Root/
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/dccp.h> |
14 | #include <linux/skbuff.h> |
15 | #include <linux/slab.h> |
16 | |
17 | #include <net/sock.h> |
18 | |
19 | #include "ackvec.h" |
20 | #include "ccid.h" |
21 | #include "dccp.h" |
22 | |
23 | /* rate-limit for syncs in reply to sequence-invalid packets; RFC 4340, 7.5.4 */ |
24 | int sysctl_dccp_sync_ratelimit __read_mostly = HZ / 8; |
25 | |
26 | static void dccp_enqueue_skb(struct sock *sk, struct sk_buff *skb) |
27 | { |
28 | __skb_pull(skb, dccp_hdr(skb)->dccph_doff * 4); |
29 | __skb_queue_tail(&sk->sk_receive_queue, skb); |
30 | skb_set_owner_r(skb, sk); |
31 | sk->sk_data_ready(sk, 0); |
32 | } |
33 | |
34 | static void dccp_fin(struct sock *sk, struct sk_buff *skb) |
35 | { |
36 | /* |
37 | * On receiving Close/CloseReq, both RD/WR shutdown are performed. |
38 | * RFC 4340, 8.3 says that we MAY send further Data/DataAcks after |
39 | * receiving the closing segment, but there is no guarantee that such |
40 | * data will be processed at all. |
41 | */ |
42 | sk->sk_shutdown = SHUTDOWN_MASK; |
43 | sock_set_flag(sk, SOCK_DONE); |
44 | dccp_enqueue_skb(sk, skb); |
45 | } |
46 | |
47 | static int dccp_rcv_close(struct sock *sk, struct sk_buff *skb) |
48 | { |
49 | int queued = 0; |
50 | |
51 | switch (sk->sk_state) { |
52 | /* |
53 | * We ignore Close when received in one of the following states: |
54 | * - CLOSED (may be a late or duplicate packet) |
55 | * - PASSIVE_CLOSEREQ (the peer has sent a CloseReq earlier) |
56 | * - RESPOND (already handled by dccp_check_req) |
57 | */ |
58 | case DCCP_CLOSING: |
59 | /* |
60 | * Simultaneous-close: receiving a Close after sending one. This |
61 | * can happen if both client and server perform active-close and |
62 | * will result in an endless ping-pong of crossing and retrans- |
63 | * mitted Close packets, which only terminates when one of the |
64 | * nodes times out (min. 64 seconds). Quicker convergence can be |
65 | * achieved when one of the nodes acts as tie-breaker. |
66 | * This is ok as both ends are done with data transfer and each |
67 | * end is just waiting for the other to acknowledge termination. |
68 | */ |
69 | if (dccp_sk(sk)->dccps_role != DCCP_ROLE_CLIENT) |
70 | break; |
71 | /* fall through */ |
72 | case DCCP_REQUESTING: |
73 | case DCCP_ACTIVE_CLOSEREQ: |
74 | dccp_send_reset(sk, DCCP_RESET_CODE_CLOSED); |
75 | dccp_done(sk); |
76 | break; |
77 | case DCCP_OPEN: |
78 | case DCCP_PARTOPEN: |
79 | /* Give waiting application a chance to read pending data */ |
80 | queued = 1; |
81 | dccp_fin(sk, skb); |
82 | dccp_set_state(sk, DCCP_PASSIVE_CLOSE); |
83 | /* fall through */ |
84 | case DCCP_PASSIVE_CLOSE: |
85 | /* |
86 | * Retransmitted Close: we have already enqueued the first one. |
87 | */ |
88 | sk_wake_async(sk, SOCK_WAKE_WAITD, POLL_HUP); |
89 | } |
90 | return queued; |
91 | } |
92 | |
93 | static int dccp_rcv_closereq(struct sock *sk, struct sk_buff *skb) |
94 | { |
95 | int queued = 0; |
96 | |
97 | /* |
98 | * Step 7: Check for unexpected packet types |
99 | * If (S.is_server and P.type == CloseReq) |
100 | * Send Sync packet acknowledging P.seqno |
101 | * Drop packet and return |
102 | */ |
103 | if (dccp_sk(sk)->dccps_role != DCCP_ROLE_CLIENT) { |
104 | dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq, DCCP_PKT_SYNC); |
105 | return queued; |
106 | } |
107 | |
108 | /* Step 13: process relevant Client states < CLOSEREQ */ |
109 | switch (sk->sk_state) { |
110 | case DCCP_REQUESTING: |
111 | dccp_send_close(sk, 0); |
112 | dccp_set_state(sk, DCCP_CLOSING); |
113 | break; |
114 | case DCCP_OPEN: |
115 | case DCCP_PARTOPEN: |
116 | /* Give waiting application a chance to read pending data */ |
117 | queued = 1; |
118 | dccp_fin(sk, skb); |
119 | dccp_set_state(sk, DCCP_PASSIVE_CLOSEREQ); |
120 | /* fall through */ |
121 | case DCCP_PASSIVE_CLOSEREQ: |
122 | sk_wake_async(sk, SOCK_WAKE_WAITD, POLL_HUP); |
123 | } |
124 | return queued; |
125 | } |
126 | |
127 | static u16 dccp_reset_code_convert(const u8 code) |
128 | { |
129 | const u16 error_code[] = { |
130 | [DCCP_RESET_CODE_CLOSED] = 0, /* normal termination */ |
131 | [DCCP_RESET_CODE_UNSPECIFIED] = 0, /* nothing known */ |
132 | [DCCP_RESET_CODE_ABORTED] = ECONNRESET, |
133 | |
134 | [DCCP_RESET_CODE_NO_CONNECTION] = ECONNREFUSED, |
135 | [DCCP_RESET_CODE_CONNECTION_REFUSED] = ECONNREFUSED, |
136 | [DCCP_RESET_CODE_TOO_BUSY] = EUSERS, |
137 | [DCCP_RESET_CODE_AGGRESSION_PENALTY] = EDQUOT, |
138 | |
139 | [DCCP_RESET_CODE_PACKET_ERROR] = ENOMSG, |
140 | [DCCP_RESET_CODE_BAD_INIT_COOKIE] = EBADR, |
141 | [DCCP_RESET_CODE_BAD_SERVICE_CODE] = EBADRQC, |
142 | [DCCP_RESET_CODE_OPTION_ERROR] = EILSEQ, |
143 | [DCCP_RESET_CODE_MANDATORY_ERROR] = EOPNOTSUPP, |
144 | }; |
145 | |
146 | return code >= DCCP_MAX_RESET_CODES ? 0 : error_code[code]; |
147 | } |
148 | |
149 | static void dccp_rcv_reset(struct sock *sk, struct sk_buff *skb) |
150 | { |
151 | u16 err = dccp_reset_code_convert(dccp_hdr_reset(skb)->dccph_reset_code); |
152 | |
153 | sk->sk_err = err; |
154 | |
155 | /* Queue the equivalent of TCP fin so that dccp_recvmsg exits the loop */ |
156 | dccp_fin(sk, skb); |
157 | |
158 | if (err && !sock_flag(sk, SOCK_DEAD)) |
159 | sk_wake_async(sk, SOCK_WAKE_IO, POLL_ERR); |
160 | dccp_time_wait(sk, DCCP_TIME_WAIT, 0); |
161 | } |
162 | |
163 | static void dccp_event_ack_recv(struct sock *sk, struct sk_buff *skb) |
164 | { |
165 | struct dccp_sock *dp = dccp_sk(sk); |
166 | |
167 | if (dp->dccps_hc_rx_ackvec != NULL) |
168 | dccp_ackvec_check_rcv_ackno(dp->dccps_hc_rx_ackvec, sk, |
169 | DCCP_SKB_CB(skb)->dccpd_ack_seq); |
170 | } |
171 | |
172 | static void dccp_deliver_input_to_ccids(struct sock *sk, struct sk_buff *skb) |
173 | { |
174 | const struct dccp_sock *dp = dccp_sk(sk); |
175 | |
176 | /* Don't deliver to RX CCID when node has shut down read end. */ |
177 | if (!(sk->sk_shutdown & RCV_SHUTDOWN)) |
178 | ccid_hc_rx_packet_recv(dp->dccps_hc_rx_ccid, sk, skb); |
179 | /* |
180 | * Until the TX queue has been drained, we can not honour SHUT_WR, since |
181 | * we need received feedback as input to adjust congestion control. |
182 | */ |
183 | if (sk->sk_write_queue.qlen > 0 || !(sk->sk_shutdown & SEND_SHUTDOWN)) |
184 | ccid_hc_tx_packet_recv(dp->dccps_hc_tx_ccid, sk, skb); |
185 | } |
186 | |
187 | static int dccp_check_seqno(struct sock *sk, struct sk_buff *skb) |
188 | { |
189 | const struct dccp_hdr *dh = dccp_hdr(skb); |
190 | struct dccp_sock *dp = dccp_sk(sk); |
191 | u64 lswl, lawl, seqno = DCCP_SKB_CB(skb)->dccpd_seq, |
192 | ackno = DCCP_SKB_CB(skb)->dccpd_ack_seq; |
193 | |
194 | /* |
195 | * Step 5: Prepare sequence numbers for Sync |
196 | * If P.type == Sync or P.type == SyncAck, |
197 | * If S.AWL <= P.ackno <= S.AWH and P.seqno >= S.SWL, |
198 | * / * P is valid, so update sequence number variables |
199 | * accordingly. After this update, P will pass the tests |
200 | * in Step 6. A SyncAck is generated if necessary in |
201 | * Step 15 * / |
202 | * Update S.GSR, S.SWL, S.SWH |
203 | * Otherwise, |
204 | * Drop packet and return |
205 | */ |
206 | if (dh->dccph_type == DCCP_PKT_SYNC || |
207 | dh->dccph_type == DCCP_PKT_SYNCACK) { |
208 | if (between48(ackno, dp->dccps_awl, dp->dccps_awh) && |
209 | dccp_delta_seqno(dp->dccps_swl, seqno) >= 0) |
210 | dccp_update_gsr(sk, seqno); |
211 | else |
212 | return -1; |
213 | } |
214 | |
215 | /* |
216 | * Step 6: Check sequence numbers |
217 | * Let LSWL = S.SWL and LAWL = S.AWL |
218 | * If P.type == CloseReq or P.type == Close or P.type == Reset, |
219 | * LSWL := S.GSR + 1, LAWL := S.GAR |
220 | * If LSWL <= P.seqno <= S.SWH |
221 | * and (P.ackno does not exist or LAWL <= P.ackno <= S.AWH), |
222 | * Update S.GSR, S.SWL, S.SWH |
223 | * If P.type != Sync, |
224 | * Update S.GAR |
225 | */ |
226 | lswl = dp->dccps_swl; |
227 | lawl = dp->dccps_awl; |
228 | |
229 | if (dh->dccph_type == DCCP_PKT_CLOSEREQ || |
230 | dh->dccph_type == DCCP_PKT_CLOSE || |
231 | dh->dccph_type == DCCP_PKT_RESET) { |
232 | lswl = ADD48(dp->dccps_gsr, 1); |
233 | lawl = dp->dccps_gar; |
234 | } |
235 | |
236 | if (between48(seqno, lswl, dp->dccps_swh) && |
237 | (ackno == DCCP_PKT_WITHOUT_ACK_SEQ || |
238 | between48(ackno, lawl, dp->dccps_awh))) { |
239 | dccp_update_gsr(sk, seqno); |
240 | |
241 | if (dh->dccph_type != DCCP_PKT_SYNC && |
242 | (ackno != DCCP_PKT_WITHOUT_ACK_SEQ)) |
243 | dp->dccps_gar = ackno; |
244 | } else { |
245 | unsigned long now = jiffies; |
246 | /* |
247 | * Step 6: Check sequence numbers |
248 | * Otherwise, |
249 | * If P.type == Reset, |
250 | * Send Sync packet acknowledging S.GSR |
251 | * Otherwise, |
252 | * Send Sync packet acknowledging P.seqno |
253 | * Drop packet and return |
254 | * |
255 | * These Syncs are rate-limited as per RFC 4340, 7.5.4: |
256 | * at most 1 / (dccp_sync_rate_limit * HZ) Syncs per second. |
257 | */ |
258 | if (time_before(now, (dp->dccps_rate_last + |
259 | sysctl_dccp_sync_ratelimit))) |
260 | return 0; |
261 | |
262 | DCCP_WARN("DCCP: Step 6 failed for %s packet, " |
263 | "(LSWL(%llu) <= P.seqno(%llu) <= S.SWH(%llu)) and " |
264 | "(P.ackno %s or LAWL(%llu) <= P.ackno(%llu) <= S.AWH(%llu), " |
265 | "sending SYNC...\n", dccp_packet_name(dh->dccph_type), |
266 | (unsigned long long) lswl, (unsigned long long) seqno, |
267 | (unsigned long long) dp->dccps_swh, |
268 | (ackno == DCCP_PKT_WITHOUT_ACK_SEQ) ? "doesn't exist" |
269 | : "exists", |
270 | (unsigned long long) lawl, (unsigned long long) ackno, |
271 | (unsigned long long) dp->dccps_awh); |
272 | |
273 | dp->dccps_rate_last = now; |
274 | |
275 | if (dh->dccph_type == DCCP_PKT_RESET) |
276 | seqno = dp->dccps_gsr; |
277 | dccp_send_sync(sk, seqno, DCCP_PKT_SYNC); |
278 | return -1; |
279 | } |
280 | |
281 | return 0; |
282 | } |
283 | |
284 | static int __dccp_rcv_established(struct sock *sk, struct sk_buff *skb, |
285 | const struct dccp_hdr *dh, const unsigned len) |
286 | { |
287 | struct dccp_sock *dp = dccp_sk(sk); |
288 | |
289 | switch (dccp_hdr(skb)->dccph_type) { |
290 | case DCCP_PKT_DATAACK: |
291 | case DCCP_PKT_DATA: |
292 | /* |
293 | * FIXME: schedule DATA_DROPPED (RFC 4340, 11.7.2) if and when |
294 | * - sk_shutdown == RCV_SHUTDOWN, use Code 1, "Not Listening" |
295 | * - sk_receive_queue is full, use Code 2, "Receive Buffer" |
296 | */ |
297 | dccp_enqueue_skb(sk, skb); |
298 | return 0; |
299 | case DCCP_PKT_ACK: |
300 | goto discard; |
301 | case DCCP_PKT_RESET: |
302 | /* |
303 | * Step 9: Process Reset |
304 | * If P.type == Reset, |
305 | * Tear down connection |
306 | * S.state := TIMEWAIT |
307 | * Set TIMEWAIT timer |
308 | * Drop packet and return |
309 | */ |
310 | dccp_rcv_reset(sk, skb); |
311 | return 0; |
312 | case DCCP_PKT_CLOSEREQ: |
313 | if (dccp_rcv_closereq(sk, skb)) |
314 | return 0; |
315 | goto discard; |
316 | case DCCP_PKT_CLOSE: |
317 | if (dccp_rcv_close(sk, skb)) |
318 | return 0; |
319 | goto discard; |
320 | case DCCP_PKT_REQUEST: |
321 | /* Step 7 |
322 | * or (S.is_server and P.type == Response) |
323 | * or (S.is_client and P.type == Request) |
324 | * or (S.state >= OPEN and P.type == Request |
325 | * and P.seqno >= S.OSR) |
326 | * or (S.state >= OPEN and P.type == Response |
327 | * and P.seqno >= S.OSR) |
328 | * or (S.state == RESPOND and P.type == Data), |
329 | * Send Sync packet acknowledging P.seqno |
330 | * Drop packet and return |
331 | */ |
332 | if (dp->dccps_role != DCCP_ROLE_LISTEN) |
333 | goto send_sync; |
334 | goto check_seq; |
335 | case DCCP_PKT_RESPONSE: |
336 | if (dp->dccps_role != DCCP_ROLE_CLIENT) |
337 | goto send_sync; |
338 | check_seq: |
339 | if (dccp_delta_seqno(dp->dccps_osr, |
340 | DCCP_SKB_CB(skb)->dccpd_seq) >= 0) { |
341 | send_sync: |
342 | dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq, |
343 | DCCP_PKT_SYNC); |
344 | } |
345 | break; |
346 | case DCCP_PKT_SYNC: |
347 | dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq, |
348 | DCCP_PKT_SYNCACK); |
349 | /* |
350 | * From RFC 4340, sec. 5.7 |
351 | * |
352 | * As with DCCP-Ack packets, DCCP-Sync and DCCP-SyncAck packets |
353 | * MAY have non-zero-length application data areas, whose |
354 | * contents receivers MUST ignore. |
355 | */ |
356 | goto discard; |
357 | } |
358 | |
359 | DCCP_INC_STATS_BH(DCCP_MIB_INERRS); |
360 | discard: |
361 | __kfree_skb(skb); |
362 | return 0; |
363 | } |
364 | |
365 | int dccp_rcv_established(struct sock *sk, struct sk_buff *skb, |
366 | const struct dccp_hdr *dh, const unsigned len) |
367 | { |
368 | struct dccp_sock *dp = dccp_sk(sk); |
369 | |
370 | if (dccp_check_seqno(sk, skb)) |
371 | goto discard; |
372 | |
373 | if (dccp_parse_options(sk, NULL, skb)) |
374 | return 1; |
375 | |
376 | if (DCCP_SKB_CB(skb)->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ) |
377 | dccp_event_ack_recv(sk, skb); |
378 | |
379 | if (dp->dccps_hc_rx_ackvec != NULL && |
380 | dccp_ackvec_add(dp->dccps_hc_rx_ackvec, sk, |
381 | DCCP_SKB_CB(skb)->dccpd_seq, |
382 | DCCP_ACKVEC_STATE_RECEIVED)) |
383 | goto discard; |
384 | dccp_deliver_input_to_ccids(sk, skb); |
385 | |
386 | return __dccp_rcv_established(sk, skb, dh, len); |
387 | discard: |
388 | __kfree_skb(skb); |
389 | return 0; |
390 | } |
391 | |
392 | EXPORT_SYMBOL_GPL(dccp_rcv_established); |
393 | |
394 | static int dccp_rcv_request_sent_state_process(struct sock *sk, |
395 | struct sk_buff *skb, |
396 | const struct dccp_hdr *dh, |
397 | const unsigned len) |
398 | { |
399 | /* |
400 | * Step 4: Prepare sequence numbers in REQUEST |
401 | * If S.state == REQUEST, |
402 | * If (P.type == Response or P.type == Reset) |
403 | * and S.AWL <= P.ackno <= S.AWH, |
404 | * / * Set sequence number variables corresponding to the |
405 | * other endpoint, so P will pass the tests in Step 6 * / |
406 | * Set S.GSR, S.ISR, S.SWL, S.SWH |
407 | * / * Response processing continues in Step 10; Reset |
408 | * processing continues in Step 9 * / |
409 | */ |
410 | if (dh->dccph_type == DCCP_PKT_RESPONSE) { |
411 | const struct inet_connection_sock *icsk = inet_csk(sk); |
412 | struct dccp_sock *dp = dccp_sk(sk); |
413 | long tstamp = dccp_timestamp(); |
414 | |
415 | if (!between48(DCCP_SKB_CB(skb)->dccpd_ack_seq, |
416 | dp->dccps_awl, dp->dccps_awh)) { |
417 | dccp_pr_debug("invalid ackno: S.AWL=%llu, " |
418 | "P.ackno=%llu, S.AWH=%llu\n", |
419 | (unsigned long long)dp->dccps_awl, |
420 | (unsigned long long)DCCP_SKB_CB(skb)->dccpd_ack_seq, |
421 | (unsigned long long)dp->dccps_awh); |
422 | goto out_invalid_packet; |
423 | } |
424 | |
425 | /* |
426 | * If option processing (Step 8) failed, return 1 here so that |
427 | * dccp_v4_do_rcv() sends a Reset. The Reset code depends on |
428 | * the option type and is set in dccp_parse_options(). |
429 | */ |
430 | if (dccp_parse_options(sk, NULL, skb)) |
431 | return 1; |
432 | |
433 | /* Obtain usec RTT sample from SYN exchange (used by TFRC). */ |
434 | if (likely(dp->dccps_options_received.dccpor_timestamp_echo)) |
435 | dp->dccps_syn_rtt = dccp_sample_rtt(sk, 10 * (tstamp - |
436 | dp->dccps_options_received.dccpor_timestamp_echo)); |
437 | |
438 | /* Stop the REQUEST timer */ |
439 | inet_csk_clear_xmit_timer(sk, ICSK_TIME_RETRANS); |
440 | WARN_ON(sk->sk_send_head == NULL); |
441 | kfree_skb(sk->sk_send_head); |
442 | sk->sk_send_head = NULL; |
443 | |
444 | dp->dccps_isr = DCCP_SKB_CB(skb)->dccpd_seq; |
445 | dccp_update_gsr(sk, dp->dccps_isr); |
446 | /* |
447 | * SWL and AWL are initially adjusted so that they are not less than |
448 | * the initial Sequence Numbers received and sent, respectively: |
449 | * SWL := max(GSR + 1 - floor(W/4), ISR), |
450 | * AWL := max(GSS - W' + 1, ISS). |
451 | * These adjustments MUST be applied only at the beginning of the |
452 | * connection. |
453 | * |
454 | * AWL was adjusted in dccp_v4_connect -acme |
455 | */ |
456 | dccp_set_seqno(&dp->dccps_swl, |
457 | max48(dp->dccps_swl, dp->dccps_isr)); |
458 | |
459 | dccp_sync_mss(sk, icsk->icsk_pmtu_cookie); |
460 | |
461 | /* |
462 | * Step 10: Process REQUEST state (second part) |
463 | * If S.state == REQUEST, |
464 | * / * If we get here, P is a valid Response from the |
465 | * server (see Step 4), and we should move to |
466 | * PARTOPEN state. PARTOPEN means send an Ack, |
467 | * don't send Data packets, retransmit Acks |
468 | * periodically, and always include any Init Cookie |
469 | * from the Response * / |
470 | * S.state := PARTOPEN |
471 | * Set PARTOPEN timer |
472 | * Continue with S.state == PARTOPEN |
473 | * / * Step 12 will send the Ack completing the |
474 | * three-way handshake * / |
475 | */ |
476 | dccp_set_state(sk, DCCP_PARTOPEN); |
477 | |
478 | /* |
479 | * If feature negotiation was successful, activate features now; |
480 | * an activation failure means that this host could not activate |
481 | * one ore more features (e.g. insufficient memory), which would |
482 | * leave at least one feature in an undefined state. |
483 | */ |
484 | if (dccp_feat_activate_values(sk, &dp->dccps_featneg)) |
485 | goto unable_to_proceed; |
486 | |
487 | /* Make sure socket is routed, for correct metrics. */ |
488 | icsk->icsk_af_ops->rebuild_header(sk); |
489 | |
490 | if (!sock_flag(sk, SOCK_DEAD)) { |
491 | sk->sk_state_change(sk); |
492 | sk_wake_async(sk, SOCK_WAKE_IO, POLL_OUT); |
493 | } |
494 | |
495 | if (sk->sk_write_pending || icsk->icsk_ack.pingpong || |
496 | icsk->icsk_accept_queue.rskq_defer_accept) { |
497 | /* Save one ACK. Data will be ready after |
498 | * several ticks, if write_pending is set. |
499 | * |
500 | * It may be deleted, but with this feature tcpdumps |
501 | * look so _wonderfully_ clever, that I was not able |
502 | * to stand against the temptation 8) --ANK |
503 | */ |
504 | /* |
505 | * OK, in DCCP we can as well do a similar trick, its |
506 | * even in the draft, but there is no need for us to |
507 | * schedule an ack here, as dccp_sendmsg does this for |
508 | * us, also stated in the draft. -acme |
509 | */ |
510 | __kfree_skb(skb); |
511 | return 0; |
512 | } |
513 | dccp_send_ack(sk); |
514 | return -1; |
515 | } |
516 | |
517 | out_invalid_packet: |
518 | /* dccp_v4_do_rcv will send a reset */ |
519 | DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_PACKET_ERROR; |
520 | return 1; |
521 | |
522 | unable_to_proceed: |
523 | DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_ABORTED; |
524 | /* |
525 | * We mark this socket as no longer usable, so that the loop in |
526 | * dccp_sendmsg() terminates and the application gets notified. |
527 | */ |
528 | dccp_set_state(sk, DCCP_CLOSED); |
529 | sk->sk_err = ECOMM; |
530 | return 1; |
531 | } |
532 | |
533 | static int dccp_rcv_respond_partopen_state_process(struct sock *sk, |
534 | struct sk_buff *skb, |
535 | const struct dccp_hdr *dh, |
536 | const unsigned len) |
537 | { |
538 | struct dccp_sock *dp = dccp_sk(sk); |
539 | u32 sample = dp->dccps_options_received.dccpor_timestamp_echo; |
540 | int queued = 0; |
541 | |
542 | switch (dh->dccph_type) { |
543 | case DCCP_PKT_RESET: |
544 | inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK); |
545 | break; |
546 | case DCCP_PKT_DATA: |
547 | if (sk->sk_state == DCCP_RESPOND) |
548 | break; |
549 | case DCCP_PKT_DATAACK: |
550 | case DCCP_PKT_ACK: |
551 | /* |
552 | * FIXME: we should be reseting the PARTOPEN (DELACK) timer |
553 | * here but only if we haven't used the DELACK timer for |
554 | * something else, like sending a delayed ack for a TIMESTAMP |
555 | * echo, etc, for now were not clearing it, sending an extra |
556 | * ACK when there is nothing else to do in DELACK is not a big |
557 | * deal after all. |
558 | */ |
559 | |
560 | /* Stop the PARTOPEN timer */ |
561 | if (sk->sk_state == DCCP_PARTOPEN) |
562 | inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK); |
563 | |
564 | /* Obtain usec RTT sample from SYN exchange (used by TFRC). */ |
565 | if (likely(sample)) { |
566 | long delta = dccp_timestamp() - sample; |
567 | |
568 | dp->dccps_syn_rtt = dccp_sample_rtt(sk, 10 * delta); |
569 | } |
570 | |
571 | dp->dccps_osr = DCCP_SKB_CB(skb)->dccpd_seq; |
572 | dccp_set_state(sk, DCCP_OPEN); |
573 | |
574 | if (dh->dccph_type == DCCP_PKT_DATAACK || |
575 | dh->dccph_type == DCCP_PKT_DATA) { |
576 | __dccp_rcv_established(sk, skb, dh, len); |
577 | queued = 1; /* packet was queued |
578 | (by __dccp_rcv_established) */ |
579 | } |
580 | break; |
581 | } |
582 | |
583 | return queued; |
584 | } |
585 | |
586 | int dccp_rcv_state_process(struct sock *sk, struct sk_buff *skb, |
587 | struct dccp_hdr *dh, unsigned len) |
588 | { |
589 | struct dccp_sock *dp = dccp_sk(sk); |
590 | struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb); |
591 | const int old_state = sk->sk_state; |
592 | int queued = 0; |
593 | |
594 | /* |
595 | * Step 3: Process LISTEN state |
596 | * |
597 | * If S.state == LISTEN, |
598 | * If P.type == Request or P contains a valid Init Cookie option, |
599 | * (* Must scan the packet's options to check for Init |
600 | * Cookies. Only Init Cookies are processed here, |
601 | * however; other options are processed in Step 8. This |
602 | * scan need only be performed if the endpoint uses Init |
603 | * Cookies *) |
604 | * (* Generate a new socket and switch to that socket *) |
605 | * Set S := new socket for this port pair |
606 | * S.state = RESPOND |
607 | * Choose S.ISS (initial seqno) or set from Init Cookies |
608 | * Initialize S.GAR := S.ISS |
609 | * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init |
610 | * Cookies Continue with S.state == RESPOND |
611 | * (* A Response packet will be generated in Step 11 *) |
612 | * Otherwise, |
613 | * Generate Reset(No Connection) unless P.type == Reset |
614 | * Drop packet and return |
615 | */ |
616 | if (sk->sk_state == DCCP_LISTEN) { |
617 | if (dh->dccph_type == DCCP_PKT_REQUEST) { |
618 | if (inet_csk(sk)->icsk_af_ops->conn_request(sk, |
619 | skb) < 0) |
620 | return 1; |
621 | goto discard; |
622 | } |
623 | if (dh->dccph_type == DCCP_PKT_RESET) |
624 | goto discard; |
625 | |
626 | /* Caller (dccp_v4_do_rcv) will send Reset */ |
627 | dcb->dccpd_reset_code = DCCP_RESET_CODE_NO_CONNECTION; |
628 | return 1; |
629 | } |
630 | |
631 | if (sk->sk_state != DCCP_REQUESTING && sk->sk_state != DCCP_RESPOND) { |
632 | if (dccp_check_seqno(sk, skb)) |
633 | goto discard; |
634 | |
635 | /* |
636 | * Step 8: Process options and mark acknowledgeable |
637 | */ |
638 | if (dccp_parse_options(sk, NULL, skb)) |
639 | return 1; |
640 | |
641 | if (dcb->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ) |
642 | dccp_event_ack_recv(sk, skb); |
643 | |
644 | if (dp->dccps_hc_rx_ackvec != NULL && |
645 | dccp_ackvec_add(dp->dccps_hc_rx_ackvec, sk, |
646 | DCCP_SKB_CB(skb)->dccpd_seq, |
647 | DCCP_ACKVEC_STATE_RECEIVED)) |
648 | goto discard; |
649 | |
650 | dccp_deliver_input_to_ccids(sk, skb); |
651 | } |
652 | |
653 | /* |
654 | * Step 9: Process Reset |
655 | * If P.type == Reset, |
656 | * Tear down connection |
657 | * S.state := TIMEWAIT |
658 | * Set TIMEWAIT timer |
659 | * Drop packet and return |
660 | */ |
661 | if (dh->dccph_type == DCCP_PKT_RESET) { |
662 | dccp_rcv_reset(sk, skb); |
663 | return 0; |
664 | /* |
665 | * Step 7: Check for unexpected packet types |
666 | * If (S.is_server and P.type == Response) |
667 | * or (S.is_client and P.type == Request) |
668 | * or (S.state == RESPOND and P.type == Data), |
669 | * Send Sync packet acknowledging P.seqno |
670 | * Drop packet and return |
671 | */ |
672 | } else if ((dp->dccps_role != DCCP_ROLE_CLIENT && |
673 | dh->dccph_type == DCCP_PKT_RESPONSE) || |
674 | (dp->dccps_role == DCCP_ROLE_CLIENT && |
675 | dh->dccph_type == DCCP_PKT_REQUEST) || |
676 | (sk->sk_state == DCCP_RESPOND && |
677 | dh->dccph_type == DCCP_PKT_DATA)) { |
678 | dccp_send_sync(sk, dcb->dccpd_seq, DCCP_PKT_SYNC); |
679 | goto discard; |
680 | } else if (dh->dccph_type == DCCP_PKT_CLOSEREQ) { |
681 | if (dccp_rcv_closereq(sk, skb)) |
682 | return 0; |
683 | goto discard; |
684 | } else if (dh->dccph_type == DCCP_PKT_CLOSE) { |
685 | if (dccp_rcv_close(sk, skb)) |
686 | return 0; |
687 | goto discard; |
688 | } |
689 | |
690 | switch (sk->sk_state) { |
691 | case DCCP_CLOSED: |
692 | dcb->dccpd_reset_code = DCCP_RESET_CODE_NO_CONNECTION; |
693 | return 1; |
694 | |
695 | case DCCP_REQUESTING: |
696 | queued = dccp_rcv_request_sent_state_process(sk, skb, dh, len); |
697 | if (queued >= 0) |
698 | return queued; |
699 | |
700 | __kfree_skb(skb); |
701 | return 0; |
702 | |
703 | case DCCP_RESPOND: |
704 | case DCCP_PARTOPEN: |
705 | queued = dccp_rcv_respond_partopen_state_process(sk, skb, |
706 | dh, len); |
707 | break; |
708 | } |
709 | |
710 | if (dh->dccph_type == DCCP_PKT_ACK || |
711 | dh->dccph_type == DCCP_PKT_DATAACK) { |
712 | switch (old_state) { |
713 | case DCCP_PARTOPEN: |
714 | sk->sk_state_change(sk); |
715 | sk_wake_async(sk, SOCK_WAKE_IO, POLL_OUT); |
716 | break; |
717 | } |
718 | } else if (unlikely(dh->dccph_type == DCCP_PKT_SYNC)) { |
719 | dccp_send_sync(sk, dcb->dccpd_seq, DCCP_PKT_SYNCACK); |
720 | goto discard; |
721 | } |
722 | |
723 | if (!queued) { |
724 | discard: |
725 | __kfree_skb(skb); |
726 | } |
727 | return 0; |
728 | } |
729 | |
730 | EXPORT_SYMBOL_GPL(dccp_rcv_state_process); |
731 | |
732 | /** |
733 | * dccp_sample_rtt - Validate and finalise computation of RTT sample |
734 | * @delta: number of microseconds between packet and acknowledgment |
735 | * The routine is kept generic to work in different contexts. It should be |
736 | * called immediately when the ACK used for the RTT sample arrives. |
737 | */ |
738 | u32 dccp_sample_rtt(struct sock *sk, long delta) |
739 | { |
740 | /* dccpor_elapsed_time is either zeroed out or set and > 0 */ |
741 | delta -= dccp_sk(sk)->dccps_options_received.dccpor_elapsed_time * 10; |
742 | |
743 | if (unlikely(delta <= 0)) { |
744 | DCCP_WARN("unusable RTT sample %ld, using min\n", delta); |
745 | return DCCP_SANE_RTT_MIN; |
746 | } |
747 | if (unlikely(delta > DCCP_SANE_RTT_MAX)) { |
748 | DCCP_WARN("RTT sample %ld too large, using max\n", delta); |
749 | return DCCP_SANE_RTT_MAX; |
750 | } |
751 | |
752 | return delta; |
753 | } |
754 |
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