Chris@0: <?php
Chris@0: 
Chris@0: namespace Drupal\Component\Render;
Chris@0: 
Chris@0: use Drupal\Component\Utility\Html;
Chris@0: use Drupal\Component\Utility\UrlHelper;
Chris@0: 
Chris@0: /**
Chris@0:  * Formats a string for HTML display by replacing variable placeholders.
Chris@0:  *
Chris@0:  * When cast to a string, this object replaces variable placeholders in the
Chris@0:  * string with the arguments passed in during construction and escapes the
Chris@0:  * values so they can be safely displayed as HTML. See the documentation of
Chris@0:  * \Drupal\Component\Render\FormattableMarkup::placeholderFormat() for details
Chris@0:  * on the supported placeholders and how to use them securely. Incorrect use of
Chris@0:  * this class can result in security vulnerabilities.
Chris@0:  *
Chris@0:  * In most cases, you should use TranslatableMarkup or PluralTranslatableMarkup
Chris@0:  * rather than this object, since they will translate the text (on
Chris@0:  * non-English-only sites) in addition to formatting it. Variables concatenated
Chris@0:  * without the insertion of language-specific words or punctuation are some
Chris@0:  * examples where translation is not applicable and using this class directly
Chris@0:  * directly is appropriate.
Chris@0:  *
Chris@0:  * This class is designed for formatting messages that are mostly text, not as
Chris@0:  * an HTML template language. As such:
Chris@0:  * - The passed in string should contain no (or minimal) HTML.
Chris@0:  * - Variable placeholders should not be used within the "<" and ">" of an
Chris@0:  *   HTML tag, such as in HTML attribute values. This would be a security
Chris@0:  *   risk. Examples:
Chris@0:  *   @code
Chris@0:  *     // Insecure (placeholder within "<" and ">"):
Chris@0:  *     $this->placeholderFormat('<@variable>text</@variable>', ['@variable' => $variable]);
Chris@0:  *     // Insecure (placeholder within "<" and ">"):
Chris@0:  *     $this->placeholderFormat('<a @variable>link text</a>', ['@variable' => $variable]);
Chris@0:  *     // Insecure (placeholder within "<" and ">"):
Chris@0:  *     $this->placeholderFormat('<a title="@variable">link text</a>', ['@variable' => $variable]);
Chris@0:  *   @endcode
Chris@0:  *   Only the "href" attribute is supported via the special ":variable"
Chris@0:  *   placeholder, to allow simple links to be inserted:
Chris@0:  *   @code
Chris@0:  *     // Secure (usage of ":variable" placeholder for href attribute):
Chris@0:  *     $this->placeholderFormat('<a href=":variable">link text</a>', [':variable' , $variable]);
Chris@0:  *     // Secure (usage of ":variable" placeholder for href attribute):
Chris@0:  *     $this->placeholderFormat('<a href=":variable" title="static text">link text</a>', [':variable' => $variable]);
Chris@0:  *     // Insecure (the "@variable" placeholder does not filter dangerous
Chris@0:  *     // protocols):
Chris@0:  *     $this->placeholderFormat('<a href="@variable">link text</a>', ['@variable' => $variable]);
Chris@0:  *     // Insecure ("@variable" placeholder within "<" and ">"):
Chris@0:  *     $this->placeholderFormat('<a href=":url" title="@variable">link text</a>', [':url' => $url, '@variable' => $variable]);
Chris@0:  *   @endcode
Chris@0:  * To build non-minimal HTML, use an HTML template language such as Twig,
Chris@0:  * rather than this class.
Chris@0:  *
Chris@0:  * @ingroup sanitization
Chris@0:  *
Chris@0:  * @see \Drupal\Core\StringTranslation\TranslatableMarkup
Chris@0:  * @see \Drupal\Core\StringTranslation\PluralTranslatableMarkup
Chris@0:  * @see \Drupal\Component\Render\FormattableMarkup::placeholderFormat()
Chris@0:  */
Chris@0: class FormattableMarkup implements MarkupInterface, \Countable {
Chris@0: 
Chris@0:   /**
Chris@14:    * The string containing placeholders.
Chris@14:    *
Chris@14:    * @var string
Chris@14:    */
Chris@14:   protected $string;
Chris@14: 
Chris@14:   /**
Chris@0:    * The arguments to replace placeholders with.
Chris@0:    *
Chris@0:    * @var array
Chris@0:    */
Chris@0:   protected $arguments = [];
Chris@0: 
Chris@0:   /**
Chris@0:    * Constructs a new class instance.
Chris@0:    *
Chris@0:    * @param string $string
Chris@0:    *   A string containing placeholders. The string itself will not be escaped,
Chris@0:    *   any unsafe content must be in $args and inserted via placeholders.
Chris@0:    * @param array $arguments
Chris@0:    *   An array with placeholder replacements, keyed by placeholder. See
Chris@0:    *   \Drupal\Component\Render\FormattableMarkup::placeholderFormat() for
Chris@0:    *   additional information about placeholders.
Chris@0:    *
Chris@0:    * @see \Drupal\Component\Render\FormattableMarkup::placeholderFormat()
Chris@0:    */
Chris@0:   public function __construct($string, array $arguments) {
Chris@0:     $this->string = (string) $string;
Chris@0:     $this->arguments = $arguments;
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * {@inheritdoc}
Chris@0:    */
Chris@0:   public function __toString() {
Chris@0:     return static::placeholderFormat($this->string, $this->arguments);
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * Returns the string length.
Chris@0:    *
Chris@0:    * @return int
Chris@0:    *   The length of the string.
Chris@0:    */
Chris@0:   public function count() {
Chris@17:     return mb_strlen($this->string);
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * Returns a representation of the object for use in JSON serialization.
Chris@0:    *
Chris@0:    * @return string
Chris@0:    *   The safe string content.
Chris@0:    */
Chris@0:   public function jsonSerialize() {
Chris@0:     return $this->__toString();
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * Replaces placeholders in a string with values.
Chris@0:    *
Chris@0:    * @param string $string
Chris@0:    *   A string containing placeholders. The string itself is expected to be
Chris@0:    *   safe and correct HTML. Any unsafe content must be in $args and
Chris@0:    *   inserted via placeholders.
Chris@0:    * @param array $args
Chris@0:    *   An associative array of replacements. Each array key should be the same
Chris@0:    *   as a placeholder in $string. The corresponding value should be a string
Chris@0:    *   or an object that implements
Chris@0:    *   \Drupal\Component\Render\MarkupInterface. The value replaces the
Chris@0:    *   placeholder in $string. Sanitization and formatting will be done before
Chris@0:    *   replacement. The type of sanitization and formatting depends on the first
Chris@0:    *   character of the key:
Chris@0:    *   - @variable: When the placeholder replacement value is:
Chris@0:    *     - A string, the replaced value in the returned string will be sanitized
Chris@0:    *       using \Drupal\Component\Utility\Html::escape().
Chris@0:    *     - A MarkupInterface object, the replaced value in the returned string
Chris@0:    *       will not be sanitized.
Chris@0:    *     - A MarkupInterface object cast to a string, the replaced value in the
Chris@0:    *       returned string be forcibly sanitized using
Chris@0:    *       \Drupal\Component\Utility\Html::escape().
Chris@0:    *       @code
Chris@0:    *         $this->placeholderFormat('This will force HTML-escaping of the replacement value: @text', ['@text' => (string) $safe_string_interface_object));
Chris@0:    *       @endcode
Chris@0:    *     Use this placeholder as the default choice for anything displayed on
Chris@0:    *     the site, but not within HTML attributes, JavaScript, or CSS. Doing so
Chris@0:    *     is a security risk.
Chris@0:    *   - %variable: Use when the replacement value is to be wrapped in <em>
Chris@0:    *     tags.
Chris@0:    *     A call like:
Chris@0:    *     @code
Chris@0:    *       $string = "%output_text";
Chris@0:    *       $arguments = ['%output_text' => 'text output here.'];
Chris@0:    *       $this->placeholderFormat($string, $arguments);
Chris@0:    *     @endcode
Chris@0:    *     makes the following HTML code:
Chris@0:    *     @code
Chris@0:    *       <em class="placeholder">text output here.</em>
Chris@0:    *     @endcode
Chris@0:    *     As with @variable, do not use this within HTML attributes, JavaScript,
Chris@0:    *     or CSS. Doing so is a security risk.
Chris@0:    *   - :variable: Return value is escaped with
Chris@0:    *     \Drupal\Component\Utility\Html::escape() and filtered for dangerous
Chris@0:    *     protocols using UrlHelper::stripDangerousProtocols(). Use this when
Chris@0:    *     using the "href" attribute, ensuring the attribute value is always
Chris@0:    *     wrapped in quotes:
Chris@0:    *     @code
Chris@0:    *     // Secure (with quotes):
Chris@0:    *     $this->placeholderFormat('<a href=":url">@variable</a>', [':url' => $url, '@variable' => $variable]);
Chris@0:    *     // Insecure (without quotes):
Chris@0:    *     $this->placeholderFormat('<a href=:url>@variable</a>', [':url' => $url, '@variable' => $variable]);
Chris@0:    *     @endcode
Chris@0:    *     When ":variable" comes from arbitrary user input, the result is secure,
Chris@0:    *     but not guaranteed to be a valid URL (which means the resulting output
Chris@0:    *     could fail HTML validation). To guarantee a valid URL, use
Chris@0:    *     Url::fromUri($user_input)->toString() (which either throws an exception
Chris@0:    *     or returns a well-formed URL) before passing the result into a
Chris@0:    *     ":variable" placeholder.
Chris@0:    *
Chris@0:    * @return string
Chris@0:    *   A formatted HTML string with the placeholders replaced.
Chris@0:    *
Chris@0:    * @ingroup sanitization
Chris@0:    *
Chris@0:    * @see \Drupal\Core\StringTranslation\TranslatableMarkup
Chris@0:    * @see \Drupal\Core\StringTranslation\PluralTranslatableMarkup
Chris@0:    * @see \Drupal\Component\Utility\Html::escape()
Chris@0:    * @see \Drupal\Component\Utility\UrlHelper::stripDangerousProtocols()
Chris@0:    * @see \Drupal\Core\Url::fromUri()
Chris@0:    */
Chris@0:   protected static function placeholderFormat($string, array $args) {
Chris@0:     // Transform arguments before inserting them.
Chris@0:     foreach ($args as $key => $value) {
Chris@0:       switch ($key[0]) {
Chris@0:         case '@':
Chris@0:           // Escape if the value is not an object from a class that implements
Chris@0:           // \Drupal\Component\Render\MarkupInterface, for example strings will
Chris@0:           // be escaped.
Chris@0:           // Strings that are safe within HTML fragments, but not within other
Chris@0:           // contexts, may still be an instance of
Chris@0:           // \Drupal\Component\Render\MarkupInterface, so this placeholder type
Chris@0:           // must not be used within HTML attributes, JavaScript, or CSS.
Chris@0:           $args[$key] = static::placeholderEscape($value);
Chris@0:           break;
Chris@0: 
Chris@0:         case ':':
Chris@0:           // Strip URL protocols that can be XSS vectors.
Chris@0:           $value = UrlHelper::stripDangerousProtocols($value);
Chris@0:           // Escape unconditionally, without checking whether the value is an
Chris@0:           // instance of \Drupal\Component\Render\MarkupInterface. This forces
Chris@0:           // characters that are unsafe for use in an "href" HTML attribute to
Chris@0:           // be encoded. If a caller wants to pass a value that is extracted
Chris@0:           // from HTML and therefore is already HTML encoded, it must invoke
Chris@0:           // \Drupal\Component\Render\OutputStrategyInterface::renderFromHtml()
Chris@0:           // on it prior to passing it in as a placeholder value of this type.
Chris@0:           // @todo Add some advice and stronger warnings.
Chris@0:           //   https://www.drupal.org/node/2569041.
Chris@0:           $args[$key] = Html::escape($value);
Chris@0:           break;
Chris@0: 
Chris@0:         case '%':
Chris@0:           // Similarly to @, escape non-safe values. Also, add wrapping markup
Chris@0:           // in order to render as a placeholder. Not for use within attributes,
Chris@0:           // per the warning above about
Chris@0:           // \Drupal\Component\Render\MarkupInterface and also due to the
Chris@0:           // wrapping markup.
Chris@0:           $args[$key] = '<em class="placeholder">' . static::placeholderEscape($value) . '</em>';
Chris@0:           break;
Chris@0: 
Chris@0:         default:
Chris@0:           // We do not trigger an error for placeholder that start with an
Chris@0:           // alphabetic character.
Chris@0:           // @todo https://www.drupal.org/node/2807743 Change to an exception
Chris@0:           //   and always throw regardless of the first character.
Chris@0:           if (!ctype_alpha($key[0])) {
Chris@0:             // We trigger an error as we may want to introduce new placeholders
Chris@0:             // in the future without breaking backward compatibility.
Chris@0:             trigger_error('Invalid placeholder (' . $key . ') in string: ' . $string, E_USER_ERROR);
Chris@0:           }
Chris@0:           elseif (strpos($string, $key) !== FALSE) {
Chris@0:             trigger_error('Invalid placeholder (' . $key . ') in string: ' . $string, E_USER_DEPRECATED);
Chris@0:           }
Chris@0:           // No replacement possible therefore we can discard the argument.
Chris@0:           unset($args[$key]);
Chris@0:           break;
Chris@0:       }
Chris@0:     }
Chris@0: 
Chris@0:     return strtr($string, $args);
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * Escapes a placeholder replacement value if needed.
Chris@0:    *
Chris@0:    * @param string|\Drupal\Component\Render\MarkupInterface $value
Chris@0:    *   A placeholder replacement value.
Chris@0:    *
Chris@0:    * @return string
Chris@0:    *   The properly escaped replacement value.
Chris@0:    */
Chris@0:   protected static function placeholderEscape($value) {
Chris@0:     return $value instanceof MarkupInterface ? (string) $value : Html::escape($value);
Chris@0:   }
Chris@0: 
Chris@0: }