Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6

[deliverable/linux.git] / net / dccp / ccids / ccid3.c

/*
 *  net/dccp/ccids/ccid3.c
 *
 *  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 "../ccid.h"
#include "../dccp.h"
#include "lib/packet_history.h"
#include "lib/loss_interval.h"
#include "lib/tfrc.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

static struct dccp_tx_hist *ccid3_tx_hist;
static struct dccp_rx_hist *ccid3_rx_hist;

/*
 *      Transmitter Half-Connection Routines
 */
#ifdef CONFIG_IP_DCCP_CCID3_DEBUG
static const char *ccid3_tx_state_name(enum ccid3_hc_tx_states state)
{
        static char *ccid3_state_names[] = {
        [TFRC_SSTATE_NO_SENT]  = "NO_SENT",
        [TFRC_SSTATE_NO_FBACK] = "NO_FBACK",
        [TFRC_SSTATE_FBACK]    = "FBACK",
        [TFRC_SSTATE_TERM]     = "TERM",
        };

        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 *hctx = ccid3_hc_tx_sk(sk);
        enum ccid3_hc_tx_states oldstate = hctx->ccid3hctx_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);
        hctx->ccid3hctx_state = state;
}

/*
 * Compute the initial sending rate X_init according to RFC 3390:
 *      w_init   =    min(4 * MSS, max(2 * MSS, 4380 bytes))
 *      X_init   =    w_init / RTT
 * 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 dccp_sock *dp = dccp_sk(sk);
        const __u32 w_init = min(4 * dp->dccps_mss_cache,
                                 max(2 * dp->dccps_mss_cache, 4380U));

        return scaled_div(w_init << 6, ccid3_hc_tx_sk(sk)->ccid3hctx_rtt);
}

/*
 * Recalculate t_ipi and delta (should be called whenever X changes)
 */
static inline void ccid3_update_send_interval(struct ccid3_hc_tx_sock *hctx)
{
        /* Calculate new t_ipi = s / X_inst (X_inst is in 64 * bytes/second) */
        hctx->ccid3hctx_t_ipi = scaled_div32(((u64)hctx->ccid3hctx_s) << 6,
                                             hctx->ccid3hctx_x);

        /* Calculate new delta by delta = min(t_ipi / 2, t_gran / 2) */
        hctx->ccid3hctx_delta = min_t(u32, hctx->ccid3hctx_t_ipi / 2,
                                           TFRC_OPSYS_HALF_TIME_GRAN);

        ccid3_pr_debug("t_ipi=%u, delta=%u, s=%u, X=%u\n",
                       hctx->ccid3hctx_t_ipi, hctx->ccid3hctx_delta,
                       hctx->ccid3hctx_s, (unsigned)(hctx->ccid3hctx_x >> 6));

}

/**
 * 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 *hctx = ccid3_hc_tx_sk(sk);
        __u64 min_rate = 2 * hctx->ccid3hctx_x_recv;
        const  __u64 old_x = hctx->ccid3hctx_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]. See also draft-ietf-dccp-rfc3448bis.
         * For consistency with X and X_recv, min_rate is also scaled by 2^6.
         */
        if (unlikely(hctx->ccid3hctx_idle)) {
                min_rate = rfc3390_initial_rate(sk);
                min_rate = max(min_rate, 2 * hctx->ccid3hctx_x_recv);
        }

        if (hctx->ccid3hctx_p > 0) {

                hctx->ccid3hctx_x = min(((__u64)hctx->ccid3hctx_x_calc) << 6,
                                        min_rate);
                hctx->ccid3hctx_x = max(hctx->ccid3hctx_x,
                                        (((__u64)hctx->ccid3hctx_s) << 6) /
                                                                TFRC_T_MBI);

        } else if (ktime_us_delta(now, hctx->ccid3hctx_t_ld)
                                - (s64)hctx->ccid3hctx_rtt >= 0) {

                hctx->ccid3hctx_x =
                        max(min(2 * hctx->ccid3hctx_x, min_rate),
                            scaled_div(((__u64)hctx->ccid3hctx_s) << 6,
                                       hctx->ccid3hctx_rtt));
                hctx->ccid3hctx_t_ld = now;
        }

        if (hctx->ccid3hctx_x != old_x) {
                ccid3_pr_debug("X_prev=%u, X_now=%u, X_calc=%u, "
                               "X_recv=%u\n", (unsigned)(old_x >> 6),
                               (unsigned)(hctx->ccid3hctx_x >> 6),
                               hctx->ccid3hctx_x_calc,
                               (unsigned)(hctx->ccid3hctx_x_recv >> 6));

                ccid3_update_send_interval(hctx);
        }
}

/*
 *      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 *hctx, int len)
{
        const u16 old_s = hctx->ccid3hctx_s;

        hctx->ccid3hctx_s = old_s == 0 ? len : (9 * old_s + len) / 10;

        if (hctx->ccid3hctx_s != old_s)
                ccid3_update_send_interval(hctx);
}

/*
 *      Update Window Counter using the algorithm from [RFC 4342, 8.1].
 *      The algorithm is not applicable if RTT < 4 microseconds.
 */
static inline void ccid3_hc_tx_update_win_count(struct ccid3_hc_tx_sock *hctx,
                                                ktime_t now)
{
        u32 quarter_rtts;

        if (unlikely(hctx->ccid3hctx_rtt < 4))  /* avoid divide-by-zero */
                return;

        quarter_rtts = ktime_us_delta(now, hctx->ccid3hctx_t_last_win_count);
        quarter_rtts /= hctx->ccid3hctx_rtt / 4;

        if (quarter_rtts > 0) {
                hctx->ccid3hctx_t_last_win_count = now;
                hctx->ccid3hctx_last_win_count  += min_t(u32, quarter_rtts, 5);
                hctx->ccid3hctx_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 *hctx = 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(hctx->ccid3hctx_state));

        hctx->ccid3hctx_idle = 1;

        switch (hctx->ccid3hctx_state) {
        case TFRC_SSTATE_NO_FBACK:
                /* RFC 3448, 4.4: Halve send rate directly */
                hctx->ccid3hctx_x = max(hctx->ccid3hctx_x / 2,
                                        (((__u64)hctx->ccid3hctx_s) << 6) /
                                                                    TFRC_T_MBI);

                ccid3_pr_debug("%s(%p, state=%s), updated tx rate to %u "
                               "bytes/s\n", dccp_role(sk), sk,
                               ccid3_tx_state_name(hctx->ccid3hctx_state),
                               (unsigned)(hctx->ccid3hctx_x >> 6));
                /* The value of R is still undefined and so we can not recompute
                 * the timeout value. Keep initial value as per [RFC 4342, 5]. */
                t_nfb = TFRC_INITIAL_TIMEOUT;
                ccid3_update_send_interval(hctx);
                break;
        case TFRC_SSTATE_FBACK:
                /*
                 *  Modify the cached value of X_recv [RFC 3448, 4.4]
                 *
                 *  If (p == 0 || 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(hctx->ccid3hctx_p && !hctx->ccid3hctx_x_calc);

                if (hctx->ccid3hctx_p == 0 ||
                    (hctx->ccid3hctx_x_calc > (hctx->ccid3hctx_x_recv >> 5))) {

                        hctx->ccid3hctx_x_recv =
                                max(hctx->ccid3hctx_x_recv / 2,
                                    (((__u64)hctx->ccid3hctx_s) << 6) /
                                                              (2 * TFRC_T_MBI));
                } else {
                        hctx->ccid3hctx_x_recv = hctx->ccid3hctx_x_calc;
                        hctx->ccid3hctx_x_recv <<= 4;
                }
                /* Now recalculate X [RFC 3448, 4.3, step (4)] */
                ccid3_hc_tx_update_x(sk, NULL);
                /*
                 * Schedule no feedback timer to expire in
                 * max(t_RTO, 2 * s/X)  =  max(t_RTO, 2 * t_ipi)
                 * See comments in packet_recv() regarding the value of t_RTO.
                 */
                t_nfb = max(hctx->ccid3hctx_t_rto, 2 * hctx->ccid3hctx_t_ipi);
                break;
        case TFRC_SSTATE_NO_SENT:
                DCCP_BUG("%s(%p) - Illegal state NO_SENT", dccp_role(sk), sk);
                /* fall through */
        case TFRC_SSTATE_TERM:
                goto out;
        }

restart_timer:
        sk_reset_timer(sk, &hctx->ccid3hctx_no_feedback_timer,
                           jiffies + usecs_to_jiffies(t_nfb));
out:
        bh_unlock_sock(sk);
        sock_put(sk);
}

/*
 * returns
 *   > 0: delay (in msecs) that should pass before actually sending
 *   = 0: can send immediately
 *   < 0: error condition; do not send packet
 */
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 *hctx = 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;

        switch (hctx->ccid3hctx_state) {
        case TFRC_SSTATE_NO_SENT:
                sk_reset_timer(sk, &hctx->ccid3hctx_no_feedback_timer,
                               (jiffies +
                                usecs_to_jiffies(TFRC_INITIAL_TIMEOUT)));
                hctx->ccid3hctx_last_win_count   = 0;
                hctx->ccid3hctx_t_last_win_count = now;

                /* Set t_0 for initial packet */
                hctx->ccid3hctx_t_nom = now;

                hctx->ccid3hctx_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);
                        hctx->ccid3hctx_rtt  = dp->dccps_syn_rtt;
                        hctx->ccid3hctx_x    = rfc3390_initial_rate(sk);
                        hctx->ccid3hctx_t_ld = now;
                } else {
                        /* Sender does not have RTT sample: X = MSS/second */
                        hctx->ccid3hctx_x = dp->dccps_mss_cache;
                        hctx->ccid3hctx_x <<= 6;
                }
                ccid3_update_send_interval(hctx);

                ccid3_hc_tx_set_state(sk, TFRC_SSTATE_NO_FBACK);
                break;
        case TFRC_SSTATE_NO_FBACK:
        case TFRC_SSTATE_FBACK:
                delay = ktime_us_delta(hctx->ccid3hctx_t_nom, now);
                ccid3_pr_debug("delay=%ld\n", (long)delay);
                /*
                 *      Scheduling of packet transmissions [RFC 3448, 4.6]
                 *
                 * if (t_now > t_nom - delta)
                 *       // send the packet now
                 * else
                 *       // send the packet in (t_nom - t_now) milliseconds.
                 */
                if (delay - (s64)hctx->ccid3hctx_delta >= 1000)
                        return (u32)delay / 1000L;

                ccid3_hc_tx_update_win_count(hctx, now);
                break;
        case TFRC_SSTATE_TERM:
                DCCP_BUG("%s(%p) - Illegal state TERM", dccp_role(sk), sk);
                return -EINVAL;
        }

        /* prepare to send now (add options etc.) */
        dp->dccps_hc_tx_insert_options = 1;
        DCCP_SKB_CB(skb)->dccpd_ccval = hctx->ccid3hctx_last_win_count;
        hctx->ccid3hctx_idle = 0;

        /* set the nominal send time for the next following packet */
        hctx->ccid3hctx_t_nom = ktime_add_us(hctx->ccid3hctx_t_nom,
                                             hctx->ccid3hctx_t_ipi);
        return 0;
}

static void ccid3_hc_tx_packet_sent(struct sock *sk, int more,
                                    unsigned int len)
{
        struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
        struct dccp_tx_hist_entry *packet;

        ccid3_hc_tx_update_s(hctx, len);

        packet = dccp_tx_hist_entry_new(ccid3_tx_hist, GFP_ATOMIC);
        if (unlikely(packet == NULL)) {
                DCCP_CRIT("packet history - out of memory!");
                return;
        }
        dccp_tx_hist_add_entry(&hctx->ccid3hctx_hist, packet);

        packet->dccphtx_tstamp = ktime_get_real();
        packet->dccphtx_seqno  = dccp_sk(sk)->dccps_gss;
        packet->dccphtx_rtt    = hctx->ccid3hctx_rtt;
        packet->dccphtx_sent   = 1;
}

static void ccid3_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
{
        struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
        struct ccid3_options_received *opt_recv;
        struct dccp_tx_hist_entry *packet;
        ktime_t now;
        unsigned long t_nfb;
        u32 pinv, 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;

        opt_recv = &hctx->ccid3hctx_options_received;

        switch (hctx->ccid3hctx_state) {
        case TFRC_SSTATE_NO_FBACK:
        case TFRC_SSTATE_FBACK:
                /* get packet from history to look up t_recvdata */
                packet = dccp_tx_hist_find_entry(&hctx->ccid3hctx_hist,
                                              DCCP_SKB_CB(skb)->dccpd_ack_seq);
                if (unlikely(packet == NULL)) {
                        DCCP_WARN("%s(%p), seqno %llu(%s) doesn't exist "
                                  "in history!\n",  dccp_role(sk), sk,
                            (unsigned long long)DCCP_SKB_CB(skb)->dccpd_ack_seq,
                                dccp_packet_name(DCCP_SKB_CB(skb)->dccpd_type));
                        return;
                }

                /* Update receive rate in units of 64 * bytes/second */
                hctx->ccid3hctx_x_recv = opt_recv->ccid3or_receive_rate;
                hctx->ccid3hctx_x_recv <<= 6;

                /* Update loss event rate */
                pinv = opt_recv->ccid3or_loss_event_rate;
                if (pinv == ~0U || pinv == 0)          /* see RFC 4342, 8.5   */
                        hctx->ccid3hctx_p = 0;
                else                                   /* can not exceed 100% */
                        hctx->ccid3hctx_p = 1000000 / pinv;

                now = ktime_get_real();
                /*
                 * Calculate new round trip sample as per [RFC 3448, 4.3] by
                 *      R_sample  =  (now - t_recvdata) - t_elapsed
                 */
                r_sample = dccp_sample_rtt(sk, ktime_us_delta(now, packet->dccphtx_tstamp));

                /*
                 * Update RTT estimate by
                 * If (No feedback recv)
                 *    R = R_sample;
                 * Else
                 *    R = q * R + (1 - q) * R_sample;
                 *
                 * q is a constant, RFC 3448 recomments 0.9
                 */
                if (hctx->ccid3hctx_state == TFRC_SSTATE_NO_FBACK) {
                        /*
                         * Larger Initial Windows [RFC 4342, sec. 5]
                         */
                        hctx->ccid3hctx_rtt  = r_sample;
                        hctx->ccid3hctx_x    = rfc3390_initial_rate(sk);
                        hctx->ccid3hctx_t_ld = now;

                        ccid3_update_send_interval(hctx);

                        ccid3_pr_debug("%s(%p), s=%u, MSS=%u, "
                                       "R_sample=%uus, X=%u\n", dccp_role(sk),
                                       sk, hctx->ccid3hctx_s,
                                       dccp_sk(sk)->dccps_mss_cache, r_sample,
                                       (unsigned)(hctx->ccid3hctx_x >> 6));

                        ccid3_hc_tx_set_state(sk, TFRC_SSTATE_FBACK);
                } else {
                        hctx->ccid3hctx_rtt = (9 * hctx->ccid3hctx_rtt +
                                                   r_sample) / 10;

                        /* Update sending rate (step 4 of [RFC 3448, 4.3]) */
                        if (hctx->ccid3hctx_p > 0)
                                hctx->ccid3hctx_x_calc =
                                        tfrc_calc_x(hctx->ccid3hctx_s,
                                                    hctx->ccid3hctx_rtt,
                                                    hctx->ccid3hctx_p);
                        ccid3_hc_tx_update_x(sk, &now);

                        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, hctx->ccid3hctx_rtt, r_sample,
                                       hctx->ccid3hctx_s, hctx->ccid3hctx_p,
                                       hctx->ccid3hctx_x_calc,
                                       (unsigned)(hctx->ccid3hctx_x_recv >> 6),
                                       (unsigned)(hctx->ccid3hctx_x >> 6));
                }

                /* unschedule no feedback timer */
                sk_stop_timer(sk, &hctx->ccid3hctx_no_feedback_timer);

                /* remove all packets older than the one acked from history */
                dccp_tx_hist_purge_older(ccid3_tx_hist,
                                         &hctx->ccid3hctx_hist, packet);
                /*
                 * 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.
                 * We use a configuration option to increase the lower bound.
                 * This can help avoid triggering the nofeedback timer too
                 * often ('spinning') on LANs with small RTTs.
                 */
                hctx->ccid3hctx_t_rto = max_t(u32, 4 * hctx->ccid3hctx_rtt,
                                                   CONFIG_IP_DCCP_CCID3_RTO *
                                                   (USEC_PER_SEC/1000));
                /*
                 * Schedule no feedback timer to expire in
                 * max(t_RTO, 2 * s/X)  =  max(t_RTO, 2 * t_ipi)
                 */
                t_nfb = max(hctx->ccid3hctx_t_rto, 2 * hctx->ccid3hctx_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, &hctx->ccid3hctx_no_feedback_timer,
                                   jiffies + usecs_to_jiffies(t_nfb));

                /* set idle flag */
                hctx->ccid3hctx_idle = 1;
                break;
        case TFRC_SSTATE_NO_SENT:       /* fall through */
        case TFRC_SSTATE_TERM:          /* ignore feedback when closing */
                break;
        }
}

static int ccid3_hc_tx_parse_options(struct sock *sk, unsigned char option,
                                     unsigned char len, u16 idx,
                                     unsigned char *value)
{
        int rc = 0;
        const struct dccp_sock *dp = dccp_sk(sk);
        struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
        struct ccid3_options_received *opt_recv;
        __be32 opt_val;

        opt_recv = &hctx->ccid3hctx_options_received;

        if (opt_recv->ccid3or_seqno != dp->dccps_gsr) {
                opt_recv->ccid3or_seqno              = dp->dccps_gsr;
                opt_recv->ccid3or_loss_event_rate    = ~0;
                opt_recv->ccid3or_loss_intervals_idx = 0;
                opt_recv->ccid3or_loss_intervals_len = 0;
                opt_recv->ccid3or_receive_rate       = 0;
        }

        switch (option) {
        case TFRC_OPT_LOSS_EVENT_RATE:
                if (unlikely(len != 4)) {
                        DCCP_WARN("%s(%p), invalid len %d "
                                  "for TFRC_OPT_LOSS_EVENT_RATE\n",
                                  dccp_role(sk), sk, len);
                        rc = -EINVAL;
                } else {
                        opt_val = get_unaligned((__be32 *)value);
                        opt_recv->ccid3or_loss_event_rate = ntohl(opt_val);
                        ccid3_pr_debug("%s(%p), LOSS_EVENT_RATE=%u\n",
                                       dccp_role(sk), sk,
                                       opt_recv->ccid3or_loss_event_rate);
                }
                break;
        case TFRC_OPT_LOSS_INTERVALS:
                opt_recv->ccid3or_loss_intervals_idx = idx;
                opt_recv->ccid3or_loss_intervals_len = len;
                ccid3_pr_debug("%s(%p), LOSS_INTERVALS=(%u, %u)\n",
                               dccp_role(sk), sk,
                               opt_recv->ccid3or_loss_intervals_idx,
                               opt_recv->ccid3or_loss_intervals_len);
                break;
        case TFRC_OPT_RECEIVE_RATE:
                if (unlikely(len != 4)) {
                        DCCP_WARN("%s(%p), invalid len %d "
                                  "for TFRC_OPT_RECEIVE_RATE\n",
                                  dccp_role(sk), sk, len);
                        rc = -EINVAL;
                } else {
                        opt_val = get_unaligned((__be32 *)value);
                        opt_recv->ccid3or_receive_rate = ntohl(opt_val);
                        ccid3_pr_debug("%s(%p), RECEIVE_RATE=%u\n",
                                       dccp_role(sk), sk,
                                       opt_recv->ccid3or_receive_rate);
                }
                break;
        }

        return rc;
}

static int ccid3_hc_tx_init(struct ccid *ccid, struct sock *sk)
{
        struct ccid3_hc_tx_sock *hctx = ccid_priv(ccid);

        hctx->ccid3hctx_state = TFRC_SSTATE_NO_SENT;
        INIT_LIST_HEAD(&hctx->ccid3hctx_hist);

        hctx->ccid3hctx_no_feedback_timer.function =
                                ccid3_hc_tx_no_feedback_timer;
        hctx->ccid3hctx_no_feedback_timer.data     = (unsigned long)sk;
        init_timer(&hctx->ccid3hctx_no_feedback_timer);

        return 0;
}

static void ccid3_hc_tx_exit(struct sock *sk)
{
        struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);

        ccid3_hc_tx_set_state(sk, TFRC_SSTATE_TERM);
        sk_stop_timer(sk, &hctx->ccid3hctx_no_feedback_timer);

        /* Empty packet history */
        dccp_tx_hist_purge(ccid3_tx_hist, &hctx->ccid3hctx_hist);
}

static void ccid3_hc_tx_get_info(struct sock *sk, struct tcp_info *info)
{
        struct ccid3_hc_tx_sock *hctx;

        /* Listen socks doesn't have a private CCID block */
        if (sk->sk_state == DCCP_LISTEN)
                return;

        hctx = ccid3_hc_tx_sk(sk);
        info->tcpi_rto = hctx->ccid3hctx_t_rto;
        info->tcpi_rtt = hctx->ccid3hctx_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 *hctx;
        const void *val;

        /* Listen socks doesn't have a private CCID block */
        if (sk->sk_state == DCCP_LISTEN)
                return -EINVAL;

        hctx = ccid3_hc_tx_sk(sk);
        switch (optname) {
        case DCCP_SOCKOPT_CCID_TX_INFO:
                if (len < sizeof(hctx->ccid3hctx_tfrc))
                        return -EINVAL;
                len = sizeof(hctx->ccid3hctx_tfrc);
                val = &hctx->ccid3hctx_tfrc;
                break;
        default:
                return -ENOPROTOOPT;
        }

        if (put_user(len, optlen) || copy_to_user(optval, val, len))
                return -EFAULT;

        return 0;
}

/*
 *      Receiver Half-Connection Routines
 */
#ifdef CONFIG_IP_DCCP_CCID3_DEBUG
static const char *ccid3_rx_state_name(enum ccid3_hc_rx_states state)
{
        static char *ccid3_rx_state_names[] = {
        [TFRC_RSTATE_NO_DATA] = "NO_DATA",
        [TFRC_RSTATE_DATA]    = "DATA",
        [TFRC_RSTATE_TERM]    = "TERM",
        };

        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 *hcrx = ccid3_hc_rx_sk(sk);
        enum ccid3_hc_rx_states oldstate = hcrx->ccid3hcrx_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);
        hcrx->ccid3hcrx_state = state;
}

static inline void ccid3_hc_rx_update_s(struct ccid3_hc_rx_sock *hcrx, int len)
{
        if (unlikely(len == 0)) /* don't update on empty packets (e.g. ACKs) */
                ccid3_pr_debug("Packet payload length is 0 - not updating\n");
        else
                hcrx->ccid3hcrx_s = hcrx->ccid3hcrx_s == 0 ? len :
                                    (9 * hcrx->ccid3hcrx_s + len) / 10;
}

static void ccid3_hc_rx_send_feedback(struct sock *sk)
{
        struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);
        struct dccp_sock *dp = dccp_sk(sk);
        struct dccp_rx_hist_entry *packet;
        ktime_t now;
        suseconds_t delta;

        ccid3_pr_debug("%s(%p) - entry \n", dccp_role(sk), sk);

        now = ktime_get_real();

        switch (hcrx->ccid3hcrx_state) {
        case TFRC_RSTATE_NO_DATA:
                hcrx->ccid3hcrx_x_recv = 0;
                break;
        case TFRC_RSTATE_DATA:
                delta = ktime_us_delta(now,
                                       hcrx->ccid3hcrx_tstamp_last_feedback);
                DCCP_BUG_ON(delta < 0);
                hcrx->ccid3hcrx_x_recv =
                        scaled_div32(hcrx->ccid3hcrx_bytes_recv, delta);
                break;
        case TFRC_RSTATE_TERM:
                DCCP_BUG("%s(%p) - Illegal state TERM", dccp_role(sk), sk);
                return;
        }

        packet = dccp_rx_hist_find_data_packet(&hcrx->ccid3hcrx_hist);
        if (unlikely(packet == NULL)) {
                DCCP_WARN("%s(%p), no data packet in history!\n",
                          dccp_role(sk), sk);
                return;
        }

        hcrx->ccid3hcrx_tstamp_last_feedback = now;
        hcrx->ccid3hcrx_ccval_last_counter   = packet->dccphrx_ccval;
        hcrx->ccid3hcrx_bytes_recv           = 0;

        /* Elapsed time information [RFC 4340, 13.2] in units of 10 * usecs */
        delta = ktime_us_delta(now, packet->dccphrx_tstamp);
        DCCP_BUG_ON(delta < 0);
        hcrx->ccid3hcrx_elapsed_time = delta / 10;

        if (hcrx->ccid3hcrx_p == 0)
                hcrx->ccid3hcrx_pinv = ~0U;     /* see RFC 4342, 8.5 */
        else if (hcrx->ccid3hcrx_p > 1000000) {
                DCCP_WARN("p (%u) > 100%%\n", hcrx->ccid3hcrx_p);
                hcrx->ccid3hcrx_pinv = 1;       /* use 100% in this case */
        } else
                hcrx->ccid3hcrx_pinv = 1000000 / hcrx->ccid3hcrx_p;

        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 *hcrx;
        __be32 x_recv, pinv;

        if (!(sk->sk_state == DCCP_OPEN || sk->sk_state == DCCP_PARTOPEN))
                return 0;

        hcrx = ccid3_hc_rx_sk(sk);
        DCCP_SKB_CB(skb)->dccpd_ccval = hcrx->ccid3hcrx_ccval_last_counter;

        if (dccp_packet_without_ack(skb))
                return 0;

        x_recv = htonl(hcrx->ccid3hcrx_x_recv);
        pinv   = htonl(hcrx->ccid3hcrx_pinv);

        if ((hcrx->ccid3hcrx_elapsed_time != 0 &&
             dccp_insert_option_elapsed_time(sk, skb,
                                             hcrx->ccid3hcrx_elapsed_time)) ||
            dccp_insert_option_timestamp(sk, skb) ||
            dccp_insert_option(sk, skb, TFRC_OPT_LOSS_EVENT_RATE,
                               &pinv, sizeof(pinv)) ||
            dccp_insert_option(sk, skb, TFRC_OPT_RECEIVE_RATE,
                               &x_recv, sizeof(x_recv)))
                return -1;

        return 0;
}

static int ccid3_hc_rx_detect_loss(struct sock *sk,
                                    struct dccp_rx_hist_entry *packet)
{
        struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);
        struct dccp_rx_hist_entry *rx_hist =
                                dccp_rx_hist_head(&hcrx->ccid3hcrx_hist);
        u64 seqno = packet->dccphrx_seqno;
        u64 tmp_seqno;
        int loss = 0;
        u8 ccval;


        tmp_seqno = hcrx->ccid3hcrx_seqno_nonloss;

        if (!rx_hist ||
           follows48(packet->dccphrx_seqno, hcrx->ccid3hcrx_seqno_nonloss)) {
                hcrx->ccid3hcrx_seqno_nonloss = seqno;
                hcrx->ccid3hcrx_ccval_nonloss = packet->dccphrx_ccval;
                goto detect_out;
        }


        while (dccp_delta_seqno(hcrx->ccid3hcrx_seqno_nonloss, seqno)
           > TFRC_RECV_NUM_LATE_LOSS) {
                loss = 1;
                dccp_li_update_li(sk,
                                  &hcrx->ccid3hcrx_li_hist,
                                  &hcrx->ccid3hcrx_hist,
                                  hcrx->ccid3hcrx_tstamp_last_feedback,
                                  hcrx->ccid3hcrx_s,
                                  hcrx->ccid3hcrx_bytes_recv,
                                  hcrx->ccid3hcrx_x_recv,
                                  hcrx->ccid3hcrx_seqno_nonloss,
                                  hcrx->ccid3hcrx_ccval_nonloss);
                tmp_seqno = hcrx->ccid3hcrx_seqno_nonloss;
                dccp_inc_seqno(&tmp_seqno);
                hcrx->ccid3hcrx_seqno_nonloss = tmp_seqno;
                dccp_inc_seqno(&tmp_seqno);
                while (dccp_rx_hist_find_entry(&hcrx->ccid3hcrx_hist,
                   tmp_seqno, &ccval)) {
                        hcrx->ccid3hcrx_seqno_nonloss = tmp_seqno;
                        hcrx->ccid3hcrx_ccval_nonloss = ccval;
                        dccp_inc_seqno(&tmp_seqno);
                }
        }

        /* FIXME - this code could be simplified with above while */
        /* but works at moment */
        if (follows48(packet->dccphrx_seqno, hcrx->ccid3hcrx_seqno_nonloss)) {
                hcrx->ccid3hcrx_seqno_nonloss = seqno;
                hcrx->ccid3hcrx_ccval_nonloss = packet->dccphrx_ccval;
        }

detect_out:
        dccp_rx_hist_add_packet(ccid3_rx_hist, &hcrx->ccid3hcrx_hist,
                   &hcrx->ccid3hcrx_li_hist, packet,
                   hcrx->ccid3hcrx_seqno_nonloss);
        return loss;
}

static void ccid3_hc_rx_packet_recv(struct sock *sk, struct sk_buff *skb)
{
        struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);
        const struct dccp_options_received *opt_recv;
        struct dccp_rx_hist_entry *packet;
        u32 p_prev, r_sample, rtt_prev;
        int loss, payload_size;
        ktime_t now;

        opt_recv = &dccp_sk(sk)->dccps_options_received;

        switch (DCCP_SKB_CB(skb)->dccpd_type) {
        case DCCP_PKT_ACK:
                if (hcrx->ccid3hcrx_state == TFRC_RSTATE_NO_DATA)
                        return;
        case DCCP_PKT_DATAACK:
                if (opt_recv->dccpor_timestamp_echo == 0)
                        break;
                r_sample = dccp_timestamp() - opt_recv->dccpor_timestamp_echo;
                rtt_prev = hcrx->ccid3hcrx_rtt;
                r_sample = dccp_sample_rtt(sk, 10 * r_sample);

                if (hcrx->ccid3hcrx_state == TFRC_RSTATE_NO_DATA)
                        hcrx->ccid3hcrx_rtt = r_sample;
                else
                        hcrx->ccid3hcrx_rtt = (hcrx->ccid3hcrx_rtt * 9) / 10 +
                                              r_sample / 10;

                if (rtt_prev != hcrx->ccid3hcrx_rtt)
                        ccid3_pr_debug("%s(%p), New RTT=%uus, elapsed time=%u\n",
                                       dccp_role(sk), sk, hcrx->ccid3hcrx_rtt,
                                       opt_recv->dccpor_elapsed_time);
                break;
        case DCCP_PKT_DATA:
                break;
        default: /* We're not interested in other packet types, move along */
                return;
        }

        packet = dccp_rx_hist_entry_new(ccid3_rx_hist, opt_recv->dccpor_ndp,
                                        skb, GFP_ATOMIC);
        if (unlikely(packet == NULL)) {
                DCCP_WARN("%s(%p), Not enough mem to add rx packet "
                          "to history, consider it lost!\n", dccp_role(sk), sk);
                return;
        }

        loss = ccid3_hc_rx_detect_loss(sk, packet);

        if (DCCP_SKB_CB(skb)->dccpd_type == DCCP_PKT_ACK)
                return;

        payload_size = skb->len - dccp_hdr(skb)->dccph_doff * 4;
        ccid3_hc_rx_update_s(hcrx, payload_size);

        switch (hcrx->ccid3hcrx_state) {
        case TFRC_RSTATE_NO_DATA:
                ccid3_pr_debug("%s(%p, state=%s), skb=%p, sending initial "
                               "feedback\n", dccp_role(sk), sk,
                               dccp_state_name(sk->sk_state), skb);
                ccid3_hc_rx_send_feedback(sk);
                ccid3_hc_rx_set_state(sk, TFRC_RSTATE_DATA);
                return;
        case TFRC_RSTATE_DATA:
                hcrx->ccid3hcrx_bytes_recv += payload_size;
                if (loss)
                        break;

                now = ktime_get_real();
                if ((ktime_us_delta(now, hcrx->ccid3hcrx_tstamp_last_ack) -
                     (s64)hcrx->ccid3hcrx_rtt) >= 0) {
                        hcrx->ccid3hcrx_tstamp_last_ack = now;
                        ccid3_hc_rx_send_feedback(sk);
                }
                return;
        case TFRC_RSTATE_TERM:
                DCCP_BUG("%s(%p) - Illegal state TERM", dccp_role(sk), sk);
                return;
        }

        /* Dealing with packet loss */
        ccid3_pr_debug("%s(%p, state=%s), data loss! Reacting...\n",
                       dccp_role(sk), sk, dccp_state_name(sk->sk_state));

        p_prev = hcrx->ccid3hcrx_p;

        /* Calculate loss event rate */
        if (!list_empty(&hcrx->ccid3hcrx_li_hist)) {
                u32 i_mean = dccp_li_hist_calc_i_mean(&hcrx->ccid3hcrx_li_hist);

                /* Scaling up by 1000000 as fixed decimal */
                if (i_mean != 0)
                        hcrx->ccid3hcrx_p = 1000000 / i_mean;
        } else
                DCCP_BUG("empty loss history");

        if (hcrx->ccid3hcrx_p > p_prev) {
                ccid3_hc_rx_send_feedback(sk);
                return;
        }
}

static int ccid3_hc_rx_init(struct ccid *ccid, struct sock *sk)
{
        struct ccid3_hc_rx_sock *hcrx = ccid_priv(ccid);

        ccid3_pr_debug("entry\n");

        hcrx->ccid3hcrx_state = TFRC_RSTATE_NO_DATA;
        INIT_LIST_HEAD(&hcrx->ccid3hcrx_hist);
        INIT_LIST_HEAD(&hcrx->ccid3hcrx_li_hist);
        hcrx->ccid3hcrx_tstamp_last_feedback =
                hcrx->ccid3hcrx_tstamp_last_ack = ktime_get_real();
        return 0;
}

static void ccid3_hc_rx_exit(struct sock *sk)
{
        struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);

        ccid3_hc_rx_set_state(sk, TFRC_RSTATE_TERM);

        /* Empty packet history */
        dccp_rx_hist_purge(ccid3_rx_hist, &hcrx->ccid3hcrx_hist);

        /* Empty loss interval history */
        dccp_li_hist_purge(&hcrx->ccid3hcrx_li_hist);
}

static void ccid3_hc_rx_get_info(struct sock *sk, struct tcp_info *info)
{
        const struct ccid3_hc_rx_sock *hcrx;

        /* Listen socks doesn't have a private CCID block */
        if (sk->sk_state == DCCP_LISTEN)
                return;

        hcrx = ccid3_hc_rx_sk(sk);
        info->tcpi_ca_state = hcrx->ccid3hcrx_state;
        info->tcpi_options  |= TCPI_OPT_TIMESTAMPS;
        info->tcpi_rcv_rtt  = hcrx->ccid3hcrx_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 *hcrx;
        const void *val;

        /* Listen socks doesn't have a private CCID block */
        if (sk->sk_state == DCCP_LISTEN)
                return -EINVAL;

        hcrx = ccid3_hc_rx_sk(sk);
        switch (optname) {
        case DCCP_SOCKOPT_CCID_RX_INFO:
                if (len < sizeof(hcrx->ccid3hcrx_tfrc))
                        return -EINVAL;
                len = sizeof(hcrx->ccid3hcrx_tfrc);
                val = &hcrx->ccid3hcrx_tfrc;
                break;
        default:
                return -ENOPROTOOPT;
        }

        if (put_user(len, optlen) || copy_to_user(optval, val, len))
                return -EFAULT;

        return 0;
}

static struct ccid_operations ccid3 = {
        .ccid_id                   = DCCPC_CCID3,
        .ccid_name                 = "ccid3",
        .ccid_owner                = THIS_MODULE,
        .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, 0444);
MODULE_PARM_DESC(ccid3_debug, "Enable debug messages");
#endif

static __init int ccid3_module_init(void)
{
        int rc = -ENOBUFS;

        ccid3_rx_hist = dccp_rx_hist_new("ccid3");
        if (ccid3_rx_hist == NULL)
                goto out;

        ccid3_tx_hist = dccp_tx_hist_new("ccid3");
        if (ccid3_tx_hist == NULL)
                goto out_free_rx;

        rc = ccid_register(&ccid3);
        if (rc != 0)
                goto out_free_tx;
out:
        return rc;

out_free_tx:
        dccp_tx_hist_delete(ccid3_tx_hist);
        ccid3_tx_hist = NULL;
out_free_rx:
        dccp_rx_hist_delete(ccid3_rx_hist);
        ccid3_rx_hist = NULL;
        goto out;
}
module_init(ccid3_module_init);

static __exit void ccid3_module_exit(void)
{
        ccid_unregister(&ccid3);

        if (ccid3_tx_hist != NULL) {
                dccp_tx_hist_delete(ccid3_tx_hist);
                ccid3_tx_hist = NULL;
        }
        if (ccid3_rx_hist != NULL) {
                dccp_rx_hist_delete(ccid3_rx_hist);
                ccid3_rx_hist = NULL;
        }
}
module_exit(ccid3_module_exit);

MODULE_AUTHOR("Ian McDonald <ian.mcdonald@jandi.co.nz>, "
              "Arnaldo Carvalho de Melo <acme@ghostprotocols.net>");
MODULE_DESCRIPTION("DCCP TFRC CCID3 CCID");
MODULE_LICENSE("GPL");
MODULE_ALIAS("net-dccp-ccid-3");