/src/unbound/util/rtt.c

Source (jump to first uncovered line)
/*
 * util/rtt.c - UDP round trip time estimator for resend timeouts.
 *
 * Copyright (c) 2007, NLnet Labs. All rights reserved.
 *
 * This software is open source.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 
 * Redistributions of source code must retain the above copyright notice,
 * this list of conditions and the following disclaimer.
 * 
 * Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 * 
 * Neither the name of the NLNET LABS nor the names of its contributors may
 * be used to endorse or promote products derived from this software without
 * specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
 * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/**
 * \file
 *
 * This file contains a data type and functions to help estimate good
 * round trip times for UDP resend timeout values.
 */
#include "config.h"
#include "util/rtt.h"
#include "iterator/iterator.h"

/* overwritten by config: infra_cache_min_rtt: */
int RTT_MIN_TIMEOUT = 50;
/* overwritten by config: infra_cache_max_rtt: */
int RTT_MAX_TIMEOUT = 120000;

/** calculate RTO from rtt information */
static int
calc_rto(const struct rtt_info* rtt)
{
  /* From Stevens, Unix Network Programming, Vol1, 3rd ed., p.598 */
  int rto = rtt->srtt + 4*rtt->rttvar;
  if(rto < RTT_MIN_TIMEOUT)
    rto = RTT_MIN_TIMEOUT;
  if(rto > RTT_MAX_TIMEOUT)
    rto = RTT_MAX_TIMEOUT;
  return rto;
}

void 
rtt_init(struct rtt_info* rtt)
{
  rtt->srtt = 0;
  rtt->rttvar = UNKNOWN_SERVER_NICENESS/4;
  rtt->rto = calc_rto(rtt);
  /* default value from the book is 0 + 4*0.75 = 3 seconds */
  /* first RTO is 0 + 4*0.094 = 0.376 seconds */
}

int 
rtt_timeout(const struct rtt_info* rtt)
{
  return rtt->rto;
}

int 
rtt_unclamped(const struct rtt_info* rtt)
{
  if(calc_rto(rtt) != rtt->rto) {
    /* timeout fallback has happened */
    return rtt->rto;
  }
  /* return unclamped value */
  return rtt->srtt + 4*rtt->rttvar;
}

void 
rtt_update(struct rtt_info* rtt, int ms)
{
  int delta = ms - rtt->srtt;
  rtt->srtt += delta / 8; /* g = 1/8 */
  if(delta < 0)
    delta = -delta; /* |delta| */
  rtt->rttvar += (delta - rtt->rttvar) / 4; /* h = 1/4 */
  rtt->rto = calc_rto(rtt);
}

void 
rtt_lost(struct rtt_info* rtt, int orig)
{
  /* exponential backoff */

  /* if a query succeeded and put down the rto meanwhile, ignore this */
  if(rtt->rto < orig)
    return;

  /* the original rto is doubled, not the current one to make sure
   * that the values in the cache are not increased by lots of
   * queries simultaneously as they time out at the same time */
  orig *= 2;
  if(rtt->rto <= orig) {
    rtt->rto = orig;
    if(rtt->rto > RTT_MAX_TIMEOUT)
      rtt->rto = RTT_MAX_TIMEOUT;
  }
}

int rtt_notimeout(const struct rtt_info* rtt)
{
  return calc_rto(rtt);
}

Line	Count	Source (jump to first uncovered line)
1		/*
2		* util/rtt.c - UDP round trip time estimator for resend timeouts.
3		*
4		* Copyright (c) 2007, NLnet Labs. All rights reserved.
5		*
6		* This software is open source.
7		*
8		* Redistribution and use in source and binary forms, with or without
9		* modification, are permitted provided that the following conditions
10		* are met:
11		*
12		* Redistributions of source code must retain the above copyright notice,
13		* this list of conditions and the following disclaimer.
14		*
15		* Redistributions in binary form must reproduce the above copyright notice,
16		* this list of conditions and the following disclaimer in the documentation
17		* and/or other materials provided with the distribution.
18		*
19		* Neither the name of the NLNET LABS nor the names of its contributors may
20		* be used to endorse or promote products derived from this software without
21		* specific prior written permission.
22		*
23		* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
24		* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
25		* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
26		* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
27		* HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
28		* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
29		* TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
30		* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
31		* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
32		* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
33		* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
34		*/
35
36		/**
37		* \file
38		*
39		* This file contains a data type and functions to help estimate good
40		* round trip times for UDP resend timeout values.
41		*/
42		#include "config.h"
43		#include "util/rtt.h"
44		#include "iterator/iterator.h"
45
46		/* overwritten by config: infra_cache_min_rtt: */
47		int RTT_MIN_TIMEOUT = 50;
48		/* overwritten by config: infra_cache_max_rtt: */
49		int RTT_MAX_TIMEOUT = 120000;
50
51		/** calculate RTO from rtt information */
52		static int
53		calc_rto(const struct rtt_info* rtt)
54	0	{
55		/* From Stevens, Unix Network Programming, Vol1, 3rd ed., p.598 */
56	0	int rto = rtt->srtt + 4*rtt->rttvar;
57	0	if(rto < RTT_MIN_TIMEOUT)
58	0	rto = RTT_MIN_TIMEOUT;
59	0	if(rto > RTT_MAX_TIMEOUT)
60	0	rto = RTT_MAX_TIMEOUT;
61	0	return rto;
62	0	}
63
64		void
65		rtt_init(struct rtt_info* rtt)
66	0	{
67	0	rtt->srtt = 0;
68	0	rtt->rttvar = UNKNOWN_SERVER_NICENESS/4;
69	0	rtt->rto = calc_rto(rtt);
70		/* default value from the book is 0 + 40.75 = 3 seconds /
71		/* first RTO is 0 + 40.094 = 0.376 seconds /
72	0	}
73
74		int
75		rtt_timeout(const struct rtt_info* rtt)
76	0	{
77	0	return rtt->rto;
78	0	}
79
80		int
81		rtt_unclamped(const struct rtt_info* rtt)
82	0	{
83	0	if(calc_rto(rtt) != rtt->rto) {
84		/* timeout fallback has happened */
85	0	return rtt->rto;
86	0	}
87		/* return unclamped value */
88	0	return rtt->srtt + 4*rtt->rttvar;
89	0	}
90
91		void
92		rtt_update(struct rtt_info* rtt, int ms)
93	0	{
94	0	int delta = ms - rtt->srtt;
95	0	rtt->srtt += delta / 8; /* g = 1/8 */
96	0	if(delta < 0)
97	0	delta = -delta; /* \|delta\| */
98	0	rtt->rttvar += (delta - rtt->rttvar) / 4; /* h = 1/4 */
99	0	rtt->rto = calc_rto(rtt);
100	0	}
101
102		void
103		rtt_lost(struct rtt_info* rtt, int orig)
104	0	{
105		/* exponential backoff */
106
107		/* if a query succeeded and put down the rto meanwhile, ignore this */
108	0	if(rtt->rto < orig)
109	0	return;
110
111		/* the original rto is doubled, not the current one to make sure
112		* that the values in the cache are not increased by lots of
113		* queries simultaneously as they time out at the same time */
114	0	orig *= 2;
115	0	if(rtt->rto <= orig) {
116	0	rtt->rto = orig;
117	0	if(rtt->rto > RTT_MAX_TIMEOUT)
118	0	rtt->rto = RTT_MAX_TIMEOUT;
119	0	}
120	0	}
121
122		int rtt_notimeout(const struct rtt_info* rtt)
123	0	{
124	0	return calc_rto(rtt);
125	0	}

Coverage Report

Created: 2025-07-11 06:08