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Arnaldo Carvalho de Meloae31c332005-09-18 00:17:51 -07001/*
2 * net/dccp/ackvec.c
3 *
4 * An implementation of the DCCP protocol
5 * Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
6 *
7 * This program is free software; you can redistribute it and/or modify it
8 * under the terms of the GNU General Public License as published by the
9 * Free Software Foundation; version 2 of the License;
10 */
11
12#include "ackvec.h"
13#include "dccp.h"
14
15#include <linux/dccp.h>
16#include <linux/skbuff.h>
17
18#include <net/sock.h>
19
20int dccp_insert_option_ackvec(struct sock *sk, struct sk_buff *skb)
21{
22 struct dccp_sock *dp = dccp_sk(sk);
23 struct dccp_ackvec *av = dp->dccps_hc_rx_ackvec;
24 int len = av->dccpav_vec_len + 2;
25 struct timeval now;
26 u32 elapsed_time;
27 unsigned char *to, *from;
28
29 dccp_timestamp(sk, &now);
30 elapsed_time = timeval_delta(&now, &av->dccpav_time) / 10;
31
32 if (elapsed_time != 0)
33 dccp_insert_option_elapsed_time(sk, skb, elapsed_time);
34
35 if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)
36 return -1;
37
38 /*
39 * XXX: now we have just one ack vector sent record, so
40 * we have to wait for it to be cleared.
41 *
42 * Of course this is not acceptable, but this is just for
43 * basic testing now.
44 */
45 if (av->dccpav_ack_seqno != DCCP_MAX_SEQNO + 1)
46 return -1;
47
48 DCCP_SKB_CB(skb)->dccpd_opt_len += len;
49
50 to = skb_push(skb, len);
51 *to++ = DCCPO_ACK_VECTOR_0;
52 *to++ = len;
53
54 len = av->dccpav_vec_len;
55 from = av->dccpav_buf + av->dccpav_buf_head;
56
57 /* Check if buf_head wraps */
58 if (av->dccpav_buf_head + len > av->dccpav_vec_len) {
59 const u32 tailsize = (av->dccpav_vec_len - av->dccpav_buf_head);
60
61 memcpy(to, from, tailsize);
62 to += tailsize;
63 len -= tailsize;
64 from = av->dccpav_buf;
65 }
66
67 memcpy(to, from, len);
68 /*
69 * From draft-ietf-dccp-spec-11.txt:
70 *
71 * For each acknowledgement it sends, the HC-Receiver will add an
72 * acknowledgement record. ack_seqno will equal the HC-Receiver
73 * sequence number it used for the ack packet; ack_ptr will equal
74 * buf_head; ack_ackno will equal buf_ackno; and ack_nonce will
75 * equal buf_nonce.
76 *
77 * This implemention uses just one ack record for now.
78 */
79 av->dccpav_ack_seqno = DCCP_SKB_CB(skb)->dccpd_seq;
80 av->dccpav_ack_ptr = av->dccpav_buf_head;
81 av->dccpav_ack_ackno = av->dccpav_buf_ackno;
82 av->dccpav_ack_nonce = av->dccpav_buf_nonce;
83 av->dccpav_sent_len = av->dccpav_vec_len;
84
85 dccp_pr_debug("%sACK Vector 0, len=%d, ack_seqno=%llu, "
86 "ack_ackno=%llu\n",
87 debug_prefix, av->dccpav_sent_len,
88 (unsigned long long)av->dccpav_ack_seqno,
89 (unsigned long long)av->dccpav_ack_ackno);
90 return -1;
91}
92
93struct dccp_ackvec *dccp_ackvec_alloc(const unsigned int len,
Al Virodd0fc662005-10-07 07:46:04 +010094 const gfp_t priority)
Arnaldo Carvalho de Meloae31c332005-09-18 00:17:51 -070095{
96 struct dccp_ackvec *av = kmalloc(sizeof(*av) + len, priority);
97
98 if (av != NULL) {
99 av->dccpav_buf_len = len;
100 av->dccpav_buf_head =
101 av->dccpav_buf_tail = av->dccpav_buf_len - 1;
102 av->dccpav_buf_ackno =
103 av->dccpav_ack_ackno = av->dccpav_ack_seqno = ~0LLU;
104 av->dccpav_buf_nonce = av->dccpav_buf_nonce = 0;
105 av->dccpav_ack_ptr = 0;
106 av->dccpav_time.tv_sec = 0;
107 av->dccpav_time.tv_usec = 0;
108 av->dccpav_sent_len = av->dccpav_vec_len = 0;
109 }
110
111 return av;
112}
113
114void dccp_ackvec_free(struct dccp_ackvec *av)
115{
116 kfree(av);
117}
118
119static inline u8 dccp_ackvec_state(const struct dccp_ackvec *av,
120 const unsigned int index)
121{
122 return av->dccpav_buf[index] & DCCP_ACKVEC_STATE_MASK;
123}
124
125static inline u8 dccp_ackvec_len(const struct dccp_ackvec *av,
126 const unsigned int index)
127{
128 return av->dccpav_buf[index] & DCCP_ACKVEC_LEN_MASK;
129}
130
131/*
132 * If several packets are missing, the HC-Receiver may prefer to enter multiple
133 * bytes with run length 0, rather than a single byte with a larger run length;
134 * this simplifies table updates if one of the missing packets arrives.
135 */
136static inline int dccp_ackvec_set_buf_head_state(struct dccp_ackvec *av,
137 const unsigned int packets,
138 const unsigned char state)
139{
140 unsigned int gap;
141 signed long new_head;
142
143 if (av->dccpav_vec_len + packets > av->dccpav_buf_len)
144 return -ENOBUFS;
145
146 gap = packets - 1;
147 new_head = av->dccpav_buf_head - packets;
148
149 if (new_head < 0) {
150 if (gap > 0) {
151 memset(av->dccpav_buf, DCCP_ACKVEC_STATE_NOT_RECEIVED,
152 gap + new_head + 1);
153 gap = -new_head;
154 }
155 new_head += av->dccpav_buf_len;
156 }
157
158 av->dccpav_buf_head = new_head;
159
160 if (gap > 0)
161 memset(av->dccpav_buf + av->dccpav_buf_head + 1,
162 DCCP_ACKVEC_STATE_NOT_RECEIVED, gap);
163
164 av->dccpav_buf[av->dccpav_buf_head] = state;
165 av->dccpav_vec_len += packets;
166 return 0;
167}
168
169/*
170 * Implements the draft-ietf-dccp-spec-11.txt Appendix A
171 */
172int dccp_ackvec_add(struct dccp_ackvec *av, const struct sock *sk,
173 const u64 ackno, const u8 state)
174{
175 /*
176 * Check at the right places if the buffer is full, if it is, tell the
177 * caller to start dropping packets till the HC-Sender acks our ACK
178 * vectors, when we will free up space in dccpav_buf.
179 *
180 * We may well decide to do buffer compression, etc, but for now lets
181 * just drop.
182 *
183 * From Appendix A:
184 *
185 * Of course, the circular buffer may overflow, either when the
186 * HC-Sender is sending data at a very high rate, when the
187 * HC-Receiver's acknowledgements are not reaching the HC-Sender,
188 * or when the HC-Sender is forgetting to acknowledge those acks
189 * (so the HC-Receiver is unable to clean up old state). In this
190 * case, the HC-Receiver should either compress the buffer (by
191 * increasing run lengths when possible), transfer its state to
192 * a larger buffer, or, as a last resort, drop all received
193 * packets, without processing them whatsoever, until its buffer
194 * shrinks again.
195 */
196
197 /* See if this is the first ackno being inserted */
198 if (av->dccpav_vec_len == 0) {
199 av->dccpav_buf[av->dccpav_buf_head] = state;
200 av->dccpav_vec_len = 1;
201 } else if (after48(ackno, av->dccpav_buf_ackno)) {
202 const u64 delta = dccp_delta_seqno(av->dccpav_buf_ackno,
203 ackno);
204
205 /*
206 * Look if the state of this packet is the same as the
207 * previous ackno and if so if we can bump the head len.
208 */
209 if (delta == 1 &&
210 dccp_ackvec_state(av, av->dccpav_buf_head) == state &&
211 (dccp_ackvec_len(av, av->dccpav_buf_head) <
212 DCCP_ACKVEC_LEN_MASK))
213 av->dccpav_buf[av->dccpav_buf_head]++;
214 else if (dccp_ackvec_set_buf_head_state(av, delta, state))
215 return -ENOBUFS;
216 } else {
217 /*
218 * A.1.2. Old Packets
219 *
220 * When a packet with Sequence Number S arrives, and
221 * S <= buf_ackno, the HC-Receiver will scan the table
222 * for the byte corresponding to S. (Indexing structures
223 * could reduce the complexity of this scan.)
224 */
225 u64 delta = dccp_delta_seqno(ackno, av->dccpav_buf_ackno);
226 unsigned int index = av->dccpav_buf_head;
227
228 while (1) {
229 const u8 len = dccp_ackvec_len(av, index);
230 const u8 state = dccp_ackvec_state(av, index);
231 /*
232 * valid packets not yet in dccpav_buf have a reserved
233 * entry, with a len equal to 0.
234 */
235 if (state == DCCP_ACKVEC_STATE_NOT_RECEIVED &&
236 len == 0 && delta == 0) { /* Found our
237 reserved seat! */
238 dccp_pr_debug("Found %llu reserved seat!\n",
239 (unsigned long long)ackno);
240 av->dccpav_buf[index] = state;
241 goto out;
242 }
243 /* len == 0 means one packet */
244 if (delta < len + 1)
245 goto out_duplicate;
246
247 delta -= len + 1;
248 if (++index == av->dccpav_buf_len)
249 index = 0;
250 }
251 }
252
253 av->dccpav_buf_ackno = ackno;
254 dccp_timestamp(sk, &av->dccpav_time);
255out:
256 dccp_pr_debug("");
257 return 0;
258
259out_duplicate:
260 /* Duplicate packet */
261 dccp_pr_debug("Received a dup or already considered lost "
262 "packet: %llu\n", (unsigned long long)ackno);
263 return -EILSEQ;
264}
265
266#ifdef CONFIG_IP_DCCP_DEBUG
267void dccp_ackvector_print(const u64 ackno, const unsigned char *vector, int len)
268{
269 if (!dccp_debug)
270 return;
271
272 printk("ACK vector len=%d, ackno=%llu |", len,
273 (unsigned long long)ackno);
274
275 while (len--) {
276 const u8 state = (*vector & DCCP_ACKVEC_STATE_MASK) >> 6;
277 const u8 rl = *vector & DCCP_ACKVEC_LEN_MASK;
278
279 printk("%d,%d|", state, rl);
280 ++vector;
281 }
282
283 printk("\n");
284}
285
286void dccp_ackvec_print(const struct dccp_ackvec *av)
287{
288 dccp_ackvector_print(av->dccpav_buf_ackno,
289 av->dccpav_buf + av->dccpav_buf_head,
290 av->dccpav_vec_len);
291}
292#endif
293
294static void dccp_ackvec_trow_away_ack_record(struct dccp_ackvec *av)
295{
296 /*
297 * As we're keeping track of the ack vector size (dccpav_vec_len) and
298 * the sent ack vector size (dccpav_sent_len) we don't need
299 * dccpav_buf_tail at all, but keep this code here as in the future
300 * we'll implement a vector of ack records, as suggested in
301 * draft-ietf-dccp-spec-11.txt Appendix A. -acme
302 */
303#if 0
304 av->dccpav_buf_tail = av->dccpav_ack_ptr + 1;
305 if (av->dccpav_buf_tail >= av->dccpav_vec_len)
306 av->dccpav_buf_tail -= av->dccpav_vec_len;
307#endif
308 av->dccpav_vec_len -= av->dccpav_sent_len;
309}
310
311void dccp_ackvec_check_rcv_ackno(struct dccp_ackvec *av, struct sock *sk,
312 const u64 ackno)
313{
314 /* Check if we actually sent an ACK vector */
315 if (av->dccpav_ack_seqno == DCCP_MAX_SEQNO + 1)
316 return;
317
318 if (ackno == av->dccpav_ack_seqno) {
319#ifdef CONFIG_IP_DCCP_DEBUG
320 struct dccp_sock *dp = dccp_sk(sk);
321 const char *debug_prefix = dp->dccps_role == DCCP_ROLE_CLIENT ?
322 "CLIENT rx ack: " : "server rx ack: ";
323#endif
324 dccp_pr_debug("%sACK packet 0, len=%d, ack_seqno=%llu, "
325 "ack_ackno=%llu, ACKED!\n",
326 debug_prefix, 1,
327 (unsigned long long)av->dccpav_ack_seqno,
328 (unsigned long long)av->dccpav_ack_ackno);
329 dccp_ackvec_trow_away_ack_record(av);
330 av->dccpav_ack_seqno = DCCP_MAX_SEQNO + 1;
331 }
332}
333
334static void dccp_ackvec_check_rcv_ackvector(struct dccp_ackvec *av,
335 struct sock *sk, u64 ackno,
336 const unsigned char len,
337 const unsigned char *vector)
338{
339 unsigned char i;
340
341 /* Check if we actually sent an ACK vector */
342 if (av->dccpav_ack_seqno == DCCP_MAX_SEQNO + 1)
343 return;
344 /*
345 * We're in the receiver half connection, so if the received an ACK
346 * vector ackno (e.g. 50) before dccpav_ack_seqno (e.g. 52), we're
347 * not interested.
348 *
349 * Extra explanation with example:
350 *
351 * if we received an ACK vector with ackno 50, it can only be acking
352 * 50, 49, 48, etc, not 52 (the seqno for the ACK vector we sent).
353 */
354 /* dccp_pr_debug("is %llu < %llu? ", ackno, av->dccpav_ack_seqno); */
355 if (before48(ackno, av->dccpav_ack_seqno)) {
356 /* dccp_pr_debug_cat("yes\n"); */
357 return;
358 }
359 /* dccp_pr_debug_cat("no\n"); */
360
361 i = len;
362 while (i--) {
363 const u8 rl = *vector & DCCP_ACKVEC_LEN_MASK;
364 u64 ackno_end_rl;
365
366 dccp_set_seqno(&ackno_end_rl, ackno - rl);
367
368 /*
369 * dccp_pr_debug("is %llu <= %llu <= %llu? ", ackno_end_rl,
370 * av->dccpav_ack_seqno, ackno);
371 */
372 if (between48(av->dccpav_ack_seqno, ackno_end_rl, ackno)) {
373 const u8 state = (*vector &
374 DCCP_ACKVEC_STATE_MASK) >> 6;
375 /* dccp_pr_debug_cat("yes\n"); */
376
377 if (state != DCCP_ACKVEC_STATE_NOT_RECEIVED) {
378#ifdef CONFIG_IP_DCCP_DEBUG
379 struct dccp_sock *dp = dccp_sk(sk);
380 const char *debug_prefix =
381 dp->dccps_role == DCCP_ROLE_CLIENT ?
382 "CLIENT rx ack: " : "server rx ack: ";
383#endif
384 dccp_pr_debug("%sACK vector 0, len=%d, "
385 "ack_seqno=%llu, ack_ackno=%llu, "
386 "ACKED!\n",
387 debug_prefix, len,
388 (unsigned long long)
389 av->dccpav_ack_seqno,
390 (unsigned long long)
391 av->dccpav_ack_ackno);
392 dccp_ackvec_trow_away_ack_record(av);
393 }
394 /*
395 * If dccpav_ack_seqno was not received, no problem
396 * we'll send another ACK vector.
397 */
398 av->dccpav_ack_seqno = DCCP_MAX_SEQNO + 1;
399 break;
400 }
401 /* dccp_pr_debug_cat("no\n"); */
402
403 dccp_set_seqno(&ackno, ackno_end_rl - 1);
404 ++vector;
405 }
406}
407
408int dccp_ackvec_parse(struct sock *sk, const struct sk_buff *skb,
409 const u8 opt, const u8 *value, const u8 len)
410{
411 if (len > DCCP_MAX_ACKVEC_LEN)
412 return -1;
413
414 /* dccp_ackvector_print(DCCP_SKB_CB(skb)->dccpd_ack_seq, value, len); */
415 dccp_ackvec_check_rcv_ackvector(dccp_sk(sk)->dccps_hc_rx_ackvec, sk,
416 DCCP_SKB_CB(skb)->dccpd_ack_seq,
417 len, value);
418 return 0;
419}