MediaWiki  master
ConditionalHeaderUtil.php
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1 <?php
2 
3 namespace MediaWiki\Rest;
4 
7 use Wikimedia\Timestamp\ConvertibleTimestamp;
8 
10  private $varnishETagHack = true;
11  private $eTag;
12  private $lastModified;
13  private $hasRepresentation;
14 
29  public function setValidators( $eTag, $lastModified, $hasRepresentation ) {
30  $this->eTag = $eTag;
31  if ( $lastModified === null ) {
32  $this->lastModified = null;
33  } else {
34  $this->lastModified = (int)ConvertibleTimestamp::convert( TS_UNIX, $lastModified );
35  }
36  $this->hasRepresentation = $hasRepresentation ?? ( $eTag !== null );
37  }
38 
46  public function setVarnishETagHack( $hack ) {
47  $this->varnishETagHack = $hack;
48  }
49 
57  public function checkPreconditions( RequestInterface $request ) {
58  $parser = new IfNoneMatch;
59  if ( $this->eTag !== null ) {
60  $resourceTag = $parser->parseETag( $this->eTag );
61  if ( !$resourceTag ) {
62  throw new \Exception( 'Invalid ETag returned by handler: ' .
63  $parser->getLastError() );
64  }
65  } else {
66  $resourceTag = null;
67  }
68  $getOrHead = in_array( $request->getMethod(), [ 'GET', 'HEAD' ] );
69  if ( $request->hasHeader( 'If-Match' ) ) {
70  $im = $request->getHeader( 'If-Match' );
71  $match = false;
72  foreach ( $parser->parseHeaderList( $im ) as $tag ) {
73  if ( $tag['whole'] === '*' && $this->hasRepresentation ) {
74  $match = true;
75  break;
76  }
77 
78  if ( $this->strongCompare( $resourceTag, $tag ) ) {
79  $match = true;
80  break;
81  }
82  }
83  if ( !$match ) {
84  return 412;
85  }
86  } elseif ( $request->hasHeader( 'If-Unmodified-Since' ) ) {
87  $requestDate = HttpDate::parse( $request->getHeader( 'If-Unmodified-Since' )[0] );
88  if ( $requestDate !== null
89  && ( $this->lastModified === null || $this->lastModified > $requestDate )
90  ) {
91  return 412;
92  }
93  }
94  if ( $request->hasHeader( 'If-None-Match' ) ) {
95  $inm = $request->getHeader( 'If-None-Match' );
96  foreach ( $parser->parseHeaderList( $inm ) as $tag ) {
97  if ( $tag['whole'] === '*' && $this->hasRepresentation ) {
98  return $getOrHead ? 304 : 412;
99  }
100  if ( $this->weakCompare( $resourceTag, $tag ) ) {
101  if ( $getOrHead ) {
102  return 304;
103  } else {
104  return 412;
105  }
106  }
107  }
108  } elseif ( $getOrHead && $request->hasHeader( 'If-Modified-Since' ) ) {
109  $requestDate = HttpDate::parse( $request->getHeader( 'If-Modified-Since' )[0] );
110  if ( $requestDate !== null && $this->lastModified !== null
111  && $this->lastModified <= $requestDate
112  ) {
113  return 304;
114  }
115  }
116  // RFC 7232 states that If-Range should be evaluated here. However, the
117  // purpose of If-Range is to cause the Range request header to be
118  // conditionally ignored, not to immediately send a response, so it
119  // doesn't fit here. RFC 7232 only requires that If-Range be checked
120  // after the other conditional header fields, a requirement that is
121  // satisfied if it is processed in Handler::execute().
122  return null;
123  }
124 
134  public function applyResponseHeaders( ResponseInterface $response ) {
135  if ( $this->lastModified !== null && !$response->hasHeader( 'Last-Modified' ) ) {
136  $response->setHeader( 'Last-Modified', HttpDate::format( $this->lastModified ) );
137  }
138  if ( $this->eTag !== null && !$response->hasHeader( 'ETag' ) ) {
139  $response->setHeader( 'ETag', $this->eTag );
140  }
141  }
142 
150  private function weakCompare( $resourceETag, $headerETag ) {
151  if ( $resourceETag === null || $headerETag === null ) {
152  return false;
153  }
154  return $resourceETag['contents'] === $headerETag['contents'];
155  }
156 
170  private function strongCompare( $resourceETag, $headerETag ) {
171  if ( $resourceETag === null || $headerETag === null ) {
172  return false;
173  }
174 
175  return !$resourceETag['weak']
176  && ( $this->varnishETagHack || !$headerETag['weak'] )
177  && $resourceETag['contents'] === $headerETag['contents'];
178  }
179 
180 }
setVarnishETagHack( $hack)
If the Varnish ETag hack is disabled by calling this method, strong ETag comparison will follow RFC 7...
setValidators( $eTag, $lastModified, $hasRepresentation)
Initialize the object with information about the requested resource.
checkPreconditions(RequestInterface $request)
Check conditional request headers in the order required by RFC 7232 section 6.
applyResponseHeaders(ResponseInterface $response)
Set Last-Modified and ETag headers in the response according to the cached values set by setValidator...
This is a parser for "HTTP-date" as defined by RFC 7231.
Definition: HttpDate.php:23
static parse( $dateString)
Parse an HTTP-date string.
Definition: HttpDate.php:80
static format( $unixTime)
A convenience function to convert a UNIX timestamp to the preferred IMF-fixdate format for HTTP heade...
Definition: HttpDate.php:96
A class to assist with the parsing of If-None-Match, If-Match and ETag headers.
Definition: IfNoneMatch.php:8
parseETag( $eTag)
Parse an entity-tag such as might be found in an ETag response header.
Definition: IfNoneMatch.php:68
A request interface similar to PSR-7's ServerRequestInterface.
getMethod()
Retrieves the HTTP method of the request.
hasHeader( $name)
Checks if a header exists by the given case-insensitive name.
getHeader( $name)
Retrieves a message header value by the given case-insensitive name.
An interface similar to PSR-7's ResponseInterface, the primary difference being that it is mutable.
setHeader( $name, $value)
Set or replace the specified header.
hasHeader( $name)
Checks if a header exists by the given case-insensitive name.