Adjusting to connection close as default for HttpClient (#396)

Author: Ellerbach

nanoFramework.System.Net.Http/Http/Headers/HttpRequestHeaders.cs

@@ -43,12 +43,20 @@ public bool ConnectionClose
         {
             get
             {
-                return Connection.Contains("close");
+                return Connection.ToLower().Contains("close");
             }
 
             set
             {
-                throw new NotImplementedException();
+                var connectionHeader = _headerStore.GetValues(HttpKnownHeaderNames.Connection);
+                if (connectionHeader is not null)
+                {
+                    connectionHeader[0] = value ? "close" : "keep-alive";
+                }
+                else
+                {
+                    _headerStore.AddInternal(HttpKnownHeaderNames.Connection, value ? "close" : "keep-alive");
+                }
             }
         }
 

nanoFramework.System.Net.Http/Http/HttpClient.cs

@@ -140,6 +140,9 @@ public HttpClient() : base(
             true)
         {
             _timeout = Threading.Timeout.InfiniteTimeSpan;
+
+            // The default in REST API is to close the connection after each request.
+            DefaultRequestHeaders.ConnectionClose = true;
         }
 
         #endregion Constructors

nanoFramework.System.Net.Http/Http/HttpClientHandler.cs

@@ -262,7 +262,7 @@ protected internal override HttpResponseMessage Send(HttpRequestMessage request)
             {
                 throw new HttpRequestException("An error occurred while sending the request", ex);
             }
-            
+
             return CreateResponseMessage(wresponse, request);
         }
 
@@ -348,7 +348,8 @@ HttpResponseMessage CreateResponseMessage(HttpWebResponse wr, HttpRequestMessage
 
         bool GetConnectionKeepAlive(HttpRequestHeaders headers)
         {
-            return headers.Connection.Equals("Keep-Alive");
+            // In theory, the value should be lower case but it can with upper case.
+            return headers.Connection.ToLower().Equals("keep-alive");
         }
 
         internal void EnsureModifiability()

nanoFramework.System.Net.Http/Http/System.Net.HttpWebRequest.cs

@@ -1240,14 +1240,16 @@ private void PrepareHeaders()
                 // Otherwise: we send "Connection:Close" or "Connection:Keep-Alive"
                 if (m_httpRequestHeaders[HttpKnownHeaderNames.Connection] == null)
                 {
-                    string connectionValue;
+                    string connectionValue;                    
                     if (m_keepAlive)
                     {
-                        connectionValue = "Keep-Alive";
+                        // According to RFC, should be lower case
+                        connectionValue = "keep-alive";
                     }
                     else
                     {
-                        connectionValue = "Close";
+                        // According to RFC, should be lower case
+                        connectionValue = "close";
                     }
 
                     m_httpRequestHeaders.ChangeInternal(HttpKnownHeaderNames.Connection, connectionValue);