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Merge branch 'for-linus' of git://git390.marist.edu/pub/scm/linux-2.6
[linux-2.6/cjktty.git] / net / dccp / options.c
blobf06ffcfc8d712421040c71a56513b90dcfca96c7
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 unsigned char *options = (unsigned char *)dh + dccp_hdr_len(skb);
58 unsigned char *opt_ptr = options;
59 const unsigned char *opt_end = (unsigned char *)dh +
60 (dh->dccph_doff * 4);
61 struct dccp_options_received *opt_recv = &dp->dccps_options_received;
62 unsigned char opt, len;
63 unsigned char *uninitialized_var(value);
64 u32 elapsed_time;
65 __be32 opt_val;
66 int rc;
67 int mandatory = 0;
68
69 memset(opt_recv, 0, sizeof(*opt_recv));
70
71 opt = len = 0;
72 while (opt_ptr != opt_end) {
73 opt = *opt_ptr++;
74 len = 0;
75 value = NULL;
76
77 /* Check if this isn't a single byte option */
78 if (opt > DCCPO_MAX_RESERVED) {
79 if (opt_ptr == opt_end)
80 goto out_nonsensical_length;
81
82 len = *opt_ptr++;
83 if (len < 2)
84 goto out_nonsensical_length;
85 /*
86 * Remove the type and len fields, leaving
87 * just the value size
88 */
89 len -= 2;
90 value = opt_ptr;
91 opt_ptr += len;
92
93 if (opt_ptr > opt_end)
94 goto out_nonsensical_length;
95 }
96
97 /*
98 * CCID-specific options are ignored during connection setup, as
99 * negotiation may still be in progress (see RFC 4340, 10.3).
100 * The same applies to Ack Vectors, as these depend on the CCID.
101 */
102 if (dreq != NULL && (opt >= DCCPO_MIN_RX_CCID_SPECIFIC ||
103 opt == DCCPO_ACK_VECTOR_0 || opt == DCCPO_ACK_VECTOR_1))
104 goto ignore_option;
105
106 switch (opt) {
107 case DCCPO_PADDING:
108 break;
109 case DCCPO_MANDATORY:
110 if (mandatory)
111 goto out_invalid_option;
112 if (pkt_type != DCCP_PKT_DATA)
113 mandatory = 1;
114 break;
115 case DCCPO_NDP_COUNT:
116 if (len > 6)
117 goto out_invalid_option;
118
119 opt_recv->dccpor_ndp = dccp_decode_value_var(value, len);
120 dccp_pr_debug("%s opt: NDP count=%llu\n", dccp_role(sk),
121 (unsigned long long)opt_recv->dccpor_ndp);
122 break;
123 case DCCPO_CHANGE_L ... DCCPO_CONFIRM_R:
124 if (pkt_type == DCCP_PKT_DATA) /* RFC 4340, 6 */
125 break;
126 rc = dccp_feat_parse_options(sk, dreq, mandatory, opt,
127 *value, value + 1, len - 1);
128 if (rc)
129 goto out_featneg_failed;
130 break;
131 case DCCPO_TIMESTAMP:
132 if (len != 4)
133 goto out_invalid_option;
134 /*
135 * RFC 4340 13.1: "The precise time corresponding to
136 * Timestamp Value zero is not specified". We use
137 * zero to indicate absence of a meaningful timestamp.
138 */
139 opt_val = get_unaligned((__be32 *)value);
140 if (unlikely(opt_val == 0)) {
141 DCCP_WARN("Timestamp with zero value\n");
142 break;
143 }
144
145 if (dreq != NULL) {
146 dreq->dreq_timestamp_echo = ntohl(opt_val);
147 dreq->dreq_timestamp_time = dccp_timestamp();
148 } else {
149 opt_recv->dccpor_timestamp =
150 dp->dccps_timestamp_echo = ntohl(opt_val);
151 dp->dccps_timestamp_time = dccp_timestamp();
152 }
153 dccp_pr_debug("%s rx opt: TIMESTAMP=%u, ackno=%llu\n",
154 dccp_role(sk), ntohl(opt_val),
155 (unsigned long long)
156 DCCP_SKB_CB(skb)->dccpd_ack_seq);
157 /* schedule an Ack in case this sender is quiescent */
158 inet_csk_schedule_ack(sk);
159 break;
160 case DCCPO_TIMESTAMP_ECHO:
161 if (len != 4 && len != 6 && len != 8)
162 goto out_invalid_option;
163
164 opt_val = get_unaligned((__be32 *)value);
165 opt_recv->dccpor_timestamp_echo = ntohl(opt_val);
166
167 dccp_pr_debug("%s rx opt: TIMESTAMP_ECHO=%u, len=%d, "
168 "ackno=%llu", dccp_role(sk),
169 opt_recv->dccpor_timestamp_echo,
170 len + 2,
171 (unsigned long long)
172 DCCP_SKB_CB(skb)->dccpd_ack_seq);
173
174 value += 4;
175
176 if (len == 4) { /* no elapsed time included */
177 dccp_pr_debug_cat("\n");
178 break;
179 }
180
181 if (len == 6) { /* 2-byte elapsed time */
182 __be16 opt_val2 = get_unaligned((__be16 *)value);
183 elapsed_time = ntohs(opt_val2);
184 } else { /* 4-byte elapsed time */
185 opt_val = get_unaligned((__be32 *)value);
186 elapsed_time = ntohl(opt_val);
187 }
188
189 dccp_pr_debug_cat(", ELAPSED_TIME=%u\n", elapsed_time);
190
191 /* Give precedence to the biggest ELAPSED_TIME */
192 if (elapsed_time > opt_recv->dccpor_elapsed_time)
193 opt_recv->dccpor_elapsed_time = elapsed_time;
194 break;
195 case DCCPO_ELAPSED_TIME:
196 if (dccp_packet_without_ack(skb)) /* RFC 4340, 13.2 */
197 break;
198
199 if (len == 2) {
200 __be16 opt_val2 = get_unaligned((__be16 *)value);
201 elapsed_time = ntohs(opt_val2);
202 } else if (len == 4) {
203 opt_val = get_unaligned((__be32 *)value);
204 elapsed_time = ntohl(opt_val);
205 } else {
206 goto out_invalid_option;
207 }
208
209 if (elapsed_time > opt_recv->dccpor_elapsed_time)
210 opt_recv->dccpor_elapsed_time = elapsed_time;
211
212 dccp_pr_debug("%s rx opt: ELAPSED_TIME=%d\n",
213 dccp_role(sk), elapsed_time);
214 break;
215 case DCCPO_MIN_RX_CCID_SPECIFIC ... DCCPO_MAX_RX_CCID_SPECIFIC:
216 if (ccid_hc_rx_parse_options(dp->dccps_hc_rx_ccid, sk,
217 pkt_type, opt, value, len))
218 goto out_invalid_option;
219 break;
220 case DCCPO_ACK_VECTOR_0:
221 case DCCPO_ACK_VECTOR_1:
222 if (dccp_packet_without_ack(skb)) /* RFC 4340, 11.4 */
223 break;
224 /*
225 * Ack vectors are processed by the TX CCID if it is
226 * interested. The RX CCID need not parse Ack Vectors,
227 * since it is only interested in clearing old state.
228 * Fall through.
229 */
230 case DCCPO_MIN_TX_CCID_SPECIFIC ... DCCPO_MAX_TX_CCID_SPECIFIC:
231 if (ccid_hc_tx_parse_options(dp->dccps_hc_tx_ccid, sk,
232 pkt_type, opt, value, len))
233 goto out_invalid_option;
234 break;
235 default:
236 DCCP_CRIT("DCCP(%p): option %d(len=%d) not "
237 "implemented, ignoring", sk, opt, len);
238 break;
239 }
240 ignore_option:
241 if (opt != DCCPO_MANDATORY)
242 mandatory = 0;
243 }
244
245 /* mandatory was the last byte in option list -> reset connection */
246 if (mandatory)
247 goto out_invalid_option;
248
249 out_nonsensical_length:
250 /* RFC 4340, 5.8: ignore option and all remaining option space */
251 return 0;
252
253 out_invalid_option:
254 DCCP_INC_STATS_BH(DCCP_MIB_INVALIDOPT);
255 rc = DCCP_RESET_CODE_OPTION_ERROR;
256 out_featneg_failed:
257 DCCP_WARN("DCCP(%p): Option %d (len=%d) error=%u\n", sk, opt, len, rc);
258 DCCP_SKB_CB(skb)->dccpd_reset_code = rc;
259 DCCP_SKB_CB(skb)->dccpd_reset_data[0] = opt;
260 DCCP_SKB_CB(skb)->dccpd_reset_data[1] = len > 0 ? value[0] : 0;
261 DCCP_SKB_CB(skb)->dccpd_reset_data[2] = len > 1 ? value[1] : 0;
262 return -1;
263 }
264
265 EXPORT_SYMBOL_GPL(dccp_parse_options);
266
267 void dccp_encode_value_var(const u64 value, u8 *to, const u8 len)
268 {
269 if (len >= DCCP_OPTVAL_MAXLEN)
270 *to++ = (value & 0xFF0000000000ull) >> 40;
271 if (len > 4)
272 *to++ = (value & 0xFF00000000ull) >> 32;
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 u8 dccp_ndp_len(const u64 ndp)
284 {
285 if (likely(ndp <= 0xFF))
286 return 1;
287 return likely(ndp <= USHRT_MAX) ? 2 : (ndp <= UINT_MAX ? 4 : 6);
288 }
289
290 int dccp_insert_option(struct sk_buff *skb, const unsigned char option,
291 const void *value, const unsigned char len)
292 {
293 unsigned char *to;
294
295 if (DCCP_SKB_CB(skb)->dccpd_opt_len + len + 2 > DCCP_MAX_OPT_LEN)
296 return -1;
297
298 DCCP_SKB_CB(skb)->dccpd_opt_len += len + 2;
299
300 to = skb_push(skb, len + 2);
301 *to++ = option;
302 *to++ = len + 2;
303
304 memcpy(to, value, len);
305 return 0;
306 }
307
308 EXPORT_SYMBOL_GPL(dccp_insert_option);
309
310 static int dccp_insert_option_ndp(struct sock *sk, struct sk_buff *skb)
311 {
312 struct dccp_sock *dp = dccp_sk(sk);
313 u64 ndp = dp->dccps_ndp_count;
314
315 if (dccp_non_data_packet(skb))
316 ++dp->dccps_ndp_count;
317 else
318 dp->dccps_ndp_count = 0;
319
320 if (ndp > 0) {
321 unsigned char *ptr;
322 const int ndp_len = dccp_ndp_len(ndp);
323 const int len = ndp_len + 2;
324
325 if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)
326 return -1;
327
328 DCCP_SKB_CB(skb)->dccpd_opt_len += len;
329
330 ptr = skb_push(skb, len);
331 *ptr++ = DCCPO_NDP_COUNT;
332 *ptr++ = len;
333 dccp_encode_value_var(ndp, ptr, ndp_len);
334 }
335
336 return 0;
337 }
338
339 static inline int dccp_elapsed_time_len(const u32 elapsed_time)
340 {
341 return elapsed_time == 0 ? 0 : elapsed_time <= 0xFFFF ? 2 : 4;
342 }
343
344 /* FIXME: This function is currently not used anywhere */
345 int dccp_insert_option_elapsed_time(struct sk_buff *skb, u32 elapsed_time)
346 {
347 const int elapsed_time_len = dccp_elapsed_time_len(elapsed_time);
348 const int len = 2 + elapsed_time_len;
349 unsigned char *to;
350
351 if (elapsed_time_len == 0)
352 return 0;
353
354 if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)
355 return -1;
356
357 DCCP_SKB_CB(skb)->dccpd_opt_len += len;
358
359 to = skb_push(skb, len);
360 *to++ = DCCPO_ELAPSED_TIME;
361 *to++ = len;
362
363 if (elapsed_time_len == 2) {
364 const __be16 var16 = htons((u16)elapsed_time);
365 memcpy(to, &var16, 2);
366 } else {
367 const __be32 var32 = htonl(elapsed_time);
368 memcpy(to, &var32, 4);
369 }
370
371 return 0;
372 }
373
374 EXPORT_SYMBOL_GPL(dccp_insert_option_elapsed_time);
375
376 static int dccp_insert_option_timestamp(struct sk_buff *skb)
377 {
378 __be32 now = htonl(dccp_timestamp());
379 /* yes this will overflow but that is the point as we want a
380 * 10 usec 32 bit timer which mean it wraps every 11.9 hours */
381
382 return dccp_insert_option(skb, DCCPO_TIMESTAMP, &now, sizeof(now));
383 }
384
385 static int dccp_insert_option_timestamp_echo(struct dccp_sock *dp,
386 struct dccp_request_sock *dreq,
387 struct sk_buff *skb)
388 {
389 __be32 tstamp_echo;
390 unsigned char *to;
391 u32 elapsed_time, elapsed_time_len, len;
392
393 if (dreq != NULL) {
394 elapsed_time = dccp_timestamp() - dreq->dreq_timestamp_time;
395 tstamp_echo = htonl(dreq->dreq_timestamp_echo);
396 dreq->dreq_timestamp_echo = 0;
397 } else {
398 elapsed_time = dccp_timestamp() - dp->dccps_timestamp_time;
399 tstamp_echo = htonl(dp->dccps_timestamp_echo);
400 dp->dccps_timestamp_echo = 0;
401 }
402
403 elapsed_time_len = dccp_elapsed_time_len(elapsed_time);
404 len = 6 + elapsed_time_len;
405
406 if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)
407 return -1;
408
409 DCCP_SKB_CB(skb)->dccpd_opt_len += len;
410
411 to = skb_push(skb, len);
412 *to++ = DCCPO_TIMESTAMP_ECHO;
413 *to++ = len;
414
415 memcpy(to, &tstamp_echo, 4);
416 to += 4;
417
418 if (elapsed_time_len == 2) {
419 const __be16 var16 = htons((u16)elapsed_time);
420 memcpy(to, &var16, 2);
421 } else if (elapsed_time_len == 4) {
422 const __be32 var32 = htonl(elapsed_time);
423 memcpy(to, &var32, 4);
424 }
425
426 return 0;
427 }
428
429 static int dccp_insert_option_ackvec(struct sock *sk, struct sk_buff *skb)
430 {
431 struct dccp_sock *dp = dccp_sk(sk);
432 struct dccp_ackvec *av = dp->dccps_hc_rx_ackvec;
433 struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
434 const u16 buflen = dccp_ackvec_buflen(av);
435 /* Figure out how many options do we need to represent the ackvec */
436 const u8 nr_opts = DIV_ROUND_UP(buflen, DCCP_SINGLE_OPT_MAXLEN);
437 u16 len = buflen + 2 * nr_opts;
438 u8 i, nonce = 0;
439 const unsigned char *tail, *from;
440 unsigned char *to;
441
442 if (dcb->dccpd_opt_len + len > DCCP_MAX_OPT_LEN) {
443 DCCP_WARN("Lacking space for %u bytes on %s packet\n", len,
444 dccp_packet_name(dcb->dccpd_type));
445 return -1;
446 }
447 /*
448 * Since Ack Vectors are variable-length, we can not always predict
449 * their size. To catch exception cases where the space is running out
450 * on the skb, a separate Sync is scheduled to carry the Ack Vector.
451 */
452 if (len > DCCPAV_MIN_OPTLEN &&
453 len + dcb->dccpd_opt_len + skb->len > dp->dccps_mss_cache) {
454 DCCP_WARN("No space left for Ack Vector (%u) on skb (%u+%u), "
455 "MPS=%u ==> reduce payload size?\n", len, skb->len,
456 dcb->dccpd_opt_len, dp->dccps_mss_cache);
457 dp->dccps_sync_scheduled = 1;
458 return 0;
459 }
460 dcb->dccpd_opt_len += len;
461
462 to = skb_push(skb, len);
463 len = buflen;
464 from = av->av_buf + av->av_buf_head;
465 tail = av->av_buf + DCCPAV_MAX_ACKVEC_LEN;
466
467 for (i = 0; i < nr_opts; ++i) {
468 int copylen = len;
469
470 if (len > DCCP_SINGLE_OPT_MAXLEN)
471 copylen = DCCP_SINGLE_OPT_MAXLEN;
472
473 /*
474 * RFC 4340, 12.2: Encode the Nonce Echo for this Ack Vector via
475 * its type; ack_nonce is the sum of all individual buf_nonce's.
476 */
477 nonce ^= av->av_buf_nonce[i];
478
479 *to++ = DCCPO_ACK_VECTOR_0 + av->av_buf_nonce[i];
480 *to++ = copylen + 2;
481
482 /* Check if buf_head wraps */
483 if (from + copylen > tail) {
484 const u16 tailsize = tail - from;
485
486 memcpy(to, from, tailsize);
487 to += tailsize;
488 len -= tailsize;
489 copylen -= tailsize;
490 from = av->av_buf;
491 }
492
493 memcpy(to, from, copylen);
494 from += copylen;
495 to += copylen;
496 len -= copylen;
497 }
498 /*
499 * Each sent Ack Vector is recorded in the list, as per A.2 of RFC 4340.
500 */
501 if (dccp_ackvec_update_records(av, dcb->dccpd_seq, nonce))
502 return -ENOBUFS;
503 return 0;
504 }
505
506 /**
507 * dccp_insert_option_mandatory - Mandatory option (5.8.2)
508 * Note that since we are using skb_push, this function needs to be called
509 * _after_ inserting the option it is supposed to influence (stack order).
510 */
511 int dccp_insert_option_mandatory(struct sk_buff *skb)
512 {
513 if (DCCP_SKB_CB(skb)->dccpd_opt_len >= DCCP_MAX_OPT_LEN)
514 return -1;
515
516 DCCP_SKB_CB(skb)->dccpd_opt_len++;
517 *skb_push(skb, 1) = DCCPO_MANDATORY;
518 return 0;
519 }
520
521 /**
522 * dccp_insert_fn_opt - Insert single Feature-Negotiation option into @skb
523 * @type: %DCCPO_CHANGE_L, %DCCPO_CHANGE_R, %DCCPO_CONFIRM_L, %DCCPO_CONFIRM_R
524 * @feat: one out of %dccp_feature_numbers
525 * @val: NN value or SP array (preferred element first) to copy
526 * @len: true length of @val in bytes (excluding first element repetition)
527 * @repeat_first: whether to copy the first element of @val twice
528 * The last argument is used to construct Confirm options, where the preferred
529 * value and the preference list appear separately (RFC 4340, 6.3.1). Preference
530 * lists are kept such that the preferred entry is always first, so we only need
531 * to copy twice, and avoid the overhead of cloning into a bigger array.
532 */
533 int dccp_insert_fn_opt(struct sk_buff *skb, u8 type, u8 feat,
534 u8 *val, u8 len, bool repeat_first)
535 {
536 u8 tot_len, *to;
537
538 /* take the `Feature' field and possible repetition into account */
539 if (len > (DCCP_SINGLE_OPT_MAXLEN - 2)) {
540 DCCP_WARN("length %u for feature %u too large\n", len, feat);
541 return -1;
542 }
543
544 if (unlikely(val == NULL || len == 0))
545 len = repeat_first = 0;
546 tot_len = 3 + repeat_first + len;
547
548 if (DCCP_SKB_CB(skb)->dccpd_opt_len + tot_len > DCCP_MAX_OPT_LEN) {
549 DCCP_WARN("packet too small for feature %d option!\n", feat);
550 return -1;
551 }
552 DCCP_SKB_CB(skb)->dccpd_opt_len += tot_len;
553
554 to = skb_push(skb, tot_len);
555 *to++ = type;
556 *to++ = tot_len;
557 *to++ = feat;
558
559 if (repeat_first)
560 *to++ = *val;
561 if (len)
562 memcpy(to, val, len);
563 return 0;
564 }
565
566 /* The length of all options needs to be a multiple of 4 (5.8) */
567 static void dccp_insert_option_padding(struct sk_buff *skb)
568 {
569 int padding = DCCP_SKB_CB(skb)->dccpd_opt_len % 4;
570
571 if (padding != 0) {
572 padding = 4 - padding;
573 memset(skb_push(skb, padding), 0, padding);
574 DCCP_SKB_CB(skb)->dccpd_opt_len += padding;
575 }
576 }
577
578 int dccp_insert_options(struct sock *sk, struct sk_buff *skb)
579 {
580 struct dccp_sock *dp = dccp_sk(sk);
581
582 DCCP_SKB_CB(skb)->dccpd_opt_len = 0;
583
584 if (dp->dccps_send_ndp_count && dccp_insert_option_ndp(sk, skb))
585 return -1;
586
587 if (DCCP_SKB_CB(skb)->dccpd_type != DCCP_PKT_DATA) {
588
589 /* Feature Negotiation */
590 if (dccp_feat_insert_opts(dp, NULL, skb))
591 return -1;
592
593 if (DCCP_SKB_CB(skb)->dccpd_type == DCCP_PKT_REQUEST) {
594 /*
595 * Obtain RTT sample from Request/Response exchange.
596 * This is currently used for TFRC initialisation.
597 */
598 if (dccp_insert_option_timestamp(skb))
599 return -1;
600
601 } else if (dccp_ackvec_pending(sk) &&
602 dccp_insert_option_ackvec(sk, skb)) {
603 return -1;
604 }
605 }
606
607 if (dp->dccps_hc_rx_insert_options) {
608 if (ccid_hc_rx_insert_options(dp->dccps_hc_rx_ccid, sk, skb))
609 return -1;
610 dp->dccps_hc_rx_insert_options = 0;
611 }
612
613 if (dp->dccps_timestamp_echo != 0 &&
614 dccp_insert_option_timestamp_echo(dp, NULL, skb))
615 return -1;
616
617 dccp_insert_option_padding(skb);
618 return 0;
619 }
620
621 int dccp_insert_options_rsk(struct dccp_request_sock *dreq, struct sk_buff *skb)
622 {
623 DCCP_SKB_CB(skb)->dccpd_opt_len = 0;
624
625 if (dccp_feat_insert_opts(NULL, dreq, skb))
626 return -1;
627
628 /* Obtain RTT sample from Response/Ack exchange (used by TFRC). */
629 if (dccp_insert_option_timestamp(skb))
630 return -1;
631
632 if (dreq->dreq_timestamp_echo != 0 &&
633 dccp_insert_option_timestamp_echo(NULL, dreq, skb))
634 return -1;
635
636 dccp_insert_option_padding(skb);
637 return 0;
638 }
CJK support for tty framebuffer vt