![Guy Harris](/assets/img/avatar_default.png)
simplifies the code (and makes the name in the protocol tree match the name in the dialog box for constructing filter expressions), and also fixes a bug where the item for the request command contained the entire request, not just the request command. svn path=/trunk/; revision=5257
447 lines
12 KiB
C
447 lines
12 KiB
C
/* packet-ftp.c
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* Routines for ftp packet dissection
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* Copyright 1999, Richard Sharpe <rsharpe@ns.aus.com>
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* Copyright 2001, Juan Toledo <toledo@users.sourceforge.net> (Passive FTP)
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*
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* $Id: packet-ftp.c,v 1.43 2002/04/26 20:59:42 guy Exp $
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*
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* Ethereal - Network traffic analyzer
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* By Gerald Combs <gerald@ethereal.com>
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* Copyright 1998 Gerald Combs
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*
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* Copied from packet-pop.c
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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*/
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#ifdef HAVE_CONFIG_H
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# include "config.h"
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#endif
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#include <stdio.h>
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#include <stdlib.h>
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#include <ctype.h>
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#ifdef HAVE_SYS_TYPES_H
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# include <sys/types.h>
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#endif
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#ifdef HAVE_NETINET_IN_H
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# include <netinet/in.h>
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#endif
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#include <string.h>
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#include <glib.h>
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#include <epan/packet.h>
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#include <epan/strutil.h>
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#include <epan/conversation.h>
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static int proto_ftp = -1;
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static int proto_ftp_data = -1;
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static int hf_ftp_response = -1;
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static int hf_ftp_request = -1;
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static int hf_ftp_request_command = -1;
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static int hf_ftp_request_arg = -1;
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static int hf_ftp_response_code = -1;
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static int hf_ftp_response_arg = -1;
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static gint ett_ftp = -1;
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static gint ett_ftp_data = -1;
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static dissector_handle_t ftpdata_handle;
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#define TCP_PORT_FTPDATA 20
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#define TCP_PORT_FTP 21
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static void
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dissect_ftpdata(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree);
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/*
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* Handle a response to a PASV command.
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*
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* We ignore the IP address in the reply, and use the address from which
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* the request came.
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*
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* XXX - are there cases where they differ? What if the FTP server is
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* behind a NAT box, so that the address it puts into the reply isn't
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* the address at which you should contact it? Do all NAT boxes detect
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* FTP PASV replies and rewrite the address? (I suspect not.)
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*
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* RFC 959 doesn't say much about the syntax of the 227 reply.
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*
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* A proposal from Dan Bernstein at
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*
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* http://cr.yp.to/ftp/retr.html
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*
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* "recommend[s] that clients use the following strategy to parse the
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* response line: look for the first digit after the initial space; look
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* for the fourth comma after that digit; read two (possibly negative)
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* integers, separated by a comma; the TCP port number is p1*256+p2, where
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* p1 is the first integer modulo 256 and p2 is the second integer modulo
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* 256."
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*
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* wget 1.5.3 looks for a digit, although it doesn't handle negative
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* integers.
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*
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* The FTP code in the source of the cURL library, at
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*
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* http://curl.haxx.se/lxr/source/lib/ftp.c
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*
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* says that cURL "now scans for a sequence of six comma-separated numbers
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* and will take them as IP+port indicators"; it loops, doing "sscanf"s
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* looking for six numbers separated by commas, stepping the start pointer
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* in the scanf one character at a time - i.e., it tries rather exhaustively.
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*
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* An optimization would be to scan for a digit, and start there, and if
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* the scanf doesn't find six values, scan for the next digit and try
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* again; this will probably succeed on the first try.
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*
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* The cURL code also says that "found reply-strings include":
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*
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* "227 Entering Passive Mode (127,0,0,1,4,51)"
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* "227 Data transfer will passively listen to 127,0,0,1,4,51"
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* "227 Entering passive mode. 127,0,0,1,4,51"
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*
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* so it appears that you can't assume there are parentheses around
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* the address and port number.
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*/
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static void
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handle_pasv_response(const u_char *line, int linelen, packet_info *pinfo)
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{
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char *args;
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char *p;
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u_char c;
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int i;
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int address[4], port[2];
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guint16 server_port;
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conversation_t *conversation;
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/*
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* Copy the rest of the line into a null-terminated buffer.
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*/
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args = g_malloc(linelen + 1);
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memcpy(args, line, linelen);
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args[linelen] = '\0';
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p = args;
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for (;;) {
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/*
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* Look for a digit.
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*/
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while ((c = *p) != '\0' && !isdigit(c))
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p++;
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if (*p == '\0') {
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/*
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* We ran out of text without finding anything.
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*/
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break;
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}
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/*
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* See if we have six numbers.
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*/
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i = sscanf(p, "%d,%d,%d,%d,%d,%d",
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&address[0], &address[1], &address[2], &address[3],
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&port[0], &port[1]);
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if (i == 6) {
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/*
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* We have a winner!
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* Set up a conversation, to be dissected as FTP data.
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*/
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server_port = ((port[0] & 0xFF)<<8) | (port[1] & 0xFF);
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/*
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* XXX - should this call to "find_conversation()"
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* just use "pinfo->src" and "server_port", and
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* wildcard everything else?
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*/
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conversation = find_conversation(&pinfo->src,
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&pinfo->dst, PT_TCP, server_port, 0, NO_PORT_B);
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if (conversation == NULL) {
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/*
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* XXX - should this call to
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* "conversation_new()" just use "pinfo->src"
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* and "server_port", and wildcard everything
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* else?
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*
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* XXX - what if we did find a conversation?
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* As we create it only on the first pass
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* through the packets, if we find one, it's
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* presumably an unrelated conversation.
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* Should we remove the old one from the hash
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* table and put this one in its place?
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* Can the conversaton code handle
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* conversations not in the hash table?
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*/
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conversation = conversation_new(&pinfo->src,
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&pinfo->dst, PT_TCP, server_port, 0,
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NO_PORT2);
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conversation_set_dissector(conversation,
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ftpdata_handle);
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}
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break;
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}
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/*
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* Well, that didn't work. Skip the first number we found,
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* and keep trying.
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*/
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while ((c = *p) != '\0' && isdigit(c))
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p++;
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}
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g_free(args);
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}
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static void
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dissect_ftp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
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{
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gboolean is_request;
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proto_tree *ftp_tree = NULL;
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proto_item *ti;
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gint offset = 0;
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const u_char *line;
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gboolean is_pasv_response = FALSE;
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gint next_offset;
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int linelen;
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int tokenlen;
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const u_char *next_token;
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if (pinfo->match_port == pinfo->destport)
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is_request = TRUE;
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else
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is_request = FALSE;
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if (check_col(pinfo->cinfo, COL_PROTOCOL))
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col_set_str(pinfo->cinfo, COL_PROTOCOL, "FTP");
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/*
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* Find the end of the first line.
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*
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* Note that "tvb_find_line_end()" will return a value that is
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* not longer than what's in the buffer, so the "tvb_get_ptr()"
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* call won't throw an exception.
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*/
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linelen = tvb_find_line_end(tvb, offset, -1, &next_offset);
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line = tvb_get_ptr(tvb, offset, linelen);
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if (check_col(pinfo->cinfo, COL_INFO)) {
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/*
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* Put the first line from the buffer into the summary
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* (but leave out the line terminator).
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*/
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col_add_fstr(pinfo->cinfo, COL_INFO, "%s: %s",
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is_request ? "Request" : "Response",
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format_text(line, linelen));
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}
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if (tree) {
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ti = proto_tree_add_item(tree, proto_ftp, tvb, offset, -1,
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FALSE);
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ftp_tree = proto_item_add_subtree(ti, ett_ftp);
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if (is_request) {
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proto_tree_add_boolean_hidden(ftp_tree,
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hf_ftp_request, tvb, 0, 0, TRUE);
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proto_tree_add_boolean_hidden(ftp_tree,
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hf_ftp_response, tvb, 0, 0, FALSE);
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} else {
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proto_tree_add_boolean_hidden(ftp_tree,
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hf_ftp_request, tvb, 0, 0, FALSE);
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proto_tree_add_boolean_hidden(ftp_tree,
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hf_ftp_response, tvb, 0, 0, TRUE);
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}
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}
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/*
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* Extract the first token, and, if there is a first
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* token, add it as the request or reply code.
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*/
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tokenlen = get_token_len(line, line + linelen, &next_token);
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if (tokenlen != 0) {
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if (is_request) {
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if (tree) {
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proto_tree_add_item(ftp_tree,
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hf_ftp_request_command, tvb, offset,
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tokenlen, FALSE);
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}
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} else {
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/*
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* This is a response; see if it's a passive-mode
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* response.
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*
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* XXX - check for "229" responses to EPSV
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* commands, to handle IPv6, as per RFC 2428?
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*
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* XXX - does anybody do FOOBAR, as per RFC 1639,
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* or has that been supplanted by RFC 2428?
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*/
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if (tokenlen == 3 &&
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strncmp("227", line, tokenlen) == 0)
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is_pasv_response = TRUE;
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if (tree) {
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proto_tree_add_uint(ftp_tree,
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hf_ftp_response_code, tvb, offset,
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tokenlen, atoi(line));
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}
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}
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offset += next_token - line;
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linelen -= next_token - line;
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line = next_token;
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/*
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* If this is a PASV response, handle it if we haven't
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* already processed this frame.
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*/
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if (!pinfo->fd->flags.visited && is_pasv_response) {
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/*
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* We haven't processed this frame, and it contains
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* a PASV response; set up a conversation for the
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* data.
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*/
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handle_pasv_response(line, linelen, pinfo);
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}
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}
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if (tree) {
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/*
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* Add the rest of the first line as request or
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* reply data.
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*/
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if (linelen != 0) {
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if (is_request) {
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proto_tree_add_item(ftp_tree,
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hf_ftp_request_arg, tvb, offset,
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linelen, FALSE);
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} else {
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proto_tree_add_item(ftp_tree,
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hf_ftp_response_arg, tvb, offset,
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linelen, FALSE);
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}
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}
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offset = next_offset;
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/*
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* Show the rest of the request or response as text,
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* a line at a time.
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*/
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while (tvb_offset_exists(tvb, offset)) {
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/*
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* Find the end of the line.
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*/
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linelen = tvb_find_line_end(tvb, offset, -1,
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&next_offset);
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/*
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* Put this line.
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*/
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proto_tree_add_text(ftp_tree, tvb, offset,
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next_offset - offset, "%s",
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tvb_format_text(tvb, offset, next_offset - offset));
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offset = next_offset;
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}
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}
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}
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static void
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dissect_ftpdata(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
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{
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proto_tree *ti, *ftp_data_tree;
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int data_length;
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if (check_col(pinfo->cinfo, COL_PROTOCOL))
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col_set_str(pinfo->cinfo, COL_PROTOCOL, "FTP-DATA");
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if (check_col(pinfo->cinfo, COL_INFO)) {
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col_add_fstr(pinfo->cinfo, COL_INFO, "FTP Data: %u bytes",
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tvb_reported_length(tvb));
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}
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if (tree) {
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data_length = tvb_length(tvb);
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ti = proto_tree_add_item(tree, proto_ftp_data, tvb, 0, -1,
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FALSE);
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ftp_data_tree = proto_item_add_subtree(ti, ett_ftp_data);
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/*
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* XXX - if this is binary data, it'll produce
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* a *really* long line.
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*/
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proto_tree_add_text(ftp_data_tree, tvb, 0, data_length,
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"FTP Data: %s", tvb_format_text(tvb, 0, data_length));
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}
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}
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void
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proto_register_ftp(void)
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{
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static hf_register_info hf[] = {
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{ &hf_ftp_response,
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{ "Response", "ftp.response",
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FT_BOOLEAN, BASE_NONE, NULL, 0x0,
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"TRUE if FTP response", HFILL }},
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{ &hf_ftp_request,
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{ "Request", "ftp.request",
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FT_BOOLEAN, BASE_NONE, NULL, 0x0,
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"TRUE if FTP request", HFILL }},
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{ &hf_ftp_request_command,
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{ "Request command", "ftp.request.command",
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FT_STRING, BASE_NONE, NULL, 0x0,
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"", HFILL }},
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{ &hf_ftp_request_arg,
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{ "Request arg", "ftp.request.arg",
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FT_STRING, BASE_NONE, NULL, 0x0,
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"", HFILL }},
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{ &hf_ftp_response_code,
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{ "Response code", "ftp.response.code",
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FT_UINT8, BASE_DEC, NULL, 0x0,
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"", HFILL }},
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{ &hf_ftp_response_arg,
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{ "Response arg", "ftp.reponse.arg",
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FT_STRING, BASE_NONE, NULL, 0x0,
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"", HFILL }}
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};
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static gint *ett[] = {
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&ett_ftp,
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&ett_ftp_data,
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};
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proto_ftp = proto_register_protocol("File Transfer Protocol (FTP)", "FTP",
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"ftp");
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proto_ftp_data = proto_register_protocol("FTP Data", "FTP-DATA", "ftp-data");
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proto_register_field_array(proto_ftp, hf, array_length(hf));
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proto_register_subtree_array(ett, array_length(ett));
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ftpdata_handle = create_dissector_handle(dissect_ftpdata, proto_ftp_data);
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}
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void
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proto_reg_handoff_ftp(void)
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{
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dissector_handle_t ftpdata_handle, ftp_handle;
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ftpdata_handle = create_dissector_handle(dissect_ftpdata, proto_ftp_data);
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dissector_add("tcp.port", TCP_PORT_FTPDATA, ftpdata_handle);
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ftp_handle = create_dissector_handle(dissect_ftp, proto_ftp);
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dissector_add("tcp.port", TCP_PORT_FTP, ftp_handle);
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}
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