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wireshark/epan/dissectors/packet-rlogin.c

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/* packet-rlogin.c
* Routines for unix rlogin packet dissection
* Copyright 2000, Jeffrey C. Foster <jfoste[AT]woodward.com>
*
* Wireshark - Network traffic analyzer
* By Gerald Combs <gerald@wireshark.org>
* Copyright 1998 Gerald Combs
*
* Based upon RFC-1282 - BSD Rlogin
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include "config.h"
#include <stdlib.h>
#include <epan/packet.h>
#include <epan/expert.h>
#include <wsutil/strtoi.h>
#include "packet-tcp.h"
#define RLOGIN_PORT 513
void proto_register_rlogin(void);
void proto_reg_handoff_rlogin(void);
static int proto_rlogin = -1;
static int ett_rlogin = -1;
static int ett_rlogin_window = -1;
static int ett_rlogin_user_info = -1;
static int ett_rlogin_window_rows = -1;
static int ett_rlogin_window_cols = -1;
static int ett_rlogin_window_x_pixels = -1;
static int ett_rlogin_window_y_pixels = -1;
static int hf_user_info = -1;
static int hf_client_startup_flag = -1;
static int hf_startup_info_received_flag = -1;
static int hf_user_info_client_user_name = -1;
static int hf_user_info_server_user_name = -1;
static int hf_user_info_terminal_type = -1;
static int hf_user_info_terminal_speed = -1;
static int hf_control_message = -1;
static int hf_magic_cookie = -1;
static int hf_window_info = -1;
static int hf_window_info_ss = -1;
static int hf_window_info_rows = -1;
static int hf_window_info_cols = -1;
static int hf_window_info_x_pixels = -1;
static int hf_window_info_y_pixels = -1;
static int hf_data = -1;
static expert_field ei_rlogin_termlen_invalid = EI_INIT;
static const value_string control_message_vals[] =
{
{ 0x02, "Clear buffer" },
{ 0x10, "Raw mode" },
{ 0x20, "Cooked mode" },
{ 0x80, "Window size request" },
{ 0, NULL }
};
typedef enum {
NONE=0,
USER_INFO_WAIT=1,
DONE=2
} session_state_t;
#define NAME_LEN 32
typedef struct {
session_state_t state;
guint32 info_framenum;
char user_name[NAME_LEN];
} rlogin_hash_entry_t;
/* Decoder State Machine. Currently only used to snoop on
client-user-name as sent by the client up connection establishment.
*/
static void
rlogin_state_machine(rlogin_hash_entry_t *hash_info, tvbuff_t *tvb, packet_info *pinfo)
{
guint length;
gint stringlen;
/* Won't change state if already seen this packet */
if (pinfo->fd->flags.visited)
{
return;
}
/* rlogin stream decoder */
/* Just watch for the second packet from client with the user name and */
/* terminal type information. */
if (pinfo->destport != RLOGIN_PORT)
{
return;
}
/* exit if already passed username in conversation */
if (hash_info->state == DONE)
{
return;
}
/* exit if no data */
length = tvb_captured_length(tvb);
if (length == 0)
{
return;
}
if (hash_info->state == NONE)
{
/* new connection*/
if (tvb_get_guint8(tvb, 0) != '\0')
{
/* We expected a null, but didn't get one; quit. */
hash_info->state = DONE;
return;
}
else
{
if (length <= 1)
{
/* Still waiting for data */
hash_info->state = USER_INFO_WAIT;
}
else
{
/* Have info, store frame number */
hash_info->state = DONE;
hash_info->info_framenum = pinfo->num;
}
}
}
/* expect user data here */
/* TODO: may need to do more checking here? */
else
if (hash_info->state == USER_INFO_WAIT)
{
/* Store frame number here */
hash_info->state = DONE;
hash_info->info_framenum = pinfo->num;
/* Work out length of string to copy */
stringlen = tvb_strnlen(tvb, 0, NAME_LEN);
if (stringlen == -1)
stringlen = NAME_LEN - 1; /* no '\0' found */
else if (stringlen > NAME_LEN - 1)
stringlen = NAME_LEN - 1; /* name too long */
/* Copy and terminate string into hash name */
tvb_memcpy(tvb, (guint8 *)hash_info->user_name, 0, stringlen);
hash_info->user_name[stringlen] = '\0';
col_append_str(pinfo->cinfo, COL_INFO, ", (User information)");
}
}
/* Dissect details of packet */
static void rlogin_display(rlogin_hash_entry_t *hash_info,
tvbuff_t *tvb,
packet_info *pinfo,
proto_tree *tree,
struct tcpinfo *tcpinfo)
{
/* Display the proto tree */
int offset = 0;
proto_tree *rlogin_tree, *user_info_tree, *window_tree;
proto_item *ti;
guint length;
int str_len;
gint ti_offset;
proto_item *user_info_item, *window_info_item;
/* Create rlogin subtree */
ti = proto_tree_add_item(tree, proto_rlogin, tvb, 0, -1, ENC_NA);
rlogin_tree = proto_item_add_subtree(ti, ett_rlogin);
/* Return if data empty */
length = tvb_captured_length(tvb);
if (length == 0)
{
return;
}
/*
* XXX - this works only if the urgent pointer points to something
* in this segment; to make it work if the urgent pointer points
* to something past this segment, we'd have to remember the urgent
* pointer setting for this conversation.
*/
if (tcpinfo && IS_TH_URG(tcpinfo->flags) && /* if urgent pointer set */
length >= tcpinfo->urgent_pointer) /* and it's in this frame */
{
/* Get urgent byte into Temp */
int urgent_offset = tcpinfo->urgent_pointer - 1;
guint8 control_byte;
/* Check for text data in front */
if (urgent_offset > offset)
{
proto_tree_add_item(rlogin_tree, hf_data, tvb, offset, urgent_offset, ENC_ASCII|ENC_NA);
}
/* Show control byte */
proto_tree_add_item(rlogin_tree, hf_control_message, tvb,
urgent_offset, 1, ENC_BIG_ENDIAN);
control_byte = tvb_get_guint8(tvb, urgent_offset);
col_append_fstr(pinfo->cinfo, COL_INFO,
" (%s)", val_to_str_const(control_byte, control_message_vals, "Unknown"));
offset = urgent_offset + 1; /* adjust offset */
}
else
if (tvb_get_guint8(tvb, offset) == '\0')
{
/* Startup */
if (pinfo->srcport == RLOGIN_PORT) /* from server */
{
proto_tree_add_item(rlogin_tree, hf_startup_info_received_flag,
tvb, offset, 1, ENC_BIG_ENDIAN);
}
else
{
proto_tree_add_item(rlogin_tree, hf_client_startup_flag,
tvb, offset, 1, ENC_BIG_ENDIAN);
}
++offset;
}
if (!tvb_offset_exists(tvb, offset))
{
/* No more data to check */
return;
}
if (hash_info->info_framenum == pinfo->num)
{
gint info_len;
gint slash_offset;
/* First frame of conversation, assume user info... */
info_len = tvb_captured_length_remaining(tvb, offset);
if (info_len <= 0)
return;
/* User info tree */
user_info_item = proto_tree_add_string_format(rlogin_tree, hf_user_info, tvb,
offset, info_len, FALSE,
"User info (%s)",
tvb_format_text(tvb, offset, info_len));
user_info_tree = proto_item_add_subtree(user_info_item,
ett_rlogin_user_info);
/* Client user name. */
str_len = tvb_strsize(tvb, offset);
proto_tree_add_item(user_info_tree, hf_user_info_client_user_name,
tvb, offset, str_len, ENC_ASCII|ENC_NA);
offset += str_len;
/* Server user name. */
str_len = tvb_strsize(tvb, offset);
proto_tree_add_item(user_info_tree, hf_user_info_server_user_name,
tvb, offset, str_len, ENC_ASCII|ENC_NA);
offset += str_len;
/* Terminal type/speed. */
slash_offset = tvb_find_guint8(tvb, offset, -1, '/');
if (slash_offset != -1)
{
guint8* str = NULL;
guint32 term_len = 0;
gboolean term_len_valid;
proto_item* pi = NULL;
/* Terminal type */
proto_tree_add_item(user_info_tree, hf_user_info_terminal_type,
tvb, offset, slash_offset-offset, ENC_ASCII|ENC_NA);
offset = slash_offset + 1;
/* Terminal speed */
str_len = tvb_strsize(tvb, offset);
str = tvb_get_string_enc(wmem_packet_scope(), tvb, offset, str_len,
ENC_NA|ENC_ASCII);
term_len_valid = ws_strtou32(str, NULL, &term_len);
pi = proto_tree_add_uint(user_info_tree,
hf_user_info_terminal_speed,
tvb, offset, str_len, term_len);
if (!term_len_valid)
expert_add_info(pinfo, pi, &ei_rlogin_termlen_invalid);
offset += str_len;
}
}
if (!tvb_offset_exists(tvb, offset))
{
/* No more data to check */
return;
}
/* Test for terminal information, the data will have 2 0xff bytes */
/* look for first 0xff byte */
ti_offset = tvb_find_guint8(tvb, offset, -1, 0xff);
/* Next byte must also be 0xff */
if (ti_offset != -1 &&
tvb_bytes_exist(tvb, ti_offset + 1, 1) &&
tvb_get_guint8(tvb, ti_offset + 1) == 0xff)
{
guint16 rows, columns;
/* Have found terminal info. */
if (ti_offset > offset)
{
/* There's data before the terminal info. */
proto_tree_add_item(rlogin_tree, hf_data, tvb,
offset, ti_offset - offset, ENC_ASCII|ENC_NA);
}
/* Create window info tree */
window_info_item =
proto_tree_add_item(rlogin_tree, hf_window_info, tvb, offset, 12, ENC_NA);
window_tree = proto_item_add_subtree(window_info_item, ett_rlogin_window);
/* Cookie */
proto_tree_add_item(window_tree, hf_magic_cookie, tvb, offset, 2, ENC_BIG_ENDIAN);
offset += 2;
/* These bytes should be "ss" */
proto_tree_add_item(window_tree, hf_window_info_ss, tvb, offset, 2, ENC_ASCII|ENC_NA);
offset += 2;
/* Character rows */
rows = tvb_get_ntohs(tvb, offset);
proto_tree_add_item(window_tree, hf_window_info_rows, tvb,
offset, 2, ENC_BIG_ENDIAN);
offset += 2;
/* Characters per row */
columns = tvb_get_ntohs(tvb, offset);
proto_tree_add_item(window_tree, hf_window_info_cols, tvb,
offset, 2, ENC_BIG_ENDIAN);
offset += 2;
/* x pixels */
proto_tree_add_item(window_tree, hf_window_info_x_pixels, tvb,
offset, 2, ENC_BIG_ENDIAN);
offset += 2;
/* y pixels */
proto_tree_add_item(window_tree, hf_window_info_y_pixels, tvb,
offset, 2, ENC_BIG_ENDIAN);
offset += 2;
/* Show setting highlights in info column */
col_append_fstr(pinfo->cinfo, COL_INFO, " (rows=%u, cols=%u)",
rows, columns);
}
if (tvb_offset_exists(tvb, offset))
{
/* There's more data in the frame. */
proto_tree_add_item(rlogin_tree, hf_data, tvb, offset, -1, ENC_ASCII|ENC_NA);
}
}
/****************************************************************
* Main dissection function
****************************************************************/
static int
dissect_rlogin(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data)
{
struct tcpinfo *tcpinfo = (struct tcpinfo *)data;
conversation_t *conversation;
rlogin_hash_entry_t *hash_info;
guint length;
gint ti_offset;
/* Get or create conversation */
conversation = find_or_create_conversation(pinfo);
/* Get or create data associated with this conversation */
hash_info = (rlogin_hash_entry_t *)conversation_get_proto_data(conversation, proto_rlogin);
if (!hash_info)
{
/* Populate new data struct... */
hash_info = wmem_new(wmem_file_scope(), rlogin_hash_entry_t);
hash_info->state = NONE;
hash_info->info_framenum = 0; /* no frame has the number 0 */
hash_info->user_name[0] = '\0';
/* ... and store in conversation */
conversation_add_proto_data(conversation, proto_rlogin, hash_info);
}
/* Set protocol column text */
col_set_str(pinfo->cinfo, COL_PROTOCOL, "Rlogin");
/* Set info column */
/* Show user-name if available */
if (hash_info->user_name[0])
{
col_add_fstr(pinfo->cinfo, COL_INFO,
"User name: %s, ", hash_info->user_name);
}
else
{
col_clear(pinfo->cinfo, COL_INFO);
}
/* Work out packet content summary for display */
length = tvb_reported_length(tvb);
if (length != 0)
{
/* Initial NULL byte represents part of connection handshake */
if (tvb_get_guint8(tvb, 0) == '\0')
{
col_append_str(pinfo->cinfo, COL_INFO,
(pinfo->destport == RLOGIN_PORT) ?
"Start Handshake" :
"Startup info received");
}
else
if (tcpinfo && IS_TH_URG(tcpinfo->flags) && length >= tcpinfo->urgent_pointer)
{
/* Urgent pointer inside current data represents a control message */
col_append_str(pinfo->cinfo, COL_INFO, "Control Message");
}
else
{
/* Search for 2 consecutive ff bytes
(signifies window change control message) */
ti_offset = tvb_find_guint8(tvb, 0, -1, 0xff);
if (ti_offset != -1 &&
tvb_bytes_exist(tvb, ti_offset + 1, 1) &&
tvb_get_guint8(tvb, ti_offset + 1) == 0xff)
{
col_append_str(pinfo->cinfo, COL_INFO, "Terminal Info");
}
else
{
/* Show any text data in the frame */
int bytes_to_copy = tvb_captured_length(tvb);
if (bytes_to_copy > 128)
{
/* Truncate to 128 bytes for display */
bytes_to_copy = 128;
}
/* Add data into info column */
col_append_fstr(pinfo->cinfo, COL_INFO,
"Data: %s",
tvb_format_text(tvb, 0, bytes_to_copy));
}
}
}
/* See if conversation state needs to be updated */
rlogin_state_machine(hash_info, tvb, pinfo);
/* Dissect in detail */
rlogin_display(hash_info, tvb, pinfo, tree, tcpinfo);
return tvb_captured_length(tvb);
}
void proto_register_rlogin(void)
{
expert_module_t* expert_rlogin;
static gint *ett[] = {
&ett_rlogin,
&ett_rlogin_window,
&ett_rlogin_window_rows,
&ett_rlogin_window_cols,
&ett_rlogin_window_x_pixels,
&ett_rlogin_window_y_pixels,
&ett_rlogin_user_info
};
static hf_register_info hf[] =
{
{ &hf_user_info,
{ "User Info", "rlogin.user_info", FT_STRING, BASE_NONE,
NULL, 0x0, NULL, HFILL
}
},
{ &hf_client_startup_flag,
{ "Client startup flag", "rlogin.client_startup_flag", FT_UINT8, BASE_HEX,
NULL, 0x0, NULL, HFILL
}
},
{ &hf_startup_info_received_flag,
{ "Startup info received flag", "rlogin.startup_info_received_flag", FT_UINT8, BASE_HEX,
NULL, 0x0, NULL, HFILL
}
},
{ &hf_user_info_client_user_name,
{ "Client-user-name", "rlogin.client_user_name", FT_STRING, BASE_NONE,
NULL, 0x0, NULL, HFILL
}
},
{ &hf_user_info_server_user_name,
{ "Server-user-name", "rlogin.server_user_name", FT_STRING, BASE_NONE,
NULL, 0x0, NULL, HFILL
}
},
{ &hf_user_info_terminal_type,
{ "Terminal-type", "rlogin.terminal_type", FT_STRING, BASE_NONE,
NULL, 0x0, NULL, HFILL
}
},
{ &hf_user_info_terminal_speed,
{ "Terminal-speed", "rlogin.terminal_speed", FT_UINT32, BASE_DEC,
NULL, 0x0, NULL, HFILL
}
},
{ &hf_control_message,
{ "Control message", "rlogin.control_message", FT_UINT8, BASE_HEX,
VALS(control_message_vals), 0x0, NULL, HFILL
}
},
{ &hf_magic_cookie,
{ "Magic Cookie", "rlogin.magic_cookie", FT_UINT16, BASE_HEX,
NULL, 0x0, NULL, HFILL
}
},
{ &hf_window_info,
{ "Window Info", "rlogin.window_size", FT_NONE, BASE_NONE,
NULL, 0x0, NULL, HFILL
}
},
{ &hf_window_info_ss,
{ "Window size marker", "rlogin.window_size.ss", FT_STRING, BASE_NONE,
NULL, 0x0, NULL, HFILL
}
},
{ &hf_window_info_rows,
{ "Rows", "rlogin.window_size.rows", FT_UINT16, BASE_DEC,
NULL, 0x0, NULL, HFILL
}
},
{ &hf_window_info_cols,
{ "Columns", "rlogin.window_size.cols", FT_UINT16, BASE_DEC,
NULL, 0x0, NULL, HFILL
}
},
{ &hf_window_info_x_pixels,
{ "X Pixels", "rlogin.window_size.x_pixels", FT_UINT16, BASE_DEC,
NULL, 0x0, NULL, HFILL
}
},
{ &hf_window_info_y_pixels,
{ "Y Pixels", "rlogin.window_size.y_pixels", FT_UINT16, BASE_DEC,
NULL, 0x0, NULL, HFILL
}
},
{ &hf_data,
{ "Data", "rlogin.data", FT_STRING, BASE_NONE,
NULL, 0x0, NULL, HFILL
}
}
};
static ei_register_info ei[] = {
{ &ei_rlogin_termlen_invalid, { "rlogin.terminal_speed.invalid", PI_MALFORMED, PI_ERROR,
"Terminal length must be a string containing an integer", EXPFILL }}
};
proto_rlogin = proto_register_protocol("Rlogin Protocol", "Rlogin", "rlogin");
proto_register_field_array(proto_rlogin, hf, array_length(hf));
proto_register_subtree_array(ett, array_length(ett));
expert_rlogin = expert_register_protocol(proto_rlogin);
expert_register_field_array(expert_rlogin, ei, array_length(ei));
}
void proto_reg_handoff_rlogin(void)
{
/* Dissector install routine */
dissector_handle_t rlogin_handle = create_dissector_handle(dissect_rlogin,proto_rlogin);
dissector_add_uint_with_preference("tcp.port", RLOGIN_PORT, rlogin_handle);
}
/*
* Editor modelines - http://www.wireshark.org/tools/modelines.html
*
* Local variables:
* c-basic-offset: 8
* tab-width: 8
* indent-tabs-mode: t
* End:
*
* vi: set shiftwidth=8 tabstop=8 noexpandtab:
* :indentSize=8:tabSize=8:noTabs=false:
*/
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