Make HttpListenerResponse.ContentEncoding a Nop in the managed implementation to match Windows (#19766)

* Cleanup some code in HttpListenerResponse

* Make HttpListenerResponse.ContentEncoding a Nop in the managed implementation to match Windows

* Address PR feedback

* Dispose of the HttpResponseMessage in HttpListener tests

Author: hughbe

src/System.Net.HttpListener/src/System/Net/HttpListenerResponse.cs

@@ -3,6 +3,7 @@
 // See the LICENSE file in the project root for more information.
 
 using System.Diagnostics;
+using System.Text;
 
 namespace System.Net
 {
@@ -13,10 +14,7 @@ public sealed unsafe partial class HttpListenerResponse : IDisposable
 
         public WebHeaderCollection Headers
         {
-            get
-            {
-                return _webHeaders;
-            }
+            get => _webHeaders;
             set
             {
                 _webHeaders = new WebHeaderCollection();
@@ -27,20 +25,12 @@ public WebHeaderCollection Headers
             }
         }
 
+        public Encoding ContentEncoding { get; set; }
+
         public CookieCollection Cookies
         {
-            get
-            {
-                if (_cookies == null)
-                {
-                    _cookies = new CookieCollection();
-                }
-                return _cookies;
-            }
-            set
-            {
-                _cookies = value;
-            }
+            get => _cookies ?? (_cookies = new CookieCollection());
+            set => _cookies = value;
         }
 
         public void AddHeader(string name, string value)
@@ -91,9 +81,6 @@ public void SetCookie(Cookie cookie)
             }
         }
 
-        void IDisposable.Dispose()
-        {
-            Dispose();
-        }
+        void IDisposable.Dispose() => Dispose();
     }
 }

src/System.Net.HttpListener/src/System/Net/Managed/HttpConnection.cs

@@ -450,7 +450,7 @@ public void SendError(string msg, int status)
                 else
                     str = string.Format("<h1>{0}</h1>", description);
 
-                byte[] error = _context.Response.ContentEncoding.GetBytes(str);
+                byte[] error = Encoding.Default.GetBytes(str);
                 response.Close(error, false);
             }
             catch

src/System.Net.HttpListener/src/System/Net/Managed/HttpListenerResponse.Managed.cs

@@ -38,7 +38,6 @@ namespace System.Net
     public sealed partial class HttpListenerResponse : IDisposable
     {
         private bool _disposed;
-        private Encoding _contentEncoding;
         private long _contentLength;
         private bool _clSet;
         private string _contentType;
@@ -59,37 +58,11 @@ internal HttpListenerResponse(HttpListenerContext context)
             _context = context;
         }
 
-        internal bool ForceCloseChunked
-        {
-            get { return _forceCloseChunked; }
-        }
-
-        public Encoding ContentEncoding
-        {
-            get
-            {
-                if (_contentEncoding == null)
-                {
-                    _contentEncoding = Encoding.Default;
-                }
-
-                return _contentEncoding;
-            }
-            set
-            {
-                if (_disposed)
-                    throw new ObjectDisposedException(GetType().ToString());
-
-                if (_headersSent)
-                    throw new InvalidOperationException(SR.net_cannot_change_after_headers);
-
-                _contentEncoding = value;
-            }
-        }
+        internal bool ForceCloseChunked => _forceCloseChunked;
 
         public long ContentLength64
         {
-            get { return _contentLength; }
+            get => _contentLength;
             set
             {
                 if (_disposed)
@@ -108,7 +81,7 @@ public long ContentLength64
 
         public string ContentType
         {
-            get { return _contentType; }
+            get => _contentType;
             set
             {
                 if (_disposed)
@@ -123,7 +96,7 @@ public string ContentType
 
         public bool KeepAlive
         {
-            get { return _keepAlive; }
+            get => _keepAlive;
             set
             {
                 if (_disposed)
@@ -148,7 +121,7 @@ public Stream OutputStream
 
         public Version ProtocolVersion
         {
-            get { return _version; }
+            get => _version;
             set
             {
                 if (_disposed)
@@ -169,7 +142,7 @@ public Version ProtocolVersion
 
         public string RedirectLocation
         {
-            get { return _location; }
+            get => _location;
             set
             {
                 if (_disposed)
@@ -184,7 +157,7 @@ public string RedirectLocation
 
         public bool SendChunked
         {
-            get { return _chunked; }
+            get => _chunked;
             set
             {
                 if (_disposed)
@@ -199,7 +172,7 @@ public bool SendChunked
 
         public int StatusCode
         {
-            get { return _statusCode; }
+            get => _statusCode;
             set
             {
                 if (_disposed)
@@ -217,17 +190,11 @@ public int StatusCode
 
         public string StatusDescription
         {
-            get { return _statusDescription; }
-            set
-            {
-                _statusDescription = value;
-            }
+            get => _statusDescription;
+            set => _statusDescription = value;
         }
 
-        private void Dispose()
-        {
-            Close(true);
-        }
+        private void Dispose() => Close(true);
 
         public void Close()
         {
@@ -301,23 +268,11 @@ private bool FindCookie(Cookie cookie)
 
         internal void SendHeaders(bool closing, MemoryStream ms, bool isWebSocketHandshake = false)
         {
-            Encoding encoding = _contentEncoding;
-            if (encoding == null)
-                encoding = Encoding.Default;
-
             if (!isWebSocketHandshake)
             {
                 if (_contentType != null)
                 {
-                    if (_contentEncoding != null && _contentType.IndexOf(HttpHeaderStrings.Charset, StringComparison.Ordinal) == -1)
-                    {
-                        string enc_name = _contentEncoding.WebName;
-                        _webHeaders.Set(HttpKnownHeaderNames.ContentType, _contentType + "; " + HttpHeaderStrings.Charset + enc_name);
-                    }
-                    else
-                    {
-                        _webHeaders.Set(HttpKnownHeaderNames.ContentType, _contentType);
-                    }
+                    _webHeaders.Set(HttpKnownHeaderNames.ContentType, _contentType);
                 }
 
                 if (_webHeaders[HttpKnownHeaderNames.Server] == null)
@@ -397,6 +352,7 @@ internal void SendHeaders(bool closing, MemoryStream ms, bool isWebSocketHandsha
                 }
             }
 
+            Encoding encoding = Encoding.Default;
             StreamWriter writer = new StreamWriter(ms, encoding, 256);
             writer.Write("HTTP/{0} {1} {2}\r\n", _version, _statusCode, _statusDescription);
             string headers_str = FormatHeaders(_webHeaders);