dccp: remove unused function argument
[linux-2.6.git] / net / dccp / ackvec.c
1 /*
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/init.h>
16 #include <linux/errno.h>
17 #include <linux/kernel.h>
18 #include <linux/skbuff.h>
19 #include <linux/slab.h>
20
21 #include <net/sock.h>
22
23 static struct kmem_cache *dccp_ackvec_slab;
24 static struct kmem_cache *dccp_ackvec_record_slab;
25
26 static struct dccp_ackvec_record *dccp_ackvec_record_new(void)
27 {
28         struct dccp_ackvec_record *avr =
29                         kmem_cache_alloc(dccp_ackvec_record_slab, GFP_ATOMIC);
30
31         if (avr != NULL)
32                 INIT_LIST_HEAD(&avr->avr_node);
33
34         return avr;
35 }
36
37 static void dccp_ackvec_record_delete(struct dccp_ackvec_record *avr)
38 {
39         if (unlikely(avr == NULL))
40                 return;
41         /* Check if deleting a linked record */
42         WARN_ON(!list_empty(&avr->avr_node));
43         kmem_cache_free(dccp_ackvec_record_slab, avr);
44 }
45
46 static void dccp_ackvec_insert_avr(struct dccp_ackvec *av,
47                                    struct dccp_ackvec_record *avr)
48 {
49         /*
50          * AVRs are sorted by seqno. Since we are sending them in order, we
51          * just add the AVR at the head of the list.
52          * -sorbo.
53          */
54         if (!list_empty(&av->av_records)) {
55                 const struct dccp_ackvec_record *head =
56                                         list_entry(av->av_records.next,
57                                                    struct dccp_ackvec_record,
58                                                    avr_node);
59                 BUG_ON(before48(avr->avr_ack_seqno, head->avr_ack_seqno));
60         }
61
62         list_add(&avr->avr_node, &av->av_records);
63 }
64
65 int dccp_insert_option_ackvec(struct sock *sk, struct sk_buff *skb)
66 {
67         struct dccp_sock *dp = dccp_sk(sk);
68         struct dccp_ackvec *av = dp->dccps_hc_rx_ackvec;
69         /* Figure out how many options do we need to represent the ackvec */
70         const u8 nr_opts = DIV_ROUND_UP(av->av_vec_len, DCCP_SINGLE_OPT_MAXLEN);
71         u16 len = av->av_vec_len + 2 * nr_opts, i;
72         u32 elapsed_time;
73         const unsigned char *tail, *from;
74         unsigned char *to;
75         struct dccp_ackvec_record *avr;
76         suseconds_t delta;
77
78         if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)
79                 return -1;
80
81         delta = ktime_us_delta(ktime_get_real(), av->av_time);
82         elapsed_time = delta / 10;
83
84         if (elapsed_time != 0 &&
85             dccp_insert_option_elapsed_time(skb, elapsed_time))
86                 return -1;
87
88         avr = dccp_ackvec_record_new();
89         if (avr == NULL)
90                 return -1;
91
92         DCCP_SKB_CB(skb)->dccpd_opt_len += len;
93
94         to   = skb_push(skb, len);
95         len  = av->av_vec_len;
96         from = av->av_buf + av->av_buf_head;
97         tail = av->av_buf + DCCP_MAX_ACKVEC_LEN;
98
99         for (i = 0; i < nr_opts; ++i) {
100                 int copylen = len;
101
102                 if (len > DCCP_SINGLE_OPT_MAXLEN)
103                         copylen = DCCP_SINGLE_OPT_MAXLEN;
104
105                 *to++ = DCCPO_ACK_VECTOR_0;
106                 *to++ = copylen + 2;
107
108                 /* Check if buf_head wraps */
109                 if (from + copylen > tail) {
110                         const u16 tailsize = tail - from;
111
112                         memcpy(to, from, tailsize);
113                         to      += tailsize;
114                         len     -= tailsize;
115                         copylen -= tailsize;
116                         from    = av->av_buf;
117                 }
118
119                 memcpy(to, from, copylen);
120                 from += copylen;
121                 to   += copylen;
122                 len  -= copylen;
123         }
124
125         /*
126          *      From RFC 4340, A.2:
127          *
128          *      For each acknowledgement it sends, the HC-Receiver will add an
129          *      acknowledgement record.  ack_seqno will equal the HC-Receiver
130          *      sequence number it used for the ack packet; ack_ptr will equal
131          *      buf_head; ack_ackno will equal buf_ackno; and ack_nonce will
132          *      equal buf_nonce.
133          */
134         avr->avr_ack_seqno = DCCP_SKB_CB(skb)->dccpd_seq;
135         avr->avr_ack_ptr   = av->av_buf_head;
136         avr->avr_ack_ackno = av->av_buf_ackno;
137         avr->avr_ack_nonce = av->av_buf_nonce;
138         avr->avr_sent_len  = av->av_vec_len;
139
140         dccp_ackvec_insert_avr(av, avr);
141
142         dccp_pr_debug("%s ACK Vector 0, len=%d, ack_seqno=%llu, "
143                       "ack_ackno=%llu\n",
144                       dccp_role(sk), avr->avr_sent_len,
145                       (unsigned long long)avr->avr_ack_seqno,
146                       (unsigned long long)avr->avr_ack_ackno);
147         return 0;
148 }
149
150 struct dccp_ackvec *dccp_ackvec_alloc(const gfp_t priority)
151 {
152         struct dccp_ackvec *av = kmem_cache_alloc(dccp_ackvec_slab, priority);
153
154         if (av != NULL) {
155                 av->av_buf_head  = DCCP_MAX_ACKVEC_LEN - 1;
156                 av->av_buf_ackno = UINT48_MAX + 1;
157                 av->av_buf_nonce = 0;
158                 av->av_time      = ktime_set(0, 0);
159                 av->av_vec_len   = 0;
160                 INIT_LIST_HEAD(&av->av_records);
161         }
162
163         return av;
164 }
165
166 void dccp_ackvec_free(struct dccp_ackvec *av)
167 {
168         if (unlikely(av == NULL))
169                 return;
170
171         if (!list_empty(&av->av_records)) {
172                 struct dccp_ackvec_record *avr, *next;
173
174                 list_for_each_entry_safe(avr, next, &av->av_records, avr_node) {
175                         list_del_init(&avr->avr_node);
176                         dccp_ackvec_record_delete(avr);
177                 }
178         }
179
180         kmem_cache_free(dccp_ackvec_slab, av);
181 }
182
183 static inline u8 dccp_ackvec_state(const struct dccp_ackvec *av,
184                                    const u32 index)
185 {
186         return av->av_buf[index] & DCCP_ACKVEC_STATE_MASK;
187 }
188
189 static inline u8 dccp_ackvec_len(const struct dccp_ackvec *av,
190                                  const u32 index)
191 {
192         return av->av_buf[index] & DCCP_ACKVEC_LEN_MASK;
193 }
194
195 /*
196  * If several packets are missing, the HC-Receiver may prefer to enter multiple
197  * bytes with run length 0, rather than a single byte with a larger run length;
198  * this simplifies table updates if one of the missing packets arrives.
199  */
200 static inline int dccp_ackvec_set_buf_head_state(struct dccp_ackvec *av,
201                                                  const unsigned int packets,
202                                                  const unsigned char state)
203 {
204         unsigned int gap;
205         long new_head;
206
207         if (av->av_vec_len + packets > DCCP_MAX_ACKVEC_LEN)
208                 return -ENOBUFS;
209
210         gap      = packets - 1;
211         new_head = av->av_buf_head - packets;
212
213         if (new_head < 0) {
214                 if (gap > 0) {
215                         memset(av->av_buf, DCCP_ACKVEC_STATE_NOT_RECEIVED,
216                                gap + new_head + 1);
217                         gap = -new_head;
218                 }
219                 new_head += DCCP_MAX_ACKVEC_LEN;
220         }
221
222         av->av_buf_head = new_head;
223
224         if (gap > 0)
225                 memset(av->av_buf + av->av_buf_head + 1,
226                        DCCP_ACKVEC_STATE_NOT_RECEIVED, gap);
227
228         av->av_buf[av->av_buf_head] = state;
229         av->av_vec_len += packets;
230         return 0;
231 }
232
233 /*
234  * Implements the RFC 4340, Appendix A
235  */
236 int dccp_ackvec_add(struct dccp_ackvec *av, const struct sock *sk,
237                     const u64 ackno, const u8 state)
238 {
239         /*
240          * Check at the right places if the buffer is full, if it is, tell the
241          * caller to start dropping packets till the HC-Sender acks our ACK
242          * vectors, when we will free up space in av_buf.
243          *
244          * We may well decide to do buffer compression, etc, but for now lets
245          * just drop.
246          *
247          * From Appendix A.1.1 (`New Packets'):
248          *
249          *      Of course, the circular buffer may overflow, either when the
250          *      HC-Sender is sending data at a very high rate, when the
251          *      HC-Receiver's acknowledgements are not reaching the HC-Sender,
252          *      or when the HC-Sender is forgetting to acknowledge those acks
253          *      (so the HC-Receiver is unable to clean up old state). In this
254          *      case, the HC-Receiver should either compress the buffer (by
255          *      increasing run lengths when possible), transfer its state to
256          *      a larger buffer, or, as a last resort, drop all received
257          *      packets, without processing them whatsoever, until its buffer
258          *      shrinks again.
259          */
260
261         /* See if this is the first ackno being inserted */
262         if (av->av_vec_len == 0) {
263                 av->av_buf[av->av_buf_head] = state;
264                 av->av_vec_len = 1;
265         } else if (after48(ackno, av->av_buf_ackno)) {
266                 const u64 delta = dccp_delta_seqno(av->av_buf_ackno, ackno);
267
268                 /*
269                  * Look if the state of this packet is the same as the
270                  * previous ackno and if so if we can bump the head len.
271                  */
272                 if (delta == 1 &&
273                     dccp_ackvec_state(av, av->av_buf_head) == state &&
274                     dccp_ackvec_len(av, av->av_buf_head) < DCCP_ACKVEC_LEN_MASK)
275                         av->av_buf[av->av_buf_head]++;
276                 else if (dccp_ackvec_set_buf_head_state(av, delta, state))
277                         return -ENOBUFS;
278         } else {
279                 /*
280                  * A.1.2.  Old Packets
281                  *
282                  *      When a packet with Sequence Number S <= buf_ackno
283                  *      arrives, the HC-Receiver will scan the table for
284                  *      the byte corresponding to S. (Indexing structures
285                  *      could reduce the complexity of this scan.)
286                  */
287                 u64 delta = dccp_delta_seqno(ackno, av->av_buf_ackno);
288                 u32 index = av->av_buf_head;
289
290                 while (1) {
291                         const u8 len = dccp_ackvec_len(av, index);
292                         const u8 av_state = dccp_ackvec_state(av, index);
293                         /*
294                          * valid packets not yet in av_buf have a reserved
295                          * entry, with a len equal to 0.
296                          */
297                         if (av_state == DCCP_ACKVEC_STATE_NOT_RECEIVED &&
298                             len == 0 && delta == 0) { /* Found our
299                                                          reserved seat! */
300                                 dccp_pr_debug("Found %llu reserved seat!\n",
301                                               (unsigned long long)ackno);
302                                 av->av_buf[index] = state;
303                                 goto out;
304                         }
305                         /* len == 0 means one packet */
306                         if (delta < len + 1)
307                                 goto out_duplicate;
308
309                         delta -= len + 1;
310                         if (++index == DCCP_MAX_ACKVEC_LEN)
311                                 index = 0;
312                 }
313         }
314
315         av->av_buf_ackno = ackno;
316         av->av_time = ktime_get_real();
317 out:
318         return 0;
319
320 out_duplicate:
321         /* Duplicate packet */
322         dccp_pr_debug("Received a dup or already considered lost "
323                       "packet: %llu\n", (unsigned long long)ackno);
324         return -EILSEQ;
325 }
326
327 static void dccp_ackvec_throw_record(struct dccp_ackvec *av,
328                                      struct dccp_ackvec_record *avr)
329 {
330         struct dccp_ackvec_record *next;
331
332         /* sort out vector length */
333         if (av->av_buf_head <= avr->avr_ack_ptr)
334                 av->av_vec_len = avr->avr_ack_ptr - av->av_buf_head;
335         else
336                 av->av_vec_len = DCCP_MAX_ACKVEC_LEN - 1 -
337                                  av->av_buf_head + avr->avr_ack_ptr;
338
339         /* free records */
340         list_for_each_entry_safe_from(avr, next, &av->av_records, avr_node) {
341                 list_del_init(&avr->avr_node);
342                 dccp_ackvec_record_delete(avr);
343         }
344 }
345
346 void dccp_ackvec_check_rcv_ackno(struct dccp_ackvec *av, struct sock *sk,
347                                  const u64 ackno)
348 {
349         struct dccp_ackvec_record *avr;
350
351         /*
352          * If we traverse backwards, it should be faster when we have large
353          * windows. We will be receiving ACKs for stuff we sent a while back
354          * -sorbo.
355          */
356         list_for_each_entry_reverse(avr, &av->av_records, avr_node) {
357                 if (ackno == avr->avr_ack_seqno) {
358                         dccp_pr_debug("%s ACK packet 0, len=%d, ack_seqno=%llu, "
359                                       "ack_ackno=%llu, ACKED!\n",
360                                       dccp_role(sk), 1,
361                                       (unsigned long long)avr->avr_ack_seqno,
362                                       (unsigned long long)avr->avr_ack_ackno);
363                         dccp_ackvec_throw_record(av, avr);
364                         break;
365                 } else if (avr->avr_ack_seqno > ackno)
366                         break; /* old news */
367         }
368 }
369
370 static void dccp_ackvec_check_rcv_ackvector(struct dccp_ackvec *av,
371                                             struct sock *sk, u64 *ackno,
372                                             const unsigned char len,
373                                             const unsigned char *vector)
374 {
375         unsigned char i;
376         struct dccp_ackvec_record *avr;
377
378         /* Check if we actually sent an ACK vector */
379         if (list_empty(&av->av_records))
380                 return;
381
382         i = len;
383         /*
384          * XXX
385          * I think it might be more efficient to work backwards. See comment on
386          * rcv_ackno. -sorbo.
387          */
388         avr = list_entry(av->av_records.next, struct dccp_ackvec_record, avr_node);
389         while (i--) {
390                 const u8 rl = *vector & DCCP_ACKVEC_LEN_MASK;
391                 u64 ackno_end_rl;
392
393                 dccp_set_seqno(&ackno_end_rl, *ackno - rl);
394
395                 /*
396                  * If our AVR sequence number is greater than the ack, go
397                  * forward in the AVR list until it is not so.
398                  */
399                 list_for_each_entry_from(avr, &av->av_records, avr_node) {
400                         if (!after48(avr->avr_ack_seqno, *ackno))
401                                 goto found;
402                 }
403                 /* End of the av_records list, not found, exit */
404                 break;
405 found:
406                 if (between48(avr->avr_ack_seqno, ackno_end_rl, *ackno)) {
407                         const u8 state = *vector & DCCP_ACKVEC_STATE_MASK;
408                         if (state != DCCP_ACKVEC_STATE_NOT_RECEIVED) {
409                                 dccp_pr_debug("%s ACK vector 0, len=%d, "
410                                               "ack_seqno=%llu, ack_ackno=%llu, "
411                                               "ACKED!\n",
412                                               dccp_role(sk), len,
413                                               (unsigned long long)
414                                               avr->avr_ack_seqno,
415                                               (unsigned long long)
416                                               avr->avr_ack_ackno);
417                                 dccp_ackvec_throw_record(av, avr);
418                                 break;
419                         }
420                         /*
421                          * If it wasn't received, continue scanning... we might
422                          * find another one.
423                          */
424                 }
425
426                 dccp_set_seqno(ackno, ackno_end_rl - 1);
427                 ++vector;
428         }
429 }
430
431 int dccp_ackvec_parse(struct sock *sk, const struct sk_buff *skb,
432                       u64 *ackno, const u8 opt, const u8 *value, const u8 len)
433 {
434         if (len > DCCP_SINGLE_OPT_MAXLEN)
435                 return -1;
436
437         /* dccp_ackvector_print(DCCP_SKB_CB(skb)->dccpd_ack_seq, value, len); */
438         dccp_ackvec_check_rcv_ackvector(dccp_sk(sk)->dccps_hc_rx_ackvec, sk,
439                                         ackno, len, value);
440         return 0;
441 }
442
443 int __init dccp_ackvec_init(void)
444 {
445         dccp_ackvec_slab = kmem_cache_create("dccp_ackvec",
446                                              sizeof(struct dccp_ackvec), 0,
447                                              SLAB_HWCACHE_ALIGN, NULL);
448         if (dccp_ackvec_slab == NULL)
449                 goto out_err;
450
451         dccp_ackvec_record_slab =
452                         kmem_cache_create("dccp_ackvec_record",
453                                           sizeof(struct dccp_ackvec_record),
454                                           0, SLAB_HWCACHE_ALIGN, NULL);
455         if (dccp_ackvec_record_slab == NULL)
456                 goto out_destroy_slab;
457
458         return 0;
459
460 out_destroy_slab:
461         kmem_cache_destroy(dccp_ackvec_slab);
462         dccp_ackvec_slab = NULL;
463 out_err:
464         DCCP_CRIT("Unable to create Ack Vector slab cache");
465         return -ENOBUFS;
466 }
467
468 void dccp_ackvec_exit(void)
469 {
470         if (dccp_ackvec_slab != NULL) {
471                 kmem_cache_destroy(dccp_ackvec_slab);
472                 dccp_ackvec_slab = NULL;
473         }
474         if (dccp_ackvec_record_slab != NULL) {
475                 kmem_cache_destroy(dccp_ackvec_record_slab);
476                 dccp_ackvec_record_slab = NULL;
477         }
478 }