2 * ip_vs_ftp.c: IPVS ftp application module
4 * Version: $Id: ip_vs_ftp.c,v 1.13 2002/09/15 08:14:08 wensong Exp $
6 * Authors: Wensong Zhang <wensong@linuxvirtualserver.org>
11 * This program is free software; you can redistribute it and/or
12 * modify it under the terms of the GNU General Public License
13 * as published by the Free Software Foundation; either version
14 * 2 of the License, or (at your option) any later version.
16 * Most code here is taken from ip_masq_ftp.c in kernel 2.2. The difference
17 * is that ip_vs_ftp module handles the reverse direction to ip_masq_ftp.
19 * IP_MASQ_FTP ftp masquerading module
21 * Version: @(#)ip_masq_ftp.c 0.04 02/05/96
23 * Author: Wouter Gadeyne
27 #include <linux/module.h>
28 #include <linux/moduleparam.h>
29 #include <linux/kernel.h>
30 #include <linux/skbuff.h>
33 #include <net/protocol.h>
36 #include <net/ip_vs.h>
39 #define SERVER_STRING "227 Entering Passive Mode ("
40 #define CLIENT_STRING "PORT "
44 * List of ports (up to IP_VS_APP_MAX_PORTS) to be handled by helper
45 * First port is set to the default port.
47 static int ports
[IP_VS_APP_MAX_PORTS
] = {21, 0};
49 module_param_array(ports
, int, ports_c
, 0);
54 #ifdef CONFIG_IP_VS_DEBUG
56 module_param(debug
, int, 0);
61 static int ip_vs_ftp_pasv
;
65 ip_vs_ftp_init_conn(struct ip_vs_app
*app
, struct ip_vs_conn
*cp
)
72 ip_vs_ftp_done_conn(struct ip_vs_app
*app
, struct ip_vs_conn
*cp
)
79 * Get <addr,port> from the string "xxx.xxx.xxx.xxx,ppp,ppp", started
80 * with the "pattern" and terminated with the "term" character.
81 * <addr,port> is in network order.
83 static int ip_vs_ftp_get_addrport(char *data
, char *data_limit
,
84 const char *pattern
, size_t plen
, char term
,
85 __u32
*addr
, __u16
*port
,
86 char **start
, char **end
)
91 if (data_limit
- data
< plen
) {
92 /* check if there is partial match */
93 if (strnicmp(data
, pattern
, data_limit
- data
) == 0)
99 if (strnicmp(data
, pattern
, plen
) != 0) {
102 *start
= data
+ plen
;
104 for (data
= *start
; *data
!= term
; data
++) {
105 if (data
== data_limit
)
110 memset(p
, 0, sizeof(p
));
111 for (data
= *start
; data
!= *end
; data
++) {
112 if (*data
>= '0' && *data
<= '9') {
113 p
[i
] = p
[i
]*10 + *data
- '0';
114 } else if (*data
== ',' && i
< 5) {
117 /* unexpected character */
125 *addr
= (p
[3]<<24) | (p
[2]<<16) | (p
[1]<<8) | p
[0];
126 *port
= (p
[5]<<8) | p
[4];
132 * Look at outgoing ftp packets to catch the response to a PASV command
133 * from the server (inside-to-outside).
134 * When we see one, we build a connection entry with the client address,
135 * client port 0 (unknown at the moment), the server address and the
136 * server port. Mark the current connection entry as a control channel
137 * of the new entry. All this work is just to make the data connection
138 * can be scheduled to the right server later.
140 * The outgoing packet should be something like
141 * "227 Entering Passive Mode (xxx,xxx,xxx,xxx,ppp,ppp)".
142 * xxx,xxx,xxx,xxx is the server address, ppp,ppp is the server port number.
144 static int ip_vs_ftp_out(struct ip_vs_app
*app
, struct ip_vs_conn
*cp
,
145 struct sk_buff
**pskb
, int *diff
)
149 char *data
, *data_limit
;
153 struct ip_vs_conn
*n_cp
;
154 char buf
[24]; /* xxx.xxx.xxx.xxx,ppp,ppp\000 */
160 /* Only useful for established sessions */
161 if (cp
->state
!= IP_VS_TCP_S_ESTABLISHED
)
164 /* Linear packets are much easier to deal with. */
165 if (!ip_vs_make_skb_writable(pskb
, (*pskb
)->len
))
168 if (cp
->app_data
== &ip_vs_ftp_pasv
) {
169 iph
= (*pskb
)->nh
.iph
;
170 th
= (struct tcphdr
*)&(((char *)iph
)[iph
->ihl
*4]);
171 data
= (char *)th
+ (th
->doff
<< 2);
172 data_limit
= (*pskb
)->tail
;
174 if (ip_vs_ftp_get_addrport(data
, data_limit
,
176 sizeof(SERVER_STRING
)-1, ')',
181 IP_VS_DBG(1-debug
, "PASV response (%u.%u.%u.%u:%d) -> "
182 "%u.%u.%u.%u:%d detected\n",
183 NIPQUAD(from
), ntohs(port
), NIPQUAD(cp
->caddr
), 0);
186 * Now update or create an connection entry for it
188 n_cp
= ip_vs_conn_out_get(iph
->protocol
, from
, port
,
191 n_cp
= ip_vs_conn_new(IPPROTO_TCP
,
195 IP_VS_CONN_F_NO_CPORT
,
200 /* add its controller */
201 ip_vs_control_add(n_cp
, cp
);
205 * Replace the old passive address with the new one
209 sprintf(buf
,"%d,%d,%d,%d,%d,%d", NIPQUAD(from
),
210 port
&255, (port
>>8)&255);
211 buf_len
= strlen(buf
);
214 * Calculate required delta-offset to keep TCP happy
216 *diff
= buf_len
- (end
-start
);
219 /* simply replace it with new passive address */
220 memcpy(start
, buf
, buf_len
);
223 ret
= !ip_vs_skb_replace(*pskb
, GFP_ATOMIC
, start
,
224 end
-start
, buf
, buf_len
);
228 ip_vs_tcp_conn_listen(n_cp
);
229 ip_vs_conn_put(n_cp
);
237 * Look at incoming ftp packets to catch the PASV/PORT command
238 * (outside-to-inside).
240 * The incoming packet having the PORT command should be something like
241 * "PORT xxx,xxx,xxx,xxx,ppp,ppp\n".
242 * xxx,xxx,xxx,xxx is the client address, ppp,ppp is the client port number.
243 * In this case, we create a connection entry using the client address and
244 * port, so that the active ftp data connection from the server can reach
247 static int ip_vs_ftp_in(struct ip_vs_app
*app
, struct ip_vs_conn
*cp
,
248 struct sk_buff
**pskb
, int *diff
)
252 char *data
, *data_start
, *data_limit
;
256 struct ip_vs_conn
*n_cp
;
258 /* no diff required for incoming packets */
261 /* Only useful for established sessions */
262 if (cp
->state
!= IP_VS_TCP_S_ESTABLISHED
)
265 /* Linear packets are much easier to deal with. */
266 if (!ip_vs_make_skb_writable(pskb
, (*pskb
)->len
))
270 * Detecting whether it is passive
272 iph
= (*pskb
)->nh
.iph
;
273 th
= (struct tcphdr
*)&(((char *)iph
)[iph
->ihl
*4]);
275 /* Since there may be OPTIONS in the TCP packet and the HLEN is
276 the length of the header in 32-bit multiples, it is accurate
277 to calculate data address by th+HLEN*4 */
278 data
= data_start
= (char *)th
+ (th
->doff
<< 2);
279 data_limit
= (*pskb
)->tail
;
281 while (data
<= data_limit
- 6) {
282 if (strnicmp(data
, "PASV\r\n", 6) == 0) {
283 /* Passive mode on */
284 IP_VS_DBG(1-debug
, "got PASV at %zd of %zd\n",
286 data_limit
- data_start
);
287 cp
->app_data
= &ip_vs_ftp_pasv
;
294 * To support virtual FTP server, the scenerio is as follows:
295 * FTP client ----> Load Balancer ----> FTP server
296 * First detect the port number in the application data,
297 * then create a new connection entry for the coming data
300 if (ip_vs_ftp_get_addrport(data_start
, data_limit
,
301 CLIENT_STRING
, sizeof(CLIENT_STRING
)-1,
306 IP_VS_DBG(1-debug
, "PORT %u.%u.%u.%u:%d detected\n",
307 NIPQUAD(to
), ntohs(port
));
309 /* Passive mode off */
313 * Now update or create a connection entry for it
315 IP_VS_DBG(1-debug
, "protocol %s %u.%u.%u.%u:%d %u.%u.%u.%u:%d\n",
316 ip_vs_proto_name(iph
->protocol
),
317 NIPQUAD(to
), ntohs(port
), NIPQUAD(cp
->vaddr
), 0);
319 n_cp
= ip_vs_conn_in_get(iph
->protocol
,
321 cp
->vaddr
, htons(ntohs(cp
->vport
)-1));
323 n_cp
= ip_vs_conn_new(IPPROTO_TCP
,
325 cp
->vaddr
, htons(ntohs(cp
->vport
)-1),
326 cp
->daddr
, htons(ntohs(cp
->dport
)-1),
332 /* add its controller */
333 ip_vs_control_add(n_cp
, cp
);
337 * Move tunnel to listen state
339 ip_vs_tcp_conn_listen(n_cp
);
340 ip_vs_conn_put(n_cp
);
346 static struct ip_vs_app ip_vs_ftp
= {
348 .type
= IP_VS_APP_TYPE_FTP
,
349 .protocol
= IPPROTO_TCP
,
350 .module
= THIS_MODULE
,
351 .incs_list
= LIST_HEAD_INIT(ip_vs_ftp
.incs_list
),
352 .init_conn
= ip_vs_ftp_init_conn
,
353 .done_conn
= ip_vs_ftp_done_conn
,
356 .pkt_out
= ip_vs_ftp_out
,
357 .pkt_in
= ip_vs_ftp_in
,
362 * ip_vs_ftp initialization
364 static int __init
ip_vs_ftp_init(void)
367 struct ip_vs_app
*app
= &ip_vs_ftp
;
369 ret
= register_ip_vs_app(app
);
373 for (i
=0; i
<IP_VS_APP_MAX_PORTS
; i
++) {
376 ret
= register_ip_vs_app_inc(app
, app
->protocol
, ports
[i
]);
379 IP_VS_DBG(1-debug
, "%s: loaded support on port[%d] = %d\n",
380 app
->name
, i
, ports
[i
]);
384 unregister_ip_vs_app(app
);
393 static void __exit
ip_vs_ftp_exit(void)
395 unregister_ip_vs_app(&ip_vs_ftp
);
399 module_init(ip_vs_ftp_init
);
400 module_exit(ip_vs_ftp_exit
);
401 MODULE_LICENSE("GPL");