1 /* 2 * Copyright (c) 2007 The University of Aberdeen, Scotland, UK 3 * Copyright (c) 2005-7 The University of Waikato, Hamilton, New Zealand. 4 * Copyright (c) 2005-7 Ian McDonald <ian.mcdonald@jandi.co.nz> 5 * 6 * An implementation of the DCCP protocol 7 * 8 * This code has been developed by the University of Waikato WAND 9 * research group. For further information please see http://www.wand.net.nz/ 10 * 11 * This code also uses code from Lulea University, rereleased as GPL by its 12 * authors: 13 * Copyright (c) 2003 Nils-Erik Mattsson, Joacim Haggmark, Magnus Erixzon 14 * 15 * Changes to meet Linux coding standards, to make it meet latest ccid3 draft 16 * and to make it work as a loadable module in the DCCP stack written by 17 * Arnaldo Carvalho de Melo <acme@conectiva.com.br>. 18 * 19 * Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@conectiva.com.br> 20 * 21 * This program is free software; you can redistribute it and/or modify 22 * it under the terms of the GNU General Public License as published by 23 * the Free Software Foundation; either version 2 of the License, or 24 * (at your option) any later version. 25 * 26 * This program is distributed in the hope that it will be useful, 27 * but WITHOUT ANY WARRANTY; without even the implied warranty of 28 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 29 * GNU General Public License for more details. 30 * 31 * You should have received a copy of the GNU General Public License 32 * along with this program; if not, write to the Free Software 33 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. 34 */ 35 #include "../dccp.h" 36 #include "ccid3.h" 37 38 #include <asm/unaligned.h> 39 40 #ifdef CONFIG_IP_DCCP_CCID3_DEBUG 41 static int ccid3_debug; 42 #define ccid3_pr_debug(format, a...) DCCP_PR_DEBUG(ccid3_debug, format, ##a) 43 #else 44 #define ccid3_pr_debug(format, a...) 45 #endif 46 47 /* 48 * Transmitter Half-Connection Routines 49 */ 50 #ifdef CONFIG_IP_DCCP_CCID3_DEBUG 51 static const char *ccid3_tx_state_name(enum ccid3_hc_tx_states state) 52 { 53 static const char *const ccid3_state_names[] = { 54 [TFRC_SSTATE_NO_SENT] = "NO_SENT", 55 [TFRC_SSTATE_NO_FBACK] = "NO_FBACK", 56 [TFRC_SSTATE_FBACK] = "FBACK", 57 [TFRC_SSTATE_TERM] = "TERM", 58 }; 59 60 return ccid3_state_names[state]; 61 } 62 #endif 63 64 static void ccid3_hc_tx_set_state(struct sock *sk, 65 enum ccid3_hc_tx_states state) 66 { 67 struct ccid3_hc_tx_sock *hc = ccid3_hc_tx_sk(sk); 68 enum ccid3_hc_tx_states oldstate = hc->tx_state; 69 70 ccid3_pr_debug("%s(%p) %-8.8s -> %s\n", 71 dccp_role(sk), sk, ccid3_tx_state_name(oldstate), 72 ccid3_tx_state_name(state)); 73 WARN_ON(state == oldstate); 74 hc->tx_state = state; 75 } 76 77 /* 78 * Compute the initial sending rate X_init in the manner of RFC 3390: 79 * 80 * X_init = min(4 * s, max(2 * s, 4380 bytes)) / RTT 81 * 82 * Note that RFC 3390 uses MSS, RFC 4342 refers to RFC 3390, and rfc3448bis 83 * (rev-02) clarifies the use of RFC 3390 with regard to the above formula. 84 * For consistency with other parts of the code, X_init is scaled by 2^6. 85 */ 86 static inline u64 rfc3390_initial_rate(struct sock *sk) 87 { 88 const struct ccid3_hc_tx_sock *hc = ccid3_hc_tx_sk(sk); 89 const __u32 w_init = clamp_t(__u32, 4380U, 2 * hc->tx_s, 4 * hc->tx_s); 90 91 return scaled_div(w_init << 6, hc->tx_rtt); 92 } 93 94 /* 95 * Recalculate t_ipi and delta (should be called whenever X changes) 96 */ 97 static void ccid3_update_send_interval(struct ccid3_hc_tx_sock *hc) 98 { 99 /* Calculate new t_ipi = s / X_inst (X_inst is in 64 * bytes/second) */ 100 hc->tx_t_ipi = scaled_div32(((u64)hc->tx_s) << 6, hc->tx_x); 101 102 /* Calculate new delta by delta = min(t_ipi / 2, t_gran / 2) */ 103 hc->tx_delta = min_t(u32, hc->tx_t_ipi / 2, TFRC_OPSYS_HALF_TIME_GRAN); 104 105 ccid3_pr_debug("t_ipi=%u, delta=%u, s=%u, X=%u\n", hc->tx_t_ipi, 106 hc->tx_delta, hc->tx_s, (unsigned)(hc->tx_x >> 6)); 107 } 108 109 static u32 ccid3_hc_tx_idle_rtt(struct ccid3_hc_tx_sock *hc, ktime_t now) 110 { 111 u32 delta = ktime_us_delta(now, hc->tx_t_last_win_count); 112 113 return delta / hc->tx_rtt; 114 } 115 116 /** 117 * ccid3_hc_tx_update_x - Update allowed sending rate X 118 * @stamp: most recent time if available - can be left NULL. 119 * This function tracks draft rfc3448bis, check there for latest details. 120 * 121 * Note: X and X_recv are both stored in units of 64 * bytes/second, to support 122 * fine-grained resolution of sending rates. This requires scaling by 2^6 123 * throughout the code. Only X_calc is unscaled (in bytes/second). 124 * 125 */ 126 static void ccid3_hc_tx_update_x(struct sock *sk, ktime_t *stamp) 127 { 128 struct ccid3_hc_tx_sock *hc = ccid3_hc_tx_sk(sk); 129 __u64 min_rate = 2 * hc->tx_x_recv; 130 const __u64 old_x = hc->tx_x; 131 ktime_t now = stamp ? *stamp : ktime_get_real(); 132 133 /* 134 * Handle IDLE periods: do not reduce below RFC3390 initial sending rate 135 * when idling [RFC 4342, 5.1]. Definition of idling is from rfc3448bis: 136 * a sender is idle if it has not sent anything over a 2-RTT-period. 137 * For consistency with X and X_recv, min_rate is also scaled by 2^6. 138 */ 139 if (ccid3_hc_tx_idle_rtt(hc, now) >= 2) { 140 min_rate = rfc3390_initial_rate(sk); 141 min_rate = max(min_rate, 2 * hc->tx_x_recv); 142 } 143 144 if (hc->tx_p > 0) { 145 146 hc->tx_x = min(((__u64)hc->tx_x_calc) << 6, min_rate); 147 hc->tx_x = max(hc->tx_x, (((__u64)hc->tx_s) << 6) / TFRC_T_MBI); 148 149 } else if (ktime_us_delta(now, hc->tx_t_ld) - (s64)hc->tx_rtt >= 0) { 150 151 hc->tx_x = min(2 * hc->tx_x, min_rate); 152 hc->tx_x = max(hc->tx_x, 153 scaled_div(((__u64)hc->tx_s) << 6, hc->tx_rtt)); 154 hc->tx_t_ld = now; 155 } 156 157 if (hc->tx_x != old_x) { 158 ccid3_pr_debug("X_prev=%u, X_now=%u, X_calc=%u, " 159 "X_recv=%u\n", (unsigned)(old_x >> 6), 160 (unsigned)(hc->tx_x >> 6), hc->tx_x_calc, 161 (unsigned)(hc->tx_x_recv >> 6)); 162 163 ccid3_update_send_interval(hc); 164 } 165 } 166 167 /* 168 * Track the mean packet size `s' (cf. RFC 4342, 5.3 and RFC 3448, 4.1) 169 * @len: DCCP packet payload size in bytes 170 */ 171 static inline void ccid3_hc_tx_update_s(struct ccid3_hc_tx_sock *hc, int len) 172 { 173 const u16 old_s = hc->tx_s; 174 175 hc->tx_s = tfrc_ewma(hc->tx_s, len, 9); 176 177 if (hc->tx_s != old_s) 178 ccid3_update_send_interval(hc); 179 } 180 181 /* 182 * Update Window Counter using the algorithm from [RFC 4342, 8.1]. 183 * As elsewhere, RTT > 0 is assumed by using dccp_sample_rtt(). 184 */ 185 static inline void ccid3_hc_tx_update_win_count(struct ccid3_hc_tx_sock *hc, 186 ktime_t now) 187 { 188 u32 delta = ktime_us_delta(now, hc->tx_t_last_win_count), 189 quarter_rtts = (4 * delta) / hc->tx_rtt; 190 191 if (quarter_rtts > 0) { 192 hc->tx_t_last_win_count = now; 193 hc->tx_last_win_count += min(quarter_rtts, 5U); 194 hc->tx_last_win_count &= 0xF; /* mod 16 */ 195 } 196 } 197 198 static void ccid3_hc_tx_no_feedback_timer(unsigned long data) 199 { 200 struct sock *sk = (struct sock *)data; 201 struct ccid3_hc_tx_sock *hc = ccid3_hc_tx_sk(sk); 202 unsigned long t_nfb = USEC_PER_SEC / 5; 203 204 bh_lock_sock(sk); 205 if (sock_owned_by_user(sk)) { 206 /* Try again later. */ 207 /* XXX: set some sensible MIB */ 208 goto restart_timer; 209 } 210 211 ccid3_pr_debug("%s(%p, state=%s) - entry\n", dccp_role(sk), sk, 212 ccid3_tx_state_name(hc->tx_state)); 213 214 if (hc->tx_state == TFRC_SSTATE_FBACK) 215 ccid3_hc_tx_set_state(sk, TFRC_SSTATE_NO_FBACK); 216 else if (hc->tx_state != TFRC_SSTATE_NO_FBACK) 217 goto out; 218 219 /* 220 * Determine new allowed sending rate X as per draft rfc3448bis-00, 4.4 221 */ 222 if (hc->tx_t_rto == 0 || /* no feedback received yet */ 223 hc->tx_p == 0) { 224 225 /* halve send rate directly */ 226 hc->tx_x = max(hc->tx_x / 2, 227 (((__u64)hc->tx_s) << 6) / TFRC_T_MBI); 228 ccid3_update_send_interval(hc); 229 } else { 230 /* 231 * Modify the cached value of X_recv 232 * 233 * If (X_calc > 2 * X_recv) 234 * X_recv = max(X_recv / 2, s / (2 * t_mbi)); 235 * Else 236 * X_recv = X_calc / 4; 237 * 238 * Note that X_recv is scaled by 2^6 while X_calc is not 239 */ 240 BUG_ON(hc->tx_p && !hc->tx_x_calc); 241 242 if (hc->tx_x_calc > (hc->tx_x_recv >> 5)) 243 hc->tx_x_recv = 244 max(hc->tx_x_recv / 2, 245 (((__u64)hc->tx_s) << 6) / (2*TFRC_T_MBI)); 246 else { 247 hc->tx_x_recv = hc->tx_x_calc; 248 hc->tx_x_recv <<= 4; 249 } 250 ccid3_hc_tx_update_x(sk, NULL); 251 } 252 ccid3_pr_debug("Reduced X to %llu/64 bytes/sec\n", 253 (unsigned long long)hc->tx_x); 254 255 /* 256 * Set new timeout for the nofeedback timer. 257 * See comments in packet_recv() regarding the value of t_RTO. 258 */ 259 if (unlikely(hc->tx_t_rto == 0)) /* no feedback yet */ 260 t_nfb = TFRC_INITIAL_TIMEOUT; 261 else 262 t_nfb = max(hc->tx_t_rto, 2 * hc->tx_t_ipi); 263 264 restart_timer: 265 sk_reset_timer(sk, &hc->tx_no_feedback_timer, 266 jiffies + usecs_to_jiffies(t_nfb)); 267 out: 268 bh_unlock_sock(sk); 269 sock_put(sk); 270 } 271 272 /* 273 * returns 274 * > 0: delay (in msecs) that should pass before actually sending 275 * = 0: can send immediately 276 * < 0: error condition; do not send packet 277 */ 278 static int ccid3_hc_tx_send_packet(struct sock *sk, struct sk_buff *skb) 279 { 280 struct dccp_sock *dp = dccp_sk(sk); 281 struct ccid3_hc_tx_sock *hc = ccid3_hc_tx_sk(sk); 282 ktime_t now = ktime_get_real(); 283 s64 delay; 284 285 /* 286 * This function is called only for Data and DataAck packets. Sending 287 * zero-sized Data(Ack)s is theoretically possible, but for congestion 288 * control this case is pathological - ignore it. 289 */ 290 if (unlikely(skb->len == 0)) 291 return -EBADMSG; 292 293 switch (hc->tx_state) { 294 case TFRC_SSTATE_NO_SENT: 295 sk_reset_timer(sk, &hc->tx_no_feedback_timer, (jiffies + 296 usecs_to_jiffies(TFRC_INITIAL_TIMEOUT))); 297 hc->tx_last_win_count = 0; 298 hc->tx_t_last_win_count = now; 299 300 /* Set t_0 for initial packet */ 301 hc->tx_t_nom = now; 302 303 hc->tx_s = skb->len; 304 305 /* 306 * Use initial RTT sample when available: recommended by erratum 307 * to RFC 4342. This implements the initialisation procedure of 308 * draft rfc3448bis, section 4.2. Remember, X is scaled by 2^6. 309 */ 310 if (dp->dccps_syn_rtt) { 311 ccid3_pr_debug("SYN RTT = %uus\n", dp->dccps_syn_rtt); 312 hc->tx_rtt = dp->dccps_syn_rtt; 313 hc->tx_x = rfc3390_initial_rate(sk); 314 hc->tx_t_ld = now; 315 } else { 316 /* 317 * Sender does not have RTT sample: 318 * - set fallback RTT (RFC 4340, 3.4) since a RTT value 319 * is needed in several parts (e.g. window counter); 320 * - set sending rate X_pps = 1pps as per RFC 3448, 4.2. 321 */ 322 hc->tx_rtt = DCCP_FALLBACK_RTT; 323 hc->tx_x = hc->tx_s; 324 hc->tx_x <<= 6; 325 } 326 ccid3_update_send_interval(hc); 327 328 ccid3_hc_tx_set_state(sk, TFRC_SSTATE_NO_FBACK); 329 break; 330 case TFRC_SSTATE_NO_FBACK: 331 case TFRC_SSTATE_FBACK: 332 delay = ktime_us_delta(hc->tx_t_nom, now); 333 ccid3_pr_debug("delay=%ld\n", (long)delay); 334 /* 335 * Scheduling of packet transmissions [RFC 3448, 4.6] 336 * 337 * if (t_now > t_nom - delta) 338 * // send the packet now 339 * else 340 * // send the packet in (t_nom - t_now) milliseconds. 341 */ 342 if (delay - (s64)hc->tx_delta >= 1000) 343 return (u32)delay / 1000L; 344 345 ccid3_hc_tx_update_win_count(hc, now); 346 break; 347 case TFRC_SSTATE_TERM: 348 DCCP_BUG("%s(%p) - Illegal state TERM", dccp_role(sk), sk); 349 return -EINVAL; 350 } 351 352 /* prepare to send now (add options etc.) */ 353 dp->dccps_hc_tx_insert_options = 1; 354 DCCP_SKB_CB(skb)->dccpd_ccval = hc->tx_last_win_count; 355 356 /* set the nominal send time for the next following packet */ 357 hc->tx_t_nom = ktime_add_us(hc->tx_t_nom, hc->tx_t_ipi); 358 return 0; 359 } 360 361 static void ccid3_hc_tx_packet_sent(struct sock *sk, int more, 362 unsigned int len) 363 { 364 struct ccid3_hc_tx_sock *hc = ccid3_hc_tx_sk(sk); 365 366 ccid3_hc_tx_update_s(hc, len); 367 368 if (tfrc_tx_hist_add(&hc->tx_hist, dccp_sk(sk)->dccps_gss)) 369 DCCP_CRIT("packet history - out of memory!"); 370 } 371 372 static void ccid3_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb) 373 { 374 struct ccid3_hc_tx_sock *hc = ccid3_hc_tx_sk(sk); 375 struct ccid3_options_received *opt_recv; 376 ktime_t now; 377 unsigned long t_nfb; 378 u32 pinv, r_sample; 379 380 /* we are only interested in ACKs */ 381 if (!(DCCP_SKB_CB(skb)->dccpd_type == DCCP_PKT_ACK || 382 DCCP_SKB_CB(skb)->dccpd_type == DCCP_PKT_DATAACK)) 383 return; 384 /* ... and only in the established state */ 385 if (hc->tx_state != TFRC_SSTATE_FBACK && 386 hc->tx_state != TFRC_SSTATE_NO_FBACK) 387 return; 388 389 opt_recv = &hc->tx_options_received; 390 now = ktime_get_real(); 391 392 /* Estimate RTT from history if ACK number is valid */ 393 r_sample = tfrc_tx_hist_rtt(hc->tx_hist, 394 DCCP_SKB_CB(skb)->dccpd_ack_seq, now); 395 if (r_sample == 0) { 396 DCCP_WARN("%s(%p): %s with bogus ACK-%llu\n", dccp_role(sk), sk, 397 dccp_packet_name(DCCP_SKB_CB(skb)->dccpd_type), 398 (unsigned long long)DCCP_SKB_CB(skb)->dccpd_ack_seq); 399 return; 400 } 401 402 /* Update receive rate in units of 64 * bytes/second */ 403 hc->tx_x_recv = opt_recv->ccid3or_receive_rate; 404 hc->tx_x_recv <<= 6; 405 406 /* Update loss event rate (which is scaled by 1e6) */ 407 pinv = opt_recv->ccid3or_loss_event_rate; 408 if (pinv == ~0U || pinv == 0) /* see RFC 4342, 8.5 */ 409 hc->tx_p = 0; 410 else /* can not exceed 100% */ 411 hc->tx_p = scaled_div(1, pinv); 412 /* 413 * Validate new RTT sample and update moving average 414 */ 415 r_sample = dccp_sample_rtt(sk, r_sample); 416 hc->tx_rtt = tfrc_ewma(hc->tx_rtt, r_sample, 9); 417 /* 418 * Update allowed sending rate X as per draft rfc3448bis-00, 4.2/3 419 */ 420 if (hc->tx_state == TFRC_SSTATE_NO_FBACK) { 421 ccid3_hc_tx_set_state(sk, TFRC_SSTATE_FBACK); 422 423 if (hc->tx_t_rto == 0) { 424 /* 425 * Initial feedback packet: Larger Initial Windows (4.2) 426 */ 427 hc->tx_x = rfc3390_initial_rate(sk); 428 hc->tx_t_ld = now; 429 430 ccid3_update_send_interval(hc); 431 432 goto done_computing_x; 433 } else if (hc->tx_p == 0) { 434 /* 435 * First feedback after nofeedback timer expiry (4.3) 436 */ 437 goto done_computing_x; 438 } 439 } 440 441 /* Update sending rate (step 4 of [RFC 3448, 4.3]) */ 442 if (hc->tx_p > 0) 443 hc->tx_x_calc = tfrc_calc_x(hc->tx_s, hc->tx_rtt, hc->tx_p); 444 ccid3_hc_tx_update_x(sk, &now); 445 446 done_computing_x: 447 ccid3_pr_debug("%s(%p), RTT=%uus (sample=%uus), s=%u, " 448 "p=%u, X_calc=%u, X_recv=%u, X=%u\n", 449 dccp_role(sk), sk, hc->tx_rtt, r_sample, 450 hc->tx_s, hc->tx_p, hc->tx_x_calc, 451 (unsigned)(hc->tx_x_recv >> 6), 452 (unsigned)(hc->tx_x >> 6)); 453 454 /* unschedule no feedback timer */ 455 sk_stop_timer(sk, &hc->tx_no_feedback_timer); 456 457 /* 458 * As we have calculated new ipi, delta, t_nom it is possible 459 * that we now can send a packet, so wake up dccp_wait_for_ccid 460 */ 461 sk->sk_write_space(sk); 462 463 /* 464 * Update timeout interval for the nofeedback timer. 465 * We use a configuration option to increase the lower bound. 466 * This can help avoid triggering the nofeedback timer too 467 * often ('spinning') on LANs with small RTTs. 468 */ 469 hc->tx_t_rto = max_t(u32, 4 * hc->tx_rtt, (CONFIG_IP_DCCP_CCID3_RTO * 470 (USEC_PER_SEC / 1000))); 471 /* 472 * Schedule no feedback timer to expire in 473 * max(t_RTO, 2 * s/X) = max(t_RTO, 2 * t_ipi) 474 */ 475 t_nfb = max(hc->tx_t_rto, 2 * hc->tx_t_ipi); 476 477 ccid3_pr_debug("%s(%p), Scheduled no feedback timer to " 478 "expire in %lu jiffies (%luus)\n", 479 dccp_role(sk), sk, usecs_to_jiffies(t_nfb), t_nfb); 480 481 sk_reset_timer(sk, &hc->tx_no_feedback_timer, 482 jiffies + usecs_to_jiffies(t_nfb)); 483 } 484 485 static int ccid3_hc_tx_parse_options(struct sock *sk, unsigned char option, 486 unsigned char len, u16 idx, 487 unsigned char *value) 488 { 489 int rc = 0; 490 const struct dccp_sock *dp = dccp_sk(sk); 491 struct ccid3_hc_tx_sock *hc = ccid3_hc_tx_sk(sk); 492 struct ccid3_options_received *opt_recv; 493 __be32 opt_val; 494 495 opt_recv = &hc->tx_options_received; 496 497 if (opt_recv->ccid3or_seqno != dp->dccps_gsr) { 498 opt_recv->ccid3or_seqno = dp->dccps_gsr; 499 opt_recv->ccid3or_loss_event_rate = ~0; 500 opt_recv->ccid3or_loss_intervals_idx = 0; 501 opt_recv->ccid3or_loss_intervals_len = 0; 502 opt_recv->ccid3or_receive_rate = 0; 503 } 504 505 switch (option) { 506 case TFRC_OPT_LOSS_EVENT_RATE: 507 if (unlikely(len != 4)) { 508 DCCP_WARN("%s(%p), invalid len %d " 509 "for TFRC_OPT_LOSS_EVENT_RATE\n", 510 dccp_role(sk), sk, len); 511 rc = -EINVAL; 512 } else { 513 opt_val = get_unaligned((__be32 *)value); 514 opt_recv->ccid3or_loss_event_rate = ntohl(opt_val); 515 ccid3_pr_debug("%s(%p), LOSS_EVENT_RATE=%u\n", 516 dccp_role(sk), sk, 517 opt_recv->ccid3or_loss_event_rate); 518 } 519 break; 520 case TFRC_OPT_LOSS_INTERVALS: 521 opt_recv->ccid3or_loss_intervals_idx = idx; 522 opt_recv->ccid3or_loss_intervals_len = len; 523 ccid3_pr_debug("%s(%p), LOSS_INTERVALS=(%u, %u)\n", 524 dccp_role(sk), sk, 525 opt_recv->ccid3or_loss_intervals_idx, 526 opt_recv->ccid3or_loss_intervals_len); 527 break; 528 case TFRC_OPT_RECEIVE_RATE: 529 if (unlikely(len != 4)) { 530 DCCP_WARN("%s(%p), invalid len %d " 531 "for TFRC_OPT_RECEIVE_RATE\n", 532 dccp_role(sk), sk, len); 533 rc = -EINVAL; 534 } else { 535 opt_val = get_unaligned((__be32 *)value); 536 opt_recv->ccid3or_receive_rate = ntohl(opt_val); 537 ccid3_pr_debug("%s(%p), RECEIVE_RATE=%u\n", 538 dccp_role(sk), sk, 539 opt_recv->ccid3or_receive_rate); 540 } 541 break; 542 } 543 544 return rc; 545 } 546 547 static int ccid3_hc_tx_init(struct ccid *ccid, struct sock *sk) 548 { 549 struct ccid3_hc_tx_sock *hc = ccid_priv(ccid); 550 551 hc->tx_state = TFRC_SSTATE_NO_SENT; 552 hc->tx_hist = NULL; 553 setup_timer(&hc->tx_no_feedback_timer, 554 ccid3_hc_tx_no_feedback_timer, (unsigned long)sk); 555 return 0; 556 } 557 558 static void ccid3_hc_tx_exit(struct sock *sk) 559 { 560 struct ccid3_hc_tx_sock *hc = ccid3_hc_tx_sk(sk); 561 562 ccid3_hc_tx_set_state(sk, TFRC_SSTATE_TERM); 563 sk_stop_timer(sk, &hc->tx_no_feedback_timer); 564 565 tfrc_tx_hist_purge(&hc->tx_hist); 566 } 567 568 static void ccid3_hc_tx_get_info(struct sock *sk, struct tcp_info *info) 569 { 570 struct ccid3_hc_tx_sock *hc; 571 572 /* Listen socks doesn't have a private CCID block */ 573 if (sk->sk_state == DCCP_LISTEN) 574 return; 575 576 hc = ccid3_hc_tx_sk(sk); 577 info->tcpi_rto = hc->tx_t_rto; 578 info->tcpi_rtt = hc->tx_rtt; 579 } 580 581 static int ccid3_hc_tx_getsockopt(struct sock *sk, const int optname, int len, 582 u32 __user *optval, int __user *optlen) 583 { 584 const struct ccid3_hc_tx_sock *hc; 585 const void *val; 586 587 /* Listen socks doesn't have a private CCID block */ 588 if (sk->sk_state == DCCP_LISTEN) 589 return -EINVAL; 590 591 hc = ccid3_hc_tx_sk(sk); 592 switch (optname) { 593 case DCCP_SOCKOPT_CCID_TX_INFO: 594 if (len < sizeof(hc->tx_tfrc)) 595 return -EINVAL; 596 len = sizeof(hc->tx_tfrc); 597 val = &hc->tx_tfrc; 598 break; 599 default: 600 return -ENOPROTOOPT; 601 } 602 603 if (put_user(len, optlen) || copy_to_user(optval, val, len)) 604 return -EFAULT; 605 606 return 0; 607 } 608 609 /* 610 * Receiver Half-Connection Routines 611 */ 612 613 /* CCID3 feedback types */ 614 enum ccid3_fback_type { 615 CCID3_FBACK_NONE = 0, 616 CCID3_FBACK_INITIAL, 617 CCID3_FBACK_PERIODIC, 618 CCID3_FBACK_PARAM_CHANGE 619 }; 620 621 #ifdef CONFIG_IP_DCCP_CCID3_DEBUG 622 static const char *ccid3_rx_state_name(enum ccid3_hc_rx_states state) 623 { 624 static const char *const ccid3_rx_state_names[] = { 625 [TFRC_RSTATE_NO_DATA] = "NO_DATA", 626 [TFRC_RSTATE_DATA] = "DATA", 627 [TFRC_RSTATE_TERM] = "TERM", 628 }; 629 630 return ccid3_rx_state_names[state]; 631 } 632 #endif 633 634 static void ccid3_hc_rx_set_state(struct sock *sk, 635 enum ccid3_hc_rx_states state) 636 { 637 struct ccid3_hc_rx_sock *hc = ccid3_hc_rx_sk(sk); 638 enum ccid3_hc_rx_states oldstate = hc->rx_state; 639 640 ccid3_pr_debug("%s(%p) %-8.8s -> %s\n", 641 dccp_role(sk), sk, ccid3_rx_state_name(oldstate), 642 ccid3_rx_state_name(state)); 643 WARN_ON(state == oldstate); 644 hc->rx_state = state; 645 } 646 647 static void ccid3_hc_rx_send_feedback(struct sock *sk, 648 const struct sk_buff *skb, 649 enum ccid3_fback_type fbtype) 650 { 651 struct ccid3_hc_rx_sock *hc = ccid3_hc_rx_sk(sk); 652 struct dccp_sock *dp = dccp_sk(sk); 653 ktime_t now; 654 s64 delta = 0; 655 656 if (unlikely(hc->rx_state == TFRC_RSTATE_TERM)) 657 return; 658 659 now = ktime_get_real(); 660 661 switch (fbtype) { 662 case CCID3_FBACK_INITIAL: 663 hc->rx_x_recv = 0; 664 hc->rx_pinv = ~0U; /* see RFC 4342, 8.5 */ 665 break; 666 case CCID3_FBACK_PARAM_CHANGE: 667 /* 668 * When parameters change (new loss or p > p_prev), we do not 669 * have a reliable estimate for R_m of [RFC 3448, 6.2] and so 670 * need to reuse the previous value of X_recv. However, when 671 * X_recv was 0 (due to early loss), this would kill X down to 672 * s/t_mbi (i.e. one packet in 64 seconds). 673 * To avoid such drastic reduction, we approximate X_recv as 674 * the number of bytes since last feedback. 675 * This is a safe fallback, since X is bounded above by X_calc. 676 */ 677 if (hc->rx_x_recv > 0) 678 break; 679 /* fall through */ 680 case CCID3_FBACK_PERIODIC: 681 delta = ktime_us_delta(now, hc->rx_tstamp_last_feedback); 682 if (delta <= 0) 683 DCCP_BUG("delta (%ld) <= 0", (long)delta); 684 else 685 hc->rx_x_recv = scaled_div32(hc->rx_bytes_recv, delta); 686 break; 687 default: 688 return; 689 } 690 691 ccid3_pr_debug("Interval %ldusec, X_recv=%u, 1/p=%u\n", (long)delta, 692 hc->rx_x_recv, hc->rx_pinv); 693 694 hc->rx_tstamp_last_feedback = now; 695 hc->rx_last_counter = dccp_hdr(skb)->dccph_ccval; 696 hc->rx_bytes_recv = 0; 697 698 dp->dccps_hc_rx_insert_options = 1; 699 dccp_send_ack(sk); 700 } 701 702 static int ccid3_hc_rx_insert_options(struct sock *sk, struct sk_buff *skb) 703 { 704 const struct ccid3_hc_rx_sock *hc; 705 __be32 x_recv, pinv; 706 707 if (!(sk->sk_state == DCCP_OPEN || sk->sk_state == DCCP_PARTOPEN)) 708 return 0; 709 710 hc = ccid3_hc_rx_sk(sk); 711 712 if (dccp_packet_without_ack(skb)) 713 return 0; 714 715 x_recv = htonl(hc->rx_x_recv); 716 pinv = htonl(hc->rx_pinv); 717 718 if (dccp_insert_option(sk, skb, TFRC_OPT_LOSS_EVENT_RATE, 719 &pinv, sizeof(pinv)) || 720 dccp_insert_option(sk, skb, TFRC_OPT_RECEIVE_RATE, 721 &x_recv, sizeof(x_recv))) 722 return -1; 723 724 return 0; 725 } 726 727 /** 728 * ccid3_first_li - Implements [RFC 5348, 6.3.1] 729 * 730 * Determine the length of the first loss interval via inverse lookup. 731 * Assume that X_recv can be computed by the throughput equation 732 * s 733 * X_recv = -------- 734 * R * fval 735 * Find some p such that f(p) = fval; return 1/p (scaled). 736 */ 737 static u32 ccid3_first_li(struct sock *sk) 738 { 739 struct ccid3_hc_rx_sock *hc = ccid3_hc_rx_sk(sk); 740 u32 x_recv, p, delta; 741 u64 fval; 742 743 if (hc->rx_rtt == 0) { 744 DCCP_WARN("No RTT estimate available, using fallback RTT\n"); 745 hc->rx_rtt = DCCP_FALLBACK_RTT; 746 } 747 748 delta = ktime_to_us(net_timedelta(hc->rx_tstamp_last_feedback)); 749 x_recv = scaled_div32(hc->rx_bytes_recv, delta); 750 if (x_recv == 0) { /* would also trigger divide-by-zero */ 751 DCCP_WARN("X_recv==0\n"); 752 if ((x_recv = hc->rx_x_recv) == 0) { 753 DCCP_BUG("stored value of X_recv is zero"); 754 return ~0U; 755 } 756 } 757 758 fval = scaled_div(hc->rx_s, hc->rx_rtt); 759 fval = scaled_div32(fval, x_recv); 760 p = tfrc_calc_x_reverse_lookup(fval); 761 762 ccid3_pr_debug("%s(%p), receive rate=%u bytes/s, implied " 763 "loss rate=%u\n", dccp_role(sk), sk, x_recv, p); 764 765 return p == 0 ? ~0U : scaled_div(1, p); 766 } 767 768 static void ccid3_hc_rx_packet_recv(struct sock *sk, struct sk_buff *skb) 769 { 770 struct ccid3_hc_rx_sock *hc = ccid3_hc_rx_sk(sk); 771 enum ccid3_fback_type do_feedback = CCID3_FBACK_NONE; 772 const u64 ndp = dccp_sk(sk)->dccps_options_received.dccpor_ndp; 773 const bool is_data_packet = dccp_data_packet(skb); 774 775 if (unlikely(hc->rx_state == TFRC_RSTATE_NO_DATA)) { 776 if (is_data_packet) { 777 const u32 payload = skb->len - dccp_hdr(skb)->dccph_doff * 4; 778 do_feedback = CCID3_FBACK_INITIAL; 779 ccid3_hc_rx_set_state(sk, TFRC_RSTATE_DATA); 780 hc->rx_s = payload; 781 /* 782 * Not necessary to update rx_bytes_recv here, 783 * since X_recv = 0 for the first feedback packet (cf. 784 * RFC 3448, 6.3) -- gerrit 785 */ 786 } 787 goto update_records; 788 } 789 790 if (tfrc_rx_hist_duplicate(&hc->rx_hist, skb)) 791 return; /* done receiving */ 792 793 if (is_data_packet) { 794 const u32 payload = skb->len - dccp_hdr(skb)->dccph_doff * 4; 795 /* 796 * Update moving-average of s and the sum of received payload bytes 797 */ 798 hc->rx_s = tfrc_ewma(hc->rx_s, payload, 9); 799 hc->rx_bytes_recv += payload; 800 } 801 802 /* 803 * Perform loss detection and handle pending losses 804 */ 805 if (tfrc_rx_handle_loss(&hc->rx_hist, &hc->rx_li_hist, 806 skb, ndp, ccid3_first_li, sk)) { 807 do_feedback = CCID3_FBACK_PARAM_CHANGE; 808 goto done_receiving; 809 } 810 811 if (tfrc_rx_hist_loss_pending(&hc->rx_hist)) 812 return; /* done receiving */ 813 814 /* 815 * Handle data packets: RTT sampling and monitoring p 816 */ 817 if (unlikely(!is_data_packet)) 818 goto update_records; 819 820 if (!tfrc_lh_is_initialised(&hc->rx_li_hist)) { 821 const u32 sample = tfrc_rx_hist_sample_rtt(&hc->rx_hist, skb); 822 /* 823 * Empty loss history: no loss so far, hence p stays 0. 824 * Sample RTT values, since an RTT estimate is required for the 825 * computation of p when the first loss occurs; RFC 3448, 6.3.1. 826 */ 827 if (sample != 0) 828 hc->rx_rtt = tfrc_ewma(hc->rx_rtt, sample, 9); 829 830 } else if (tfrc_lh_update_i_mean(&hc->rx_li_hist, skb)) { 831 /* 832 * Step (3) of [RFC 3448, 6.1]: Recompute I_mean and, if I_mean 833 * has decreased (resp. p has increased), send feedback now. 834 */ 835 do_feedback = CCID3_FBACK_PARAM_CHANGE; 836 } 837 838 /* 839 * Check if the periodic once-per-RTT feedback is due; RFC 4342, 10.3 840 */ 841 if (SUB16(dccp_hdr(skb)->dccph_ccval, hc->rx_last_counter) > 3) 842 do_feedback = CCID3_FBACK_PERIODIC; 843 844 update_records: 845 tfrc_rx_hist_add_packet(&hc->rx_hist, skb, ndp); 846 847 done_receiving: 848 if (do_feedback) 849 ccid3_hc_rx_send_feedback(sk, skb, do_feedback); 850 } 851 852 static int ccid3_hc_rx_init(struct ccid *ccid, struct sock *sk) 853 { 854 struct ccid3_hc_rx_sock *hc = ccid_priv(ccid); 855 856 hc->rx_state = TFRC_RSTATE_NO_DATA; 857 tfrc_lh_init(&hc->rx_li_hist); 858 return tfrc_rx_hist_alloc(&hc->rx_hist); 859 } 860 861 static void ccid3_hc_rx_exit(struct sock *sk) 862 { 863 struct ccid3_hc_rx_sock *hc = ccid3_hc_rx_sk(sk); 864 865 ccid3_hc_rx_set_state(sk, TFRC_RSTATE_TERM); 866 867 tfrc_rx_hist_purge(&hc->rx_hist); 868 tfrc_lh_cleanup(&hc->rx_li_hist); 869 } 870 871 static void ccid3_hc_rx_get_info(struct sock *sk, struct tcp_info *info) 872 { 873 const struct ccid3_hc_rx_sock *hc; 874 875 /* Listen socks doesn't have a private CCID block */ 876 if (sk->sk_state == DCCP_LISTEN) 877 return; 878 879 hc = ccid3_hc_rx_sk(sk); 880 info->tcpi_ca_state = hc->rx_state; 881 info->tcpi_options |= TCPI_OPT_TIMESTAMPS; 882 info->tcpi_rcv_rtt = hc->rx_rtt; 883 } 884 885 static int ccid3_hc_rx_getsockopt(struct sock *sk, const int optname, int len, 886 u32 __user *optval, int __user *optlen) 887 { 888 const struct ccid3_hc_rx_sock *hc; 889 struct tfrc_rx_info rx_info; 890 const void *val; 891 892 /* Listen socks doesn't have a private CCID block */ 893 if (sk->sk_state == DCCP_LISTEN) 894 return -EINVAL; 895 896 hc = ccid3_hc_rx_sk(sk); 897 switch (optname) { 898 case DCCP_SOCKOPT_CCID_RX_INFO: 899 if (len < sizeof(rx_info)) 900 return -EINVAL; 901 rx_info.tfrcrx_x_recv = hc->rx_x_recv; 902 rx_info.tfrcrx_rtt = hc->rx_rtt; 903 rx_info.tfrcrx_p = hc->rx_pinv == 0 ? ~0U : 904 scaled_div(1, hc->rx_pinv); 905 len = sizeof(rx_info); 906 val = &rx_info; 907 break; 908 default: 909 return -ENOPROTOOPT; 910 } 911 912 if (put_user(len, optlen) || copy_to_user(optval, val, len)) 913 return -EFAULT; 914 915 return 0; 916 } 917 918 struct ccid_operations ccid3_ops = { 919 .ccid_id = DCCPC_CCID3, 920 .ccid_name = "TCP-Friendly Rate Control", 921 .ccid_hc_tx_obj_size = sizeof(struct ccid3_hc_tx_sock), 922 .ccid_hc_tx_init = ccid3_hc_tx_init, 923 .ccid_hc_tx_exit = ccid3_hc_tx_exit, 924 .ccid_hc_tx_send_packet = ccid3_hc_tx_send_packet, 925 .ccid_hc_tx_packet_sent = ccid3_hc_tx_packet_sent, 926 .ccid_hc_tx_packet_recv = ccid3_hc_tx_packet_recv, 927 .ccid_hc_tx_parse_options = ccid3_hc_tx_parse_options, 928 .ccid_hc_rx_obj_size = sizeof(struct ccid3_hc_rx_sock), 929 .ccid_hc_rx_init = ccid3_hc_rx_init, 930 .ccid_hc_rx_exit = ccid3_hc_rx_exit, 931 .ccid_hc_rx_insert_options = ccid3_hc_rx_insert_options, 932 .ccid_hc_rx_packet_recv = ccid3_hc_rx_packet_recv, 933 .ccid_hc_rx_get_info = ccid3_hc_rx_get_info, 934 .ccid_hc_tx_get_info = ccid3_hc_tx_get_info, 935 .ccid_hc_rx_getsockopt = ccid3_hc_rx_getsockopt, 936 .ccid_hc_tx_getsockopt = ccid3_hc_tx_getsockopt, 937 }; 938 939 #ifdef CONFIG_IP_DCCP_CCID3_DEBUG 940 module_param(ccid3_debug, bool, 0644); 941 MODULE_PARM_DESC(ccid3_debug, "Enable CCID-3 debug messages"); 942 #endif 943