avoid potential InvalidCastException when we already deal with bad/non-present extens...

diff --git a/mcs/class/System/System.Net/ServicePointManager.cs b/mcs/class/System/System.Net/ServicePointManager.cs
index c3714cf98e910463bceee93f02394b1c14519bd3..867ce387297e4421aaca9fe2fa431b202a937b80 100644 (file)
--- a/mcs/class/System/System.Net/ServicePointManager.cs
+++ b/mcs/class/System/System.Net/ServicePointManager.cs
@@ -638,8 +638,8 @@ namespace System.Net
                                        if (cert.Version < 3)
                                                return true;
 
-                                       X509KeyUsageExtension kux = (X509KeyUsageExtension) cert.Extensions ["2.5.29.15"];
-                                       X509EnhancedKeyUsageExtension eku = (X509EnhancedKeyUsageExtension) cert.Extensions ["2.5.29.37"];
+                                       X509KeyUsageExtension kux = (cert.Extensions ["2.5.29.15"] as X509KeyUsageExtension);
+                                       X509EnhancedKeyUsageExtension eku = (cert.Extensions ["2.5.29.37"] as X509EnhancedKeyUsageExtension);
                                        if (kux != null && eku != null) {
                                                // RFC3280 states that when both KeyUsageExtension and 
                                                // ExtendedKeyUsageExtension are present then BOTH should