netramesh

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// Copyright 2016 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package http
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import (
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	"io"
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	"strconv"
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	"strings"
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	"time"
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	"unicode/utf8"
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	"golang.org/x/net/http/httpguts"
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)
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// maxInt64 is the effective "infinite" value for the Server and
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// Transport's byte-limiting readers.
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const maxInt64 = 1<<63 - 1
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// aLongTimeAgo is a non-zero time, far in the past, used for
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// immediate cancelation of network operations.
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var aLongTimeAgo = time.Unix(1, 0)
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// TODO(bradfitz): move common stuff here. The other files have accumulated
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// generic http stuff in random places.
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// contextKey is a value for use with context.WithValue. It's used as
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// a pointer so it fits in an interface{} without allocation.
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type contextKey struct {
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	name string
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}
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func (k *contextKey) String() string { return "net/http context value " + k.name }
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// Given a string of the form "host", "host:port", or "[ipv6::address]:port",
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// return true if the string includes a port.
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func hasPort(s string) bool { return strings.LastIndex(s, ":") > strings.LastIndex(s, "]") }
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// removeEmptyPort strips the empty port in ":port" to ""
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// as mandated by RFC 3986 Section 6.2.3.
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func removeEmptyPort(host string) string {
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	if hasPort(host) {
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		return strings.TrimSuffix(host, ":")
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	}
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	return host
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}
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func isNotToken(r rune) bool {
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	return !httpguts.IsTokenRune(r)
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}
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func isASCII(s string) bool {
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	for i := 0; i < len(s); i++ {
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		if s[i] >= utf8.RuneSelf {
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			return false
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		}
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	}
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	return true
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}
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func hexEscapeNonASCII(s string) string {
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	newLen := 0
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	for i := 0; i < len(s); i++ {
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		if s[i] >= utf8.RuneSelf {
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			newLen += 3
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		} else {
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			newLen++
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		}
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	}
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	if newLen == len(s) {
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		return s
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	}
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	b := make([]byte, 0, newLen)
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	for i := 0; i < len(s); i++ {
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		if s[i] >= utf8.RuneSelf {
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			b = append(b, '%')
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			b = strconv.AppendInt(b, int64(s[i]), 16)
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		} else {
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			b = append(b, s[i])
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		}
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	}
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	return string(b)
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}
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// NoBody is an io.ReadCloser with no bytes. Read always returns EOF
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// and Close always returns nil. It can be used in an outgoing client
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// request to explicitly signal that a request has zero bytes.
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// An alternative, however, is to simply set Request.Body to nil.
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var NoBody = noBody{}
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type noBody struct{}
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func (noBody) Read([]byte) (int, error)         { return 0, io.EOF }
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func (noBody) Close() error                     { return nil }
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func (noBody) WriteTo(io.Writer) (int64, error) { return 0, nil }
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var (
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	// verify that an io.Copy from NoBody won't require a buffer:
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	_ io.WriterTo   = NoBody
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	_ io.ReadCloser = NoBody
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)
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// PushOptions describes options for Pusher.Push.
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type PushOptions struct {
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	// Method specifies the HTTP method for the promised request.
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	// If set, it must be "GET" or "HEAD". Empty means "GET".
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	Method string
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	// Header specifies additional promised request headers. This cannot
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	// include HTTP/2 pseudo header fields like ":path" and ":scheme",
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	// which will be added automatically.
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	Header Header
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}
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// Pusher is the interface implemented by ResponseWriters that support
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// HTTP/2 server push. For more background, see
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// https://tools.ietf.org/html/rfc7540#section-8.2.
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type Pusher interface {
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	// Push initiates an HTTP/2 server push. This constructs a synthetic
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	// request using the given target and options, serializes that request
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	// into a PUSH_PROMISE frame, then dispatches that request using the
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	// server's request handler. If opts is nil, default options are used.
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	//
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	// The target must either be an absolute path (like "/path") or an absolute
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	// URL that contains a valid host and the same scheme as the parent request.
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	// If the target is a path, it will inherit the scheme and host of the
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	// parent request.
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	//
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	// The HTTP/2 spec disallows recursive pushes and cross-authority pushes.
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	// Push may or may not detect these invalid pushes; however, invalid
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	// pushes will be detected and canceled by conforming clients.
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	//
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	// Handlers that wish to push URL X should call Push before sending any
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	// data that may trigger a request for URL X. This avoids a race where the
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	// client issues requests for X before receiving the PUSH_PROMISE for X.
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	//
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	// Push returns ErrNotSupported if the client has disabled push or if push
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	// is not supported on the underlying connection.
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	Push(target string, opts *PushOptions) error
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}
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