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>
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.
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>
26 u64 dccp_decode_value_var(const u8 *bf, const u8 len)
30 if (len >= DCCP_OPTVAL_MAXLEN)
31 value += ((u64)*bf++) << 40;
33 value += ((u64)*bf++) << 32;
35 value += ((u64)*bf++) << 24;
37 value += ((u64)*bf++) << 16;
39 value += ((u64)*bf++) << 8;
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
51 int dccp_parse_options(struct sock *sk, struct dccp_request_sock *dreq,
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 +
61 struct dccp_options_received *opt_recv = &dp->dccps_options_received;
62 unsigned char opt, len;
63 unsigned char *uninitialized_var(value);
69 memset(opt_recv, 0, sizeof(*opt_recv));
72 while (opt_ptr != opt_end) {
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;
84 goto out_nonsensical_length;
86 * Remove the type and len fields, leaving
93 if (opt_ptr > opt_end)
94 goto out_nonsensical_length;
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.
102 if (dreq != NULL && (opt >= DCCPO_MIN_RX_CCID_SPECIFIC ||
103 opt == DCCPO_ACK_VECTOR_0 || opt == DCCPO_ACK_VECTOR_1))
109 case DCCPO_MANDATORY:
111 goto out_invalid_option;
112 if (pkt_type != DCCP_PKT_DATA)
115 case DCCPO_NDP_COUNT:
117 goto out_invalid_option;
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);
123 case DCCPO_CHANGE_L ... DCCPO_CONFIRM_R:
124 if (pkt_type == DCCP_PKT_DATA) /* RFC 4340, 6 */
126 rc = dccp_feat_parse_options(sk, dreq, mandatory, opt,
127 *value, value + 1, len - 1);
129 goto out_featneg_failed;
131 case DCCPO_ACK_VECTOR_0:
132 case DCCPO_ACK_VECTOR_1:
133 if (dccp_packet_without_ack(skb)) /* RFC 4340, 11.4 */
135 dccp_pr_debug("%s Ack Vector (len=%u)\n", dccp_role(sk),
138 case DCCPO_TIMESTAMP:
140 goto out_invalid_option;
142 * RFC 4340 13.1: "The precise time corresponding to
143 * Timestamp Value zero is not specified". We use
144 * zero to indicate absence of a meaningful timestamp.
146 opt_val = get_unaligned((__be32 *)value);
147 if (unlikely(opt_val == 0)) {
148 DCCP_WARN("Timestamp with zero value\n");
153 dreq->dreq_timestamp_echo = ntohl(opt_val);
154 dreq->dreq_timestamp_time = dccp_timestamp();
156 opt_recv->dccpor_timestamp =
157 dp->dccps_timestamp_echo = ntohl(opt_val);
158 dp->dccps_timestamp_time = dccp_timestamp();
160 dccp_pr_debug("%s rx opt: TIMESTAMP=%u, ackno=%llu\n",
161 dccp_role(sk), ntohl(opt_val),
163 DCCP_SKB_CB(skb)->dccpd_ack_seq);
164 /* schedule an Ack in case this sender is quiescent */
165 inet_csk_schedule_ack(sk);
167 case DCCPO_TIMESTAMP_ECHO:
168 if (len != 4 && len != 6 && len != 8)
169 goto out_invalid_option;
171 opt_val = get_unaligned((__be32 *)value);
172 opt_recv->dccpor_timestamp_echo = ntohl(opt_val);
174 dccp_pr_debug("%s rx opt: TIMESTAMP_ECHO=%u, len=%d, "
175 "ackno=%llu", dccp_role(sk),
176 opt_recv->dccpor_timestamp_echo,
179 DCCP_SKB_CB(skb)->dccpd_ack_seq);
183 if (len == 4) { /* no elapsed time included */
184 dccp_pr_debug_cat("\n");
188 if (len == 6) { /* 2-byte elapsed time */
189 __be16 opt_val2 = get_unaligned((__be16 *)value);
190 elapsed_time = ntohs(opt_val2);
191 } else { /* 4-byte elapsed time */
192 opt_val = get_unaligned((__be32 *)value);
193 elapsed_time = ntohl(opt_val);
196 dccp_pr_debug_cat(", ELAPSED_TIME=%u\n", elapsed_time);
198 /* Give precedence to the biggest ELAPSED_TIME */
199 if (elapsed_time > opt_recv->dccpor_elapsed_time)
200 opt_recv->dccpor_elapsed_time = elapsed_time;
202 case DCCPO_ELAPSED_TIME:
203 if (dccp_packet_without_ack(skb)) /* RFC 4340, 13.2 */
207 __be16 opt_val2 = get_unaligned((__be16 *)value);
208 elapsed_time = ntohs(opt_val2);
209 } else if (len == 4) {
210 opt_val = get_unaligned((__be32 *)value);
211 elapsed_time = ntohl(opt_val);
213 goto out_invalid_option;
216 if (elapsed_time > opt_recv->dccpor_elapsed_time)
217 opt_recv->dccpor_elapsed_time = elapsed_time;
219 dccp_pr_debug("%s rx opt: ELAPSED_TIME=%d\n",
220 dccp_role(sk), elapsed_time);
222 case DCCPO_MIN_RX_CCID_SPECIFIC ... DCCPO_MAX_RX_CCID_SPECIFIC:
223 if (ccid_hc_rx_parse_options(dp->dccps_hc_rx_ccid, sk,
224 pkt_type, opt, value, len))
225 goto out_invalid_option;
227 case DCCPO_MIN_TX_CCID_SPECIFIC ... DCCPO_MAX_TX_CCID_SPECIFIC:
228 if (ccid_hc_tx_parse_options(dp->dccps_hc_tx_ccid, sk,
229 pkt_type, opt, value, len))
230 goto out_invalid_option;
233 DCCP_CRIT("DCCP(%p): option %d(len=%d) not "
234 "implemented, ignoring", sk, opt, len);
238 if (opt != DCCPO_MANDATORY)
242 /* mandatory was the last byte in option list -> reset connection */
244 goto out_invalid_option;
246 out_nonsensical_length:
247 /* RFC 4340, 5.8: ignore option and all remaining option space */
251 DCCP_INC_STATS_BH(DCCP_MIB_INVALIDOPT);
252 rc = DCCP_RESET_CODE_OPTION_ERROR;
254 DCCP_WARN("DCCP(%p): Option %d (len=%d) error=%u\n", sk, opt, len, rc);
255 DCCP_SKB_CB(skb)->dccpd_reset_code = rc;
256 DCCP_SKB_CB(skb)->dccpd_reset_data[0] = opt;
257 DCCP_SKB_CB(skb)->dccpd_reset_data[1] = len > 0 ? value[0] : 0;
258 DCCP_SKB_CB(skb)->dccpd_reset_data[2] = len > 1 ? value[1] : 0;
262 EXPORT_SYMBOL_GPL(dccp_parse_options);
264 void dccp_encode_value_var(const u64 value, u8 *to, const u8 len)
266 if (len >= DCCP_OPTVAL_MAXLEN)
267 *to++ = (value & 0xFF0000000000ull) >> 40;
269 *to++ = (value & 0xFF00000000ull) >> 32;
271 *to++ = (value & 0xFF000000) >> 24;
273 *to++ = (value & 0xFF0000) >> 16;
275 *to++ = (value & 0xFF00) >> 8;
277 *to++ = (value & 0xFF);
280 static inline u8 dccp_ndp_len(const u64 ndp)
282 if (likely(ndp <= 0xFF))
284 return likely(ndp <= USHRT_MAX) ? 2 : (ndp <= UINT_MAX ? 4 : 6);
287 int dccp_insert_option(struct sk_buff *skb, const unsigned char option,
288 const void *value, const unsigned char len)
292 if (DCCP_SKB_CB(skb)->dccpd_opt_len + len + 2 > DCCP_MAX_OPT_LEN)
295 DCCP_SKB_CB(skb)->dccpd_opt_len += len + 2;
297 to = skb_push(skb, len + 2);
301 memcpy(to, value, len);
305 EXPORT_SYMBOL_GPL(dccp_insert_option);
307 static int dccp_insert_option_ndp(struct sock *sk, struct sk_buff *skb)
309 struct dccp_sock *dp = dccp_sk(sk);
310 u64 ndp = dp->dccps_ndp_count;
312 if (dccp_non_data_packet(skb))
313 ++dp->dccps_ndp_count;
315 dp->dccps_ndp_count = 0;
319 const int ndp_len = dccp_ndp_len(ndp);
320 const int len = ndp_len + 2;
322 if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)
325 DCCP_SKB_CB(skb)->dccpd_opt_len += len;
327 ptr = skb_push(skb, len);
328 *ptr++ = DCCPO_NDP_COUNT;
330 dccp_encode_value_var(ndp, ptr, ndp_len);
336 static inline int dccp_elapsed_time_len(const u32 elapsed_time)
338 return elapsed_time == 0 ? 0 : elapsed_time <= 0xFFFF ? 2 : 4;
341 /* FIXME: This function is currently not used anywhere */
342 int dccp_insert_option_elapsed_time(struct sk_buff *skb, u32 elapsed_time)
344 const int elapsed_time_len = dccp_elapsed_time_len(elapsed_time);
345 const int len = 2 + elapsed_time_len;
348 if (elapsed_time_len == 0)
351 if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)
354 DCCP_SKB_CB(skb)->dccpd_opt_len += len;
356 to = skb_push(skb, len);
357 *to++ = DCCPO_ELAPSED_TIME;
360 if (elapsed_time_len == 2) {
361 const __be16 var16 = htons((u16)elapsed_time);
362 memcpy(to, &var16, 2);
364 const __be32 var32 = htonl(elapsed_time);
365 memcpy(to, &var32, 4);
371 EXPORT_SYMBOL_GPL(dccp_insert_option_elapsed_time);
373 static int dccp_insert_option_timestamp(struct sk_buff *skb)
375 __be32 now = htonl(dccp_timestamp());
376 /* yes this will overflow but that is the point as we want a
377 * 10 usec 32 bit timer which mean it wraps every 11.9 hours */
379 return dccp_insert_option(skb, DCCPO_TIMESTAMP, &now, sizeof(now));
382 static int dccp_insert_option_timestamp_echo(struct dccp_sock *dp,
383 struct dccp_request_sock *dreq,
388 u32 elapsed_time, elapsed_time_len, len;
391 elapsed_time = dccp_timestamp() - dreq->dreq_timestamp_time;
392 tstamp_echo = htonl(dreq->dreq_timestamp_echo);
393 dreq->dreq_timestamp_echo = 0;
395 elapsed_time = dccp_timestamp() - dp->dccps_timestamp_time;
396 tstamp_echo = htonl(dp->dccps_timestamp_echo);
397 dp->dccps_timestamp_echo = 0;
400 elapsed_time_len = dccp_elapsed_time_len(elapsed_time);
401 len = 6 + elapsed_time_len;
403 if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)
406 DCCP_SKB_CB(skb)->dccpd_opt_len += len;
408 to = skb_push(skb, len);
409 *to++ = DCCPO_TIMESTAMP_ECHO;
412 memcpy(to, &tstamp_echo, 4);
415 if (elapsed_time_len == 2) {
416 const __be16 var16 = htons((u16)elapsed_time);
417 memcpy(to, &var16, 2);
418 } else if (elapsed_time_len == 4) {
419 const __be32 var32 = htonl(elapsed_time);
420 memcpy(to, &var32, 4);
426 static int dccp_insert_option_ackvec(struct sock *sk, struct sk_buff *skb)
428 struct dccp_sock *dp = dccp_sk(sk);
429 struct dccp_ackvec *av = dp->dccps_hc_rx_ackvec;
430 const u16 buflen = dccp_ackvec_buflen(av);
431 /* Figure out how many options do we need to represent the ackvec */
432 const u8 nr_opts = DIV_ROUND_UP(buflen, DCCP_SINGLE_OPT_MAXLEN);
433 u16 len = buflen + 2 * nr_opts;
435 const unsigned char *tail, *from;
438 if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)
441 DCCP_SKB_CB(skb)->dccpd_opt_len += len;
443 to = skb_push(skb, len);
445 from = av->av_buf + av->av_buf_head;
446 tail = av->av_buf + DCCPAV_MAX_ACKVEC_LEN;
448 for (i = 0; i < nr_opts; ++i) {
451 if (len > DCCP_SINGLE_OPT_MAXLEN)
452 copylen = DCCP_SINGLE_OPT_MAXLEN;
455 * RFC 4340, 12.2: Encode the Nonce Echo for this Ack Vector via
456 * its type; ack_nonce is the sum of all individual buf_nonce's.
458 nonce ^= av->av_buf_nonce[i];
460 *to++ = DCCPO_ACK_VECTOR_0 + av->av_buf_nonce[i];
463 /* Check if buf_head wraps */
464 if (from + copylen > tail) {
465 const u16 tailsize = tail - from;
467 memcpy(to, from, tailsize);
474 memcpy(to, from, copylen);
480 * Each sent Ack Vector is recorded in the list, as per A.2 of RFC 4340.
482 if (dccp_ackvec_update_records(av, DCCP_SKB_CB(skb)->dccpd_seq, nonce))
488 * dccp_insert_option_mandatory - Mandatory option (5.8.2)
489 * Note that since we are using skb_push, this function needs to be called
490 * _after_ inserting the option it is supposed to influence (stack order).
492 int dccp_insert_option_mandatory(struct sk_buff *skb)
494 if (DCCP_SKB_CB(skb)->dccpd_opt_len >= DCCP_MAX_OPT_LEN)
497 DCCP_SKB_CB(skb)->dccpd_opt_len++;
498 *skb_push(skb, 1) = DCCPO_MANDATORY;
503 * dccp_insert_fn_opt - Insert single Feature-Negotiation option into @skb
504 * @type: %DCCPO_CHANGE_L, %DCCPO_CHANGE_R, %DCCPO_CONFIRM_L, %DCCPO_CONFIRM_R
505 * @feat: one out of %dccp_feature_numbers
506 * @val: NN value or SP array (preferred element first) to copy
507 * @len: true length of @val in bytes (excluding first element repetition)
508 * @repeat_first: whether to copy the first element of @val twice
509 * The last argument is used to construct Confirm options, where the preferred
510 * value and the preference list appear separately (RFC 4340, 6.3.1). Preference
511 * lists are kept such that the preferred entry is always first, so we only need
512 * to copy twice, and avoid the overhead of cloning into a bigger array.
514 int dccp_insert_fn_opt(struct sk_buff *skb, u8 type, u8 feat,
515 u8 *val, u8 len, bool repeat_first)
519 /* take the `Feature' field and possible repetition into account */
520 if (len > (DCCP_SINGLE_OPT_MAXLEN - 2)) {
521 DCCP_WARN("length %u for feature %u too large\n", len, feat);
525 if (unlikely(val == NULL || len == 0))
526 len = repeat_first = 0;
527 tot_len = 3 + repeat_first + len;
529 if (DCCP_SKB_CB(skb)->dccpd_opt_len + tot_len > DCCP_MAX_OPT_LEN) {
530 DCCP_WARN("packet too small for feature %d option!\n", feat);
533 DCCP_SKB_CB(skb)->dccpd_opt_len += tot_len;
535 to = skb_push(skb, tot_len);
543 memcpy(to, val, len);
547 /* The length of all options needs to be a multiple of 4 (5.8) */
548 static void dccp_insert_option_padding(struct sk_buff *skb)
550 int padding = DCCP_SKB_CB(skb)->dccpd_opt_len % 4;
553 padding = 4 - padding;
554 memset(skb_push(skb, padding), 0, padding);
555 DCCP_SKB_CB(skb)->dccpd_opt_len += padding;
559 int dccp_insert_options(struct sock *sk, struct sk_buff *skb)
561 struct dccp_sock *dp = dccp_sk(sk);
563 DCCP_SKB_CB(skb)->dccpd_opt_len = 0;
565 if (dp->dccps_send_ndp_count && dccp_insert_option_ndp(sk, skb))
568 if (DCCP_SKB_CB(skb)->dccpd_type != DCCP_PKT_DATA) {
570 /* Feature Negotiation */
571 if (dccp_feat_insert_opts(dp, NULL, skb))
574 if (DCCP_SKB_CB(skb)->dccpd_type == DCCP_PKT_REQUEST) {
576 * Obtain RTT sample from Request/Response exchange.
577 * This is currently used for TFRC initialisation.
579 if (dccp_insert_option_timestamp(skb))
582 } else if (dccp_ackvec_pending(sk) &&
583 dccp_insert_option_ackvec(sk, skb)) {
588 if (dp->dccps_hc_rx_insert_options) {
589 if (ccid_hc_rx_insert_options(dp->dccps_hc_rx_ccid, sk, skb))
591 dp->dccps_hc_rx_insert_options = 0;
594 if (dp->dccps_timestamp_echo != 0 &&
595 dccp_insert_option_timestamp_echo(dp, NULL, skb))
598 dccp_insert_option_padding(skb);
602 int dccp_insert_options_rsk(struct dccp_request_sock *dreq, struct sk_buff *skb)
604 DCCP_SKB_CB(skb)->dccpd_opt_len = 0;
606 if (dccp_feat_insert_opts(NULL, dreq, skb))
609 /* Obtain RTT sample from Response/Ack exchange (used by TFRC). */
610 if (dccp_insert_option_timestamp(skb))
613 if (dreq->dreq_timestamp_echo != 0 &&
614 dccp_insert_option_timestamp_echo(NULL, dreq, skb))
617 dccp_insert_option_padding(skb);