Changeset 55667

Timestamp:

04/20/2023 05:08:47 PM (3 years ago)

Author:

Bernhard Reiter

Message:

HTML API: Add support for a few invalid HTML comment forms.

• Comments created by means of a tag closer with an invalid tag name, e.g. </3>.
• Comments closed with the invalid --!> closer. (Comments should be closed by --> but if the ! appears it will also close it, in error.)
• Empty tag name elements, which are technically skipped over and aren't comments, e.g. </>.

Props dmsnell, costdev.
Fixes #58007.

Location:

trunk

Files:

• src/wp-includes/html-api/class-wp-html-tag-processor.php (modified) (3 diffs)
• tests/phpunit/tests/html-api/wpHtmlTagProcessor.php (modified) (2 diffs)

trunk/src/wp-includes/html-api/class-wp-html-tag-processor.php

@@ -972 +972 @@
          *
          * @since 6.2.0
+         * @since 6.2.1 Support abruptly-closed comments, invalid-tag-closer-comments, and empty elements.
          *
          * @return bool Whether a tag was found before the end of the document.
@@ -1040 +1041 @@
                                         '-' === $html[ $at + 3 ]
                                 ) {
-                                        $closer_at = strpos( $html, '-->', $at + 4 );
-                                        if ( false === $closer_at ) {
+                                        $closer_at = $at + 4;
+                                        // If it's not possible to close the comment then there is nothing more to scan.
+                                        if ( strlen( $html ) <= $closer_at ) {
                                                 return false;
                                         }
 
-                                        $at = $closer_at + 3;
-                                        continue;
+                                        // Abruptly-closed empty comments are a sequence of dashes followed by `>`.
+                                        $span_of_dashes = strspn( $html, '-', $closer_at );
+                                        if ( '>' === $html[ $closer_at + $span_of_dashes ] ) {
+                                                $at = $closer_at + $span_of_dashes + 1;
+                                                continue;
+                                        }
+
+                                        /*
+                                         * Comments may be closed by either a --> or an invalid --!>.
+                                         * The first occurrence closes the comment.
+                                         *
+                                         * See https://html.spec.whatwg.org/#parse-error-incorrectly-closed-comment
+                                         */
+                                        $closer_at--; // Pre-increment inside condition below reduces risk of accidental infinite looping.
+                                        while ( ++$closer_at < strlen( $html ) ) {
+                                                $closer_at = strpos( $html, '--', $closer_at );
+                                                if ( false === $closer_at ) {
+                                                        return false;
+                                                }
+
+                                                if ( $closer_at + 2 < strlen( $html ) && '>' === $html[ $closer_at + 2 ] ) {
+                                                        $at = $closer_at + 3;
+                                                        continue 2;
+                                                }
+
+                                                if ( $closer_at + 3 < strlen( $html ) && '!' === $html[ $closer_at + 2 ] && '>' === $html[ $closer_at + 3 ] ) {
+                                                        $at = $closer_at + 4;
+                                                        continue 2;
+                                                }
+                                        }
                                 }
 
@@ -1106 +1136 @@
 
                         /*
+                         * </> is a missing end tag name, which is ignored.
+                         *
+                         * See https://html.spec.whatwg.org/#parse-error-missing-end-tag-name
+                         */
+                        if ( '>' === $html[ $at + 1 ] ) {
+                                $at++;
+                                continue;
+                        }
+
+                        /*
                          * <? transitions to a bogus comment state – skip to the nearest >
-                         * https://html.spec.whatwg.org/multipage/parsing.html#tag-open-state
+                         * See https://html.spec.whatwg.org/multipage/parsing.html#tag-open-state
                          */
                         if ( '?' === $html[ $at + 1 ] ) {
                                 $closer_at = strpos( $html, '>', $at + 2 );
+                                if ( false === $closer_at ) {
+                                        return false;
+                                }
+
+                                $at = $closer_at + 1;
+                                continue;
+                        }
+
+                        /*
+                         * If a non-alpha starts the tag name in a tag closer it's a comment.
+                         * Find the first `>`, which closes the comment.
+                         *
+                         * See https://html.spec.whatwg.org/#parse-error-invalid-first-character-of-tag-name
+                         */
+                        if ( $this->is_closing_tag ) {
+                                $closer_at = strpos( $html, '>', $at + 3 );
                                 if ( false === $closer_at ) {
                                         return false;

trunk/tests/phpunit/tests/html-api/wpHtmlTagProcessor.php

@@ -1734 +1734 @@
 
         /**
+         * Invalid tag names are comments on tag closers.
+         *
+         * @ticket 58007
+         *
+         * @link https://html.spec.whatwg.org/#parse-error-invalid-first-character-of-tag-name
+         *
+         * @dataProvider data_next_tag_ignores_invalid_first_character_of_tag_name_comments
+         *
+         * @param string $html_with_markers HTML containing an invalid tag closer whose element before and
+         *                                  element after contain the "start" and "end" CSS classes.
+         */
+        public function test_next_tag_ignores_invalid_first_character_of_tag_name_comments( $html_with_markers ) {
+                $p = new WP_HTML_Tag_Processor( $html_with_markers );
+                $p->next_tag( array( 'class_name' => 'start' ) );
+                $p->next_tag();
+
+                $this->assertSame( 'end', $p->get_attribute( 'class' ) );
+        }
+
+        /**
+         * Data provider.
+         *
+         * @return array[]
+         */
+        public function data_next_tag_ignores_invalid_first_character_of_tag_name_comments() {
+                return array(
+                        'Invalid tag openers as normal text'           => array(
+                                '<ul><li><div class=start>I <3 when outflow > inflow</div><img class=end></li></ul>',
+                        ),
+
+                        'Invalid tag closers as comments'              => array(
+                                '<ul><li><div class=start>I </3 when <img> outflow <br class=end> inflow</div></li></ul>',
+                        ),
+
+                        'Unexpected question mark instead of tag name' => array(
+                                '<div class=start><?xml-stylesheet type="text/css" href="style.css"?><hr class=end>',
+                        ),
+                );
+        }
+
+        /**
          * @ticket 56299
          *
@@ -1782 +1823 @@
                                 'rcdata_tag'      => 'TEXTAREA',
                         ),
+                );
+        }
+
+        /**
+         * Ensures that the invalid comment closing syntax "--!>" properly closes a comment.
+         *
+         * @ticket 58007
+         *
+         * @covers WP_HTML_Tag_Processor::next_tag
+         *
+         */
+        public function test_allows_incorrectly_closed_comments() {
+                $p = new WP_HTML_Tag_Processor( '<img id=before><!-- <img id=inside> --!><img id=after>--><img id=final>' );
+
+                $p->next_tag();
+                $this->assertSame( 'before', $p->get_attribute( 'id' ), 'Did not find starting tag.' );
+
+                $p->next_tag();
+                $this->assertSame( 'after', $p->get_attribute( 'id' ), 'Did not properly close improperly-closed comment.' );
+
+                $p->next_tag();
+                $this->assertSame( 'final', $p->get_attribute( 'id' ), 'Did not skip over unopened comment-closer.' );
+        }
+
+        /**
+         * Ensures that unclosed and invalid comments don't trigger warnings or errors.
+         *
+         * @ticket 58007
+         *
+         * @covers WP_HTML_Tag_Processor::next_tag
+         *
+         * @dataProvider data_html_with_unclosed_comments
+         *
+         * @param string $html_ending_before_comment_close HTML with opened comments that aren't closed
+         */
+        public function test_documents_may_end_with_unclosed_comment( $html_ending_before_comment_close ) {
+                $p = new WP_HTML_Tag_Processor( $html_ending_before_comment_close );
+
+                $this->assertFalse( $p->next_tag() );
+        }
+
+        /**
+         * Data provider.
+         *
+         * @return array[]
+         */
+        public function data_html_with_unclosed_comments() {
+                return array(
+                        'Shortest open valid comment'      => array( '<!--' ),
+                        'Basic truncated comment'          => array( '<!-- this ends --' ),
+                        'Comment with closer look-alike'   => array( '<!-- this ends --x' ),
+                        'Comment with closer look-alike 2' => array( '<!-- this ends --!x' ),
+                        'Invalid tag-closer comment'       => array( '</(when will this madness end?)' ),
+                        'Invalid tag-closer comment 2'     => array( '</(when will this madness end?)--' ),
+                );
+        }
+
+        /**
+         * Ensures that abruptly-closed empty comments are properly closed.
+         *
+         * @ticket 58007
+         *
+         * @covers WP_HTML_Tag_Processor::next_tag
+         *
+         * @dataProvider data_abruptly_closed_empty_comments
+         *
+         * @param string $html_with_after_marker HTML to test with "id=after" on element immediately following an abruptly closed comment.
+         */
+        public function test_closes_abrupt_closing_of_empty_comment( $html_with_after_marker ) {
+                $p = new WP_HTML_Tag_Processor( $html_with_after_marker );
+                $p->next_tag();
+                $p->next_tag();
+
+                $this->assertSame( 'after', $p->get_attribute( 'id' ), 'Did not find tag after closing abruptly-closed comment' );
+        }
+
+        /**
+         * Data provider.
+         *
+         * @return array[]
+         */
+        public function data_abruptly_closed_empty_comments() {
+                return array(
+                        'Empty comment with two dashes only' => array( '<hr><!--><hr id=after>' ),
+                        'Empty comment with two dashes only, improperly closed' => array( '<hr><!--!><hr id=inside>--><hr id=after>' ),
+                        'Comment with two dashes only, improperly closed twice' => array( '<hr><!--!><hr id=inside>--!><hr id=after>' ),
+                        'Empty comment with three dashes'    => array( '<hr><!---><hr id=after>' ),
+                        'Empty comment with three dashes, improperly closed' => array( '<hr><!---!><hr id=inside>--><hr id=after>' ),
+                        'Comment with three dashes, improperly closed twice' => array( '<hr><!---!><hr id=inside>--!><hr id=after>' ),
+                        'Empty comment with four dashes'     => array( '<hr><!----><hr id=after>' ),
+                        'Empty comment with four dashes, improperly closed' => array( '<hr><!----!><hr id=after>--><hr id=final>' ),
+                        'Comment with four dashes, improperly closed twice' => array( '<hr><!----!><hr id=after>--!><hr id=final>' ),
+                        'Comment with almost-closer inside'  => array( '<hr><!-- ---!><hr id=after>--!><hr id=final>' ),
                 );
         }