[DCCP]: Just reflow the source code to fit in 80 columns
[linux-3.10.git] / net / dccp / input.c
1 /*
2  *  net/dccp/input.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/skbuff.h>
16
17 #include <net/sock.h>
18
19 #include "ccid.h"
20 #include "dccp.h"
21
22 static void dccp_fin(struct sock *sk, struct sk_buff *skb)
23 {
24         sk->sk_shutdown |= RCV_SHUTDOWN;
25         sock_set_flag(sk, SOCK_DONE);
26         __skb_pull(skb, dccp_hdr(skb)->dccph_doff * 4);
27         __skb_queue_tail(&sk->sk_receive_queue, skb);
28         skb_set_owner_r(skb, sk);
29         sk->sk_data_ready(sk, 0);
30 }
31
32 static void dccp_rcv_close(struct sock *sk, struct sk_buff *skb)
33 {
34         switch (sk->sk_state) {
35         case DCCP_PARTOPEN:
36         case DCCP_OPEN:
37                 dccp_v4_send_reset(sk, DCCP_RESET_CODE_CLOSED);
38                 dccp_fin(sk, skb);
39                 dccp_set_state(sk, DCCP_CLOSED);
40                 break;
41         }
42 }
43
44 static void dccp_rcv_closereq(struct sock *sk, struct sk_buff *skb)
45 {
46         /*
47          *   Step 7: Check for unexpected packet types
48          *      If (S.is_server and P.type == CloseReq)
49          *        Send Sync packet acknowledging P.seqno
50          *        Drop packet and return
51          */
52         if (dccp_sk(sk)->dccps_role != DCCP_ROLE_CLIENT) {
53                 dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq);
54                 return;
55         }
56
57         switch (sk->sk_state) {
58         case DCCP_PARTOPEN:
59         case DCCP_OPEN:
60                 dccp_set_state(sk, DCCP_CLOSING);
61                 dccp_send_close(sk);
62                 break;
63         }
64 }
65
66 static inline void dccp_event_ack_recv(struct sock *sk, struct sk_buff *skb)
67 {
68         struct dccp_sock *dp = dccp_sk(sk);
69
70         if (dp->dccps_options.dccpo_send_ack_vector)
71                 dccp_ackpkts_check_rcv_ackno(dp->dccps_hc_rx_ackpkts, sk,
72                                              DCCP_SKB_CB(skb)->dccpd_ack_seq);
73 }
74
75 static int dccp_check_seqno(struct sock *sk, struct sk_buff *skb)
76 {
77         const struct dccp_hdr *dh = dccp_hdr(skb);
78         struct dccp_sock *dp = dccp_sk(sk);
79         u64 lswl = dp->dccps_swl;
80         u64 lawl = dp->dccps_awl;
81
82         /*
83          *   Step 5: Prepare sequence numbers for Sync
84          *     If P.type == Sync or P.type == SyncAck,
85          *        If S.AWL <= P.ackno <= S.AWH and P.seqno >= S.SWL,
86          *           / * P is valid, so update sequence number variables
87          *               accordingly.  After this update, P will pass the tests
88          *               in Step 6.  A SyncAck is generated if necessary in
89          *               Step 15 * /
90          *           Update S.GSR, S.SWL, S.SWH
91          *        Otherwise,
92          *           Drop packet and return
93          */
94         if (dh->dccph_type == DCCP_PKT_SYNC || 
95             dh->dccph_type == DCCP_PKT_SYNCACK) {
96                 if (between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,
97                               dp->dccps_awl, dp->dccps_awh) &&
98                     !before48(DCCP_SKB_CB(skb)->dccpd_seq, dp->dccps_swl))
99                         dccp_update_gsr(sk, DCCP_SKB_CB(skb)->dccpd_seq);
100                 else
101                         return -1;
102         /*
103          *   Step 6: Check sequence numbers
104          *      Let LSWL = S.SWL and LAWL = S.AWL
105          *      If P.type == CloseReq or P.type == Close or P.type == Reset,
106          *        LSWL := S.GSR + 1, LAWL := S.GAR
107          *      If LSWL <= P.seqno <= S.SWH
108          *           and (P.ackno does not exist or LAWL <= P.ackno <= S.AWH),
109          *        Update S.GSR, S.SWL, S.SWH
110          *        If P.type != Sync,
111          *           Update S.GAR
112          *      Otherwise,
113          *        Send Sync packet acknowledging P.seqno
114          *        Drop packet and return
115          */
116         } else if (dh->dccph_type == DCCP_PKT_CLOSEREQ ||
117                    dh->dccph_type == DCCP_PKT_CLOSE ||
118                    dh->dccph_type == DCCP_PKT_RESET) {
119                 lswl = dp->dccps_gsr;
120                 dccp_inc_seqno(&lswl);
121                 lawl = dp->dccps_gar;
122         }
123
124         if (between48(DCCP_SKB_CB(skb)->dccpd_seq, lswl, dp->dccps_swh) &&
125             (DCCP_SKB_CB(skb)->dccpd_ack_seq == DCCP_PKT_WITHOUT_ACK_SEQ ||
126              between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,
127                        lawl, dp->dccps_awh))) {
128                 dccp_update_gsr(sk, DCCP_SKB_CB(skb)->dccpd_seq);
129
130                 if (dh->dccph_type != DCCP_PKT_SYNC &&
131                     (DCCP_SKB_CB(skb)->dccpd_ack_seq !=
132                      DCCP_PKT_WITHOUT_ACK_SEQ))
133                         dp->dccps_gar = DCCP_SKB_CB(skb)->dccpd_ack_seq;
134         } else {
135                 dccp_pr_debug("Step 6 failed, sending SYNC...\n");
136                 dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq);
137                 return -1;
138         }
139
140         return 0;
141 }
142
143 int dccp_rcv_established(struct sock *sk, struct sk_buff *skb,
144                          const struct dccp_hdr *dh, const unsigned len)
145 {
146         struct dccp_sock *dp = dccp_sk(sk);
147
148         if (dccp_check_seqno(sk, skb))
149                 goto discard;
150
151         if (dccp_parse_options(sk, skb))
152                 goto discard;
153
154         if (DCCP_SKB_CB(skb)->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ)
155                 dccp_event_ack_recv(sk, skb);
156
157         /*
158          * FIXME: check ECN to see if we should use
159          * DCCP_ACKPKTS_STATE_ECN_MARKED
160          */
161         if (dp->dccps_options.dccpo_send_ack_vector) {
162                 struct dccp_ackpkts *ap = dp->dccps_hc_rx_ackpkts;
163
164                 if (dccp_ackpkts_add(dp->dccps_hc_rx_ackpkts,
165                                      DCCP_SKB_CB(skb)->dccpd_seq,
166                                      DCCP_ACKPKTS_STATE_RECEIVED)) {
167                         LIMIT_NETDEBUG(KERN_INFO "DCCP: acknowledgeable "
168                                                  "packets buffer full!\n");
169                         ap->dccpap_ack_seqno = DCCP_MAX_SEQNO + 1;
170                         inet_csk_schedule_ack(sk);
171                         inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
172                                                   TCP_DELACK_MIN,
173                                                   DCCP_RTO_MAX);
174                         goto discard;
175                 }
176
177                 /*
178                  * FIXME: this activation is probably wrong, have to study more
179                  * TCP delack machinery and how it fits into DCCP draft, but
180                  * for now it kinda "works" 8)
181                  */
182                 if (!inet_csk_ack_scheduled(sk)) {
183                         inet_csk_schedule_ack(sk);
184                         inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK, 5 * HZ,
185                                                   DCCP_RTO_MAX);
186                 }
187         }
188
189         ccid_hc_rx_packet_recv(dp->dccps_hc_rx_ccid, sk, skb);
190         ccid_hc_tx_packet_recv(dp->dccps_hc_tx_ccid, sk, skb);
191
192         switch (dccp_hdr(skb)->dccph_type) {
193         case DCCP_PKT_DATAACK:
194         case DCCP_PKT_DATA:
195                 /*
196                  * FIXME: check if sk_receive_queue is full, schedule DATA_DROPPED
197                  * option if it is.
198                  */
199                 __skb_pull(skb, dh->dccph_doff * 4);
200                 __skb_queue_tail(&sk->sk_receive_queue, skb);
201                 skb_set_owner_r(skb, sk);
202                 sk->sk_data_ready(sk, 0);
203                 return 0;
204         case DCCP_PKT_ACK:
205                 goto discard;
206         case DCCP_PKT_RESET:
207                 /*
208                  *  Step 9: Process Reset
209                  *      If P.type == Reset,
210                  *              Tear down connection
211                  *              S.state := TIMEWAIT
212                  *              Set TIMEWAIT timer
213                  *              Drop packet and return
214                 */
215                 dccp_fin(sk, skb);
216                 dccp_time_wait(sk, DCCP_TIME_WAIT, 0);
217                 return 0;
218         case DCCP_PKT_CLOSEREQ:
219                 dccp_rcv_closereq(sk, skb);
220                 goto discard;
221         case DCCP_PKT_CLOSE:
222                 dccp_rcv_close(sk, skb);
223                 return 0;
224         case DCCP_PKT_REQUEST:
225                 /* Step 7 
226                  *   or (S.is_server and P.type == Response)
227                  *   or (S.is_client and P.type == Request)
228                  *   or (S.state >= OPEN and P.type == Request
229                  *      and P.seqno >= S.OSR)
230                  *    or (S.state >= OPEN and P.type == Response
231                  *      and P.seqno >= S.OSR)
232                  *    or (S.state == RESPOND and P.type == Data),
233                  *  Send Sync packet acknowledging P.seqno
234                  *  Drop packet and return
235                  */
236                 if (dp->dccps_role != DCCP_ROLE_LISTEN)
237                         goto send_sync;
238                 goto check_seq;
239         case DCCP_PKT_RESPONSE:
240                 if (dp->dccps_role != DCCP_ROLE_CLIENT)
241                         goto send_sync;
242 check_seq:
243                 if (!before48(DCCP_SKB_CB(skb)->dccpd_seq, dp->dccps_osr)) {
244 send_sync:
245                         dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq);
246                 }
247                 break;
248         }
249
250         DCCP_INC_STATS_BH(DCCP_MIB_INERRS);
251 discard:
252         __kfree_skb(skb);
253         return 0;
254 }
255
256 static int dccp_rcv_request_sent_state_process(struct sock *sk,
257                                                struct sk_buff *skb,
258                                                const struct dccp_hdr *dh,
259                                                const unsigned len)
260 {
261         /* 
262          *  Step 4: Prepare sequence numbers in REQUEST
263          *     If S.state == REQUEST,
264          *        If (P.type == Response or P.type == Reset)
265          *              and S.AWL <= P.ackno <= S.AWH,
266          *           / * Set sequence number variables corresponding to the
267          *              other endpoint, so P will pass the tests in Step 6 * /
268          *           Set S.GSR, S.ISR, S.SWL, S.SWH
269          *           / * Response processing continues in Step 10; Reset
270          *              processing continues in Step 9 * /
271         */
272         if (dh->dccph_type == DCCP_PKT_RESPONSE) {
273                 const struct inet_connection_sock *icsk = inet_csk(sk);
274                 struct dccp_sock *dp = dccp_sk(sk);
275
276                 /* Stop the REQUEST timer */
277                 inet_csk_clear_xmit_timer(sk, ICSK_TIME_RETRANS);
278                 BUG_TRAP(sk->sk_send_head != NULL);
279                 __kfree_skb(sk->sk_send_head);
280                 sk->sk_send_head = NULL;
281
282                 if (!between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,
283                                dp->dccps_awl, dp->dccps_awh)) {
284                         dccp_pr_debug("invalid ackno: S.AWL=%llu, "
285                                       "P.ackno=%llu, S.AWH=%llu \n",
286                                       (unsigned long long)dp->dccps_awl,
287                            (unsigned long long)DCCP_SKB_CB(skb)->dccpd_ack_seq,
288                                       (unsigned long long)dp->dccps_awh);
289                         goto out_invalid_packet;
290                 }
291
292                 dp->dccps_isr = DCCP_SKB_CB(skb)->dccpd_seq;
293                 dccp_update_gsr(sk, DCCP_SKB_CB(skb)->dccpd_seq);
294
295                 if (ccid_hc_rx_init(dp->dccps_hc_rx_ccid, sk) != 0 ||
296                     ccid_hc_tx_init(dp->dccps_hc_tx_ccid, sk) != 0) {
297                         ccid_hc_rx_exit(dp->dccps_hc_rx_ccid, sk);
298                         ccid_hc_tx_exit(dp->dccps_hc_tx_ccid, sk);
299                         /* FIXME: send appropriate RESET code */
300                         goto out_invalid_packet;
301                 }
302
303                 dccp_sync_mss(sk, dp->dccps_pmtu_cookie);
304
305                 /*
306                  *    Step 10: Process REQUEST state (second part)
307                  *       If S.state == REQUEST,
308                  *        / * If we get here, P is a valid Response from the
309                  *            server (see Step 4), and we should move to
310                  *            PARTOPEN state. PARTOPEN means send an Ack,
311                  *            don't send Data packets, retransmit Acks
312                  *            periodically, and always include any Init Cookie
313                  *            from the Response * /
314                  *        S.state := PARTOPEN
315                  *        Set PARTOPEN timer
316                  *        Continue with S.state == PARTOPEN
317                  *        / * Step 12 will send the Ack completing the
318                  *            three-way handshake * /
319                  */
320                 dccp_set_state(sk, DCCP_PARTOPEN);
321
322                 /* Make sure socket is routed, for correct metrics. */
323                 inet_sk_rebuild_header(sk);
324
325                 if (!sock_flag(sk, SOCK_DEAD)) {
326                         sk->sk_state_change(sk);
327                         sk_wake_async(sk, 0, POLL_OUT);
328                 }
329
330                 if (sk->sk_write_pending || icsk->icsk_ack.pingpong ||
331                     icsk->icsk_accept_queue.rskq_defer_accept) {
332                         /* Save one ACK. Data will be ready after
333                          * several ticks, if write_pending is set.
334                          *
335                          * It may be deleted, but with this feature tcpdumps
336                          * look so _wonderfully_ clever, that I was not able
337                          * to stand against the temptation 8)     --ANK
338                          */
339                         /*
340                          * OK, in DCCP we can as well do a similar trick, its
341                          * even in the draft, but there is no need for us to
342                          * schedule an ack here, as dccp_sendmsg does this for
343                          * us, also stated in the draft. -acme
344                          */
345                         __kfree_skb(skb);
346                         return 0;
347                 } 
348                 dccp_send_ack(sk);
349                 return -1;
350         }
351
352 out_invalid_packet:
353         return 1; /* dccp_v4_do_rcv will send a reset, but...
354                      FIXME: the reset code should be
355                             DCCP_RESET_CODE_PACKET_ERROR */
356 }
357
358 static int dccp_rcv_respond_partopen_state_process(struct sock *sk,
359                                                    struct sk_buff *skb,
360                                                    const struct dccp_hdr *dh,
361                                                    const unsigned len)
362 {
363         int queued = 0;
364
365         switch (dh->dccph_type) {
366         case DCCP_PKT_RESET:
367                 inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK);
368                 break;
369         case DCCP_PKT_DATAACK:
370         case DCCP_PKT_ACK:
371                 /*
372                  * FIXME: we should be reseting the PARTOPEN (DELACK) timer
373                  * here but only if we haven't used the DELACK timer for
374                  * something else, like sending a delayed ack for a TIMESTAMP
375                  * echo, etc, for now were not clearing it, sending an extra
376                  * ACK when there is nothing else to do in DELACK is not a big
377                  * deal after all.
378                  */
379
380                 /* Stop the PARTOPEN timer */
381                 if (sk->sk_state == DCCP_PARTOPEN)
382                         inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK);
383
384                 dccp_sk(sk)->dccps_osr = DCCP_SKB_CB(skb)->dccpd_seq;
385                 dccp_set_state(sk, DCCP_OPEN);
386
387                 if (dh->dccph_type == DCCP_PKT_DATAACK) {
388                         dccp_rcv_established(sk, skb, dh, len);
389                         queued = 1; /* packet was queued
390                                        (by dccp_rcv_established) */
391                 }
392                 break;
393         }
394
395         return queued;
396 }
397
398 int dccp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
399                            struct dccp_hdr *dh, unsigned len)
400 {
401         struct dccp_sock *dp = dccp_sk(sk);
402         const int old_state = sk->sk_state;
403         int queued = 0;
404
405         if (sk->sk_state != DCCP_LISTEN && sk->sk_state != DCCP_REQUESTING) {
406                 if (dccp_check_seqno(sk, skb))
407                         goto discard;
408
409                 /*
410                  * Step 8: Process options and mark acknowledgeable
411                  */
412                 if (dccp_parse_options(sk, skb))
413                         goto discard;
414
415                 if (DCCP_SKB_CB(skb)->dccpd_ack_seq !=
416                     DCCP_PKT_WITHOUT_ACK_SEQ)
417                         dccp_event_ack_recv(sk, skb);
418
419                 ccid_hc_rx_packet_recv(dp->dccps_hc_rx_ccid, sk, skb);
420                 ccid_hc_tx_packet_recv(dp->dccps_hc_tx_ccid, sk, skb);
421
422                 /*
423                  * FIXME: check ECN to see if we should use
424                  * DCCP_ACKPKTS_STATE_ECN_MARKED
425                  */
426                 if (dp->dccps_options.dccpo_send_ack_vector) {
427                         if (dccp_ackpkts_add(dp->dccps_hc_rx_ackpkts,
428                                              DCCP_SKB_CB(skb)->dccpd_seq,
429                                              DCCP_ACKPKTS_STATE_RECEIVED))
430                                 goto discard;
431                         /*
432                          * FIXME: this activation is probably wrong, have to
433                          * study more TCP delack machinery and how it fits into
434                          * DCCP draft, but for now it kinda "works" 8)
435                          */
436                         if ((dp->dccps_hc_rx_ackpkts->dccpap_ack_seqno ==
437                              DCCP_MAX_SEQNO + 1) &&
438                             !inet_csk_ack_scheduled(sk)) {
439                                 inet_csk_schedule_ack(sk);
440                                 inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
441                                                           TCP_DELACK_MIN,
442                                                           DCCP_RTO_MAX);
443                         }
444                 }
445         }
446
447         /*
448          *  Step 9: Process Reset
449          *      If P.type == Reset,
450          *              Tear down connection
451          *              S.state := TIMEWAIT
452          *              Set TIMEWAIT timer
453          *              Drop packet and return
454         */
455         if (dh->dccph_type == DCCP_PKT_RESET) {
456                 /*
457                  * Queue the equivalent of TCP fin so that dccp_recvmsg
458                  * exits the loop
459                  */
460                 dccp_fin(sk, skb);
461                 dccp_time_wait(sk, DCCP_TIME_WAIT, 0);
462                 return 0;
463                 /*
464                  *   Step 7: Check for unexpected packet types
465                  *      If (S.is_server and P.type == CloseReq)
466                  *          or (S.is_server and P.type == Response)
467                  *          or (S.is_client and P.type == Request)
468                  *          or (S.state == RESPOND and P.type == Data),
469                  *        Send Sync packet acknowledging P.seqno
470                  *        Drop packet and return
471                  */
472         } else if ((dp->dccps_role != DCCP_ROLE_CLIENT &&
473                     (dh->dccph_type == DCCP_PKT_RESPONSE ||
474                      dh->dccph_type == DCCP_PKT_CLOSEREQ)) ||
475                     (dp->dccps_role == DCCP_ROLE_CLIENT &&
476                      dh->dccph_type == DCCP_PKT_REQUEST) ||
477                     (sk->sk_state == DCCP_RESPOND &&
478                      dh->dccph_type == DCCP_PKT_DATA)) {
479                 dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq);
480                 goto discard;
481         }
482
483         switch (sk->sk_state) {
484         case DCCP_CLOSED:
485                 return 1;
486
487         case DCCP_LISTEN:
488                 if (dh->dccph_type == DCCP_PKT_ACK ||
489                     dh->dccph_type == DCCP_PKT_DATAACK)
490                         return 1;
491
492                 if (dh->dccph_type == DCCP_PKT_RESET)
493                         goto discard;
494
495                 if (dh->dccph_type == DCCP_PKT_REQUEST) {
496                         if (dccp_v4_conn_request(sk, skb) < 0)
497                                 return 1;
498
499                         /* FIXME: do congestion control initialization */
500                         goto discard;
501                 }
502                 goto discard;
503
504         case DCCP_REQUESTING:
505                 /* FIXME: do congestion control initialization */
506
507                 queued = dccp_rcv_request_sent_state_process(sk, skb, dh, len);
508                 if (queued >= 0)
509                         return queued;
510
511                 __kfree_skb(skb);
512                 return 0;
513
514         case DCCP_RESPOND:
515         case DCCP_PARTOPEN:
516                 queued = dccp_rcv_respond_partopen_state_process(sk, skb,
517                                                                  dh, len);
518                 break;
519         }
520
521         if (dh->dccph_type == DCCP_PKT_ACK ||
522             dh->dccph_type == DCCP_PKT_DATAACK) {
523                 switch (old_state) {
524                 case DCCP_PARTOPEN:
525                         sk->sk_state_change(sk);
526                         sk_wake_async(sk, 0, POLL_OUT);
527                         break;
528                 }
529         }
530
531         if (!queued) { 
532 discard:
533                 __kfree_skb(skb);
534         }
535         return 0;
536 }