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77 lines
2.7 KiB
C
77 lines
2.7 KiB
C
/*
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* Copyright 2022-2023 The OpenSSL Project Authors. All Rights Reserved.
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*
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* Licensed under the Apache License 2.0 (the "License"). You may not use
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* this file except in compliance with the License. You can obtain a copy
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* in the file LICENSE in the source distribution or at
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* https://www.openssl.org/source/license.html
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*/
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#include "internal/quic_statm.h"
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void ossl_statm_update_rtt(OSSL_STATM *statm,
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OSSL_TIME ack_delay,
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OSSL_TIME override_latest_rtt)
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{
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OSSL_TIME adjusted_rtt, latest_rtt = override_latest_rtt;
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/* Use provided RTT value, or else last RTT value. */
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if (ossl_time_is_zero(latest_rtt))
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latest_rtt = statm->latest_rtt;
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else
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statm->latest_rtt = latest_rtt;
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if (!statm->have_first_sample) {
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statm->min_rtt = latest_rtt;
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statm->smoothed_rtt = latest_rtt;
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statm->rtt_variance = ossl_time_divide(latest_rtt, 2);
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statm->have_first_sample = 1;
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return;
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}
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/* Update minimum RTT. */
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if (ossl_time_compare(latest_rtt, statm->min_rtt) < 0)
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statm->min_rtt = latest_rtt;
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/*
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* Enforcement of max_ack_delay is the responsibility of
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* the caller as it is context-dependent.
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*/
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adjusted_rtt = latest_rtt;
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if (ossl_time_compare(latest_rtt, ossl_time_add(statm->min_rtt, ack_delay)) >= 0)
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adjusted_rtt = ossl_time_subtract(latest_rtt, ack_delay);
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statm->rtt_variance = ossl_time_divide(ossl_time_add(ossl_time_multiply(statm->rtt_variance, 3),
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ossl_time_abs_difference(statm->smoothed_rtt,
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adjusted_rtt)), 4);
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statm->smoothed_rtt = ossl_time_divide(ossl_time_add(ossl_time_multiply(statm->smoothed_rtt, 7),
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adjusted_rtt), 8);
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}
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/* RFC 9002 kInitialRtt value. RFC recommended value. */
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#define K_INITIAL_RTT ossl_ms2time(333)
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int ossl_statm_init(OSSL_STATM *statm)
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{
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statm->smoothed_rtt = K_INITIAL_RTT;
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statm->latest_rtt = ossl_time_zero();
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statm->min_rtt = ossl_time_infinite();
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statm->rtt_variance = ossl_time_divide(K_INITIAL_RTT, 2);
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statm->have_first_sample = 0;
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return 1;
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}
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void ossl_statm_destroy(OSSL_STATM *statm)
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{
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/* No-op. */
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}
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void ossl_statm_get_rtt_info(OSSL_STATM *statm, OSSL_RTT_INFO *rtt_info)
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{
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rtt_info->min_rtt = statm->min_rtt;
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rtt_info->latest_rtt = statm->latest_rtt;
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rtt_info->smoothed_rtt = statm->smoothed_rtt;
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rtt_info->rtt_variance = statm->rtt_variance;
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}
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