cubefs

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// Copyright 2014 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 http2
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import (
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	"net/http"
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	"sync"
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)
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var (
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	commonBuildOnce   sync.Once
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	commonLowerHeader map[string]string // Go-Canonical-Case -> lower-case
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	commonCanonHeader map[string]string // lower-case -> Go-Canonical-Case
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)
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func buildCommonHeaderMapsOnce() {
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	commonBuildOnce.Do(buildCommonHeaderMaps)
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}
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func buildCommonHeaderMaps() {
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	common := []string{
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		"accept",
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		"accept-charset",
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		"accept-encoding",
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		"accept-language",
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		"accept-ranges",
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		"age",
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		"access-control-allow-credentials",
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		"access-control-allow-headers",
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		"access-control-allow-methods",
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		"access-control-allow-origin",
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		"access-control-expose-headers",
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		"access-control-max-age",
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		"access-control-request-headers",
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		"access-control-request-method",
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		"allow",
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		"authorization",
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		"cache-control",
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		"content-disposition",
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		"content-encoding",
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		"content-language",
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		"content-length",
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		"content-location",
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		"content-range",
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		"content-type",
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		"cookie",
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		"date",
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		"etag",
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		"expect",
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		"expires",
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		"from",
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		"host",
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		"if-match",
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		"if-modified-since",
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		"if-none-match",
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		"if-unmodified-since",
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		"last-modified",
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		"link",
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		"location",
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		"max-forwards",
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		"origin",
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		"proxy-authenticate",
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		"proxy-authorization",
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		"range",
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		"referer",
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		"refresh",
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		"retry-after",
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		"server",
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		"set-cookie",
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		"strict-transport-security",
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		"trailer",
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		"transfer-encoding",
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		"user-agent",
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		"vary",
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		"via",
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		"www-authenticate",
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		"x-forwarded-for",
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		"x-forwarded-proto",
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	}
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	commonLowerHeader = make(map[string]string, len(common))
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	commonCanonHeader = make(map[string]string, len(common))
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	for _, v := range common {
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		chk := http.CanonicalHeaderKey(v)
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		commonLowerHeader[chk] = v
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		commonCanonHeader[v] = chk
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	}
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}
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func lowerHeader(v string) (lower string, ascii bool) {
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	buildCommonHeaderMapsOnce()
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	if s, ok := commonLowerHeader[v]; ok {
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		return s, true
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	}
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	return asciiToLower(v)
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}
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func canonicalHeader(v string) string {
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	buildCommonHeaderMapsOnce()
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	if s, ok := commonCanonHeader[v]; ok {
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		return s
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	}
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	return http.CanonicalHeaderKey(v)
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}
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