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// Copyright 2016 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.
//go:generate bundle -o=h2_bundle.go -prefix=http2 -tags=!nethttpomithttp2
package http
import (
// incomparable is a zero-width, non-comparable type. Adding it to a struct
// makes that struct also non-comparable, and generally doesn't add
// any size (as long as it's first).
type incomparable [0]func()
// maxInt64 is the effective "infinite" value for the Server and
// Transport's byte-limiting readers.
const maxInt64 = 1<<63 - 1
// aLongTimeAgo is a non-zero time, far in the past, used for
// immediate cancellation of network operations.
var aLongTimeAgo = time.Unix(1, 0)
// omitBundledHTTP2 is set by omithttp2.go when the nethttpomithttp2
// build tag is set. That means h2_bundle.go isn't compiled in and we
// shouldn't try to use it.
var omitBundledHTTP2 bool
// TODO(bradfitz): move common stuff here. The other files have accumulated
// generic http stuff in random places.
// contextKey is a value for use with context.WithValue. It's used as
// a pointer so it fits in an interface{} without allocation.
type contextKey struct {
name string
func (k *contextKey) String() string { return "net/http context value " + }
// Given a string of the form "host", "host:port", or "[ipv6::address]:port",
// return true if the string includes a port.
func hasPort(s string) bool { return strings.LastIndex(s, ":") > strings.LastIndex(s, "]") }
// removeEmptyPort strips the empty port in ":port" to ""
// as mandated by RFC 3986 Section 6.2.3.
func removeEmptyPort(host string) string {
if hasPort(host) {
return strings.TrimSuffix(host, ":")
return host
func isNotToken(r rune) bool {
return !httpguts.IsTokenRune(r)
func isASCII(s string) bool {
for i := 0; i < len(s); i++ {
if s[i] >= utf8.RuneSelf {
return false
return true
// stringContainsCTLByte reports whether s contains any ASCII control character.
func stringContainsCTLByte(s string) bool {
for i := 0; i < len(s); i++ {
b := s[i]
if b < ' ' || b == 0x7f {
return true
return false
func hexEscapeNonASCII(s string) string {
newLen := 0
for i := 0; i < len(s); i++ {
if s[i] >= utf8.RuneSelf {
newLen += 3
} else {
if newLen == len(s) {
return s
b := make([]byte, 0, newLen)
for i := 0; i < len(s); i++ {
if s[i] >= utf8.RuneSelf {
b = append(b, '%')
b = strconv.AppendInt(b, int64(s[i]), 16)
} else {
b = append(b, s[i])
return string(b)
// NoBody is an io.ReadCloser with no bytes. Read always returns EOF
// and Close always returns nil. It can be used in an outgoing client
// request to explicitly signal that a request has zero bytes.
// An alternative, however, is to simply set Request.Body to nil.
var NoBody = noBody{}
type noBody struct{}
func (noBody) Read([]byte) (int, error) { return 0, io.EOF }
func (noBody) Close() error { return nil }
func (noBody) WriteTo(io.Writer) (int64, error) { return 0, nil }
var (
// verify that an io.Copy from NoBody won't require a buffer:
_ io.WriterTo = NoBody
_ io.ReadCloser = NoBody
// PushOptions describes options for Pusher.Push.
type PushOptions struct {
// Method specifies the HTTP method for the promised request.
// If set, it must be "GET" or "HEAD". Empty means "GET".
Method string
// Header specifies additional promised request headers. This cannot
// include HTTP/2 pseudo header fields like ":path" and ":scheme",
// which will be added automatically.
Header Header
// Pusher is the interface implemented by ResponseWriters that support
// HTTP/2 server push. For more background, see
type Pusher interface {
// Push initiates an HTTP/2 server push. This constructs a synthetic
// request using the given target and options, serializes that request
// into a PUSH_PROMISE frame, then dispatches that request using the
// server's request handler. If opts is nil, default options are used.
// The target must either be an absolute path (like "/path") or an absolute
// URL that contains a valid host and the same scheme as the parent request.
// If the target is a path, it will inherit the scheme and host of the
// parent request.
// The HTTP/2 spec disallows recursive pushes and cross-authority pushes.
// Push may or may not detect these invalid pushes; however, invalid
// pushes will be detected and canceled by conforming clients.
// Handlers that wish to push URL X should call Push before sending any
// data that may trigger a request for URL X. This avoids a race where the
// client issues requests for X before receiving the PUSH_PROMISE for X.
// Push will run in a separate goroutine making the order of arrival
// non-deterministic. Any required synchronization needs to be implemented
// by the caller.
// Push returns ErrNotSupported if the client has disabled push or if push
// is not supported on the underlying connection.
Push(target string, opts *PushOptions) error