Fix path security bug and added features

Tesses.WebServer.NetStandard/ServerContext.cs

@@ -2,6 +2,7 @@
 using System.IO;
 using System;
 using System.Net;
+using System.Text;
 
 namespace Tesses.WebServer
 {
@@ -70,6 +71,20 @@ internal class SizedStream : Stream
 }
     public class ServerContext
     {
+        const string bad_chars = "<>?/\\\"*|:";
+        public static string FixFileName(string filename,bool requireAscii=false)
+        {
+            StringBuilder builder=new StringBuilder();
+            foreach(var c in filename)
+            {
+                if(char.IsControl(c)) continue;
+                if(requireAscii && c > 127) continue;
+                if(bad_chars.Contains(c.ToString())) continue;
+                builder.Append(c);
+            }
+
+            return builder.ToString();
+        }
         /// <summary>
         /// Some user data
         /// </summary>
@@ -277,6 +292,10 @@ internal class SizedStream : Stream
                      return new SizedStream(NetworkStream,len);
                 }
             }
+            else if(RequestHeaders.TryGetFirst("Transfer-Encoding",out var res) && res == "chunked")
+            {
+                return new ChunkedStream(NetworkStream,true);
+            }
             //DajuricSimpleHttpExtensions.Print("Returns NetworkStream");
             return NetworkStream;
         }