MFB: Fixed bug #41347 (checkdnsrr() segfaults on empty hostname).

ext/standard/dns.c

@@ -263,6 +263,12 @@ PHP_FUNCTION(dns_check_record)
 		return;
 	}
 
+	if (hostname_len == 0)
+	{
+		php_error_docref(NULL TSRMLS_CC, E_WARNING, "Host cannot be empty");
+		RETURN_FALSE;
+	}
+
 	if (rectype) {
 		     if (!strcasecmp("A",     rectype)) type = T_A;
 		else if (!strcasecmp("NS",    rectype)) type = DNS_T_NS;

ext/standard/tests/network/bug41347.phpt

@@ -0,0 +1,15 @@
+--TEST--
+dns_check_record() segfault with empty host
+--SKIPIF--
+<?php
+if (substr(PHP_OS, 0, 3) == 'WIN') {
+    die('No windows support');
+}
+?>
+--FILE--
+<?php
+var_dump(dns_check_record(''));
+?>
+--EXPECTF--
+Warning: dns_check_record(): Host cannot be empty in %s on line %d
+bool(false)