/*
  *  OpenVPN -- An application to securely tunnel IP networks
  *             over a single UDP port, with support for SSL/TLS-based
  *             session authentication and key exchange,
  *             packet encryption, packet authentication, and
  *             packet compression.
  *

  *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>

  *
  *  This program is free software; you can redistribute it and/or modify
  *  it under the terms of the GNU General Public License version 2
  *  as published by the Free Software Foundation.
  *
  *  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.,
  *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.

  */
 
 #ifndef SHAPER_H
 #define SHAPER_H
 
 /*#define SHAPER_DEBUG*/
 

 #ifdef ENABLE_FEATURE_SHAPER

 
 #include "basic.h"
 #include "integer.h"
 #include "misc.h"
 #include "error.h"
 #include "interval.h"
 
 /*
  * A simple traffic shaper for
  * the output direction.
  */
 
 #define SHAPER_MIN 100          /* bytes per second */
 #define SHAPER_MAX 100000000
 
 #define SHAPER_MAX_TIMEOUT 10   /* seconds */
 
 #define SHAPER_USE_FP
 

 struct shaper

 {

     int bytes_per_second;
     struct timeval wakeup;

 
 #ifdef SHAPER_USE_FP

     double factor;

 #else

     int factor;

 #endif
 };
 

 void shaper_msg(struct shaper *s);
 
 void shaper_reset_wakeup(struct shaper *s);

 
 /*
  * We want to wake up in delay microseconds.  If timeval is larger
  * than delay, set timeval to delay.
  */

 bool shaper_soonest_event(struct timeval *tv, int delay);

 
 /*
  * inline functions
  */
 
 static inline void

 shaper_reset(struct shaper *s, int bytes_per_second)

 {

     s->bytes_per_second = constrain_int(bytes_per_second, SHAPER_MIN, SHAPER_MAX);

 
 #ifdef SHAPER_USE_FP

     s->factor = 1000000.0 / (double)s->bytes_per_second;

 #else

     s->factor = 1000000 / s->bytes_per_second;

 #endif
 }
 
 static inline void

 shaper_init(struct shaper *s, int bytes_per_second)

 {

     shaper_reset(s, bytes_per_second);
     shaper_reset_wakeup(s);

 }
 
 static inline int

 shaper_current_bandwidth(struct shaper *s)

 {

     return s->bytes_per_second;

 }
 
 /*
  * Returns traffic shaping delay in microseconds relative to current
  * time, or 0 if no delay.
  */
 static inline int

 shaper_delay(struct shaper *s)

 {

     struct timeval tv;
     int delay = 0;

     if (tv_defined(&s->wakeup))

     {

         ASSERT(!openvpn_gettimeofday(&tv, NULL));
         delay = tv_subtract(&s->wakeup, &tv, SHAPER_MAX_TIMEOUT);

 #ifdef SHAPER_DEBUG

         dmsg(D_SHAPER_DEBUG, "SHAPER shaper_delay delay=%d", delay);

 #endif
     }
 

     return delay > 0 ? delay : 0;

 }
 
 
 /*
  * We are about to send a datagram of nbytes bytes.
  *
  * Compute when we can send another datagram,
  * based on target throughput (s->bytes_per_second).
  */
 static inline void

 shaper_wrote_bytes(struct shaper *s, int nbytes)

 {

     struct timeval tv;

     /* compute delay in microseconds */
     tv.tv_sec = 0;

 #ifdef SHAPER_USE_FP

     tv.tv_usec = min_int((int)((double)max_int(nbytes, 100) * s->factor), (SHAPER_MAX_TIMEOUT*1000000));

 #else

     tv.tv_usec = s->bytes_per_second
                  ? min_int(max_int(nbytes, 100) * s->factor, (SHAPER_MAX_TIMEOUT*1000000))
                  : 0;

 #endif
 

     if (tv.tv_usec)

     {

         ASSERT(!openvpn_gettimeofday(&s->wakeup, NULL));
         tv_add(&s->wakeup, &tv);

 
 #ifdef SHAPER_DEBUG

         dmsg(D_SHAPER_DEBUG, "SHAPER shaper_wrote_bytes bytes=%d delay=%ld sec=%"PRIi64" usec=%ld",

              nbytes,

              (long)tv.tv_usec,

              (int64_t)s->wakeup.tv_sec,

              (long)s->wakeup.tv_usec);

 #endif
     }
 }
 
 #if 0
 /*
  * Increase/Decrease bandwidth by a percentage.
  *
  * Return true if bandwidth changed.
  */
 static inline bool

 shaper_change_pct(struct shaper *s, int pct)

 {

     const int orig_bandwidth = s->bytes_per_second;
     const int new_bandwidth = orig_bandwidth + (orig_bandwidth * pct / 100);
     ASSERT(s->bytes_per_second);
     shaper_reset(s, new_bandwidth);
     return s->bytes_per_second != orig_bandwidth;

 }
 #endif
 

 #endif /* ENABLE_FEATURE_SHAPER */

 #endif /* ifndef SHAPER_H */