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<title>[51939] trunk: Admin/HTTP API: add suggested filename support to `download_url()`.</title>
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<dt style="float: left; width: 6em; font-weight: bold">Revision</dt> <dd><a style="font-weight: bold" href="https://core.trac.wordpress.org/changeset/51939">51939</a><script type="application/ld+json">{"@context":"http://schema.org","@type":"EmailMessage","description":"Review this Commit","action":{"@type":"ViewAction","url":"https://core.trac.wordpress.org/changeset/51939","name":"Review Commit"}}</script></dd>
<dt style="float: left; width: 6em; font-weight: bold">Author</dt> <dd>johnjamesjacoby</dd>
<dt style="float: left; width: 6em; font-weight: bold">Date</dt> <dd>2021-10-27 14:58:24 +0000 (Wed, 27 Oct 2021)</dd>
</dl>
<pre style='padding-left: 1em; margin: 2em 0; border-left: 2px solid #ccc; line-height: 1.25; font-size: 105%; font-family: sans-serif'>Admin/HTTP API: add suggested filename support to `download_url()`.
This change allows for external clients to supply a suggested filename via a `Content-Disposition` response header. This filename is processed through `sanitize_file_name()` to ensure it is allowable (on the server, MIME's, etc...) and `validate_file()` to prevent directory traversal.
If the suggested filename fails the above processing/checks, that suggestion is discarded and the standard temporary filename (generated by WordPress) is used.
If no `Content-Disposition` header is found in the response headers, the standard temporary filename continues to be used as per normal.
Included in this change are 6 additional PHPUnit tests with 9 assertions. These tests confirm that valid filename values are correctly saved, and invalid filename values are correctly rejected.
Props cklosows, costdev, dd32, johnjamesjacoby, ocean90, psrpinto.
Fixes <a href="https://core.trac.wordpress.org/ticket/38231">#38231</a>.</pre>
<h3>Modified Paths</h3>
<ul>
<li><a href="#trunksrcwpadminincludesfilephp">trunk/src/wp-admin/includes/file.php</a></li>
<li><a href="#trunktestsphpunittestsadminincludesFilephp">trunk/tests/phpunit/tests/admin/includesFile.php</a></li>
</ul>
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<h3>Diff</h3>
<a id="trunksrcwpadminincludesfilephp"></a>
<div class="modfile"><h4 style="background-color: #eee; color: inherit; margin: 1em 0; padding: 1.3em; font-size: 115%">Modified: trunk/src/wp-admin/includes/file.php</h4>
<pre class="diff"><span>
<span class="info" style="display: block; padding: 0 10px; color: #888">--- trunk/src/wp-admin/includes/file.php 2021-10-26 02:02:50 UTC (rev 51938)
+++ trunk/src/wp-admin/includes/file.php 2021-10-27 14:58:24 UTC (rev 51939)
</span><span class="lines" style="display: block; padding: 0 10px; color: #888">@@ -1112,6 +1112,7 @@
</span><span class="cx" style="display: block; padding: 0 10px"> *
</span><span class="cx" style="display: block; padding: 0 10px"> * @since 2.5.0
</span><span class="cx" style="display: block; padding: 0 10px"> * @since 5.2.0 Signature Verification with SoftFail was added.
</span><ins style="background-color: #dfd; text-decoration:none; display:block; padding: 0 10px">+ * @since 5.9.0 Support for Content-Disposition filename was added.
</ins><span class="cx" style="display: block; padding: 0 10px"> *
</span><span class="cx" style="display: block; padding: 0 10px"> * @param string $url The URL of the file to download.
</span><span class="cx" style="display: block; padding: 0 10px"> * @param int $timeout The timeout for the request to download the file.
</span><span class="lines" style="display: block; padding: 0 10px; color: #888">@@ -1182,6 +1183,29 @@
</span><span class="cx" style="display: block; padding: 0 10px"> return new WP_Error( 'http_404', trim( wp_remote_retrieve_response_message( $response ) ), $data );
</span><span class="cx" style="display: block; padding: 0 10px"> }
</span><span class="cx" style="display: block; padding: 0 10px">
</span><ins style="background-color: #dfd; text-decoration:none; display:block; padding: 0 10px">+ $content_disposition = wp_remote_retrieve_header( $response, 'content-disposition' );
+
+ if ( $content_disposition ) {
+ $content_disposition = strtolower( $content_disposition );
+
+ if ( 0 === strpos( $content_disposition, 'attachment; filename=' ) ) {
+ $tmpfname_disposition = sanitize_file_name( substr( $content_disposition, 21 ) );
+ } else {
+ $tmpfname_disposition = '';
+ }
+
+ // Potential file name must be valid string
+ if ( $tmpfname_disposition && is_string( $tmpfname_disposition ) && ( 0 === validate_file( $tmpfname_disposition ) ) ) {
+ if ( rename( $tmpfname, $tmpfname_disposition ) ) {
+ $tmpfname = $tmpfname_disposition;
+ }
+
+ if ( ( $tmpfname !== $tmpfname_disposition ) && file_exists( $tmpfname_disposition ) ) {
+ unlink( $tmpfname_disposition );
+ }
+ }
+ }
+
</ins><span class="cx" style="display: block; padding: 0 10px"> $content_md5 = wp_remote_retrieve_header( $response, 'content-md5' );
</span><span class="cx" style="display: block; padding: 0 10px">
</span><span class="cx" style="display: block; padding: 0 10px"> if ( $content_md5 ) {
</span></span></pre></div>
<a id="trunktestsphpunittestsadminincludesFilephp"></a>
<div class="modfile"><h4 style="background-color: #eee; color: inherit; margin: 1em 0; padding: 1.3em; font-size: 115%">Modified: trunk/tests/phpunit/tests/admin/includesFile.php</h4>
<pre class="diff"><span>
<span class="info" style="display: block; padding: 0 10px; color: #888">--- trunk/tests/phpunit/tests/admin/includesFile.php 2021-10-26 02:02:50 UTC (rev 51938)
+++ trunk/tests/phpunit/tests/admin/includesFile.php 2021-10-27 14:58:24 UTC (rev 51939)
</span><span class="lines" style="display: block; padding: 0 10px; color: #888">@@ -79,6 +79,177 @@
</span><span class="cx" style="display: block; padding: 0 10px"> }
</span><span class="cx" style="display: block; padding: 0 10px">
</span><span class="cx" style="display: block; padding: 0 10px"> /**
</span><ins style="background-color: #dfd; text-decoration:none; display:block; padding: 0 10px">+ * @ticket 38231
+ * @dataProvider data_download_url_should_respect_filename_from_content_disposition_header
+ *
+ * @covers ::download_url
+ *
+ * @param $filter A callback containing a fake Content-Disposition header.
+ */
+ public function test_download_url_should_respect_filename_from_content_disposition_header( $filter ) {
+ add_filter( 'pre_http_request', array( $this, $filter ), 10, 3 );
+
+ $filename = download_url( 'url_with_content_disposition_header' );
+ $this->assertStringContainsString( 'filename-from-content-disposition-header', $filename );
+ $this->assertFileExists( $filename );
+ $this->unlink( $filename );
+
+ remove_filter( 'pre_http_request', array( $this, $filter ) );
+ }
+
+ /**
+ * Data provider for test_download_url_should_respect_filename_from_content_disposition_header.
+ *
+ * @return array
+ */
+ public function data_download_url_should_respect_filename_from_content_disposition_header() {
+ return array(
+ 'valid parameters' => array( 'filter_content_disposition_header_with_filename' ),
+ 'path traversal' => array( 'filter_content_disposition_header_with_filename_with_path_traversal' ),
+ 'no quotes' => array( 'filter_content_disposition_header_with_filename_without_quotes' ),
+ );
+ }
+
+ /**
+ * Filter callback for data_download_url_should_respect_filename_from_content_disposition_header.
+ *
+ * @since 5.9.0
+ *
+ * @return array
+ */
+ public function filter_content_disposition_header_with_filename( $response, $args, $url ) {
+ return array(
+ 'response' => array(
+ 'code' => 200,
+ ),
+ 'headers' => array(
+ 'content-disposition' => 'attachment; filename="filename-from-content-disposition-header.txt"',
+ ),
+ );
+ }
+
+ /**
+ * Filter callback for data_download_url_should_respect_filename_from_content_disposition_header.
+ *
+ * @since 5.9.0
+ *
+ * @return array
+ */
+ public function filter_content_disposition_header_with_filename_with_path_traversal( $response, $args, $url ) {
+ return array(
+ 'response' => array(
+ 'code' => 200,
+ ),
+ 'headers' => array(
+ 'content-disposition' => 'attachment; filename="../../filename-from-content-disposition-header.txt"',
+ ),
+ );
+ }
+
+ /**
+ * Filter callback for data_download_url_should_respect_filename_from_content_disposition_header.
+ *
+ * @since 5.9.0
+ *
+ * @return array
+ */
+ public function filter_content_disposition_header_with_filename_without_quotes( $response, $args, $url ) {
+ return array(
+ 'response' => array(
+ 'code' => 200,
+ ),
+ 'headers' => array(
+ 'content-disposition' => 'attachment; filename=filename-from-content-disposition-header.txt',
+ ),
+ );
+ }
+
+ /**
+ * @ticket 38231
+ * @dataProvider data_download_url_should_reject_filename_from_invalid_content_disposition_header
+ *
+ * @covers ::download_url
+ *
+ * @param $filter A callback containing a fake Content-Disposition header.
+ */
+ public function test_download_url_should_reject_filename_from_invalid_content_disposition_header( $filter ) {
+ add_filter( 'pre_http_request', array( $this, $filter ), 10, 3 );
+
+ $filename = download_url( 'url_with_content_disposition_header' );
+ $this->assertStringContainsString( 'url_with_content_disposition_header', $filename );
+ $this->unlink( $filename );
+
+ remove_filter( 'pre_http_request', array( $this, $filter ) );
+ }
+
+ /**
+ * Data provider for test_download_url_should_reject_filename_from_invalid_content_disposition_header.
+ *
+ * @return array
+ */
+ public function data_download_url_should_reject_filename_from_invalid_content_disposition_header() {
+ return array(
+ 'no context' => array( 'filter_content_disposition_header_with_filename_without_context' ),
+ 'inline context' => array( 'filter_content_disposition_header_with_filename_with_inline_context' ),
+ 'form-data context' => array( 'filter_content_disposition_header_with_filename_with_form_data_context' ),
+ );
+ }
+
+ /**
+ * Filter callback for data_download_url_should_reject_filename_from_invalid_content_disposition_header.
+ *
+ * @since 5.9.0
+ *
+ * @return array
+ */
+ public function filter_content_disposition_header_with_filename_without_context( $response, $args, $url ) {
+ return array(
+ 'response' => array(
+ 'code' => 200,
+ ),
+ 'headers' => array(
+ 'content-disposition' => 'filename="filename-from-content-disposition-header.txt"',
+ ),
+ );
+ }
+
+ /**
+ * Filter callback for data_download_url_should_reject_filename_from_invalid_content_disposition_header.
+ *
+ * @since 5.9.0
+ *
+ * @return array
+ */
+ public function filter_content_disposition_header_with_filename_with_inline_context( $response, $args, $url ) {
+ return array(
+ 'response' => array(
+ 'code' => 200,
+ ),
+ 'headers' => array(
+ 'content-disposition' => 'inline; filename="filename-from-content-disposition-header.txt"',
+ ),
+ );
+ }
+
+ /**
+ * Filter callback for data_download_url_should_reject_filename_from_invalid_content_disposition_header.
+ *
+ * @since 5.9.0
+ *
+ * @return array
+ */
+ public function filter_content_disposition_header_with_filename_with_form_data_context( $response, $args, $url ) {
+ return array(
+ 'response' => array(
+ 'code' => 200,
+ ),
+ 'headers' => array(
+ 'content-disposition' => 'form-data; name="file"; filename="filename-from-content-disposition-header.txt"',
+ ),
+ );
+ }
+
+ /**
</ins><span class="cx" style="display: block; padding: 0 10px"> * Verify that a WP_Error object is returned when invalid input is passed as the `$url` parameter.
</span><span class="cx" style="display: block; padding: 0 10px"> *
</span><span class="cx" style="display: block; padding: 0 10px"> * @covers ::download_url
</span></span></pre>
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