4 * An implementation of the DCCP protocol
5 * Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
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;
15 #include <linux/dccp.h>
16 #include <linux/init.h>
17 #include <linux/errno.h>
18 #include <linux/kernel.h>
19 #include <linux/skbuff.h>
20 #include <linux/slab.h>
24 static kmem_cache_t *dccp_ackvec_slab;
25 static kmem_cache_t *dccp_ackvec_record_slab;
27 static struct dccp_ackvec_record *dccp_ackvec_record_new(void)
29 struct dccp_ackvec_record *avr =
30 kmem_cache_alloc(dccp_ackvec_record_slab, GFP_ATOMIC);
33 INIT_LIST_HEAD(&avr->dccpavr_node);
38 static void dccp_ackvec_record_delete(struct dccp_ackvec_record *avr)
40 if (unlikely(avr == NULL))
42 /* Check if deleting a linked record */
43 WARN_ON(!list_empty(&avr->dccpavr_node));
44 kmem_cache_free(dccp_ackvec_record_slab, avr);
47 static void dccp_ackvec_insert_avr(struct dccp_ackvec *av,
48 struct dccp_ackvec_record *avr)
51 * AVRs are sorted by seqno. Since we are sending them in order, we
52 * just add the AVR at the head of the list.
55 if (!list_empty(&av->dccpav_records)) {
56 const struct dccp_ackvec_record *head =
57 list_entry(av->dccpav_records.next,
58 struct dccp_ackvec_record,
60 BUG_ON(before48(avr->dccpavr_ack_seqno,
61 head->dccpavr_ack_seqno));
64 list_add(&avr->dccpavr_node, &av->dccpav_records);
67 int dccp_insert_option_ackvec(struct sock *sk, struct sk_buff *skb)
69 struct dccp_sock *dp = dccp_sk(sk);
70 #ifdef CONFIG_IP_DCCP_DEBUG
71 const char *debug_prefix = dp->dccps_role == DCCP_ROLE_CLIENT ?
72 "CLIENT tx: " : "server tx: ";
74 struct dccp_ackvec *av = dp->dccps_hc_rx_ackvec;
75 int len = av->dccpav_vec_len + 2;
78 unsigned char *to, *from;
79 struct dccp_ackvec_record *avr;
81 if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)
84 avr = dccp_ackvec_record_new();
88 dccp_timestamp(sk, &now);
89 elapsed_time = timeval_delta(&now, &av->dccpav_time) / 10;
91 if (elapsed_time != 0)
92 dccp_insert_option_elapsed_time(sk, skb, elapsed_time);
94 DCCP_SKB_CB(skb)->dccpd_opt_len += len;
96 to = skb_push(skb, len);
97 *to++ = DCCPO_ACK_VECTOR_0;
100 len = av->dccpav_vec_len;
101 from = av->dccpav_buf + av->dccpav_buf_head;
103 /* Check if buf_head wraps */
104 if ((int)av->dccpav_buf_head + len > DCCP_MAX_ACKVEC_LEN) {
105 const u32 tailsize = DCCP_MAX_ACKVEC_LEN - av->dccpav_buf_head;
107 memcpy(to, from, tailsize);
110 from = av->dccpav_buf;
113 memcpy(to, from, len);
115 * From draft-ietf-dccp-spec-11.txt:
117 * For each acknowledgement it sends, the HC-Receiver will add an
118 * acknowledgement record. ack_seqno will equal the HC-Receiver
119 * sequence number it used for the ack packet; ack_ptr will equal
120 * buf_head; ack_ackno will equal buf_ackno; and ack_nonce will
123 avr->dccpavr_ack_seqno = DCCP_SKB_CB(skb)->dccpd_seq;
124 avr->dccpavr_ack_ptr = av->dccpav_buf_head;
125 avr->dccpavr_ack_ackno = av->dccpav_buf_ackno;
126 avr->dccpavr_ack_nonce = av->dccpav_buf_nonce;
127 avr->dccpavr_sent_len = av->dccpav_vec_len;
129 dccp_ackvec_insert_avr(av, avr);
131 dccp_pr_debug("%sACK Vector 0, len=%d, ack_seqno=%llu, "
133 debug_prefix, avr->dccpavr_sent_len,
134 (unsigned long long)avr->dccpavr_ack_seqno,
135 (unsigned long long)avr->dccpavr_ack_ackno);
139 struct dccp_ackvec *dccp_ackvec_alloc(const gfp_t priority)
141 struct dccp_ackvec *av = kmem_cache_alloc(dccp_ackvec_slab, priority);
144 av->dccpav_buf_head =
145 av->dccpav_buf_tail = DCCP_MAX_ACKVEC_LEN - 1;
146 av->dccpav_buf_ackno = DCCP_MAX_SEQNO + 1;
147 av->dccpav_buf_nonce = av->dccpav_buf_nonce = 0;
148 av->dccpav_ack_ptr = 0;
149 av->dccpav_time.tv_sec = 0;
150 av->dccpav_time.tv_usec = 0;
151 av->dccpav_sent_len = av->dccpav_vec_len = 0;
152 INIT_LIST_HEAD(&av->dccpav_records);
158 void dccp_ackvec_free(struct dccp_ackvec *av)
160 if (unlikely(av == NULL))
163 if (!list_empty(&av->dccpav_records)) {
164 struct dccp_ackvec_record *avr, *next;
166 list_for_each_entry_safe(avr, next, &av->dccpav_records,
168 list_del_init(&avr->dccpavr_node);
169 dccp_ackvec_record_delete(avr);
173 kmem_cache_free(dccp_ackvec_slab, av);
176 static inline u8 dccp_ackvec_state(const struct dccp_ackvec *av,
179 return av->dccpav_buf[index] & DCCP_ACKVEC_STATE_MASK;
182 static inline u8 dccp_ackvec_len(const struct dccp_ackvec *av,
185 return av->dccpav_buf[index] & DCCP_ACKVEC_LEN_MASK;
189 * If several packets are missing, the HC-Receiver may prefer to enter multiple
190 * bytes with run length 0, rather than a single byte with a larger run length;
191 * this simplifies table updates if one of the missing packets arrives.
193 static inline int dccp_ackvec_set_buf_head_state(struct dccp_ackvec *av,
194 const unsigned int packets,
195 const unsigned char state)
200 if (av->dccpav_vec_len + packets > DCCP_MAX_ACKVEC_LEN)
204 new_head = av->dccpav_buf_head - packets;
208 memset(av->dccpav_buf, DCCP_ACKVEC_STATE_NOT_RECEIVED,
212 new_head += DCCP_MAX_ACKVEC_LEN;
215 av->dccpav_buf_head = new_head;
218 memset(av->dccpav_buf + av->dccpav_buf_head + 1,
219 DCCP_ACKVEC_STATE_NOT_RECEIVED, gap);
221 av->dccpav_buf[av->dccpav_buf_head] = state;
222 av->dccpav_vec_len += packets;
227 * Implements the draft-ietf-dccp-spec-11.txt Appendix A
229 int dccp_ackvec_add(struct dccp_ackvec *av, const struct sock *sk,
230 const u64 ackno, const u8 state)
233 * Check at the right places if the buffer is full, if it is, tell the
234 * caller to start dropping packets till the HC-Sender acks our ACK
235 * vectors, when we will free up space in dccpav_buf.
237 * We may well decide to do buffer compression, etc, but for now lets
242 * Of course, the circular buffer may overflow, either when the
243 * HC-Sender is sending data at a very high rate, when the
244 * HC-Receiver's acknowledgements are not reaching the HC-Sender,
245 * or when the HC-Sender is forgetting to acknowledge those acks
246 * (so the HC-Receiver is unable to clean up old state). In this
247 * case, the HC-Receiver should either compress the buffer (by
248 * increasing run lengths when possible), transfer its state to
249 * a larger buffer, or, as a last resort, drop all received
250 * packets, without processing them whatsoever, until its buffer
254 /* See if this is the first ackno being inserted */
255 if (av->dccpav_vec_len == 0) {
256 av->dccpav_buf[av->dccpav_buf_head] = state;
257 av->dccpav_vec_len = 1;
258 } else if (after48(ackno, av->dccpav_buf_ackno)) {
259 const u64 delta = dccp_delta_seqno(av->dccpav_buf_ackno,
263 * Look if the state of this packet is the same as the
264 * previous ackno and if so if we can bump the head len.
267 dccp_ackvec_state(av, av->dccpav_buf_head) == state &&
268 (dccp_ackvec_len(av, av->dccpav_buf_head) <
269 DCCP_ACKVEC_LEN_MASK))
270 av->dccpav_buf[av->dccpav_buf_head]++;
271 else if (dccp_ackvec_set_buf_head_state(av, delta, state))
277 * When a packet with Sequence Number S arrives, and
278 * S <= buf_ackno, the HC-Receiver will scan the table
279 * for the byte corresponding to S. (Indexing structures
280 * could reduce the complexity of this scan.)
282 u64 delta = dccp_delta_seqno(ackno, av->dccpav_buf_ackno);
283 u8 index = av->dccpav_buf_head;
286 const u8 len = dccp_ackvec_len(av, index);
287 const u8 state = dccp_ackvec_state(av, index);
289 * valid packets not yet in dccpav_buf have a reserved
290 * entry, with a len equal to 0.
292 if (state == DCCP_ACKVEC_STATE_NOT_RECEIVED &&
293 len == 0 && delta == 0) { /* Found our
295 dccp_pr_debug("Found %llu reserved seat!\n",
296 (unsigned long long)ackno);
297 av->dccpav_buf[index] = state;
300 /* len == 0 means one packet */
305 if (++index == DCCP_MAX_ACKVEC_LEN)
310 av->dccpav_buf_ackno = ackno;
311 dccp_timestamp(sk, &av->dccpav_time);
317 /* Duplicate packet */
318 dccp_pr_debug("Received a dup or already considered lost "
319 "packet: %llu\n", (unsigned long long)ackno);
323 #ifdef CONFIG_IP_DCCP_DEBUG
324 void dccp_ackvector_print(const u64 ackno, const unsigned char *vector, int len)
329 printk("ACK vector len=%d, ackno=%llu |", len,
330 (unsigned long long)ackno);
333 const u8 state = (*vector & DCCP_ACKVEC_STATE_MASK) >> 6;
334 const u8 rl = *vector & DCCP_ACKVEC_LEN_MASK;
336 printk("%d,%d|", state, rl);
343 void dccp_ackvec_print(const struct dccp_ackvec *av)
345 dccp_ackvector_print(av->dccpav_buf_ackno,
346 av->dccpav_buf + av->dccpav_buf_head,
351 static void dccp_ackvec_throw_record(struct dccp_ackvec *av,
352 struct dccp_ackvec_record *avr)
354 struct dccp_ackvec_record *next;
356 av->dccpav_buf_tail = avr->dccpavr_ack_ptr - 1;
357 if (av->dccpav_buf_tail == 0)
358 av->dccpav_buf_tail = DCCP_MAX_ACKVEC_LEN - 1;
360 av->dccpav_vec_len -= avr->dccpavr_sent_len;
363 list_for_each_entry_safe_from(avr, next, &av->dccpav_records,
365 list_del_init(&avr->dccpavr_node);
366 dccp_ackvec_record_delete(avr);
370 void dccp_ackvec_check_rcv_ackno(struct dccp_ackvec *av, struct sock *sk,
373 struct dccp_ackvec_record *avr;
376 * If we traverse backwards, it should be faster when we have large
377 * windows. We will be receiving ACKs for stuff we sent a while back
380 list_for_each_entry_reverse(avr, &av->dccpav_records, dccpavr_node) {
381 if (ackno == avr->dccpavr_ack_seqno) {
382 #ifdef CONFIG_IP_DCCP_DEBUG
383 struct dccp_sock *dp = dccp_sk(sk);
384 const char *debug_prefix = dp->dccps_role == DCCP_ROLE_CLIENT ?
385 "CLIENT rx ack: " : "server rx ack: ";
387 dccp_pr_debug("%sACK packet 0, len=%d, ack_seqno=%llu, "
388 "ack_ackno=%llu, ACKED!\n",
390 (unsigned long long)avr->dccpavr_ack_seqno,
391 (unsigned long long)avr->dccpavr_ack_ackno);
392 dccp_ackvec_throw_record(av, avr);
398 static void dccp_ackvec_check_rcv_ackvector(struct dccp_ackvec *av,
399 struct sock *sk, u64 ackno,
400 const unsigned char len,
401 const unsigned char *vector)
404 struct dccp_ackvec_record *avr;
406 /* Check if we actually sent an ACK vector */
407 if (list_empty(&av->dccpav_records))
413 * I think it might be more efficient to work backwards. See comment on
416 avr = list_entry(av->dccpav_records.next, struct dccp_ackvec_record,
419 const u8 rl = *vector & DCCP_ACKVEC_LEN_MASK;
422 dccp_set_seqno(&ackno_end_rl, ackno - rl);
425 * If our AVR sequence number is greater than the ack, go
426 * forward in the AVR list until it is not so.
428 list_for_each_entry_from(avr, &av->dccpav_records,
430 if (!after48(avr->dccpavr_ack_seqno, ackno))
433 /* End of the dccpav_records list, not found, exit */
436 if (between48(avr->dccpavr_ack_seqno, ackno_end_rl, ackno)) {
437 const u8 state = (*vector &
438 DCCP_ACKVEC_STATE_MASK) >> 6;
439 if (state != DCCP_ACKVEC_STATE_NOT_RECEIVED) {
440 #ifdef CONFIG_IP_DCCP_DEBUG
441 struct dccp_sock *dp = dccp_sk(sk);
442 const char *debug_prefix =
443 dp->dccps_role == DCCP_ROLE_CLIENT ?
444 "CLIENT rx ack: " : "server rx ack: ";
446 dccp_pr_debug("%sACK vector 0, len=%d, "
447 "ack_seqno=%llu, ack_ackno=%llu, "
451 avr->dccpavr_ack_seqno,
453 avr->dccpavr_ack_ackno);
454 dccp_ackvec_throw_record(av, avr);
457 * If it wasn't received, continue scanning... we might
462 dccp_set_seqno(&ackno, ackno_end_rl - 1);
467 int dccp_ackvec_parse(struct sock *sk, const struct sk_buff *skb,
468 const u8 opt, const u8 *value, const u8 len)
470 if (len > DCCP_MAX_ACKVEC_LEN)
473 /* dccp_ackvector_print(DCCP_SKB_CB(skb)->dccpd_ack_seq, value, len); */
474 dccp_ackvec_check_rcv_ackvector(dccp_sk(sk)->dccps_hc_rx_ackvec, sk,
475 DCCP_SKB_CB(skb)->dccpd_ack_seq,
480 static char dccp_ackvec_slab_msg[] __initdata =
481 KERN_CRIT "DCCP: Unable to create ack vectors slab caches\n";
483 int __init dccp_ackvec_init(void)
485 dccp_ackvec_slab = kmem_cache_create("dccp_ackvec",
486 sizeof(struct dccp_ackvec), 0,
487 SLAB_HWCACHE_ALIGN, NULL, NULL);
488 if (dccp_ackvec_slab == NULL)
491 dccp_ackvec_record_slab =
492 kmem_cache_create("dccp_ackvec_record",
493 sizeof(struct dccp_ackvec_record),
494 0, SLAB_HWCACHE_ALIGN, NULL, NULL);
495 if (dccp_ackvec_record_slab == NULL)
496 goto out_destroy_slab;
501 kmem_cache_destroy(dccp_ackvec_slab);
502 dccp_ackvec_slab = NULL;
504 printk(dccp_ackvec_slab_msg);
508 void dccp_ackvec_exit(void)
510 if (dccp_ackvec_slab != NULL) {
511 kmem_cache_destroy(dccp_ackvec_slab);
512 dccp_ackvec_slab = NULL;
514 if (dccp_ackvec_record_slab != NULL) {
515 kmem_cache_destroy(dccp_ackvec_record_slab);
516 dccp_ackvec_record_slab = NULL;