1// Copyright 2024 The Go Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style
3// license that can be found in the LICENSE file.
4
5package http2
6
7import (
8 "math"
9 "net/http"
10 "time"
11)
12
13// http2Config is a package-internal version of net/http.HTTP2Config.
14//
15// http.HTTP2Config was added in Go 1.24.
16// When running with a version of net/http that includes HTTP2Config,
17// we merge the configuration with the fields in Transport or Server
18// to produce an http2Config.
19//
20// Zero valued fields in http2Config are interpreted as in the
21// net/http.HTTPConfig documentation.
22//
23// Precedence order for reconciling configurations is:
24//
25// - Use the net/http.{Server,Transport}.HTTP2Config value, when non-zero.
26// - Otherwise use the http2.{Server.Transport} value.
27// - If the resulting value is zero or out of range, use a default.
28type http2Config struct {
29 MaxConcurrentStreams uint32
30 MaxDecoderHeaderTableSize uint32
31 MaxEncoderHeaderTableSize uint32
32 MaxReadFrameSize uint32
33 MaxUploadBufferPerConnection int32
34 MaxUploadBufferPerStream int32
35 SendPingTimeout time.Duration
36 PingTimeout time.Duration
37 WriteByteTimeout time.Duration
38 PermitProhibitedCipherSuites bool
39 CountError func(errType string)
40}
41
42// configFromServer merges configuration settings from
43// net/http.Server.HTTP2Config and http2.Server.
44func configFromServer(h1 *http.Server, h2 *Server) http2Config {
45 conf := http2Config{
46 MaxConcurrentStreams: h2.MaxConcurrentStreams,
47 MaxEncoderHeaderTableSize: h2.MaxEncoderHeaderTableSize,
48 MaxDecoderHeaderTableSize: h2.MaxDecoderHeaderTableSize,
49 MaxReadFrameSize: h2.MaxReadFrameSize,
50 MaxUploadBufferPerConnection: h2.MaxUploadBufferPerConnection,
51 MaxUploadBufferPerStream: h2.MaxUploadBufferPerStream,
52 SendPingTimeout: h2.ReadIdleTimeout,
53 PingTimeout: h2.PingTimeout,
54 WriteByteTimeout: h2.WriteByteTimeout,
55 PermitProhibitedCipherSuites: h2.PermitProhibitedCipherSuites,
56 CountError: h2.CountError,
57 }
58 fillNetHTTPServerConfig(&conf, h1)
59 setConfigDefaults(&conf, true)
60 return conf
61}
62
63// configFromTransport merges configuration settings from h2 and h2.t1.HTTP2
64// (the net/http Transport).
65func configFromTransport(h2 *Transport) http2Config {
66 conf := http2Config{
67 MaxEncoderHeaderTableSize: h2.MaxEncoderHeaderTableSize,
68 MaxDecoderHeaderTableSize: h2.MaxDecoderHeaderTableSize,
69 MaxReadFrameSize: h2.MaxReadFrameSize,
70 SendPingTimeout: h2.ReadIdleTimeout,
71 PingTimeout: h2.PingTimeout,
72 WriteByteTimeout: h2.WriteByteTimeout,
73 }
74
75 // Unlike most config fields, where out-of-range values revert to the default,
76 // Transport.MaxReadFrameSize clips.
77 if conf.MaxReadFrameSize < minMaxFrameSize {
78 conf.MaxReadFrameSize = minMaxFrameSize
79 } else if conf.MaxReadFrameSize > maxFrameSize {
80 conf.MaxReadFrameSize = maxFrameSize
81 }
82
83 if h2.t1 != nil {
84 fillNetHTTPTransportConfig(&conf, h2.t1)
85 }
86 setConfigDefaults(&conf, false)
87 return conf
88}
89
90func setDefault[T ~int | ~int32 | ~uint32 | ~int64](v *T, minval, maxval, defval T) {
91 if *v < minval || *v > maxval {
92 *v = defval
93 }
94}
95
96func setConfigDefaults(conf *http2Config, server bool) {
97 setDefault(&conf.MaxConcurrentStreams, 1, math.MaxUint32, defaultMaxStreams)
98 setDefault(&conf.MaxEncoderHeaderTableSize, 1, math.MaxUint32, initialHeaderTableSize)
99 setDefault(&conf.MaxDecoderHeaderTableSize, 1, math.MaxUint32, initialHeaderTableSize)
100 if server {
101 setDefault(&conf.MaxUploadBufferPerConnection, initialWindowSize, math.MaxInt32, 1<<20)
102 } else {
103 setDefault(&conf.MaxUploadBufferPerConnection, initialWindowSize, math.MaxInt32, transportDefaultConnFlow)
104 }
105 if server {
106 setDefault(&conf.MaxUploadBufferPerStream, 1, math.MaxInt32, 1<<20)
107 } else {
108 setDefault(&conf.MaxUploadBufferPerStream, 1, math.MaxInt32, transportDefaultStreamFlow)
109 }
110 setDefault(&conf.MaxReadFrameSize, minMaxFrameSize, maxFrameSize, defaultMaxReadFrameSize)
111 setDefault(&conf.PingTimeout, 1, math.MaxInt64, 15*time.Second)
112}
113
114// adjustHTTP1MaxHeaderSize converts a limit in bytes on the size of an HTTP/1 header
115// to an HTTP/2 MAX_HEADER_LIST_SIZE value.
116func adjustHTTP1MaxHeaderSize(n int64) int64 {
117 // http2's count is in a slightly different unit and includes 32 bytes per pair.
118 // So, take the net/http.Server value and pad it up a bit, assuming 10 headers.
119 const perFieldOverhead = 32 // per http2 spec
120 const typicalHeaders = 10 // conservative
121 return n + typicalHeaders*perFieldOverhead
122}