[DCCP] ccid3: Finer-grained resolution of sending rates

[linux-2.6.22.y-op.git] / net / dccp / ccids / ccid3.c

/*
 *  net/dccp/ccids/ccid3.c
 *
 *  Copyright (c) 2005 The University of Waikato, Hamilton, New Zealand.
 *  Copyright (c) 2005-6 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"

/*
 * Reason for maths here is to avoid 32 bit overflow when a is big.
 * With this we get close to the limit.
 */
static u32 usecs_div(const u32 a, const u32 b)
{
        const u32 div = a < (UINT_MAX / (USEC_PER_SEC /    10)) ?    10 :
                        a < (UINT_MAX / (USEC_PER_SEC /    50)) ?    50 :
                        a < (UINT_MAX / (USEC_PER_SEC /   100)) ?   100 :
                        a < (UINT_MAX / (USEC_PER_SEC /   500)) ?   500 :
                        a < (UINT_MAX / (USEC_PER_SEC /  1000)) ?  1000 :
                        a < (UINT_MAX / (USEC_PER_SEC /  5000)) ?  5000 :
                        a < (UINT_MAX / (USEC_PER_SEC / 10000)) ? 10000 :
                        a < (UINT_MAX / (USEC_PER_SEC / 50000)) ? 50000 :
                                                                 100000;
        const u32 tmp = a * (USEC_PER_SEC / div);
        return (b >= 2 * div) ? tmp / (b / div) : tmp;
}



#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;
static struct dccp_li_hist *ccid3_li_hist;

#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;
}

/*
 * Recalculate scheduled nominal send time t_nom, inter-packet interval
 * t_ipi, and delta value. Should be called after each change to X.
 */
static inline void ccid3_update_send_time(struct ccid3_hc_tx_sock *hctx)
{
        timeval_sub_usecs(&hctx->ccid3hctx_t_nom, hctx->ccid3hctx_t_ipi);

        /* Calculate new t_ipi = s / X_inst (X_inst is in 64 * bytes/second) */
        hctx->ccid3hctx_t_ipi = scaled_div(hctx->ccid3hctx_s,
                                           hctx->ccid3hctx_x >> 6);

        /* Update nominal send time with regard to the new t_ipi */
        timeval_add_usecs(&hctx->ccid3hctx_t_nom, hctx->ccid3hctx_t_ipi);

        /* 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);
}
/*
 * Update X by
 *    If (p > 0)
 *       X_calc = calcX(s, R, p);
 *       X = max(min(X_calc, 2 * X_recv), s / t_mbi);
 *    Else
 *       If (now - tld >= R)
 *          X = max(min(2 * X, 2 * X_recv), s / R);
 *          tld = now;
 *
 * 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).
 *
 * If X has changed, we also update the scheduled send time t_now,
 * the inter-packet interval t_ipi, and the delta value.
 */
static void ccid3_hc_tx_update_x(struct sock *sk, struct timeval *now)

{
        struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
        const  __u64 old_x = hctx->ccid3hctx_x;

        if (hctx->ccid3hctx_p > 0) {

                hctx->ccid3hctx_x = min_t(u64, hctx->ccid3hctx_x_calc << 6,
                                               hctx->ccid3hctx_x_recv * 2  );
                hctx->ccid3hctx_x = max_t(u64, hctx->ccid3hctx_x,
                                          (hctx->ccid3hctx_s << 6)/TFRC_T_MBI);

        } else if (timeval_delta(now, &hctx->ccid3hctx_t_ld) >=
                                                          hctx->ccid3hctx_rtt) {

                hctx->ccid3hctx_x = max(2 * min(hctx->ccid3hctx_x,
                                                hctx->ccid3hctx_x_recv),
                                        scaled_div(hctx->ccid3hctx_s << 6,
                                                   hctx->ccid3hctx_rtt    ));
                hctx->ccid3hctx_t_ld = *now;
        }

        if (hctx->ccid3hctx_x != old_x)
                ccid3_update_send_time(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)
{
        if (unlikely(len == 0))
                ccid3_pr_debug("Packet payload length is 0 - not updating\n");
        else
                hctx->ccid3hctx_s = hctx->ccid3hctx_s == 0 ? len :
                                    (9 * hctx->ccid3hctx_s + len) / 10;
        /*
         * Note: We could do a potential optimisation here - when `s' changes,
         *       recalculate sending rate and consequently t_ipi, t_delta, and
         *       t_now. This is however non-standard, and the benefits are not
         *       clear, so it is currently left out.
         */
}

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, sk=%p, state=%s\n", dccp_role(sk), sk,
                       ccid3_tx_state_name(hctx->ccid3hctx_state));
        
        switch (hctx->ccid3hctx_state) {
        case TFRC_SSTATE_NO_FBACK:
                /* RFC 3448, 4.4: Halve send rate directly */
                hctx->ccid3hctx_x = max_t(u32, hctx->ccid3hctx_x / 2,
                                          (hctx->ccid3hctx_s << 6)/TFRC_T_MBI);

                ccid3_pr_debug("%s, sk=%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 timout value. Keep initial value as per [RFC 4342, 5]. */
                t_nfb = TFRC_INITIAL_TIMEOUT;
                ccid3_update_send_time(hctx);
                break;
        case TFRC_SSTATE_FBACK:
                /*
                 * Check if IDLE since last timeout and recv rate is less than
                 * 4 packets (in units of 64*bytes/sec) per RTT
                 */
                if (!hctx->ccid3hctx_idle ||
                    (hctx->ccid3hctx_x_recv >= 4 *
                     scaled_div(hctx->ccid3hctx_s << 6, hctx->ccid3hctx_rtt))) {
                        struct timeval now;

                        ccid3_pr_debug("%s, sk=%p, state=%s, not idle\n",
                                       dccp_role(sk), sk,
                                       ccid3_tx_state_name(hctx->ccid3hctx_state));

                        /*
                         *  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_t(u64, hctx->ccid3hctx_x_recv / 2,
                                                  (hctx->ccid3hctx_s << 6) /
                                                                (2*TFRC_T_MBI));

                                if (hctx->ccid3hctx_p == 0)
                                        dccp_timestamp(sk, &now);
                        } else
                                hctx->ccid3hctx_x_recv = hctx->ccid3hctx_x_calc << 4;

                        /* Now recalculate X [RFC 3448, 4.3, step (4)] */
                        ccid3_hc_tx_update_x(sk, &now);
                }
                /*
                 * 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("Illegal %s state NO_SENT, sk=%p", dccp_role(sk), sk);
                /* fall through */
        case TFRC_SSTATE_TERM:
                goto out;
        }

        hctx->ccid3hctx_idle = 1;

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);
        struct dccp_tx_hist_entry *new_packet;
        struct timeval now;
        long delay;

        BUG_ON(hctx == NULL);

        /*
         * 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;

        /* See if last packet allocated was not sent */
        new_packet = dccp_tx_hist_head(&hctx->ccid3hctx_hist);
        if (new_packet == NULL || new_packet->dccphtx_sent) {
                new_packet = dccp_tx_hist_entry_new(ccid3_tx_hist,
                                                    GFP_ATOMIC);

                if (unlikely(new_packet == NULL)) {
                        DCCP_WARN("%s, sk=%p, not enough mem to add to history,"
                                  "send refused\n", dccp_role(sk), sk);
                        return -ENOBUFS;
                }

                dccp_tx_hist_add_entry(&hctx->ccid3hctx_hist, new_packet);
        }

        dccp_timestamp(sk, &now);

        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;
                ccid3_hc_tx_set_state(sk, TFRC_SSTATE_NO_FBACK);

                /* Set initial sending rate X/s to 1pps (X is scaled by 2^6) */
                ccid3_hc_tx_update_s(hctx, skb->len);
                hctx->ccid3hctx_x = hctx->ccid3hctx_s << 6;

                /* First timeout, according to [RFC 3448, 4.2], is 1 second */
                hctx->ccid3hctx_t_ipi = USEC_PER_SEC;
                /* Initial delta: minimum of 0.5 sec and t_gran/2 */
                hctx->ccid3hctx_delta = TFRC_OPSYS_HALF_TIME_GRAN;

                /* Set t_0 for initial packet */
                hctx->ccid3hctx_t_nom = now;
                break;
        case TFRC_SSTATE_NO_FBACK:
        case TFRC_SSTATE_FBACK:
                delay = timeval_delta(&hctx->ccid3hctx_t_nom, &now);
                /*
                 *      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 - (long)hctx->ccid3hctx_delta >= 0)
                        return delay / 1000L;
                break;
        case TFRC_SSTATE_TERM:
                DCCP_BUG("Illegal %s state TERM, sk=%p", dccp_role(sk), sk);
                return -EINVAL;
        }

        /* prepare to send now (add options etc.) */
        dp->dccps_hc_tx_insert_options = 1;
        new_packet->dccphtx_ccval = DCCP_SKB_CB(skb)->dccpd_ccval =
                                    hctx->ccid3hctx_last_win_count;
        timeval_add_usecs(&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)
{
        const struct dccp_sock *dp = dccp_sk(sk);
        struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
        struct timeval now;
        unsigned long quarter_rtt;
        struct dccp_tx_hist_entry *packet;

        BUG_ON(hctx == NULL);

        dccp_timestamp(sk, &now);

        ccid3_hc_tx_update_s(hctx, len);

        packet = dccp_tx_hist_head(&hctx->ccid3hctx_hist);
        if (unlikely(packet == NULL)) {
                DCCP_WARN("packet doesn't exist in history!\n");
                return;
        }
        if (unlikely(packet->dccphtx_sent)) {
                DCCP_WARN("no unsent packet in history!\n");
                return;
        }
        packet->dccphtx_tstamp = now;
        packet->dccphtx_seqno  = dp->dccps_gss;
        /*
         * Check if win_count have changed
         * Algorithm in "8.1. Window Counter Value" in RFC 4342.
         */
        quarter_rtt = timeval_delta(&now, &hctx->ccid3hctx_t_last_win_count);
        if (likely(hctx->ccid3hctx_rtt > 8))
                quarter_rtt /= hctx->ccid3hctx_rtt / 4;

        if (quarter_rtt > 0) {
                hctx->ccid3hctx_t_last_win_count = now;
                hctx->ccid3hctx_last_win_count   = (hctx->ccid3hctx_last_win_count +
                                                    min_t(unsigned long, quarter_rtt, 5)) % 16;
                ccid3_pr_debug("%s, sk=%p, window changed from "
                               "%u to %u!\n",
                               dccp_role(sk), sk,
                               packet->dccphtx_ccval,
                               hctx->ccid3hctx_last_win_count);
        }

        hctx->ccid3hctx_idle = 0;
        packet->dccphtx_rtt  = hctx->ccid3hctx_rtt;
        packet->dccphtx_sent = 1;
}

static void ccid3_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
{
        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;
        struct dccp_tx_hist_entry *packet;
        struct timeval now;
        unsigned long t_nfb;
        u32 pinv;
        long r_sample, t_elapsed;

        BUG_ON(hctx == NULL);

        /* 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 << 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;

                dccp_timestamp(sk, &now);

                /*
                 * Calculate new round trip sample as per [RFC 3448, 4.3] by
                 *      R_sample  =  (now - t_recvdata) - t_elapsed
                 */
                r_sample  = timeval_delta(&now, &packet->dccphtx_tstamp);
                t_elapsed = dp->dccps_options_received.dccpor_elapsed_time * 10;

                if (unlikely(r_sample <= 0)) {
                        DCCP_WARN("WARNING: R_sample (%ld) <= 0!\n", r_sample);
                        r_sample = 0;
                } else if (unlikely(r_sample <= t_elapsed))
                        DCCP_WARN("WARNING: r_sample=%ldus <= t_elapsed=%ldus\n",
                                  r_sample, t_elapsed);
                else
                        r_sample -= t_elapsed;

                /* 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]
                         * We deviate in that we use `s' instead of `MSS'.
                         */
                        u16 w_init = min(    4 * hctx->ccid3hctx_s,
                                         max(2 * hctx->ccid3hctx_s, 4380));
                        hctx->ccid3hctx_rtt  = r_sample;
                        hctx->ccid3hctx_x    = scaled_div(w_init<< 6, r_sample);
                        hctx->ccid3hctx_t_ld = now;

                        ccid3_update_send_time(hctx);

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

                        ccid3_hc_tx_set_state(sk, TFRC_SSTATE_FBACK);
                } else {
                        hctx->ccid3hctx_rtt = (9 * hctx->ccid3hctx_rtt +
                                                   (u32)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=%ldus), s=%u, "
                                       "p=%u, X_calc=%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 >> 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, sk=%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:
                if (dccp_sk(sk)->dccps_role == DCCP_ROLE_CLIENT)
                        DCCP_WARN("Illegal ACK received - no packet sent\n");
                /* fall through */
        case TFRC_SSTATE_TERM:          /* ignore feedback when closing */
                break;
        }
}

static int ccid3_hc_tx_insert_options(struct sock *sk, struct sk_buff *skb)
{
        const struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);

        BUG_ON(hctx == NULL);

        if (sk->sk_state == DCCP_OPEN || sk->sk_state == DCCP_PARTOPEN)
                DCCP_SKB_CB(skb)->dccpd_ccval = hctx->ccid3hctx_last_win_count;
        return 0;
}

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;

        BUG_ON(hctx == NULL);

        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, sk=%p, invalid len %d "
                                  "for TFRC_OPT_LOSS_EVENT_RATE\n",
                                  dccp_role(sk), sk, len);
                        rc = -EINVAL;
                } else {
                        opt_recv->ccid3or_loss_event_rate = ntohl(*(__be32 *)value);
                        ccid3_pr_debug("%s, sk=%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, sk=%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, sk=%p, invalid len %d "
                                  "for TFRC_OPT_RECEIVE_RATE\n",
                                  dccp_role(sk), sk, len);
                        rc = -EINVAL;
                } else {
                        opt_recv->ccid3or_receive_rate = ntohl(*(__be32 *)value);
                        ccid3_pr_debug("%s, sk=%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_s     = 0;
        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);

        BUG_ON(hctx == NULL);

        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);
}

/*
 * RX Half Connection methods
 */

#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;
        struct timeval now;

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

        dccp_timestamp(sk, &now);

        switch (hcrx->ccid3hcrx_state) {
        case TFRC_RSTATE_NO_DATA:
                hcrx->ccid3hcrx_x_recv = 0;
                break;
        case TFRC_RSTATE_DATA: {
                const u32 delta = timeval_delta(&now,
                                        &hcrx->ccid3hcrx_tstamp_last_feedback);
                hcrx->ccid3hcrx_x_recv = usecs_div(hcrx->ccid3hcrx_bytes_recv,
                                                   delta);
        }
                break;
        case TFRC_RSTATE_TERM:
                DCCP_BUG("Illegal %s state TERM, sk=%p", dccp_role(sk), sk);
                return;
        }

        packet = dccp_rx_hist_find_data_packet(&hcrx->ccid3hcrx_hist);
        if (unlikely(packet == NULL)) {
                DCCP_WARN("%s, sk=%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;

        /* Convert to multiples of 10us */
        hcrx->ccid3hcrx_elapsed_time =
                        timeval_delta(&now, &packet->dccphrx_tstamp) / 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 = ccid3_hc_rx_sk(sk);
        __be32 x_recv, pinv;

        BUG_ON(hcrx == NULL);

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

        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;
}

/* calculate first loss interval
 *
 * returns estimated loss interval in usecs */

static u32 ccid3_hc_rx_calc_first_li(struct sock *sk)
{
        struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);
        struct dccp_rx_hist_entry *entry, *next, *tail = NULL;
        u32 rtt, delta, x_recv, fval, p, tmp2;
        struct timeval tstamp = { 0, };
        int interval = 0;
        int win_count = 0;
        int step = 0;
        u64 tmp1;

        list_for_each_entry_safe(entry, next, &hcrx->ccid3hcrx_hist,
                                 dccphrx_node) {
                if (dccp_rx_hist_entry_data_packet(entry)) {
                        tail = entry;

                        switch (step) {
                        case 0:
                                tstamp    = entry->dccphrx_tstamp;
                                win_count = entry->dccphrx_ccval;
                                step = 1;
                                break;
                        case 1:
                                interval = win_count - entry->dccphrx_ccval;
                                if (interval < 0)
                                        interval += TFRC_WIN_COUNT_LIMIT;
                                if (interval > 4)
                                        goto found;
                                break;
                        }
                }
        }

        if (unlikely(step == 0)) {
                DCCP_WARN("%s, sk=%p, packet history has no data packets!\n",
                          dccp_role(sk), sk);
                return ~0;
        }

        if (unlikely(interval == 0)) {
                DCCP_WARN("%s, sk=%p, Could not find a win_count interval > 0."
                          "Defaulting to 1\n", dccp_role(sk), sk);
                interval = 1;
        }
found:
        if (!tail) {
                DCCP_CRIT("tail is null\n");
                return ~0;
        }
        rtt = timeval_delta(&tstamp, &tail->dccphrx_tstamp) * 4 / interval;
        ccid3_pr_debug("%s, sk=%p, approximated RTT to %uus\n",
                       dccp_role(sk), sk, rtt);

        if (rtt == 0) {
                DCCP_WARN("RTT==0, setting to 1\n");
                rtt = 1;
        }

        dccp_timestamp(sk, &tstamp);
        delta = timeval_delta(&tstamp, &hcrx->ccid3hcrx_tstamp_last_feedback);
        x_recv = usecs_div(hcrx->ccid3hcrx_bytes_recv, delta);

        if (x_recv == 0)
                x_recv = hcrx->ccid3hcrx_x_recv;

        tmp1 = (u64)x_recv * (u64)rtt;
        do_div(tmp1,10000000);
        tmp2 = (u32)tmp1;

        if (!tmp2) {
                DCCP_CRIT("tmp2 = 0, x_recv = %u, rtt =%u\n", x_recv, rtt);
                return ~0;
        }

        fval = (hcrx->ccid3hcrx_s * 100000) / tmp2;
        /* do not alter order above or you will get overflow on 32 bit */
        p = tfrc_calc_x_reverse_lookup(fval);
        ccid3_pr_debug("%s, sk=%p, receive rate=%u bytes/s, implied "
                       "loss rate=%u\n", dccp_role(sk), sk, x_recv, p);

        if (p == 0)
                return ~0;
        else
                return 1000000 / p; 
}

static void ccid3_hc_rx_update_li(struct sock *sk, u64 seq_loss, u8 win_loss)
{
        struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);
        struct dccp_li_hist_entry *head;
        u64 seq_temp;

        if (list_empty(&hcrx->ccid3hcrx_li_hist)) {
                if (!dccp_li_hist_interval_new(ccid3_li_hist,
                   &hcrx->ccid3hcrx_li_hist, seq_loss, win_loss))
                        return;

                head = list_entry(hcrx->ccid3hcrx_li_hist.next,
                   struct dccp_li_hist_entry, dccplih_node);
                head->dccplih_interval = ccid3_hc_rx_calc_first_li(sk);
        } else {
                struct dccp_li_hist_entry *entry;
                struct list_head *tail;

                head = list_entry(hcrx->ccid3hcrx_li_hist.next,
                   struct dccp_li_hist_entry, dccplih_node);
                /* FIXME win count check removed as was wrong */
                /* should make this check with receive history */
                /* and compare there as per section 10.2 of RFC4342 */

                /* new loss event detected */
                /* calculate last interval length */
                seq_temp = dccp_delta_seqno(head->dccplih_seqno, seq_loss);
                entry = dccp_li_hist_entry_new(ccid3_li_hist, GFP_ATOMIC);

                if (entry == NULL) {
                        DCCP_BUG("out of memory - can not allocate entry");
                        return;
                }

                list_add(&entry->dccplih_node, &hcrx->ccid3hcrx_li_hist);

                tail = hcrx->ccid3hcrx_li_hist.prev;
                list_del(tail);
                kmem_cache_free(ccid3_li_hist->dccplih_slab, tail);

                /* Create the newest interval */
                entry->dccplih_seqno = seq_loss;
                entry->dccplih_interval = seq_temp;
                entry->dccplih_win_count = win_loss;
        }
}

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;
                ccid3_hc_rx_update_li(sk, 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;
        struct timeval now;
        u32 p_prev, rtt_prev, r_sample, t_elapsed;
        int loss, payload_size;

        BUG_ON(hcrx == NULL);

        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;
                rtt_prev = hcrx->ccid3hcrx_rtt;
                dccp_timestamp(sk, &now);
                timeval_sub_usecs(&now, opt_recv->dccpor_timestamp_echo * 10);
                r_sample = timeval_usecs(&now);
                t_elapsed = opt_recv->dccpor_elapsed_time * 10;

                if (unlikely(r_sample <= t_elapsed))
                        DCCP_WARN("r_sample=%uus, t_elapsed=%uus\n",
                                  r_sample, t_elapsed);
                else
                        r_sample -= t_elapsed;

                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, New RTT=%uus, elapsed time=%u\n",
                                       dccp_role(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, sk, opt_recv->dccpor_ndp,
                                        skb, GFP_ATOMIC);
        if (unlikely(packet == NULL)) {
                DCCP_WARN("%s, sk=%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, sk=%p(%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;

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

        /* Dealing with packet loss */
        ccid3_pr_debug("%s, sk=%p(%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("%s, sk=%p\n", dccp_role(sk), sk);

        hcrx->ccid3hcrx_state = TFRC_RSTATE_NO_DATA;
        INIT_LIST_HEAD(&hcrx->ccid3hcrx_hist);
        INIT_LIST_HEAD(&hcrx->ccid3hcrx_li_hist);
        dccp_timestamp(sk, &hcrx->ccid3hcrx_tstamp_last_ack);
        hcrx->ccid3hcrx_tstamp_last_feedback = hcrx->ccid3hcrx_tstamp_last_ack;
        hcrx->ccid3hcrx_s   = 0;
        hcrx->ccid3hcrx_rtt = 5000; /* XXX 5ms for now... */
        return 0;
}

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

        BUG_ON(hcrx == NULL);

        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(ccid3_li_hist, &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 = ccid3_hc_rx_sk(sk);

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

        BUG_ON(hcrx == NULL);

        info->tcpi_ca_state     = hcrx->ccid3hcrx_state;
        info->tcpi_options      |= TCPI_OPT_TIMESTAMPS;
        info->tcpi_rcv_rtt      = hcrx->ccid3hcrx_rtt;
}

static void ccid3_hc_tx_get_info(struct sock *sk, struct tcp_info *info)
{
        const struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);

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

        BUG_ON(hctx == NULL);

        info->tcpi_rto = hctx->ccid3hctx_t_rto;
        info->tcpi_rtt = hctx->ccid3hctx_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 = ccid3_hc_rx_sk(sk);
        const void *val;
        
        /* Listen socks doesn't have a private CCID block */
        if (sk->sk_state == DCCP_LISTEN)
                return -EINVAL;

        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 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 = ccid3_hc_tx_sk(sk);
        const void *val;
        
        /* Listen socks doesn't have a private CCID block */
        if (sk->sk_state == DCCP_LISTEN)
                return -EINVAL;

        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;
}

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_insert_options = ccid3_hc_tx_insert_options,
        .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, int, 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;

        ccid3_li_hist = dccp_li_hist_new("ccid3");
        if (ccid3_li_hist == NULL)
                goto out_free_tx;

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

out_free_loss_interval_history:
        dccp_li_hist_delete(ccid3_li_hist);
        ccid3_li_hist = NULL;
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;
        }
        if (ccid3_li_hist != NULL) {
                dccp_li_hist_delete(ccid3_li_hist);
                ccid3_li_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");