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;
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_TIMESTAMP:
133 goto out_invalid_option;
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.
139 opt_val = get_unaligned((__be32 *)value);
140 if (unlikely(opt_val == 0)) {
141 DCCP_WARN("Timestamp with zero value\n");
146 dreq->dreq_timestamp_echo = ntohl(opt_val);
147 dreq->dreq_timestamp_time = dccp_timestamp();
149 opt_recv->dccpor_timestamp =
150 dp->dccps_timestamp_echo = ntohl(opt_val);
151 dp->dccps_timestamp_time = dccp_timestamp();
153 dccp_pr_debug("%s rx opt: TIMESTAMP=%u, ackno=%llu\n",
154 dccp_role(sk), ntohl(opt_val),
156 DCCP_SKB_CB(skb)->dccpd_ack_seq);
157 /* schedule an Ack in case this sender is quiescent */
158 inet_csk_schedule_ack(sk);
160 case DCCPO_TIMESTAMP_ECHO:
161 if (len != 4 && len != 6 && len != 8)
162 goto out_invalid_option;
164 opt_val = get_unaligned((__be32 *)value);
165 opt_recv->dccpor_timestamp_echo = ntohl(opt_val);
167 dccp_pr_debug("%s rx opt: TIMESTAMP_ECHO=%u, len=%d, "
168 "ackno=%llu", dccp_role(sk),
169 opt_recv->dccpor_timestamp_echo,
172 DCCP_SKB_CB(skb)->dccpd_ack_seq);
176 if (len == 4) { /* no elapsed time included */
177 dccp_pr_debug_cat("\n");
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);
189 dccp_pr_debug_cat(", ELAPSED_TIME=%u\n", elapsed_time);
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;
195 case DCCPO_ELAPSED_TIME:
196 if (dccp_packet_without_ack(skb)) /* RFC 4340, 13.2 */
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);
206 goto out_invalid_option;
209 if (elapsed_time > opt_recv->dccpor_elapsed_time)
210 opt_recv->dccpor_elapsed_time = elapsed_time;
212 dccp_pr_debug("%s rx opt: ELAPSED_TIME=%d\n",
213 dccp_role(sk), elapsed_time);
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;
220 case DCCPO_ACK_VECTOR_0:
221 case DCCPO_ACK_VECTOR_1:
222 if (dccp_packet_without_ack(skb)) /* RFC 4340, 11.4 */
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.
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;
236 DCCP_CRIT("DCCP(%p): option %d(len=%d) not "
237 "implemented, ignoring", sk, opt, len);
241 if (opt != DCCPO_MANDATORY)
245 /* mandatory was the last byte in option list -> reset connection */
247 goto out_invalid_option;
249 out_nonsensical_length:
250 /* RFC 4340, 5.8: ignore option and all remaining option space */
254 DCCP_INC_STATS_BH(DCCP_MIB_INVALIDOPT);
255 rc = DCCP_RESET_CODE_OPTION_ERROR;
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;
265 EXPORT_SYMBOL_GPL(dccp_parse_options);
267 void dccp_encode_value_var(const u64 value, u8 *to, const u8 len)
269 if (len >= DCCP_OPTVAL_MAXLEN)
270 *to++ = (value & 0xFF0000000000ull) >> 40;
272 *to++ = (value & 0xFF00000000ull) >> 32;
274 *to++ = (value & 0xFF000000) >> 24;
276 *to++ = (value & 0xFF0000) >> 16;
278 *to++ = (value & 0xFF00) >> 8;
280 *to++ = (value & 0xFF);
283 static inline u8 dccp_ndp_len(const u64 ndp)
285 if (likely(ndp <= 0xFF))
287 return likely(ndp <= USHORT_MAX) ? 2 : (ndp <= UINT_MAX ? 4 : 6);
290 int dccp_insert_option(struct sock *sk, struct sk_buff *skb,
291 const unsigned char option,
292 const void *value, const unsigned char len)
296 if (DCCP_SKB_CB(skb)->dccpd_opt_len + len + 2 > DCCP_MAX_OPT_LEN)
299 DCCP_SKB_CB(skb)->dccpd_opt_len += len + 2;
301 to = skb_push(skb, len + 2);
305 memcpy(to, value, len);
309 EXPORT_SYMBOL_GPL(dccp_insert_option);
311 static int dccp_insert_option_ndp(struct sock *sk, struct sk_buff *skb)
313 struct dccp_sock *dp = dccp_sk(sk);
314 u64 ndp = dp->dccps_ndp_count;
316 if (dccp_non_data_packet(skb))
317 ++dp->dccps_ndp_count;
319 dp->dccps_ndp_count = 0;
323 const int ndp_len = dccp_ndp_len(ndp);
324 const int len = ndp_len + 2;
326 if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)
329 DCCP_SKB_CB(skb)->dccpd_opt_len += len;
331 ptr = skb_push(skb, len);
332 *ptr++ = DCCPO_NDP_COUNT;
334 dccp_encode_value_var(ndp, ptr, ndp_len);
340 static inline int dccp_elapsed_time_len(const u32 elapsed_time)
342 return elapsed_time == 0 ? 0 : elapsed_time <= 0xFFFF ? 2 : 4;
345 int dccp_insert_option_elapsed_time(struct sock *sk, struct sk_buff *skb,
348 const int elapsed_time_len = dccp_elapsed_time_len(elapsed_time);
349 const int len = 2 + elapsed_time_len;
352 if (elapsed_time_len == 0)
355 if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)
358 DCCP_SKB_CB(skb)->dccpd_opt_len += len;
360 to = skb_push(skb, len);
361 *to++ = DCCPO_ELAPSED_TIME;
364 if (elapsed_time_len == 2) {
365 const __be16 var16 = htons((u16)elapsed_time);
366 memcpy(to, &var16, 2);
368 const __be32 var32 = htonl(elapsed_time);
369 memcpy(to, &var32, 4);
375 EXPORT_SYMBOL_GPL(dccp_insert_option_elapsed_time);
377 int dccp_insert_option_timestamp(struct sock *sk, struct sk_buff *skb)
379 __be32 now = htonl(dccp_timestamp());
380 /* yes this will overflow but that is the point as we want a
381 * 10 usec 32 bit timer which mean it wraps every 11.9 hours */
383 return dccp_insert_option(sk, skb, DCCPO_TIMESTAMP, &now, sizeof(now));
386 EXPORT_SYMBOL_GPL(dccp_insert_option_timestamp);
388 static int dccp_insert_option_timestamp_echo(struct dccp_sock *dp,
389 struct dccp_request_sock *dreq,
394 u32 elapsed_time, elapsed_time_len, len;
397 elapsed_time = dccp_timestamp() - dreq->dreq_timestamp_time;
398 tstamp_echo = htonl(dreq->dreq_timestamp_echo);
399 dreq->dreq_timestamp_echo = 0;
401 elapsed_time = dccp_timestamp() - dp->dccps_timestamp_time;
402 tstamp_echo = htonl(dp->dccps_timestamp_echo);
403 dp->dccps_timestamp_echo = 0;
406 elapsed_time_len = dccp_elapsed_time_len(elapsed_time);
407 len = 6 + elapsed_time_len;
409 if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)
412 DCCP_SKB_CB(skb)->dccpd_opt_len += len;
414 to = skb_push(skb, len);
415 *to++ = DCCPO_TIMESTAMP_ECHO;
418 memcpy(to, &tstamp_echo, 4);
421 if (elapsed_time_len == 2) {
422 const __be16 var16 = htons((u16)elapsed_time);
423 memcpy(to, &var16, 2);
424 } else if (elapsed_time_len == 4) {
425 const __be32 var32 = htonl(elapsed_time);
426 memcpy(to, &var32, 4);
432 static int dccp_insert_option_ackvec(struct sock *sk, struct sk_buff *skb)
434 struct dccp_sock *dp = dccp_sk(sk);
435 struct dccp_ackvec *av = dp->dccps_hc_rx_ackvec;
436 struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
437 const u16 buflen = dccp_ackvec_buflen(av);
438 /* Figure out how many options do we need to represent the ackvec */
439 const u8 nr_opts = DIV_ROUND_UP(buflen, DCCP_SINGLE_OPT_MAXLEN);
440 u16 len = buflen + 2 * nr_opts;
442 const unsigned char *tail, *from;
445 if (dcb->dccpd_opt_len + len > DCCP_MAX_OPT_LEN) {
446 DCCP_WARN("Lacking space for %u bytes on %s packet\n", len,
447 dccp_packet_name(dcb->dccpd_type));
451 * Since Ack Vectors are variable-length, we can not always predict
452 * their size. To catch exception cases where the space is running out
453 * on the skb, a separate Sync is scheduled to carry the Ack Vector.
455 if (len > DCCPAV_MIN_OPTLEN &&
456 len + dcb->dccpd_opt_len + skb->len > dp->dccps_mss_cache) {
457 DCCP_WARN("No space left for Ack Vector (%u) on skb (%u+%u), "
458 "MPS=%u ==> reduce payload size?\n", len, skb->len,
459 dcb->dccpd_opt_len, dp->dccps_mss_cache);
460 dp->dccps_sync_scheduled = 1;
463 dcb->dccpd_opt_len += len;
465 to = skb_push(skb, len);
467 from = av->av_buf + av->av_buf_head;
468 tail = av->av_buf + DCCPAV_MAX_ACKVEC_LEN;
470 for (i = 0; i < nr_opts; ++i) {
473 if (len > DCCP_SINGLE_OPT_MAXLEN)
474 copylen = DCCP_SINGLE_OPT_MAXLEN;
477 * RFC 4340, 12.2: Encode the Nonce Echo for this Ack Vector via
478 * its type; ack_nonce is the sum of all individual buf_nonce's.
480 nonce ^= av->av_buf_nonce[i];
482 *to++ = DCCPO_ACK_VECTOR_0 + av->av_buf_nonce[i];
485 /* Check if buf_head wraps */
486 if (from + copylen > tail) {
487 const u16 tailsize = tail - from;
489 memcpy(to, from, tailsize);
496 memcpy(to, from, copylen);
502 * Each sent Ack Vector is recorded in the list, as per A.2 of RFC 4340.
504 if (dccp_ackvec_update_records(av, dcb->dccpd_seq, nonce))
510 * dccp_insert_option_mandatory - Mandatory option (5.8.2)
511 * Note that since we are using skb_push, this function needs to be called
512 * _after_ inserting the option it is supposed to influence (stack order).
514 int dccp_insert_option_mandatory(struct sk_buff *skb)
516 if (DCCP_SKB_CB(skb)->dccpd_opt_len >= DCCP_MAX_OPT_LEN)
519 DCCP_SKB_CB(skb)->dccpd_opt_len++;
520 *skb_push(skb, 1) = DCCPO_MANDATORY;
525 * dccp_insert_fn_opt - Insert single Feature-Negotiation option into @skb
526 * @type: %DCCPO_CHANGE_L, %DCCPO_CHANGE_R, %DCCPO_CONFIRM_L, %DCCPO_CONFIRM_R
527 * @feat: one out of %dccp_feature_numbers
528 * @val: NN value or SP array (preferred element first) to copy
529 * @len: true length of @val in bytes (excluding first element repetition)
530 * @repeat_first: whether to copy the first element of @val twice
531 * The last argument is used to construct Confirm options, where the preferred
532 * value and the preference list appear separately (RFC 4340, 6.3.1). Preference
533 * lists are kept such that the preferred entry is always first, so we only need
534 * to copy twice, and avoid the overhead of cloning into a bigger array.
536 int dccp_insert_fn_opt(struct sk_buff *skb, u8 type, u8 feat,
537 u8 *val, u8 len, bool repeat_first)
541 /* take the `Feature' field and possible repetition into account */
542 if (len > (DCCP_SINGLE_OPT_MAXLEN - 2)) {
543 DCCP_WARN("length %u for feature %u too large\n", len, feat);
547 if (unlikely(val == NULL || len == 0))
548 len = repeat_first = 0;
549 tot_len = 3 + repeat_first + len;
551 if (DCCP_SKB_CB(skb)->dccpd_opt_len + tot_len > DCCP_MAX_OPT_LEN) {
552 DCCP_WARN("packet too small for feature %d option!\n", feat);
555 DCCP_SKB_CB(skb)->dccpd_opt_len += tot_len;
557 to = skb_push(skb, tot_len);
565 memcpy(to, val, len);
569 /* The length of all options needs to be a multiple of 4 (5.8) */
570 static void dccp_insert_option_padding(struct sk_buff *skb)
572 int padding = DCCP_SKB_CB(skb)->dccpd_opt_len % 4;
575 padding = 4 - padding;
576 memset(skb_push(skb, padding), 0, padding);
577 DCCP_SKB_CB(skb)->dccpd_opt_len += padding;
581 int dccp_insert_options(struct sock *sk, struct sk_buff *skb)
583 struct dccp_sock *dp = dccp_sk(sk);
585 DCCP_SKB_CB(skb)->dccpd_opt_len = 0;
587 if (dp->dccps_send_ndp_count && dccp_insert_option_ndp(sk, skb))
590 if (DCCP_SKB_CB(skb)->dccpd_type != DCCP_PKT_DATA) {
592 /* Feature Negotiation */
593 if (dccp_feat_insert_opts(dp, NULL, skb))
596 if (DCCP_SKB_CB(skb)->dccpd_type == DCCP_PKT_REQUEST) {
598 * Obtain RTT sample from Request/Response exchange.
599 * This is currently used in CCID 3 initialisation.
601 if (dccp_insert_option_timestamp(sk, skb))
604 } else if (dccp_ackvec_pending(sk) &&
605 dccp_insert_option_ackvec(sk, skb)) {
610 if (dp->dccps_hc_rx_insert_options) {
611 if (ccid_hc_rx_insert_options(dp->dccps_hc_rx_ccid, sk, skb))
613 dp->dccps_hc_rx_insert_options = 0;
616 if (dp->dccps_timestamp_echo != 0 &&
617 dccp_insert_option_timestamp_echo(dp, NULL, skb))
620 dccp_insert_option_padding(skb);
624 int dccp_insert_options_rsk(struct dccp_request_sock *dreq, struct sk_buff *skb)
626 DCCP_SKB_CB(skb)->dccpd_opt_len = 0;
628 if (dccp_feat_insert_opts(NULL, dreq, skb))
631 if (dreq->dreq_timestamp_echo != 0 &&
632 dccp_insert_option_timestamp_echo(NULL, dreq, skb))
635 dccp_insert_option_padding(skb);