[DCCP]: Update documentation references.
[linux-2.6.git] / net / dccp / options.c
1 /*
2  *  net/dccp/options.c
3  *
4  *  An implementation of the DCCP protocol
5  *  Copyright (c) 2005 Aristeu Sergio Rozanski Filho <aris@cathedrallabs.org>
6  *  Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
7  *  Copyright (c) 2005 Ian McDonald <ian.mcdonald@jandi.co.nz>
8  *
9  *      This program is free software; you can redistribute it and/or
10  *      modify it under the terms of the GNU General Public License
11  *      as published by the Free Software Foundation; either version
12  *      2 of the License, or (at your option) any later version.
13  */
14 #include <linux/dccp.h>
15 #include <linux/module.h>
16 #include <linux/types.h>
17 #include <linux/kernel.h>
18 #include <linux/skbuff.h>
19
20 #include "ackvec.h"
21 #include "ccid.h"
22 #include "dccp.h"
23 #include "feat.h"
24
25 int dccp_feat_default_sequence_window = DCCPF_INITIAL_SEQUENCE_WINDOW;
26 int dccp_feat_default_rx_ccid         = DCCPF_INITIAL_CCID;
27 int dccp_feat_default_tx_ccid         = DCCPF_INITIAL_CCID;
28 int dccp_feat_default_ack_ratio       = DCCPF_INITIAL_ACK_RATIO;
29 int dccp_feat_default_send_ack_vector = DCCPF_INITIAL_SEND_ACK_VECTOR;
30 int dccp_feat_default_send_ndp_count  = DCCPF_INITIAL_SEND_NDP_COUNT;
31
32 EXPORT_SYMBOL_GPL(dccp_feat_default_sequence_window);
33
34 void dccp_minisock_init(struct dccp_minisock *dmsk)
35 {
36         dmsk->dccpms_sequence_window = dccp_feat_default_sequence_window;
37         dmsk->dccpms_rx_ccid         = dccp_feat_default_rx_ccid;
38         dmsk->dccpms_tx_ccid         = dccp_feat_default_tx_ccid;
39         dmsk->dccpms_ack_ratio       = dccp_feat_default_ack_ratio;
40         dmsk->dccpms_send_ack_vector = dccp_feat_default_send_ack_vector;
41         dmsk->dccpms_send_ndp_count  = dccp_feat_default_send_ndp_count;
42 }
43
44 static u32 dccp_decode_value_var(const unsigned char *bf, const u8 len)
45 {
46         u32 value = 0;
47
48         if (len > 3)
49                 value += *bf++ << 24;
50         if (len > 2)
51                 value += *bf++ << 16;
52         if (len > 1)
53                 value += *bf++ << 8;
54         if (len > 0)
55                 value += *bf;
56
57         return value;
58 }
59
60 int dccp_parse_options(struct sock *sk, struct sk_buff *skb)
61 {
62         struct dccp_sock *dp = dccp_sk(sk);
63 #ifdef CONFIG_IP_DCCP_DEBUG
64         const char *debug_prefix = dp->dccps_role == DCCP_ROLE_CLIENT ?
65                                         "CLIENT rx opt: " : "server rx opt: ";
66 #endif
67         const struct dccp_hdr *dh = dccp_hdr(skb);
68         const u8 pkt_type = DCCP_SKB_CB(skb)->dccpd_type;
69         unsigned char *options = (unsigned char *)dh + dccp_hdr_len(skb);
70         unsigned char *opt_ptr = options;
71         const unsigned char *opt_end = (unsigned char *)dh +
72                                         (dh->dccph_doff * 4);
73         struct dccp_options_received *opt_recv = &dp->dccps_options_received;
74         unsigned char opt, len;
75         unsigned char *value;
76         u32 elapsed_time;
77         int rc;
78         int mandatory = 0;
79
80         memset(opt_recv, 0, sizeof(*opt_recv));
81
82         opt = len = 0;
83         while (opt_ptr != opt_end) {
84                 opt   = *opt_ptr++;
85                 len   = 0;
86                 value = NULL;
87
88                 /* Check if this isn't a single byte option */
89                 if (opt > DCCPO_MAX_RESERVED) {
90                         if (opt_ptr == opt_end)
91                                 goto out_invalid_option;
92
93                         len = *opt_ptr++;
94                         if (len < 3)
95                                 goto out_invalid_option;
96                         /*
97                          * Remove the type and len fields, leaving
98                          * just the value size
99                          */
100                         len     -= 2;
101                         value   = opt_ptr;
102                         opt_ptr += len;
103
104                         if (opt_ptr > opt_end)
105                                 goto out_invalid_option;
106                 }
107
108                 switch (opt) {
109                 case DCCPO_PADDING:
110                         break;
111                 case DCCPO_MANDATORY:
112                         if (mandatory)
113                                 goto out_invalid_option;
114                         if (pkt_type != DCCP_PKT_DATA)
115                                 mandatory = 1;
116                         break;
117                 case DCCPO_NDP_COUNT:
118                         if (len > 3)
119                                 goto out_invalid_option;
120
121                         opt_recv->dccpor_ndp = dccp_decode_value_var(value, len);
122                         dccp_pr_debug("%sNDP count=%d\n", debug_prefix,
123                                       opt_recv->dccpor_ndp);
124                         break;
125                 case DCCPO_CHANGE_L:
126                         /* fall through */
127                 case DCCPO_CHANGE_R:
128                         if (len < 2)
129                                 goto out_invalid_option;
130                         rc = dccp_feat_change_recv(sk, opt, *value, value + 1,
131                                                    len - 1);
132                         /*
133                          * When there is a change error, change_recv is
134                          * responsible for dealing with it.  i.e. reply with an
135                          * empty confirm.
136                          * If the change was mandatory, then we need to die.
137                          */
138                         if (rc && mandatory)
139                                 goto out_invalid_option;
140                         break;
141                 case DCCPO_CONFIRM_L:
142                         /* fall through */
143                 case DCCPO_CONFIRM_R:
144                         if (len < 2)
145                                 goto out_invalid_option;
146                         if (dccp_feat_confirm_recv(sk, opt, *value,
147                                                    value + 1, len - 1))
148                                 goto out_invalid_option;
149                         break;
150                 case DCCPO_ACK_VECTOR_0:
151                 case DCCPO_ACK_VECTOR_1:
152                         if (pkt_type == DCCP_PKT_DATA)
153                                 break;
154
155                         if (dccp_msk(sk)->dccpms_send_ack_vector &&
156                             dccp_ackvec_parse(sk, skb, opt, value, len))
157                                 goto out_invalid_option;
158                         break;
159                 case DCCPO_TIMESTAMP:
160                         if (len != 4)
161                                 goto out_invalid_option;
162
163                         opt_recv->dccpor_timestamp = ntohl(*(__be32 *)value);
164
165                         dp->dccps_timestamp_echo = opt_recv->dccpor_timestamp;
166                         dccp_timestamp(sk, &dp->dccps_timestamp_time);
167
168                         dccp_pr_debug("%sTIMESTAMP=%u, ackno=%llu\n",
169                                       debug_prefix, opt_recv->dccpor_timestamp,
170                                       (unsigned long long)
171                                       DCCP_SKB_CB(skb)->dccpd_ack_seq);
172                         break;
173                 case DCCPO_TIMESTAMP_ECHO:
174                         if (len != 4 && len != 6 && len != 8)
175                                 goto out_invalid_option;
176
177                         opt_recv->dccpor_timestamp_echo = ntohl(*(__be32 *)value);
178
179                         dccp_pr_debug("%sTIMESTAMP_ECHO=%u, len=%d, ackno=%llu, ",
180                                       debug_prefix,
181                                       opt_recv->dccpor_timestamp_echo,
182                                       len + 2,
183                                       (unsigned long long)
184                                       DCCP_SKB_CB(skb)->dccpd_ack_seq);
185
186
187                         if (len == 4)
188                                 break;
189
190                         if (len == 6)
191                                 elapsed_time = ntohs(*(__be16 *)(value + 4));
192                         else
193                                 elapsed_time = ntohl(*(__be32 *)(value + 4));
194
195                         /* Give precedence to the biggest ELAPSED_TIME */
196                         if (elapsed_time > opt_recv->dccpor_elapsed_time)
197                                 opt_recv->dccpor_elapsed_time = elapsed_time;
198                         break;
199                 case DCCPO_ELAPSED_TIME:
200                         if (len != 2 && len != 4)
201                                 goto out_invalid_option;
202
203                         if (pkt_type == DCCP_PKT_DATA)
204                                 continue;
205
206                         if (len == 2)
207                                 elapsed_time = ntohs(*(__be16 *)value);
208                         else
209                                 elapsed_time = ntohl(*(__be32 *)value);
210
211                         if (elapsed_time > opt_recv->dccpor_elapsed_time)
212                                 opt_recv->dccpor_elapsed_time = elapsed_time;
213
214                         dccp_pr_debug("%sELAPSED_TIME=%d\n", debug_prefix,
215                                       elapsed_time);
216                         break;
217                         /*
218                          * From RFC 4340, sec. 10.3:
219                          *
220                          *      Option numbers 128 through 191 are for
221                          *      options sent from the HC-Sender to the
222                          *      HC-Receiver; option numbers 192 through 255
223                          *      are for options sent from the HC-Receiver to
224                          *      the HC-Sender.
225                          */
226                 case 128 ... 191: {
227                         const u16 idx = value - options;
228
229                         if (ccid_hc_rx_parse_options(dp->dccps_hc_rx_ccid, sk,
230                                                      opt, len, idx,
231                                                      value) != 0)
232                                 goto out_invalid_option;
233                 }
234                         break;
235                 case 192 ... 255: {
236                         const u16 idx = value - options;
237
238                         if (ccid_hc_tx_parse_options(dp->dccps_hc_tx_ccid, sk,
239                                                      opt, len, idx,
240                                                      value) != 0)
241                                 goto out_invalid_option;
242                 }
243                         break;
244                 default:
245                         pr_info("DCCP(%p): option %d(len=%d) not "
246                                 "implemented, ignoring\n",
247                                 sk, opt, len);
248                         break;
249                 }
250
251                 if (opt != DCCPO_MANDATORY)
252                         mandatory = 0;
253         }
254
255         /* mandatory was the last byte in option list -> reset connection */
256         if (mandatory)
257                 goto out_invalid_option;
258
259         return 0;
260
261 out_invalid_option:
262         DCCP_INC_STATS_BH(DCCP_MIB_INVALIDOPT);
263         DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_OPTION_ERROR;
264         pr_info("DCCP(%p): invalid option %d, len=%d\n", sk, opt, len);
265         return -1;
266 }
267
268 EXPORT_SYMBOL_GPL(dccp_parse_options);
269
270 static void dccp_encode_value_var(const u32 value, unsigned char *to,
271                                   const unsigned int len)
272 {
273         if (len > 3)
274                 *to++ = (value & 0xFF000000) >> 24;
275         if (len > 2)
276                 *to++ = (value & 0xFF0000) >> 16;
277         if (len > 1)
278                 *to++ = (value & 0xFF00) >> 8;
279         if (len > 0)
280                 *to++ = (value & 0xFF);
281 }
282
283 static inline int dccp_ndp_len(const int ndp)
284 {
285         return likely(ndp <= 0xFF) ? 1 : ndp <= 0xFFFF ? 2 : 3;
286 }
287
288 int dccp_insert_option(struct sock *sk, struct sk_buff *skb,
289                         const unsigned char option,
290                         const void *value, const unsigned char len)
291 {
292         unsigned char *to;
293
294         if (DCCP_SKB_CB(skb)->dccpd_opt_len + len + 2 > DCCP_MAX_OPT_LEN)
295                 return -1;
296
297         DCCP_SKB_CB(skb)->dccpd_opt_len += len + 2;
298
299         to    = skb_push(skb, len + 2);
300         *to++ = option;
301         *to++ = len + 2;
302
303         memcpy(to, value, len);
304         return 0;
305 }
306
307 EXPORT_SYMBOL_GPL(dccp_insert_option);
308
309 static int dccp_insert_option_ndp(struct sock *sk, struct sk_buff *skb)
310 {
311         struct dccp_sock *dp = dccp_sk(sk);
312         int ndp = dp->dccps_ndp_count;
313
314         if (dccp_non_data_packet(skb))
315                 ++dp->dccps_ndp_count;
316         else
317                 dp->dccps_ndp_count = 0;
318
319         if (ndp > 0) {
320                 unsigned char *ptr;
321                 const int ndp_len = dccp_ndp_len(ndp);
322                 const int len = ndp_len + 2;
323
324                 if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)
325                         return -1;
326
327                 DCCP_SKB_CB(skb)->dccpd_opt_len += len;
328
329                 ptr = skb_push(skb, len);
330                 *ptr++ = DCCPO_NDP_COUNT;
331                 *ptr++ = len;
332                 dccp_encode_value_var(ndp, ptr, ndp_len);
333         }
334
335         return 0;
336 }
337
338 static inline int dccp_elapsed_time_len(const u32 elapsed_time)
339 {
340         return elapsed_time == 0 ? 0 : elapsed_time <= 0xFFFF ? 2 : 4;
341 }
342
343 int dccp_insert_option_elapsed_time(struct sock *sk, struct sk_buff *skb,
344                                     u32 elapsed_time)
345 {
346         const int elapsed_time_len = dccp_elapsed_time_len(elapsed_time);
347         const int len = 2 + elapsed_time_len;
348         unsigned char *to;
349
350         if (elapsed_time_len == 0)
351                 return 0;
352
353         if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)
354                 return -1;
355
356         DCCP_SKB_CB(skb)->dccpd_opt_len += len;
357
358         to    = skb_push(skb, len);
359         *to++ = DCCPO_ELAPSED_TIME;
360         *to++ = len;
361
362         if (elapsed_time_len == 2) {
363                 const __be16 var16 = htons((u16)elapsed_time);
364                 memcpy(to, &var16, 2);
365         } else {
366                 const __be32 var32 = htonl(elapsed_time);
367                 memcpy(to, &var32, 4);
368         }
369
370         return 0;
371 }
372
373 EXPORT_SYMBOL_GPL(dccp_insert_option_elapsed_time);
374
375 void dccp_timestamp(const struct sock *sk, struct timeval *tv)
376 {
377         const struct dccp_sock *dp = dccp_sk(sk);
378
379         do_gettimeofday(tv);
380         tv->tv_sec  -= dp->dccps_epoch.tv_sec;
381         tv->tv_usec -= dp->dccps_epoch.tv_usec;
382
383         while (tv->tv_usec < 0) {
384                 tv->tv_sec--;
385                 tv->tv_usec += USEC_PER_SEC;
386         }
387 }
388
389 EXPORT_SYMBOL_GPL(dccp_timestamp);
390
391 int dccp_insert_option_timestamp(struct sock *sk, struct sk_buff *skb)
392 {
393         struct timeval tv;
394         __be32 now;
395
396         dccp_timestamp(sk, &tv);
397         now = htonl(timeval_usecs(&tv) / 10);
398         /* yes this will overflow but that is the point as we want a
399          * 10 usec 32 bit timer which mean it wraps every 11.9 hours */
400
401         return dccp_insert_option(sk, skb, DCCPO_TIMESTAMP, &now, sizeof(now));
402 }
403
404 EXPORT_SYMBOL_GPL(dccp_insert_option_timestamp);
405
406 static int dccp_insert_option_timestamp_echo(struct sock *sk,
407                                              struct sk_buff *skb)
408 {
409         struct dccp_sock *dp = dccp_sk(sk);
410         struct timeval now;
411         __be32 tstamp_echo;
412         u32 elapsed_time;
413         int len, elapsed_time_len;
414         unsigned char *to;
415
416         dccp_timestamp(sk, &now);
417         elapsed_time = timeval_delta(&now, &dp->dccps_timestamp_time) / 10;
418         elapsed_time_len = dccp_elapsed_time_len(elapsed_time);
419         len = 6 + elapsed_time_len;
420
421         if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)
422                 return -1;
423
424         DCCP_SKB_CB(skb)->dccpd_opt_len += len;
425
426         to    = skb_push(skb, len);
427         *to++ = DCCPO_TIMESTAMP_ECHO;
428         *to++ = len;
429
430         tstamp_echo = htonl(dp->dccps_timestamp_echo);
431         memcpy(to, &tstamp_echo, 4);
432         to += 4;
433
434         if (elapsed_time_len == 2) {
435                 const __be16 var16 = htons((u16)elapsed_time);
436                 memcpy(to, &var16, 2);
437         } else if (elapsed_time_len == 4) {
438                 const __be32 var32 = htonl(elapsed_time);
439                 memcpy(to, &var32, 4);
440         }
441
442         dp->dccps_timestamp_echo = 0;
443         dp->dccps_timestamp_time.tv_sec = 0;
444         dp->dccps_timestamp_time.tv_usec = 0;
445         return 0;
446 }
447
448 static int dccp_insert_feat_opt(struct sk_buff *skb, u8 type, u8 feat,
449                                 u8 *val, u8 len)
450 {
451         u8 *to;
452
453         if (DCCP_SKB_CB(skb)->dccpd_opt_len + len + 3 > DCCP_MAX_OPT_LEN) {
454                 LIMIT_NETDEBUG(KERN_INFO "DCCP: packet too small"
455                                " to insert feature %d option!\n", feat);
456                 return -1;
457         }
458
459         DCCP_SKB_CB(skb)->dccpd_opt_len += len + 3;
460
461         to    = skb_push(skb, len + 3);
462         *to++ = type;
463         *to++ = len + 3;
464         *to++ = feat;
465
466         if (len)
467                 memcpy(to, val, len);
468         dccp_pr_debug("option %d feat %d len %d\n", type, feat, len);
469
470         return 0;
471 }
472
473 static int dccp_insert_options_feat(struct sock *sk, struct sk_buff *skb)
474 {
475         struct dccp_sock *dp = dccp_sk(sk);
476         struct dccp_minisock *dmsk = dccp_msk(sk);
477         struct dccp_opt_pend *opt, *next;
478         int change = 0;
479
480         /* confirm any options [NN opts] */
481         list_for_each_entry_safe(opt, next, &dmsk->dccpms_conf, dccpop_node) {
482                 dccp_insert_feat_opt(skb, opt->dccpop_type,
483                                      opt->dccpop_feat, opt->dccpop_val,
484                                      opt->dccpop_len);
485                 /* fear empty confirms */
486                 if (opt->dccpop_val)
487                         kfree(opt->dccpop_val);
488                 kfree(opt);
489         }
490         INIT_LIST_HEAD(&dmsk->dccpms_conf);
491
492         /* see which features we need to send */
493         list_for_each_entry(opt, &dmsk->dccpms_pending, dccpop_node) {
494                 /* see if we need to send any confirm */
495                 if (opt->dccpop_sc) {
496                         dccp_insert_feat_opt(skb, opt->dccpop_type + 1,
497                                              opt->dccpop_feat,
498                                              opt->dccpop_sc->dccpoc_val,
499                                              opt->dccpop_sc->dccpoc_len);
500
501                         BUG_ON(!opt->dccpop_sc->dccpoc_val);
502                         kfree(opt->dccpop_sc->dccpoc_val);
503                         kfree(opt->dccpop_sc);
504                         opt->dccpop_sc = NULL;
505                 }
506
507                 /* any option not confirmed, re-send it */
508                 if (!opt->dccpop_conf) {
509                         dccp_insert_feat_opt(skb, opt->dccpop_type,
510                                              opt->dccpop_feat, opt->dccpop_val,
511                                              opt->dccpop_len);
512                         change++;
513                 }
514         }
515
516         /* Retransmit timer.
517          * If this is the master listening sock, we don't set a timer on it.  It
518          * should be fine because if the dude doesn't receive our RESPONSE
519          * [which will contain the CHANGE] he will send another REQUEST which
520          * will "retrnasmit" the change.
521          */
522         if (change && dp->dccps_role != DCCP_ROLE_LISTEN) {
523                 dccp_pr_debug("reset feat negotiation timer %p\n", sk);
524
525                 /* XXX don't reset the timer on re-transmissions.  I.e. reset it
526                  * only when sending new stuff i guess.  Currently the timer
527                  * never backs off because on re-transmission it just resets it!
528                  */
529                 inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
530                                           inet_csk(sk)->icsk_rto, DCCP_RTO_MAX);
531         }
532
533         return 0;
534 }
535
536 int dccp_insert_options(struct sock *sk, struct sk_buff *skb)
537 {
538         struct dccp_sock *dp = dccp_sk(sk);
539         struct dccp_minisock *dmsk = dccp_msk(sk);
540
541         DCCP_SKB_CB(skb)->dccpd_opt_len = 0;
542
543         if (dmsk->dccpms_send_ndp_count &&
544             dccp_insert_option_ndp(sk, skb))
545                 return -1;
546
547         if (!dccp_packet_without_ack(skb)) {
548                 if (dmsk->dccpms_send_ack_vector &&
549                     dccp_ackvec_pending(dp->dccps_hc_rx_ackvec) &&
550                     dccp_insert_option_ackvec(sk, skb))
551                         return -1;
552
553                 if (dp->dccps_timestamp_echo != 0 &&
554                     dccp_insert_option_timestamp_echo(sk, skb))
555                         return -1;
556         }
557
558         if (dp->dccps_hc_rx_insert_options) {
559                 if (ccid_hc_rx_insert_options(dp->dccps_hc_rx_ccid, sk, skb))
560                         return -1;
561                 dp->dccps_hc_rx_insert_options = 0;
562         }
563         if (dp->dccps_hc_tx_insert_options) {
564                 if (ccid_hc_tx_insert_options(dp->dccps_hc_tx_ccid, sk, skb))
565                         return -1;
566                 dp->dccps_hc_tx_insert_options = 0;
567         }
568
569         /* Feature negotiation */
570         /* Data packets can't do feat negotiation */
571         if (DCCP_SKB_CB(skb)->dccpd_type != DCCP_PKT_DATA &&
572             DCCP_SKB_CB(skb)->dccpd_type != DCCP_PKT_DATAACK &&
573             dccp_insert_options_feat(sk, skb))
574                 return -1;
575
576         /* XXX: insert other options when appropriate */
577
578         if (DCCP_SKB_CB(skb)->dccpd_opt_len != 0) {
579                 /* The length of all options has to be a multiple of 4 */
580                 int padding = DCCP_SKB_CB(skb)->dccpd_opt_len % 4;
581
582                 if (padding != 0) {
583                         padding = 4 - padding;
584                         memset(skb_push(skb, padding), 0, padding);
585                         DCCP_SKB_CB(skb)->dccpd_opt_len += padding;
586                 }
587         }
588
589         return 0;
590 }