show warning if session cookie domain is ip

closes #2007

flask/helpers.py

@@ -976,3 +976,23 @@ def total_seconds(td):
     :rtype: int
     """
     return td.days * 60 * 60 * 24 + td.seconds
+
+def is_ip(ip):
+    """Returns the if the string received is an IP or not.
+
+    :param string: the string to check if it an IP or not
+    :param var_name: the name of the string that is being checked
+
+    :returns: True if string is an IP, False if not
+    :rtype: boolean
+    """
+    import socket
+
+    for family in (socket.AF_INET, socket.AF_INET6):
+        try:
+            socket.inet_pton(family, ip)
+        except socket.error:
+            pass
+        else:
+            return True
+    return False