1// SPDX-License-Identifier: GPL-2.0-or-later 2/* 3 * Copyright (c) 2007 The University of Aberdeen, Scotland, UK 4 * Copyright (c) 2005-7 The University of Waikato, Hamilton, New Zealand. 5 * Copyright (c) 2005-7 Ian McDonald <ian.mcdonald@jandi.co.nz> 6 * 7 * An implementation of the DCCP protocol 8 * 9 * This code has been developed by the University of Waikato WAND 10 * research group. For further information please see https://www.wand.net.nz/ 11 * 12 * This code also uses code from Lulea University, rereleased as GPL by its 13 * authors: 14 * Copyright (c) 2003 Nils-Erik Mattsson, Joacim Haggmark, Magnus Erixzon 15 * 16 * Changes to meet Linux coding standards, to make it meet latest ccid3 draft 17 * and to make it work as a loadable module in the DCCP stack written by 18 * Arnaldo Carvalho de Melo <acme@conectiva.com.br>. 19 * 20 * Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@conectiva.com.br> 21 */ 22#include "../dccp.h" 23#include "ccid3.h" 24 25#include <asm/unaligned.h> 26 27#ifdef CONFIG_IP_DCCP_CCID3_DEBUG 28static bool ccid3_debug; 29#define ccid3_pr_debug(format, a...) DCCP_PR_DEBUG(ccid3_debug, format, ##a) 30#else 31#define ccid3_pr_debug(format, a...) 32#endif 33 34/* 35 * Transmitter Half-Connection Routines 36 */ 37#ifdef CONFIG_IP_DCCP_CCID3_DEBUG 38static const char *ccid3_tx_state_name(enum ccid3_hc_tx_states state) 39{ 40 static const char *const ccid3_state_names[] = { 41 [TFRC_SSTATE_NO_SENT] = "NO_SENT", 42 [TFRC_SSTATE_NO_FBACK] = "NO_FBACK", 43 [TFRC_SSTATE_FBACK] = "FBACK", 44 }; 45 46 return ccid3_state_names[state]; 47} 48#endif 49 50static void ccid3_hc_tx_set_state(struct sock *sk, 51 enum ccid3_hc_tx_states state) 52{ 53 struct ccid3_hc_tx_sock *hc = ccid3_hc_tx_sk(sk); 54 enum ccid3_hc_tx_states oldstate = hc->tx_state; 55 56 ccid3_pr_debug("%s(%p) %-8.8s -> %s\n", 57 dccp_role(sk), sk, ccid3_tx_state_name(oldstate), 58 ccid3_tx_state_name(state)); 59 WARN_ON(state == oldstate); 60 hc->tx_state = state; 61} 62 63/* 64 * Compute the initial sending rate X_init in the manner of RFC 3390: 65 * 66 * X_init = min(4 * s, max(2 * s, 4380 bytes)) / RTT 67 * 68 * Note that RFC 3390 uses MSS, RFC 4342 refers to RFC 3390, and rfc3448bis 69 * (rev-02) clarifies the use of RFC 3390 with regard to the above formula. 70 * For consistency with other parts of the code, X_init is scaled by 2^6. 71 */ 72static inline u64 rfc3390_initial_rate(struct sock *sk) 73{ 74 const struct ccid3_hc_tx_sock *hc = ccid3_hc_tx_sk(sk); 75 const __u32 w_init = clamp_t(__u32, 4380U, 2 * hc->tx_s, 4 * hc->tx_s); 76 77 return scaled_div(w_init << 6, hc->tx_rtt); 78} 79 80/** 81 * ccid3_update_send_interval - Calculate new t_ipi = s / X_inst 82 * @hc: socket to have the send interval updated 83 * 84 * This respects the granularity of X_inst (64 * bytes/second). 85 */ 86static void ccid3_update_send_interval(struct ccid3_hc_tx_sock *hc) 87{ 88 hc->tx_t_ipi = scaled_div32(((u64)hc->tx_s) << 6, hc->tx_x); 89 90 DCCP_BUG_ON(hc->tx_t_ipi == 0); 91 ccid3_pr_debug("t_ipi=%u, s=%u, X=%u\n", hc->tx_t_ipi, 92 hc->tx_s, (unsigned int)(hc->tx_x >> 6)); 93} 94 95static u32 ccid3_hc_tx_idle_rtt(struct ccid3_hc_tx_sock *hc, ktime_t now) 96{ 97 u32 delta = ktime_us_delta(now, hc->tx_t_last_win_count); 98 99 return delta / hc->tx_rtt; 100} 101 102/** 103 * ccid3_hc_tx_update_x - Update allowed sending rate X 104 * @sk: socket to be updated 105 * @stamp: most recent time if available - can be left NULL. 106 * 107 * This function tracks draft rfc3448bis, check there for latest details. 108 * 109 * Note: X and X_recv are both stored in units of 64 * bytes/second, to support 110 * fine-grained resolution of sending rates. This requires scaling by 2^6 111 * throughout the code. Only X_calc is unscaled (in bytes/second). 112 * 113 */ 114static void ccid3_hc_tx_update_x(struct sock *sk, ktime_t *stamp) 115{ 116 struct ccid3_hc_tx_sock *hc = ccid3_hc_tx_sk(sk); 117 __u64 min_rate = 2 * hc->tx_x_recv; 118 const __u64 old_x = hc->tx_x; 119 ktime_t now = stamp ? *stamp : ktime_get_real(); 120 121 /* 122 * Handle IDLE periods: do not reduce below RFC3390 initial sending rate 123 * when idling [RFC 4342, 5.1]. Definition of idling is from rfc3448bis: 124 * a sender is idle if it has not sent anything over a 2-RTT-period. 125 * For consistency with X and X_recv, min_rate is also scaled by 2^6. 126 */ 127 if (ccid3_hc_tx_idle_rtt(hc, now) >= 2) { 128 min_rate = rfc3390_initial_rate(sk); 129 min_rate = max(min_rate, 2 * hc->tx_x_recv); 130 } 131 132 if (hc->tx_p > 0) { 133 134 hc->tx_x = min(((__u64)hc->tx_x_calc) << 6, min_rate); 135 hc->tx_x = max(hc->tx_x, (((__u64)hc->tx_s) << 6) / TFRC_T_MBI); 136 137 } else if (ktime_us_delta(now, hc->tx_t_ld) - (s64)hc->tx_rtt >= 0) { 138 139 hc->tx_x = min(2 * hc->tx_x, min_rate); 140 hc->tx_x = max(hc->tx_x, 141 scaled_div(((__u64)hc->tx_s) << 6, hc->tx_rtt)); 142 hc->tx_t_ld = now; 143 } 144 145 if (hc->tx_x != old_x) { 146 ccid3_pr_debug("X_prev=%u, X_now=%u, X_calc=%u, " 147 "X_recv=%u\n", (unsigned int)(old_x >> 6), 148 (unsigned int)(hc->tx_x >> 6), hc->tx_x_calc, 149 (unsigned int)(hc->tx_x_recv >> 6)); 150 151 ccid3_update_send_interval(hc); 152 } 153} 154 155/** 156 * ccid3_hc_tx_update_s - Track the mean packet size `s' 157 * @hc: socket to be updated 158 * @len: DCCP packet payload size in bytes 159 * 160 * cf. RFC 4342, 5.3 and RFC 3448, 4.1 161 */ 162static inline void ccid3_hc_tx_update_s(struct ccid3_hc_tx_sock *hc, int len) 163{ 164 const u16 old_s = hc->tx_s; 165 166 hc->tx_s = tfrc_ewma(hc->tx_s, len, 9); 167 168 if (hc->tx_s != old_s) 169 ccid3_update_send_interval(hc); 170} 171 172/* 173 * Update Window Counter using the algorithm from [RFC 4342, 8.1]. 174 * As elsewhere, RTT > 0 is assumed by using dccp_sample_rtt(). 175 */ 176static inline void ccid3_hc_tx_update_win_count(struct ccid3_hc_tx_sock *hc, 177 ktime_t now) 178{ 179 u32 delta = ktime_us_delta(now, hc->tx_t_last_win_count), 180 quarter_rtts = (4 * delta) / hc->tx_rtt; 181 182 if (quarter_rtts > 0) { 183 hc->tx_t_last_win_count = now; 184 hc->tx_last_win_count += min(quarter_rtts, 5U); 185 hc->tx_last_win_count &= 0xF; /* mod 16 */ 186 } 187} 188 189static void ccid3_hc_tx_no_feedback_timer(struct timer_list *t) 190{ 191 struct ccid3_hc_tx_sock *hc = from_timer(hc, t, tx_no_feedback_timer); 192 struct sock *sk = hc->sk; 193 unsigned long t_nfb = USEC_PER_SEC / 5; 194 195 bh_lock_sock(sk); 196 if (sock_owned_by_user(sk)) { 197 /* Try again later. */ 198 /* XXX: set some sensible MIB */ 199 goto restart_timer; 200 } 201 202 ccid3_pr_debug("%s(%p, state=%s) - entry\n", dccp_role(sk), sk, 203 ccid3_tx_state_name(hc->tx_state)); 204 205 /* Ignore and do not restart after leaving the established state */ 206 if ((1 << sk->sk_state) & ~(DCCPF_OPEN | DCCPF_PARTOPEN)) 207 goto out; 208 209 /* Reset feedback state to "no feedback received" */ 210 if (hc->tx_state == TFRC_SSTATE_FBACK) 211 ccid3_hc_tx_set_state(sk, TFRC_SSTATE_NO_FBACK); 212 213 /* 214 * Determine new allowed sending rate X as per draft rfc3448bis-00, 4.4 215 * RTO is 0 if and only if no feedback has been received yet. 216 */ 217 if (hc->tx_t_rto == 0 || hc->tx_p == 0) { 218 219 /* halve send rate directly */ 220 hc->tx_x = max(hc->tx_x / 2, 221 (((__u64)hc->tx_s) << 6) / TFRC_T_MBI); 222 ccid3_update_send_interval(hc); 223 } else { 224 /* 225 * Modify the cached value of X_recv 226 * 227 * If (X_calc > 2 * X_recv) 228 * X_recv = max(X_recv / 2, s / (2 * t_mbi)); 229 * Else 230 * X_recv = X_calc / 4; 231 * 232 * Note that X_recv is scaled by 2^6 while X_calc is not 233 */ 234 if (hc->tx_x_calc > (hc->tx_x_recv >> 5)) 235 hc->tx_x_recv = 236 max(hc->tx_x_recv / 2, 237 (((__u64)hc->tx_s) << 6) / (2*TFRC_T_MBI)); 238 else { 239 hc->tx_x_recv = hc->tx_x_calc; 240 hc->tx_x_recv <<= 4; 241 } 242 ccid3_hc_tx_update_x(sk, NULL); 243 } 244 ccid3_pr_debug("Reduced X to %llu/64 bytes/sec\n", 245 (unsigned long long)hc->tx_x); 246 247 /* 248 * Set new timeout for the nofeedback timer. 249 * See comments in packet_recv() regarding the value of t_RTO. 250 */ 251 if (unlikely(hc->tx_t_rto == 0)) /* no feedback received yet */ 252 t_nfb = TFRC_INITIAL_TIMEOUT; 253 else 254 t_nfb = max(hc->tx_t_rto, 2 * hc->tx_t_ipi); 255 256restart_timer: 257 sk_reset_timer(sk, &hc->tx_no_feedback_timer, 258 jiffies + usecs_to_jiffies(t_nfb)); 259out: 260 bh_unlock_sock(sk); 261 sock_put(sk); 262} 263 264/** 265 * ccid3_hc_tx_send_packet - Delay-based dequeueing of TX packets 266 * @sk: socket to send packet from 267 * @skb: next packet candidate to send on @sk 268 * 269 * This function uses the convention of ccid_packet_dequeue_eval() and 270 * returns a millisecond-delay value between 0 and t_mbi = 64000 msec. 271 */ 272static int ccid3_hc_tx_send_packet(struct sock *sk, struct sk_buff *skb) 273{ 274 struct dccp_sock *dp = dccp_sk(sk); 275 struct ccid3_hc_tx_sock *hc = ccid3_hc_tx_sk(sk); 276 ktime_t now = ktime_get_real(); 277 s64 delay; 278 279 /* 280 * This function is called only for Data and DataAck packets. Sending 281 * zero-sized Data(Ack)s is theoretically possible, but for congestion 282 * control this case is pathological - ignore it. 283 */ 284 if (unlikely(skb->len == 0)) 285 return -EBADMSG; 286 287 if (hc->tx_state == TFRC_SSTATE_NO_SENT) { 288 sk_reset_timer(sk, &hc->tx_no_feedback_timer, (jiffies + 289 usecs_to_jiffies(TFRC_INITIAL_TIMEOUT))); 290 hc->tx_last_win_count = 0; 291 hc->tx_t_last_win_count = now; 292 293 /* Set t_0 for initial packet */ 294 hc->tx_t_nom = now; 295 296 hc->tx_s = skb->len; 297 298 /* 299 * Use initial RTT sample when available: recommended by erratum 300 * to RFC 4342. This implements the initialisation procedure of 301 * draft rfc3448bis, section 4.2. Remember, X is scaled by 2^6. 302 */ 303 if (dp->dccps_syn_rtt) { 304 ccid3_pr_debug("SYN RTT = %uus\n", dp->dccps_syn_rtt); 305 hc->tx_rtt = dp->dccps_syn_rtt; 306 hc->tx_x = rfc3390_initial_rate(sk); 307 hc->tx_t_ld = now; 308 } else { 309 /* 310 * Sender does not have RTT sample: 311 * - set fallback RTT (RFC 4340, 3.4) since a RTT value 312 * is needed in several parts (e.g. window counter); 313 * - set sending rate X_pps = 1pps as per RFC 3448, 4.2. 314 */ 315 hc->tx_rtt = DCCP_FALLBACK_RTT; 316 hc->tx_x = hc->tx_s; 317 hc->tx_x <<= 6; 318 } 319 ccid3_update_send_interval(hc); 320 321 ccid3_hc_tx_set_state(sk, TFRC_SSTATE_NO_FBACK); 322 323 } else { 324 delay = ktime_us_delta(hc->tx_t_nom, now); 325 ccid3_pr_debug("delay=%ld\n", (long)delay); 326 /* 327 * Scheduling of packet transmissions (RFC 5348, 8.3) 328 * 329 * if (t_now > t_nom - delta) 330 * // send the packet now 331 * else 332 * // send the packet in (t_nom - t_now) milliseconds. 333 */ 334 if (delay >= TFRC_T_DELTA) 335 return (u32)delay / USEC_PER_MSEC; 336 337 ccid3_hc_tx_update_win_count(hc, now); 338 } 339 340 /* prepare to send now (add options etc.) */ 341 dp->dccps_hc_tx_insert_options = 1; 342 DCCP_SKB_CB(skb)->dccpd_ccval = hc->tx_last_win_count; 343 344 /* set the nominal send time for the next following packet */ 345 hc->tx_t_nom = ktime_add_us(hc->tx_t_nom, hc->tx_t_ipi); 346 return CCID_PACKET_SEND_AT_ONCE; 347} 348 349static void ccid3_hc_tx_packet_sent(struct sock *sk, unsigned int len) 350{ 351 struct ccid3_hc_tx_sock *hc = ccid3_hc_tx_sk(sk); 352 353 ccid3_hc_tx_update_s(hc, len); 354 355 if (tfrc_tx_hist_add(&hc->tx_hist, dccp_sk(sk)->dccps_gss)) 356 DCCP_CRIT("packet history - out of memory!"); 357} 358 359static void ccid3_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb) 360{ 361 struct ccid3_hc_tx_sock *hc = ccid3_hc_tx_sk(sk); 362 struct tfrc_tx_hist_entry *acked; 363 ktime_t now; 364 unsigned long t_nfb; 365 u32 r_sample; 366 367 /* we are only interested in ACKs */ 368 if (!(DCCP_SKB_CB(skb)->dccpd_type == DCCP_PKT_ACK || 369 DCCP_SKB_CB(skb)->dccpd_type == DCCP_PKT_DATAACK)) 370 return; 371 /* 372 * Locate the acknowledged packet in the TX history. 373 * 374 * Returning "entry not found" here can for instance happen when 375 * - the host has not sent out anything (e.g. a passive server), 376 * - the Ack is outdated (packet with higher Ack number was received), 377 * - it is a bogus Ack (for a packet not sent on this connection). 378 */ 379 acked = tfrc_tx_hist_find_entry(hc->tx_hist, dccp_hdr_ack_seq(skb)); 380 if (acked == NULL) 381 return; 382 /* For the sake of RTT sampling, ignore/remove all older entries */ 383 tfrc_tx_hist_purge(&acked->next); 384 385 /* Update the moving average for the RTT estimate (RFC 3448, 4.3) */ 386 now = ktime_get_real(); 387 r_sample = dccp_sample_rtt(sk, ktime_us_delta(now, acked->stamp)); 388 hc->tx_rtt = tfrc_ewma(hc->tx_rtt, r_sample, 9); 389 390 /* 391 * Update allowed sending rate X as per draft rfc3448bis-00, 4.2/3 392 */ 393 if (hc->tx_state == TFRC_SSTATE_NO_FBACK) { 394 ccid3_hc_tx_set_state(sk, TFRC_SSTATE_FBACK); 395 396 if (hc->tx_t_rto == 0) { 397 /* 398 * Initial feedback packet: Larger Initial Windows (4.2) 399 */ 400 hc->tx_x = rfc3390_initial_rate(sk); 401 hc->tx_t_ld = now; 402 403 ccid3_update_send_interval(hc); 404 405 goto done_computing_x; 406 } else if (hc->tx_p == 0) { 407 /* 408 * First feedback after nofeedback timer expiry (4.3) 409 */ 410 goto done_computing_x; 411 } 412 } 413 414 /* Update sending rate (step 4 of [RFC 3448, 4.3]) */ 415 if (hc->tx_p > 0) 416 hc->tx_x_calc = tfrc_calc_x(hc->tx_s, hc->tx_rtt, hc->tx_p); 417 ccid3_hc_tx_update_x(sk, &now); 418 419done_computing_x: 420 ccid3_pr_debug("%s(%p), RTT=%uus (sample=%uus), s=%u, " 421 "p=%u, X_calc=%u, X_recv=%u, X=%u\n", 422 dccp_role(sk), sk, hc->tx_rtt, r_sample, 423 hc->tx_s, hc->tx_p, hc->tx_x_calc, 424 (unsigned int)(hc->tx_x_recv >> 6), 425 (unsigned int)(hc->tx_x >> 6)); 426 427 /* unschedule no feedback timer */ 428 sk_stop_timer(sk, &hc->tx_no_feedback_timer); 429 430 /* 431 * As we have calculated new ipi, delta, t_nom it is possible 432 * that we now can send a packet, so wake up dccp_wait_for_ccid 433 */ 434 sk->sk_write_space(sk); 435 436 /* 437 * Update timeout interval for the nofeedback timer. In order to control 438 * rate halving on networks with very low RTTs (<= 1 ms), use per-route 439 * tunable RTAX_RTO_MIN value as the lower bound. 440 */ 441 hc->tx_t_rto = max_t(u32, 4 * hc->tx_rtt, 442 USEC_PER_SEC/HZ * tcp_rto_min(sk)); 443 /* 444 * Schedule no feedback timer to expire in 445 * max(t_RTO, 2 * s/X) = max(t_RTO, 2 * t_ipi) 446 */ 447 t_nfb = max(hc->tx_t_rto, 2 * hc->tx_t_ipi); 448 449 ccid3_pr_debug("%s(%p), Scheduled no feedback timer to " 450 "expire in %lu jiffies (%luus)\n", 451 dccp_role(sk), sk, usecs_to_jiffies(t_nfb), t_nfb); 452 453 sk_reset_timer(sk, &hc->tx_no_feedback_timer, 454 jiffies + usecs_to_jiffies(t_nfb)); 455} 456 457static int ccid3_hc_tx_parse_options(struct sock *sk, u8 packet_type, 458 u8 option, u8 *optval, u8 optlen) 459{ 460 struct ccid3_hc_tx_sock *hc = ccid3_hc_tx_sk(sk); 461 __be32 opt_val; 462 463 switch (option) { 464 case TFRC_OPT_RECEIVE_RATE: 465 case TFRC_OPT_LOSS_EVENT_RATE: 466 /* Must be ignored on Data packets, cf. RFC 4342 8.3 and 8.5 */ 467 if (packet_type == DCCP_PKT_DATA) 468 break; 469 if (unlikely(optlen != 4)) { 470 DCCP_WARN("%s(%p), invalid len %d for %u\n", 471 dccp_role(sk), sk, optlen, option); 472 return -EINVAL; 473 } 474 opt_val = ntohl(get_unaligned((__be32 *)optval)); 475 476 if (option == TFRC_OPT_RECEIVE_RATE) { 477 /* Receive Rate is kept in units of 64 bytes/second */ 478 hc->tx_x_recv = opt_val; 479 hc->tx_x_recv <<= 6; 480 481 ccid3_pr_debug("%s(%p), RECEIVE_RATE=%u\n", 482 dccp_role(sk), sk, opt_val); 483 } else { 484 /* Update the fixpoint Loss Event Rate fraction */ 485 hc->tx_p = tfrc_invert_loss_event_rate(opt_val); 486 487 ccid3_pr_debug("%s(%p), LOSS_EVENT_RATE=%u\n", 488 dccp_role(sk), sk, opt_val); 489 } 490 } 491 return 0; 492} 493 494static int ccid3_hc_tx_init(struct ccid *ccid, struct sock *sk) 495{ 496 struct ccid3_hc_tx_sock *hc = ccid_priv(ccid); 497 498 hc->tx_state = TFRC_SSTATE_NO_SENT; 499 hc->tx_hist = NULL; 500 hc->sk = sk; 501 timer_setup(&hc->tx_no_feedback_timer, 502 ccid3_hc_tx_no_feedback_timer, 0); 503 return 0; 504} 505 506static void ccid3_hc_tx_exit(struct sock *sk) 507{ 508 struct ccid3_hc_tx_sock *hc = ccid3_hc_tx_sk(sk); 509 510 sk_stop_timer(sk, &hc->tx_no_feedback_timer); 511 tfrc_tx_hist_purge(&hc->tx_hist); 512} 513 514static void ccid3_hc_tx_get_info(struct sock *sk, struct tcp_info *info) 515{ 516 info->tcpi_rto = ccid3_hc_tx_sk(sk)->tx_t_rto; 517 info->tcpi_rtt = ccid3_hc_tx_sk(sk)->tx_rtt; 518} 519 520static int ccid3_hc_tx_getsockopt(struct sock *sk, const int optname, int len, 521 u32 __user *optval, int __user *optlen) 522{ 523 const struct ccid3_hc_tx_sock *hc = ccid3_hc_tx_sk(sk); 524 struct tfrc_tx_info tfrc; 525 const void *val; 526 527 switch (optname) { 528 case DCCP_SOCKOPT_CCID_TX_INFO: 529 if (len < sizeof(tfrc)) 530 return -EINVAL; 531 memset(&tfrc, 0, sizeof(tfrc)); 532 tfrc.tfrctx_x = hc->tx_x; 533 tfrc.tfrctx_x_recv = hc->tx_x_recv; 534 tfrc.tfrctx_x_calc = hc->tx_x_calc; 535 tfrc.tfrctx_rtt = hc->tx_rtt; 536 tfrc.tfrctx_p = hc->tx_p; 537 tfrc.tfrctx_rto = hc->tx_t_rto; 538 tfrc.tfrctx_ipi = hc->tx_t_ipi; 539 len = sizeof(tfrc); 540 val = &tfrc; 541 break; 542 default: 543 return -ENOPROTOOPT; 544 } 545 546 if (put_user(len, optlen) || copy_to_user(optval, val, len)) 547 return -EFAULT; 548 549 return 0; 550} 551 552/* 553 * Receiver Half-Connection Routines 554 */ 555 556/* CCID3 feedback types */ 557enum ccid3_fback_type { 558 CCID3_FBACK_NONE = 0, 559 CCID3_FBACK_INITIAL, 560 CCID3_FBACK_PERIODIC, 561 CCID3_FBACK_PARAM_CHANGE 562}; 563 564#ifdef CONFIG_IP_DCCP_CCID3_DEBUG 565static const char *ccid3_rx_state_name(enum ccid3_hc_rx_states state) 566{ 567 static const char *const ccid3_rx_state_names[] = { 568 [TFRC_RSTATE_NO_DATA] = "NO_DATA", 569 [TFRC_RSTATE_DATA] = "DATA", 570 }; 571 572 return ccid3_rx_state_names[state]; 573} 574#endif 575 576static void ccid3_hc_rx_set_state(struct sock *sk, 577 enum ccid3_hc_rx_states state) 578{ 579 struct ccid3_hc_rx_sock *hc = ccid3_hc_rx_sk(sk); 580 enum ccid3_hc_rx_states oldstate = hc->rx_state; 581 582 ccid3_pr_debug("%s(%p) %-8.8s -> %s\n", 583 dccp_role(sk), sk, ccid3_rx_state_name(oldstate), 584 ccid3_rx_state_name(state)); 585 WARN_ON(state == oldstate); 586 hc->rx_state = state; 587} 588 589static void ccid3_hc_rx_send_feedback(struct sock *sk, 590 const struct sk_buff *skb, 591 enum ccid3_fback_type fbtype) 592{ 593 struct ccid3_hc_rx_sock *hc = ccid3_hc_rx_sk(sk); 594 struct dccp_sock *dp = dccp_sk(sk); 595 ktime_t now = ktime_get(); 596 s64 delta = 0; 597 598 switch (fbtype) { 599 case CCID3_FBACK_INITIAL: 600 hc->rx_x_recv = 0; 601 hc->rx_pinv = ~0U; /* see RFC 4342, 8.5 */ 602 break; 603 case CCID3_FBACK_PARAM_CHANGE: 604 /* 605 * When parameters change (new loss or p > p_prev), we do not 606 * have a reliable estimate for R_m of [RFC 3448, 6.2] and so 607 * need to reuse the previous value of X_recv. However, when 608 * X_recv was 0 (due to early loss), this would kill X down to 609 * s/t_mbi (i.e. one packet in 64 seconds). 610 * To avoid such drastic reduction, we approximate X_recv as 611 * the number of bytes since last feedback. 612 * This is a safe fallback, since X is bounded above by X_calc. 613 */ 614 if (hc->rx_x_recv > 0) 615 break; 616 fallthrough; 617 case CCID3_FBACK_PERIODIC: 618 delta = ktime_us_delta(now, hc->rx_tstamp_last_feedback); 619 if (delta <= 0) 620 delta = 1; 621 hc->rx_x_recv = scaled_div32(hc->rx_bytes_recv, delta); 622 break; 623 default: 624 return; 625 } 626 627 ccid3_pr_debug("Interval %lldusec, X_recv=%u, 1/p=%u\n", delta, 628 hc->rx_x_recv, hc->rx_pinv); 629 630 hc->rx_tstamp_last_feedback = now; 631 hc->rx_last_counter = dccp_hdr(skb)->dccph_ccval; 632 hc->rx_bytes_recv = 0; 633 634 dp->dccps_hc_rx_insert_options = 1; 635 dccp_send_ack(sk); 636} 637 638static int ccid3_hc_rx_insert_options(struct sock *sk, struct sk_buff *skb) 639{ 640 const struct ccid3_hc_rx_sock *hc = ccid3_hc_rx_sk(sk); 641 __be32 x_recv, pinv; 642 643 if (!(sk->sk_state == DCCP_OPEN || sk->sk_state == DCCP_PARTOPEN)) 644 return 0; 645 646 if (dccp_packet_without_ack(skb)) 647 return 0; 648 649 x_recv = htonl(hc->rx_x_recv); 650 pinv = htonl(hc->rx_pinv); 651 652 if (dccp_insert_option(skb, TFRC_OPT_LOSS_EVENT_RATE, 653 &pinv, sizeof(pinv)) || 654 dccp_insert_option(skb, TFRC_OPT_RECEIVE_RATE, 655 &x_recv, sizeof(x_recv))) 656 return -1; 657 658 return 0; 659} 660 661/** 662 * ccid3_first_li - Implements [RFC 5348, 6.3.1] 663 * @sk: socket to calculate loss interval for 664 * 665 * Determine the length of the first loss interval via inverse lookup. 666 * Assume that X_recv can be computed by the throughput equation 667 * s 668 * X_recv = -------- 669 * R * fval 670 * Find some p such that f(p) = fval; return 1/p (scaled). 671 */ 672static u32 ccid3_first_li(struct sock *sk) 673{ 674 struct ccid3_hc_rx_sock *hc = ccid3_hc_rx_sk(sk); 675 u32 x_recv, p; 676 s64 delta; 677 u64 fval; 678 679 if (hc->rx_rtt == 0) { 680 DCCP_WARN("No RTT estimate available, using fallback RTT\n"); 681 hc->rx_rtt = DCCP_FALLBACK_RTT; 682 } 683 684 delta = ktime_us_delta(ktime_get(), hc->rx_tstamp_last_feedback); 685 if (delta <= 0) 686 delta = 1; 687 x_recv = scaled_div32(hc->rx_bytes_recv, delta); 688 if (x_recv == 0) { /* would also trigger divide-by-zero */ 689 DCCP_WARN("X_recv==0\n"); 690 if (hc->rx_x_recv == 0) { 691 DCCP_BUG("stored value of X_recv is zero"); 692 return ~0U; 693 } 694 x_recv = hc->rx_x_recv; 695 } 696 697 fval = scaled_div(hc->rx_s, hc->rx_rtt); 698 fval = scaled_div32(fval, x_recv); 699 p = tfrc_calc_x_reverse_lookup(fval); 700 701 ccid3_pr_debug("%s(%p), receive rate=%u bytes/s, implied " 702 "loss rate=%u\n", dccp_role(sk), sk, x_recv, p); 703 704 return p == 0 ? ~0U : scaled_div(1, p); 705} 706 707static void ccid3_hc_rx_packet_recv(struct sock *sk, struct sk_buff *skb) 708{ 709 struct ccid3_hc_rx_sock *hc = ccid3_hc_rx_sk(sk); 710 enum ccid3_fback_type do_feedback = CCID3_FBACK_NONE; 711 const u64 ndp = dccp_sk(sk)->dccps_options_received.dccpor_ndp; 712 const bool is_data_packet = dccp_data_packet(skb); 713 714 if (unlikely(hc->rx_state == TFRC_RSTATE_NO_DATA)) { 715 if (is_data_packet) { 716 const u32 payload = skb->len - dccp_hdr(skb)->dccph_doff * 4; 717 do_feedback = CCID3_FBACK_INITIAL; 718 ccid3_hc_rx_set_state(sk, TFRC_RSTATE_DATA); 719 hc->rx_s = payload; 720 /* 721 * Not necessary to update rx_bytes_recv here, 722 * since X_recv = 0 for the first feedback packet (cf. 723 * RFC 3448, 6.3) -- gerrit 724 */ 725 } 726 goto update_records; 727 } 728 729 if (tfrc_rx_hist_duplicate(&hc->rx_hist, skb)) 730 return; /* done receiving */ 731 732 if (is_data_packet) { 733 const u32 payload = skb->len - dccp_hdr(skb)->dccph_doff * 4; 734 /* 735 * Update moving-average of s and the sum of received payload bytes 736 */ 737 hc->rx_s = tfrc_ewma(hc->rx_s, payload, 9); 738 hc->rx_bytes_recv += payload; 739 } 740 741 /* 742 * Perform loss detection and handle pending losses 743 */ 744 if (tfrc_rx_handle_loss(&hc->rx_hist, &hc->rx_li_hist, 745 skb, ndp, ccid3_first_li, sk)) { 746 do_feedback = CCID3_FBACK_PARAM_CHANGE; 747 goto done_receiving; 748 } 749 750 if (tfrc_rx_hist_loss_pending(&hc->rx_hist)) 751 return; /* done receiving */ 752 753 /* 754 * Handle data packets: RTT sampling and monitoring p 755 */ 756 if (unlikely(!is_data_packet)) 757 goto update_records; 758 759 if (!tfrc_lh_is_initialised(&hc->rx_li_hist)) { 760 const u32 sample = tfrc_rx_hist_sample_rtt(&hc->rx_hist, skb); 761 /* 762 * Empty loss history: no loss so far, hence p stays 0. 763 * Sample RTT values, since an RTT estimate is required for the 764 * computation of p when the first loss occurs; RFC 3448, 6.3.1. 765 */ 766 if (sample != 0) 767 hc->rx_rtt = tfrc_ewma(hc->rx_rtt, sample, 9); 768 769 } else if (tfrc_lh_update_i_mean(&hc->rx_li_hist, skb)) { 770 /* 771 * Step (3) of [RFC 3448, 6.1]: Recompute I_mean and, if I_mean 772 * has decreased (resp. p has increased), send feedback now. 773 */ 774 do_feedback = CCID3_FBACK_PARAM_CHANGE; 775 } 776 777 /* 778 * Check if the periodic once-per-RTT feedback is due; RFC 4342, 10.3 779 */ 780 if (SUB16(dccp_hdr(skb)->dccph_ccval, hc->rx_last_counter) > 3) 781 do_feedback = CCID3_FBACK_PERIODIC; 782 783update_records: 784 tfrc_rx_hist_add_packet(&hc->rx_hist, skb, ndp); 785 786done_receiving: 787 if (do_feedback) 788 ccid3_hc_rx_send_feedback(sk, skb, do_feedback); 789} 790 791static int ccid3_hc_rx_init(struct ccid *ccid, struct sock *sk) 792{ 793 struct ccid3_hc_rx_sock *hc = ccid_priv(ccid); 794 795 hc->rx_state = TFRC_RSTATE_NO_DATA; 796 tfrc_lh_init(&hc->rx_li_hist); 797 return tfrc_rx_hist_alloc(&hc->rx_hist); 798} 799 800static void ccid3_hc_rx_exit(struct sock *sk) 801{ 802 struct ccid3_hc_rx_sock *hc = ccid3_hc_rx_sk(sk); 803 804 tfrc_rx_hist_purge(&hc->rx_hist); 805 tfrc_lh_cleanup(&hc->rx_li_hist); 806} 807 808static void ccid3_hc_rx_get_info(struct sock *sk, struct tcp_info *info) 809{ 810 info->tcpi_ca_state = ccid3_hc_rx_sk(sk)->rx_state; 811 info->tcpi_options |= TCPI_OPT_TIMESTAMPS; 812 info->tcpi_rcv_rtt = ccid3_hc_rx_sk(sk)->rx_rtt; 813} 814 815static int ccid3_hc_rx_getsockopt(struct sock *sk, const int optname, int len, 816 u32 __user *optval, int __user *optlen) 817{ 818 const struct ccid3_hc_rx_sock *hc = ccid3_hc_rx_sk(sk); 819 struct tfrc_rx_info rx_info; 820 const void *val; 821 822 switch (optname) { 823 case DCCP_SOCKOPT_CCID_RX_INFO: 824 if (len < sizeof(rx_info)) 825 return -EINVAL; 826 rx_info.tfrcrx_x_recv = hc->rx_x_recv; 827 rx_info.tfrcrx_rtt = hc->rx_rtt; 828 rx_info.tfrcrx_p = tfrc_invert_loss_event_rate(hc->rx_pinv); 829 len = sizeof(rx_info); 830 val = &rx_info; 831 break; 832 default: 833 return -ENOPROTOOPT; 834 } 835 836 if (put_user(len, optlen) || copy_to_user(optval, val, len)) 837 return -EFAULT; 838 839 return 0; 840} 841 842struct ccid_operations ccid3_ops = { 843 .ccid_id = DCCPC_CCID3, 844 .ccid_name = "TCP-Friendly Rate Control", 845 .ccid_hc_tx_obj_size = sizeof(struct ccid3_hc_tx_sock), 846 .ccid_hc_tx_init = ccid3_hc_tx_init, 847 .ccid_hc_tx_exit = ccid3_hc_tx_exit, 848 .ccid_hc_tx_send_packet = ccid3_hc_tx_send_packet, 849 .ccid_hc_tx_packet_sent = ccid3_hc_tx_packet_sent, 850 .ccid_hc_tx_packet_recv = ccid3_hc_tx_packet_recv, 851 .ccid_hc_tx_parse_options = ccid3_hc_tx_parse_options, 852 .ccid_hc_rx_obj_size = sizeof(struct ccid3_hc_rx_sock), 853 .ccid_hc_rx_init = ccid3_hc_rx_init, 854 .ccid_hc_rx_exit = ccid3_hc_rx_exit, 855 .ccid_hc_rx_insert_options = ccid3_hc_rx_insert_options, 856 .ccid_hc_rx_packet_recv = ccid3_hc_rx_packet_recv, 857 .ccid_hc_rx_get_info = ccid3_hc_rx_get_info, 858 .ccid_hc_tx_get_info = ccid3_hc_tx_get_info, 859 .ccid_hc_rx_getsockopt = ccid3_hc_rx_getsockopt, 860 .ccid_hc_tx_getsockopt = ccid3_hc_tx_getsockopt, 861}; 862 863#ifdef CONFIG_IP_DCCP_CCID3_DEBUG 864module_param(ccid3_debug, bool, 0644); 865MODULE_PARM_DESC(ccid3_debug, "Enable CCID-3 debug messages"); 866#endif 867