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/config.h>
28 #include <linux/module.h>
29 #include <asm/system.h>
30 #include <linux/types.h>
31 #include <linux/kernel.h>
32 #include <linux/skbuff.h>
35 #include <linux/init.h>
36 #include <net/protocol.h>
39 #include <net/ip_vs.h>
42 #define SERVER_STRING "227 Entering Passive Mode ("
43 #define CLIENT_STRING "PORT "
47 * List of ports (up to IP_VS_APP_MAX_PORTS) to be handled by helper
48 * First port is set to the default port.
50 static int ports[IP_VS_APP_MAX_PORTS] = {21, 0};
55 #ifdef CONFIG_IP_VS_DEBUG
57 MODULE_PARM(debug, "i");
60 MODULE_PARM(ports, "1-" __MODULE_STRING(IP_VS_APP_MAX_PORTS) "i");
63 static int ip_vs_ftp_pasv;
67 ip_vs_ftp_init_conn(struct ip_vs_app *app, struct ip_vs_conn *cp)
74 ip_vs_ftp_done_conn(struct ip_vs_app *app, struct ip_vs_conn *cp)
81 * Get <addr,port> from the string "xxx.xxx.xxx.xxx,ppp,ppp", started
82 * with the "pattern" and terminated with the "term" character.
83 * <addr,port> is in network order.
85 static int ip_vs_ftp_get_addrport(char *data, char *data_limit,
86 const char *pattern, size_t plen, char term,
87 __u32 *addr, __u16 *port,
88 char **start, char **end)
93 if (data_limit - data < plen) {
94 /* check if there is partial match */
95 if (strnicmp(data, pattern, data_limit - data) == 0)
101 if (strnicmp(data, pattern, plen) != 0) {
104 *start = data + plen;
106 for (data = *start; *data != term; data++) {
107 if (data == data_limit)
112 memset(p, 0, sizeof(p));
113 for (data = *start; data != *end; data++) {
114 if (*data >= '0' && *data <= '9') {
115 p[i] = p[i]*10 + *data - '0';
116 } else if (*data == ',' && i < 5) {
119 /* unexpected character */
127 *addr = (p[3]<<24) | (p[2]<<16) | (p[1]<<8) | p[0];
128 *port = (p[5]<<8) | p[4];
134 * Look at outgoing ftp packets to catch the response to a PASV command
135 * from the server (inside-to-outside).
136 * When we see one, we build a connection entry with the client address,
137 * client port 0 (unknown at the moment), the server address and the
138 * server port. Mark the current connection entry as a control channel
139 * of the new entry. All this work is just to make the data connection
140 * can be scheduled to the right server later.
142 * The outgoing packet should be something like
143 * "227 Entering Passive Mode (xxx,xxx,xxx,xxx,ppp,ppp)".
144 * xxx,xxx,xxx,xxx is the server address, ppp,ppp is the server port number.
146 static int ip_vs_ftp_out(struct ip_vs_app *app, struct ip_vs_conn *cp,
147 struct sk_buff **pskb, int *diff)
151 char *data, *data_limit;
155 struct ip_vs_conn *n_cp;
156 char buf[24]; /* xxx.xxx.xxx.xxx,ppp,ppp\000 */
162 /* Only useful for established sessions */
163 if (cp->state != IP_VS_TCP_S_ESTABLISHED)
166 /* Linear packets are much easier to deal with. */
167 if (!ip_vs_make_skb_writable(pskb, (*pskb)->len))
170 if (cp->app_data == &ip_vs_ftp_pasv) {
171 iph = (*pskb)->nh.iph;
172 th = (struct tcphdr *)&(((char *)iph)[iph->ihl*4]);
173 data = (char *)th + (th->doff << 2);
174 data_limit = (*pskb)->tail;
176 if (ip_vs_ftp_get_addrport(data, data_limit,
178 sizeof(SERVER_STRING)-1, ')',
183 IP_VS_DBG(1-debug, "PASV response (%u.%u.%u.%u:%d) -> "
184 "%u.%u.%u.%u:%d detected\n",
185 NIPQUAD(from), ntohs(port), NIPQUAD(cp->caddr), 0);
188 * Now update or create an connection entry for it
190 n_cp = ip_vs_conn_out_get(iph->protocol, from, port,
193 n_cp = ip_vs_conn_new(IPPROTO_TCP,
197 IP_VS_CONN_F_NO_CPORT,
202 /* add its controller */
203 ip_vs_control_add(n_cp, cp);
207 * Replace the old passive address with the new one
211 sprintf(buf,"%d,%d,%d,%d,%d,%d", NIPQUAD(from),
212 port&255, (port>>8)&255);
213 buf_len = strlen(buf);
216 * Calculate required delta-offset to keep TCP happy
218 *diff = buf_len - (end-start);
221 /* simply replace it with new passive address */
222 memcpy(start, buf, buf_len);
225 ret = !ip_vs_skb_replace(*pskb, GFP_ATOMIC, start,
226 end-start, buf, buf_len);
230 ip_vs_tcp_conn_listen(n_cp);
231 ip_vs_conn_put(n_cp);
239 * Look at incoming ftp packets to catch the PASV/PORT command
240 * (outside-to-inside).
242 * The incoming packet having the PORT command should be something like
243 * "PORT xxx,xxx,xxx,xxx,ppp,ppp\n".
244 * xxx,xxx,xxx,xxx is the client address, ppp,ppp is the client port number.
245 * In this case, we create a connection entry using the client address and
246 * port, so that the active ftp data connection from the server can reach
249 static int ip_vs_ftp_in(struct ip_vs_app *app, struct ip_vs_conn *cp,
250 struct sk_buff **pskb, int *diff)
254 char *data, *data_start, *data_limit;
258 struct ip_vs_conn *n_cp;
260 /* no diff required for incoming packets */
263 /* Only useful for established sessions */
264 if (cp->state != IP_VS_TCP_S_ESTABLISHED)
267 /* Linear packets are much easier to deal with. */
268 if (!ip_vs_make_skb_writable(pskb, (*pskb)->len))
272 * Detecting whether it is passive
274 iph = (*pskb)->nh.iph;
275 th = (struct tcphdr *)&(((char *)iph)[iph->ihl*4]);
277 /* Since there may be OPTIONS in the TCP packet and the HLEN is
278 the length of the header in 32-bit multiples, it is accurate
279 to calculate data address by th+HLEN*4 */
280 data = data_start = (char *)th + (th->doff << 2);
281 data_limit = (*pskb)->tail;
283 while (data <= data_limit - 6) {
284 if (strnicmp(data, "PASV\r\n", 6) == 0) {
285 /* Passive mode on */
286 IP_VS_DBG(1-debug, "got PASV at %d of %d\n",
288 data_limit - data_start);
289 cp->app_data = &ip_vs_ftp_pasv;
296 * To support virtual FTP server, the scenerio is as follows:
297 * FTP client ----> Load Balancer ----> FTP server
298 * First detect the port number in the application data,
299 * then create a new connection entry for the coming data
302 if (ip_vs_ftp_get_addrport(data_start, data_limit,
303 CLIENT_STRING, sizeof(CLIENT_STRING)-1,
308 IP_VS_DBG(1-debug, "PORT %u.%u.%u.%u:%d detected\n",
309 NIPQUAD(to), ntohs(port));
311 /* Passive mode off */
315 * Now update or create a connection entry for it
317 IP_VS_DBG(1-debug, "protocol %s %u.%u.%u.%u:%d %u.%u.%u.%u:%d\n",
318 ip_vs_proto_name(iph->protocol),
319 NIPQUAD(to), ntohs(port), NIPQUAD(cp->vaddr), 0);
321 n_cp = ip_vs_conn_in_get(iph->protocol,
323 cp->vaddr, htons(ntohs(cp->vport)-1));
325 n_cp = ip_vs_conn_new(IPPROTO_TCP,
327 cp->vaddr, htons(ntohs(cp->vport)-1),
328 cp->daddr, htons(ntohs(cp->dport)-1),
334 /* add its controller */
335 ip_vs_control_add(n_cp, cp);
339 * Move tunnel to listen state
341 ip_vs_tcp_conn_listen(n_cp);
342 ip_vs_conn_put(n_cp);
348 static struct ip_vs_app ip_vs_ftp = {
350 .type = IP_VS_APP_TYPE_FTP,
351 .protocol = IPPROTO_TCP,
352 .module = THIS_MODULE,
353 .incs_list = LIST_HEAD_INIT(ip_vs_ftp.incs_list),
354 .init_conn = ip_vs_ftp_init_conn,
355 .done_conn = ip_vs_ftp_done_conn,
358 .pkt_out = ip_vs_ftp_out,
359 .pkt_in = ip_vs_ftp_in,
364 * ip_vs_ftp initialization
366 static int __init ip_vs_ftp_init(void)
369 struct ip_vs_app *app = &ip_vs_ftp;
371 ret = register_ip_vs_app(app);
375 for (i=0; i<IP_VS_APP_MAX_PORTS; i++) {
378 ret = register_ip_vs_app_inc(app, app->protocol, ports[i]);
381 IP_VS_DBG(1-debug, "%s: loaded support on port[%d] = %d\n",
382 app->name, i, ports[i]);
386 unregister_ip_vs_app(app);
395 static void __exit ip_vs_ftp_exit(void)
397 unregister_ip_vs_app(&ip_vs_ftp);
401 module_init(ip_vs_ftp_init);
402 module_exit(ip_vs_ftp_exit);
403 MODULE_LICENSE("GPL");