Fix if already send error to http client, do not callback. (#19668)

Fixed #10435 

HttpListener already closes the Response object, closes the HTTP Client connection, and then sets the value of Response.StatusCode again. If so, an ObjectDisposedException is thrown.

```
Unhandled Exception:
System.ObjectDisposedException: Cannot access a disposed object.
Object name: 'System.Net.HttpListenerResponse'.
  at System.Net.HttpListenerResponse.set_ContentLength64 (System.Int64 value) [0x00013] in <b4473693dd3c4d45883c574a53529fbe>:0
  at MonoConsoleApp1.Program.Main (System.String[] args) [0x000f8] in <a66f6d7d417445dc9f89c691941ca70b>:0
  at MonoConsoleApp1.Program.<Main> (System.String[] args) [0x0000c] in <a66f6d7d417445dc9f89c691941ca70b>:0
[ERROR] FATAL UNHANDLED EXCEPTION: System.ObjectDisposedException: Cannot access a disposed object.
Object name: 'System.Net.HttpListenerResponse'.
  at System.Net.HttpListenerResponse.set_ContentLength64 (System.Int64 value) [0x00013] in <b4473693dd3c4d45883c574a53529fbe>:0
  at MonoConsoleApp1.Program.Main (System.String[] args) [0x000f8] in <a66f6d7d417445dc9f89c691941ca70b>:0
  at MonoConsoleApp1.Program.<Main> (System.String[] args) [0x0000c] in <a66f6d7d417445dc9f89c691941ca70b>:0
```

If an error is sent to the HTTP client while processing a request, it is patched so that the next process is not executed anymore.

Backport of #19664.

2 files changed, 13 insertions, 7 deletions

diff --git a/mcs/class/System/System.Net/HttpConnection.cs b/mcs/class/System/System.Net/HttpConnection.cs
index 90ddf31f17e..ddc9b80da90 100644
--- a/mcs/class/System/System.Net/HttpConnection.cs
+++ b/mcs/class/System/System.Net/HttpConnection.cs
@@ -237,8 +237,12 @@ namespace System.Net {
 			}
 
 			if (ProcessInput (ms)) {
-				if (!context.HaveError)
-					context.Request.FinishInitialization ();
+				if (!context.HaveError) {
+					if (!context.Request.FinishInitialization()) {
+						Close (true);
+						return;
+					}
+				}
 
 				if (context.HaveError) {
 					SendError ();
diff --git a/mcs/class/System/System.Net/HttpListenerRequest.cs b/mcs/class/System/System.Net/HttpListenerRequest.cs
index e351807aa3b..63aa0bcf518 100644
--- a/mcs/class/System/System.Net/HttpListenerRequest.cs
+++ b/mcs/class/System/System.Net/HttpListenerRequest.cs
@@ -192,12 +192,12 @@ namespace System.Net {
 			return false;
 		}
 
-		internal void FinishInitialization ()
+		internal bool FinishInitialization ()
 		{
 			string host = UserHostName;
 			if (version > HttpVersion.Version10 && (host == null || host.Length == 0)) {
 				context.ErrorMessage = "Invalid host name";
-				return;
+				return true;
 			}
 
 			string path;
@@ -223,7 +223,7 @@ namespace System.Net {
 
 			if (!Uri.TryCreate (base_uri + path, UriKind.Absolute, out url)){
 				context.ErrorMessage = WebUtility.HtmlEncode ("Invalid url: " + base_uri + path);
-				return;
+				return true;
 			}
 
 			CreateQueryString (url.Query);
@@ -239,7 +239,7 @@ namespace System.Net {
 				// 'identity' is not valid!
 				if (t_encoding != null && !is_chunked) {
 					context.Connection.SendError (null, 501);
-					return;
+					return false;
 				}
 			}
 
@@ -247,7 +247,7 @@ namespace System.Net {
 				if (String.Compare (method, "POST", StringComparison.OrdinalIgnoreCase) == 0 ||
 				    String.Compare (method, "PUT", StringComparison.OrdinalIgnoreCase) == 0) {
 					context.Connection.SendError (null, 411);
-					return;
+					return false;
 				}
 			}
 
@@ -255,6 +255,8 @@ namespace System.Net {
 				ResponseStream output = context.Connection.GetResponseStream ();
 				output.InternalWrite (_100continue, 0, _100continue.Length);
 			}
+
+			return true;
 		}
 
 		internal static string Unquote (String str) {