// SPDX-License-Identifier: GPL-2.0-or-later /* * Copyright (c) 2007 The University of Aberdeen, Scotland, UK * Copyright (c) 2005-7 The University of Waikato, Hamilton, New Zealand. * Copyright (c) 2005-7 Ian McDonald <ian.mcdonald@jandi.co.nz> * * An implementation of the DCCP protocol * * This code has been developed by the University of Waikato WAND * research group. For further information please see https://www.wand.net.nz/ * * This code also uses code from Lulea University, rereleased as GPL by its * authors: * Copyright (c) 2003 Nils-Erik Mattsson, Joacim Haggmark, Magnus Erixzon * * Changes to meet Linux coding standards, to make it meet latest ccid3 draft * and to make it work as a loadable module in the DCCP stack written by * Arnaldo Carvalho de Melo <acme@conectiva.com.br>. * * Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@conectiva.com.br> */ #include "../dccp.h" #include "ccid3.h" #include <asm/unaligned.h> #ifdef CONFIG_IP_DCCP_CCID3_DEBUG static bool ccid3_debug; #define ccid3_pr_debug(format, a...) DCCP_PR_DEBUG(ccid3_debug, format, ##a) #else #define ccid3_pr_debug(format, a...) #endif /* * Transmitter Half-Connection Routines */ #ifdef CONFIG_IP_DCCP_CCID3_DEBUG static const char *ccid3_tx_state_name(enum ccid3_hc_tx_states state) { static const char *const ccid3_state_names[] = { [TFRC_SSTATE_NO_SENT] = "NO_SENT", [TFRC_SSTATE_NO_FBACK] = "NO_FBACK", [TFRC_SSTATE_FBACK] = "FBACK", }; return ccid3_state_names[state]; } #endif static void ccid3_hc_tx_set_state(struct sock *sk, enum ccid3_hc_tx_states state) { struct ccid3_hc_tx_sock *hc = ccid3_hc_tx_sk(sk); enum ccid3_hc_tx_states oldstate = hc->tx_state; ccid3_pr_debug("%s(%p) %-8.8s -> %s\n", dccp_role(sk), sk, ccid3_tx_state_name(oldstate), ccid3_tx_state_name(state)); WARN_ON(state == oldstate); hc->tx_state = state; } /* * Compute the initial sending rate X_init in the manner of RFC 3390: * * X_init = min(4 * s, max(2 * s, 4380 bytes)) / RTT * * Note that RFC 3390 uses MSS, RFC 4342 refers to RFC 3390, and rfc3448bis * (rev-02) clarifies the use of RFC 3390 with regard to the above formula. * For consistency with other parts of the code, X_init is scaled by 2^6. */ static inline u64 rfc3390_initial_rate(struct sock *sk) { const struct ccid3_hc_tx_sock *hc = ccid3_hc_tx_sk(sk); const __u32 w_init = clamp_t(__u32, 4380U, 2 * hc->tx_s, 4 * hc->tx_s); return scaled_div(w_init << 6, hc->tx_rtt); } /** * ccid3_update_send_interval - Calculate new t_ipi = s / X_inst * @hc: socket to have the send interval updated * * This respects the granularity of X_inst (64 * bytes/second). */ static void ccid3_update_send_interval(struct ccid3_hc_tx_sock *hc) { hc->tx_t_ipi = scaled_div32(((u64)hc->tx_s) << 6, hc->tx_x); DCCP_BUG_ON(hc->tx_t_ipi == 0); ccid3_pr_debug("t_ipi=%u, s=%u, X=%u\n", hc->tx_t_ipi, hc->tx_s, (unsigned int)(hc->tx_x >> 6)); } static u32 ccid3_hc_tx_idle_rtt(struct ccid3_hc_tx_sock *hc, ktime_t now) { u32 delta = ktime_us_delta(now, hc->tx_t_last_win_count); return delta / hc->tx_rtt; } /** * ccid3_hc_tx_update_x - Update allowed sending rate X * @sk: socket to be updated * @stamp: most recent time if available - can be left NULL. * * This function tracks draft rfc3448bis, check there for latest details. * * Note: X and X_recv are both stored in units of 64 * bytes/second, to support * fine-grained resolution of sending rates. This requires scaling by 2^6 * throughout the code. Only X_calc is unscaled (in bytes/second). * */ static void ccid3_hc_tx_update_x(struct sock *sk, ktime_t *stamp) { struct ccid3_hc_tx_sock *hc = ccid3_hc_tx_sk(sk); __u64 min_rate = 2 * hc->tx_x_recv; const __u64 old_x = hc->tx_x; ktime_t now = stamp ? *stamp : ktime_get_real(); /* * Handle IDLE periods: do not reduce below RFC3390 initial sending rate * when idling [RFC 4342, 5.1]. Definition of idling is from rfc3448bis: * a sender is idle if it has not sent anything over a 2-RTT-period. * For consistency with X and X_recv, min_rate is also scaled by 2^6. */ if (ccid3_hc_tx_idle_rtt(hc, now) >= 2) { min_rate = rfc3390_initial_rate(sk); min_rate = max(min_rate, 2 * hc->tx_x_recv); } if (hc->tx_p > 0) { hc->tx_x = min(((__u64)hc->tx_x_calc) << 6, min_rate); hc->tx_x = max(hc->tx_x, (((__u64)hc->tx_s) << 6) / TFRC_T_MBI); } else if (ktime_us_delta(now, hc->tx_t_ld) - (s64)hc->tx_rtt >= 0) { hc->tx_x = min(2 * hc->tx_x, min_rate); hc->tx_x = max(hc->tx_x, scaled_div(((__u64)hc->tx_s) << 6, hc->tx_rtt)); hc->tx_t_ld = now; } if (hc->tx_x != old_x) { ccid3_pr_debug("X_prev=%u, X_now=%u, X_calc=%u, " "X_recv=%u\n", (unsigned int)(old_x >> 6), (unsigned int)(hc->tx_x >> 6), hc->tx_x_calc, (unsigned int)(hc->tx_x_recv >> 6)); ccid3_update_send_interval(hc); } } /** * ccid3_hc_tx_update_s - Track the mean packet size `s' * @hc: socket to be updated * @len: DCCP packet payload size in bytes * * cf. RFC 4342, 5.3 and RFC 3448, 4.1 */ static inline void ccid3_hc_tx_update_s(struct ccid3_hc_tx_sock *hc, int len) { const u16 old_s = hc->tx_s; hc->tx_s = tfrc_ewma(hc->tx_s, len, 9); if (hc->tx_s != old_s) ccid3_update_send_interval(hc); } /* * Update Window Counter using the algorithm from [RFC 4342, 8.1]. * As elsewhere, RTT > 0 is assumed by using dccp_sample_rtt(). */ static inline void ccid3_hc_tx_update_win_count(struct ccid3_hc_tx_sock *hc, ktime_t now) { u32 delta = ktime_us_delta(now, hc->tx_t_last_win_count), quarter_rtts = (4 * delta) / hc->tx_rtt; if (quarter_rtts > 0) { hc->tx_t_last_win_count = now; hc->tx_last_win_count += min(quarter_rtts, 5U); hc->tx_last_win_count &= 0xF; /* mod 16 */ } } static void ccid3_hc_tx_no_feedback_timer(struct timer_list *t) { struct ccid3_hc_tx_sock *hc = from_timer(hc, t, tx_no_feedback_timer); struct sock *sk = hc->sk; unsigned long t_nfb = USEC_PER_SEC / 5; bh_lock_sock(sk); if (sock_owned_by_user(sk)) { /* Try again later. */ /* XXX: set some sensible MIB */ goto restart_timer; } ccid3_pr_debug("%s(%p, state=%s) - entry\n", dccp_role(sk), sk, ccid3_tx_state_name(hc->tx_state)); /* Ignore and do not restart after leaving the established state */ if ((1 << sk->sk_state) & ~(DCCPF_OPEN | DCCPF_PARTOPEN)) goto out; /* Reset feedback state to "no feedback received" */ if (hc->tx_state == TFRC_SSTATE_FBACK) ccid3_hc_tx_set_state(sk, TFRC_SSTATE_NO_FBACK); /* * Determine new allowed sending rate X as per draft rfc3448bis-00, 4.4 * RTO is 0 if and only if no feedback has been received yet. */ if (hc->tx_t_rto == 0 || hc->tx_p == 0) { /* halve send rate directly */ hc->tx_x = max(hc->tx_x / 2, (((__u64)hc->tx_s) << 6) / TFRC_T_MBI); ccid3_update_send_interval(hc); } else { /* * Modify the cached value of X_recv * * If (X_calc > 2 * X_recv) * X_recv = max(X_recv / 2, s / (2 * t_mbi)); * Else * X_recv = X_calc / 4; * * Note that X_recv is scaled by 2^6 while X_calc is not */ if (hc->tx_x_calc > (hc->tx_x_recv >> 5)) hc->tx_x_recv = max(hc->tx_x_recv / 2, (((__u64)hc->tx_s) << 6) / (2*TFRC_T_MBI)); else { hc->tx_x_recv = hc->tx_x_calc; hc->tx_x_recv <<= 4; } ccid3_hc_tx_update_x(sk, NULL); } ccid3_pr_debug("Reduced X to %llu/64 bytes/sec\n", (unsigned long long)hc->tx_x); /* * Set new timeout for the nofeedback timer. * See comments in packet_recv() regarding the value of t_RTO. */ if (unlikely(hc->tx_t_rto == 0)) /* no feedback received yet */ t_nfb = TFRC_INITIAL_TIMEOUT; else t_nfb = max(hc->tx_t_rto, 2 * hc->tx_t_ipi); restart_timer: sk_reset_timer(sk, &hc->tx_no_feedback_timer, jiffies + usecs_to_jiffies(t_nfb)); out: bh_unlock_sock(sk); sock_put(sk); } /** * ccid3_hc_tx_send_packet - Delay-based dequeueing of TX packets * @sk: socket to send packet from * @skb: next packet candidate to send on @sk * * This function uses the convention of ccid_packet_dequeue_eval() and * returns a millisecond-delay value between 0 and t_mbi = 64000 msec. */ static int ccid3_hc_tx_send_packet(struct sock *sk, struct sk_buff *skb) { struct dccp_sock *dp = dccp_sk(sk); struct ccid3_hc_tx_sock *hc = ccid3_hc_tx_sk(sk); ktime_t now = ktime_get_real(); s64 delay; /* * This function is called only for Data and DataAck packets. Sending * zero-sized Data(Ack)s is theoretically possible, but for congestion * control this case is pathological - ignore it. */ if (unlikely(skb->len == 0)) return -EBADMSG; if (hc->tx_state == TFRC_SSTATE_NO_SENT) { sk_reset_timer(sk, &hc->tx_no_feedback_timer, (jiffies + usecs_to_jiffies(TFRC_INITIAL_TIMEOUT))); hc->tx_last_win_count = 0; hc->tx_t_last_win_count = now; /* Set t_0 for initial packet */ hc->tx_t_nom = now; hc->tx_s = skb->len; /* * Use initial RTT sample when available: recommended by erratum * to RFC 4342. This implements the initialisation procedure of * draft rfc3448bis, section 4.2. Remember, X is scaled by 2^6. */ if (dp->dccps_syn_rtt) { ccid3_pr_debug("SYN RTT = %uus\n", dp->dccps_syn_rtt); hc->tx_rtt = dp->dccps_syn_rtt; hc->tx_x = rfc3390_initial_rate(sk); hc->tx_t_ld = now; } else { /* * Sender does not have RTT sample: * - set fallback RTT (RFC 4340, 3.4) since a RTT value * is needed in several parts (e.g. window counter); * - set sending rate X_pps = 1pps as per RFC 3448, 4.2. */ hc->tx_rtt = DCCP_FALLBACK_RTT; hc->tx_x = hc->tx_s; hc->tx_x <<= 6; } ccid3_update_send_interval(hc); ccid3_hc_tx_set_state(sk, TFRC_SSTATE_NO_FBACK); } else { delay = ktime_us_delta(hc->tx_t_nom, now); ccid3_pr_debug("delay=%ld\n", (long)delay); /* * Scheduling of packet transmissions (RFC 5348, 8.3) * * if (t_now > t_nom - delta) * // send the packet now * else * // send the packet in (t_nom - t_now) milliseconds. */ if (delay >= TFRC_T_DELTA) return (u32)delay / USEC_PER_MSEC; ccid3_hc_tx_update_win_count(hc, now); } /* prepare to send now (add options etc.) */ dp->dccps_hc_tx_insert_options = 1; DCCP_SKB_CB(skb)->dccpd_ccval = hc->tx_last_win_count; /* set the nominal send time for the next following packet */ hc->tx_t_nom = ktime_add_us(hc->tx_t_nom, hc->tx_t_ipi); return CCID_PACKET_SEND_AT_ONCE; } static void ccid3_hc_tx_packet_sent(struct sock *sk, unsigned int len) { struct ccid3_hc_tx_sock *hc = ccid3_hc_tx_sk(sk); ccid3_hc_tx_update_s(hc, len); if (tfrc_tx_hist_add(&hc->tx_hist, dccp_sk(sk)->dccps_gss)) DCCP_CRIT("packet history - out of memory!"); } static void ccid3_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb) { struct ccid3_hc_tx_sock *hc = ccid3_hc_tx_sk(sk); struct tfrc_tx_hist_entry *acked; ktime_t now; unsigned long t_nfb; u32 r_sample; /* we are only interested in ACKs */ if (!(DCCP_SKB_CB(skb)->dccpd_type == DCCP_PKT_ACK || DCCP_SKB_CB(skb)->dccpd_type == DCCP_PKT_DATAACK)) return; /* * Locate the acknowledged packet in the TX history. * * Returning "entry not found" here can for instance happen when * - the host has not sent out anything (e.g. a passive server), * - the Ack is outdated (packet with higher Ack number was received), * - it is a bogus Ack (for a packet not sent on this connection). */ acked = tfrc_tx_hist_find_entry(hc->tx_hist, dccp_hdr_ack_seq(skb)); if (acked == NULL) return; /* For the sake of RTT sampling, ignore/remove all older entries */ tfrc_tx_hist_purge(&acked->next); /* Update the moving average for the RTT estimate (RFC 3448, 4.3) */ now = ktime_get_real(); r_sample = dccp_sample_rtt(sk, ktime_us_delta(now, acked->stamp)); hc->tx_rtt = tfrc_ewma(hc->tx_rtt, r_sample, 9); /* * Update allowed sending rate X as per draft rfc3448bis-00, 4.2/3 */ if (hc->tx_state == TFRC_SSTATE_NO_FBACK) { ccid3_hc_tx_set_state(sk, TFRC_SSTATE_FBACK); if (hc->tx_t_rto == 0) { /* * Initial feedback packet: Larger Initial Windows (4.2) */ hc->tx_x = rfc3390_initial_rate(sk); hc->tx_t_ld = now; ccid3_update_send_interval(hc); goto done_computing_x; } else if (hc->tx_p == 0) { /* * First feedback after nofeedback timer expiry (4.3) */ goto done_computing_x; } } /* Update sending rate (step 4 of [RFC 3448, 4.3]) */ if (hc->tx_p > 0) hc->tx_x_calc = tfrc_calc_x(hc->tx_s, hc->tx_rtt, hc->tx_p); ccid3_hc_tx_update_x(sk, &now); done_computing_x: ccid3_pr_debug("%s(%p), RTT=%uus (sample=%uus), s=%u, " "p=%u, X_calc=%u, X_recv=%u, X=%u\n", dccp_role(sk), sk, hc->tx_rtt, r_sample, hc->tx_s, hc->tx_p, hc->tx_x_calc, (unsigned int)(hc->tx_x_recv >> 6), (unsigned int)(hc->tx_x >> 6)); /* unschedule no feedback timer */ sk_stop_timer(sk, &hc->tx_no_feedback_timer); /* * As we have calculated new ipi, delta, t_nom it is possible * that we now can send a packet, so wake up dccp_wait_for_ccid */ sk->sk_write_space(sk); /* * Update timeout interval for the nofeedback timer. In order to control * rate halving on networks with very low RTTs (<= 1 ms), use per-route * tunable RTAX_RTO_MIN value as the lower bound. */ hc->tx_t_rto = max_t(u32, 4 * hc->tx_rtt, USEC_PER_SEC/HZ * tcp_rto_min(sk)); /* * Schedule no feedback timer to expire in * max(t_RTO, 2 * s/X) = max(t_RTO, 2 * t_ipi) */ t_nfb = max(hc->tx_t_rto, 2 * hc->tx_t_ipi); ccid3_pr_debug("%s(%p), Scheduled no feedback timer to " "expire in %lu jiffies (%luus)\n", dccp_role(sk), sk, usecs_to_jiffies(t_nfb), t_nfb); sk_reset_timer(sk, &hc->tx_no_feedback_timer, jiffies + usecs_to_jiffies(t_nfb)); } static int ccid3_hc_tx_parse_options(struct sock *sk, u8 packet_type, u8 option, u8 *optval, u8 optlen) { struct ccid3_hc_tx_sock *hc = ccid3_hc_tx_sk(sk); __be32 opt_val; switch (option) { case TFRC_OPT_RECEIVE_RATE: case TFRC_OPT_LOSS_EVENT_RATE: /* Must be ignored on Data packets, cf. RFC 4342 8.3 and 8.5 */ if (packet_type == DCCP_PKT_DATA) break; if (unlikely(optlen != 4)) { DCCP_WARN("%s(%p), invalid len %d for %u\n", dccp_role(sk), sk, optlen, option); return -EINVAL; } opt_val = ntohl(get_unaligned((__be32 *)optval)); if (option == TFRC_OPT_RECEIVE_RATE) { /* Receive Rate is kept in units of 64 bytes/second */ hc->tx_x_recv = opt_val; hc->tx_x_recv <<= 6; ccid3_pr_debug("%s(%p), RECEIVE_RATE=%u\n", dccp_role(sk), sk, opt_val); } else { /* Update the fixpoint Loss Event Rate fraction */ hc->tx_p = tfrc_invert_loss_event_rate(opt_val); ccid3_pr_debug("%s(%p), LOSS_EVENT_RATE=%u\n", dccp_role(sk), sk, opt_val); } } return 0; } static int ccid3_hc_tx_init(struct ccid *ccid, struct sock *sk) { struct ccid3_hc_tx_sock *hc = ccid_priv(ccid); hc->tx_state = TFRC_SSTATE_NO_SENT; hc->tx_hist = NULL; hc->sk = sk; timer_setup(&hc->tx_no_feedback_timer, ccid3_hc_tx_no_feedback_timer, 0); return 0; } static void ccid3_hc_tx_exit(struct sock *sk) { struct ccid3_hc_tx_sock *hc = ccid3_hc_tx_sk(sk); sk_stop_timer(sk, &hc->tx_no_feedback_timer); tfrc_tx_hist_purge(&hc->tx_hist); } static void ccid3_hc_tx_get_info(struct sock *sk, struct tcp_info *info) { info->tcpi_rto = ccid3_hc_tx_sk(sk)->tx_t_rto; info->tcpi_rtt = ccid3_hc_tx_sk(sk)->tx_rtt; } static int ccid3_hc_tx_getsockopt(struct sock *sk, const int optname, int len, u32 __user *optval, int __user *optlen) { const struct ccid3_hc_tx_sock *hc = ccid3_hc_tx_sk(sk); struct tfrc_tx_info tfrc; const void *val; switch (optname) { case DCCP_SOCKOPT_CCID_TX_INFO: if (len < sizeof(tfrc)) return -EINVAL; memset(&tfrc, 0, sizeof(tfrc)); tfrc.tfrctx_x = hc->tx_x; tfrc.tfrctx_x_recv = hc->tx_x_recv; tfrc.tfrctx_x_calc = hc->tx_x_calc; tfrc.tfrctx_rtt = hc->tx_rtt; tfrc.tfrctx_p = hc->tx_p; tfrc.tfrctx_rto = hc->tx_t_rto; tfrc.tfrctx_ipi = hc->tx_t_ipi; len = sizeof(tfrc); val = &tfrc; break; default: return -ENOPROTOOPT; } if (put_user(len, optlen) || copy_to_user(optval, val, len)) return -EFAULT; return 0; } /* * Receiver Half-Connection Routines */ /* CCID3 feedback types */ enum ccid3_fback_type { CCID3_FBACK_NONE = 0, CCID3_FBACK_INITIAL, CCID3_FBACK_PERIODIC, CCID3_FBACK_PARAM_CHANGE }; #ifdef CONFIG_IP_DCCP_CCID3_DEBUG static const char *ccid3_rx_state_name(enum ccid3_hc_rx_states state) { static const char *const ccid3_rx_state_names[] = { [TFRC_RSTATE_NO_DATA] = "NO_DATA", [TFRC_RSTATE_DATA] = "DATA", }; return ccid3_rx_state_names[state]; } #endif static void ccid3_hc_rx_set_state(struct sock *sk, enum ccid3_hc_rx_states state) { struct ccid3_hc_rx_sock *hc = ccid3_hc_rx_sk(sk); enum ccid3_hc_rx_states oldstate = hc->rx_state; ccid3_pr_debug("%s(%p) %-8.8s -> %s\n", dccp_role(sk), sk, ccid3_rx_state_name(oldstate), ccid3_rx_state_name(state)); WARN_ON(state == oldstate); hc->rx_state = state; } static void ccid3_hc_rx_send_feedback(struct sock *sk, const struct sk_buff *skb, enum ccid3_fback_type fbtype) { struct ccid3_hc_rx_sock *hc = ccid3_hc_rx_sk(sk); struct dccp_sock *dp = dccp_sk(sk); ktime_t now = ktime_get(); s64 delta = 0; switch (fbtype) { case CCID3_FBACK_INITIAL: hc->rx_x_recv = 0; hc->rx_pinv = ~0U; /* see RFC 4342, 8.5 */ break; case CCID3_FBACK_PARAM_CHANGE: /* * When parameters change (new loss or p > p_prev), we do not * have a reliable estimate for R_m of [RFC 3448, 6.2] and so * need to reuse the previous value of X_recv. However, when * X_recv was 0 (due to early loss), this would kill X down to * s/t_mbi (i.e. one packet in 64 seconds). * To avoid such drastic reduction, we approximate X_recv as * the number of bytes since last feedback. * This is a safe fallback, since X is bounded above by X_calc. */ if (hc->rx_x_recv > 0) break; fallthrough; case CCID3_FBACK_PERIODIC: delta = ktime_us_delta(now, hc->rx_tstamp_last_feedback); if (delta <= 0) delta = 1; hc->rx_x_recv = scaled_div32(hc->rx_bytes_recv, delta); break; default: return; } ccid3_pr_debug("Interval %lldusec, X_recv=%u, 1/p=%u\n", delta, hc->rx_x_recv, hc->rx_pinv); hc->rx_tstamp_last_feedback = now; hc->rx_last_counter = dccp_hdr(skb)->dccph_ccval; hc->rx_bytes_recv = 0; dp->dccps_hc_rx_insert_options = 1; dccp_send_ack(sk); } static int ccid3_hc_rx_insert_options(struct sock *sk, struct sk_buff *skb) { const struct ccid3_hc_rx_sock *hc = ccid3_hc_rx_sk(sk); __be32 x_recv, pinv; if (!(sk->sk_state == DCCP_OPEN || sk->sk_state == DCCP_PARTOPEN)) return 0; if (dccp_packet_without_ack(skb)) return 0; x_recv = htonl(hc->rx_x_recv); pinv = htonl(hc->rx_pinv); if (dccp_insert_option(skb, TFRC_OPT_LOSS_EVENT_RATE, &pinv, sizeof(pinv)) || dccp_insert_option(skb, TFRC_OPT_RECEIVE_RATE, &x_recv, sizeof(x_recv))) return -1; return 0; } /** * ccid3_first_li - Implements [RFC 5348, 6.3.1] * @sk: socket to calculate loss interval for * * Determine the length of the first loss interval via inverse lookup. * Assume that X_recv can be computed by the throughput equation * s * X_recv = -------- * R * fval * Find some p such that f(p) = fval; return 1/p (scaled). */ static u32 ccid3_first_li(struct sock *sk) { struct ccid3_hc_rx_sock *hc = ccid3_hc_rx_sk(sk); u32 x_recv, p; s64 delta; u64 fval; if (hc->rx_rtt == 0) { DCCP_WARN("No RTT estimate available, using fallback RTT\n"); hc->rx_rtt = DCCP_FALLBACK_RTT; } delta = ktime_us_delta(ktime_get(), hc->rx_tstamp_last_feedback); if (delta <= 0) delta = 1; x_recv = scaled_div32(hc->rx_bytes_recv, delta); if (x_recv == 0) { /* would also trigger divide-by-zero */ DCCP_WARN("X_recv==0\n"); if (hc->rx_x_recv == 0) { DCCP_BUG("stored value of X_recv is zero"); return ~0U; } x_recv = hc->rx_x_recv; } fval = scaled_div(hc->rx_s, hc->rx_rtt); fval = scaled_div32(fval, x_recv); p = tfrc_calc_x_reverse_lookup(fval); ccid3_pr_debug("%s(%p), receive rate=%u bytes/s, implied " "loss rate=%u\n", dccp_role(sk), sk, x_recv, p); return p == 0 ? ~0U : scaled_div(1, p); } static void ccid3_hc_rx_packet_recv(struct sock *sk, struct sk_buff *skb) { struct ccid3_hc_rx_sock *hc = ccid3_hc_rx_sk(sk); enum ccid3_fback_type do_feedback = CCID3_FBACK_NONE; const u64 ndp = dccp_sk(sk)->dccps_options_received.dccpor_ndp; const bool is_data_packet = dccp_data_packet(skb); if (unlikely(hc->rx_state == TFRC_RSTATE_NO_DATA)) { if (is_data_packet) { const u32 payload = skb->len - dccp_hdr(skb)->dccph_doff * 4; do_feedback = CCID3_FBACK_INITIAL; ccid3_hc_rx_set_state(sk, TFRC_RSTATE_DATA); hc->rx_s = payload; /* * Not necessary to update rx_bytes_recv here, * since X_recv = 0 for the first feedback packet (cf. * RFC 3448, 6.3) -- gerrit */ } goto update_records; } if (tfrc_rx_hist_duplicate(&hc->rx_hist, skb)) return; /* done receiving */ if (is_data_packet) { const u32 payload = skb->len - dccp_hdr(skb)->dccph_doff * 4; /* * Update moving-average of s and the sum of received payload bytes */ hc->rx_s = tfrc_ewma(hc->rx_s, payload, 9); hc->rx_bytes_recv += payload; } /* * Perform loss detection and handle pending losses */ if (tfrc_rx_handle_loss(&hc->rx_hist, &hc->rx_li_hist, skb, ndp, ccid3_first_li, sk)) { do_feedback = CCID3_FBACK_PARAM_CHANGE; goto done_receiving; } if (tfrc_rx_hist_loss_pending(&hc->rx_hist)) return; /* done receiving */ /* * Handle data packets: RTT sampling and monitoring p */ if (unlikely(!is_data_packet)) goto update_records; if (!tfrc_lh_is_initialised(&hc->rx_li_hist)) { const u32 sample = tfrc_rx_hist_sample_rtt(&hc->rx_hist, skb); /* * Empty loss history: no loss so far, hence p stays 0. * Sample RTT values, since an RTT estimate is required for the * computation of p when the first loss occurs; RFC 3448, 6.3.1. */ if (sample != 0) hc->rx_rtt = tfrc_ewma(hc->rx_rtt, sample, 9); } else if (tfrc_lh_update_i_mean(&hc->rx_li_hist, skb)) { /* * Step (3) of [RFC 3448, 6.1]: Recompute I_mean and, if I_mean * has decreased (resp. p has increased), send feedback now. */ do_feedback = CCID3_FBACK_PARAM_CHANGE; } /* * Check if the periodic once-per-RTT feedback is due; RFC 4342, 10.3 */ if (SUB16(dccp_hdr(skb)->dccph_ccval, hc->rx_last_counter) > 3) do_feedback = CCID3_FBACK_PERIODIC; update_records: tfrc_rx_hist_add_packet(&hc->rx_hist, skb, ndp); done_receiving: if (do_feedback) ccid3_hc_rx_send_feedback(sk, skb, do_feedback); } static int ccid3_hc_rx_init(struct ccid *ccid, struct sock *sk) { struct ccid3_hc_rx_sock *hc = ccid_priv(ccid); hc->rx_state = TFRC_RSTATE_NO_DATA; tfrc_lh_init(&hc->rx_li_hist); return tfrc_rx_hist_alloc(&hc->rx_hist); } static void ccid3_hc_rx_exit(struct sock *sk) { struct ccid3_hc_rx_sock *hc = ccid3_hc_rx_sk(sk); tfrc_rx_hist_purge(&hc->rx_hist); tfrc_lh_cleanup(&hc->rx_li_hist); } static void ccid3_hc_rx_get_info(struct sock *sk, struct tcp_info *info) { info->tcpi_ca_state = ccid3_hc_rx_sk(sk)->rx_state; info->tcpi_options |= TCPI_OPT_TIMESTAMPS; info->tcpi_rcv_rtt = ccid3_hc_rx_sk(sk)->rx_rtt; } static int ccid3_hc_rx_getsockopt(struct sock *sk, const int optname, int len, u32 __user *optval, int __user *optlen) { const struct ccid3_hc_rx_sock *hc = ccid3_hc_rx_sk(sk); struct tfrc_rx_info rx_info; const void *val; switch (optname) { case DCCP_SOCKOPT_CCID_RX_INFO: if (len < sizeof(rx_info)) return -EINVAL; rx_info.tfrcrx_x_recv = hc->rx_x_recv; rx_info.tfrcrx_rtt = hc->rx_rtt; rx_info.tfrcrx_p = tfrc_invert_loss_event_rate(hc->rx_pinv); len = sizeof(rx_info); val = &rx_info; break; default: return -ENOPROTOOPT; } if (put_user(len, optlen) || copy_to_user(optval, val, len)) return -EFAULT; return 0; } struct ccid_operations ccid3_ops = { .ccid_id = DCCPC_CCID3, .ccid_name = "TCP-Friendly Rate Control", .ccid_hc_tx_obj_size = sizeof(struct ccid3_hc_tx_sock), .ccid_hc_tx_init = ccid3_hc_tx_init, .ccid_hc_tx_exit = ccid3_hc_tx_exit, .ccid_hc_tx_send_packet = ccid3_hc_tx_send_packet, .ccid_hc_tx_packet_sent = ccid3_hc_tx_packet_sent, .ccid_hc_tx_packet_recv = ccid3_hc_tx_packet_recv, .ccid_hc_tx_parse_options = ccid3_hc_tx_parse_options, .ccid_hc_rx_obj_size = sizeof(struct ccid3_hc_rx_sock), .ccid_hc_rx_init = ccid3_hc_rx_init, .ccid_hc_rx_exit = ccid3_hc_rx_exit, .ccid_hc_rx_insert_options = ccid3_hc_rx_insert_options, .ccid_hc_rx_packet_recv = ccid3_hc_rx_packet_recv, .ccid_hc_rx_get_info = ccid3_hc_rx_get_info, .ccid_hc_tx_get_info = ccid3_hc_tx_get_info, .ccid_hc_rx_getsockopt = ccid3_hc_rx_getsockopt, .ccid_hc_tx_getsockopt = ccid3_hc_tx_getsockopt, }; #ifdef CONFIG_IP_DCCP_CCID3_DEBUG module_param(ccid3_debug, bool, 0644); MODULE_PARM_DESC(ccid3_debug, "Enable CCID-3 debug messages"); #endif