--- /dev/null
+/*
+ * 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 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
+ * 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
+ * @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'
+ * @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(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
+ */
+ 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 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;
+ 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;
+ 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_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
Code Review / kvmfornfv.git / blobdiff