[DCCP] ackvec: Fix spelling of "throw"
[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/dccp.h>
16 #include <linux/skbuff.h>
17
18 #include <net/sock.h>
19
20 int 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
93 struct dccp_ackvec *dccp_ackvec_alloc(const unsigned int len,
94                                       const gfp_t priority)
95 {
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
114 void dccp_ackvec_free(struct dccp_ackvec *av)
115 {
116         kfree(av);
117 }
118
119 static 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
125 static 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  */
136 static 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  */
172 int 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);
255 out:
256         dccp_pr_debug("");
257         return 0;
258
259 out_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
267 void 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
286 void 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
294 static void dccp_ackvec_throw_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
311 void 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_throw_away_ack_record(av);
330                 av->dccpav_ack_seqno = DCCP_MAX_SEQNO + 1;
331         }
332 }
333
334 static 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_throw_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
408 int 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 }