher_di_name;
  33 static int hf_gopher_di_selector;
  34 static int hf_gopher_di_host;
  35 static int hf_gopher_di_port;
  36 static int hf_gopher_unknown;
  37
  38 /* Initialize the subtree pointers */
  39 static int ett_gopher;
  40 static int ett_dir_item;
  41
  42 static dissector_handle_t gopher_handle;
  43
  44 /* RFC 1436 section 3.8 */
  45 static const value_string item_types[] = {
  46     { '+',  "Redundant server" },
  47     { '0',  "Text file" },
  48     { '1',  "Menu" },
  49     { '2',  "CSO phone book entity" },
  50     { '3',  "Error" },
  51     { '4',  "BinHexed Macintosh file" },
  52     { '5',  "DOS binary file" },
  53     { '6',  "Uuencoded file" },
  54     { '7',  "Index server" },
  55     { '8',  "Telnet session" },
  56     { '9',  "Binary file" },
  57     { 'g',  "GIF file" },
  58     { 'h',  "HTML file" },              /* Not in RFC 1436 */
  59     { 'i',  "Informational message"},   /* Not in RFC 1436 */
  60     { 'I',  "Image file" },
  61     { 's',  "Audio file" },             /* Not in RFC 1436 */
  62     { 'T',  "Tn3270 session" },
  63     { 0, NULL }
  64 };
  65
  66 #define TCP_DEFAULT_RANGE "70"
  67
  68 static range_t *gopher_tcp_range;
  69
  70 /* Returns true if the packet is from a client */
  71 static bool
  72 is_client(packet_info *pinfo) {
  73     return value_is_in_range(gopher_tcp_range, pinfo->destport);
  74 }
  75
  76 /* Name + Tab + Selector + Tab + Host + Tab + Port */
  77 #define MAX_DIR_LINE_LEN (70 + 1 + 255 + 1 + 255 + 1 + 5)
  78 #define MIN_DIR_LINE_LEN (0 + 1 + 0 + 1 + 1 + 1 + 1)
  79 static bool
  80 find_dir_tokens(tvbuff_t *tvb, int name_start, int *sel_start, int *host_start, int *port_start, int *line_len, int *next_offset) {
  81     int remain;
  82
  83     if (tvb_captured_length_remaining(tvb, name_start) < MIN_DIR_LINE_LEN)
  84         return false;
  85
  86     if (! (sel_start && host_start && port_start && line_len && next_offset) )
  87         return false;
  88
  89     *line_len = tvb_find_line_end(tvb, name_start, MAX_DIR_LINE_LEN, next_offset, false);
  90     if (*line_len < MIN_DIR_LINE_LEN)
  91         return false;
  92
  93     remain = *line_len;
  94     *sel_start = tvb_find_uint8(tvb, name_start, remain, '\t') + 1;
  95     if (*sel_start < name_start + 1)
  96         return false;
  97
  98     remain -= *sel_start - name_start;
  99     *host_start = tvb_find_uint8(tvb, *sel_start, remain, '\t') + 1;
 100     if (*host_start < *sel_start + 1)
 101         return false;
 102
 103     remain -= *host_start - *sel_start;
 104     *port_start = tvb_find_uint8(tvb, *host_start, remain, '\t') + 1;
 105     if (*port_start < *host_start + 1)
 106         return false;
 107
 108     return true;
 109 }
 110
 111 /* Dissect the packets */
 112
 113 static int
 114 dissect_gopher(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data _U_) {
 115     proto_item *ti;
 116     proto_tree *gopher_tree, *dir_tree = NULL;
 117     bool client = is_client(pinfo);
 118     int line_len;
 119     const char *request = "[Invalid request]";
 120     bool is_dir = false;
 121     int offset = 0, next_offset;
 122     int sel_start, host_start, port_start;
 123     char *name;
 124
 125     /* Fill in our protocol and info columns */
 126     col_set_str(pinfo->cinfo, COL_PROTOCOL, "Gopher");
 127
 128     if (client) {
 129         line_len = tvb_find_line_end(tvb, 0, -1, NULL, false);
 130         if (line_len == 0) {
 131             request = "[Directory list]";
 132         } else if (line_len > 0) {
 133             request = tvb_get_string_enc(pinfo->pool, tvb, 0, line_len, ENC_ASCII);
 134         }
 135         col_add_fstr(pinfo->cinfo, COL_INFO, "Request: %s", request);
 136     } else {
 137         col_set_str(pinfo->cinfo, COL_INFO, "Response");
 138     }
 139
 140     if (tree) {
 141         /* Create display subtree for the protocol */
 142         ti = proto_tree_add_item(tree, proto_gopher, tvb, 0, -1, ENC_NA);
 143         gopher_tree = proto_item_add_subtree(ti, ett_gopher);
 144
 145         if (client) {
 146             proto_item_append_text(ti, " request: %s", request);
 147             proto_tree_add_string(gopher_tree, hf_gopher_request, tvb,
 148                                   0, -1, request);
 149         } else {
 150             proto_item_append_text(ti, " response: ");
 151
 152             while (find_dir_tokens(tvb, offset + 1, &sel_start, &host_start, &port_start, &line_len, &next_offset)) {
 153                 if (!is_dir) { /* First time */
 154                     proto_item_append_text(ti, "[Directory list]");
 155                     col_append_str(pinfo->cinfo, COL_INFO, ": [Directory list]");
 156                 }
 157
 158                 name = tvb_get_string_enc(pinfo->pool, tvb, offset + 1, sel_start - offset - 2, ENC_ASCII);
 159                 ti = proto_tree_add_string(gopher_tree, hf_gopher_dir_item, tvb,
 160                                 offset, line_len + 1, name);
 161                 dir_tree = proto_item_add_subtree(ti, ett_dir_item);
 162                 proto_tree_add_item(dir_tree, hf_gopher_di_type, tvb, offset, 1, ENC_ASCII|ENC_NA);
 163                 proto_tree_add_item(dir_tree, hf_gopher_di_name, tvb, offset + 1,
 164                                     sel_start - offset - 2, ENC_ASCII);
 165                 proto_tree_add_item(dir_tree, hf_gopher_di_selector, tvb, sel_start,
 166                                     host_start - sel_start - 1, ENC_ASCII);
 167                 proto_tree_add_item(dir_tree, hf_gopher_di_host, tvb, host_start,
 168                                     port_start - host_start - 1, ENC_ASCII);
 169                 proto_tree_add_item(dir_tree, hf_gopher_di_port, tvb, port_start,
 170                                     line_len - (port_start - offset - 1), ENC_ASCII);
 171                 is_dir = true;
 172                 offset = next_offset;
 173             }
 174
 175             if (!is_dir) {
 176                 proto_item_append_text(ti, "[Unknown]");
 177                 proto_tree_add_item(gopher_tree, hf_gopher_unknown, tvb, 0, -1, ENC_ASCII);
 178             }
 179         }
 180
 181     }
 182
 183     /* Return the amount of data this dissector was able to dissect */
 184     return tvb_captured_length(tvb);
 185 }
 186
 187 /* Preference callbacks */
 188 static void
 189 gopher_prefs_apply(void) {
 190
 191     gopher_tcp_range = prefs_get_range_value("gopher", "tcp.port");
 192 }
 193
 194 /* Register the protocol with Wireshark */
 195
 196 void
 197 proto_register_gopher(void)
 198 {
 199     static hf_register_info hf[] = {
 200         { &hf_gopher_request,
 201             { "Gopher client request", "gopher.request",
 202                 FT_STRING, BASE_NONE, NULL, 0,
 203                 NULL, HFILL }
 204         },
 205
 206         { &hf_gopher_dir_item,
 207             { "Directory item", "gopher.directory",
 208                 FT_STRING, BASE_NONE, NULL, 0,
 209                 NULL, HFILL }
 210         },
 211         { &hf_gopher_di_type,
 212             { "Type", "gopher.directory.type",
 213                 FT_CHAR, BASE_HEX, VALS(item_types), 0,
 214                 NULL, HFILL }
 215         },
 216         { &hf_gopher_di_name,
 217             { "Name", "gopher.directory.name",
 218                 FT_STRING, BASE_NONE, NULL, 0,
 219                 NULL, HFILL }
 220         },
 221         { &hf_gopher_di_selector,
 222             { "Selector", "gopher.directory.selector",
 223                 FT_STRING, BASE_NONE, NULL, 0,
 224                 NULL, HFILL }
 225         },
 226         { &hf_gopher_di_host,
 227             { "Host", "gopher.directory.host",
 228                 FT_STRING, BASE_NONE, NULL, 0,
 229                 NULL, HFILL }
 230         },
 231         { &hf_gopher_di_port,
 232             { "Port", "gopher.directory.port",
 233                 FT_STRING, BASE_NONE, NULL, 0,
 234                 NULL, HFILL }
 235         },
 236
 237         { &hf_gopher_unknown,
 238             { "Unknown Gopher transaction data", "gopher.unknown",
 239                 FT_STRING, BASE_NONE, NULL, 0,
 240                 NULL, HFILL }
 241         }
 242     };
 243
 244     /* Setup protocol subtree array */
 245     static int *ett[] = {
 246         &ett_gopher,
 247         &ett_dir_item
 248     };
 249
 250     /* Register the protocol name and description */
 251     proto_gopher = proto_register_protocol("Gopher", "Gopher", "gopher");
 252
 253     /* Register the dissector handle */
 254     gopher_handle = register_dissector("gopher", dissect_gopher, proto_gopher);
 255
 256     /* Required function calls to register the header fields and subtrees used */
 257     proto_register_field_array(proto_gopher, hf, array_length(hf));
 258     proto_register_subtree_array(ett, array_length(ett));
 259
 260     /* Preferences for this module are generated when registering with
 261        dissector tables and need the callback function to get the
 262        port range values
 263      */
 264     prefs_register_protocol(proto_gopher, gopher_prefs_apply);
 265 }
 266
 267 void
 268 proto_reg_handoff_gopher(void)
 269 {
 270     dissector_add_uint_range_with_preference("tcp.port", TCP_DEFAULT_RANGE, gopher_handle);
 271     gopher_prefs_apply();
 272 }
 273
 274 /*
 275  * Editor modelines  -  https://www.wireshark.org/tools/modelines.html
 276  *
 277  * Local variables:
 278  * c-basic-offset: 4
 279  * tab-width: 8
 280  * indent-tabs-mode: nil
 281  * End:
 282  *
 283  * vi: set shiftwidth=4 tabstop=8 expandtab:
 284  * :indentSize=4:tabSize=8:noTabs=true:
 285  */
 286
 287