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wireshark/packet-ftp.c

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/* packet-ftp.c
* Routines for ftp packet dissection
* Copyright 1999, Richard Sharpe <rsharpe@ns.aus.com>
* Copyright 2001, Juan Toledo <toledo@users.sourceforge.net> (Passive FTP)
*
* $Id: packet-ftp.c,v 1.54 2003/10/08 11:33:19 jmayer Exp $
*
* Ethereal - Network traffic analyzer
* By Gerald Combs <gerald@ethereal.com>
* Copyright 1998 Gerald Combs
*
* Copied from packet-pop.c
*
* 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/
#ifdef HAVE_CONFIG_H
# include "config.h"
#endif
#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include <string.h>
#include <glib.h>
#include <epan/packet.h>
#include <epan/strutil.h>
#include <epan/conversation.h>
static int proto_ftp = -1;
static int proto_ftp_data = -1;
static int hf_ftp_response = -1;
static int hf_ftp_request = -1;
static int hf_ftp_request_command = -1;
static int hf_ftp_request_arg = -1;
static int hf_ftp_response_code = -1;
static int hf_ftp_response_arg = -1;
static int hf_ftp_pasv_ip = -1 ;
static int hf_ftp_pasv_port = -1;
static int hf_ftp_pasv_nat = -1;
static int hf_ftp_active_ip = -1;
static int hf_ftp_active_port = -1;
static int hf_ftp_active_nat = -1;
static gint ett_ftp = -1;
static gint ett_ftp_reqresp = -1;
static gint ett_ftp_data = -1;
static dissector_handle_t ftpdata_handle;
#define TCP_PORT_FTPDATA 20
#define TCP_PORT_FTP 21
static const value_string response_table[] = {
{ 110, "Restart marker reply" },
{ 120, "Service ready in nnn minutes" },
{ 125, "Data connection already open; transfer starting" },
{ 150, "File status okay; about to open data connection" },
{ 200, "Command okay" },
{ 202, "Command not implemented, superfluous at this site" },
{ 211, "System status, or system help reply" },
{ 212, "Directory status" },
{ 213, "File status" },
{ 214, "Help message" },
{ 215, "NAME system type" },
{ 220, "Service ready for new user" },
{ 221, "Service closing control connection" },
{ 225, "Data connection open; no transfer in progress" },
{ 226, "Closing data connection" },
{ 227, "Entering Passive Mode" },
{ 230, "User logged in, proceed" },
{ 250, "Requested file action okay, completed" },
{ 257, "PATHNAME created" },
{ 331, "User name okay, need password" },
{ 332, "Need account for login" },
{ 350, "Requested file action pending further information" },
{ 421, "Service not available, closing control connection" },
{ 425, "Can't open data connection" },
{ 426, "Connection closed; transfer aborted" },
{ 450, "Requested file action not taken" },
{ 451, "Requested action aborted: local error in processing" },
{ 452, "Requested action not taken. Insufficient storage space in system" },
{ 500, "Syntax error, command unrecognized" },
{ 501, "Syntax error in parameters or arguments" },
{ 502, "Command not implemented" },
{ 503, "Bad sequence of commands" },
{ 504, "Command not implemented for that parameter" },
{ 530, "Not logged in" },
{ 532, "Need account for storing files" },
{ 550, "Requested action not taken: File unavailable" },
{ 551, "Requested action aborted: page type unknown" },
{ 552, "Requested file action aborted: Exceeded storage allocation" },
{ 553, "Requested action not taken: File name not allowed" },
{ 0, NULL }
};
static void
dissect_ftpdata(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree);
/*
* Parse the address and port information in a PORT command or in the
* response to a PASV command. Return TRUE if we found an address and
* port, and supply the address and port; return FALSE if we didn't find
* them.
*
* We ignore the IP address in the reply, and use the address from which
* the request came.
*
* XXX - are there cases where they differ? What if the FTP server is
* behind a NAT box, so that the address it puts into the reply isn't
* the address at which you should contact it? Do all NAT boxes detect
* FTP PASV replies and rewrite the address? (I suspect not.)
*
* RFC 959 doesn't say much about the syntax of the 227 reply.
*
* A proposal from Dan Bernstein at
*
* http://cr.yp.to/ftp/retr.html
*
* "recommend[s] that clients use the following strategy to parse the
* response line: look for the first digit after the initial space; look
* for the fourth comma after that digit; read two (possibly negative)
* integers, separated by a comma; the TCP port number is p1*256+p2, where
* p1 is the first integer modulo 256 and p2 is the second integer modulo
* 256."
*
* wget 1.5.3 looks for a digit, although it doesn't handle negative
* integers.
*
* The FTP code in the source of the cURL library, at
*
* http://curl.haxx.se/lxr/source/lib/ftp.c
*
* says that cURL "now scans for a sequence of six comma-separated numbers
* and will take them as IP+port indicators"; it loops, doing "sscanf"s
* looking for six numbers separated by commas, stepping the start pointer
* in the scanf one character at a time - i.e., it tries rather exhaustively.
*
* An optimization would be to scan for a digit, and start there, and if
* the scanf doesn't find six values, scan for the next digit and try
* again; this will probably succeed on the first try.
*
* The cURL code also says that "found reply-strings include":
*
* "227 Entering Passive Mode (127,0,0,1,4,51)"
* "227 Data transfer will passively listen to 127,0,0,1,4,51"
* "227 Entering passive mode. 127,0,0,1,4,51"
*
* so it appears that you can't assume there are parentheses around
* the address and port number.
*/
static gboolean
parse_port_pasv(const guchar *line, int linelen, guint32 *ftp_ip,
guint16 *ftp_port)
{
char *args;
char *p;
guchar c;
int i;
int address[4], port[2];
gboolean ret = FALSE;
/*
* Copy the rest of the line into a null-terminated buffer.
*/
args = g_malloc(linelen + 1);
memcpy(args, line, linelen);
args[linelen] = '\0';
p = args;
for (;;) {
/*
* Look for a digit.
*/
while ((c = *p) != '\0' && !isdigit(c))
p++;
if (*p == '\0') {
/*
* We ran out of text without finding anything.
*/
break;
}
/*
* See if we have six numbers.
*/
i = sscanf(p, "%d,%d,%d,%d,%d,%d",
&address[0], &address[1], &address[2], &address[3],
&port[0], &port[1]);
if (i == 6) {
/*
* We have a winner!
*/
*ftp_port = ((port[0] & 0xFF)<<8) | (port[1] & 0xFF);
*ftp_ip = g_htonl((address[0] << 24) | (address[1] <<16) | (address[2] <<8) | address[3]);
ret = TRUE;
break;
}
/*
* Well, that didn't work. Skip the first number we found,
* and keep trying.
*/
while ((c = *p) != '\0' && isdigit(c))
p++;
}
g_free(args);
return ret;
}
static void
dissect_ftp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
{
gboolean is_request;
proto_tree *ftp_tree = NULL;
proto_tree *reqresp_tree = NULL;
proto_item *ti;
gint offset = 0;
const guchar *line;
guint32 code;
gchar code_str[4];
gboolean is_port_request = FALSE;
gboolean is_pasv_response = FALSE;
gint next_offset;
int linelen;
int tokenlen;
const guchar *next_token;
guint32 pasv_ip;
guint32 ftp_ip;
guint16 ftp_port;
address ftp_ip_address;
gboolean ftp_nat;
conversation_t *conversation;
ftp_ip_address = pinfo->src;
if (pinfo->match_port == pinfo->destport)
is_request = TRUE;
else
is_request = FALSE;
if (check_col(pinfo->cinfo, COL_PROTOCOL))
col_set_str(pinfo->cinfo, COL_PROTOCOL, "FTP");
/*
* Find the end of the first line.
*
* Note that "tvb_find_line_end()" will return a value that is
* not longer than what's in the buffer, so the "tvb_get_ptr()"
* call won't throw an exception.
*/
linelen = tvb_find_line_end(tvb, offset, -1, &next_offset, FALSE);
line = tvb_get_ptr(tvb, offset, linelen);
if (check_col(pinfo->cinfo, COL_INFO)) {
/*
* Put the first line from the buffer into the summary
* (but leave out the line terminator).
*/
col_add_fstr(pinfo->cinfo, COL_INFO, "%s: %s",
is_request ? "Request" : "Response",
format_text(line, linelen));
}
if (tree) {
ti = proto_tree_add_item(tree, proto_ftp, tvb, offset, -1,
FALSE);
ftp_tree = proto_item_add_subtree(ti, ett_ftp);
if (is_request) {
proto_tree_add_boolean_hidden(ftp_tree,
hf_ftp_request, tvb, 0, 0, TRUE);
proto_tree_add_boolean_hidden(ftp_tree,
hf_ftp_response, tvb, 0, 0, FALSE);
} else {
proto_tree_add_boolean_hidden(ftp_tree,
hf_ftp_request, tvb, 0, 0, FALSE);
proto_tree_add_boolean_hidden(ftp_tree,
hf_ftp_response, tvb, 0, 0, TRUE);
}
/*
* Put the line into the protocol tree.
*/
ti = proto_tree_add_text(ftp_tree, tvb, offset,
next_offset - offset, "%s",
tvb_format_text(tvb, offset, next_offset - offset));
reqresp_tree = proto_item_add_subtree(ti, ett_ftp_reqresp);
}
if (is_request) {
/*
* Extract the first token, and, if there is a first
* token, add it as the request.
*/
tokenlen = get_token_len(line, line + linelen, &next_token);
if (tokenlen != 0) {
if (tree) {
proto_tree_add_item(reqresp_tree,
hf_ftp_request_command, tvb, offset,
tokenlen, FALSE);
}
if (strncmp(line, "PORT", tokenlen) == 0)
is_port_request = TRUE;
}
} else {
/*
* This is a response; the response code is 3 digits,
* followed by a space or hyphen, possibly followed by
* text.
*
* If the line doesn't start with 3 digits, it's part of
* a continuation.
*
* XXX - keep track of state in the first pass, and
* treat non-continuation lines not beginning with digits
* as errors?
*/
if (linelen >= 3 && isdigit(line[0]) && isdigit(line[1])
&& isdigit(line[2])) {
/*
* One-line reply, or first or last line
* of a multi-line reply.
*/
tvb_get_nstringz0(tvb, offset, sizeof(code_str), code_str);
code = strtoul(code_str, NULL, 10);
if (tree) {
proto_tree_add_uint(reqresp_tree,
hf_ftp_response_code, tvb, offset, 3, code);
}
/*
* See if it's a passive-mode response.
*
* XXX - check for "229" responses to EPSV
* commands, to handle IPv6, as per RFC 2428?
*
* XXX - does anybody do FOOBAR, as per RFC
* 1639, or has that been supplanted by RFC 2428?
*/
if (code == 227)
is_pasv_response = TRUE;
/*
* Skip the 3 digits and, if present, the
* space or hyphen.
*/
if (linelen >= 4)
next_token = line + 4;
else
next_token = line + linelen;
} else {
/*
* Line doesn't start with 3 digits; assume it's
* a line in the middle of a multi-line reply.
*/
next_token = line;
}
}
offset += next_token - line;
linelen -= next_token - line;
line = next_token;
if (tree) {
/*
* Add the rest of the first line as request or
* reply data.
*/
if (linelen != 0) {
if (is_request) {
proto_tree_add_item(reqresp_tree,
hf_ftp_request_arg, tvb, offset,
linelen, FALSE);
} else {
proto_tree_add_item(reqresp_tree,
hf_ftp_response_arg, tvb, offset,
linelen, FALSE);
}
}
offset = next_offset;
}
/*
* If this is a PORT request or a PASV response, handle it.
*/
if (is_port_request) {
if (parse_port_pasv(line, linelen, &ftp_ip,
&ftp_port)) {
if (tree) {
proto_tree_add_ipv4(reqresp_tree,
hf_ftp_active_ip, tvb, 0, 0,
ftp_ip);
proto_tree_add_uint(reqresp_tree,
hf_ftp_active_port, tvb, 0, 0,
ftp_port);
}
SET_ADDRESS(&ftp_ip_address, AT_IPv4, 4,
(const guint8 *)&ftp_ip);
ftp_nat = !ADDRESSES_EQUAL(&pinfo->src,
&ftp_ip_address);
if (ftp_nat) {
if (tree) {
proto_tree_add_boolean(
reqresp_tree,
hf_ftp_active_nat, tvb,
0, 0, ftp_nat);
}
}
}
}
if (is_pasv_response) {
if (linelen != 0) {
/*
* This frame contains a PASV response; set up a
* conversation for the data.
*/
if (parse_port_pasv(line, linelen, &pasv_ip,
&ftp_port)) {
if (tree) {
proto_tree_add_ipv4(reqresp_tree,
hf_ftp_pasv_ip, tvb, 0, 0, pasv_ip);
proto_tree_add_uint(reqresp_tree,
hf_ftp_pasv_port, tvb, 0, 0,
ftp_port);
}
SET_ADDRESS(&ftp_ip_address, AT_IPv4, 4,
(const guint8 *)&pasv_ip);
ftp_nat = !ADDRESSES_EQUAL(&pinfo->src,
&ftp_ip_address);
if (ftp_nat) {
if (tree) {
proto_tree_add_boolean(reqresp_tree,
hf_ftp_pasv_nat, tvb, 0, 0,
ftp_nat);
}
}
/*
* We use "ftp_ip_address", so that if
* we're NAT'd we look for the un-NAT'd
* connection.
*
* XXX - should this call to
* "find_conversation()" just use
* "ftp_ip_address" and "server_port", and
* wildcard everything else?
*/
conversation = find_conversation(&ftp_ip_address,
&pinfo->dst, PT_TCP, ftp_port, 0,
NO_PORT_B);
if (conversation == NULL) {
/*
* XXX - should this call to
* "conversation_new()" just use
* "ftp_ip_address" and "server_port",
* and wildcard everything else?
*
* XXX - what if we did find a
* conversation? As we create it
* only on the first pass through
* the packets, if we find one, it's
* presumably an unrelated conversation.
* Should we remove the old one from
* the hash table and put this one in
* its place? Can the conversation
* code handle conversations not in
* the hash table? Or should we
* make conversations support
* start and end frames, as circuits
* do, and treat this as an indication
* that one conversation was closed
* and a new one was opened?
*/
conversation = conversation_new(
&ftp_ip_address, &pinfo->dst,
PT_TCP, ftp_port, 0, NO_PORT2);
conversation_set_dissector(conversation,
ftpdata_handle);
}
}
}
}
if (tree) {
/*
* Show the rest of the request or response as text,
* a line at a time.
* XXX - only if there's a continuation indicator?
*/
while (tvb_offset_exists(tvb, offset)) {
/*
* Find the end of the line.
*/
linelen = tvb_find_line_end(tvb, offset, -1,
&next_offset, FALSE);
/*
* Put this line.
*/
proto_tree_add_text(ftp_tree, tvb, offset,
next_offset - offset, "%s",
tvb_format_text(tvb, offset, next_offset - offset));
offset = next_offset;
}
}
}
static void
dissect_ftpdata(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
{
proto_tree *ti, *ftp_data_tree;
int data_length;
if (check_col(pinfo->cinfo, COL_PROTOCOL))
col_set_str(pinfo->cinfo, COL_PROTOCOL, "FTP-DATA");
if (check_col(pinfo->cinfo, COL_INFO)) {
col_add_fstr(pinfo->cinfo, COL_INFO, "FTP Data: %u bytes",
tvb_reported_length(tvb));
}
if (tree) {
data_length = tvb_length(tvb);
ti = proto_tree_add_item(tree, proto_ftp_data, tvb, 0, -1,
FALSE);
ftp_data_tree = proto_item_add_subtree(ti, ett_ftp_data);
/*
* XXX - if this is binary data, it'll produce
* a *really* long line.
*/
proto_tree_add_text(ftp_data_tree, tvb, 0, data_length,
"FTP Data: %s", tvb_format_text(tvb, 0, data_length));
}
}
void
proto_register_ftp(void)
{
static hf_register_info hf[] = {
{ &hf_ftp_response,
{ "Response", "ftp.response",
FT_BOOLEAN, BASE_NONE, NULL, 0x0,
"TRUE if FTP response", HFILL }},
{ &hf_ftp_request,
{ "Request", "ftp.request",
FT_BOOLEAN, BASE_NONE, NULL, 0x0,
"TRUE if FTP request", HFILL }},
{ &hf_ftp_request_command,
{ "Request command", "ftp.request.command",
FT_STRING, BASE_NONE, NULL, 0x0,
"", HFILL }},
{ &hf_ftp_request_arg,
{ "Request arg", "ftp.request.arg",
FT_STRING, BASE_NONE, NULL, 0x0,
"", HFILL }},
{ &hf_ftp_response_code,
{ "Response code", "ftp.response.code",
FT_UINT32, BASE_DEC, VALS(response_table), 0x0,
"", HFILL }},
{ &hf_ftp_response_arg,
{ "Response arg", "ftp.response.arg",
FT_STRING, BASE_NONE, NULL, 0x0,
"", HFILL }},
{ &hf_ftp_pasv_ip,
{ "Passive IP address", "ftp.passive.ip",
FT_IPv4, BASE_NONE, NULL,0x0,
"Passive IP address (check NAT)", HFILL}},
{ &hf_ftp_pasv_port,
{ "Passive port", "ftp.passive.port",
FT_UINT16, BASE_DEC, NULL,0x0,
"Passive FTP server port", HFILL }},
{ &hf_ftp_pasv_nat,
{"Passive IP NAT", "ftp.passive.nat",
FT_BOOLEAN, BASE_NONE, NULL, 0x0,
"NAT is active SIP and passive IP different", HFILL }},
{ &hf_ftp_active_ip,
{ "Active IP address", "ftp.active.cip",
FT_IPv4, BASE_NONE, NULL, 0x0,
"Active FTP client IP address", HFILL }},
{ &hf_ftp_active_port,
{"Active port", "ftp.active.port",
FT_UINT16, BASE_DEC, NULL, 0x0,
"Active FTP client port", HFILL }},
{ &hf_ftp_active_nat,
{ "Active IP NAT", "ftp.active.nat",
FT_BOOLEAN, BASE_NONE, NULL, 0x0,
"NAT is active", HFILL}}
};
static gint *ett[] = {
&ett_ftp,
&ett_ftp_reqresp,
&ett_ftp_data,
};
proto_ftp = proto_register_protocol("File Transfer Protocol (FTP)", "FTP",
"ftp");
proto_ftp_data = proto_register_protocol("FTP Data", "FTP-DATA", "ftp-data");
proto_register_field_array(proto_ftp, hf, array_length(hf));
proto_register_subtree_array(ett, array_length(ett));
ftpdata_handle = create_dissector_handle(dissect_ftpdata, proto_ftp_data);
}
void
proto_reg_handoff_ftp(void)
{
dissector_handle_t ftpdata_handle, ftp_handle;
ftpdata_handle = create_dissector_handle(dissect_ftpdata, proto_ftp_data);
dissector_add("tcp.port", TCP_PORT_FTPDATA, ftpdata_handle);
ftp_handle = create_dissector_handle(dissect_ftp, proto_ftp);
dissector_add("tcp.port", TCP_PORT_FTP, ftp_handle);
}
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