1 /* 2 * net/dccp/ccids/ccid3.c 3 * 4 * Copyright (c) 2007 The University of Aberdeen, Scotland, UK 5 * Copyright (c) 2005-7 The University of Waikato, Hamilton, New Zealand. 6 * Copyright (c) 2005-7 Ian McDonald <ian.mcdonald@jandi.co.nz> 7 * 8 * An implementation of the DCCP protocol 9 * 10 * This code has been developed by the University of Waikato WAND 11 * research group. For further information please see http://www.wand.net.nz/ 12 * 13 * This code also uses code from Lulea University, rereleased as GPL by its 14 * authors: 15 * Copyright (c) 2003 Nils-Erik Mattsson, Joacim Haggmark, Magnus Erixzon 16 * 17 * Changes to meet Linux coding standards, to make it meet latest ccid3 draft 18 * and to make it work as a loadable module in the DCCP stack written by 19 * Arnaldo Carvalho de Melo <acme@conectiva.com.br>. 20 * 21 * Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@conectiva.com.br> 22 * 23 * This program is free software; you can redistribute it and/or modify 24 * it under the terms of the GNU General Public License as published by 25 * the Free Software Foundation; either version 2 of the License, or 26 * (at your option) any later version. 27 * 28 * This program is distributed in the hope that it will be useful, 29 * but WITHOUT ANY WARRANTY; without even the implied warranty of 30 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 31 * GNU General Public License for more details. 32 * 33 * You should have received a copy of the GNU General Public License 34 * along with this program; if not, write to the Free Software 35 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. 36 */ 37 #include "../dccp.h" 38 #include "ccid3.h" 39 40 #include <asm/unaligned.h> 41 42 #ifdef CONFIG_IP_DCCP_CCID3_DEBUG 43 static int ccid3_debug; 44 #define ccid3_pr_debug(format, a...) DCCP_PR_DEBUG(ccid3_debug, format, ##a) 45 #else 46 #define ccid3_pr_debug(format, a...) 47 #endif 48 49 /* 50 * Transmitter Half-Connection Routines 51 */ 52 #ifdef CONFIG_IP_DCCP_CCID3_DEBUG 53 static const char *ccid3_tx_state_name(enum ccid3_hc_tx_states state) 54 { 55 static char *ccid3_state_names[] = { 56 [TFRC_SSTATE_NO_SENT] = "NO_SENT", 57 [TFRC_SSTATE_NO_FBACK] = "NO_FBACK", 58 [TFRC_SSTATE_FBACK] = "FBACK", 59 [TFRC_SSTATE_TERM] = "TERM", 60 }; 61 62 return ccid3_state_names[state]; 63 } 64 #endif 65 66 static void ccid3_hc_tx_set_state(struct sock *sk, 67 enum ccid3_hc_tx_states state) 68 { 69 struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk); 70 enum ccid3_hc_tx_states oldstate = hctx->ccid3hctx_state; 71 72 ccid3_pr_debug("%s(%p) %-8.8s -> %s\n", 73 dccp_role(sk), sk, ccid3_tx_state_name(oldstate), 74 ccid3_tx_state_name(state)); 75 WARN_ON(state == oldstate); 76 hctx->ccid3hctx_state = state; 77 } 78 79 /* 80 * Compute the initial sending rate X_init in the manner of RFC 3390: 81 * 82 * X_init = min(4 * s, max(2 * s, 4380 bytes)) / RTT 83 * 84 * Note that RFC 3390 uses MSS, RFC 4342 refers to RFC 3390, and rfc3448bis 85 * (rev-02) clarifies the use of RFC 3390 with regard to the above formula. 86 * For consistency with other parts of the code, X_init is scaled by 2^6. 87 */ 88 static inline u64 rfc3390_initial_rate(struct sock *sk) 89 { 90 const struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk); 91 const __u32 w_init = clamp_t(__u32, 4380U, 92 2 * hctx->ccid3hctx_s, 4 * hctx->ccid3hctx_s); 93 94 return scaled_div(w_init << 6, hctx->ccid3hctx_rtt); 95 } 96 97 /* 98 * Recalculate t_ipi and delta (should be called whenever X changes) 99 */ 100 static void ccid3_update_send_interval(struct ccid3_hc_tx_sock *hctx) 101 { 102 /* Calculate new t_ipi = s / X_inst (X_inst is in 64 * bytes/second) */ 103 hctx->ccid3hctx_t_ipi = scaled_div32(((u64)hctx->ccid3hctx_s) << 6, 104 hctx->ccid3hctx_x); 105 106 /* Calculate new delta by delta = min(t_ipi / 2, t_gran / 2) */ 107 hctx->ccid3hctx_delta = min_t(u32, hctx->ccid3hctx_t_ipi / 2, 108 TFRC_OPSYS_HALF_TIME_GRAN); 109 110 ccid3_pr_debug("t_ipi=%u, delta=%u, s=%u, X=%u\n", 111 hctx->ccid3hctx_t_ipi, hctx->ccid3hctx_delta, 112 hctx->ccid3hctx_s, (unsigned)(hctx->ccid3hctx_x >> 6)); 113 114 } 115 116 static u32 ccid3_hc_tx_idle_rtt(struct ccid3_hc_tx_sock *hctx, ktime_t now) 117 { 118 u32 delta = ktime_us_delta(now, hctx->ccid3hctx_t_last_win_count); 119 120 return delta / hctx->ccid3hctx_rtt; 121 } 122 123 /** 124 * ccid3_hc_tx_update_x - Update allowed sending rate X 125 * @stamp: most recent time if available - can be left NULL. 126 * This function tracks draft rfc3448bis, check there for latest details. 127 * 128 * Note: X and X_recv are both stored in units of 64 * bytes/second, to support 129 * fine-grained resolution of sending rates. This requires scaling by 2^6 130 * throughout the code. Only X_calc is unscaled (in bytes/second). 131 * 132 */ 133 static void ccid3_hc_tx_update_x(struct sock *sk, ktime_t *stamp) 134 { 135 struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk); 136 __u64 min_rate = 2 * hctx->ccid3hctx_x_recv; 137 const __u64 old_x = hctx->ccid3hctx_x; 138 ktime_t now = stamp ? *stamp : ktime_get_real(); 139 140 /* 141 * Handle IDLE periods: do not reduce below RFC3390 initial sending rate 142 * when idling [RFC 4342, 5.1]. Definition of idling is from rfc3448bis: 143 * a sender is idle if it has not sent anything over a 2-RTT-period. 144 * For consistency with X and X_recv, min_rate is also scaled by 2^6. 145 */ 146 if (ccid3_hc_tx_idle_rtt(hctx, now) >= 2) { 147 min_rate = rfc3390_initial_rate(sk); 148 min_rate = max(min_rate, 2 * hctx->ccid3hctx_x_recv); 149 } 150 151 if (hctx->ccid3hctx_p > 0) { 152 153 hctx->ccid3hctx_x = min(((__u64)hctx->ccid3hctx_x_calc) << 6, 154 min_rate); 155 hctx->ccid3hctx_x = max(hctx->ccid3hctx_x, 156 (((__u64)hctx->ccid3hctx_s) << 6) / 157 TFRC_T_MBI); 158 159 } else if (ktime_us_delta(now, hctx->ccid3hctx_t_ld) 160 - (s64)hctx->ccid3hctx_rtt >= 0) { 161 162 hctx->ccid3hctx_x = min(2 * hctx->ccid3hctx_x, min_rate); 163 hctx->ccid3hctx_x = max(hctx->ccid3hctx_x, 164 scaled_div(((__u64)hctx->ccid3hctx_s) << 6, 165 hctx->ccid3hctx_rtt)); 166 hctx->ccid3hctx_t_ld = now; 167 } 168 169 if (hctx->ccid3hctx_x != old_x) { 170 ccid3_pr_debug("X_prev=%u, X_now=%u, X_calc=%u, " 171 "X_recv=%u\n", (unsigned)(old_x >> 6), 172 (unsigned)(hctx->ccid3hctx_x >> 6), 173 hctx->ccid3hctx_x_calc, 174 (unsigned)(hctx->ccid3hctx_x_recv >> 6)); 175 176 ccid3_update_send_interval(hctx); 177 } 178 } 179 180 /* 181 * Track the mean packet size `s' (cf. RFC 4342, 5.3 and RFC 3448, 4.1) 182 * @len: DCCP packet payload size in bytes 183 */ 184 static inline void ccid3_hc_tx_update_s(struct ccid3_hc_tx_sock *hctx, int len) 185 { 186 const u16 old_s = hctx->ccid3hctx_s; 187 188 hctx->ccid3hctx_s = tfrc_ewma(hctx->ccid3hctx_s, len, 9); 189 190 if (hctx->ccid3hctx_s != old_s) 191 ccid3_update_send_interval(hctx); 192 } 193 194 /* 195 * Update Window Counter using the algorithm from [RFC 4342, 8.1]. 196 * As elsewhere, RTT > 0 is assumed by using dccp_sample_rtt(). 197 */ 198 static inline void ccid3_hc_tx_update_win_count(struct ccid3_hc_tx_sock *hctx, 199 ktime_t now) 200 { 201 u32 delta = ktime_us_delta(now, hctx->ccid3hctx_t_last_win_count), 202 quarter_rtts = (4 * delta) / hctx->ccid3hctx_rtt; 203 204 if (quarter_rtts > 0) { 205 hctx->ccid3hctx_t_last_win_count = now; 206 hctx->ccid3hctx_last_win_count += min(quarter_rtts, 5U); 207 hctx->ccid3hctx_last_win_count &= 0xF; /* mod 16 */ 208 } 209 } 210 211 static void ccid3_hc_tx_no_feedback_timer(unsigned long data) 212 { 213 struct sock *sk = (struct sock *)data; 214 struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk); 215 unsigned long t_nfb = USEC_PER_SEC / 5; 216 217 bh_lock_sock(sk); 218 if (sock_owned_by_user(sk)) { 219 /* Try again later. */ 220 /* XXX: set some sensible MIB */ 221 goto restart_timer; 222 } 223 224 ccid3_pr_debug("%s(%p, state=%s) - entry \n", dccp_role(sk), sk, 225 ccid3_tx_state_name(hctx->ccid3hctx_state)); 226 227 if (hctx->ccid3hctx_state == TFRC_SSTATE_FBACK) 228 ccid3_hc_tx_set_state(sk, TFRC_SSTATE_NO_FBACK); 229 else if (hctx->ccid3hctx_state != TFRC_SSTATE_NO_FBACK) 230 goto out; 231 232 /* 233 * Determine new allowed sending rate X as per draft rfc3448bis-00, 4.4 234 */ 235 if (hctx->ccid3hctx_t_rto == 0 || /* no feedback received yet */ 236 hctx->ccid3hctx_p == 0) { 237 238 /* halve send rate directly */ 239 hctx->ccid3hctx_x = max(hctx->ccid3hctx_x / 2, 240 (((__u64)hctx->ccid3hctx_s) << 6) / 241 TFRC_T_MBI); 242 ccid3_update_send_interval(hctx); 243 } else { 244 /* 245 * Modify the cached value of X_recv 246 * 247 * If (X_calc > 2 * X_recv) 248 * X_recv = max(X_recv / 2, s / (2 * t_mbi)); 249 * Else 250 * X_recv = X_calc / 4; 251 * 252 * Note that X_recv is scaled by 2^6 while X_calc is not 253 */ 254 BUG_ON(hctx->ccid3hctx_p && !hctx->ccid3hctx_x_calc); 255 256 if (hctx->ccid3hctx_x_calc > (hctx->ccid3hctx_x_recv >> 5)) 257 hctx->ccid3hctx_x_recv = 258 max(hctx->ccid3hctx_x_recv / 2, 259 (((__u64)hctx->ccid3hctx_s) << 6) / 260 (2 * TFRC_T_MBI)); 261 else { 262 hctx->ccid3hctx_x_recv = hctx->ccid3hctx_x_calc; 263 hctx->ccid3hctx_x_recv <<= 4; 264 } 265 ccid3_hc_tx_update_x(sk, NULL); 266 } 267 ccid3_pr_debug("Reduced X to %llu/64 bytes/sec\n", 268 (unsigned long long)hctx->ccid3hctx_x); 269 270 /* 271 * Set new timeout for the nofeedback timer. 272 * See comments in packet_recv() regarding the value of t_RTO. 273 */ 274 if (unlikely(hctx->ccid3hctx_t_rto == 0)) /* no feedback yet */ 275 t_nfb = TFRC_INITIAL_TIMEOUT; 276 else 277 t_nfb = max(hctx->ccid3hctx_t_rto, 2 * hctx->ccid3hctx_t_ipi); 278 279 restart_timer: 280 sk_reset_timer(sk, &hctx->ccid3hctx_no_feedback_timer, 281 jiffies + usecs_to_jiffies(t_nfb)); 282 out: 283 bh_unlock_sock(sk); 284 sock_put(sk); 285 } 286 287 /* 288 * returns 289 * > 0: delay (in msecs) that should pass before actually sending 290 * = 0: can send immediately 291 * < 0: error condition; do not send packet 292 */ 293 static int ccid3_hc_tx_send_packet(struct sock *sk, struct sk_buff *skb) 294 { 295 struct dccp_sock *dp = dccp_sk(sk); 296 struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk); 297 ktime_t now = ktime_get_real(); 298 s64 delay; 299 300 /* 301 * This function is called only for Data and DataAck packets. Sending 302 * zero-sized Data(Ack)s is theoretically possible, but for congestion 303 * control this case is pathological - ignore it. 304 */ 305 if (unlikely(skb->len == 0)) 306 return -EBADMSG; 307 308 switch (hctx->ccid3hctx_state) { 309 case TFRC_SSTATE_NO_SENT: 310 sk_reset_timer(sk, &hctx->ccid3hctx_no_feedback_timer, 311 (jiffies + 312 usecs_to_jiffies(TFRC_INITIAL_TIMEOUT))); 313 hctx->ccid3hctx_last_win_count = 0; 314 hctx->ccid3hctx_t_last_win_count = now; 315 316 /* Set t_0 for initial packet */ 317 hctx->ccid3hctx_t_nom = now; 318 319 hctx->ccid3hctx_s = skb->len; 320 321 /* 322 * Use initial RTT sample when available: recommended by erratum 323 * to RFC 4342. This implements the initialisation procedure of 324 * draft rfc3448bis, section 4.2. Remember, X is scaled by 2^6. 325 */ 326 if (dp->dccps_syn_rtt) { 327 ccid3_pr_debug("SYN RTT = %uus\n", dp->dccps_syn_rtt); 328 hctx->ccid3hctx_rtt = dp->dccps_syn_rtt; 329 hctx->ccid3hctx_x = rfc3390_initial_rate(sk); 330 hctx->ccid3hctx_t_ld = now; 331 } else { 332 /* 333 * Sender does not have RTT sample: 334 * - set fallback RTT (RFC 4340, 3.4) since a RTT value 335 * is needed in several parts (e.g. window counter); 336 * - set sending rate X_pps = 1pps as per RFC 3448, 4.2. 337 */ 338 hctx->ccid3hctx_rtt = DCCP_FALLBACK_RTT; 339 hctx->ccid3hctx_x = hctx->ccid3hctx_s; 340 hctx->ccid3hctx_x <<= 6; 341 } 342 ccid3_update_send_interval(hctx); 343 344 ccid3_hc_tx_set_state(sk, TFRC_SSTATE_NO_FBACK); 345 break; 346 case TFRC_SSTATE_NO_FBACK: 347 case TFRC_SSTATE_FBACK: 348 delay = ktime_us_delta(hctx->ccid3hctx_t_nom, now); 349 ccid3_pr_debug("delay=%ld\n", (long)delay); 350 /* 351 * Scheduling of packet transmissions [RFC 3448, 4.6] 352 * 353 * if (t_now > t_nom - delta) 354 * // send the packet now 355 * else 356 * // send the packet in (t_nom - t_now) milliseconds. 357 */ 358 if (delay - (s64)hctx->ccid3hctx_delta >= 1000) 359 return (u32)delay / 1000L; 360 361 ccid3_hc_tx_update_win_count(hctx, now); 362 break; 363 case TFRC_SSTATE_TERM: 364 DCCP_BUG("%s(%p) - Illegal state TERM", dccp_role(sk), sk); 365 return -EINVAL; 366 } 367 368 /* prepare to send now (add options etc.) */ 369 dp->dccps_hc_tx_insert_options = 1; 370 DCCP_SKB_CB(skb)->dccpd_ccval = hctx->ccid3hctx_last_win_count; 371 372 /* set the nominal send time for the next following packet */ 373 hctx->ccid3hctx_t_nom = ktime_add_us(hctx->ccid3hctx_t_nom, 374 hctx->ccid3hctx_t_ipi); 375 return 0; 376 } 377 378 static void ccid3_hc_tx_packet_sent(struct sock *sk, int more, 379 unsigned int len) 380 { 381 struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk); 382 383 ccid3_hc_tx_update_s(hctx, len); 384 385 if (tfrc_tx_hist_add(&hctx->ccid3hctx_hist, dccp_sk(sk)->dccps_gss)) 386 DCCP_CRIT("packet history - out of memory!"); 387 } 388 389 static void ccid3_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb) 390 { 391 struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk); 392 struct ccid3_options_received *opt_recv; 393 ktime_t now; 394 unsigned long t_nfb; 395 u32 pinv, r_sample; 396 397 /* we are only interested in ACKs */ 398 if (!(DCCP_SKB_CB(skb)->dccpd_type == DCCP_PKT_ACK || 399 DCCP_SKB_CB(skb)->dccpd_type == DCCP_PKT_DATAACK)) 400 return; 401 /* ... and only in the established state */ 402 if (hctx->ccid3hctx_state != TFRC_SSTATE_FBACK && 403 hctx->ccid3hctx_state != TFRC_SSTATE_NO_FBACK) 404 return; 405 406 opt_recv = &hctx->ccid3hctx_options_received; 407 now = ktime_get_real(); 408 409 /* Estimate RTT from history if ACK number is valid */ 410 r_sample = tfrc_tx_hist_rtt(hctx->ccid3hctx_hist, 411 DCCP_SKB_CB(skb)->dccpd_ack_seq, now); 412 if (r_sample == 0) { 413 DCCP_WARN("%s(%p): %s with bogus ACK-%llu\n", dccp_role(sk), sk, 414 dccp_packet_name(DCCP_SKB_CB(skb)->dccpd_type), 415 (unsigned long long)DCCP_SKB_CB(skb)->dccpd_ack_seq); 416 return; 417 } 418 419 /* Update receive rate in units of 64 * bytes/second */ 420 hctx->ccid3hctx_x_recv = opt_recv->ccid3or_receive_rate; 421 hctx->ccid3hctx_x_recv <<= 6; 422 423 /* Update loss event rate (which is scaled by 1e6) */ 424 pinv = opt_recv->ccid3or_loss_event_rate; 425 if (pinv == ~0U || pinv == 0) /* see RFC 4342, 8.5 */ 426 hctx->ccid3hctx_p = 0; 427 else /* can not exceed 100% */ 428 hctx->ccid3hctx_p = scaled_div(1, pinv); 429 /* 430 * Validate new RTT sample and update moving average 431 */ 432 r_sample = dccp_sample_rtt(sk, r_sample); 433 hctx->ccid3hctx_rtt = tfrc_ewma(hctx->ccid3hctx_rtt, r_sample, 9); 434 /* 435 * Update allowed sending rate X as per draft rfc3448bis-00, 4.2/3 436 */ 437 if (hctx->ccid3hctx_state == TFRC_SSTATE_NO_FBACK) { 438 ccid3_hc_tx_set_state(sk, TFRC_SSTATE_FBACK); 439 440 if (hctx->ccid3hctx_t_rto == 0) { 441 /* 442 * Initial feedback packet: Larger Initial Windows (4.2) 443 */ 444 hctx->ccid3hctx_x = rfc3390_initial_rate(sk); 445 hctx->ccid3hctx_t_ld = now; 446 447 ccid3_update_send_interval(hctx); 448 449 goto done_computing_x; 450 } else if (hctx->ccid3hctx_p == 0) { 451 /* 452 * First feedback after nofeedback timer expiry (4.3) 453 */ 454 goto done_computing_x; 455 } 456 } 457 458 /* Update sending rate (step 4 of [RFC 3448, 4.3]) */ 459 if (hctx->ccid3hctx_p > 0) 460 hctx->ccid3hctx_x_calc = 461 tfrc_calc_x(hctx->ccid3hctx_s, 462 hctx->ccid3hctx_rtt, 463 hctx->ccid3hctx_p); 464 ccid3_hc_tx_update_x(sk, &now); 465 466 done_computing_x: 467 ccid3_pr_debug("%s(%p), RTT=%uus (sample=%uus), s=%u, " 468 "p=%u, X_calc=%u, X_recv=%u, X=%u\n", 469 dccp_role(sk), 470 sk, hctx->ccid3hctx_rtt, r_sample, 471 hctx->ccid3hctx_s, hctx->ccid3hctx_p, 472 hctx->ccid3hctx_x_calc, 473 (unsigned)(hctx->ccid3hctx_x_recv >> 6), 474 (unsigned)(hctx->ccid3hctx_x >> 6)); 475 476 /* unschedule no feedback timer */ 477 sk_stop_timer(sk, &hctx->ccid3hctx_no_feedback_timer); 478 479 /* 480 * As we have calculated new ipi, delta, t_nom it is possible 481 * that we now can send a packet, so wake up dccp_wait_for_ccid 482 */ 483 sk->sk_write_space(sk); 484 485 /* 486 * Update timeout interval for the nofeedback timer. 487 * We use a configuration option to increase the lower bound. 488 * This can help avoid triggering the nofeedback timer too 489 * often ('spinning') on LANs with small RTTs. 490 */ 491 hctx->ccid3hctx_t_rto = max_t(u32, 4 * hctx->ccid3hctx_rtt, 492 (CONFIG_IP_DCCP_CCID3_RTO * 493 (USEC_PER_SEC / 1000))); 494 /* 495 * Schedule no feedback timer to expire in 496 * max(t_RTO, 2 * s/X) = max(t_RTO, 2 * t_ipi) 497 */ 498 t_nfb = max(hctx->ccid3hctx_t_rto, 2 * hctx->ccid3hctx_t_ipi); 499 500 ccid3_pr_debug("%s(%p), Scheduled no feedback timer to " 501 "expire in %lu jiffies (%luus)\n", 502 dccp_role(sk), 503 sk, usecs_to_jiffies(t_nfb), t_nfb); 504 505 sk_reset_timer(sk, &hctx->ccid3hctx_no_feedback_timer, 506 jiffies + usecs_to_jiffies(t_nfb)); 507 } 508 509 static int ccid3_hc_tx_parse_options(struct sock *sk, unsigned char option, 510 unsigned char len, u16 idx, 511 unsigned char *value) 512 { 513 int rc = 0; 514 const struct dccp_sock *dp = dccp_sk(sk); 515 struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk); 516 struct ccid3_options_received *opt_recv; 517 __be32 opt_val; 518 519 opt_recv = &hctx->ccid3hctx_options_received; 520 521 if (opt_recv->ccid3or_seqno != dp->dccps_gsr) { 522 opt_recv->ccid3or_seqno = dp->dccps_gsr; 523 opt_recv->ccid3or_loss_event_rate = ~0; 524 opt_recv->ccid3or_loss_intervals_idx = 0; 525 opt_recv->ccid3or_loss_intervals_len = 0; 526 opt_recv->ccid3or_receive_rate = 0; 527 } 528 529 switch (option) { 530 case TFRC_OPT_LOSS_EVENT_RATE: 531 if (unlikely(len != 4)) { 532 DCCP_WARN("%s(%p), invalid len %d " 533 "for TFRC_OPT_LOSS_EVENT_RATE\n", 534 dccp_role(sk), sk, len); 535 rc = -EINVAL; 536 } else { 537 opt_val = get_unaligned((__be32 *)value); 538 opt_recv->ccid3or_loss_event_rate = ntohl(opt_val); 539 ccid3_pr_debug("%s(%p), LOSS_EVENT_RATE=%u\n", 540 dccp_role(sk), sk, 541 opt_recv->ccid3or_loss_event_rate); 542 } 543 break; 544 case TFRC_OPT_LOSS_INTERVALS: 545 opt_recv->ccid3or_loss_intervals_idx = idx; 546 opt_recv->ccid3or_loss_intervals_len = len; 547 ccid3_pr_debug("%s(%p), LOSS_INTERVALS=(%u, %u)\n", 548 dccp_role(sk), sk, 549 opt_recv->ccid3or_loss_intervals_idx, 550 opt_recv->ccid3or_loss_intervals_len); 551 break; 552 case TFRC_OPT_RECEIVE_RATE: 553 if (unlikely(len != 4)) { 554 DCCP_WARN("%s(%p), invalid len %d " 555 "for TFRC_OPT_RECEIVE_RATE\n", 556 dccp_role(sk), sk, len); 557 rc = -EINVAL; 558 } else { 559 opt_val = get_unaligned((__be32 *)value); 560 opt_recv->ccid3or_receive_rate = ntohl(opt_val); 561 ccid3_pr_debug("%s(%p), RECEIVE_RATE=%u\n", 562 dccp_role(sk), sk, 563 opt_recv->ccid3or_receive_rate); 564 } 565 break; 566 } 567 568 return rc; 569 } 570 571 static int ccid3_hc_tx_init(struct ccid *ccid, struct sock *sk) 572 { 573 struct ccid3_hc_tx_sock *hctx = ccid_priv(ccid); 574 575 hctx->ccid3hctx_state = TFRC_SSTATE_NO_SENT; 576 hctx->ccid3hctx_hist = NULL; 577 setup_timer(&hctx->ccid3hctx_no_feedback_timer, 578 ccid3_hc_tx_no_feedback_timer, (unsigned long)sk); 579 580 return 0; 581 } 582 583 static void ccid3_hc_tx_exit(struct sock *sk) 584 { 585 struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk); 586 587 ccid3_hc_tx_set_state(sk, TFRC_SSTATE_TERM); 588 sk_stop_timer(sk, &hctx->ccid3hctx_no_feedback_timer); 589 590 tfrc_tx_hist_purge(&hctx->ccid3hctx_hist); 591 } 592 593 static void ccid3_hc_tx_get_info(struct sock *sk, struct tcp_info *info) 594 { 595 struct ccid3_hc_tx_sock *hctx; 596 597 /* Listen socks doesn't have a private CCID block */ 598 if (sk->sk_state == DCCP_LISTEN) 599 return; 600 601 hctx = ccid3_hc_tx_sk(sk); 602 info->tcpi_rto = hctx->ccid3hctx_t_rto; 603 info->tcpi_rtt = hctx->ccid3hctx_rtt; 604 } 605 606 static int ccid3_hc_tx_getsockopt(struct sock *sk, const int optname, int len, 607 u32 __user *optval, int __user *optlen) 608 { 609 const struct ccid3_hc_tx_sock *hctx; 610 const void *val; 611 612 /* Listen socks doesn't have a private CCID block */ 613 if (sk->sk_state == DCCP_LISTEN) 614 return -EINVAL; 615 616 hctx = ccid3_hc_tx_sk(sk); 617 switch (optname) { 618 case DCCP_SOCKOPT_CCID_TX_INFO: 619 if (len < sizeof(hctx->ccid3hctx_tfrc)) 620 return -EINVAL; 621 len = sizeof(hctx->ccid3hctx_tfrc); 622 val = &hctx->ccid3hctx_tfrc; 623 break; 624 default: 625 return -ENOPROTOOPT; 626 } 627 628 if (put_user(len, optlen) || copy_to_user(optval, val, len)) 629 return -EFAULT; 630 631 return 0; 632 } 633 634 /* 635 * Receiver Half-Connection Routines 636 */ 637 638 /* CCID3 feedback types */ 639 enum ccid3_fback_type { 640 CCID3_FBACK_NONE = 0, 641 CCID3_FBACK_INITIAL, 642 CCID3_FBACK_PERIODIC, 643 CCID3_FBACK_PARAM_CHANGE 644 }; 645 646 #ifdef CONFIG_IP_DCCP_CCID3_DEBUG 647 static const char *ccid3_rx_state_name(enum ccid3_hc_rx_states state) 648 { 649 static char *ccid3_rx_state_names[] = { 650 [TFRC_RSTATE_NO_DATA] = "NO_DATA", 651 [TFRC_RSTATE_DATA] = "DATA", 652 [TFRC_RSTATE_TERM] = "TERM", 653 }; 654 655 return ccid3_rx_state_names[state]; 656 } 657 #endif 658 659 static void ccid3_hc_rx_set_state(struct sock *sk, 660 enum ccid3_hc_rx_states state) 661 { 662 struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk); 663 enum ccid3_hc_rx_states oldstate = hcrx->ccid3hcrx_state; 664 665 ccid3_pr_debug("%s(%p) %-8.8s -> %s\n", 666 dccp_role(sk), sk, ccid3_rx_state_name(oldstate), 667 ccid3_rx_state_name(state)); 668 WARN_ON(state == oldstate); 669 hcrx->ccid3hcrx_state = state; 670 } 671 672 static void ccid3_hc_rx_send_feedback(struct sock *sk, 673 const struct sk_buff *skb, 674 enum ccid3_fback_type fbtype) 675 { 676 struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk); 677 struct dccp_sock *dp = dccp_sk(sk); 678 ktime_t now; 679 s64 delta = 0; 680 681 if (unlikely(hcrx->ccid3hcrx_state == TFRC_RSTATE_TERM)) 682 return; 683 684 now = ktime_get_real(); 685 686 switch (fbtype) { 687 case CCID3_FBACK_INITIAL: 688 hcrx->ccid3hcrx_x_recv = 0; 689 hcrx->ccid3hcrx_pinv = ~0U; /* see RFC 4342, 8.5 */ 690 break; 691 case CCID3_FBACK_PARAM_CHANGE: 692 /* 693 * When parameters change (new loss or p > p_prev), we do not 694 * have a reliable estimate for R_m of [RFC 3448, 6.2] and so 695 * need to reuse the previous value of X_recv. However, when 696 * X_recv was 0 (due to early loss), this would kill X down to 697 * s/t_mbi (i.e. one packet in 64 seconds). 698 * To avoid such drastic reduction, we approximate X_recv as 699 * the number of bytes since last feedback. 700 * This is a safe fallback, since X is bounded above by X_calc. 701 */ 702 if (hcrx->ccid3hcrx_x_recv > 0) 703 break; 704 /* fall through */ 705 case CCID3_FBACK_PERIODIC: 706 delta = ktime_us_delta(now, hcrx->ccid3hcrx_tstamp_last_feedback); 707 if (delta <= 0) 708 DCCP_BUG("delta (%ld) <= 0", (long)delta); 709 else 710 hcrx->ccid3hcrx_x_recv = 711 scaled_div32(hcrx->ccid3hcrx_bytes_recv, delta); 712 break; 713 default: 714 return; 715 } 716 717 ccid3_pr_debug("Interval %ldusec, X_recv=%u, 1/p=%u\n", (long)delta, 718 hcrx->ccid3hcrx_x_recv, hcrx->ccid3hcrx_pinv); 719 720 hcrx->ccid3hcrx_tstamp_last_feedback = now; 721 hcrx->ccid3hcrx_last_counter = dccp_hdr(skb)->dccph_ccval; 722 hcrx->ccid3hcrx_bytes_recv = 0; 723 724 dp->dccps_hc_rx_insert_options = 1; 725 dccp_send_ack(sk); 726 } 727 728 static int ccid3_hc_rx_insert_options(struct sock *sk, struct sk_buff *skb) 729 { 730 const struct ccid3_hc_rx_sock *hcrx; 731 __be32 x_recv, pinv; 732 733 if (!(sk->sk_state == DCCP_OPEN || sk->sk_state == DCCP_PARTOPEN)) 734 return 0; 735 736 hcrx = ccid3_hc_rx_sk(sk); 737 738 if (dccp_packet_without_ack(skb)) 739 return 0; 740 741 x_recv = htonl(hcrx->ccid3hcrx_x_recv); 742 pinv = htonl(hcrx->ccid3hcrx_pinv); 743 744 if (dccp_insert_option(sk, skb, TFRC_OPT_LOSS_EVENT_RATE, 745 &pinv, sizeof(pinv)) || 746 dccp_insert_option(sk, skb, TFRC_OPT_RECEIVE_RATE, 747 &x_recv, sizeof(x_recv))) 748 return -1; 749 750 return 0; 751 } 752 753 /** ccid3_first_li - Implements [RFC 3448, 6.3.1] 754 * 755 * Determine the length of the first loss interval via inverse lookup. 756 * Assume that X_recv can be computed by the throughput equation 757 * s 758 * X_recv = -------- 759 * R * fval 760 * Find some p such that f(p) = fval; return 1/p (scaled). 761 */ 762 static u32 ccid3_first_li(struct sock *sk) 763 { 764 struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk); 765 u32 x_recv, p, delta; 766 u64 fval; 767 768 if (hcrx->ccid3hcrx_rtt == 0) { 769 DCCP_WARN("No RTT estimate available, using fallback RTT\n"); 770 hcrx->ccid3hcrx_rtt = DCCP_FALLBACK_RTT; 771 } 772 773 delta = ktime_to_us(net_timedelta(hcrx->ccid3hcrx_tstamp_last_feedback)); 774 x_recv = scaled_div32(hcrx->ccid3hcrx_bytes_recv, delta); 775 if (x_recv == 0) { /* would also trigger divide-by-zero */ 776 DCCP_WARN("X_recv==0\n"); 777 if ((x_recv = hcrx->ccid3hcrx_x_recv) == 0) { 778 DCCP_BUG("stored value of X_recv is zero"); 779 return ~0U; 780 } 781 } 782 783 fval = scaled_div(hcrx->ccid3hcrx_s, hcrx->ccid3hcrx_rtt); 784 fval = scaled_div32(fval, x_recv); 785 p = tfrc_calc_x_reverse_lookup(fval); 786 787 ccid3_pr_debug("%s(%p), receive rate=%u bytes/s, implied " 788 "loss rate=%u\n", dccp_role(sk), sk, x_recv, p); 789 790 return p == 0 ? ~0U : scaled_div(1, p); 791 } 792 793 static void ccid3_hc_rx_packet_recv(struct sock *sk, struct sk_buff *skb) 794 { 795 struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk); 796 enum ccid3_fback_type do_feedback = CCID3_FBACK_NONE; 797 const u64 ndp = dccp_sk(sk)->dccps_options_received.dccpor_ndp; 798 const bool is_data_packet = dccp_data_packet(skb); 799 800 if (unlikely(hcrx->ccid3hcrx_state == TFRC_RSTATE_NO_DATA)) { 801 if (is_data_packet) { 802 const u32 payload = skb->len - dccp_hdr(skb)->dccph_doff * 4; 803 do_feedback = CCID3_FBACK_INITIAL; 804 ccid3_hc_rx_set_state(sk, TFRC_RSTATE_DATA); 805 hcrx->ccid3hcrx_s = payload; 806 /* 807 * Not necessary to update ccid3hcrx_bytes_recv here, 808 * since X_recv = 0 for the first feedback packet (cf. 809 * RFC 3448, 6.3) -- gerrit 810 */ 811 } 812 goto update_records; 813 } 814 815 if (tfrc_rx_hist_duplicate(&hcrx->ccid3hcrx_hist, skb)) 816 return; /* done receiving */ 817 818 if (is_data_packet) { 819 const u32 payload = skb->len - dccp_hdr(skb)->dccph_doff * 4; 820 /* 821 * Update moving-average of s and the sum of received payload bytes 822 */ 823 hcrx->ccid3hcrx_s = tfrc_ewma(hcrx->ccid3hcrx_s, payload, 9); 824 hcrx->ccid3hcrx_bytes_recv += payload; 825 } 826 827 /* 828 * Perform loss detection and handle pending losses 829 */ 830 if (tfrc_rx_handle_loss(&hcrx->ccid3hcrx_hist, &hcrx->ccid3hcrx_li_hist, 831 skb, ndp, ccid3_first_li, sk)) { 832 do_feedback = CCID3_FBACK_PARAM_CHANGE; 833 goto done_receiving; 834 } 835 836 if (tfrc_rx_hist_loss_pending(&hcrx->ccid3hcrx_hist)) 837 return; /* done receiving */ 838 839 /* 840 * Handle data packets: RTT sampling and monitoring p 841 */ 842 if (unlikely(!is_data_packet)) 843 goto update_records; 844 845 if (!tfrc_lh_is_initialised(&hcrx->ccid3hcrx_li_hist)) { 846 const u32 sample = tfrc_rx_hist_sample_rtt(&hcrx->ccid3hcrx_hist, skb); 847 /* 848 * Empty loss history: no loss so far, hence p stays 0. 849 * Sample RTT values, since an RTT estimate is required for the 850 * computation of p when the first loss occurs; RFC 3448, 6.3.1. 851 */ 852 if (sample != 0) 853 hcrx->ccid3hcrx_rtt = tfrc_ewma(hcrx->ccid3hcrx_rtt, sample, 9); 854 855 } else if (tfrc_lh_update_i_mean(&hcrx->ccid3hcrx_li_hist, skb)) { 856 /* 857 * Step (3) of [RFC 3448, 6.1]: Recompute I_mean and, if I_mean 858 * has decreased (resp. p has increased), send feedback now. 859 */ 860 do_feedback = CCID3_FBACK_PARAM_CHANGE; 861 } 862 863 /* 864 * Check if the periodic once-per-RTT feedback is due; RFC 4342, 10.3 865 */ 866 if (SUB16(dccp_hdr(skb)->dccph_ccval, hcrx->ccid3hcrx_last_counter) > 3) 867 do_feedback = CCID3_FBACK_PERIODIC; 868 869 update_records: 870 tfrc_rx_hist_add_packet(&hcrx->ccid3hcrx_hist, skb, ndp); 871 872 done_receiving: 873 if (do_feedback) 874 ccid3_hc_rx_send_feedback(sk, skb, do_feedback); 875 } 876 877 static int ccid3_hc_rx_init(struct ccid *ccid, struct sock *sk) 878 { 879 struct ccid3_hc_rx_sock *hcrx = ccid_priv(ccid); 880 881 hcrx->ccid3hcrx_state = TFRC_RSTATE_NO_DATA; 882 tfrc_lh_init(&hcrx->ccid3hcrx_li_hist); 883 return tfrc_rx_hist_alloc(&hcrx->ccid3hcrx_hist); 884 } 885 886 static void ccid3_hc_rx_exit(struct sock *sk) 887 { 888 struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk); 889 890 ccid3_hc_rx_set_state(sk, TFRC_RSTATE_TERM); 891 892 tfrc_rx_hist_purge(&hcrx->ccid3hcrx_hist); 893 tfrc_lh_cleanup(&hcrx->ccid3hcrx_li_hist); 894 } 895 896 static void ccid3_hc_rx_get_info(struct sock *sk, struct tcp_info *info) 897 { 898 const struct ccid3_hc_rx_sock *hcrx; 899 900 /* Listen socks doesn't have a private CCID block */ 901 if (sk->sk_state == DCCP_LISTEN) 902 return; 903 904 hcrx = ccid3_hc_rx_sk(sk); 905 info->tcpi_ca_state = hcrx->ccid3hcrx_state; 906 info->tcpi_options |= TCPI_OPT_TIMESTAMPS; 907 info->tcpi_rcv_rtt = hcrx->ccid3hcrx_rtt; 908 } 909 910 static int ccid3_hc_rx_getsockopt(struct sock *sk, const int optname, int len, 911 u32 __user *optval, int __user *optlen) 912 { 913 const struct ccid3_hc_rx_sock *hcrx; 914 struct tfrc_rx_info rx_info; 915 const void *val; 916 917 /* Listen socks doesn't have a private CCID block */ 918 if (sk->sk_state == DCCP_LISTEN) 919 return -EINVAL; 920 921 hcrx = ccid3_hc_rx_sk(sk); 922 switch (optname) { 923 case DCCP_SOCKOPT_CCID_RX_INFO: 924 if (len < sizeof(rx_info)) 925 return -EINVAL; 926 rx_info.tfrcrx_x_recv = hcrx->ccid3hcrx_x_recv; 927 rx_info.tfrcrx_rtt = hcrx->ccid3hcrx_rtt; 928 rx_info.tfrcrx_p = hcrx->ccid3hcrx_pinv == 0 ? ~0U : 929 scaled_div(1, hcrx->ccid3hcrx_pinv); 930 len = sizeof(rx_info); 931 val = &rx_info; 932 break; 933 default: 934 return -ENOPROTOOPT; 935 } 936 937 if (put_user(len, optlen) || copy_to_user(optval, val, len)) 938 return -EFAULT; 939 940 return 0; 941 } 942 943 struct ccid_operations ccid3_ops = { 944 .ccid_id = DCCPC_CCID3, 945 .ccid_name = "TCP-Friendly Rate Control", 946 .ccid_hc_tx_obj_size = sizeof(struct ccid3_hc_tx_sock), 947 .ccid_hc_tx_init = ccid3_hc_tx_init, 948 .ccid_hc_tx_exit = ccid3_hc_tx_exit, 949 .ccid_hc_tx_send_packet = ccid3_hc_tx_send_packet, 950 .ccid_hc_tx_packet_sent = ccid3_hc_tx_packet_sent, 951 .ccid_hc_tx_packet_recv = ccid3_hc_tx_packet_recv, 952 .ccid_hc_tx_parse_options = ccid3_hc_tx_parse_options, 953 .ccid_hc_rx_obj_size = sizeof(struct ccid3_hc_rx_sock), 954 .ccid_hc_rx_init = ccid3_hc_rx_init, 955 .ccid_hc_rx_exit = ccid3_hc_rx_exit, 956 .ccid_hc_rx_insert_options = ccid3_hc_rx_insert_options, 957 .ccid_hc_rx_packet_recv = ccid3_hc_rx_packet_recv, 958 .ccid_hc_rx_get_info = ccid3_hc_rx_get_info, 959 .ccid_hc_tx_get_info = ccid3_hc_tx_get_info, 960 .ccid_hc_rx_getsockopt = ccid3_hc_rx_getsockopt, 961 .ccid_hc_tx_getsockopt = ccid3_hc_tx_getsockopt, 962 }; 963 964 #ifdef CONFIG_IP_DCCP_CCID3_DEBUG 965 module_param(ccid3_debug, bool, 0644); 966 MODULE_PARM_DESC(ccid3_debug, "Enable CCID-3 debug messages"); 967 #endif 968