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| 1 | <?php |
| 2 | |
| 3 | namespace MediaWiki\Rest; |
| 4 | |
| 5 | use MediaWiki\Config\ServiceOptions; |
| 6 | use MediaWiki\MainConfigNames; |
| 7 | use MediaWiki\Rest\BasicAccess\BasicAuthorizerInterface; |
| 8 | use MediaWiki\Rest\HeaderParser\Origin; |
| 9 | use MediaWiki\User\UserIdentity; |
| 10 | |
| 11 | /** |
| 12 | * @internal |
| 13 | */ |
| 14 | class CorsUtils implements BasicAuthorizerInterface { |
| 15 | /** @var array */ |
| 16 | public const CONSTRUCTOR_OPTIONS = [ |
| 17 | MainConfigNames::AllowedCorsHeaders, |
| 18 | MainConfigNames::AllowCrossOrigin, |
| 19 | MainConfigNames::RestAllowCrossOriginCookieAuth, |
| 20 | MainConfigNames::CanonicalServer, |
| 21 | MainConfigNames::CrossSiteAJAXdomains, |
| 22 | MainConfigNames::CrossSiteAJAXdomainExceptions, |
| 23 | ]; |
| 24 | |
| 25 | /** @var ServiceOptions */ |
| 26 | private $options; |
| 27 | |
| 28 | /** @var ResponseFactory */ |
| 29 | private $responseFactory; |
| 30 | |
| 31 | /** @var UserIdentity */ |
| 32 | private $user; |
| 33 | |
| 34 | /** |
| 35 | * @param ServiceOptions $options |
| 36 | * @param ResponseFactory $responseFactory |
| 37 | * @param UserIdentity $user |
| 38 | */ |
| 39 | public function __construct( |
| 40 | ServiceOptions $options, |
| 41 | ResponseFactory $responseFactory, |
| 42 | UserIdentity $user |
| 43 | ) { |
| 44 | $options->assertRequiredOptions( self::CONSTRUCTOR_OPTIONS ); |
| 45 | $this->options = $options; |
| 46 | $this->responseFactory = $responseFactory; |
| 47 | $this->user = $user; |
| 48 | } |
| 49 | |
| 50 | /** |
| 51 | * Only allow registered users to make unsafe cross-origin requests. |
| 52 | * |
| 53 | * @param RequestInterface $request |
| 54 | * @param Handler $handler |
| 55 | * @return string|null If the request is denied, the string error code. If |
| 56 | * the request is allowed, null. |
| 57 | */ |
| 58 | public function authorize( RequestInterface $request, Handler $handler ) { |
| 59 | // Handlers that need write access are by definition a cache-miss, therefore there is no |
| 60 | // need to vary by the origin. |
| 61 | if ( |
| 62 | $handler->needsWriteAccess() |
| 63 | && $request->hasHeader( 'Origin' ) |
| 64 | && !$this->user->isRegistered() |
| 65 | ) { |
| 66 | $origin = Origin::parseHeaderList( $request->getHeader( 'Origin' ) ); |
| 67 | |
| 68 | if ( !$this->allowOrigin( $origin ) ) { |
| 69 | return 'rest-cross-origin-anon-write'; |
| 70 | } |
| 71 | } |
| 72 | |
| 73 | return null; |
| 74 | } |
| 75 | |
| 76 | /** |
| 77 | * @param Origin $origin |
| 78 | * @return bool |
| 79 | */ |
| 80 | private function allowOrigin( Origin $origin ): bool { |
| 81 | $allowed = array_merge( [ $this->getCanonicalDomain() ], |
| 82 | $this->options->get( MainConfigNames::CrossSiteAJAXdomains ) ); |
| 83 | $excluded = $this->options->get( MainConfigNames::CrossSiteAJAXdomainExceptions ); |
| 84 | |
| 85 | return $origin->match( $allowed, $excluded ); |
| 86 | } |
| 87 | |
| 88 | /** |
| 89 | * @return string |
| 90 | */ |
| 91 | private function getCanonicalDomain(): string { |
| 92 | $res = parse_url( $this->options->get( MainConfigNames::CanonicalServer ) ); |
| 93 | '@phan-var array $res'; |
| 94 | |
| 95 | $host = $res['host'] ?? ''; |
| 96 | $port = $res['port'] ?? null; |
| 97 | |
| 98 | return $port ? "$host:$port" : $host; |
| 99 | } |
| 100 | |
| 101 | /** |
| 102 | * Modify response to allow for CORS. |
| 103 | * |
| 104 | * This method should be executed for every response from the REST API |
| 105 | * including errors. |
| 106 | * |
| 107 | * @param RequestInterface $request |
| 108 | * @param ResponseInterface $response |
| 109 | * @return ResponseInterface |
| 110 | */ |
| 111 | public function modifyResponse( RequestInterface $request, ResponseInterface $response ): ResponseInterface { |
| 112 | if ( !$this->options->get( MainConfigNames::AllowCrossOrigin ) ) { |
| 113 | return $response; |
| 114 | } |
| 115 | |
| 116 | $allowedOrigin = '*'; |
| 117 | |
| 118 | if ( $this->options->get( MainConfigNames::RestAllowCrossOriginCookieAuth ) ) { |
| 119 | // @TODO Since we only Vary the response if (1) the method is OPTIONS or (2) the user is |
| 120 | // registered, it is safe to only add the Vary: Origin when those two conditions |
| 121 | // are met since a response to a logged-in user's request is not cachable. |
| 122 | // Therefore, logged out users should always get `Access-Control-Allow-Origin: *` |
| 123 | // on all non-OPTIONS request and logged-in users *may* get |
| 124 | // `Access-Control-Allow-Origin: <requested origin>` |
| 125 | |
| 126 | // Vary All Requests by the Origin header. |
| 127 | $response->addHeader( 'Vary', 'Origin' ); |
| 128 | |
| 129 | // If the Origin header is missing, there is nothing to check against. |
| 130 | if ( $request->hasHeader( 'Origin' ) ) { |
| 131 | $origin = Origin::parseHeaderList( $request->getHeader( 'Origin' ) ); |
| 132 | if ( $this->allowOrigin( $origin ) ) { |
| 133 | // Only set the allowed origin for preflight requests, or for main requests where a registered |
| 134 | // user is authenticated. This prevents having to Vary all requests by the Origin. |
| 135 | // Anonymous users will always get '*', registered users *may* get the requested origin back. |
| 136 | if ( $request->getMethod() === 'OPTIONS' || $this->user->isRegistered() ) { |
| 137 | $allowedOrigin = $origin->getSingleOrigin(); |
| 138 | } |
| 139 | } |
| 140 | } |
| 141 | } |
| 142 | |
| 143 | // If the Origin was determined to be something other than *any* allow the session |
| 144 | // cookies to be sent with the main request. If this is the main request, allow the |
| 145 | // response to be read. |
| 146 | // |
| 147 | // If the client includes the credentials on a simple request (HEAD, GET, etc.), but |
| 148 | // they do not pass this check, the browser will refuse to allow the client to read the |
| 149 | // response. The client may resolve this by repeating the request without the |
| 150 | // credentials. |
| 151 | if ( $allowedOrigin !== '*' ) { |
| 152 | $response->setHeader( 'Access-Control-Allow-Credentials', 'true' ); |
| 153 | } |
| 154 | |
| 155 | $response->setHeader( 'Access-Control-Allow-Origin', $allowedOrigin ); |
| 156 | |
| 157 | return $response; |
| 158 | } |
| 159 | |
| 160 | /** |
| 161 | * Create a CORS preflight response. |
| 162 | * |
| 163 | * @param array $allowedMethods |
| 164 | * @return ResponseInterface |
| 165 | */ |
| 166 | public function createPreflightResponse( array $allowedMethods ): ResponseInterface { |
| 167 | $response = $this->responseFactory->createNoContent(); |
| 168 | $response->setHeader( 'Access-Control-Allow-Methods', $allowedMethods ); |
| 169 | |
| 170 | $allowedHeaders = $this->options->get( MainConfigNames::AllowedCorsHeaders ); |
| 171 | $allowedHeaders = array_merge( $allowedHeaders, array_diff( [ |
| 172 | // Authorization header must be explicitly listed which prevent the use of '*' |
| 173 | 'Authorization', |
| 174 | // REST must allow Content-Type to be operational |
| 175 | 'Content-Type', |
| 176 | // REST relies on conditional requests for some endpoints |
| 177 | 'If-Mach', |
| 178 | 'If-None-Match', |
| 179 | 'If-Modified-Since', |
| 180 | ], $allowedHeaders ) ); |
| 181 | $response->setHeader( 'Access-Control-Allow-Headers', $allowedHeaders ); |
| 182 | |
| 183 | return $response; |
| 184 | } |
| 185 | } |