[IPV4]: reset IPCB flags when neccessary
[linux-2.6] / net / ipv4 / ipvs / ip_vs_proto_udp.c
1 /*
2  * ip_vs_proto_udp.c:   UDP load balancing support for IPVS
3  *
4  * Version:     $Id: ip_vs_proto_udp.c,v 1.3 2002/11/30 01:50:35 wensong Exp $
5  *
6  * Authors:     Wensong Zhang <wensong@linuxvirtualserver.org>
7  *              Julian Anastasov <ja@ssi.bg>
8  *
9  *              This program is free software; you can redistribute it and/or
10  *              modify it under the terms of the GNU General Public License
11  *              as published by the Free Software Foundation; either version
12  *              2 of the License, or (at your option) any later version.
13  *
14  * Changes:
15  *
16  */
17
18 #include <linux/in.h>
19 #include <linux/ip.h>
20 #include <linux/kernel.h>
21 #include <linux/netfilter_ipv4.h>
22 #include <linux/udp.h>
23
24 #include <net/ip_vs.h>
25
26
27 static struct ip_vs_conn *
28 udp_conn_in_get(const struct sk_buff *skb, struct ip_vs_protocol *pp,
29                 const struct iphdr *iph, unsigned int proto_off, int inverse)
30 {
31         struct ip_vs_conn *cp;
32         __u16 _ports[2], *pptr;
33
34         pptr = skb_header_pointer(skb, proto_off, sizeof(_ports), _ports);
35         if (pptr == NULL)
36                 return NULL;
37
38         if (likely(!inverse)) {
39                 cp = ip_vs_conn_in_get(iph->protocol,
40                                        iph->saddr, pptr[0],
41                                        iph->daddr, pptr[1]);
42         } else {
43                 cp = ip_vs_conn_in_get(iph->protocol,
44                                        iph->daddr, pptr[1],
45                                        iph->saddr, pptr[0]);
46         }
47
48         return cp;
49 }
50
51
52 static struct ip_vs_conn *
53 udp_conn_out_get(const struct sk_buff *skb, struct ip_vs_protocol *pp,
54                  const struct iphdr *iph, unsigned int proto_off, int inverse)
55 {
56         struct ip_vs_conn *cp;
57         __u16 _ports[2], *pptr;
58
59         pptr = skb_header_pointer(skb, skb->nh.iph->ihl*4,
60                                   sizeof(_ports), _ports);
61         if (pptr == NULL)
62                 return NULL;
63
64         if (likely(!inverse)) {
65                 cp = ip_vs_conn_out_get(iph->protocol,
66                                         iph->saddr, pptr[0],
67                                         iph->daddr, pptr[1]);
68         } else {
69                 cp = ip_vs_conn_out_get(iph->protocol,
70                                         iph->daddr, pptr[1],
71                                         iph->saddr, pptr[0]);
72         }
73
74         return cp;
75 }
76
77
78 static int
79 udp_conn_schedule(struct sk_buff *skb, struct ip_vs_protocol *pp,
80                   int *verdict, struct ip_vs_conn **cpp)
81 {
82         struct ip_vs_service *svc;
83         struct udphdr _udph, *uh;
84
85         uh = skb_header_pointer(skb, skb->nh.iph->ihl*4,
86                                 sizeof(_udph), &_udph);
87         if (uh == NULL) {
88                 *verdict = NF_DROP;
89                 return 0;
90         }
91
92         if ((svc = ip_vs_service_get(skb->nfmark, skb->nh.iph->protocol,
93                                      skb->nh.iph->daddr, uh->dest))) {
94                 if (ip_vs_todrop()) {
95                         /*
96                          * It seems that we are very loaded.
97                          * We have to drop this packet :(
98                          */
99                         ip_vs_service_put(svc);
100                         *verdict = NF_DROP;
101                         return 0;
102                 }
103
104                 /*
105                  * Let the virtual server select a real server for the
106                  * incoming connection, and create a connection entry.
107                  */
108                 *cpp = ip_vs_schedule(svc, skb);
109                 if (!*cpp) {
110                         *verdict = ip_vs_leave(svc, skb, pp);
111                         return 0;
112                 }
113                 ip_vs_service_put(svc);
114         }
115         return 1;
116 }
117
118
119 static inline void
120 udp_fast_csum_update(struct udphdr *uhdr, u32 oldip, u32 newip,
121                      u16 oldport, u16 newport)
122 {
123         uhdr->check =
124                 ip_vs_check_diff(~oldip, newip,
125                                  ip_vs_check_diff(oldport ^ 0xFFFF,
126                                                   newport, uhdr->check));
127         if (!uhdr->check)
128                 uhdr->check = 0xFFFF;
129 }
130
131 static int
132 udp_snat_handler(struct sk_buff **pskb,
133                  struct ip_vs_protocol *pp, struct ip_vs_conn *cp)
134 {
135         struct udphdr *udph;
136         unsigned int udphoff = (*pskb)->nh.iph->ihl * 4;
137
138         /* csum_check requires unshared skb */
139         if (!ip_vs_make_skb_writable(pskb, udphoff+sizeof(*udph)))
140                 return 0;
141
142         if (unlikely(cp->app != NULL)) {
143                 /* Some checks before mangling */
144                 if (pp->csum_check && !pp->csum_check(*pskb, pp))
145                         return 0;
146
147                 /*
148                  *      Call application helper if needed
149                  */
150                 if (!ip_vs_app_pkt_out(cp, pskb))
151                         return 0;
152         }
153
154         udph = (void *)(*pskb)->nh.iph + udphoff;
155         udph->source = cp->vport;
156
157         /*
158          *      Adjust UDP checksums
159          */
160         if (!cp->app && (udph->check != 0)) {
161                 /* Only port and addr are changed, do fast csum update */
162                 udp_fast_csum_update(udph, cp->daddr, cp->vaddr,
163                                      cp->dport, cp->vport);
164                 if ((*pskb)->ip_summed == CHECKSUM_HW)
165                         (*pskb)->ip_summed = CHECKSUM_NONE;
166         } else {
167                 /* full checksum calculation */
168                 udph->check = 0;
169                 (*pskb)->csum = skb_checksum(*pskb, udphoff,
170                                              (*pskb)->len - udphoff, 0);
171                 udph->check = csum_tcpudp_magic(cp->vaddr, cp->caddr,
172                                                 (*pskb)->len - udphoff,
173                                                 cp->protocol,
174                                                 (*pskb)->csum);
175                 if (udph->check == 0)
176                         udph->check = 0xFFFF;
177                 IP_VS_DBG(11, "O-pkt: %s O-csum=%d (+%zd)\n",
178                           pp->name, udph->check,
179                           (char*)&(udph->check) - (char*)udph);
180         }
181         return 1;
182 }
183
184
185 static int
186 udp_dnat_handler(struct sk_buff **pskb,
187                  struct ip_vs_protocol *pp, struct ip_vs_conn *cp)
188 {
189         struct udphdr *udph;
190         unsigned int udphoff = (*pskb)->nh.iph->ihl * 4;
191
192         /* csum_check requires unshared skb */
193         if (!ip_vs_make_skb_writable(pskb, udphoff+sizeof(*udph)))
194                 return 0;
195
196         if (unlikely(cp->app != NULL)) {
197                 /* Some checks before mangling */
198                 if (pp->csum_check && !pp->csum_check(*pskb, pp))
199                         return 0;
200
201                 /*
202                  *      Attempt ip_vs_app call.
203                  *      It will fix ip_vs_conn
204                  */
205                 if (!ip_vs_app_pkt_in(cp, pskb))
206                         return 0;
207         }
208
209         udph = (void *)(*pskb)->nh.iph + udphoff;
210         udph->dest = cp->dport;
211
212         /*
213          *      Adjust UDP checksums
214          */
215         if (!cp->app && (udph->check != 0)) {
216                 /* Only port and addr are changed, do fast csum update */
217                 udp_fast_csum_update(udph, cp->vaddr, cp->daddr,
218                                      cp->vport, cp->dport);
219                 if ((*pskb)->ip_summed == CHECKSUM_HW)
220                         (*pskb)->ip_summed = CHECKSUM_NONE;
221         } else {
222                 /* full checksum calculation */
223                 udph->check = 0;
224                 (*pskb)->csum = skb_checksum(*pskb, udphoff,
225                                              (*pskb)->len - udphoff, 0);
226                 udph->check = csum_tcpudp_magic(cp->caddr, cp->daddr,
227                                                 (*pskb)->len - udphoff,
228                                                 cp->protocol,
229                                                 (*pskb)->csum);
230                 if (udph->check == 0)
231                         udph->check = 0xFFFF;
232                 (*pskb)->ip_summed = CHECKSUM_UNNECESSARY;
233         }
234         return 1;
235 }
236
237
238 static int
239 udp_csum_check(struct sk_buff *skb, struct ip_vs_protocol *pp)
240 {
241         struct udphdr _udph, *uh;
242         unsigned int udphoff = skb->nh.iph->ihl*4;
243
244         uh = skb_header_pointer(skb, udphoff, sizeof(_udph), &_udph);
245         if (uh == NULL)
246                 return 0;
247
248         if (uh->check != 0) {
249                 switch (skb->ip_summed) {
250                 case CHECKSUM_NONE:
251                         skb->csum = skb_checksum(skb, udphoff,
252                                                  skb->len - udphoff, 0);
253                 case CHECKSUM_HW:
254                         if (csum_tcpudp_magic(skb->nh.iph->saddr,
255                                               skb->nh.iph->daddr,
256                                               skb->len - udphoff,
257                                               skb->nh.iph->protocol,
258                                               skb->csum)) {
259                                 IP_VS_DBG_RL_PKT(0, pp, skb, 0,
260                                                  "Failed checksum for");
261                                 return 0;
262                         }
263                         break;
264                 default:
265                         /* CHECKSUM_UNNECESSARY */
266                         break;
267                 }
268         }
269         return 1;
270 }
271
272
273 /*
274  *      Note: the caller guarantees that only one of register_app,
275  *      unregister_app or app_conn_bind is called each time.
276  */
277
278 #define UDP_APP_TAB_BITS        4
279 #define UDP_APP_TAB_SIZE        (1 << UDP_APP_TAB_BITS)
280 #define UDP_APP_TAB_MASK        (UDP_APP_TAB_SIZE - 1)
281
282 static struct list_head udp_apps[UDP_APP_TAB_SIZE];
283 static DEFINE_SPINLOCK(udp_app_lock);
284
285 static inline __u16 udp_app_hashkey(__u16 port)
286 {
287         return ((port >> UDP_APP_TAB_BITS) ^ port) & UDP_APP_TAB_MASK;
288 }
289
290
291 static int udp_register_app(struct ip_vs_app *inc)
292 {
293         struct ip_vs_app *i;
294         __u16 hash, port = inc->port;
295         int ret = 0;
296
297         hash = udp_app_hashkey(port);
298
299
300         spin_lock_bh(&udp_app_lock);
301         list_for_each_entry(i, &udp_apps[hash], p_list) {
302                 if (i->port == port) {
303                         ret = -EEXIST;
304                         goto out;
305                 }
306         }
307         list_add(&inc->p_list, &udp_apps[hash]);
308         atomic_inc(&ip_vs_protocol_udp.appcnt);
309
310   out:
311         spin_unlock_bh(&udp_app_lock);
312         return ret;
313 }
314
315
316 static void
317 udp_unregister_app(struct ip_vs_app *inc)
318 {
319         spin_lock_bh(&udp_app_lock);
320         atomic_dec(&ip_vs_protocol_udp.appcnt);
321         list_del(&inc->p_list);
322         spin_unlock_bh(&udp_app_lock);
323 }
324
325
326 static int udp_app_conn_bind(struct ip_vs_conn *cp)
327 {
328         int hash;
329         struct ip_vs_app *inc;
330         int result = 0;
331
332         /* Default binding: bind app only for NAT */
333         if (IP_VS_FWD_METHOD(cp) != IP_VS_CONN_F_MASQ)
334                 return 0;
335
336         /* Lookup application incarnations and bind the right one */
337         hash = udp_app_hashkey(cp->vport);
338
339         spin_lock(&udp_app_lock);
340         list_for_each_entry(inc, &udp_apps[hash], p_list) {
341                 if (inc->port == cp->vport) {
342                         if (unlikely(!ip_vs_app_inc_get(inc)))
343                                 break;
344                         spin_unlock(&udp_app_lock);
345
346                         IP_VS_DBG(9, "%s: Binding conn %u.%u.%u.%u:%u->"
347                                   "%u.%u.%u.%u:%u to app %s on port %u\n",
348                                   __FUNCTION__,
349                                   NIPQUAD(cp->caddr), ntohs(cp->cport),
350                                   NIPQUAD(cp->vaddr), ntohs(cp->vport),
351                                   inc->name, ntohs(inc->port));
352                         cp->app = inc;
353                         if (inc->init_conn)
354                                 result = inc->init_conn(inc, cp);
355                         goto out;
356                 }
357         }
358         spin_unlock(&udp_app_lock);
359
360   out:
361         return result;
362 }
363
364
365 static int udp_timeouts[IP_VS_UDP_S_LAST+1] = {
366         [IP_VS_UDP_S_NORMAL]            =       5*60*HZ,
367         [IP_VS_UDP_S_LAST]              =       2*HZ,
368 };
369
370 static char * udp_state_name_table[IP_VS_UDP_S_LAST+1] = {
371         [IP_VS_UDP_S_NORMAL]            =       "UDP",
372         [IP_VS_UDP_S_LAST]              =       "BUG!",
373 };
374
375
376 static int
377 udp_set_state_timeout(struct ip_vs_protocol *pp, char *sname, int to)
378 {
379         return ip_vs_set_state_timeout(pp->timeout_table, IP_VS_UDP_S_LAST,
380                                        udp_state_name_table, sname, to);
381 }
382
383 static const char * udp_state_name(int state)
384 {
385         if (state >= IP_VS_UDP_S_LAST)
386                 return "ERR!";
387         return udp_state_name_table[state] ? udp_state_name_table[state] : "?";
388 }
389
390 static int
391 udp_state_transition(struct ip_vs_conn *cp, int direction,
392                      const struct sk_buff *skb,
393                      struct ip_vs_protocol *pp)
394 {
395         cp->timeout = pp->timeout_table[IP_VS_UDP_S_NORMAL];
396         return 1;
397 }
398
399 static void udp_init(struct ip_vs_protocol *pp)
400 {
401         IP_VS_INIT_HASH_TABLE(udp_apps);
402         pp->timeout_table = udp_timeouts;
403 }
404
405 static void udp_exit(struct ip_vs_protocol *pp)
406 {
407 }
408
409
410 struct ip_vs_protocol ip_vs_protocol_udp = {
411         .name =                 "UDP",
412         .protocol =             IPPROTO_UDP,
413         .dont_defrag =          0,
414         .init =                 udp_init,
415         .exit =                 udp_exit,
416         .conn_schedule =        udp_conn_schedule,
417         .conn_in_get =          udp_conn_in_get,
418         .conn_out_get =         udp_conn_out_get,
419         .snat_handler =         udp_snat_handler,
420         .dnat_handler =         udp_dnat_handler,
421         .csum_check =           udp_csum_check,
422         .state_transition =     udp_state_transition,
423         .state_name =           udp_state_name,
424         .register_app =         udp_register_app,
425         .unregister_app =       udp_unregister_app,
426         .app_conn_bind =        udp_app_conn_bind,
427         .debug_packet =         ip_vs_tcpudp_debug_packet,
428         .timeout_change =       NULL,
429         .set_state_timeout =    udp_set_state_timeout,
430 };