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 = min_t(__u32, 4 * hctx->ccid3hctx_s, 92 max_t(__u32, 2 * hctx->ccid3hctx_s, 4380)); 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 = 163 max(min(2 * hctx->ccid3hctx_x, min_rate), 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 * The algorithm is not applicable if RTT < 4 microseconds. 197 */ 198 static inline void ccid3_hc_tx_update_win_count(struct ccid3_hc_tx_sock *hctx, 199 ktime_t now) 200 { 201 u32 quarter_rtts; 202 203 if (unlikely(hctx->ccid3hctx_rtt < 4)) /* avoid divide-by-zero */ 204 return; 205 206 quarter_rtts = ktime_us_delta(now, hctx->ccid3hctx_t_last_win_count); 207 quarter_rtts /= hctx->ccid3hctx_rtt / 4; 208 209 if (quarter_rtts > 0) { 210 hctx->ccid3hctx_t_last_win_count = now; 211 hctx->ccid3hctx_last_win_count += min_t(u32, quarter_rtts, 5); 212 hctx->ccid3hctx_last_win_count &= 0xF; /* mod 16 */ 213 } 214 } 215 216 static void ccid3_hc_tx_no_feedback_timer(unsigned long data) 217 { 218 struct sock *sk = (struct sock *)data; 219 struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk); 220 unsigned long t_nfb = USEC_PER_SEC / 5; 221 222 bh_lock_sock(sk); 223 if (sock_owned_by_user(sk)) { 224 /* Try again later. */ 225 /* XXX: set some sensible MIB */ 226 goto restart_timer; 227 } 228 229 ccid3_pr_debug("%s(%p, state=%s) - entry \n", dccp_role(sk), sk, 230 ccid3_tx_state_name(hctx->ccid3hctx_state)); 231 232 if (hctx->ccid3hctx_state == TFRC_SSTATE_FBACK) 233 ccid3_hc_tx_set_state(sk, TFRC_SSTATE_NO_FBACK); 234 else if (hctx->ccid3hctx_state != TFRC_SSTATE_NO_FBACK) 235 goto out; 236 237 /* 238 * Determine new allowed sending rate X as per draft rfc3448bis-00, 4.4 239 */ 240 if (hctx->ccid3hctx_t_rto == 0 || /* no feedback received yet */ 241 hctx->ccid3hctx_p == 0) { 242 243 /* halve send rate directly */ 244 hctx->ccid3hctx_x = max(hctx->ccid3hctx_x / 2, 245 (((__u64)hctx->ccid3hctx_s) << 6) / 246 TFRC_T_MBI); 247 ccid3_update_send_interval(hctx); 248 } else { 249 /* 250 * Modify the cached value of X_recv 251 * 252 * If (X_calc > 2 * X_recv) 253 * X_recv = max(X_recv / 2, s / (2 * t_mbi)); 254 * Else 255 * X_recv = X_calc / 4; 256 * 257 * Note that X_recv is scaled by 2^6 while X_calc is not 258 */ 259 BUG_ON(hctx->ccid3hctx_p && !hctx->ccid3hctx_x_calc); 260 261 if (hctx->ccid3hctx_x_calc > (hctx->ccid3hctx_x_recv >> 5)) 262 hctx->ccid3hctx_x_recv = 263 max(hctx->ccid3hctx_x_recv / 2, 264 (((__u64)hctx->ccid3hctx_s) << 6) / 265 (2 * TFRC_T_MBI)); 266 else { 267 hctx->ccid3hctx_x_recv = hctx->ccid3hctx_x_calc; 268 hctx->ccid3hctx_x_recv <<= 4; 269 } 270 ccid3_hc_tx_update_x(sk, NULL); 271 } 272 ccid3_pr_debug("Reduced X to %llu/64 bytes/sec\n", 273 (unsigned long long)hctx->ccid3hctx_x); 274 275 /* 276 * Set new timeout for the nofeedback timer. 277 * See comments in packet_recv() regarding the value of t_RTO. 278 */ 279 if (unlikely(hctx->ccid3hctx_t_rto == 0)) /* no feedback yet */ 280 t_nfb = TFRC_INITIAL_TIMEOUT; 281 else 282 t_nfb = max(hctx->ccid3hctx_t_rto, 2 * hctx->ccid3hctx_t_ipi); 283 284 restart_timer: 285 sk_reset_timer(sk, &hctx->ccid3hctx_no_feedback_timer, 286 jiffies + usecs_to_jiffies(t_nfb)); 287 out: 288 bh_unlock_sock(sk); 289 sock_put(sk); 290 } 291 292 /* 293 * returns 294 * > 0: delay (in msecs) that should pass before actually sending 295 * = 0: can send immediately 296 * < 0: error condition; do not send packet 297 */ 298 static int ccid3_hc_tx_send_packet(struct sock *sk, struct sk_buff *skb) 299 { 300 struct dccp_sock *dp = dccp_sk(sk); 301 struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk); 302 ktime_t now = ktime_get_real(); 303 s64 delay; 304 305 /* 306 * This function is called only for Data and DataAck packets. Sending 307 * zero-sized Data(Ack)s is theoretically possible, but for congestion 308 * control this case is pathological - ignore it. 309 */ 310 if (unlikely(skb->len == 0)) 311 return -EBADMSG; 312 313 switch (hctx->ccid3hctx_state) { 314 case TFRC_SSTATE_NO_SENT: 315 sk_reset_timer(sk, &hctx->ccid3hctx_no_feedback_timer, 316 (jiffies + 317 usecs_to_jiffies(TFRC_INITIAL_TIMEOUT))); 318 hctx->ccid3hctx_last_win_count = 0; 319 hctx->ccid3hctx_t_last_win_count = now; 320 321 /* Set t_0 for initial packet */ 322 hctx->ccid3hctx_t_nom = now; 323 324 hctx->ccid3hctx_s = skb->len; 325 326 /* 327 * Use initial RTT sample when available: recommended by erratum 328 * to RFC 4342. This implements the initialisation procedure of 329 * draft rfc3448bis, section 4.2. Remember, X is scaled by 2^6. 330 */ 331 if (dp->dccps_syn_rtt) { 332 ccid3_pr_debug("SYN RTT = %uus\n", dp->dccps_syn_rtt); 333 hctx->ccid3hctx_rtt = dp->dccps_syn_rtt; 334 hctx->ccid3hctx_x = rfc3390_initial_rate(sk); 335 hctx->ccid3hctx_t_ld = now; 336 } else { 337 /* Sender does not have RTT sample: X_pps = 1 pkt/sec */ 338 hctx->ccid3hctx_x = hctx->ccid3hctx_s; 339 hctx->ccid3hctx_x <<= 6; 340 } 341 ccid3_update_send_interval(hctx); 342 343 ccid3_hc_tx_set_state(sk, TFRC_SSTATE_NO_FBACK); 344 break; 345 case TFRC_SSTATE_NO_FBACK: 346 case TFRC_SSTATE_FBACK: 347 delay = ktime_us_delta(hctx->ccid3hctx_t_nom, now); 348 ccid3_pr_debug("delay=%ld\n", (long)delay); 349 /* 350 * Scheduling of packet transmissions [RFC 3448, 4.6] 351 * 352 * if (t_now > t_nom - delta) 353 * // send the packet now 354 * else 355 * // send the packet in (t_nom - t_now) milliseconds. 356 */ 357 if (delay - (s64)hctx->ccid3hctx_delta >= 1000) 358 return (u32)delay / 1000L; 359 360 ccid3_hc_tx_update_win_count(hctx, now); 361 break; 362 case TFRC_SSTATE_TERM: 363 DCCP_BUG("%s(%p) - Illegal state TERM", dccp_role(sk), sk); 364 return -EINVAL; 365 } 366 367 /* prepare to send now (add options etc.) */ 368 dp->dccps_hc_tx_insert_options = 1; 369 DCCP_SKB_CB(skb)->dccpd_ccval = hctx->ccid3hctx_last_win_count; 370 371 /* set the nominal send time for the next following packet */ 372 hctx->ccid3hctx_t_nom = ktime_add_us(hctx->ccid3hctx_t_nom, 373 hctx->ccid3hctx_t_ipi); 374 return 0; 375 } 376 377 static void ccid3_hc_tx_packet_sent(struct sock *sk, int more, 378 unsigned int len) 379 { 380 struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk); 381 382 ccid3_hc_tx_update_s(hctx, len); 383 384 if (tfrc_tx_hist_add(&hctx->ccid3hctx_hist, dccp_sk(sk)->dccps_gss)) 385 DCCP_CRIT("packet history - out of memory!"); 386 } 387 388 static void ccid3_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb) 389 { 390 struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk); 391 struct ccid3_options_received *opt_recv; 392 ktime_t now; 393 unsigned long t_nfb; 394 u32 pinv, r_sample; 395 396 /* we are only interested in ACKs */ 397 if (!(DCCP_SKB_CB(skb)->dccpd_type == DCCP_PKT_ACK || 398 DCCP_SKB_CB(skb)->dccpd_type == DCCP_PKT_DATAACK)) 399 return; 400 /* ... and only in the established state */ 401 if (hctx->ccid3hctx_state != TFRC_SSTATE_FBACK && 402 hctx->ccid3hctx_state != TFRC_SSTATE_NO_FBACK) 403 return; 404 405 opt_recv = &hctx->ccid3hctx_options_received; 406 now = ktime_get_real(); 407 408 /* Estimate RTT from history if ACK number is valid */ 409 r_sample = tfrc_tx_hist_rtt(hctx->ccid3hctx_hist, 410 DCCP_SKB_CB(skb)->dccpd_ack_seq, now); 411 if (r_sample == 0) { 412 DCCP_WARN("%s(%p): %s with bogus ACK-%llu\n", dccp_role(sk), sk, 413 dccp_packet_name(DCCP_SKB_CB(skb)->dccpd_type), 414 (unsigned long long)DCCP_SKB_CB(skb)->dccpd_ack_seq); 415 return; 416 } 417 418 /* Update receive rate in units of 64 * bytes/second */ 419 hctx->ccid3hctx_x_recv = opt_recv->ccid3or_receive_rate; 420 hctx->ccid3hctx_x_recv <<= 6; 421 422 /* Update loss event rate (which is scaled by 1e6) */ 423 pinv = opt_recv->ccid3or_loss_event_rate; 424 if (pinv == ~0U || pinv == 0) /* see RFC 4342, 8.5 */ 425 hctx->ccid3hctx_p = 0; 426 else /* can not exceed 100% */ 427 hctx->ccid3hctx_p = scaled_div(1, pinv); 428 /* 429 * Validate new RTT sample and update moving average 430 */ 431 r_sample = dccp_sample_rtt(sk, r_sample); 432 hctx->ccid3hctx_rtt = tfrc_ewma(hctx->ccid3hctx_rtt, r_sample, 9); 433 /* 434 * Update allowed sending rate X as per draft rfc3448bis-00, 4.2/3 435 */ 436 if (hctx->ccid3hctx_state == TFRC_SSTATE_NO_FBACK) { 437 ccid3_hc_tx_set_state(sk, TFRC_SSTATE_FBACK); 438 439 if (hctx->ccid3hctx_t_rto == 0) { 440 /* 441 * Initial feedback packet: Larger Initial Windows (4.2) 442 */ 443 hctx->ccid3hctx_x = rfc3390_initial_rate(sk); 444 hctx->ccid3hctx_t_ld = now; 445 446 ccid3_update_send_interval(hctx); 447 448 goto done_computing_x; 449 } else if (hctx->ccid3hctx_p == 0) { 450 /* 451 * First feedback after nofeedback timer expiry (4.3) 452 */ 453 goto done_computing_x; 454 } 455 } 456 457 /* Update sending rate (step 4 of [RFC 3448, 4.3]) */ 458 if (hctx->ccid3hctx_p > 0) 459 hctx->ccid3hctx_x_calc = 460 tfrc_calc_x(hctx->ccid3hctx_s, 461 hctx->ccid3hctx_rtt, 462 hctx->ccid3hctx_p); 463 ccid3_hc_tx_update_x(sk, &now); 464 465 done_computing_x: 466 ccid3_pr_debug("%s(%p), RTT=%uus (sample=%uus), s=%u, " 467 "p=%u, X_calc=%u, X_recv=%u, X=%u\n", 468 dccp_role(sk), 469 sk, hctx->ccid3hctx_rtt, r_sample, 470 hctx->ccid3hctx_s, hctx->ccid3hctx_p, 471 hctx->ccid3hctx_x_calc, 472 (unsigned)(hctx->ccid3hctx_x_recv >> 6), 473 (unsigned)(hctx->ccid3hctx_x >> 6)); 474 475 /* unschedule no feedback timer */ 476 sk_stop_timer(sk, &hctx->ccid3hctx_no_feedback_timer); 477 478 /* 479 * As we have calculated new ipi, delta, t_nom it is possible 480 * that we now can send a packet, so wake up dccp_wait_for_ccid 481 */ 482 sk->sk_write_space(sk); 483 484 /* 485 * Update timeout interval for the nofeedback timer. 486 * We use a configuration option to increase the lower bound. 487 * This can help avoid triggering the nofeedback timer too 488 * often ('spinning') on LANs with small RTTs. 489 */ 490 hctx->ccid3hctx_t_rto = max_t(u32, 4 * hctx->ccid3hctx_rtt, 491 (CONFIG_IP_DCCP_CCID3_RTO * 492 (USEC_PER_SEC / 1000))); 493 /* 494 * Schedule no feedback timer to expire in 495 * max(t_RTO, 2 * s/X) = max(t_RTO, 2 * t_ipi) 496 */ 497 t_nfb = max(hctx->ccid3hctx_t_rto, 2 * hctx->ccid3hctx_t_ipi); 498 499 ccid3_pr_debug("%s(%p), Scheduled no feedback timer to " 500 "expire in %lu jiffies (%luus)\n", 501 dccp_role(sk), 502 sk, usecs_to_jiffies(t_nfb), t_nfb); 503 504 sk_reset_timer(sk, &hctx->ccid3hctx_no_feedback_timer, 505 jiffies + usecs_to_jiffies(t_nfb)); 506 } 507 508 static int ccid3_hc_tx_parse_options(struct sock *sk, unsigned char option, 509 unsigned char len, u16 idx, 510 unsigned char *value) 511 { 512 int rc = 0; 513 const struct dccp_sock *dp = dccp_sk(sk); 514 struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk); 515 struct ccid3_options_received *opt_recv; 516 __be32 opt_val; 517 518 opt_recv = &hctx->ccid3hctx_options_received; 519 520 if (opt_recv->ccid3or_seqno != dp->dccps_gsr) { 521 opt_recv->ccid3or_seqno = dp->dccps_gsr; 522 opt_recv->ccid3or_loss_event_rate = ~0; 523 opt_recv->ccid3or_loss_intervals_idx = 0; 524 opt_recv->ccid3or_loss_intervals_len = 0; 525 opt_recv->ccid3or_receive_rate = 0; 526 } 527 528 switch (option) { 529 case TFRC_OPT_LOSS_EVENT_RATE: 530 if (unlikely(len != 4)) { 531 DCCP_WARN("%s(%p), invalid len %d " 532 "for TFRC_OPT_LOSS_EVENT_RATE\n", 533 dccp_role(sk), sk, len); 534 rc = -EINVAL; 535 } else { 536 opt_val = get_unaligned((__be32 *)value); 537 opt_recv->ccid3or_loss_event_rate = ntohl(opt_val); 538 ccid3_pr_debug("%s(%p), LOSS_EVENT_RATE=%u\n", 539 dccp_role(sk), sk, 540 opt_recv->ccid3or_loss_event_rate); 541 } 542 break; 543 case TFRC_OPT_LOSS_INTERVALS: 544 opt_recv->ccid3or_loss_intervals_idx = idx; 545 opt_recv->ccid3or_loss_intervals_len = len; 546 ccid3_pr_debug("%s(%p), LOSS_INTERVALS=(%u, %u)\n", 547 dccp_role(sk), sk, 548 opt_recv->ccid3or_loss_intervals_idx, 549 opt_recv->ccid3or_loss_intervals_len); 550 break; 551 case TFRC_OPT_RECEIVE_RATE: 552 if (unlikely(len != 4)) { 553 DCCP_WARN("%s(%p), invalid len %d " 554 "for TFRC_OPT_RECEIVE_RATE\n", 555 dccp_role(sk), sk, len); 556 rc = -EINVAL; 557 } else { 558 opt_val = get_unaligned((__be32 *)value); 559 opt_recv->ccid3or_receive_rate = ntohl(opt_val); 560 ccid3_pr_debug("%s(%p), RECEIVE_RATE=%u\n", 561 dccp_role(sk), sk, 562 opt_recv->ccid3or_receive_rate); 563 } 564 break; 565 } 566 567 return rc; 568 } 569 570 static int ccid3_hc_tx_init(struct ccid *ccid, struct sock *sk) 571 { 572 struct ccid3_hc_tx_sock *hctx = ccid_priv(ccid); 573 574 hctx->ccid3hctx_state = TFRC_SSTATE_NO_SENT; 575 hctx->ccid3hctx_hist = NULL; 576 setup_timer(&hctx->ccid3hctx_no_feedback_timer, 577 ccid3_hc_tx_no_feedback_timer, (unsigned long)sk); 578 579 return 0; 580 } 581 582 static void ccid3_hc_tx_exit(struct sock *sk) 583 { 584 struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk); 585 586 ccid3_hc_tx_set_state(sk, TFRC_SSTATE_TERM); 587 sk_stop_timer(sk, &hctx->ccid3hctx_no_feedback_timer); 588 589 tfrc_tx_hist_purge(&hctx->ccid3hctx_hist); 590 } 591 592 static void ccid3_hc_tx_get_info(struct sock *sk, struct tcp_info *info) 593 { 594 struct ccid3_hc_tx_sock *hctx; 595 596 /* Listen socks doesn't have a private CCID block */ 597 if (sk->sk_state == DCCP_LISTEN) 598 return; 599 600 hctx = ccid3_hc_tx_sk(sk); 601 info->tcpi_rto = hctx->ccid3hctx_t_rto; 602 info->tcpi_rtt = hctx->ccid3hctx_rtt; 603 } 604 605 static int ccid3_hc_tx_getsockopt(struct sock *sk, const int optname, int len, 606 u32 __user *optval, int __user *optlen) 607 { 608 const struct ccid3_hc_tx_sock *hctx; 609 const void *val; 610 611 /* Listen socks doesn't have a private CCID block */ 612 if (sk->sk_state == DCCP_LISTEN) 613 return -EINVAL; 614 615 hctx = ccid3_hc_tx_sk(sk); 616 switch (optname) { 617 case DCCP_SOCKOPT_CCID_TX_INFO: 618 if (len < sizeof(hctx->ccid3hctx_tfrc)) 619 return -EINVAL; 620 len = sizeof(hctx->ccid3hctx_tfrc); 621 val = &hctx->ccid3hctx_tfrc; 622 break; 623 default: 624 return -ENOPROTOOPT; 625 } 626 627 if (put_user(len, optlen) || copy_to_user(optval, val, len)) 628 return -EFAULT; 629 630 return 0; 631 } 632 633 /* 634 * Receiver Half-Connection Routines 635 */ 636 637 /* CCID3 feedback types */ 638 enum ccid3_fback_type { 639 CCID3_FBACK_NONE = 0, 640 CCID3_FBACK_INITIAL, 641 CCID3_FBACK_PERIODIC, 642 CCID3_FBACK_PARAM_CHANGE 643 }; 644 645 #ifdef CONFIG_IP_DCCP_CCID3_DEBUG 646 static const char *ccid3_rx_state_name(enum ccid3_hc_rx_states state) 647 { 648 static char *ccid3_rx_state_names[] = { 649 [TFRC_RSTATE_NO_DATA] = "NO_DATA", 650 [TFRC_RSTATE_DATA] = "DATA", 651 [TFRC_RSTATE_TERM] = "TERM", 652 }; 653 654 return ccid3_rx_state_names[state]; 655 } 656 #endif 657 658 static void ccid3_hc_rx_set_state(struct sock *sk, 659 enum ccid3_hc_rx_states state) 660 { 661 struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk); 662 enum ccid3_hc_rx_states oldstate = hcrx->ccid3hcrx_state; 663 664 ccid3_pr_debug("%s(%p) %-8.8s -> %s\n", 665 dccp_role(sk), sk, ccid3_rx_state_name(oldstate), 666 ccid3_rx_state_name(state)); 667 WARN_ON(state == oldstate); 668 hcrx->ccid3hcrx_state = state; 669 } 670 671 static void ccid3_hc_rx_send_feedback(struct sock *sk, 672 const struct sk_buff *skb, 673 enum ccid3_fback_type fbtype) 674 { 675 struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk); 676 struct dccp_sock *dp = dccp_sk(sk); 677 ktime_t now; 678 s64 delta = 0; 679 680 if (unlikely(hcrx->ccid3hcrx_state == TFRC_RSTATE_TERM)) 681 return; 682 683 now = ktime_get_real(); 684 685 switch (fbtype) { 686 case CCID3_FBACK_INITIAL: 687 hcrx->ccid3hcrx_x_recv = 0; 688 hcrx->ccid3hcrx_pinv = ~0U; /* see RFC 4342, 8.5 */ 689 break; 690 case CCID3_FBACK_PARAM_CHANGE: 691 /* 692 * When parameters change (new loss or p > p_prev), we do not 693 * have a reliable estimate for R_m of [RFC 3448, 6.2] and so 694 * need to reuse the previous value of X_recv. However, when 695 * X_recv was 0 (due to early loss), this would kill X down to 696 * s/t_mbi (i.e. one packet in 64 seconds). 697 * To avoid such drastic reduction, we approximate X_recv as 698 * the number of bytes since last feedback. 699 * This is a safe fallback, since X is bounded above by X_calc. 700 */ 701 if (hcrx->ccid3hcrx_x_recv > 0) 702 break; 703 /* fall through */ 704 case CCID3_FBACK_PERIODIC: 705 delta = ktime_us_delta(now, hcrx->ccid3hcrx_tstamp_last_feedback); 706 if (delta <= 0) 707 DCCP_BUG("delta (%ld) <= 0", (long)delta); 708 else 709 hcrx->ccid3hcrx_x_recv = 710 scaled_div32(hcrx->ccid3hcrx_bytes_recv, delta); 711 break; 712 default: 713 return; 714 } 715 716 ccid3_pr_debug("Interval %ldusec, X_recv=%u, 1/p=%u\n", (long)delta, 717 hcrx->ccid3hcrx_x_recv, hcrx->ccid3hcrx_pinv); 718 719 hcrx->ccid3hcrx_tstamp_last_feedback = now; 720 hcrx->ccid3hcrx_last_counter = dccp_hdr(skb)->dccph_ccval; 721 hcrx->ccid3hcrx_bytes_recv = 0; 722 723 dp->dccps_hc_rx_insert_options = 1; 724 dccp_send_ack(sk); 725 } 726 727 static int ccid3_hc_rx_insert_options(struct sock *sk, struct sk_buff *skb) 728 { 729 const struct ccid3_hc_rx_sock *hcrx; 730 __be32 x_recv, pinv; 731 732 if (!(sk->sk_state == DCCP_OPEN || sk->sk_state == DCCP_PARTOPEN)) 733 return 0; 734 735 hcrx = ccid3_hc_rx_sk(sk); 736 737 if (dccp_packet_without_ack(skb)) 738 return 0; 739 740 x_recv = htonl(hcrx->ccid3hcrx_x_recv); 741 pinv = htonl(hcrx->ccid3hcrx_pinv); 742 743 if (dccp_insert_option(sk, skb, TFRC_OPT_LOSS_EVENT_RATE, 744 &pinv, sizeof(pinv)) || 745 dccp_insert_option(sk, skb, TFRC_OPT_RECEIVE_RATE, 746 &x_recv, sizeof(x_recv))) 747 return -1; 748 749 return 0; 750 } 751 752 /** ccid3_first_li - Implements [RFC 3448, 6.3.1] 753 * 754 * Determine the length of the first loss interval via inverse lookup. 755 * Assume that X_recv can be computed by the throughput equation 756 * s 757 * X_recv = -------- 758 * R * fval 759 * Find some p such that f(p) = fval; return 1/p (scaled). 760 */ 761 static u32 ccid3_first_li(struct sock *sk) 762 { 763 struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk); 764 u32 x_recv, p, delta; 765 u64 fval; 766 767 if (hcrx->ccid3hcrx_rtt == 0) { 768 DCCP_WARN("No RTT estimate available, using fallback RTT\n"); 769 hcrx->ccid3hcrx_rtt = DCCP_FALLBACK_RTT; 770 } 771 772 delta = ktime_to_us(net_timedelta(hcrx->ccid3hcrx_tstamp_last_feedback)); 773 x_recv = scaled_div32(hcrx->ccid3hcrx_bytes_recv, delta); 774 if (x_recv == 0) { /* would also trigger divide-by-zero */ 775 DCCP_WARN("X_recv==0\n"); 776 if ((x_recv = hcrx->ccid3hcrx_x_recv) == 0) { 777 DCCP_BUG("stored value of X_recv is zero"); 778 return ~0U; 779 } 780 } 781 782 fval = scaled_div(hcrx->ccid3hcrx_s, hcrx->ccid3hcrx_rtt); 783 fval = scaled_div32(fval, x_recv); 784 p = tfrc_calc_x_reverse_lookup(fval); 785 786 ccid3_pr_debug("%s(%p), receive rate=%u bytes/s, implied " 787 "loss rate=%u\n", dccp_role(sk), sk, x_recv, p); 788 789 return p == 0 ? ~0U : scaled_div(1, p); 790 } 791 792 static void ccid3_hc_rx_packet_recv(struct sock *sk, struct sk_buff *skb) 793 { 794 struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk); 795 enum ccid3_fback_type do_feedback = CCID3_FBACK_NONE; 796 const u32 ndp = dccp_sk(sk)->dccps_options_received.dccpor_ndp; 797 const bool is_data_packet = dccp_data_packet(skb); 798 799 if (unlikely(hcrx->ccid3hcrx_state == TFRC_RSTATE_NO_DATA)) { 800 if (is_data_packet) { 801 const u32 payload = skb->len - dccp_hdr(skb)->dccph_doff * 4; 802 do_feedback = CCID3_FBACK_INITIAL; 803 ccid3_hc_rx_set_state(sk, TFRC_RSTATE_DATA); 804 hcrx->ccid3hcrx_s = payload; 805 /* 806 * Not necessary to update ccid3hcrx_bytes_recv here, 807 * since X_recv = 0 for the first feedback packet (cf. 808 * RFC 3448, 6.3) -- gerrit 809 */ 810 } 811 goto update_records; 812 } 813 814 if (tfrc_rx_hist_duplicate(&hcrx->ccid3hcrx_hist, skb)) 815 return; /* done receiving */ 816 817 if (is_data_packet) { 818 const u32 payload = skb->len - dccp_hdr(skb)->dccph_doff * 4; 819 /* 820 * Update moving-average of s and the sum of received payload bytes 821 */ 822 hcrx->ccid3hcrx_s = tfrc_ewma(hcrx->ccid3hcrx_s, payload, 9); 823 hcrx->ccid3hcrx_bytes_recv += payload; 824 } 825 826 /* 827 * Handle pending losses and otherwise check for new loss 828 */ 829 if (tfrc_rx_hist_loss_pending(&hcrx->ccid3hcrx_hist) && 830 tfrc_rx_handle_loss(&hcrx->ccid3hcrx_hist, 831 &hcrx->ccid3hcrx_li_hist, 832 skb, ndp, ccid3_first_li, sk) ) { 833 do_feedback = CCID3_FBACK_PARAM_CHANGE; 834 goto done_receiving; 835 } 836 837 if (tfrc_rx_hist_new_loss_indicated(&hcrx->ccid3hcrx_hist, skb, ndp)) 838 goto update_records; 839 840 /* 841 * Handle data packets: RTT sampling and monitoring p 842 */ 843 if (unlikely(!is_data_packet)) 844 goto update_records; 845 846 if (!tfrc_lh_is_initialised(&hcrx->ccid3hcrx_li_hist)) { 847 const u32 sample = tfrc_rx_hist_sample_rtt(&hcrx->ccid3hcrx_hist, skb); 848 /* 849 * Empty loss history: no loss so far, hence p stays 0. 850 * Sample RTT values, since an RTT estimate is required for the 851 * computation of p when the first loss occurs; RFC 3448, 6.3.1. 852 */ 853 if (sample != 0) 854 hcrx->ccid3hcrx_rtt = tfrc_ewma(hcrx->ccid3hcrx_rtt, sample, 9); 855 856 } else if (tfrc_lh_update_i_mean(&hcrx->ccid3hcrx_li_hist, skb)) { 857 /* 858 * Step (3) of [RFC 3448, 6.1]: Recompute I_mean and, if I_mean 859 * has decreased (resp. p has increased), send feedback now. 860 */ 861 do_feedback = CCID3_FBACK_PARAM_CHANGE; 862 } 863 864 /* 865 * Check if the periodic once-per-RTT feedback is due; RFC 4342, 10.3 866 */ 867 if (SUB16(dccp_hdr(skb)->dccph_ccval, hcrx->ccid3hcrx_last_counter) > 3) 868 do_feedback = CCID3_FBACK_PERIODIC; 869 870 update_records: 871 tfrc_rx_hist_add_packet(&hcrx->ccid3hcrx_hist, skb, ndp); 872 873 done_receiving: 874 if (do_feedback) 875 ccid3_hc_rx_send_feedback(sk, skb, do_feedback); 876 } 877 878 static int ccid3_hc_rx_init(struct ccid *ccid, struct sock *sk) 879 { 880 struct ccid3_hc_rx_sock *hcrx = ccid_priv(ccid); 881 882 hcrx->ccid3hcrx_state = TFRC_RSTATE_NO_DATA; 883 tfrc_lh_init(&hcrx->ccid3hcrx_li_hist); 884 return tfrc_rx_hist_alloc(&hcrx->ccid3hcrx_hist); 885 } 886 887 static void ccid3_hc_rx_exit(struct sock *sk) 888 { 889 struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk); 890 891 ccid3_hc_rx_set_state(sk, TFRC_RSTATE_TERM); 892 893 tfrc_rx_hist_purge(&hcrx->ccid3hcrx_hist); 894 tfrc_lh_cleanup(&hcrx->ccid3hcrx_li_hist); 895 } 896 897 static void ccid3_hc_rx_get_info(struct sock *sk, struct tcp_info *info) 898 { 899 const struct ccid3_hc_rx_sock *hcrx; 900 901 /* Listen socks doesn't have a private CCID block */ 902 if (sk->sk_state == DCCP_LISTEN) 903 return; 904 905 hcrx = ccid3_hc_rx_sk(sk); 906 info->tcpi_ca_state = hcrx->ccid3hcrx_state; 907 info->tcpi_options |= TCPI_OPT_TIMESTAMPS; 908 info->tcpi_rcv_rtt = hcrx->ccid3hcrx_rtt; 909 } 910 911 static int ccid3_hc_rx_getsockopt(struct sock *sk, const int optname, int len, 912 u32 __user *optval, int __user *optlen) 913 { 914 const struct ccid3_hc_rx_sock *hcrx; 915 struct tfrc_rx_info rx_info; 916 const void *val; 917 918 /* Listen socks doesn't have a private CCID block */ 919 if (sk->sk_state == DCCP_LISTEN) 920 return -EINVAL; 921 922 hcrx = ccid3_hc_rx_sk(sk); 923 switch (optname) { 924 case DCCP_SOCKOPT_CCID_RX_INFO: 925 if (len < sizeof(rx_info)) 926 return -EINVAL; 927 rx_info.tfrcrx_x_recv = hcrx->ccid3hcrx_x_recv; 928 rx_info.tfrcrx_rtt = hcrx->ccid3hcrx_rtt; 929 rx_info.tfrcrx_p = hcrx->ccid3hcrx_pinv == 0 ? ~0U : 930 scaled_div(1, hcrx->ccid3hcrx_pinv); 931 len = sizeof(rx_info); 932 val = &rx_info; 933 break; 934 default: 935 return -ENOPROTOOPT; 936 } 937 938 if (put_user(len, optlen) || copy_to_user(optval, val, len)) 939 return -EFAULT; 940 941 return 0; 942 } 943 944 static struct ccid_operations ccid3 = { 945 .ccid_id = DCCPC_CCID3, 946 .ccid_name = "TCP-Friendly Rate Control", 947 .ccid_owner = THIS_MODULE, 948 .ccid_hc_tx_obj_size = sizeof(struct ccid3_hc_tx_sock), 949 .ccid_hc_tx_init = ccid3_hc_tx_init, 950 .ccid_hc_tx_exit = ccid3_hc_tx_exit, 951 .ccid_hc_tx_send_packet = ccid3_hc_tx_send_packet, 952 .ccid_hc_tx_packet_sent = ccid3_hc_tx_packet_sent, 953 .ccid_hc_tx_packet_recv = ccid3_hc_tx_packet_recv, 954 .ccid_hc_tx_parse_options = ccid3_hc_tx_parse_options, 955 .ccid_hc_rx_obj_size = sizeof(struct ccid3_hc_rx_sock), 956 .ccid_hc_rx_init = ccid3_hc_rx_init, 957 .ccid_hc_rx_exit = ccid3_hc_rx_exit, 958 .ccid_hc_rx_insert_options = ccid3_hc_rx_insert_options, 959 .ccid_hc_rx_packet_recv = ccid3_hc_rx_packet_recv, 960 .ccid_hc_rx_get_info = ccid3_hc_rx_get_info, 961 .ccid_hc_tx_get_info = ccid3_hc_tx_get_info, 962 .ccid_hc_rx_getsockopt = ccid3_hc_rx_getsockopt, 963 .ccid_hc_tx_getsockopt = ccid3_hc_tx_getsockopt, 964 }; 965 966 #ifdef CONFIG_IP_DCCP_CCID3_DEBUG 967 module_param(ccid3_debug, bool, 0444); 968 MODULE_PARM_DESC(ccid3_debug, "Enable debug messages"); 969 #endif 970 971 static __init int ccid3_module_init(void) 972 { 973 return ccid_register(&ccid3); 974 } 975 module_init(ccid3_module_init); 976 977 static __exit void ccid3_module_exit(void) 978 { 979 ccid_unregister(&ccid3); 980 } 981 module_exit(ccid3_module_exit); 982 983 MODULE_AUTHOR("Ian McDonald <ian.mcdonald@jandi.co.nz>, " 984 "Arnaldo Carvalho de Melo <acme@ghostprotocols.net>"); 985 MODULE_DESCRIPTION("DCCP TFRC CCID3 CCID"); 986 MODULE_LICENSE("GPL"); 987 MODULE_ALIAS("net-dccp-ccid-3"); 988