s0ph0s 3c77e076e2
Add support for negotiating IMAP and SMTP on the HTTPS port 443 using TLS ALPN "imap" and "smtp"
Intended for future use with chatmail servers. Standard email ports may be
blocked on some networks, while the HTTPS port may be accessible.

This is a squashed commit of PR #255 by s0ph0s-dog.
2025-01-23 11:16:20 +01:00

123 lines
4.5 KiB
Go

// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package http2
import (
"math"
"net/http"
"time"
)
// http2Config is a package-internal version of net/http.HTTP2Config.
//
// http.HTTP2Config was added in Go 1.24.
// When running with a version of net/http that includes HTTP2Config,
// we merge the configuration with the fields in Transport or Server
// to produce an http2Config.
//
// Zero valued fields in http2Config are interpreted as in the
// net/http.HTTPConfig documentation.
//
// Precedence order for reconciling configurations is:
//
// - Use the net/http.{Server,Transport}.HTTP2Config value, when non-zero.
// - Otherwise use the http2.{Server.Transport} value.
// - If the resulting value is zero or out of range, use a default.
type http2Config struct {
MaxConcurrentStreams uint32
MaxDecoderHeaderTableSize uint32
MaxEncoderHeaderTableSize uint32
MaxReadFrameSize uint32
MaxUploadBufferPerConnection int32
MaxUploadBufferPerStream int32
SendPingTimeout time.Duration
PingTimeout time.Duration
WriteByteTimeout time.Duration
PermitProhibitedCipherSuites bool
CountError func(errType string)
}
// configFromServer merges configuration settings from
// net/http.Server.HTTP2Config and http2.Server.
func configFromServer(h1 *http.Server, h2 *Server) http2Config {
conf := http2Config{
MaxConcurrentStreams: h2.MaxConcurrentStreams,
MaxEncoderHeaderTableSize: h2.MaxEncoderHeaderTableSize,
MaxDecoderHeaderTableSize: h2.MaxDecoderHeaderTableSize,
MaxReadFrameSize: h2.MaxReadFrameSize,
MaxUploadBufferPerConnection: h2.MaxUploadBufferPerConnection,
MaxUploadBufferPerStream: h2.MaxUploadBufferPerStream,
SendPingTimeout: h2.ReadIdleTimeout,
PingTimeout: h2.PingTimeout,
WriteByteTimeout: h2.WriteByteTimeout,
PermitProhibitedCipherSuites: h2.PermitProhibitedCipherSuites,
CountError: h2.CountError,
}
fillNetHTTPServerConfig(&conf, h1)
setConfigDefaults(&conf, true)
return conf
}
// configFromTransport merges configuration settings from h2 and h2.t1.HTTP2
// (the net/http Transport).
func configFromTransport(h2 *Transport) http2Config {
conf := http2Config{
MaxEncoderHeaderTableSize: h2.MaxEncoderHeaderTableSize,
MaxDecoderHeaderTableSize: h2.MaxDecoderHeaderTableSize,
MaxReadFrameSize: h2.MaxReadFrameSize,
SendPingTimeout: h2.ReadIdleTimeout,
PingTimeout: h2.PingTimeout,
WriteByteTimeout: h2.WriteByteTimeout,
}
// Unlike most config fields, where out-of-range values revert to the default,
// Transport.MaxReadFrameSize clips.
if conf.MaxReadFrameSize < minMaxFrameSize {
conf.MaxReadFrameSize = minMaxFrameSize
} else if conf.MaxReadFrameSize > maxFrameSize {
conf.MaxReadFrameSize = maxFrameSize
}
if h2.t1 != nil {
fillNetHTTPTransportConfig(&conf, h2.t1)
}
setConfigDefaults(&conf, false)
return conf
}
func setDefault[T ~int | ~int32 | ~uint32 | ~int64](v *T, minval, maxval, defval T) {
if *v < minval || *v > maxval {
*v = defval
}
}
func setConfigDefaults(conf *http2Config, server bool) {
setDefault(&conf.MaxConcurrentStreams, 1, math.MaxUint32, defaultMaxStreams)
setDefault(&conf.MaxEncoderHeaderTableSize, 1, math.MaxUint32, initialHeaderTableSize)
setDefault(&conf.MaxDecoderHeaderTableSize, 1, math.MaxUint32, initialHeaderTableSize)
if server {
setDefault(&conf.MaxUploadBufferPerConnection, initialWindowSize, math.MaxInt32, 1<<20)
} else {
setDefault(&conf.MaxUploadBufferPerConnection, initialWindowSize, math.MaxInt32, transportDefaultConnFlow)
}
if server {
setDefault(&conf.MaxUploadBufferPerStream, 1, math.MaxInt32, 1<<20)
} else {
setDefault(&conf.MaxUploadBufferPerStream, 1, math.MaxInt32, transportDefaultStreamFlow)
}
setDefault(&conf.MaxReadFrameSize, minMaxFrameSize, maxFrameSize, defaultMaxReadFrameSize)
setDefault(&conf.PingTimeout, 1, math.MaxInt64, 15*time.Second)
}
// adjustHTTP1MaxHeaderSize converts a limit in bytes on the size of an HTTP/1 header
// to an HTTP/2 MAX_HEADER_LIST_SIZE value.
func adjustHTTP1MaxHeaderSize(n int64) int64 {
// http2's count is in a slightly different unit and includes 32 bytes per pair.
// So, take the net/http.Server value and pad it up a bit, assuming 10 headers.
const perFieldOverhead = 32 // per http2 spec
const typicalHeaders = 10 // conservative
return n + typicalHeaders*perFieldOverhead
}