1 files changed, 16 insertions, 0 deletions
diff --git a/src/System.Web.WebPages/RequestExtensions.cs b/src/System.Web.WebPages/RequestExtensions.cs
new file mode 100644
index 00000000..cde6c9ba
--- /dev/null
+++ b/src/System.Web.WebPages/RequestExtensions.cs
@@ -0,0 +1,16 @@
+using System.Diagnostics.CodeAnalysis;
+
+namespace System.Web.WebPages
+{
+    public static class RequestExtensions
+    {
+        [SuppressMessage("Microsoft.Usage", "CA1801:ReviewUnusedParameters", MessageId = "request", Justification = "The request parameter is no longer being used but we do not want to break legacy callers.")]
+        [SuppressMessage("Microsoft.Design", "CA1054:UriParametersShouldNotBeStrings", MessageId = "1#", Justification = "Response.Redirect() takes its URI as a string parameter.")]
+        public static bool IsUrlLocalToHost(this HttpRequestBase request, string url)
+        {
+            return !url.IsEmpty() &&
+                   ((url[0] == '/' && (url.Length == 1 || (url[1] != '/' && url[1] != '\\'))) || // "/" or "/foo" but not "//" or "/\"
+                    (url.Length > 1 && url[0] == '~' && url[1] == '/')); // "~/" or "~/foo"
+        }
+    }
+}