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  * $Id$
   6  *
   7  * Wireshark - Network traffic analyzer
   8  * By Gerald Combs <gerald@wireshark.org>
   9  * Copyright 1998 Gerald Combs
  10  *
  11  * Copied from packet-banana.c
  12  *
  13  * This program is free software; you can redistribute it and/or
  14  * modify it under the terms of the GNU General Public License
  15  * as published by the Free Software Foundation; either version 2
  16  * of the License, or (at your option) any later version.
  17  *
  18  * This program is distributed in the hope that it will be useful,
  19  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  20  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  21  * GNU General Public License for more details.
  22  *
  23  * You should have received a copy of the GNU General Public License
  24  * along with this program; if not, write to the Free Software
  25  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
  26  */
  27
  28 /*
  29  * RFC 1436: http://tools.ietf.org/html/rfc1436
  30  * http://en.wikipedia.org/wiki/Gopher_%28protocol%29
  31  */
  32
  33 #include "config.h"
  34
  35 #include <glib.h>
  36
  37 #include <epan/packet.h>
  38 #include <epan/prefs.h>
  39
  40 /* Initialize the protocol and registered fields */
  41 static int proto_gopher = -1;
  42 static int hf_gopher_request = -1;
  43 static int hf_gopher_dir_item = -1;
  44 static int hf_gopher_di_type = -1;
  45 static int hf_gopher_di_name = -1;
  46 static int hf_gopher_di_selector = -1;
  47 static int hf_gopher_di_host = -1;
  48 static int hf_gopher_di_port = -1;
  49 static int hf_gopher_unknown = -1;
  50
  51 /* Initialize the subtree pointers */
  52 static gint ett_gopher = -1;
  53 static gint ett_dir_item = -1;
  54
  55 static dissector_handle_t gopher_handle;
  56
  57 /* RFC 1436 section 3.8 */
  58 static const value_string item_types[] = {
  59     { '+',  "Redundant server" },
  60     { '0',  "Text file" },
  61     { '1',  "Menu" },
  62     { '2',  "CSO phone book entity" },
  63     { '3',  "Error" },
  64     { '4',  "BinHexed Macintosh file" },
  65     { '5',  "DOS binary file" },
  66     { '6',  "Uuencoded file" },
  67     { '7',  "Index server" },
  68     { '8',  "Telnet session" },
  69     { '9',  "Binary file" },
  70     { 'g',  "GIF file" },
  71     { 'h',  "HTML file" },              /* Not in RFC 1436 */
  72     { 'i',  "Informational message"},   /* Not in RFC 1436 */
  73     { 'I',  "Image file" },
  74     { 's',  "Audio file" },             /* Not in RFC 1436 */
  75     { 'T',  "Tn3270 session" },
  76     { 0, NULL }
  77 };
  78
  79 #define TCP_DEFAULT_RANGE "70"
  80
  81 static range_t *global_gopher_tcp_range = NULL;
  82 static range_t *gopher_tcp_range = NULL;
  83
  84 /* Returns TRUE if the packet is from a client */
  85 static gboolean
  86 is_client(packet_info *pinfo) {
  87     if (value_is_in_range(gopher_tcp_range, pinfo->destport)) {
  88         return TRUE;
  89     }
  90     return FALSE;
  91 }
  92
  93 /* Name + Tab + Selector + Tab + Host + Tab + Port */
  94 #define MAX_DIR_LINE_LEN (70 + 1 + 255 + 1 + 255 + 1 + 5)
  95 #define MIN_DIR_LINE_LEN (0 + 1 + 0 + 1 + 1 + 1 + 1)
  96 static gboolean
  97 find_dir_tokens(tvbuff_t *tvb, gint name_start, gint *sel_start, gint *host_start, gint *port_start, gint *line_len, gint *next_offset) {
  98     gint remain;
  99
 100     if (tvb_length_remaining(tvb, name_start) < MIN_DIR_LINE_LEN)
 101         return FALSE;
 102
 103     if (! (sel_start && host_start && port_start && line_len && next_offset) )
 104         return FALSE;
 105
 106     *line_len = tvb_find_line_end(tvb, name_start, MAX_DIR_LINE_LEN, next_offset, FALSE);
 107     if (*line_len < MIN_DIR_LINE_LEN)
 108         return FALSE;
 109
 110     remain = *line_len;
 111     *sel_start = tvb_find_guint8(tvb, name_start, remain, '\t') + 1;
 112     if (*sel_start < name_start + 1)
 113         return FALSE;
 114
 115     remain -= *sel_start - name_start;
 116     *host_start = tvb_find_guint8(tvb, *sel_start, remain, '\t') + 1;
 117     if (*host_start < *sel_start + 1)
 118         return FALSE;
 119
 120     remain -= *host_start - *sel_start;
 121     *port_start = tvb_find_guint8(tvb, *host_start, remain, '\t') + 1;
 122     if (*port_start < *host_start + 1)
 123         return FALSE;
 124
 125     return TRUE;
 126 }
 127
 128 /* Dissect the packets */
 129
 130 static int
 131 dissect_gopher(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data _U_) {
 132     proto_item *ti;
 133     proto_tree *gopher_tree, *dir_tree = NULL;
 134     gboolean client = is_client(pinfo);
 135     gint line_len;
 136     const gchar *request = "[Invalid request]";
 137     gboolean is_dir = FALSE;
 138     gint offset = 0, next_offset;
 139     gint sel_start, host_start, port_start;
 140     gchar *name;
 141
 142     /* Fill in our protocol and info columns */
 143     col_set_str(pinfo->cinfo, COL_PROTOCOL, "Gopher");
 144
 145     if (client) {
 146         line_len = tvb_find_line_end(tvb, 0, -1, NULL, FALSE);
 147         if (line_len == 0) {
 148             request = "[Directory list]";
 149         } else if (line_len > 0) {
 150             request = tvb_get_string(wmem_packet_scope(), tvb, 0, line_len);
 151         }
 152         col_add_fstr(pinfo->cinfo, COL_INFO, "Request: %s", request);
 153     } else {
 154         col_add_fstr(pinfo->cinfo, COL_INFO, "Response");
 155     }
 156
 157     if (tree) {
 158         /* Create display subtree for the protocol */
 159         ti = proto_tree_add_item(tree, proto_gopher, tvb, 0, -1, ENC_NA);
 160         gopher_tree = proto_item_add_subtree(ti, ett_gopher);
 161
 162         if (client) {
 163             proto_item_append_text(ti, " request: %s", request);
 164             proto_tree_add_string(gopher_tree, hf_gopher_request, tvb,
 165                                   0, -1, request);
 166         } else {
 167             proto_item_append_text(ti, " response: ");
 168
 169             while (find_dir_tokens(tvb, offset + 1, &sel_start, &host_start, &port_start, &line_len, &next_offset)) {
 170                 if (!is_dir) { /* First time */
 171                     proto_item_append_text(ti, "[Directory list]");
 172                     col_append_str(pinfo->cinfo, COL_INFO, ": [Directory list]");
 173                 }
 174
 175                 name = tvb_get_string(wmem_packet_scope(), tvb, offset + 1, sel_start - offset - 2);
 176                 ti = proto_tree_add_string(gopher_tree, hf_gopher_dir_item, tvb,
 177                                 offset, line_len + 1, name);
 178                 dir_tree = proto_item_add_subtree(ti, ett_dir_item);
 179                 proto_tree_add_item(dir_tree, hf_gopher_di_type, tvb, offset, 1, ENC_BIG_ENDIAN);
 180                 proto_tree_add_item(dir_tree, hf_gopher_di_name, tvb, offset + 1,
 181                                     sel_start - offset - 2, ENC_ASCII|ENC_NA);
 182                 proto_tree_add_item(dir_tree, hf_gopher_di_selector, tvb, sel_start,
 183                                     host_start - sel_start - 1, ENC_ASCII|ENC_NA);
 184                 proto_tree_add_item(dir_tree, hf_gopher_di_host, tvb, host_start,
 185                                     port_start - host_start - 1, ENC_ASCII|ENC_NA);
 186                 proto_tree_add_item(dir_tree, hf_gopher_di_port, tvb, port_start,
 187                                     line_len - (port_start - offset - 1), ENC_ASCII|ENC_NA);
 188                 is_dir = TRUE;
 189                 offset = next_offset;
 190             }
 191
 192             if (!is_dir) {
 193                 proto_item_append_text(ti, "[Unknown]");
 194                 proto_tree_add_item(gopher_tree, hf_gopher_unknown, tvb, 0, -1, ENC_ASCII|ENC_NA);
 195             }
 196         }
 197
 198     }
 199
 200     /* Return the amount of data this dissector was able to dissect */
 201     return tvb_length(tvb);
 202 }
 203
 204 /* Preference callbacks */
 205 static void
 206 range_delete_gopher_tcp_callback(guint32 port) {
 207       dissector_delete_uint("tcp.port", port, gopher_handle);
 208 }
 209
 210 static void
 211 range_add_gopher_tcp_callback(guint32 port) {
 212     dissector_add_uint("tcp.port", port, gopher_handle);
 213 }
 214
 215 static void
 216 gopher_prefs_apply(void) {
 217     range_foreach(gopher_tcp_range, range_delete_gopher_tcp_callback);
 218     g_free(gopher_tcp_range);
 219     gopher_tcp_range = range_copy(global_gopher_tcp_range);
 220     range_foreach(gopher_tcp_range, range_add_gopher_tcp_callback);
 221 }
 222
 223 /* Register the protocol with Wireshark */
 224
 225 void
 226 proto_register_gopher(void)
 227 {
 228     static hf_register_info hf[] = {
 229         { &hf_gopher_request,
 230             { "Gopher client request", "gopher.request",
 231                 FT_STRING, BASE_NONE, NULL, 0,
 232                 NULL, HFILL }
 233         },
 234
 235         { &hf_gopher_dir_item,
 236             { "Directory item", "gopher.directory",
 237                 FT_STRING, BASE_NONE, NULL, 0,
 238                 NULL, HFILL }
 239         },
 240         { &hf_gopher_di_type,
 241             { "Type", "gopher.directory.type",
 242                 FT_UINT8, BASE_HEX, VALS(item_types), 0,
 243                 NULL, HFILL }
 244         },
 245         { &hf_gopher_di_name,
 246             { "Name", "gopher.directory.name",
 247                 FT_STRING, BASE_NONE, NULL, 0,
 248                 NULL, HFILL }
 249         },
 250         { &hf_gopher_di_selector,
 251             { "Selector", "gopher.directory.selector",
 252                 FT_STRING, BASE_NONE, NULL, 0,
 253                 NULL, HFILL }
 254         },
 255         { &hf_gopher_di_host,
 256             { "Host", "gopher.directory.host",
 257                 FT_STRING, BASE_NONE, NULL, 0,
 258                 NULL, HFILL }
 259         },
 260         { &hf_gopher_di_port,
 261             { "Port", "gopher.directory.port",
 262                 FT_STRING, BASE_NONE, NULL, 0,
 263                 NULL, HFILL }
 264         },
 265
 266         { &hf_gopher_unknown,
 267             { "Unknown Gopher transaction data", "gopher.unknown",
 268                 FT_STRING, BASE_NONE, NULL, 0,
 269                 NULL, HFILL }
 270         }
 271     };
 272
 273     module_t *gopher_module;
 274
 275     /* Setup protocol subtree array */
 276     static gint *ett[] = {
 277         &ett_gopher,
 278         &ett_dir_item
 279     };
 280
 281     /* Register the protocol name and description */
 282     proto_gopher = proto_register_protocol("Gopher",
 283         "Gopher", "gopher");
 284
 285     /* Required function calls to register the header fields and subtrees used */
 286     proto_register_field_array(proto_gopher, hf, array_length(hf));
 287     proto_register_subtree_array(ett, array_length(ett));
 288
 289     /* Initialize dissector preferences */
 290     gopher_module = prefs_register_protocol(proto_gopher, gopher_prefs_apply);
 291
 292     range_convert_str(&global_gopher_tcp_range, TCP_DEFAULT_RANGE, 65535);
 293     gopher_tcp_range = range_empty();
 294     prefs_register_range_preference(gopher_module, "tcp.port", "TCP Ports",
 295                                     "TCP Ports range",
 296                                     &global_gopher_tcp_range, 65535);
 297 }
 298
 299 void
 300 proto_reg_handoff_gopher(void)
 301 {
 302     gopher_handle = new_create_dissector_handle(dissect_gopher, proto_gopher);
 303     gopher_prefs_apply();
 304 }
 305
 306 /*
 307  * Editor modelines  -  http://www.wireshark.org/tools/modelines.html
 308  *
 309  * Local variables:
 310  * c-basic-offset: 4
 311  * tab-width: 8
 312  * indent-tabs-mode: nil
 313  * End:
 314  *
 315  * vi: set shiftwidth=4 tabstop=8 expandtab:
 316  * :indentSize=4:tabSize=8:noTabs=true:
 317  */
 318
 319