1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
|
<?php
namespace MediaWiki\Rest;
use MediaWiki\Rest\HeaderParser\HttpDate;
use MediaWiki\Rest\HeaderParser\IfNoneMatch;
use RuntimeException;
use Wikimedia\Timestamp\ConvertibleTimestamp;
class ConditionalHeaderUtil {
/** @var bool */
private $varnishETagHack = true;
/** @var string|null */
private $eTag;
/** @var int|null */
private $lastModified;
/** @var bool */
private $hasRepresentation;
/**
* Initialize the object with information about the requested resource.
*
* @param string|null $eTag The entity-tag (including quotes), or null if
* it is unknown.
* @param string|int|null $lastModified The Last-Modified date in a format
* accepted by ConvertibleTimestamp, or null if it is unknown.
* @param bool|null $hasRepresentation Whether the server has a current
* representation of the target resource. This should be true if the
* resource exists, and false if it does not exist. It is used for
* wildcard validators -- the intended use case is to abort a PUT if the
* resource does (or does not) exist. If null is passed, we assume that
* the resource exists if an ETag was specified for it.
*/
public function setValidators( $eTag, $lastModified, $hasRepresentation ) {
$this->eTag = $eTag;
if ( $lastModified === null ) {
$this->lastModified = null;
} else {
$this->lastModified = (int)ConvertibleTimestamp::convert( TS_UNIX, $lastModified );
}
$this->hasRepresentation = $hasRepresentation ?? ( $eTag !== null );
}
/**
* If the Varnish ETag hack is disabled by calling this method,
* strong ETag comparison will follow RFC 7232, rejecting all weak
* ETags for If-Match comparison.
*
* @param bool $hack
*/
public function setVarnishETagHack( $hack ) {
$this->varnishETagHack = $hack;
}
/**
* Check conditional request headers in the order required by RFC 7232 section 6.
*
* @param RequestInterface $request
* @return int|null The status code to immediately return, or null to
* continue processing the request.
*/
public function checkPreconditions( RequestInterface $request ) {
$parser = new IfNoneMatch;
if ( $this->eTag !== null ) {
$resourceTag = $parser->parseETag( $this->eTag );
if ( !$resourceTag ) {
throw new RuntimeException( 'Invalid ETag returned by handler: `' .
$parser->getLastError() . '`' );
}
} else {
$resourceTag = null;
}
$getOrHead = in_array( $request->getMethod(), [ 'GET', 'HEAD' ] );
if ( $request->hasHeader( 'If-Match' ) ) {
$im = $request->getHeader( 'If-Match' );
$match = false;
foreach ( $parser->parseHeaderList( $im ) as $tag ) {
if ( ( $tag['whole'] === '*' && $this->hasRepresentation ) ||
$this->strongCompare( $resourceTag, $tag )
) {
$match = true;
break;
}
}
if ( !$match ) {
return 412;
}
} elseif ( $request->hasHeader( 'If-Unmodified-Since' ) ) {
$requestDate = HttpDate::parse( $request->getHeader( 'If-Unmodified-Since' )[0] );
if ( $requestDate !== null
&& ( $this->lastModified === null || $this->lastModified > $requestDate )
) {
return 412;
}
}
if ( $request->hasHeader( 'If-None-Match' ) ) {
$inm = $request->getHeader( 'If-None-Match' );
foreach ( $parser->parseHeaderList( $inm ) as $tag ) {
if ( ( $tag['whole'] === '*' && $this->hasRepresentation ) ||
$this->weakCompare( $resourceTag, $tag )
) {
return $getOrHead ? 304 : 412;
}
}
} elseif ( $getOrHead && $request->hasHeader( 'If-Modified-Since' ) ) {
$requestDate = HttpDate::parse( $request->getHeader( 'If-Modified-Since' )[0] );
if ( $requestDate !== null && $this->lastModified !== null
&& $this->lastModified <= $requestDate
) {
return 304;
}
}
// RFC 7232 states that If-Range should be evaluated here. However, the
// purpose of If-Range is to cause the Range request header to be
// conditionally ignored, not to immediately send a response, so it
// doesn't fit here. RFC 7232 only requires that If-Range be checked
// after the other conditional header fields, a requirement that is
// satisfied if it is processed in Handler::execute().
return null;
}
/**
* Set Last-Modified and ETag headers in the response according to the cached
* values set by setValidators(), which are also used for precondition checks.
*
* If the headers are already present in the response, the existing headers
* take precedence.
*
* @param ResponseInterface $response
*/
public function applyResponseHeaders( ResponseInterface $response ) {
if ( $this->lastModified !== null && !$response->hasHeader( 'Last-Modified' ) ) {
$response->setHeader( 'Last-Modified', HttpDate::format( $this->lastModified ) );
}
if ( $this->eTag !== null && !$response->hasHeader( 'ETag' ) ) {
$response->setHeader( 'ETag', $this->eTag );
}
}
/**
* The weak comparison function, per RFC 7232, section 2.3.2.
*
* @param array|null $resourceETag ETag generated by the handler, parsed tag info array
* @param array|null $headerETag ETag supplied by the client, parsed tag info array
* @return bool
*/
private function weakCompare( $resourceETag, $headerETag ) {
if ( $resourceETag === null || $headerETag === null ) {
return false;
}
return $resourceETag['contents'] === $headerETag['contents'];
}
/**
* The strong comparison function
*
* A strong ETag returned by the server may have been "weakened" by Varnish when applying
* compression. So optionally ignore the weakness of the header.
* {@link https://varnish-cache.org/docs/6.0/users-guide/compression.html}.
* @see T238849 and T310710
*
* @param array|null $resourceETag ETag generated by the handler, parsed tag info array
* @param array|null $headerETag ETag supplied by the client, parsed tag info array
*
* @return bool
*/
private function strongCompare( $resourceETag, $headerETag ) {
if ( $resourceETag === null || $headerETag === null ) {
return false;
}
return !$resourceETag['weak']
&& ( $this->varnishETagHack || !$headerETag['weak'] )
&& $resourceETag['contents'] === $headerETag['contents'];
}
}
|
