dccp ccid-2: Separate internals of Ack Vectors from option-parsing code
[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 <asm/unaligned.h>
18 #include <linux/kernel.h>
19 #include <linux/skbuff.h>
20
21 #include "ackvec.h"
22 #include "ccid.h"
23 #include "dccp.h"
24 #include "feat.h"
25
26 u64 dccp_decode_value_var(const u8 *bf, const u8 len)
27 {
28         u64 value = 0;
29
30         if (len >= DCCP_OPTVAL_MAXLEN)
31                 value += ((u64)*bf++) << 40;
32         if (len > 4)
33                 value += ((u64)*bf++) << 32;
34         if (len > 3)
35                 value += ((u64)*bf++) << 24;
36         if (len > 2)
37                 value += ((u64)*bf++) << 16;
38         if (len > 1)
39                 value += ((u64)*bf++) << 8;
40         if (len > 0)
41                 value += *bf;
42
43         return value;
44 }
45
46 /**
47  * dccp_parse_options  -  Parse DCCP options present in @skb
48  * @sk: client|server|listening dccp socket (when @dreq != NULL)
49  * @dreq: request socket to use during connection setup, or NULL
50  */
51 int dccp_parse_options(struct sock *sk, struct dccp_request_sock *dreq,
52                        struct sk_buff *skb)
53 {
54         struct dccp_sock *dp = dccp_sk(sk);
55         const struct dccp_hdr *dh = dccp_hdr(skb);
56         const u8 pkt_type = DCCP_SKB_CB(skb)->dccpd_type;
57         u64 ackno = DCCP_SKB_CB(skb)->dccpd_ack_seq;
58         unsigned char *options = (unsigned char *)dh + dccp_hdr_len(skb);
59         unsigned char *opt_ptr = options;
60         const unsigned char *opt_end = (unsigned char *)dh +
61                                         (dh->dccph_doff * 4);
62         struct dccp_options_received *opt_recv = &dp->dccps_options_received;
63         unsigned char opt, len;
64         unsigned char *uninitialized_var(value);
65         u32 elapsed_time;
66         __be32 opt_val;
67         int rc;
68         int mandatory = 0;
69
70         memset(opt_recv, 0, sizeof(*opt_recv));
71
72         opt = len = 0;
73         while (opt_ptr != opt_end) {
74                 opt   = *opt_ptr++;
75                 len   = 0;
76                 value = NULL;
77
78                 /* Check if this isn't a single byte option */
79                 if (opt > DCCPO_MAX_RESERVED) {
80                         if (opt_ptr == opt_end)
81                                 goto out_nonsensical_length;
82
83                         len = *opt_ptr++;
84                         if (len < 2)
85                                 goto out_nonsensical_length;
86                         /*
87                          * Remove the type and len fields, leaving
88                          * just the value size
89                          */
90                         len     -= 2;
91                         value   = opt_ptr;
92                         opt_ptr += len;
93
94                         if (opt_ptr > opt_end)
95                                 goto out_nonsensical_length;
96                 }
97
98                 /*
99                  * CCID-specific options are ignored during connection setup, as
100                  * negotiation may still be in progress (see RFC 4340, 10.3).
101                  * The same applies to Ack Vectors, as these depend on the CCID.
102                  */
103                 if (dreq != NULL && (opt >= DCCPO_MIN_RX_CCID_SPECIFIC ||
104                     opt == DCCPO_ACK_VECTOR_0 || opt == DCCPO_ACK_VECTOR_1))
105                         goto ignore_option;
106
107                 switch (opt) {
108                 case DCCPO_PADDING:
109                         break;
110                 case DCCPO_MANDATORY:
111                         if (mandatory)
112                                 goto out_invalid_option;
113                         if (pkt_type != DCCP_PKT_DATA)
114                                 mandatory = 1;
115                         break;
116                 case DCCPO_NDP_COUNT:
117                         if (len > 6)
118                                 goto out_invalid_option;
119
120                         opt_recv->dccpor_ndp = dccp_decode_value_var(value, len);
121                         dccp_pr_debug("%s opt: NDP count=%llu\n", dccp_role(sk),
122                                       (unsigned long long)opt_recv->dccpor_ndp);
123                         break;
124                 case DCCPO_CHANGE_L ... DCCPO_CONFIRM_R:
125                         if (pkt_type == DCCP_PKT_DATA)      /* RFC 4340, 6 */
126                                 break;
127                         rc = dccp_feat_parse_options(sk, dreq, mandatory, opt,
128                                                     *value, value + 1, len - 1);
129                         if (rc)
130                                 goto out_featneg_failed;
131                         break;
132                 case DCCPO_ACK_VECTOR_0:
133                 case DCCPO_ACK_VECTOR_1:
134                         if (dccp_packet_without_ack(skb))   /* RFC 4340, 11.4 */
135                                 break;
136                         if (dp->dccps_hc_rx_ackvec != NULL &&
137                             dccp_ackvec_parse(sk, skb, &ackno, opt, value, len))
138                                 goto out_invalid_option;
139                         break;
140                 case DCCPO_TIMESTAMP:
141                         if (len != 4)
142                                 goto out_invalid_option;
143                         /*
144                          * RFC 4340 13.1: "The precise time corresponding to
145                          * Timestamp Value zero is not specified". We use
146                          * zero to indicate absence of a meaningful timestamp.
147                          */
148                         opt_val = get_unaligned((__be32 *)value);
149                         if (unlikely(opt_val == 0)) {
150                                 DCCP_WARN("Timestamp with zero value\n");
151                                 break;
152                         }
153
154                         if (dreq != NULL) {
155                                 dreq->dreq_timestamp_echo = ntohl(opt_val);
156                                 dreq->dreq_timestamp_time = dccp_timestamp();
157                         } else {
158                                 opt_recv->dccpor_timestamp =
159                                         dp->dccps_timestamp_echo = ntohl(opt_val);
160                                 dp->dccps_timestamp_time = dccp_timestamp();
161                         }
162                         dccp_pr_debug("%s rx opt: TIMESTAMP=%u, ackno=%llu\n",
163                                       dccp_role(sk), ntohl(opt_val),
164                                       (unsigned long long)
165                                       DCCP_SKB_CB(skb)->dccpd_ack_seq);
166                         /* schedule an Ack in case this sender is quiescent */
167                         inet_csk_schedule_ack(sk);
168                         break;
169                 case DCCPO_TIMESTAMP_ECHO:
170                         if (len != 4 && len != 6 && len != 8)
171                                 goto out_invalid_option;
172
173                         opt_val = get_unaligned((__be32 *)value);
174                         opt_recv->dccpor_timestamp_echo = ntohl(opt_val);
175
176                         dccp_pr_debug("%s rx opt: TIMESTAMP_ECHO=%u, len=%d, "
177                                       "ackno=%llu", dccp_role(sk),
178                                       opt_recv->dccpor_timestamp_echo,
179                                       len + 2,
180                                       (unsigned long long)
181                                       DCCP_SKB_CB(skb)->dccpd_ack_seq);
182
183                         value += 4;
184
185                         if (len == 4) {         /* no elapsed time included */
186                                 dccp_pr_debug_cat("\n");
187                                 break;
188                         }
189
190                         if (len == 6) {         /* 2-byte elapsed time */
191                                 __be16 opt_val2 = get_unaligned((__be16 *)value);
192                                 elapsed_time = ntohs(opt_val2);
193                         } else {                /* 4-byte elapsed time */
194                                 opt_val = get_unaligned((__be32 *)value);
195                                 elapsed_time = ntohl(opt_val);
196                         }
197
198                         dccp_pr_debug_cat(", ELAPSED_TIME=%u\n", elapsed_time);
199
200                         /* Give precedence to the biggest ELAPSED_TIME */
201                         if (elapsed_time > opt_recv->dccpor_elapsed_time)
202                                 opt_recv->dccpor_elapsed_time = elapsed_time;
203                         break;
204                 case DCCPO_ELAPSED_TIME:
205                         if (dccp_packet_without_ack(skb))   /* RFC 4340, 13.2 */
206                                 break;
207
208                         if (len == 2) {
209                                 __be16 opt_val2 = get_unaligned((__be16 *)value);
210                                 elapsed_time = ntohs(opt_val2);
211                         } else if (len == 4) {
212                                 opt_val = get_unaligned((__be32 *)value);
213                                 elapsed_time = ntohl(opt_val);
214                         } else {
215                                 goto out_invalid_option;
216                         }
217
218                         if (elapsed_time > opt_recv->dccpor_elapsed_time)
219                                 opt_recv->dccpor_elapsed_time = elapsed_time;
220
221                         dccp_pr_debug("%s rx opt: ELAPSED_TIME=%d\n",
222                                       dccp_role(sk), elapsed_time);
223                         break;
224                 case DCCPO_MIN_RX_CCID_SPECIFIC ... DCCPO_MAX_RX_CCID_SPECIFIC:
225                         if (ccid_hc_rx_parse_options(dp->dccps_hc_rx_ccid, sk,
226                                                      pkt_type, opt, value, len))
227                                 goto out_invalid_option;
228                         break;
229                 case DCCPO_MIN_TX_CCID_SPECIFIC ... DCCPO_MAX_TX_CCID_SPECIFIC:
230                         if (ccid_hc_tx_parse_options(dp->dccps_hc_tx_ccid, sk,
231                                                      pkt_type, opt, value, len))
232                                 goto out_invalid_option;
233                         break;
234                 default:
235                         DCCP_CRIT("DCCP(%p): option %d(len=%d) not "
236                                   "implemented, ignoring", sk, opt, len);
237                         break;
238                 }
239 ignore_option:
240                 if (opt != DCCPO_MANDATORY)
241                         mandatory = 0;
242         }
243
244         /* mandatory was the last byte in option list -> reset connection */
245         if (mandatory)
246                 goto out_invalid_option;
247
248 out_nonsensical_length:
249         /* RFC 4340, 5.8: ignore option and all remaining option space */
250         return 0;
251
252 out_invalid_option:
253         DCCP_INC_STATS_BH(DCCP_MIB_INVALIDOPT);
254         rc = DCCP_RESET_CODE_OPTION_ERROR;
255 out_featneg_failed:
256         DCCP_WARN("DCCP(%p): Option %d (len=%d) error=%u\n", sk, opt, len, rc);
257         DCCP_SKB_CB(skb)->dccpd_reset_code = rc;
258         DCCP_SKB_CB(skb)->dccpd_reset_data[0] = opt;
259         DCCP_SKB_CB(skb)->dccpd_reset_data[1] = len > 0 ? value[0] : 0;
260         DCCP_SKB_CB(skb)->dccpd_reset_data[2] = len > 1 ? value[1] : 0;
261         return -1;
262 }
263
264 EXPORT_SYMBOL_GPL(dccp_parse_options);
265
266 void dccp_encode_value_var(const u64 value, u8 *to, const u8 len)
267 {
268         if (len >= DCCP_OPTVAL_MAXLEN)
269                 *to++ = (value & 0xFF0000000000ull) >> 40;
270         if (len > 4)
271                 *to++ = (value & 0xFF00000000ull) >> 32;
272         if (len > 3)
273                 *to++ = (value & 0xFF000000) >> 24;
274         if (len > 2)
275                 *to++ = (value & 0xFF0000) >> 16;
276         if (len > 1)
277                 *to++ = (value & 0xFF00) >> 8;
278         if (len > 0)
279                 *to++ = (value & 0xFF);
280 }
281
282 static inline u8 dccp_ndp_len(const u64 ndp)
283 {
284         if (likely(ndp <= 0xFF))
285                 return 1;
286         return likely(ndp <= USHRT_MAX) ? 2 : (ndp <= UINT_MAX ? 4 : 6);
287 }
288
289 int dccp_insert_option(struct sk_buff *skb, 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         u64 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 /* FIXME: This function is currently not used anywhere */
344 int dccp_insert_option_elapsed_time(struct sk_buff *skb, 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 static int dccp_insert_option_timestamp(struct sk_buff *skb)
376 {
377         __be32 now = htonl(dccp_timestamp());
378         /* yes this will overflow but that is the point as we want a
379          * 10 usec 32 bit timer which mean it wraps every 11.9 hours */
380
381         return dccp_insert_option(skb, DCCPO_TIMESTAMP, &now, sizeof(now));
382 }
383
384 static int dccp_insert_option_timestamp_echo(struct dccp_sock *dp,
385                                              struct dccp_request_sock *dreq,
386                                              struct sk_buff *skb)
387 {
388         __be32 tstamp_echo;
389         unsigned char *to;
390         u32 elapsed_time, elapsed_time_len, len;
391
392         if (dreq != NULL) {
393                 elapsed_time = dccp_timestamp() - dreq->dreq_timestamp_time;
394                 tstamp_echo  = htonl(dreq->dreq_timestamp_echo);
395                 dreq->dreq_timestamp_echo = 0;
396         } else {
397                 elapsed_time = dccp_timestamp() - dp->dccps_timestamp_time;
398                 tstamp_echo  = htonl(dp->dccps_timestamp_echo);
399                 dp->dccps_timestamp_echo = 0;
400         }
401
402         elapsed_time_len = dccp_elapsed_time_len(elapsed_time);
403         len = 6 + elapsed_time_len;
404
405         if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)
406                 return -1;
407
408         DCCP_SKB_CB(skb)->dccpd_opt_len += len;
409
410         to    = skb_push(skb, len);
411         *to++ = DCCPO_TIMESTAMP_ECHO;
412         *to++ = len;
413
414         memcpy(to, &tstamp_echo, 4);
415         to += 4;
416
417         if (elapsed_time_len == 2) {
418                 const __be16 var16 = htons((u16)elapsed_time);
419                 memcpy(to, &var16, 2);
420         } else if (elapsed_time_len == 4) {
421                 const __be32 var32 = htonl(elapsed_time);
422                 memcpy(to, &var32, 4);
423         }
424
425         return 0;
426 }
427
428 static int dccp_insert_option_ackvec(struct sock *sk, struct sk_buff *skb)
429 {
430         struct dccp_sock *dp = dccp_sk(sk);
431         struct dccp_ackvec *av = dp->dccps_hc_rx_ackvec;
432         /* Figure out how many options do we need to represent the ackvec */
433         const u8 nr_opts = DIV_ROUND_UP(av->av_vec_len, DCCP_SINGLE_OPT_MAXLEN);
434         u16 len = av->av_vec_len + 2 * nr_opts;
435         u8 i, nonce = 0;
436         const unsigned char *tail, *from;
437         unsigned char *to;
438
439         if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)
440                 return -1;
441
442         DCCP_SKB_CB(skb)->dccpd_opt_len += len;
443
444         to   = skb_push(skb, len);
445         len  = av->av_vec_len;
446         from = av->av_buf + av->av_buf_head;
447         tail = av->av_buf + DCCPAV_MAX_ACKVEC_LEN;
448
449         for (i = 0; i < nr_opts; ++i) {
450                 int copylen = len;
451
452                 if (len > DCCP_SINGLE_OPT_MAXLEN)
453                         copylen = DCCP_SINGLE_OPT_MAXLEN;
454
455                 /*
456                  * RFC 4340, 12.2: Encode the Nonce Echo for this Ack Vector via
457                  * its type; ack_nonce is the sum of all individual buf_nonce's.
458                  */
459                 nonce ^= av->av_buf_nonce[i];
460
461                 *to++ = DCCPO_ACK_VECTOR_0 + av->av_buf_nonce[i];
462                 *to++ = copylen + 2;
463
464                 /* Check if buf_head wraps */
465                 if (from + copylen > tail) {
466                         const u16 tailsize = tail - from;
467
468                         memcpy(to, from, tailsize);
469                         to      += tailsize;
470                         len     -= tailsize;
471                         copylen -= tailsize;
472                         from    = av->av_buf;
473                 }
474
475                 memcpy(to, from, copylen);
476                 from += copylen;
477                 to   += copylen;
478                 len  -= copylen;
479         }
480         /*
481          * Each sent Ack Vector is recorded in the list, as per A.2 of RFC 4340.
482          */
483         if (dccp_ackvec_update_records(av, DCCP_SKB_CB(skb)->dccpd_seq, nonce))
484                 return -ENOBUFS;
485         return 0;
486 }
487
488 /**
489  * dccp_insert_option_mandatory  -  Mandatory option (5.8.2)
490  * Note that since we are using skb_push, this function needs to be called
491  * _after_ inserting the option it is supposed to influence (stack order).
492  */
493 int dccp_insert_option_mandatory(struct sk_buff *skb)
494 {
495         if (DCCP_SKB_CB(skb)->dccpd_opt_len >= DCCP_MAX_OPT_LEN)
496                 return -1;
497
498         DCCP_SKB_CB(skb)->dccpd_opt_len++;
499         *skb_push(skb, 1) = DCCPO_MANDATORY;
500         return 0;
501 }
502
503 /**
504  * dccp_insert_fn_opt  -  Insert single Feature-Negotiation option into @skb
505  * @type: %DCCPO_CHANGE_L, %DCCPO_CHANGE_R, %DCCPO_CONFIRM_L, %DCCPO_CONFIRM_R
506  * @feat: one out of %dccp_feature_numbers
507  * @val: NN value or SP array (preferred element first) to copy
508  * @len: true length of @val in bytes (excluding first element repetition)
509  * @repeat_first: whether to copy the first element of @val twice
510  * The last argument is used to construct Confirm options, where the preferred
511  * value and the preference list appear separately (RFC 4340, 6.3.1). Preference
512  * lists are kept such that the preferred entry is always first, so we only need
513  * to copy twice, and avoid the overhead of cloning into a bigger array.
514  */
515 int dccp_insert_fn_opt(struct sk_buff *skb, u8 type, u8 feat,
516                        u8 *val, u8 len, bool repeat_first)
517 {
518         u8 tot_len, *to;
519
520         /* take the `Feature' field and possible repetition into account */
521         if (len > (DCCP_SINGLE_OPT_MAXLEN - 2)) {
522                 DCCP_WARN("length %u for feature %u too large\n", len, feat);
523                 return -1;
524         }
525
526         if (unlikely(val == NULL || len == 0))
527                 len = repeat_first = 0;
528         tot_len = 3 + repeat_first + len;
529
530         if (DCCP_SKB_CB(skb)->dccpd_opt_len + tot_len > DCCP_MAX_OPT_LEN) {
531                 DCCP_WARN("packet too small for feature %d option!\n", feat);
532                 return -1;
533         }
534         DCCP_SKB_CB(skb)->dccpd_opt_len += tot_len;
535
536         to    = skb_push(skb, tot_len);
537         *to++ = type;
538         *to++ = tot_len;
539         *to++ = feat;
540
541         if (repeat_first)
542                 *to++ = *val;
543         if (len)
544                 memcpy(to, val, len);
545         return 0;
546 }
547
548 /* The length of all options needs to be a multiple of 4 (5.8) */
549 static void dccp_insert_option_padding(struct sk_buff *skb)
550 {
551         int padding = DCCP_SKB_CB(skb)->dccpd_opt_len % 4;
552
553         if (padding != 0) {
554                 padding = 4 - padding;
555                 memset(skb_push(skb, padding), 0, padding);
556                 DCCP_SKB_CB(skb)->dccpd_opt_len += padding;
557         }
558 }
559
560 int dccp_insert_options(struct sock *sk, struct sk_buff *skb)
561 {
562         struct dccp_sock *dp = dccp_sk(sk);
563
564         DCCP_SKB_CB(skb)->dccpd_opt_len = 0;
565
566         if (dp->dccps_send_ndp_count && dccp_insert_option_ndp(sk, skb))
567                 return -1;
568
569         if (DCCP_SKB_CB(skb)->dccpd_type != DCCP_PKT_DATA) {
570
571                 /* Feature Negotiation */
572                 if (dccp_feat_insert_opts(dp, NULL, skb))
573                         return -1;
574
575                 if (DCCP_SKB_CB(skb)->dccpd_type == DCCP_PKT_REQUEST) {
576                         /*
577                          * Obtain RTT sample from Request/Response exchange.
578                          * This is currently used for TFRC initialisation.
579                          */
580                         if (dccp_insert_option_timestamp(skb))
581                                 return -1;
582
583                 } else if (dp->dccps_hc_rx_ackvec != NULL &&
584                            dccp_ackvec_pending(dp->dccps_hc_rx_ackvec) &&
585                            dccp_insert_option_ackvec(sk, skb)) {
586                                 return -1;
587                 }
588         }
589
590         if (dp->dccps_hc_rx_insert_options) {
591                 if (ccid_hc_rx_insert_options(dp->dccps_hc_rx_ccid, sk, skb))
592                         return -1;
593                 dp->dccps_hc_rx_insert_options = 0;
594         }
595
596         if (dp->dccps_timestamp_echo != 0 &&
597             dccp_insert_option_timestamp_echo(dp, NULL, skb))
598                 return -1;
599
600         dccp_insert_option_padding(skb);
601         return 0;
602 }
603
604 int dccp_insert_options_rsk(struct dccp_request_sock *dreq, struct sk_buff *skb)
605 {
606         DCCP_SKB_CB(skb)->dccpd_opt_len = 0;
607
608         if (dccp_feat_insert_opts(NULL, dreq, skb))
609                 return -1;
610
611         /* Obtain RTT sample from Response/Ack exchange (used by TFRC). */
612         if (dccp_insert_option_timestamp(skb))
613                 return -1;
614
615         if (dreq->dreq_timestamp_echo != 0 &&
616             dccp_insert_option_timestamp_echo(NULL, dreq, skb))
617                 return -1;
618
619         dccp_insert_option_padding(skb);
620         return 0;
621 }