niki/vendor/golang.org/x/net/http/httpguts/guts.go

// Copyright 2018 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 httpguts provides functions implementing various details

// of the HTTP specification.

//

// This package is shared by the standard library (which vendors it)

// and x/net/http2. It comes with no API stability promise.

package httpguts

import (
	"net/textproto"
	"strings"
)

// ValidTrailerHeader reports whether name is a valid header field name to appear

// in trailers.

// See RFC 7230, Section 4.1.2

func ValidTrailerHeader(name string) bool {

	name = textproto.CanonicalMIMEHeaderKey(name)

	if strings.HasPrefix(name, "If-") || badTrailer[name] {

		return false

	}

	return true

}

var badTrailer = map[string]bool{

	"Authorization": true,

	"Cache-Control": true,

	"Connection": true,

	"Content-Encoding": true,

	"Content-Length": true,

	"Content-Range": true,

	"Content-Type": true,

	"Expect": true,

	"Host": true,

	"Keep-Alive": true,

	"Max-Forwards": true,

	"Pragma": true,

	"Proxy-Authenticate": true,

	"Proxy-Authorization": true,

	"Proxy-Connection": true,

	"Range": true,

	"Realm": true,

	"Te": true,

	"Trailer": true,

	"Transfer-Encoding": true,

	"Www-Authenticate": true,
}