diff core/lib/Drupal/Component/Utility/Mail.php @ 17:129ea1e6d783

Update, including to Drupal core 8.6.10

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/core/lib/Drupal/Component/Utility/Mail.php	Thu Feb 28 13:21:36 2019 +0000
@@ -0,0 +1,67 @@
+<?php
+
+namespace Drupal\Component\Utility;
+
+/**
+ * Provides helpers to ensure emails are compliant with RFCs.
+ *
+ * @ingroup utility
+ */
+class Mail {
+
+  /**
+   * RFC-2822 "specials" characters.
+   */
+  const RFC_2822_SPECIALS = '()<>[]:;@\,."';
+
+  /**
+   * Return a RFC-2822 compliant "display-name" component.
+   *
+   * The "display-name" component is used in mail header "Originator" fields
+   * (From, Sender, Reply-to) to give a human-friendly description of the
+   * address, i.e. From: My Display Name <[e-mail]>. RFC-822 and
+   * RFC-2822 define its syntax and rules. This method gets as input a string
+   * to be used as "display-name" and formats it to be RFC compliant.
+   *
+   * @param string $string
+   *   A string to be used as "display-name".
+   *
+   * @return string
+   *   A RFC compliant version of the string, ready to be used as
+   *   "display-name" in mail originator header fields.
+   */
+  public static function formatDisplayName($string) {
+    // Make sure we don't process html-encoded characters. They may create
+    // unneeded trouble if left encoded, besides they will be correctly
+    // processed if decoded.
+    $string = Html::decodeEntities($string);
+
+    // If string contains non-ASCII characters it must be (short) encoded
+    // according to RFC-2047. The output of a "B" (Base64) encoded-word is
+    // always safe to be used as display-name.
+    $safe_display_name = Unicode::mimeHeaderEncode($string, TRUE);
+
+    // Encoded-words are always safe to be used as display-name because don't
+    // contain any RFC 2822 "specials" characters. However
+    // Unicode::mimeHeaderEncode() encodes a string only if it contains any
+    // non-ASCII characters, and leaves its value untouched (un-encoded) if
+    // ASCII only. For this reason in order to produce a valid display-name we
+    // still need to make sure there are no "specials" characters left.
+    if (preg_match('/[' . preg_quote(Mail::RFC_2822_SPECIALS) . ']/', $safe_display_name)) {
+
+      // If string is already quoted, it may or may not be escaped properly, so
+      // don't trust it and reset.
+      if (preg_match('/^"(.+)"$/', $safe_display_name, $matches)) {
+        $safe_display_name = str_replace(['\\\\', '\\"'], ['\\', '"'], $matches[1]);
+      }
+
+      // Transform the string in a RFC-2822 "quoted-string" by wrapping it in
+      // double-quotes. Also make sure '"' and '\' occurrences are escaped.
+      $safe_display_name = '"' . str_replace(['\\', '"'], ['\\\\', '\\"'], $safe_display_name) . '"';
+
+    }
+
+    return $safe_display_name;
+  }
+
+}