[DCCP]: Transition from PARTOPEN to OPEN when receiving DATA packets
[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 "ackvec.h"
20 #include "ccid.h"
21 #include "dccp.h"
22
23 static void dccp_fin(struct sock *sk, struct sk_buff *skb)
24 {
25         sk->sk_shutdown |= RCV_SHUTDOWN;
26         sock_set_flag(sk, SOCK_DONE);
27         __skb_pull(skb, dccp_hdr(skb)->dccph_doff * 4);
28         __skb_queue_tail(&sk->sk_receive_queue, skb);
29         skb_set_owner_r(skb, sk);
30         sk->sk_data_ready(sk, 0);
31 }
32
33 static void dccp_rcv_close(struct sock *sk, struct sk_buff *skb)
34 {
35         dccp_v4_send_reset(sk, DCCP_RESET_CODE_CLOSED);
36         dccp_fin(sk, skb);
37         dccp_set_state(sk, DCCP_CLOSED);
38         sk_wake_async(sk, 1, POLL_HUP);
39 }
40
41 static void dccp_rcv_closereq(struct sock *sk, struct sk_buff *skb)
42 {
43         /*
44          *   Step 7: Check for unexpected packet types
45          *      If (S.is_server and P.type == CloseReq)
46          *        Send Sync packet acknowledging P.seqno
47          *        Drop packet and return
48          */
49         if (dccp_sk(sk)->dccps_role != DCCP_ROLE_CLIENT) {
50                 dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq, DCCP_PKT_SYNC);
51                 return;
52         }
53
54         if (sk->sk_state != DCCP_CLOSING)
55                 dccp_set_state(sk, DCCP_CLOSING);
56         dccp_send_close(sk, 0);
57 }
58
59 static inline void dccp_event_ack_recv(struct sock *sk, struct sk_buff *skb)
60 {
61         struct dccp_sock *dp = dccp_sk(sk);
62
63         if (dp->dccps_options.dccpo_send_ack_vector)
64                 dccp_ackvec_check_rcv_ackno(dp->dccps_hc_rx_ackvec, sk,
65                                             DCCP_SKB_CB(skb)->dccpd_ack_seq);
66 }
67
68 static int dccp_check_seqno(struct sock *sk, struct sk_buff *skb)
69 {
70         const struct dccp_hdr *dh = dccp_hdr(skb);
71         struct dccp_sock *dp = dccp_sk(sk);
72         u64 lswl, lawl;
73
74         /*
75          *   Step 5: Prepare sequence numbers for Sync
76          *     If P.type == Sync or P.type == SyncAck,
77          *        If S.AWL <= P.ackno <= S.AWH and P.seqno >= S.SWL,
78          *           / * P is valid, so update sequence number variables
79          *               accordingly.  After this update, P will pass the tests
80          *               in Step 6.  A SyncAck is generated if necessary in
81          *               Step 15 * /
82          *           Update S.GSR, S.SWL, S.SWH
83          *        Otherwise,
84          *           Drop packet and return
85          */
86         if (dh->dccph_type == DCCP_PKT_SYNC || 
87             dh->dccph_type == DCCP_PKT_SYNCACK) {
88                 if (between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,
89                               dp->dccps_awl, dp->dccps_awh) &&
90                     !before48(DCCP_SKB_CB(skb)->dccpd_seq, dp->dccps_swl))
91                         dccp_update_gsr(sk, DCCP_SKB_CB(skb)->dccpd_seq);
92                 else
93                         return -1;
94         }
95         
96         /*
97          *   Step 6: Check sequence numbers
98          *      Let LSWL = S.SWL and LAWL = S.AWL
99          *      If P.type == CloseReq or P.type == Close or P.type == Reset,
100          *        LSWL := S.GSR + 1, LAWL := S.GAR
101          *      If LSWL <= P.seqno <= S.SWH
102          *           and (P.ackno does not exist or LAWL <= P.ackno <= S.AWH),
103          *        Update S.GSR, S.SWL, S.SWH
104          *        If P.type != Sync,
105          *           Update S.GAR
106          *      Otherwise,
107          *        Send Sync packet acknowledging P.seqno
108          *        Drop packet and return
109          */
110         lswl = dp->dccps_swl;
111         lawl = dp->dccps_awl;
112
113         if (dh->dccph_type == DCCP_PKT_CLOSEREQ ||
114             dh->dccph_type == DCCP_PKT_CLOSE ||
115             dh->dccph_type == DCCP_PKT_RESET) {
116                 lswl = dp->dccps_gsr;
117                 dccp_inc_seqno(&lswl);
118                 lawl = dp->dccps_gar;
119         }
120
121         if (between48(DCCP_SKB_CB(skb)->dccpd_seq, lswl, dp->dccps_swh) &&
122             (DCCP_SKB_CB(skb)->dccpd_ack_seq == DCCP_PKT_WITHOUT_ACK_SEQ ||
123              between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,
124                        lawl, dp->dccps_awh))) {
125                 dccp_update_gsr(sk, DCCP_SKB_CB(skb)->dccpd_seq);
126
127                 if (dh->dccph_type != DCCP_PKT_SYNC &&
128                     (DCCP_SKB_CB(skb)->dccpd_ack_seq !=
129                      DCCP_PKT_WITHOUT_ACK_SEQ))
130                         dp->dccps_gar = DCCP_SKB_CB(skb)->dccpd_ack_seq;
131         } else {
132                 LIMIT_NETDEBUG(KERN_WARNING "DCCP: Step 6 failed for %s packet, "
133                                             "(LSWL(%llu) <= P.seqno(%llu) <= S.SWH(%llu)) and "
134                                             "(P.ackno %s or LAWL(%llu) <= P.ackno(%llu) <= S.AWH(%llu), "
135                                             "sending SYNC...\n",
136                                dccp_packet_name(dh->dccph_type),
137                                (unsigned long long) lswl,
138                                (unsigned long long)
139                                DCCP_SKB_CB(skb)->dccpd_seq,
140                                (unsigned long long) dp->dccps_swh,
141                                (DCCP_SKB_CB(skb)->dccpd_ack_seq ==
142                                 DCCP_PKT_WITHOUT_ACK_SEQ) ? "doesn't exist" : "exists",
143                                (unsigned long long) lawl,
144                                (unsigned long long)
145                                DCCP_SKB_CB(skb)->dccpd_ack_seq,
146                                (unsigned long long) dp->dccps_awh);
147                 dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq, DCCP_PKT_SYNC);
148                 return -1;
149         }
150
151         return 0;
152 }
153
154 int dccp_rcv_established(struct sock *sk, struct sk_buff *skb,
155                          const struct dccp_hdr *dh, const unsigned len)
156 {
157         struct dccp_sock *dp = dccp_sk(sk);
158
159         if (dccp_check_seqno(sk, skb))
160                 goto discard;
161
162         if (dccp_parse_options(sk, skb))
163                 goto discard;
164
165         if (DCCP_SKB_CB(skb)->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ)
166                 dccp_event_ack_recv(sk, skb);
167
168         if (dp->dccps_options.dccpo_send_ack_vector &&
169             dccp_ackvec_add(dp->dccps_hc_rx_ackvec, sk,
170                             DCCP_SKB_CB(skb)->dccpd_seq,
171                             DCCP_ACKVEC_STATE_RECEIVED))
172                 goto discard;
173
174         ccid_hc_rx_packet_recv(dp->dccps_hc_rx_ccid, sk, skb);
175         ccid_hc_tx_packet_recv(dp->dccps_hc_tx_ccid, sk, skb);
176
177         switch (dccp_hdr(skb)->dccph_type) {
178         case DCCP_PKT_DATAACK:
179         case DCCP_PKT_DATA:
180                 /*
181                  * FIXME: check if sk_receive_queue is full, schedule DATA_DROPPED
182                  * option if it is.
183                  */
184                 __skb_pull(skb, dh->dccph_doff * 4);
185                 __skb_queue_tail(&sk->sk_receive_queue, skb);
186                 skb_set_owner_r(skb, sk);
187                 sk->sk_data_ready(sk, 0);
188                 return 0;
189         case DCCP_PKT_ACK:
190                 goto discard;
191         case DCCP_PKT_RESET:
192                 /*
193                  *  Step 9: Process Reset
194                  *      If P.type == Reset,
195                  *              Tear down connection
196                  *              S.state := TIMEWAIT
197                  *              Set TIMEWAIT timer
198                  *              Drop packet and return
199                 */
200                 dccp_fin(sk, skb);
201                 dccp_time_wait(sk, DCCP_TIME_WAIT, 0);
202                 return 0;
203         case DCCP_PKT_CLOSEREQ:
204                 dccp_rcv_closereq(sk, skb);
205                 goto discard;
206         case DCCP_PKT_CLOSE:
207                 dccp_rcv_close(sk, skb);
208                 return 0;
209         case DCCP_PKT_REQUEST:
210                 /* Step 7 
211                  *   or (S.is_server and P.type == Response)
212                  *   or (S.is_client and P.type == Request)
213                  *   or (S.state >= OPEN and P.type == Request
214                  *      and P.seqno >= S.OSR)
215                  *    or (S.state >= OPEN and P.type == Response
216                  *      and P.seqno >= S.OSR)
217                  *    or (S.state == RESPOND and P.type == Data),
218                  *  Send Sync packet acknowledging P.seqno
219                  *  Drop packet and return
220                  */
221                 if (dp->dccps_role != DCCP_ROLE_LISTEN)
222                         goto send_sync;
223                 goto check_seq;
224         case DCCP_PKT_RESPONSE:
225                 if (dp->dccps_role != DCCP_ROLE_CLIENT)
226                         goto send_sync;
227 check_seq:
228                 if (!before48(DCCP_SKB_CB(skb)->dccpd_seq, dp->dccps_osr)) {
229 send_sync:
230                         dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq,
231                                        DCCP_PKT_SYNC);
232                 }
233                 break;
234         case DCCP_PKT_SYNC:
235                 dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq,
236                                DCCP_PKT_SYNCACK);
237                 /*
238                  * From the draft:
239                  *
240                  * As with DCCP-Ack packets, DCCP-Sync and DCCP-SyncAck packets
241                  * MAY have non-zero-length application data areas, whose
242                  * contents * receivers MUST ignore.
243                  */
244                 goto discard;
245         }
246
247         DCCP_INC_STATS_BH(DCCP_MIB_INERRS);
248 discard:
249         __kfree_skb(skb);
250         return 0;
251 }
252
253 static int dccp_rcv_request_sent_state_process(struct sock *sk,
254                                                struct sk_buff *skb,
255                                                const struct dccp_hdr *dh,
256                                                const unsigned len)
257 {
258         /* 
259          *  Step 4: Prepare sequence numbers in REQUEST
260          *     If S.state == REQUEST,
261          *        If (P.type == Response or P.type == Reset)
262          *              and S.AWL <= P.ackno <= S.AWH,
263          *           / * Set sequence number variables corresponding to the
264          *              other endpoint, so P will pass the tests in Step 6 * /
265          *           Set S.GSR, S.ISR, S.SWL, S.SWH
266          *           / * Response processing continues in Step 10; Reset
267          *              processing continues in Step 9 * /
268         */
269         if (dh->dccph_type == DCCP_PKT_RESPONSE) {
270                 const struct inet_connection_sock *icsk = inet_csk(sk);
271                 struct dccp_sock *dp = dccp_sk(sk);
272
273                 /* Stop the REQUEST timer */
274                 inet_csk_clear_xmit_timer(sk, ICSK_TIME_RETRANS);
275                 BUG_TRAP(sk->sk_send_head != NULL);
276                 __kfree_skb(sk->sk_send_head);
277                 sk->sk_send_head = NULL;
278
279                 if (!between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,
280                                dp->dccps_awl, dp->dccps_awh)) {
281                         dccp_pr_debug("invalid ackno: S.AWL=%llu, "
282                                       "P.ackno=%llu, S.AWH=%llu \n",
283                                       (unsigned long long)dp->dccps_awl,
284                            (unsigned long long)DCCP_SKB_CB(skb)->dccpd_ack_seq,
285                                       (unsigned long long)dp->dccps_awh);
286                         goto out_invalid_packet;
287                 }
288
289                 dp->dccps_isr = DCCP_SKB_CB(skb)->dccpd_seq;
290                 dccp_update_gsr(sk, dp->dccps_isr);
291                 /*
292                  * SWL and AWL are initially adjusted so that they are not less than
293                  * the initial Sequence Numbers received and sent, respectively:
294                  *      SWL := max(GSR + 1 - floor(W/4), ISR),
295                  *      AWL := max(GSS - W' + 1, ISS).
296                  * These adjustments MUST be applied only at the beginning of the
297                  * connection.
298                  *
299                  * AWL was adjusted in dccp_v4_connect -acme
300                  */
301                 dccp_set_seqno(&dp->dccps_swl,
302                                max48(dp->dccps_swl, dp->dccps_isr));
303
304                 if (ccid_hc_rx_init(dp->dccps_hc_rx_ccid, sk) != 0 ||
305                     ccid_hc_tx_init(dp->dccps_hc_tx_ccid, sk) != 0) {
306                         ccid_hc_rx_exit(dp->dccps_hc_rx_ccid, sk);
307                         ccid_hc_tx_exit(dp->dccps_hc_tx_ccid, sk);
308                         /* FIXME: send appropriate RESET code */
309                         goto out_invalid_packet;
310                 }
311
312                 dccp_sync_mss(sk, dp->dccps_pmtu_cookie);
313
314                 /*
315                  *    Step 10: Process REQUEST state (second part)
316                  *       If S.state == REQUEST,
317                  *        / * If we get here, P is a valid Response from the
318                  *            server (see Step 4), and we should move to
319                  *            PARTOPEN state. PARTOPEN means send an Ack,
320                  *            don't send Data packets, retransmit Acks
321                  *            periodically, and always include any Init Cookie
322                  *            from the Response * /
323                  *        S.state := PARTOPEN
324                  *        Set PARTOPEN timer
325                  *        Continue with S.state == PARTOPEN
326                  *        / * Step 12 will send the Ack completing the
327                  *            three-way handshake * /
328                  */
329                 dccp_set_state(sk, DCCP_PARTOPEN);
330
331                 /* Make sure socket is routed, for correct metrics. */
332                 inet_sk_rebuild_header(sk);
333
334                 if (!sock_flag(sk, SOCK_DEAD)) {
335                         sk->sk_state_change(sk);
336                         sk_wake_async(sk, 0, POLL_OUT);
337                 }
338
339                 if (sk->sk_write_pending || icsk->icsk_ack.pingpong ||
340                     icsk->icsk_accept_queue.rskq_defer_accept) {
341                         /* Save one ACK. Data will be ready after
342                          * several ticks, if write_pending is set.
343                          *
344                          * It may be deleted, but with this feature tcpdumps
345                          * look so _wonderfully_ clever, that I was not able
346                          * to stand against the temptation 8)     --ANK
347                          */
348                         /*
349                          * OK, in DCCP we can as well do a similar trick, its
350                          * even in the draft, but there is no need for us to
351                          * schedule an ack here, as dccp_sendmsg does this for
352                          * us, also stated in the draft. -acme
353                          */
354                         __kfree_skb(skb);
355                         return 0;
356                 } 
357                 dccp_send_ack(sk);
358                 return -1;
359         }
360
361 out_invalid_packet:
362         /* dccp_v4_do_rcv will send a reset */
363         DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_PACKET_ERROR;
364         return 1; 
365 }
366
367 static int dccp_rcv_respond_partopen_state_process(struct sock *sk,
368                                                    struct sk_buff *skb,
369                                                    const struct dccp_hdr *dh,
370                                                    const unsigned len)
371 {
372         int queued = 0;
373
374         switch (dh->dccph_type) {
375         case DCCP_PKT_RESET:
376                 inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK);
377                 break;
378         case DCCP_PKT_DATA:
379                 if (sk->sk_state == DCCP_RESPOND)
380                         break;
381         case DCCP_PKT_DATAACK:
382         case DCCP_PKT_ACK:
383                 /*
384                  * FIXME: we should be reseting the PARTOPEN (DELACK) timer
385                  * here but only if we haven't used the DELACK timer for
386                  * something else, like sending a delayed ack for a TIMESTAMP
387                  * echo, etc, for now were not clearing it, sending an extra
388                  * ACK when there is nothing else to do in DELACK is not a big
389                  * deal after all.
390                  */
391
392                 /* Stop the PARTOPEN timer */
393                 if (sk->sk_state == DCCP_PARTOPEN)
394                         inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK);
395
396                 dccp_sk(sk)->dccps_osr = DCCP_SKB_CB(skb)->dccpd_seq;
397                 dccp_set_state(sk, DCCP_OPEN);
398
399                 if (dh->dccph_type == DCCP_PKT_DATAACK ||
400                     dh->dccph_type == DCCP_PKT_DATA) {
401                         dccp_rcv_established(sk, skb, dh, len);
402                         queued = 1; /* packet was queued
403                                        (by dccp_rcv_established) */
404                 }
405                 break;
406         }
407
408         return queued;
409 }
410
411 int dccp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
412                            struct dccp_hdr *dh, unsigned len)
413 {
414         struct dccp_sock *dp = dccp_sk(sk);
415         struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
416         const int old_state = sk->sk_state;
417         int queued = 0;
418
419         /*
420          *  Step 3: Process LISTEN state
421          *      (Continuing from dccp_v4_do_rcv and dccp_v6_do_rcv)
422          *
423          *     If S.state == LISTEN,
424          *        If P.type == Request or P contains a valid Init Cookie
425          *              option,
426          *           * Must scan the packet's options to check for an Init
427          *              Cookie.  Only the Init Cookie is processed here,
428          *              however; other options are processed in Step 8.  This
429          *              scan need only be performed if the endpoint uses Init
430          *              Cookies *
431          *           * Generate a new socket and switch to that socket *
432          *           Set S := new socket for this port pair
433          *           S.state = RESPOND
434          *           Choose S.ISS (initial seqno) or set from Init Cookie
435          *           Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookie
436          *           Continue with S.state == RESPOND
437          *           * A Response packet will be generated in Step 11 *
438          *        Otherwise,
439          *           Generate Reset(No Connection) unless P.type == Reset
440          *           Drop packet and return
441          *
442          * NOTE: the check for the packet types is done in
443          *       dccp_rcv_state_process
444          */
445         if (sk->sk_state == DCCP_LISTEN) {
446                 if (dh->dccph_type == DCCP_PKT_REQUEST) {
447                         if (dccp_v4_conn_request(sk, skb) < 0)
448                                 return 1;
449
450                         /* FIXME: do congestion control initialization */
451                         goto discard;
452                 }
453                 if (dh->dccph_type == DCCP_PKT_RESET)
454                         goto discard;
455
456                 /* Caller (dccp_v4_do_rcv) will send Reset */
457                 dcb->dccpd_reset_code = DCCP_RESET_CODE_NO_CONNECTION;
458                 return 1;
459         }
460
461         if (sk->sk_state != DCCP_REQUESTING) {
462                 if (dccp_check_seqno(sk, skb))
463                         goto discard;
464
465                 /*
466                  * Step 8: Process options and mark acknowledgeable
467                  */
468                 if (dccp_parse_options(sk, skb))
469                         goto discard;
470
471                 if (dcb->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ)
472                         dccp_event_ack_recv(sk, skb);
473
474                 ccid_hc_rx_packet_recv(dp->dccps_hc_rx_ccid, sk, skb);
475                 ccid_hc_tx_packet_recv(dp->dccps_hc_tx_ccid, sk, skb);
476
477                 if (dp->dccps_options.dccpo_send_ack_vector &&
478                     dccp_ackvec_add(dp->dccps_hc_rx_ackvec, sk,
479                                     DCCP_SKB_CB(skb)->dccpd_seq,
480                                     DCCP_ACKVEC_STATE_RECEIVED))
481                         goto discard;
482         }
483
484         /*
485          *  Step 9: Process Reset
486          *      If P.type == Reset,
487          *              Tear down connection
488          *              S.state := TIMEWAIT
489          *              Set TIMEWAIT timer
490          *              Drop packet and return
491         */
492         if (dh->dccph_type == DCCP_PKT_RESET) {
493                 /*
494                  * Queue the equivalent of TCP fin so that dccp_recvmsg
495                  * exits the loop
496                  */
497                 dccp_fin(sk, skb);
498                 dccp_time_wait(sk, DCCP_TIME_WAIT, 0);
499                 return 0;
500                 /*
501                  *   Step 7: Check for unexpected packet types
502                  *      If (S.is_server and P.type == CloseReq)
503                  *          or (S.is_server and P.type == Response)
504                  *          or (S.is_client and P.type == Request)
505                  *          or (S.state == RESPOND and P.type == Data),
506                  *        Send Sync packet acknowledging P.seqno
507                  *        Drop packet and return
508                  */
509         } else if ((dp->dccps_role != DCCP_ROLE_CLIENT &&
510                     (dh->dccph_type == DCCP_PKT_RESPONSE ||
511                      dh->dccph_type == DCCP_PKT_CLOSEREQ)) ||
512                     (dp->dccps_role == DCCP_ROLE_CLIENT &&
513                      dh->dccph_type == DCCP_PKT_REQUEST) ||
514                     (sk->sk_state == DCCP_RESPOND &&
515                      dh->dccph_type == DCCP_PKT_DATA)) {
516                 dccp_send_sync(sk, dcb->dccpd_seq, DCCP_PKT_SYNC);
517                 goto discard;
518         } else if (dh->dccph_type == DCCP_PKT_CLOSEREQ) {
519                 dccp_rcv_closereq(sk, skb);
520                 goto discard;
521         } else if (dh->dccph_type == DCCP_PKT_CLOSE) {
522                 dccp_rcv_close(sk, skb);
523                 return 0;
524         }
525
526         if (unlikely(dh->dccph_type == DCCP_PKT_SYNC)) {
527                 dccp_send_sync(sk, dcb->dccpd_seq, DCCP_PKT_SYNCACK);
528                 goto discard;
529         }
530
531         switch (sk->sk_state) {
532         case DCCP_CLOSED:
533                 dcb->dccpd_reset_code = DCCP_RESET_CODE_NO_CONNECTION;
534                 return 1;
535
536         case DCCP_REQUESTING:
537                 /* FIXME: do congestion control initialization */
538
539                 queued = dccp_rcv_request_sent_state_process(sk, skb, dh, len);
540                 if (queued >= 0)
541                         return queued;
542
543                 __kfree_skb(skb);
544                 return 0;
545
546         case DCCP_RESPOND:
547         case DCCP_PARTOPEN:
548                 queued = dccp_rcv_respond_partopen_state_process(sk, skb,
549                                                                  dh, len);
550                 break;
551         }
552
553         if (dh->dccph_type == DCCP_PKT_ACK ||
554             dh->dccph_type == DCCP_PKT_DATAACK) {
555                 switch (old_state) {
556                 case DCCP_PARTOPEN:
557                         sk->sk_state_change(sk);
558                         sk_wake_async(sk, 0, POLL_OUT);
559                         break;
560                 }
561         }
562
563         if (!queued) { 
564 discard:
565                 __kfree_skb(skb);
566         }
567         return 0;
568 }