Fix email validation regex rejects addresses with single subdomain

dregad · dregad · commit abf661e7e394 · 2012-07-06T13:49:27.000+02:00
Per RFC 5322, e.g. user@localhost is a valid e-mail address but the
previously implemented regex rejected it.

Fixes #14453
diff --git a/core/email_api.php b/core/email_api.php
@@ -78,15 +78,24 @@
  $g_phpMailer = null;
 
 /**
- *
  * Use a simple perl regex for valid email addresses.  This is not a complete regex,
  * as it does not cover quoted addresses or domain literals, but it is simple and
  * covers the vast majority of all email addresses without being overly complex.
  * @return string
  */
 function email_regex_simple() {
-	return "/([a-z0-9!#*+\/=?^_{|}~-]+(?:\.[a-z0-9!#*+\/=?^_{|}~-]+)*)" . 				# recipient
-			"\@((?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?)/i";	# @domain
+	static $s_email_regex = null;
+
+	if( is_null( $s_email_regex ) ) {
+		$t_recipient = "([a-z0-9!#*+\/=?^_{|}~-]+(?:\.[a-z0-9!#*+\/=?^_{|}~-]+)*)";
+
+		# a domain is one or more subdomains
+		$t_subdomain = "(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?)";
+		$t_domain    = "(${t_subdomain}(?:\.${t_subdomain})*)";
+
+		$s_email_regex = "/${t_recipient}\@${t_domain}/";
+	}
+	return $s_email_regex;
 }
 
 /**
