diff options
Diffstat (limited to 'lib/libalias/alias_ftp.c')
| -rw-r--r-- | lib/libalias/alias_ftp.c | 675 |
1 files changed, 0 insertions, 675 deletions
diff --git a/lib/libalias/alias_ftp.c b/lib/libalias/alias_ftp.c deleted file mode 100644 index b628528..0000000 --- a/lib/libalias/alias_ftp.c +++ /dev/null @@ -1,675 +0,0 @@ -/*- - * Copyright (c) 2001 Charles Mott <cm@linktel.net> - * All rights reserved. - * - * Redistribution and use in source and binary forms, with or without - * modification, are permitted provided that the following conditions - * are met: - * 1. Redistributions of source code must retain the above copyright - * notice, this list of conditions and the following disclaimer. - * 2. Redistributions in binary form must reproduce the above copyright - * notice, this list of conditions and the following disclaimer in the - * documentation and/or other materials provided with the distribution. - * - * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND - * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE - * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE - * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE - * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL - * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS - * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) - * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT - * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY - * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF - * SUCH DAMAGE. - */ - -#include <sys/cdefs.h> -__FBSDID("$FreeBSD$"); - -/* - Alias_ftp.c performs special processing for FTP sessions under - TCP. Specifically, when a PORT/EPRT command from the client - side or 227/229 reply from the server is sent, it is intercepted - and modified. The address is changed to the gateway machine - and an aliasing port is used. - - For this routine to work, the message must fit entirely into a - single TCP packet. This is typically the case, but exceptions - can easily be envisioned under the actual specifications. - - Probably the most troubling aspect of the approach taken here is - that the new message will typically be a different length, and - this causes a certain amount of bookkeeping to keep track of the - changes of sequence and acknowledgment numbers, since the client - machine is totally unaware of the modification to the TCP stream. - - - References: RFC 959, RFC 2428. - - Initial version: August, 1996 (cjm) - - Version 1.6 - Brian Somers and Martin Renters identified an IP checksum - error for modified IP packets. - - Version 1.7: January 9, 1996 (cjm) - Differential checksum computation for change - in IP packet length. - - Version 2.1: May, 1997 (cjm) - Very minor changes to conform with - local/global/function naming conventions - within the packet aliasing module. - - Version 3.1: May, 2000 (eds) - Add support for passive mode, alias the 227 replies. - - See HISTORY file for record of revisions. -*/ - -/* Includes */ -#include <ctype.h> -#include <stdio.h> -#include <string.h> -#include <sys/types.h> -#include <netinet/in_systm.h> -#include <netinet/in.h> -#include <netinet/ip.h> -#include <netinet/tcp.h> - -#include "alias_local.h" - -#define FTP_CONTROL_PORT_NUMBER 21 -#define MAX_MESSAGE_SIZE 128 - -/* FTP protocol flags. */ -#define WAIT_CRLF 0x01 - -enum ftp_message_type { - FTP_PORT_COMMAND, - FTP_EPRT_COMMAND, - FTP_227_REPLY, - FTP_229_REPLY, - FTP_UNKNOWN_MESSAGE -}; - -static int ParseFtpPortCommand(struct libalias *la, char *, int); -static int ParseFtpEprtCommand(struct libalias *la, char *, int); -static int ParseFtp227Reply(struct libalias *la, char *, int); -static int ParseFtp229Reply(struct libalias *la, char *, int); -static void NewFtpMessage(struct libalias *la, struct ip *, struct alias_link *, int, int); - -void -AliasHandleFtpOut( - struct libalias *la, - struct ip *pip, /* IP packet to examine/patch */ - struct alias_link *lnk, /* The link to go through (aliased port) */ - int maxpacketsize /* The maximum size this packet can grow to - (including headers) */ ) -{ - int hlen, tlen, dlen, pflags; - char *sptr; - struct tcphdr *tc; - int ftp_message_type; - -/* Calculate data length of TCP packet */ - tc = (struct tcphdr *)ip_next(pip); - hlen = (pip->ip_hl + tc->th_off) << 2; - tlen = ntohs(pip->ip_len); - dlen = tlen - hlen; - -/* Place string pointer and beginning of data */ - sptr = (char *)pip; - sptr += hlen; - -/* - * Check that data length is not too long and previous message was - * properly terminated with CRLF. - */ - pflags = GetProtocolFlags(lnk); - if (dlen <= MAX_MESSAGE_SIZE && !(pflags & WAIT_CRLF)) { - ftp_message_type = FTP_UNKNOWN_MESSAGE; - - if (ntohs(tc->th_dport) == FTP_CONTROL_PORT_NUMBER) { -/* - * When aliasing a client, check for the PORT/EPRT command. - */ - if (ParseFtpPortCommand(la, sptr, dlen)) - ftp_message_type = FTP_PORT_COMMAND; - else if (ParseFtpEprtCommand(la, sptr, dlen)) - ftp_message_type = FTP_EPRT_COMMAND; - } else { -/* - * When aliasing a server, check for the 227/229 reply. - */ - if (ParseFtp227Reply(la, sptr, dlen)) - ftp_message_type = FTP_227_REPLY; - else if (ParseFtp229Reply(la, sptr, dlen)) { - ftp_message_type = FTP_229_REPLY; - la->true_addr.s_addr = pip->ip_src.s_addr; - } - } - - if (ftp_message_type != FTP_UNKNOWN_MESSAGE) - NewFtpMessage(la, pip, lnk, maxpacketsize, ftp_message_type); - } -/* Track the msgs which are CRLF term'd for PORT/PASV FW breach */ - - if (dlen) { /* only if there's data */ - sptr = (char *)pip; /* start over at beginning */ - tlen = ntohs(pip->ip_len); /* recalc tlen, pkt may - * have grown */ - if (sptr[tlen - 2] == '\r' && sptr[tlen - 1] == '\n') - pflags &= ~WAIT_CRLF; - else - pflags |= WAIT_CRLF; - SetProtocolFlags(lnk, pflags); - } -} - -static int -ParseFtpPortCommand(struct libalias *la, char *sptr, int dlen) -{ - char ch; - int i, state; - u_int32_t addr; - u_short port; - u_int8_t octet; - - /* Format: "PORT A,D,D,R,PO,RT". */ - - /* Return if data length is too short. */ - if (dlen < 18) - return (0); - - addr = port = octet = 0; - state = -4; - for (i = 0; i < dlen; i++) { - ch = sptr[i]; - switch (state) { - case -4: - if (ch == 'P') - state++; - else - return (0); - break; - case -3: - if (ch == 'O') - state++; - else - return (0); - break; - case -2: - if (ch == 'R') - state++; - else - return (0); - break; - case -1: - if (ch == 'T') - state++; - else - return (0); - break; - - case 0: - if (isspace(ch)) - break; - else - state++; - case 1: - case 3: - case 5: - case 7: - case 9: - case 11: - if (isdigit(ch)) { - octet = ch - '0'; - state++; - } else - return (0); - break; - case 2: - case 4: - case 6: - case 8: - if (isdigit(ch)) - octet = 10 * octet + ch - '0'; - else if (ch == ',') { - addr = (addr << 8) + octet; - state++; - } else - return (0); - break; - case 10: - case 12: - if (isdigit(ch)) - octet = 10 * octet + ch - '0'; - else if (ch == ',' || state == 12) { - port = (port << 8) + octet; - state++; - } else - return (0); - break; - } - } - - if (state == 13) { - la->true_addr.s_addr = htonl(addr); - la->true_port = port; - return (1); - } else - return (0); -} - -static int -ParseFtpEprtCommand(struct libalias *la, char *sptr, int dlen) -{ - char ch, delim; - int i, state; - u_int32_t addr; - u_short port; - u_int8_t octet; - - /* Format: "EPRT |1|A.D.D.R|PORT|". */ - - /* Return if data length is too short. */ - if (dlen < 18) - return (0); - - addr = port = octet = 0; - delim = '|'; /* XXX gcc -Wuninitialized */ - state = -4; - for (i = 0; i < dlen; i++) { - ch = sptr[i]; - switch (state) { - case -4: - if (ch == 'E') - state++; - else - return (0); - break; - case -3: - if (ch == 'P') - state++; - else - return (0); - break; - case -2: - if (ch == 'R') - state++; - else - return (0); - break; - case -1: - if (ch == 'T') - state++; - else - return (0); - break; - - case 0: - if (!isspace(ch)) { - delim = ch; - state++; - } - break; - case 1: - if (ch == '1') /* IPv4 address */ - state++; - else - return (0); - break; - case 2: - if (ch == delim) - state++; - else - return (0); - break; - case 3: - case 5: - case 7: - case 9: - if (isdigit(ch)) { - octet = ch - '0'; - state++; - } else - return (0); - break; - case 4: - case 6: - case 8: - case 10: - if (isdigit(ch)) - octet = 10 * octet + ch - '0'; - else if (ch == '.' || state == 10) { - addr = (addr << 8) + octet; - state++; - } else - return (0); - break; - case 11: - if (isdigit(ch)) { - port = ch - '0'; - state++; - } else - return (0); - break; - case 12: - if (isdigit(ch)) - port = 10 * port + ch - '0'; - else if (ch == delim) - state++; - else - return (0); - break; - } - } - - if (state == 13) { - la->true_addr.s_addr = htonl(addr); - la->true_port = port; - return (1); - } else - return (0); -} - -static int -ParseFtp227Reply(struct libalias *la, char *sptr, int dlen) -{ - char ch; - int i, state; - u_int32_t addr; - u_short port; - u_int8_t octet; - - /* Format: "227 Entering Passive Mode (A,D,D,R,PO,RT)" */ - - /* Return if data length is too short. */ - if (dlen < 17) - return (0); - - addr = port = octet = 0; - - state = -3; - for (i = 0; i < dlen; i++) { - ch = sptr[i]; - switch (state) { - case -3: - if (ch == '2') - state++; - else - return (0); - break; - case -2: - if (ch == '2') - state++; - else - return (0); - break; - case -1: - if (ch == '7') - state++; - else - return (0); - break; - - case 0: - if (ch == '(') - state++; - break; - case 1: - case 3: - case 5: - case 7: - case 9: - case 11: - if (isdigit(ch)) { - octet = ch - '0'; - state++; - } else - return (0); - break; - case 2: - case 4: - case 6: - case 8: - if (isdigit(ch)) - octet = 10 * octet + ch - '0'; - else if (ch == ',') { - addr = (addr << 8) + octet; - state++; - } else - return (0); - break; - case 10: - case 12: - if (isdigit(ch)) - octet = 10 * octet + ch - '0'; - else if (ch == ',' || (state == 12 && ch == ')')) { - port = (port << 8) + octet; - state++; - } else - return (0); - break; - } - } - - if (state == 13) { - la->true_port = port; - la->true_addr.s_addr = htonl(addr); - return (1); - } else - return (0); -} - -static int -ParseFtp229Reply(struct libalias *la, char *sptr, int dlen) -{ - char ch, delim; - int i, state; - u_short port; - - /* Format: "229 Entering Extended Passive Mode (|||PORT|)" */ - - /* Return if data length is too short. */ - if (dlen < 11) - return (0); - - port = 0; - delim = '|'; /* XXX gcc -Wuninitialized */ - - state = -3; - for (i = 0; i < dlen; i++) { - ch = sptr[i]; - switch (state) { - case -3: - if (ch == '2') - state++; - else - return (0); - break; - case -2: - if (ch == '2') - state++; - else - return (0); - break; - case -1: - if (ch == '9') - state++; - else - return (0); - break; - - case 0: - if (ch == '(') - state++; - break; - case 1: - delim = ch; - state++; - break; - case 2: - case 3: - if (ch == delim) - state++; - else - return (0); - break; - case 4: - if (isdigit(ch)) { - port = ch - '0'; - state++; - } else - return (0); - break; - case 5: - if (isdigit(ch)) - port = 10 * port + ch - '0'; - else if (ch == delim) - state++; - else - return (0); - break; - case 6: - if (ch == ')') - state++; - else - return (0); - break; - } - } - - if (state == 7) { - la->true_port = port; - return (1); - } else - return (0); -} - -static void -NewFtpMessage(struct libalias *la, struct ip *pip, - struct alias_link *lnk, - int maxpacketsize, - int ftp_message_type) -{ - struct alias_link *ftp_lnk; - -/* Security checks. */ - if (pip->ip_src.s_addr != la->true_addr.s_addr) - return; - - if (la->true_port < IPPORT_RESERVED) - return; - -/* Establish link to address and port found in FTP control message. */ - ftp_lnk = FindUdpTcpOut(la, la->true_addr, GetDestAddress(lnk), - htons(la->true_port), 0, IPPROTO_TCP, 1); - - if (ftp_lnk != NULL) { - int slen, hlen, tlen, dlen; - struct tcphdr *tc; - -#ifndef NO_FW_PUNCH - /* Punch hole in firewall */ - PunchFWHole(ftp_lnk); -#endif - -/* Calculate data length of TCP packet */ - tc = (struct tcphdr *)ip_next(pip); - hlen = (pip->ip_hl + tc->th_off) << 2; - tlen = ntohs(pip->ip_len); - dlen = tlen - hlen; - -/* Create new FTP message. */ - { - char stemp[MAX_MESSAGE_SIZE + 1]; - char *sptr; - u_short alias_port; - u_char *ptr; - int a1, a2, a3, a4, p1, p2; - struct in_addr alias_address; - -/* Decompose alias address into quad format */ - alias_address = GetAliasAddress(lnk); - ptr = (u_char *) & alias_address.s_addr; - a1 = *ptr++; - a2 = *ptr++; - a3 = *ptr++; - a4 = *ptr; - - alias_port = GetAliasPort(ftp_lnk); - - switch (ftp_message_type) { - case FTP_PORT_COMMAND: - case FTP_227_REPLY: - /* Decompose alias port into pair format. */ - ptr = (char *)&alias_port; - p1 = *ptr++; - p2 = *ptr; - - if (ftp_message_type == FTP_PORT_COMMAND) { - /* Generate PORT command string. */ - sprintf(stemp, "PORT %d,%d,%d,%d,%d,%d\r\n", - a1, a2, a3, a4, p1, p2); - } else { - /* Generate 227 reply string. */ - sprintf(stemp, - "227 Entering Passive Mode (%d,%d,%d,%d,%d,%d)\r\n", - a1, a2, a3, a4, p1, p2); - } - break; - case FTP_EPRT_COMMAND: - /* Generate EPRT command string. */ - sprintf(stemp, "EPRT |1|%d.%d.%d.%d|%d|\r\n", - a1, a2, a3, a4, ntohs(alias_port)); - break; - case FTP_229_REPLY: - /* Generate 229 reply string. */ - sprintf(stemp, "229 Entering Extended Passive Mode (|||%d|)\r\n", - ntohs(alias_port)); - break; - } - -/* Save string length for IP header modification */ - slen = strlen(stemp); - -/* Copy modified buffer into IP packet. */ - sptr = (char *)pip; - sptr += hlen; - strncpy(sptr, stemp, maxpacketsize - hlen); - } - -/* Save information regarding modified seq and ack numbers */ - { - int delta; - - SetAckModified(lnk); - delta = GetDeltaSeqOut(pip, lnk); - AddSeq(pip, lnk, delta + slen - dlen); - } - -/* Revise IP header */ - { - u_short new_len; - - new_len = htons(hlen + slen); - DifferentialChecksum(&pip->ip_sum, - &new_len, - &pip->ip_len, - 1); - pip->ip_len = new_len; - } - -/* Compute TCP checksum for revised packet */ - tc->th_sum = 0; - tc->th_sum = TcpChecksum(pip); - } else { -#ifdef DEBUG - fprintf(stderr, - "PacketAlias/HandleFtpOut: Cannot allocate FTP data port\n"); -#endif - } -} |
