/src/openssl/ssl/quic/quic_statm.c
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1 | | /* |
2 | | * Copyright 2022-2023 The OpenSSL Project Authors. All Rights Reserved. |
3 | | * |
4 | | * Licensed under the Apache License 2.0 (the "License"). You may not use |
5 | | * this file except in compliance with the License. You can obtain a copy |
6 | | * in the file LICENSE in the source distribution or at |
7 | | * https://www.openssl.org/source/license.html |
8 | | */ |
9 | | |
10 | | #include "internal/quic_statm.h" |
11 | | |
12 | | void ossl_statm_update_rtt(OSSL_STATM *statm, |
13 | | OSSL_TIME ack_delay, |
14 | | OSSL_TIME override_latest_rtt) |
15 | 0 | { |
16 | 0 | OSSL_TIME adjusted_rtt, latest_rtt = override_latest_rtt; |
17 | | |
18 | | /* Use provided RTT value, or else last RTT value. */ |
19 | 0 | if (ossl_time_is_zero(latest_rtt)) |
20 | 0 | latest_rtt = statm->latest_rtt; |
21 | 0 | else |
22 | 0 | statm->latest_rtt = latest_rtt; |
23 | |
|
24 | 0 | if (!statm->have_first_sample) { |
25 | 0 | statm->min_rtt = latest_rtt; |
26 | 0 | statm->smoothed_rtt = latest_rtt; |
27 | 0 | statm->rtt_variance = ossl_time_divide(latest_rtt, 2); |
28 | 0 | statm->have_first_sample = 1; |
29 | 0 | return; |
30 | 0 | } |
31 | | |
32 | | /* Update minimum RTT. */ |
33 | 0 | if (ossl_time_compare(latest_rtt, statm->min_rtt) < 0) |
34 | 0 | statm->min_rtt = latest_rtt; |
35 | | |
36 | | /* |
37 | | * Enforcement of max_ack_delay is the responsibility of |
38 | | * the caller as it is context-dependent. |
39 | | */ |
40 | |
|
41 | 0 | adjusted_rtt = latest_rtt; |
42 | 0 | if (ossl_time_compare(latest_rtt, ossl_time_add(statm->min_rtt, ack_delay)) >= 0) |
43 | 0 | adjusted_rtt = ossl_time_subtract(latest_rtt, ack_delay); |
44 | |
|
45 | 0 | statm->rtt_variance = ossl_time_divide(ossl_time_add(ossl_time_multiply(statm->rtt_variance, 3), |
46 | 0 | ossl_time_abs_difference(statm->smoothed_rtt, |
47 | 0 | adjusted_rtt)), 4); |
48 | 0 | statm->smoothed_rtt = ossl_time_divide(ossl_time_add(ossl_time_multiply(statm->smoothed_rtt, 7), |
49 | 0 | adjusted_rtt), 8); |
50 | 0 | } |
51 | | |
52 | | /* RFC 9002 kInitialRtt value. RFC recommended value. */ |
53 | 0 | #define K_INITIAL_RTT ossl_ms2time(333) |
54 | | |
55 | | int ossl_statm_init(OSSL_STATM *statm) |
56 | 0 | { |
57 | 0 | statm->smoothed_rtt = K_INITIAL_RTT; |
58 | 0 | statm->latest_rtt = ossl_time_zero(); |
59 | 0 | statm->min_rtt = ossl_time_infinite(); |
60 | 0 | statm->rtt_variance = ossl_time_divide(K_INITIAL_RTT, 2); |
61 | 0 | statm->have_first_sample = 0; |
62 | 0 | return 1; |
63 | 0 | } |
64 | | |
65 | | void ossl_statm_destroy(OSSL_STATM *statm) |
66 | 0 | { |
67 | | /* No-op. */ |
68 | 0 | } |
69 | | |
70 | | void ossl_statm_get_rtt_info(OSSL_STATM *statm, OSSL_RTT_INFO *rtt_info) |
71 | 0 | { |
72 | 0 | rtt_info->min_rtt = statm->min_rtt; |
73 | 0 | rtt_info->latest_rtt = statm->latest_rtt; |
74 | 0 | rtt_info->smoothed_rtt = statm->smoothed_rtt; |
75 | 0 | rtt_info->rtt_variance = statm->rtt_variance; |
76 | 0 | } |