headermap.go

Documentation: golang.org/x/net/http2

     1  // Copyright 2014 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package http2
     6  
     7  import (
     8  	"net/http"
     9  	"sync"
    10  )
    11  
    12  var (
    13  	commonBuildOnce   sync.Once
    14  	commonLowerHeader map[string]string // Go-Canonical-Case -> lower-case
    15  	commonCanonHeader map[string]string // lower-case -> Go-Canonical-Case
    16  )
    17  
    18  func buildCommonHeaderMapsOnce() {
    19  	commonBuildOnce.Do(buildCommonHeaderMaps)
    20  }
    21  
    22  func buildCommonHeaderMaps() {
    23  	common := []string{
    24  		"accept",
    25  		"accept-charset",
    26  		"accept-encoding",
    27  		"accept-language",
    28  		"accept-ranges",
    29  		"age",
    30  		"access-control-allow-credentials",
    31  		"access-control-allow-headers",
    32  		"access-control-allow-methods",
    33  		"access-control-allow-origin",
    34  		"access-control-expose-headers",
    35  		"access-control-max-age",
    36  		"access-control-request-headers",
    37  		"access-control-request-method",
    38  		"allow",
    39  		"authorization",
    40  		"cache-control",
    41  		"content-disposition",
    42  		"content-encoding",
    43  		"content-language",
    44  		"content-length",
    45  		"content-location",
    46  		"content-range",
    47  		"content-type",
    48  		"cookie",
    49  		"date",
    50  		"etag",
    51  		"expect",
    52  		"expires",
    53  		"from",
    54  		"host",
    55  		"if-match",
    56  		"if-modified-since",
    57  		"if-none-match",
    58  		"if-unmodified-since",
    59  		"last-modified",
    60  		"link",
    61  		"location",
    62  		"max-forwards",
    63  		"origin",
    64  		"proxy-authenticate",
    65  		"proxy-authorization",
    66  		"range",
    67  		"referer",
    68  		"refresh",
    69  		"retry-after",
    70  		"server",
    71  		"set-cookie",
    72  		"strict-transport-security",
    73  		"trailer",
    74  		"transfer-encoding",
    75  		"user-agent",
    76  		"vary",
    77  		"via",
    78  		"www-authenticate",
    79  		"x-forwarded-for",
    80  		"x-forwarded-proto",
    81  	}
    82  	commonLowerHeader = make(map[string]string, len(common))
    83  	commonCanonHeader = make(map[string]string, len(common))
    84  	for _, v := range common {
    85  		chk := http.CanonicalHeaderKey(v)
    86  		commonLowerHeader[chk] = v
    87  		commonCanonHeader[v] = chk
    88  	}
    89  }
    90  
    91  func lowerHeader(v string) (lower string, ascii bool) {
    92  	buildCommonHeaderMapsOnce()
    93  	if s, ok := commonLowerHeader[v]; ok {
    94  		return s, true
    95  	}
    96  	return asciiToLower(v)
    97  }
    98  
    99  func canonicalHeader(v string) string {
   100  	buildCommonHeaderMapsOnce()
   101  	if s, ok := commonCanonHeader[v]; ok {
   102  		return s
   103  	}
   104  	return http.CanonicalHeaderKey(v)
   105  }
   106
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