text: /*
   *  net/dccp/ccids/ccid3.c
   *
   *  Copyright (c) 2005 The University of Waikato, Hamilton, New Zealand.
   *  Copyright (c) 2005-6 Ian McDonald <imcdnzl@gmail.com>
   *
   *  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 <linux/config.h>
  #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 inline 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;
  }
  
  static int ccid3_debug;
  
  #ifdef CCID3_DEBUG
  #define ccid3_pr_debug(format, a...) \
  	do { if (ccid3_debug) \
  		printk(KERN_DEBUG "%s: " format, __FUNCTION__, ##a); \
  	} while (0)
  #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;
  
  static int ccid3_init(struct sock *sk)
  {
  	return 0;
  }
  
  static void ccid3_exit(struct sock *sk)
  {
  }
  
  /* TFRC sender states */
  enum ccid3_hc_tx_states {
         	TFRC_SSTATE_NO_SENT = 1,
  	TFRC_SSTATE_NO_FBACK,
  	TFRC_SSTATE_FBACK,
  	TFRC_SSTATE_TERM,
  };
  
  #ifdef 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 inline 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;
  }
  
  /* Calculate new t_ipi (inter packet interval) by t_ipi = s / X_inst */
  static inline void ccid3_calc_new_t_ipi(struct ccid3_hc_tx_sock *hctx)
  {
  	/*
  	 * If no feedback spec says t_ipi is 1 second (set elsewhere and then
  	 * doubles after every no feedback timer (separate function)
  	 */
  	if (hctx->ccid3hctx_state != TFRC_SSTATE_NO_FBACK)
  		hctx->ccid3hctx_t_ipi = usecs_div(hctx->ccid3hctx_s,
  						  hctx->ccid3hctx_x);
  }
  
  /* Calculate new delta by delta = min(t_ipi / 2, t_gran / 2) */
  static inline void ccid3_calc_new_delta(struct ccid3_hc_tx_sock *hctx)
  {
  	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;
   */ 
  static void ccid3_hc_tx_update_x(struct sock *sk)
  {
  	struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
  
  	/* To avoid large error in calcX */
  	if (hctx->ccid3hctx_p >= TFRC_SMALLEST_P) {
  		hctx->ccid3hctx_x_calc = tfrc_calc_x(hctx->ccid3hctx_s,
  						     hctx->ccid3hctx_rtt,
  						     hctx->ccid3hctx_p);
  		hctx->ccid3hctx_x = max_t(u32, min_t(u32, hctx->ccid3hctx_x_calc,
  							  2 * hctx->ccid3hctx_x_recv),
  					       (hctx->ccid3hctx_s /
  					        TFRC_MAX_BACK_OFF_TIME));
  	} else {
  		struct timeval now;
  
  		dccp_timestamp(sk, &now);
  	       	if (timeval_delta(&now, &hctx->ccid3hctx_t_ld) >=
  		    hctx->ccid3hctx_rtt) {
  			hctx->ccid3hctx_x = max_t(u32, min_t(u32, hctx->ccid3hctx_x_recv,
  								  hctx->ccid3hctx_x) * 2,
  						       usecs_div(hctx->ccid3hctx_s,
  							       	 hctx->ccid3hctx_rtt));
  			hctx->ccid3hctx_t_ld = now;
  		}
  	}
  }
  
  static void ccid3_hc_tx_no_feedback_timer(unsigned long data)
  {
  	struct sock *sk = (struct sock *)data;
  	unsigned long next_tmout = 0;
  	struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
  
  	bh_lock_sock(sk);
  	if (sock_owned_by_user(sk)) {
  		/* Try again later. */
  		/* XXX: set some sensible MIB */
  		sk_reset_timer(sk, &hctx->ccid3hctx_no_feedback_timer,
  			       jiffies + HZ / 5);
  		goto out;
  	}
  
  	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_TERM:
  		goto out;
  	case TFRC_SSTATE_NO_FBACK:
  		/* Halve send rate */
  		hctx->ccid3hctx_x /= 2;
  		if (hctx->ccid3hctx_x < (hctx->ccid3hctx_s /
  					 TFRC_MAX_BACK_OFF_TIME))
  			hctx->ccid3hctx_x = (hctx->ccid3hctx_s /
  					     TFRC_MAX_BACK_OFF_TIME);
  
  		ccid3_pr_debug("%s, sk=%p, state=%s, updated tx rate to %d "
  			       "bytes/s\n",
  			       dccp_role(sk), sk,
  			       ccid3_tx_state_name(hctx->ccid3hctx_state),
  			       hctx->ccid3hctx_x);
  		next_tmout = max_t(u32, 2 * usecs_div(hctx->ccid3hctx_s,
  						      hctx->ccid3hctx_x),
  					TFRC_INITIAL_TIMEOUT);
  		/*
  		 * FIXME - not sure above calculation is correct. See section
  		 * 5 of CCID3 11 should adjust tx_t_ipi and double that to
  		 * achieve it really
  		 */
  		break;
  	case TFRC_SSTATE_FBACK:
  		/*
  		 * Check if IDLE since last timeout and recv rate is less than
  		 * 4 packets per RTT
  		 */
  		if (!hctx->ccid3hctx_idle ||
  		    (hctx->ccid3hctx_x_recv >=
  		     4 * usecs_div(hctx->ccid3hctx_s, hctx->ccid3hctx_rtt))) {
  			ccid3_pr_debug("%s, sk=%p, state=%s, not idle\n",
  				       dccp_role(sk), sk,
  				       ccid3_tx_state_name(hctx->ccid3hctx_state));
  			/* Halve sending rate */
  
  			/*  If (X_calc > 2 * X_recv)
  			 *    X_recv = max(X_recv / 2, s / (2 * t_mbi));
  			 *  Else
  			 *    X_recv = X_calc / 4;
  			 */
  			BUG_ON(hctx->ccid3hctx_p >= TFRC_SMALLEST_P &&
  			       hctx->ccid3hctx_x_calc == 0);
  
  			/* check also if p is zero -> x_calc is infinity? */
  			if (hctx->ccid3hctx_p < TFRC_SMALLEST_P ||
  			    hctx->ccid3hctx_x_calc > 2 * hctx->ccid3hctx_x_recv)
  				hctx->ccid3hctx_x_recv = max_t(u32, hctx->ccid3hctx_x_recv / 2,
  								    hctx->ccid3hctx_s / (2 * TFRC_MAX_BACK_OFF_TIME));
  			else
  				hctx->ccid3hctx_x_recv = hctx->ccid3hctx_x_calc / 4;
  
  			/* Update sending rate */
  			ccid3_hc_tx_update_x(sk);
  		}
  		/*
  		 * Schedule no feedback timer to expire in
  		 * max(4 * R, 2 * s / X)
  		 */
  		next_tmout = max_t(u32, hctx->ccid3hctx_t_rto, 
  					2 * usecs_div(hctx->ccid3hctx_s,
  						      hctx->ccid3hctx_x));
  		break;
  	default:
  		printk(KERN_CRIT "%s: %s, sk=%p, Illegal state (%d)!\n",
  		       __FUNCTION__, dccp_role(sk), sk, hctx->ccid3hctx_state);
  		dump_stack();
  		goto out;
  	}
  
  	sk_reset_timer(sk, &hctx->ccid3hctx_no_feedback_timer, 
  		      jiffies + max_t(u32, 1, usecs_to_jiffies(next_tmout)));
  	hctx->ccid3hctx_idle = 1;
  out:
  	bh_unlock_sock(sk);
  	sock_put(sk);
  }
  
  static int ccid3_hc_tx_send_packet(struct sock *sk,
  				   struct sk_buff *skb, int len)
  {
  	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;
  	int rc = -ENOTCONN;
  
  	BUG_ON(hctx == NULL || hctx->ccid3hctx_state == TFRC_SSTATE_TERM);
  
  	/* Check if pure ACK or Terminating*/
  	/*
  	 * XXX: We only call this function for DATA and DATAACK, on, these
  	 * packets can have zero length, but why the comment about "pure ACK"?
  	 */
  	if (unlikely(len == 0))
  		goto out;
  
  	/* 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,
  						    SLAB_ATOMIC);
  
  		rc = -ENOBUFS;
  		if (unlikely(new_packet == NULL)) {
  			LIMIT_NETDEBUG(KERN_WARNING "%s: %s, sk=%p, not enough "
  				       "mem to add to history, send refused\n",
  				       __FUNCTION__, dccp_role(sk), sk);
  			goto out;
  		}
  
  		dccp_tx_hist_add_entry(&hctx->ccid3hctx_hist, new_packet);
  	}
  
  	dccp_timestamp(sk, &now);
  
  	switch (hctx->ccid3hctx_state) {
  	case TFRC_SSTATE_NO_SENT:
  		hctx->ccid3hctx_no_feedback_timer.function = ccid3_hc_tx_no_feedback_timer;
  		hctx->ccid3hctx_no_feedback_timer.data     = (unsigned long)sk;
  		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);
  		hctx->ccid3hctx_t_ipi = TFRC_INITIAL_IPI;
  
  		/* Set nominal send time for initial packet */
  		hctx->ccid3hctx_t_nom = now;
  		timeval_add_usecs(&hctx->ccid3hctx_t_nom,
  				  hctx->ccid3hctx_t_ipi);
  		ccid3_calc_new_delta(hctx);
  		rc = 0;
  		break;
  	case TFRC_SSTATE_NO_FBACK:
  	case TFRC_SSTATE_FBACK:
  		delay = (timeval_delta(&now, &hctx->ccid3hctx_t_nom) -
  		         hctx->ccid3hctx_delta);
  		delay /= -1000;
  		/* divide by -1000 is to convert to ms and get sign right */
  		rc = delay > 0 ? delay : 0;
  		break;
  	default:
  		printk(KERN_CRIT "%s: %s, sk=%p, Illegal state (%d)!\n",
  		       __FUNCTION__, dccp_role(sk), sk, hctx->ccid3hctx_state);
  		dump_stack();
  		rc = -EINVAL;
  		break;
  	}
  
  	/* Can we send? if so add options and add to packet history */
  	if (rc == 0) {
  		dp->dccps_hc_tx_insert_options = 1;
  		new_packet->dccphtx_ccval =
  			DCCP_SKB_CB(skb)->dccpd_ccval =
  				hctx->ccid3hctx_last_win_count;
  	}
  out:
  	return rc;
  }
  
  static void ccid3_hc_tx_packet_sent(struct sock *sk, int more, int len)
  {
  	const struct dccp_sock *dp = dccp_sk(sk);
  	struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
  	struct timeval now;
  
  	BUG_ON(hctx == NULL || hctx->ccid3hctx_state == TFRC_SSTATE_TERM);
  
  	dccp_timestamp(sk, &now);
  
  	/* check if we have sent a data packet */
  	if (len > 0) {
  		unsigned long quarter_rtt;
  		struct dccp_tx_hist_entry *packet;
  
  		packet = dccp_tx_hist_head(&hctx->ccid3hctx_hist);
  		if (unlikely(packet == NULL)) {
  			LIMIT_NETDEBUG(KERN_WARNING "%s: packet doesn't "
  				       "exists in history!\n", __FUNCTION__);
  			return;
  		}
  		if (unlikely(packet->dccphtx_sent)) {
  			LIMIT_NETDEBUG(KERN_WARNING "%s: no unsent packet in "
  				       "history!\n", __FUNCTION__);
  			return;
  		}
  		packet->dccphtx_tstamp = now;
  		packet->dccphtx_seqno  = dp->dccps_gss;
  		/*
  		 * Check if win_count have changed
  		 * Algorithm in "8.1. Window Counter Valuer" in
  		 * draft-ietf-dccp-ccid3-11.txt
  		 */
  		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;
  	} else
  		ccid3_pr_debug("%s, sk=%p, seqno=%llu NOT inserted!\n",
  			       dccp_role(sk), sk, dp->dccps_gss);
  
  	switch (hctx->ccid3hctx_state) {
  	case TFRC_SSTATE_NO_SENT:
  		/* if first wasn't pure ack */
  		if (len != 0)
  			printk(KERN_CRIT "%s: %s, First packet sent is noted "
  					 "as a data packet\n",
  			       __FUNCTION__, dccp_role(sk));
  		return;
  	case TFRC_SSTATE_NO_FBACK:
  	case TFRC_SSTATE_FBACK:
  		if (len > 0) {
  			hctx->ccid3hctx_t_nom = now;
  			ccid3_calc_new_t_ipi(hctx);
  			ccid3_calc_new_delta(hctx);
  			timeval_add_usecs(&hctx->ccid3hctx_t_nom,
  					  hctx->ccid3hctx_t_ipi);
  		}
  		break;
  	default:
  		printk(KERN_CRIT "%s: %s, sk=%p, Illegal state (%d)!\n",
  		       __FUNCTION__, dccp_role(sk), sk, hctx->ccid3hctx_state);
  		dump_stack();
  		break;
  	}
  }
  
  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 next_tmout; 
  	u32 t_elapsed;
  	u32 pinv;
  	u32 x_recv;
  	u32 r_sample;
  
  	BUG_ON(hctx == NULL || hctx->ccid3hctx_state == TFRC_SSTATE_TERM);
  
  	/* 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;
  
  	t_elapsed = dp->dccps_options_received.dccpor_elapsed_time * 10;
  	x_recv = opt_recv->ccid3or_receive_rate;
  	pinv = opt_recv->ccid3or_loss_event_rate;
  
  	switch (hctx->ccid3hctx_state) {
  	case TFRC_SSTATE_NO_SENT:
  		/* FIXME: what to do here? */
  		return;
  	case TFRC_SSTATE_NO_FBACK:
  	case TFRC_SSTATE_FBACK:
  		/* Calculate new round trip sample by
  		 * R_sample = (now - t_recvdata) - t_delay */
  		/* get t_recvdata from history */
  		packet = dccp_tx_hist_find_entry(&hctx->ccid3hctx_hist,
  						 DCCP_SKB_CB(skb)->dccpd_ack_seq);
  		if (unlikely(packet == NULL)) {
  			LIMIT_NETDEBUG(KERN_WARNING "%s: %s, sk=%p, seqno "
  				       "%llu(%s) does't exist in history!\n",
  				       __FUNCTION__, 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 RTT */
  		dccp_timestamp(sk, &now);
  		r_sample = timeval_delta(&now, &packet->dccphtx_tstamp);
  		if (unlikely(r_sample <= t_elapsed))
  			LIMIT_NETDEBUG(KERN_WARNING "%s: r_sample=%uus, "
  				       "t_elapsed=%uus\n",
  				       __FUNCTION__, 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) {
  			ccid3_hc_tx_set_state(sk, TFRC_SSTATE_FBACK);
  			hctx->ccid3hctx_rtt = r_sample;
  		} else
  			hctx->ccid3hctx_rtt = (hctx->ccid3hctx_rtt * 9) / 10 +
  					      r_sample / 10;
  
  		ccid3_pr_debug("%s, sk=%p, New RTT estimate=%uus, "
  			       "r_sample=%us\n", dccp_role(sk), sk,
  			       hctx->ccid3hctx_rtt, r_sample);
  
  		/* Update timeout interval */
  		hctx->ccid3hctx_t_rto = max_t(u32, 4 * hctx->ccid3hctx_rtt,
  					      USEC_PER_SEC);
  
  		/* Update receive rate */
  		hctx->ccid3hctx_x_recv = x_recv;/* X_recv in bytes per sec */
  
  		/* Update loss event rate */
  		if (pinv == ~0 || pinv == 0)
  			hctx->ccid3hctx_p = 0;
  		else {
  			hctx->ccid3hctx_p = 1000000 / pinv;
  
  			if (hctx->ccid3hctx_p < TFRC_SMALLEST_P) {
  				hctx->ccid3hctx_p = TFRC_SMALLEST_P;
  				ccid3_pr_debug("%s, sk=%p, Smallest p used!\n",
  					       dccp_role(sk), sk);
  			}
  		}
  
  		/* unschedule no feedback timer */
  		sk_stop_timer(sk, &hctx->ccid3hctx_no_feedback_timer);
  
  		/* Update sending rate */
  		ccid3_hc_tx_update_x(sk);
  
  		/* Update next send time */
  		timeval_sub_usecs(&hctx->ccid3hctx_t_nom,
  				  hctx->ccid3hctx_t_ipi);
  		ccid3_calc_new_t_ipi(hctx);
  		timeval_add_usecs(&hctx->ccid3hctx_t_nom,
  				  hctx->ccid3hctx_t_ipi);
  		ccid3_calc_new_delta(hctx);
  
  		/* 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_ccids.
  		 */
  		sk->sk_write_space(sk);
  
  		/*
  		 * Schedule no feedback timer to expire in
  		 * max(4 * R, 2 * s / X)
  		 */
  		next_tmout = max(hctx->ccid3hctx_t_rto,
  				 2 * usecs_div(hctx->ccid3hctx_s,
  					       hctx->ccid3hctx_x));
  			
  		ccid3_pr_debug("%s, sk=%p, Scheduled no feedback timer to "
  			       "expire in %lu jiffies (%luus)\n",
  			       dccp_role(sk), sk,
  			       usecs_to_jiffies(next_tmout), next_tmout); 
  
  		sk_reset_timer(sk, &hctx->ccid3hctx_no_feedback_timer, 
  			       jiffies + max_t(u32, 1, usecs_to_jiffies(next_tmout)));
  
  		/* set idle flag */
  		hctx->ccid3hctx_idle = 1;   
  		break;
  	default:
  		printk(KERN_CRIT "%s: %s, sk=%p, Illegal state (%d)!\n",
  		       __FUNCTION__, dccp_role(sk), sk, hctx->ccid3hctx_state);
  		dump_stack();
  		break;
  	}
  }
  
  static void 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))
  		return;
  
  	 DCCP_SKB_CB(skb)->dccpd_ccval = hctx->ccid3hctx_last_win_count;
  }
  
  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)) {
  			LIMIT_NETDEBUG(KERN_WARNING "%s: %s, sk=%p, invalid "
  				       "len for TFRC_OPT_LOSS_EVENT_RATE\n",
  				       __FUNCTION__, dccp_role(sk), sk);
  			rc = -EINVAL;
  		} else {
  			opt_recv->ccid3or_loss_event_rate = ntohl(*(u32 *)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)) {
  			LIMIT_NETDEBUG(KERN_WARNING "%s: %s, sk=%p, invalid "
  				       "len for TFRC_OPT_RECEIVE_RATE\n",
  				       __FUNCTION__, dccp_role(sk), sk);
  			rc = -EINVAL;
  		} else {
  			opt_recv->ccid3or_receive_rate = ntohl(*(u32 *)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 sock *sk)
  {
  	struct dccp_sock *dp = dccp_sk(sk);
  	struct ccid3_hc_tx_sock *hctx;
  
  	dp->dccps_hc_tx_ccid_private = kmalloc(sizeof(*hctx), gfp_any());
  	if (dp->dccps_hc_tx_ccid_private == NULL)
  		return -ENOMEM;
  
  	hctx = ccid3_hc_tx_sk(sk);
  	memset(hctx, 0, sizeof(*hctx));
  
  	if (dp->dccps_packet_size >= TFRC_MIN_PACKET_SIZE &&
  	    dp->dccps_packet_size <= TFRC_MAX_PACKET_SIZE)
  		hctx->ccid3hctx_s = dp->dccps_packet_size;
  	else
  		hctx->ccid3hctx_s = TFRC_STD_PACKET_SIZE;
  
  	/* Set transmission rate to 1 packet per second */
  	hctx->ccid3hctx_x     = hctx->ccid3hctx_s;
  	hctx->ccid3hctx_t_rto = USEC_PER_SEC;
  	hctx->ccid3hctx_state = TFRC_SSTATE_NO_SENT;
  	INIT_LIST_HEAD(&hctx->ccid3hctx_hist);
  	init_timer(&hctx->ccid3hctx_no_feedback_timer);
  
  	return 0;
  }
  
  static void ccid3_hc_tx_exit(struct sock *sk)
  {
  	struct dccp_sock *dp = dccp_sk(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);
  
  	kfree(dp->dccps_hc_tx_ccid_private);
  	dp->dccps_hc_tx_ccid_private = NULL;
  }
  
  /*
   * RX Half Connection methods
   */
  
  /* TFRC receiver states */
  enum ccid3_hc_rx_states {
         	TFRC_RSTATE_NO_DATA = 1,
  	TFRC_RSTATE_DATA,
  	TFRC_RSTATE_TERM    = 127,
  };
  
  #ifdef 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 inline 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 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;
  	default:
  		printk(KERN_CRIT "%s: %s, sk=%p, Illegal state (%d)!\n",
  		       __FUNCTION__, dccp_role(sk), sk, hcrx->ccid3hcrx_state);
  		dump_stack();
  		return;
  	}
  
  	packet = dccp_rx_hist_find_data_packet(&hcrx->ccid3hcrx_hist);
  	if (unlikely(packet == NULL)) {
  		LIMIT_NETDEBUG(KERN_WARNING "%s: %s, sk=%p, no data packet "
  			       "in history!\n",
  			       __FUNCTION__, dccp_role(sk), sk);
  		return;
  	}
  
  	hcrx->ccid3hcrx_tstamp_last_feedback = now;
  	hcrx->ccid3hcrx_last_counter	     = packet->dccphrx_ccval;
  	hcrx->ccid3hcrx_seqno_last_counter   = packet->dccphrx_seqno;
  	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 = ~0;
  	else
  		hcrx->ccid3hcrx_pinv = 1000000 / hcrx->ccid3hcrx_p;
  	dp->dccps_hc_rx_insert_options = 1;
  	dccp_send_ack(sk);
  }
  
  static void ccid3_hc_rx_insert_options(struct sock *sk, struct sk_buff *skb)
  {
  	const struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);
  	u32 x_recv, pinv;
  
  	BUG_ON(hcrx == NULL);
  
  	if (!(sk->sk_state == DCCP_OPEN || sk->sk_state == DCCP_PARTOPEN))
  		return;
  
  	DCCP_SKB_CB(skb)->dccpd_ccval = hcrx->ccid3hcrx_last_counter;
  
  	if (dccp_packet_without_ack(skb))
  		return;
  		
  	if (hcrx->ccid3hcrx_elapsed_time != 0)
  		dccp_insert_option_elapsed_time(sk, skb,
  						hcrx->ccid3hcrx_elapsed_time);
  	dccp_insert_option_timestamp(sk, skb);
  	x_recv = htonl(hcrx->ccid3hcrx_x_recv);
  	pinv   = htonl(hcrx->ccid3hcrx_pinv);
  	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));
  }
  
  /* 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)) {
  		LIMIT_NETDEBUG(KERN_WARNING "%s: %s, sk=%p, packet history "
  			       "contains no data packets!\n",
  			       __FUNCTION__, dccp_role(sk), sk);
  		return ~0;
  	}
  
  	if (unlikely(interval == 0)) {
  		LIMIT_NETDEBUG(KERN_WARNING "%s: %s, sk=%p, Could not find a "
  			       "win_count interval > 0. Defaulting to 1\n",
  			       __FUNCTION__, dccp_role(sk), sk);
  		interval = 1;
  	}
  found:
  	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)
  		rtt = 1;
  
  	dccp_timestamp(sk, &tstamp);
  	delta = timeval_delta(&tstamp, &hcrx->ccid3hcrx_tstamp_last_feedback);
  	x_recv = usecs_div(hcrx->ccid3hcrx_bytes_recv, delta);
  
  	tmp1 = (u64)x_recv * (u64)rtt;
  	do_div(tmp1,10000000);
  	tmp2 = (u32)tmp1;
  	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);
  
  	if (seq_loss != DCCP_MAX_SEQNO + 1 &&
  	    list_empty(&hcrx->ccid3hcrx_li_hist)) {
  		struct dccp_li_hist_entry *li_tail;
  
  		li_tail = dccp_li_hist_interval_new(ccid3_li_hist,
  						    &hcrx->ccid3hcrx_li_hist,
  						    seq_loss, win_loss);
  		if (li_tail == NULL)
  			return;
  		li_tail->dccplih_interval = ccid3_hc_rx_calc_first_li(sk);
  	} else
  		    LIMIT_NETDEBUG(KERN_WARNING "%s: FIXME: find end of "
  				   "interval\n", __FUNCTION__);
  }
  
  static void ccid3_hc_rx_detect_loss(struct sock *sk)
  {
  	struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);
  	u8 win_loss;
  	const u64 seq_loss = dccp_rx_hist_detect_loss(&hcrx->ccid3hcrx_hist,
  						      &hcrx->ccid3hcrx_li_hist,
  						      &win_loss);
  
  	ccid3_hc_rx_update_li(sk, seq_loss, win_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;
  	u8 win_count;
  	u32 p_prev, r_sample, t_elapsed;
  	int ins;
  
  	BUG_ON(hcrx == NULL ||
  	       !(hcrx->ccid3hcrx_state == TFRC_RSTATE_NO_DATA ||
  		 hcrx->ccid3hcrx_state == TFRC_RSTATE_DATA));
  
  	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;
  		p_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))
  			LIMIT_NETDEBUG(KERN_WARNING "%s: r_sample=%uus, "
  				       "t_elapsed=%uus\n",
  				       __FUNCTION__, 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 (p_prev != hcrx->ccid3hcrx_rtt)
  			ccid3_pr_debug("%s, New RTT=%luus, 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, SLAB_ATOMIC);
  	if (unlikely(packet == NULL)) {
  		LIMIT_NETDEBUG(KERN_WARNING "%s: %s, sk=%p, Not enough mem to "
  				"add rx packet to history, consider it lost!\n",
  			       __FUNCTION__, dccp_role(sk), sk);
  		return;
  	}
  
  	win_count = packet->dccphrx_ccval;
  
  	ins = dccp_rx_hist_add_packet(ccid3_rx_hist, &hcrx->ccid3hcrx_hist,
  				      &hcrx->ccid3hcrx_li_hist, packet);
  
  	if (DCCP_SKB_CB(skb)->dccpd_type == DCCP_PKT_ACK)
  		return;
  
  	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 += skb->len -
  					      dccp_hdr(skb)->dccph_doff * 4;
  		if (ins != 0)
  			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;
  	default:
  		printk(KERN_CRIT "%s: %s, sk=%p, Illegal state (%d)!\n",
  		       __FUNCTION__, dccp_role(sk), sk, hcrx->ccid3hcrx_state);
  		dump_stack();
  		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));
  
  	ccid3_hc_rx_detect_loss(sk);
  	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;
  	}
  
  	if (hcrx->ccid3hcrx_p > p_prev) {
  		ccid3_hc_rx_send_feedback(sk);
  		return;
  	}
  }
  
  static int ccid3_hc_rx_init(struct sock *sk)
  {
  	struct dccp_sock *dp = dccp_sk(sk);
  	struct ccid3_hc_rx_sock *hcrx;
  
  	ccid3_pr_debug("%s, sk=%p\n", dccp_role(sk), sk);
  
  	dp->dccps_hc_rx_ccid_private = kmalloc(sizeof(*hcrx), gfp_any());
  	if (dp->dccps_hc_rx_ccid_private == NULL)
  		return -ENOMEM;
  
  	hcrx = ccid3_hc_rx_sk(sk);
  	memset(hcrx, 0, sizeof(*hcrx));
  
  	if (dp->dccps_packet_size >= TFRC_MIN_PACKET_SIZE &&
  	    dp->dccps_packet_size <= TFRC_MAX_PACKET_SIZE)
  		hcrx->ccid3hcrx_s = dp->dccps_packet_size;
  	else
  		hcrx->ccid3hcrx_s = TFRC_STD_PACKET_SIZE;
  
  	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_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);
  	struct dccp_sock *dp = dccp_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);
  
  	kfree(dp->dccps_hc_rx_ccid_private);
  	dp->dccps_hc_rx_ccid_private = NULL;
  }
  
  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 ccid3 = {
  	.ccid_id		   = 3,
  	.ccid_name		   = "ccid3",
  	.ccid_owner		   = THIS_MODULE,
  	.ccid_init		   = ccid3_init,
  	.ccid_exit		   = ccid3_exit,
  	.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_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,
  };
   
  module_param(ccid3_debug, int, 0444);
  MODULE_PARM_DESC(ccid3_debug, "Enable debug messages");
  
  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)
  {
  #ifdef CONFIG_IP_DCCP_UNLOAD_HACK
  	/*
  	 * Hack to use while developing, so that we get rid of the control
  	 * sock, that is what keeps a refcount on dccp.ko -acme
  	 */
  	extern void dccp_ctl_sock_exit(void);
  
  	dccp_ctl_sock_exit();
  #endif
  	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 <iam4@cs.waikato.ac.nz>, "
  	      "Arnaldo Carvalho de Melo <acme@ghostprotocols.net>");
  MODULE_DESCRIPTION("DCCP TFRC CCID3 CCID");
  MODULE_LICENSE("GPL");
  MODULE_ALIAS("net-dccp-ccid-3");
  