diff options
Diffstat (limited to 'net/dccp/ccids/ccid3.c')
| -rw-r--r-- | net/dccp/ccids/ccid3.c | 866 |
1 files changed, 866 insertions, 0 deletions
diff --git a/net/dccp/ccids/ccid3.c b/net/dccp/ccids/ccid3.c new file mode 100644 index 00000000..3d604e13 --- /dev/null +++ b/net/dccp/ccids/ccid3.c @@ -0,0 +1,866 @@ +/* + * 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 http://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> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. + */ +#include "../dccp.h" +#include "ccid3.h" + +#include <asm/unaligned.h> + +#ifdef CONFIG_IP_DCCP_CCID3_DEBUG +static int 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 + * 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); + + ccid3_pr_debug("t_ipi=%u, s=%u, X=%u\n", hc->tx_t_ipi, + hc->tx_s, (unsigned)(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 + * @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)(old_x >> 6), + (unsigned)(hc->tx_x >> 6), hc->tx_x_calc, + (unsigned)(hc->tx_x_recv >> 6)); + + ccid3_update_send_interval(hc); + } +} + +/* + * Track the mean packet size `s' (cf. RFC 4342, 5.3 and RFC 3448, 4.1) + * @len: DCCP packet payload size in bytes + */ +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(unsigned long data) +{ + struct sock *sk = (struct sock *)data; + struct ccid3_hc_tx_sock *hc = ccid3_hc_tx_sk(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 + */ + BUG_ON(hc->tx_p && !hc->tx_x_calc); + + 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 + * @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)(hc->tx_x_recv >> 6), + (unsigned)(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; + setup_timer(&hc->tx_no_feedback_timer, + ccid3_hc_tx_no_feedback_timer, (unsigned long)sk); + 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; + 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_real(); + 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; + /* fall through */ + case CCID3_FBACK_PERIODIC: + delta = ktime_us_delta(now, hc->rx_tstamp_last_feedback); + if (delta <= 0) + DCCP_BUG("delta (%ld) <= 0", (long)delta); + else + hc->rx_x_recv = scaled_div32(hc->rx_bytes_recv, delta); + break; + default: + return; + } + + ccid3_pr_debug("Interval %ldusec, X_recv=%u, 1/p=%u\n", (long)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] + * + * 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, 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_to_us(net_timedelta(hc->rx_tstamp_last_feedback)); + 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 |