net/dccp/ccids/ccid3.c

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

DEFINITIONS
