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/* packet-gopher.c
* Routines for RFC 1436 Gopher protocol dissection
* Copyright 2010, Gerald Combs <gerald@wireshark.org>
*
* Wireshark - Network traffic analyzer
* By Gerald Combs <gerald@wireshark.org>
* Copyright 1998 Gerald Combs
*
* Copied from packet-banana.c
*
* SPDX-License-Identifier: GPL-2.0-or-later
*/
/*
* RFC 1436: https://tools.ietf.org/html/rfc1436
* http://en.wikipedia.org/wiki/Gopher_%28protocol%29
*/
#include "config.h"
#include <epan/packet.h>
#include <epan/prefs.h>
void proto_register_gopher(void);
void proto_reg_handoff_gopher(void);
/* Initialize the protocol and registered fields */
static int proto_gopher;
static int hf_gopher_request;
static int hf_gopher_dir_item;
static int hf_gopher_di_type;
static int hf_gopher_di_name;
static int hf_gopher_di_selector;
static int hf_gopher_di_host;
static int hf_gopher_di_port;
static int hf_gopher_unknown;
/* Initialize the subtree pointers */
static int ett_gopher;
static int ett_dir_item;
static dissector_handle_t gopher_handle;
/* RFC 1436 section 3.8 */
static const value_string item_types[] = {
{ '+', "Redundant server" },
{ '0', "Text file" },
{ '1', "Menu" },
{ '2', "CSO phone book entity" },
{ '3', "Error" },
{ '4', "BinHexed Macintosh file" },
{ '5', "DOS binary file" },
{ '6', "Uuencoded file" },
{ '7', "Index server" },
{ '8', "Telnet session" },
{ '9', "Binary file" },
{ 'g', "GIF file" },
{ 'h', "HTML file" }, /* Not in RFC 1436 */
{ 'i', "Informational message"}, /* Not in RFC 1436 */
{ 'I', "Image file" },
{ 's', "Audio file" }, /* Not in RFC 1436 */
{ 'T', "Tn3270 session" },
{ 0, NULL }
};
#define TCP_DEFAULT_RANGE "70"
static range_t *gopher_tcp_range;
/* Returns true if the packet is from a client */
static bool
is_client(packet_info *pinfo) {
return value_is_in_range(gopher_tcp_range, pinfo->destport);
}
/* Name + Tab + Selector + Tab + Host + Tab + Port */
#define MAX_DIR_LINE_LEN (70 + 1 + 255 + 1 + 255 + 1 + 5)
#define MIN_DIR_LINE_LEN (0 + 1 + 0 + 1 + 1 + 1 + 1)
static bool
find_dir_tokens(tvbuff_t *tvb, int name_start, int *sel_start, int *host_start, int *port_start, int *line_len, int *next_offset) {
int remain;
if (tvb_captured_length_remaining(tvb, name_start) < MIN_DIR_LINE_LEN)
return false;
if (! (sel_start && host_start && port_start && line_len && next_offset) )
return false;
*line_len = tvb_find_line_end(tvb, name_start, MAX_DIR_LINE_LEN, next_offset, false);
if (*line_len < MIN_DIR_LINE_LEN)
return false;
remain = *line_len;
*sel_start = tvb_find_uint8(tvb, name_start, remain, '\t') + 1;
if (*sel_start < name_start + 1)
return false;
remain -= *sel_start - name_start;
*host_start = tvb_find_uint8(tvb, *sel_start, remain, '\t') + 1;
if (*host_start < *sel_start + 1)
return false;
remain -= *host_start - *sel_start;
*port_start = tvb_find_uint8(tvb, *host_start, remain, '\t') + 1;
if (*port_start < *host_start + 1)
return false;
return true;
}
/* Dissect the packets */
static int
dissect_gopher(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data _U_) {
proto_item *ti;
proto_tree *gopher_tree, *dir_tree = NULL;
bool client = is_client(pinfo);
int line_len;
const char *request = "[Invalid request]";
bool is_dir = false;
int offset = 0, next_offset;
int sel_start, host_start, port_start;
char *name;
/* Fill in our protocol and info columns */
col_set_str(pinfo->cinfo, COL_PROTOCOL, "Gopher");
if (client) {
line_len = tvb_find_line_end(tvb, 0, -1, NULL, false);
if (line_len == 0) {
request = "[Directory list]";
} else if (line_len > 0) {
request = tvb_get_string_enc(pinfo->pool, tvb, 0, line_len, ENC_ASCII);
}
col_add_fstr(pinfo->cinfo, COL_INFO, "Request: %s", request);
} else {
col_set_str(pinfo->cinfo, COL_INFO, "Response");
}
if (tree) {
/* Create display subtree for the protocol */
ti = proto_tree_add_item(tree, proto_gopher, tvb, 0, -1, ENC_NA);
gopher_tree = proto_item_add_subtree(ti, ett_gopher);
if (client) {
proto_item_append_text(ti, " request: %s", request);
proto_tree_add_string(gopher_tree, hf_gopher_request, tvb,
0, -1, request);
} else {
proto_item_append_text(ti, " response: ");
while (find_dir_tokens(tvb, offset + 1, &sel_start, &host_start, &port_start, &line_len, &next_offset)) {
if (!is_dir) { /* First time */
proto_item_append_text(ti, "[Directory list]");
col_append_str(pinfo->cinfo, COL_INFO, ": [Directory list]");
}
name = tvb_get_string_enc(pinfo->pool, tvb, offset + 1, sel_start - offset - 2, ENC_ASCII);
ti = proto_tree_add_string(gopher_tree, hf_gopher_dir_item, tvb,
offset, line_len + 1, name);
dir_tree = proto_item_add_subtree(ti, ett_dir_item);
proto_tree_add_item(dir_tree, hf_gopher_di_type, tvb, offset, 1, ENC_ASCII|ENC_NA);
proto_tree_add_item(dir_tree, hf_gopher_di_name, tvb, offset + 1,
sel_start - offset - 2, ENC_ASCII);
proto_tree_add_item(dir_tree, hf_gopher_di_selector, tvb, sel_start,
host_start - sel_start - 1, ENC_ASCII);
proto_tree_add_item(dir_tree, hf_gopher_di_host, tvb, host_start,
port_start - host_start - 1, ENC_ASCII);
proto_tree_add_item(dir_tree, hf_gopher_di_port, tvb, port_start,
line_len - (port_start - offset - 1), ENC_ASCII);
is_dir = true;
offset = next_offset;
}
if (!is_dir) {
proto_item_append_text(ti, "[Unknown]");
proto_tree_add_item(gopher_tree, hf_gopher_unknown, tvb, 0, -1, ENC_ASCII);
}
}
}
/* Return the amount of data this dissector was able to dissect */
return tvb_captured_length(tvb);
}
/* Preference callbacks */
static void
gopher_prefs_apply(void) {
gopher_tcp_range = prefs_get_range_value("gopher", "tcp.port");
}
/* Register the protocol with Wireshark */
void
proto_register_gopher(void)
{
static hf_register_info hf[] = {
{ &hf_gopher_request,
{ "Gopher client request", "gopher.request",
FT_STRING, BASE_NONE, NULL, 0,
NULL, HFILL }
},
{ &hf_gopher_dir_item,
{ "Directory item", "gopher.directory",
FT_STRING, BASE_NONE, NULL, 0,
NULL, HFILL }
},
{ &hf_gopher_di_type,
{ "Type", "gopher.directory.type",
FT_CHAR, BASE_HEX, VALS(item_types), 0,
NULL, HFILL }
},
{ &hf_gopher_di_name,
{ "Name", "gopher.directory.name",
FT_STRING, BASE_NONE, NULL, 0,
NULL, HFILL }
},
{ &hf_gopher_di_selector,
{ "Selector", "gopher.directory.selector",
FT_STRING, BASE_NONE, NULL, 0,
NULL, HFILL }
},
{ &hf_gopher_di_host,
{ "Host", "gopher.directory.host",
FT_STRING, BASE_NONE, NULL, 0,
NULL, HFILL }
},
{ &hf_gopher_di_port,
{ "Port", "gopher.directory.port",
FT_STRING, BASE_NONE, NULL, 0,
NULL, HFILL }
},
{ &hf_gopher_unknown,
{ "Unknown Gopher transaction data", "gopher.unknown",
FT_STRING, BASE_NONE, NULL, 0,
NULL, HFILL }
}
};
/* Setup protocol subtree array */
static int *ett[] = {
&ett_gopher,
&ett_dir_item
};
/* Register the protocol name and description */
proto_gopher = proto_register_protocol("Gopher", "Gopher", "gopher");
/* Register the dissector handle */
gopher_handle = register_dissector("gopher", dissect_gopher, proto_gopher);
/* Required function calls to register the header fields and subtrees used */
proto_register_field_array(proto_gopher, hf, array_length(hf));
proto_register_subtree_array(ett, array_length(ett));
/* Preferences for this module are generated when registering with
dissector tables and need the callback function to get the
port range values
*/
prefs_register_protocol(proto_gopher, gopher_prefs_apply);
}
void
proto_reg_handoff_gopher(void)
{
dissector_add_uint_range_with_preference("tcp.port", TCP_DEFAULT_RANGE, gopher_handle);
gopher_prefs_apply();
}
/*
* Editor modelines - https://www.wireshark.org/tools/modelines.html
*
* Local variables:
* c-basic-offset: 4
* tab-width: 8
* indent-tabs-mode: nil
* End:
*
* vi: set shiftwidth=4 tabstop=8 expandtab:
* :indentSize=4:tabSize=8:noTabs=true:
*/
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