[NET]: "signed long" -> "long"
[linux-2.6.git] / net / dccp / ipv4.c
1 /*
2  *  net/dccp/ipv4.c
3  *
4  *  An implementation of the DCCP protocol
5  *  Arnaldo Carvalho de Melo <acme@conectiva.com.br>
6  *
7  *      This program is free software; you can redistribute it and/or
8  *      modify it under the terms of the GNU General Public License
9  *      as published by the Free Software Foundation; either version
10  *      2 of the License, or (at your option) any later version.
11  */
12
13 #include <linux/config.h>
14 #include <linux/dccp.h>
15 #include <linux/icmp.h>
16 #include <linux/module.h>
17 #include <linux/skbuff.h>
18 #include <linux/random.h>
19
20 #include <net/icmp.h>
21 #include <net/inet_hashtables.h>
22 #include <net/inet_sock.h>
23 #include <net/sock.h>
24 #include <net/timewait_sock.h>
25 #include <net/tcp_states.h>
26 #include <net/xfrm.h>
27
28 #include "ackvec.h"
29 #include "ccid.h"
30 #include "dccp.h"
31
32 struct inet_hashinfo __cacheline_aligned dccp_hashinfo = {
33         .lhash_lock     = RW_LOCK_UNLOCKED,
34         .lhash_users    = ATOMIC_INIT(0),
35         .lhash_wait = __WAIT_QUEUE_HEAD_INITIALIZER(dccp_hashinfo.lhash_wait),
36 };
37
38 EXPORT_SYMBOL_GPL(dccp_hashinfo);
39
40 static int dccp_v4_get_port(struct sock *sk, const unsigned short snum)
41 {
42         return inet_csk_get_port(&dccp_hashinfo, sk, snum,
43                                  inet_csk_bind_conflict);
44 }
45
46 static void dccp_v4_hash(struct sock *sk)
47 {
48         inet_hash(&dccp_hashinfo, sk);
49 }
50
51 void dccp_unhash(struct sock *sk)
52 {
53         inet_unhash(&dccp_hashinfo, sk);
54 }
55
56 EXPORT_SYMBOL_GPL(dccp_unhash);
57
58 int dccp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
59 {
60         struct inet_sock *inet = inet_sk(sk);
61         struct dccp_sock *dp = dccp_sk(sk);
62         const struct sockaddr_in *usin = (struct sockaddr_in *)uaddr;
63         struct rtable *rt;
64         u32 daddr, nexthop;
65         int tmp;
66         int err;
67
68         dp->dccps_role = DCCP_ROLE_CLIENT;
69
70         if (dccp_service_not_initialized(sk))
71                 return -EPROTO;
72
73         if (addr_len < sizeof(struct sockaddr_in))
74                 return -EINVAL;
75
76         if (usin->sin_family != AF_INET)
77                 return -EAFNOSUPPORT;
78
79         nexthop = daddr = usin->sin_addr.s_addr;
80         if (inet->opt != NULL && inet->opt->srr) {
81                 if (daddr == 0)
82                         return -EINVAL;
83                 nexthop = inet->opt->faddr;
84         }
85
86         tmp = ip_route_connect(&rt, nexthop, inet->saddr,
87                                RT_CONN_FLAGS(sk), sk->sk_bound_dev_if,
88                                IPPROTO_DCCP,
89                                inet->sport, usin->sin_port, sk);
90         if (tmp < 0)
91                 return tmp;
92
93         if (rt->rt_flags & (RTCF_MULTICAST | RTCF_BROADCAST)) {
94                 ip_rt_put(rt);
95                 return -ENETUNREACH;
96         }
97
98         if (inet->opt == NULL || !inet->opt->srr)
99                 daddr = rt->rt_dst;
100
101         if (inet->saddr == 0)
102                 inet->saddr = rt->rt_src;
103         inet->rcv_saddr = inet->saddr;
104
105         inet->dport = usin->sin_port;
106         inet->daddr = daddr;
107
108         inet_csk(sk)->icsk_ext_hdr_len = 0;
109         if (inet->opt != NULL)
110                 inet_csk(sk)->icsk_ext_hdr_len = inet->opt->optlen;
111         /*
112          * Socket identity is still unknown (sport may be zero).
113          * However we set state to DCCP_REQUESTING and not releasing socket
114          * lock select source port, enter ourselves into the hash tables and
115          * complete initialization after this.
116          */
117         dccp_set_state(sk, DCCP_REQUESTING);
118         err = inet_hash_connect(&dccp_death_row, sk);
119         if (err != 0)
120                 goto failure;
121
122         err = ip_route_newports(&rt, inet->sport, inet->dport, sk);
123         if (err != 0)
124                 goto failure;
125
126         /* OK, now commit destination to socket.  */
127         sk_setup_caps(sk, &rt->u.dst);
128
129         dp->dccps_gar =
130                 dp->dccps_iss = secure_dccp_sequence_number(inet->saddr,
131                                                             inet->daddr,
132                                                             inet->sport,
133                                                             usin->sin_port);
134         dccp_update_gss(sk, dp->dccps_iss);
135
136         inet->id = dp->dccps_iss ^ jiffies;
137
138         err = dccp_connect(sk);
139         rt = NULL;
140         if (err != 0)
141                 goto failure;
142 out:
143         return err;
144 failure:
145         /*
146          * This unhashes the socket and releases the local port, if necessary.
147          */
148         dccp_set_state(sk, DCCP_CLOSED);
149         ip_rt_put(rt);
150         sk->sk_route_caps = 0;
151         inet->dport = 0;
152         goto out;
153 }
154
155 EXPORT_SYMBOL_GPL(dccp_v4_connect);
156
157 /*
158  * This routine does path mtu discovery as defined in RFC1191.
159  */
160 static inline void dccp_do_pmtu_discovery(struct sock *sk,
161                                           const struct iphdr *iph,
162                                           u32 mtu)
163 {
164         struct dst_entry *dst;
165         const struct inet_sock *inet = inet_sk(sk);
166         const struct dccp_sock *dp = dccp_sk(sk);
167
168         /* We are not interested in DCCP_LISTEN and request_socks (RESPONSEs
169          * send out by Linux are always < 576bytes so they should go through
170          * unfragmented).
171          */
172         if (sk->sk_state == DCCP_LISTEN)
173                 return;
174
175         /* We don't check in the destentry if pmtu discovery is forbidden
176          * on this route. We just assume that no packet_to_big packets
177          * are send back when pmtu discovery is not active.
178          * There is a small race when the user changes this flag in the
179          * route, but I think that's acceptable.
180          */
181         if ((dst = __sk_dst_check(sk, 0)) == NULL)
182                 return;
183
184         dst->ops->update_pmtu(dst, mtu);
185
186         /* Something is about to be wrong... Remember soft error
187          * for the case, if this connection will not able to recover.
188          */
189         if (mtu < dst_mtu(dst) && ip_dont_fragment(sk, dst))
190                 sk->sk_err_soft = EMSGSIZE;
191
192         mtu = dst_mtu(dst);
193
194         if (inet->pmtudisc != IP_PMTUDISC_DONT &&
195             inet_csk(sk)->icsk_pmtu_cookie > mtu) {
196                 dccp_sync_mss(sk, mtu);
197
198                 /*
199                  * From: draft-ietf-dccp-spec-11.txt
200                  *
201                  *      DCCP-Sync packets are the best choice for upward
202                  *      probing, since DCCP-Sync probes do not risk application
203                  *      data loss.
204                  */
205                 dccp_send_sync(sk, dp->dccps_gsr, DCCP_PKT_SYNC);
206         } /* else let the usual retransmit timer handle it */
207 }
208
209 static void dccp_v4_ctl_send_ack(struct sk_buff *rxskb)
210 {
211         int err;
212         struct dccp_hdr *rxdh = dccp_hdr(rxskb), *dh;
213         const int dccp_hdr_ack_len = sizeof(struct dccp_hdr) +
214                                      sizeof(struct dccp_hdr_ext) +
215                                      sizeof(struct dccp_hdr_ack_bits);
216         struct sk_buff *skb;
217
218         if (((struct rtable *)rxskb->dst)->rt_type != RTN_LOCAL)
219                 return;
220
221         skb = alloc_skb(MAX_DCCP_HEADER + 15, GFP_ATOMIC);
222         if (skb == NULL)
223                 return;
224
225         /* Reserve space for headers. */
226         skb_reserve(skb, MAX_DCCP_HEADER);
227
228         skb->dst = dst_clone(rxskb->dst);
229
230         skb->h.raw = skb_push(skb, dccp_hdr_ack_len);
231         dh = dccp_hdr(skb);
232         memset(dh, 0, dccp_hdr_ack_len);
233
234         /* Build DCCP header and checksum it. */
235         dh->dccph_type     = DCCP_PKT_ACK;
236         dh->dccph_sport    = rxdh->dccph_dport;
237         dh->dccph_dport    = rxdh->dccph_sport;
238         dh->dccph_doff     = dccp_hdr_ack_len / 4;
239         dh->dccph_x        = 1;
240
241         dccp_hdr_set_seq(dh, DCCP_SKB_CB(rxskb)->dccpd_ack_seq);
242         dccp_hdr_set_ack(dccp_hdr_ack_bits(skb),
243                          DCCP_SKB_CB(rxskb)->dccpd_seq);
244
245         bh_lock_sock(dccp_ctl_socket->sk);
246         err = ip_build_and_send_pkt(skb, dccp_ctl_socket->sk,
247                                     rxskb->nh.iph->daddr,
248                                     rxskb->nh.iph->saddr, NULL);
249         bh_unlock_sock(dccp_ctl_socket->sk);
250
251         if (err == NET_XMIT_CN || err == 0) {
252                 DCCP_INC_STATS_BH(DCCP_MIB_OUTSEGS);
253                 DCCP_INC_STATS_BH(DCCP_MIB_OUTRSTS);
254         }
255 }
256
257 static void dccp_v4_reqsk_send_ack(struct sk_buff *skb,
258                                    struct request_sock *req)
259 {
260         dccp_v4_ctl_send_ack(skb);
261 }
262
263 static int dccp_v4_send_response(struct sock *sk, struct request_sock *req,
264                                  struct dst_entry *dst)
265 {
266         int err = -1;
267         struct sk_buff *skb;
268
269         /* First, grab a route. */
270         
271         if (dst == NULL && (dst = inet_csk_route_req(sk, req)) == NULL)
272                 goto out;
273
274         skb = dccp_make_response(sk, dst, req);
275         if (skb != NULL) {
276                 const struct inet_request_sock *ireq = inet_rsk(req);
277
278                 memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
279                 err = ip_build_and_send_pkt(skb, sk, ireq->loc_addr,
280                                             ireq->rmt_addr,
281                                             ireq->opt);
282                 if (err == NET_XMIT_CN)
283                         err = 0;
284         }
285
286 out:
287         dst_release(dst);
288         return err;
289 }
290
291 /*
292  * This routine is called by the ICMP module when it gets some sort of error
293  * condition. If err < 0 then the socket should be closed and the error
294  * returned to the user. If err > 0 it's just the icmp type << 8 | icmp code.
295  * After adjustment header points to the first 8 bytes of the tcp header. We
296  * need to find the appropriate port.
297  *
298  * The locking strategy used here is very "optimistic". When someone else
299  * accesses the socket the ICMP is just dropped and for some paths there is no
300  * check at all. A more general error queue to queue errors for later handling
301  * is probably better.
302  */
303 void dccp_v4_err(struct sk_buff *skb, u32 info)
304 {
305         const struct iphdr *iph = (struct iphdr *)skb->data;
306         const struct dccp_hdr *dh = (struct dccp_hdr *)(skb->data +
307                                                         (iph->ihl << 2));
308         struct dccp_sock *dp;
309         struct inet_sock *inet;
310         const int type = skb->h.icmph->type;
311         const int code = skb->h.icmph->code;
312         struct sock *sk;
313         __u64 seq;
314         int err;
315
316         if (skb->len < (iph->ihl << 2) + 8) {
317                 ICMP_INC_STATS_BH(ICMP_MIB_INERRORS);
318                 return;
319         }
320
321         sk = inet_lookup(&dccp_hashinfo, iph->daddr, dh->dccph_dport,
322                          iph->saddr, dh->dccph_sport, inet_iif(skb));
323         if (sk == NULL) {
324                 ICMP_INC_STATS_BH(ICMP_MIB_INERRORS);
325                 return;
326         }
327
328         if (sk->sk_state == DCCP_TIME_WAIT) {
329                 inet_twsk_put((struct inet_timewait_sock *)sk);
330                 return;
331         }
332
333         bh_lock_sock(sk);
334         /* If too many ICMPs get dropped on busy
335          * servers this needs to be solved differently.
336          */
337         if (sock_owned_by_user(sk))
338                 NET_INC_STATS_BH(LINUX_MIB_LOCKDROPPEDICMPS);
339
340         if (sk->sk_state == DCCP_CLOSED)
341                 goto out;
342
343         dp = dccp_sk(sk);
344         seq = dccp_hdr_seq(skb);
345         if (sk->sk_state != DCCP_LISTEN &&
346             !between48(seq, dp->dccps_swl, dp->dccps_swh)) {
347                 NET_INC_STATS(LINUX_MIB_OUTOFWINDOWICMPS);
348                 goto out;
349         }
350
351         switch (type) {
352         case ICMP_SOURCE_QUENCH:
353                 /* Just silently ignore these. */
354                 goto out;
355         case ICMP_PARAMETERPROB:
356                 err = EPROTO;
357                 break;
358         case ICMP_DEST_UNREACH:
359                 if (code > NR_ICMP_UNREACH)
360                         goto out;
361
362                 if (code == ICMP_FRAG_NEEDED) { /* PMTU discovery (RFC1191) */
363                         if (!sock_owned_by_user(sk))
364                                 dccp_do_pmtu_discovery(sk, iph, info);
365                         goto out;
366                 }
367
368                 err = icmp_err_convert[code].errno;
369                 break;
370         case ICMP_TIME_EXCEEDED:
371                 err = EHOSTUNREACH;
372                 break;
373         default:
374                 goto out;
375         }
376
377         switch (sk->sk_state) {
378                 struct request_sock *req , **prev;
379         case DCCP_LISTEN:
380                 if (sock_owned_by_user(sk))
381                         goto out;
382                 req = inet_csk_search_req(sk, &prev, dh->dccph_dport,
383                                           iph->daddr, iph->saddr);
384                 if (!req)
385                         goto out;
386
387                 /*
388                  * ICMPs are not backlogged, hence we cannot get an established
389                  * socket here.
390                  */
391                 BUG_TRAP(!req->sk);
392
393                 if (seq != dccp_rsk(req)->dreq_iss) {
394                         NET_INC_STATS_BH(LINUX_MIB_OUTOFWINDOWICMPS);
395                         goto out;
396                 }
397                 /*
398                  * Still in RESPOND, just remove it silently.
399                  * There is no good way to pass the error to the newly
400                  * created socket, and POSIX does not want network
401                  * errors returned from accept().
402                  */
403                 inet_csk_reqsk_queue_drop(sk, req, prev);
404                 goto out;
405
406         case DCCP_REQUESTING:
407         case DCCP_RESPOND:
408                 if (!sock_owned_by_user(sk)) {
409                         DCCP_INC_STATS_BH(DCCP_MIB_ATTEMPTFAILS);
410                         sk->sk_err = err;
411
412                         sk->sk_error_report(sk);
413
414                         dccp_done(sk);
415                 } else
416                         sk->sk_err_soft = err;
417                 goto out;
418         }
419
420         /* If we've already connected we will keep trying
421          * until we time out, or the user gives up.
422          *
423          * rfc1122 4.2.3.9 allows to consider as hard errors
424          * only PROTO_UNREACH and PORT_UNREACH (well, FRAG_FAILED too,
425          * but it is obsoleted by pmtu discovery).
426          *
427          * Note, that in modern internet, where routing is unreliable
428          * and in each dark corner broken firewalls sit, sending random
429          * errors ordered by their masters even this two messages finally lose
430          * their original sense (even Linux sends invalid PORT_UNREACHs)
431          *
432          * Now we are in compliance with RFCs.
433          *                                                      --ANK (980905)
434          */
435
436         inet = inet_sk(sk);
437         if (!sock_owned_by_user(sk) && inet->recverr) {
438                 sk->sk_err = err;
439                 sk->sk_error_report(sk);
440         } else /* Only an error on timeout */
441                 sk->sk_err_soft = err;
442 out:
443         bh_unlock_sock(sk);
444         sock_put(sk);
445 }
446
447 /* This routine computes an IPv4 DCCP checksum. */
448 void dccp_v4_send_check(struct sock *sk, int len, struct sk_buff *skb)
449 {
450         const struct inet_sock *inet = inet_sk(sk);
451         struct dccp_hdr *dh = dccp_hdr(skb);
452
453         dh->dccph_checksum = dccp_v4_checksum(skb, inet->saddr, inet->daddr);
454 }
455
456 EXPORT_SYMBOL_GPL(dccp_v4_send_check);
457
458 int dccp_v4_send_reset(struct sock *sk, enum dccp_reset_codes code)
459 {
460         struct sk_buff *skb;
461         /*
462          * FIXME: what if rebuild_header fails?
463          * Should we be doing a rebuild_header here?
464          */
465         int err = inet_sk_rebuild_header(sk);
466
467         if (err != 0)
468                 return err;
469
470         skb = dccp_make_reset(sk, sk->sk_dst_cache, code);
471         if (skb != NULL) {
472                 const struct inet_sock *inet = inet_sk(sk);
473
474                 memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
475                 err = ip_build_and_send_pkt(skb, sk,
476                                             inet->saddr, inet->daddr, NULL);
477                 if (err == NET_XMIT_CN)
478                         err = 0;
479         }
480
481         return err;
482 }
483
484 static inline u64 dccp_v4_init_sequence(const struct sock *sk,
485                                         const struct sk_buff *skb)
486 {
487         return secure_dccp_sequence_number(skb->nh.iph->daddr,
488                                            skb->nh.iph->saddr,
489                                            dccp_hdr(skb)->dccph_dport,
490                                            dccp_hdr(skb)->dccph_sport);
491 }
492
493 int dccp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
494 {
495         struct inet_request_sock *ireq;
496         struct dccp_sock dp;
497         struct request_sock *req;
498         struct dccp_request_sock *dreq;
499         const __u32 saddr = skb->nh.iph->saddr;
500         const __u32 daddr = skb->nh.iph->daddr;
501         const __u32 service = dccp_hdr_request(skb)->dccph_req_service;
502         struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
503         __u8 reset_code = DCCP_RESET_CODE_TOO_BUSY;
504
505         /* Never answer to DCCP_PKT_REQUESTs send to broadcast or multicast */
506         if (((struct rtable *)skb->dst)->rt_flags &
507             (RTCF_BROADCAST | RTCF_MULTICAST)) {
508                 reset_code = DCCP_RESET_CODE_NO_CONNECTION;
509                 goto drop;
510         }
511
512         if (dccp_bad_service_code(sk, service)) {
513                 reset_code = DCCP_RESET_CODE_BAD_SERVICE_CODE;
514                 goto drop;
515         }
516         /*
517          * TW buckets are converted to open requests without
518          * limitations, they conserve resources and peer is
519          * evidently real one.
520          */
521         if (inet_csk_reqsk_queue_is_full(sk))
522                 goto drop;
523
524         /*
525          * Accept backlog is full. If we have already queued enough
526          * of warm entries in syn queue, drop request. It is better than
527          * clogging syn queue with openreqs with exponentially increasing
528          * timeout.
529          */
530         if (sk_acceptq_is_full(sk) && inet_csk_reqsk_queue_young(sk) > 1)
531                 goto drop;
532
533         req = reqsk_alloc(sk->sk_prot->rsk_prot);
534         if (req == NULL)
535                 goto drop;
536
537         /* FIXME: process options */
538
539         dccp_openreq_init(req, &dp, skb);
540
541         ireq = inet_rsk(req);
542         ireq->loc_addr = daddr;
543         ireq->rmt_addr = saddr;
544         req->rcv_wnd    = 100; /* Fake, option parsing will get the
545                                   right value */
546         ireq->opt       = NULL;
547
548         /* 
549          * Step 3: Process LISTEN state
550          *
551          * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookie
552          *
553          * In fact we defer setting S.GSR, S.SWL, S.SWH to
554          * dccp_create_openreq_child.
555          */
556         dreq = dccp_rsk(req);
557         dreq->dreq_isr     = dcb->dccpd_seq;
558         dreq->dreq_iss     = dccp_v4_init_sequence(sk, skb);
559         dreq->dreq_service = service;
560
561         if (dccp_v4_send_response(sk, req, NULL))
562                 goto drop_and_free;
563
564         inet_csk_reqsk_queue_hash_add(sk, req, DCCP_TIMEOUT_INIT);
565         return 0;
566
567 drop_and_free:
568         reqsk_free(req);
569 drop:
570         DCCP_INC_STATS_BH(DCCP_MIB_ATTEMPTFAILS);
571         dcb->dccpd_reset_code = reset_code;
572         return -1;
573 }
574
575 EXPORT_SYMBOL_GPL(dccp_v4_conn_request);
576
577 /*
578  * The three way handshake has completed - we got a valid ACK or DATAACK -
579  * now create the new socket.
580  *
581  * This is the equivalent of TCP's tcp_v4_syn_recv_sock
582  */
583 struct sock *dccp_v4_request_recv_sock(struct sock *sk, struct sk_buff *skb,
584                                        struct request_sock *req,
585                                        struct dst_entry *dst)
586 {
587         struct inet_request_sock *ireq;
588         struct inet_sock *newinet;
589         struct dccp_sock *newdp;
590         struct sock *newsk;
591
592         if (sk_acceptq_is_full(sk))
593                 goto exit_overflow;
594
595         if (dst == NULL && (dst = inet_csk_route_req(sk, req)) == NULL)
596                 goto exit;
597
598         newsk = dccp_create_openreq_child(sk, req, skb);
599         if (newsk == NULL)
600                 goto exit;
601
602         sk_setup_caps(newsk, dst);
603
604         newdp              = dccp_sk(newsk);
605         newinet            = inet_sk(newsk);
606         ireq               = inet_rsk(req);
607         newinet->daddr     = ireq->rmt_addr;
608         newinet->rcv_saddr = ireq->loc_addr;
609         newinet->saddr     = ireq->loc_addr;
610         newinet->opt       = ireq->opt;
611         ireq->opt          = NULL;
612         newinet->mc_index  = inet_iif(skb);
613         newinet->mc_ttl    = skb->nh.iph->ttl;
614         newinet->id        = jiffies;
615
616         dccp_sync_mss(newsk, dst_mtu(dst));
617
618         __inet_hash(&dccp_hashinfo, newsk, 0);
619         __inet_inherit_port(&dccp_hashinfo, sk, newsk);
620
621         return newsk;
622
623 exit_overflow:
624         NET_INC_STATS_BH(LINUX_MIB_LISTENOVERFLOWS);
625 exit:
626         NET_INC_STATS_BH(LINUX_MIB_LISTENDROPS);
627         dst_release(dst);
628         return NULL;
629 }
630
631 EXPORT_SYMBOL_GPL(dccp_v4_request_recv_sock);
632
633 static struct sock *dccp_v4_hnd_req(struct sock *sk, struct sk_buff *skb)
634 {
635         const struct dccp_hdr *dh = dccp_hdr(skb);
636         const struct iphdr *iph = skb->nh.iph;
637         struct sock *nsk;
638         struct request_sock **prev;
639         /* Find possible connection requests. */
640         struct request_sock *req = inet_csk_search_req(sk, &prev,
641                                                        dh->dccph_sport,
642                                                        iph->saddr, iph->daddr);
643         if (req != NULL)
644                 return dccp_check_req(sk, skb, req, prev);
645
646         nsk = __inet_lookup_established(&dccp_hashinfo,
647                                         iph->saddr, dh->dccph_sport,
648                                         iph->daddr, ntohs(dh->dccph_dport),
649                                         inet_iif(skb));
650         if (nsk != NULL) {
651                 if (nsk->sk_state != DCCP_TIME_WAIT) {
652                         bh_lock_sock(nsk);
653                         return nsk;
654                 }
655                 inet_twsk_put((struct inet_timewait_sock *)nsk);
656                 return NULL;
657         }
658
659         return sk;
660 }
661
662 int dccp_v4_checksum(const struct sk_buff *skb, const u32 saddr,
663                      const u32 daddr)
664 {
665         const struct dccp_hdr* dh = dccp_hdr(skb);
666         int checksum_len;
667         u32 tmp;
668
669         if (dh->dccph_cscov == 0)
670                 checksum_len = skb->len;
671         else {
672                 checksum_len = (dh->dccph_cscov + dh->dccph_x) * sizeof(u32);
673                 checksum_len = checksum_len < skb->len ? checksum_len :
674                                                          skb->len;
675         }
676
677         tmp = csum_partial((unsigned char *)dh, checksum_len, 0);
678         return csum_tcpudp_magic(saddr, daddr, checksum_len,
679                                  IPPROTO_DCCP, tmp);
680 }
681
682 static int dccp_v4_verify_checksum(struct sk_buff *skb,
683                                    const u32 saddr, const u32 daddr)
684 {
685         struct dccp_hdr *dh = dccp_hdr(skb);
686         int checksum_len;
687         u32 tmp;
688
689         if (dh->dccph_cscov == 0)
690                 checksum_len = skb->len;
691         else {
692                 checksum_len = (dh->dccph_cscov + dh->dccph_x) * sizeof(u32);
693                 checksum_len = checksum_len < skb->len ? checksum_len :
694                                                          skb->len;
695         }
696         tmp = csum_partial((unsigned char *)dh, checksum_len, 0);
697         return csum_tcpudp_magic(saddr, daddr, checksum_len,
698                                  IPPROTO_DCCP, tmp) == 0 ? 0 : -1;
699 }
700
701 static struct dst_entry* dccp_v4_route_skb(struct sock *sk,
702                                            struct sk_buff *skb)
703 {
704         struct rtable *rt;
705         struct flowi fl = { .oif = ((struct rtable *)skb->dst)->rt_iif,
706                             .nl_u = { .ip4_u =
707                                       { .daddr = skb->nh.iph->saddr,
708                                         .saddr = skb->nh.iph->daddr,
709                                         .tos = RT_CONN_FLAGS(sk) } },
710                             .proto = sk->sk_protocol,
711                             .uli_u = { .ports =
712                                        { .sport = dccp_hdr(skb)->dccph_dport,
713                                          .dport = dccp_hdr(skb)->dccph_sport }
714                                      }
715                           };
716
717         if (ip_route_output_flow(&rt, &fl, sk, 0)) {
718                 IP_INC_STATS_BH(IPSTATS_MIB_OUTNOROUTES);
719                 return NULL;
720         }
721
722         return &rt->u.dst;
723 }
724
725 static void dccp_v4_ctl_send_reset(struct sk_buff *rxskb)
726 {
727         int err;
728         struct dccp_hdr *rxdh = dccp_hdr(rxskb), *dh;
729         const int dccp_hdr_reset_len = sizeof(struct dccp_hdr) +
730                                        sizeof(struct dccp_hdr_ext) +
731                                        sizeof(struct dccp_hdr_reset);
732         struct sk_buff *skb;
733         struct dst_entry *dst;
734         u64 seqno;
735
736         /* Never send a reset in response to a reset. */
737         if (rxdh->dccph_type == DCCP_PKT_RESET)
738                 return;
739
740         if (((struct rtable *)rxskb->dst)->rt_type != RTN_LOCAL)
741                 return;
742
743         dst = dccp_v4_route_skb(dccp_ctl_socket->sk, rxskb);
744         if (dst == NULL)
745                 return;
746
747         skb = alloc_skb(MAX_DCCP_HEADER + 15, GFP_ATOMIC);
748         if (skb == NULL)
749                 goto out;
750
751         /* Reserve space for headers. */
752         skb_reserve(skb, MAX_DCCP_HEADER);
753         skb->dst = dst_clone(dst);
754
755         skb->h.raw = skb_push(skb, dccp_hdr_reset_len);
756         dh = dccp_hdr(skb);
757         memset(dh, 0, dccp_hdr_reset_len);
758
759         /* Build DCCP header and checksum it. */
760         dh->dccph_type     = DCCP_PKT_RESET;
761         dh->dccph_sport    = rxdh->dccph_dport;
762         dh->dccph_dport    = rxdh->dccph_sport;
763         dh->dccph_doff     = dccp_hdr_reset_len / 4;
764         dh->dccph_x        = 1;
765         dccp_hdr_reset(skb)->dccph_reset_code =
766                                 DCCP_SKB_CB(rxskb)->dccpd_reset_code;
767
768         /* See "8.3.1. Abnormal Termination" in draft-ietf-dccp-spec-11 */
769         seqno = 0;
770         if (DCCP_SKB_CB(rxskb)->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ)
771                 dccp_set_seqno(&seqno, DCCP_SKB_CB(rxskb)->dccpd_ack_seq + 1);
772
773         dccp_hdr_set_seq(dh, seqno);
774         dccp_hdr_set_ack(dccp_hdr_ack_bits(skb),
775                          DCCP_SKB_CB(rxskb)->dccpd_seq);
776
777         dh->dccph_checksum = dccp_v4_checksum(skb, rxskb->nh.iph->saddr,
778                                               rxskb->nh.iph->daddr);
779
780         bh_lock_sock(dccp_ctl_socket->sk);
781         err = ip_build_and_send_pkt(skb, dccp_ctl_socket->sk,
782                                     rxskb->nh.iph->daddr,
783                                     rxskb->nh.iph->saddr, NULL);
784         bh_unlock_sock(dccp_ctl_socket->sk);
785
786         if (err == NET_XMIT_CN || err == 0) {
787                 DCCP_INC_STATS_BH(DCCP_MIB_OUTSEGS);
788                 DCCP_INC_STATS_BH(DCCP_MIB_OUTRSTS);
789         }
790 out:
791          dst_release(dst);
792 }
793
794 int dccp_v4_do_rcv(struct sock *sk, struct sk_buff *skb)
795 {
796         struct dccp_hdr *dh = dccp_hdr(skb);
797
798         if (sk->sk_state == DCCP_OPEN) { /* Fast path */
799                 if (dccp_rcv_established(sk, skb, dh, skb->len))
800                         goto reset;
801                 return 0;
802         }
803
804         /*
805          *  Step 3: Process LISTEN state
806          *     If S.state == LISTEN,
807          *        If P.type == Request or P contains a valid Init Cookie
808          *              option,
809          *           * Must scan the packet's options to check for an Init
810          *              Cookie.  Only the Init Cookie is processed here,
811          *              however; other options are processed in Step 8.  This
812          *              scan need only be performed if the endpoint uses Init
813          *              Cookies *
814          *           * Generate a new socket and switch to that socket *
815          *           Set S := new socket for this port pair
816          *           S.state = RESPOND
817          *           Choose S.ISS (initial seqno) or set from Init Cookie
818          *           Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookie
819          *           Continue with S.state == RESPOND
820          *           * A Response packet will be generated in Step 11 *
821          *        Otherwise,
822          *           Generate Reset(No Connection) unless P.type == Reset
823          *           Drop packet and return
824          *
825          * NOTE: the check for the packet types is done in
826          *       dccp_rcv_state_process
827          */
828         if (sk->sk_state == DCCP_LISTEN) {
829                 struct sock *nsk = dccp_v4_hnd_req(sk, skb);
830
831                 if (nsk == NULL)
832                         goto discard;
833
834                 if (nsk != sk) {
835                         if (dccp_child_process(sk, nsk, skb))
836                                 goto reset;
837                         return 0;
838                 }
839         }
840
841         if (dccp_rcv_state_process(sk, skb, dh, skb->len))
842                 goto reset;
843         return 0;
844
845 reset:
846         dccp_v4_ctl_send_reset(skb);
847 discard:
848         kfree_skb(skb);
849         return 0;
850 }
851
852 EXPORT_SYMBOL_GPL(dccp_v4_do_rcv);
853
854 int dccp_invalid_packet(struct sk_buff *skb)
855 {
856         const struct dccp_hdr *dh;
857
858         if (skb->pkt_type != PACKET_HOST)
859                 return 1;
860
861         if (!pskb_may_pull(skb, sizeof(struct dccp_hdr))) {
862                 LIMIT_NETDEBUG(KERN_WARNING "DCCP: pskb_may_pull failed\n");
863                 return 1;
864         }
865
866         dh = dccp_hdr(skb);
867
868         /* If the packet type is not understood, drop packet and return */
869         if (dh->dccph_type >= DCCP_PKT_INVALID) {
870                 LIMIT_NETDEBUG(KERN_WARNING "DCCP: invalid packet type\n");
871                 return 1;
872         }
873
874         /*
875          * If P.Data Offset is too small for packet type, or too large for
876          * packet, drop packet and return
877          */
878         if (dh->dccph_doff < dccp_hdr_len(skb) / sizeof(u32)) {
879                 LIMIT_NETDEBUG(KERN_WARNING "DCCP: P.Data Offset(%u) "
880                                             "too small 1\n",
881                                dh->dccph_doff);
882                 return 1;
883         }
884
885         if (!pskb_may_pull(skb, dh->dccph_doff * sizeof(u32))) {
886                 LIMIT_NETDEBUG(KERN_WARNING "DCCP: P.Data Offset(%u) "
887                                             "too small 2\n",
888                                dh->dccph_doff);
889                 return 1;
890         }
891
892         dh = dccp_hdr(skb);
893
894         /*
895          * If P.type is not Data, Ack, or DataAck and P.X == 0 (the packet
896          * has short sequence numbers), drop packet and return
897          */
898         if (dh->dccph_x == 0 &&
899             dh->dccph_type != DCCP_PKT_DATA &&
900             dh->dccph_type != DCCP_PKT_ACK &&
901             dh->dccph_type != DCCP_PKT_DATAACK) {
902                 LIMIT_NETDEBUG(KERN_WARNING "DCCP: P.type (%s) not Data, Ack "
903                                             "nor DataAck and P.X == 0\n",
904                                dccp_packet_name(dh->dccph_type));
905                 return 1;
906         }
907
908         return 0;
909 }
910
911 EXPORT_SYMBOL_GPL(dccp_invalid_packet);
912
913 /* this is called when real data arrives */
914 int dccp_v4_rcv(struct sk_buff *skb)
915 {
916         const struct dccp_hdr *dh;
917         struct sock *sk;
918
919         /* Step 1: Check header basics: */
920
921         if (dccp_invalid_packet(skb))
922                 goto discard_it;
923
924         /* If the header checksum is incorrect, drop packet and return */
925         if (dccp_v4_verify_checksum(skb, skb->nh.iph->saddr,
926                                     skb->nh.iph->daddr) < 0) {
927                 LIMIT_NETDEBUG(KERN_WARNING "%s: incorrect header checksum\n",
928                                __FUNCTION__);
929                 goto discard_it;
930         }
931
932         dh = dccp_hdr(skb);
933
934         DCCP_SKB_CB(skb)->dccpd_seq  = dccp_hdr_seq(skb);
935         DCCP_SKB_CB(skb)->dccpd_type = dh->dccph_type;
936
937         dccp_pr_debug("%8.8s "
938                       "src=%u.%u.%u.%u@%-5d "
939                       "dst=%u.%u.%u.%u@%-5d seq=%llu",
940                       dccp_packet_name(dh->dccph_type),
941                       NIPQUAD(skb->nh.iph->saddr), ntohs(dh->dccph_sport),
942                       NIPQUAD(skb->nh.iph->daddr), ntohs(dh->dccph_dport),
943                       (unsigned long long) DCCP_SKB_CB(skb)->dccpd_seq);
944
945         if (dccp_packet_without_ack(skb)) {
946                 DCCP_SKB_CB(skb)->dccpd_ack_seq = DCCP_PKT_WITHOUT_ACK_SEQ;
947                 dccp_pr_debug_cat("\n");
948         } else {
949                 DCCP_SKB_CB(skb)->dccpd_ack_seq = dccp_hdr_ack_seq(skb);
950                 dccp_pr_debug_cat(", ack=%llu\n",
951                                   (unsigned long long)
952                                   DCCP_SKB_CB(skb)->dccpd_ack_seq);
953         }
954
955         /* Step 2:
956          *      Look up flow ID in table and get corresponding socket */
957         sk = __inet_lookup(&dccp_hashinfo,
958                            skb->nh.iph->saddr, dh->dccph_sport,
959                            skb->nh.iph->daddr, ntohs(dh->dccph_dport),
960                            inet_iif(skb));
961
962         /* 
963          * Step 2:
964          *      If no socket ...
965          *              Generate Reset(No Connection) unless P.type == Reset
966          *              Drop packet and return
967          */
968         if (sk == NULL) {
969                 dccp_pr_debug("failed to look up flow ID in table and "
970                               "get corresponding socket\n");
971                 goto no_dccp_socket;
972         }
973
974         /* 
975          * Step 2:
976          *      ... or S.state == TIMEWAIT,
977          *              Generate Reset(No Connection) unless P.type == Reset
978          *              Drop packet and return
979          */
980                
981         if (sk->sk_state == DCCP_TIME_WAIT) {
982                 dccp_pr_debug("sk->sk_state == DCCP_TIME_WAIT: "
983                               "do_time_wait\n");
984                 goto do_time_wait;
985         }
986
987         if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb))
988                 goto discard_and_relse;
989         nf_reset(skb);
990
991         return sk_receive_skb(sk, skb);
992
993 no_dccp_socket:
994         if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb))
995                 goto discard_it;
996         /*
997          * Step 2:
998          *              Generate Reset(No Connection) unless P.type == Reset
999          *              Drop packet and return
1000          */
1001         if (dh->dccph_type != DCCP_PKT_RESET) {
1002                 DCCP_SKB_CB(skb)->dccpd_reset_code =
1003                                         DCCP_RESET_CODE_NO_CONNECTION;
1004                 dccp_v4_ctl_send_reset(skb);
1005         }
1006
1007 discard_it:
1008         /* Discard frame. */
1009         kfree_skb(skb);
1010         return 0;
1011
1012 discard_and_relse:
1013         sock_put(sk);
1014         goto discard_it;
1015
1016 do_time_wait:
1017         inet_twsk_put((struct inet_timewait_sock *)sk);
1018         goto no_dccp_socket;
1019 }
1020
1021 struct inet_connection_sock_af_ops dccp_ipv4_af_ops = {
1022         .queue_xmit     = ip_queue_xmit,
1023         .send_check     = dccp_v4_send_check,
1024         .rebuild_header = inet_sk_rebuild_header,
1025         .conn_request   = dccp_v4_conn_request,
1026         .syn_recv_sock  = dccp_v4_request_recv_sock,
1027         .net_header_len = sizeof(struct iphdr),
1028         .setsockopt     = ip_setsockopt,
1029         .getsockopt     = ip_getsockopt,
1030         .addr2sockaddr  = inet_csk_addr2sockaddr,
1031         .sockaddr_len   = sizeof(struct sockaddr_in),
1032 };
1033
1034 int dccp_v4_init_sock(struct sock *sk)
1035 {
1036         struct dccp_sock *dp = dccp_sk(sk);
1037         struct inet_connection_sock *icsk = inet_csk(sk);
1038         static int dccp_ctl_socket_init = 1;
1039
1040         dccp_options_init(&dp->dccps_options);
1041         do_gettimeofday(&dp->dccps_epoch);
1042
1043         if (dp->dccps_options.dccpo_send_ack_vector) {
1044                 dp->dccps_hc_rx_ackvec = dccp_ackvec_alloc(DCCP_MAX_ACKVEC_LEN,
1045                                                            GFP_KERNEL);
1046                 if (dp->dccps_hc_rx_ackvec == NULL)
1047                         return -ENOMEM;
1048         }
1049
1050         /*
1051          * FIXME: We're hardcoding the CCID, and doing this at this point makes
1052          * the listening (master) sock get CCID control blocks, which is not
1053          * necessary, but for now, to not mess with the test userspace apps,
1054          * lets leave it here, later the real solution is to do this in a
1055          * setsockopt(CCIDs-I-want/accept). -acme
1056          */
1057         if (likely(!dccp_ctl_socket_init)) {
1058                 dp->dccps_hc_rx_ccid = ccid_init(dp->dccps_options.dccpo_rx_ccid,
1059                                                  sk);
1060                 dp->dccps_hc_tx_ccid = ccid_init(dp->dccps_options.dccpo_tx_ccid,
1061                                                  sk);
1062                 if (dp->dccps_hc_rx_ccid == NULL ||
1063                     dp->dccps_hc_tx_ccid == NULL) {
1064                         ccid_exit(dp->dccps_hc_rx_ccid, sk);
1065                         ccid_exit(dp->dccps_hc_tx_ccid, sk);
1066                         if (dp->dccps_options.dccpo_send_ack_vector) {
1067                                 dccp_ackvec_free(dp->dccps_hc_rx_ackvec);
1068                                 dp->dccps_hc_rx_ackvec = NULL;
1069                         }
1070                         dp->dccps_hc_rx_ccid = dp->dccps_hc_tx_ccid = NULL;
1071                         return -ENOMEM;
1072                 }
1073         } else
1074                 dccp_ctl_socket_init = 0;
1075
1076         dccp_init_xmit_timers(sk);
1077         icsk->icsk_rto = DCCP_TIMEOUT_INIT;
1078         sk->sk_state = DCCP_CLOSED;
1079         sk->sk_write_space = dccp_write_space;
1080         icsk->icsk_af_ops = &dccp_ipv4_af_ops;
1081         icsk->icsk_sync_mss = dccp_sync_mss;
1082         dp->dccps_mss_cache = 536;
1083         dp->dccps_role = DCCP_ROLE_UNDEFINED;
1084         dp->dccps_service = DCCP_SERVICE_INVALID_VALUE;
1085
1086         return 0;
1087 }
1088
1089 EXPORT_SYMBOL_GPL(dccp_v4_init_sock);
1090
1091 int dccp_v4_destroy_sock(struct sock *sk)
1092 {
1093         struct dccp_sock *dp = dccp_sk(sk);
1094
1095         /*
1096          * DCCP doesn't use sk_write_queue, just sk_send_head
1097          * for retransmissions
1098          */
1099         if (sk->sk_send_head != NULL) {
1100                 kfree_skb(sk->sk_send_head);
1101                 sk->sk_send_head = NULL;
1102         }
1103
1104         /* Clean up a referenced DCCP bind bucket. */
1105         if (inet_csk(sk)->icsk_bind_hash != NULL)
1106                 inet_put_port(&dccp_hashinfo, sk);
1107
1108         kfree(dp->dccps_service_list);
1109         dp->dccps_service_list = NULL;
1110
1111         ccid_hc_rx_exit(dp->dccps_hc_rx_ccid, sk);
1112         ccid_hc_tx_exit(dp->dccps_hc_tx_ccid, sk);
1113         if (dp->dccps_options.dccpo_send_ack_vector) {
1114                 dccp_ackvec_free(dp->dccps_hc_rx_ackvec);
1115                 dp->dccps_hc_rx_ackvec = NULL;
1116         }
1117         ccid_exit(dp->dccps_hc_rx_ccid, sk);
1118         ccid_exit(dp->dccps_hc_tx_ccid, sk);
1119         dp->dccps_hc_rx_ccid = dp->dccps_hc_tx_ccid = NULL;
1120
1121         return 0;
1122 }
1123
1124 EXPORT_SYMBOL_GPL(dccp_v4_destroy_sock);
1125
1126 static void dccp_v4_reqsk_destructor(struct request_sock *req)
1127 {
1128         kfree(inet_rsk(req)->opt);
1129 }
1130
1131 static struct request_sock_ops dccp_request_sock_ops = {
1132         .family         = PF_INET,
1133         .obj_size       = sizeof(struct dccp_request_sock),
1134         .rtx_syn_ack    = dccp_v4_send_response,
1135         .send_ack       = dccp_v4_reqsk_send_ack,
1136         .destructor     = dccp_v4_reqsk_destructor,
1137         .send_reset     = dccp_v4_ctl_send_reset,
1138 };
1139
1140 static struct timewait_sock_ops dccp_timewait_sock_ops = {
1141         .twsk_obj_size  = sizeof(struct inet_timewait_sock),
1142 };
1143
1144 struct proto dccp_prot = {
1145         .name                   = "DCCP",
1146         .owner                  = THIS_MODULE,
1147         .close                  = dccp_close,
1148         .connect                = dccp_v4_connect,
1149         .disconnect             = dccp_disconnect,
1150         .ioctl                  = dccp_ioctl,
1151         .init                   = dccp_v4_init_sock,
1152         .setsockopt             = dccp_setsockopt,
1153         .getsockopt             = dccp_getsockopt,
1154         .sendmsg                = dccp_sendmsg,
1155         .recvmsg                = dccp_recvmsg,
1156         .backlog_rcv            = dccp_v4_do_rcv,
1157         .hash                   = dccp_v4_hash,
1158         .unhash                 = dccp_unhash,
1159         .accept                 = inet_csk_accept,
1160         .get_port               = dccp_v4_get_port,
1161         .shutdown               = dccp_shutdown,
1162         .destroy                = dccp_v4_destroy_sock,
1163         .orphan_count           = &dccp_orphan_count,
1164         .max_header             = MAX_DCCP_HEADER,
1165         .obj_size               = sizeof(struct dccp_sock),
1166         .rsk_prot               = &dccp_request_sock_ops,
1167         .twsk_prot              = &dccp_timewait_sock_ops,
1168 };
1169
1170 EXPORT_SYMBOL_GPL(dccp_prot);