[AndroidClientHandler] Wrap Java exceptions in .NET ones

Context: 60363ef

This commit a follow-up to 60363ef in that it causes less Java
exceptions to "leak" to applications which use code shared between
platforms that might not be able to check for Java exception types
directly (because they don't link against `Mono.Android.dll`).  However,
instead of making the behavior optional, as implemented in 60363ef,
this commit unconditionally wraps `Java.IO.Exception` and some of its
derivatives in the standard .NET `WebException`.  This makes the handler
to behave in a manner that's closer to how other `HttpClient` custom
handlers behave.

The `$(AndroidBoundExceptionType)` MSBuild property must be set to
`System` in order to use the wrapped exceptions.

Author: grendello

src/Mono.Android/Xamarin.Android.Net/AndroidClientHandler.cs

@@ -282,14 +282,24 @@ string EncodeUrl (Uri url)
 				if (ReadTimeout != TimeSpan.Zero)
 					java_connection!.ReadTimeout = checked ((int)ReadTimeout.TotalMilliseconds);
 
-				HttpURLConnection httpConnection = await SetupRequestInternal (request, java_connection!).ConfigureAwait (continueOnCapturedContext: false);;
-				var response = await ProcessRequest (request, java_url, httpConnection, cancellationToken, redirectState).ConfigureAwait (continueOnCapturedContext: false);;
-				if (response != null)
-					return response;
-
-				if (redirectState.NewUrl == null)
-					throw new InvalidOperationException ("Request redirected but no new URI specified");
-				request.Method = redirectState.Method;
+				try {
+					HttpURLConnection httpConnection = await SetupRequestInternal (request, java_connection!).ConfigureAwait (continueOnCapturedContext: false);
+					HttpResponseMessage? response = await ProcessRequest (request, java_url, httpConnection, cancellationToken, redirectState).ConfigureAwait (continueOnCapturedContext: false);
+					if (response != null)
+						return response;
+
+					if (redirectState.NewUrl == null)
+						throw new InvalidOperationException ("Request redirected but no new URI specified");
+					request.Method = redirectState.Method;
+				} catch (Java.Net.SocketTimeoutException ex) when (JNIEnv.ShouldWrapJavaException (ex)) {
+					throw new WebException (ex.Message, ex, WebExceptionStatus.Timeout, null);
+				} catch (Java.Net.UnknownServiceException ex) when (JNIEnv.ShouldWrapJavaException (ex)) {
+					throw new WebException (ex.Message, ex, WebExceptionStatus.ProtocolError, null);
+				} catch (Java.Lang.SecurityException ex) when (JNIEnv.ShouldWrapJavaException (ex)) {
+					throw new WebException (ex.Message, ex, WebExceptionStatus.SecureChannelFailure, null);
+				} catch (Java.IO.IOException ex) when (JNIEnv.ShouldWrapJavaException (ex)) {
+					throw new WebException (ex.Message, ex, WebExceptionStatus.UnknownError, null);
+				}
 			}
 		}
 
@@ -339,8 +349,11 @@ Task ConnectAsync (HttpURLConnection httpConnection, CancellationToken ct)
 							if (t.Exception != null) Logger.Log(LogLevel.Info, LOG_APP, $"Disconnection exception: {t.Exception}");
 						}, TaskScheduler.Default)))
 						httpConnection?.Connect ();
-				} catch {
-					ct.ThrowIfCancellationRequested ();
+				} catch (Exception ex) {
+					if (ct.IsCancellationRequested) {
+						Logger.Log (LogLevel.Info, LOG_APP, $"Exception caught while cancelling connection: {ex}");
+						ct.ThrowIfCancellationRequested ();
+					}
 					throw;
 				}
 			}, ct);
@@ -449,8 +462,7 @@ protected virtual async Task WriteRequestContentToOutput (HttpRequestMessage req
 				if (Logger.LogNet)
 					Logger.Log (LogLevel.Info, LOG_APP, $"Reading...");
 				ret.Content = GetContent (httpConnection, httpConnection.InputStream!);
-			}
-			else {
+			} else {
 				if (Logger.LogNet)
 					Logger.Log (LogLevel.Info, LOG_APP, $"Status code is {statusCode}, reading...");
 				// For 400 >= response code <= 599 the Java client throws the FileNotFound exception when attempting to read from the input stream.
@@ -818,7 +830,11 @@ void AppendEncoding (string encoding, ref List <string>? list)
 			if (httpConnection == null)
 				throw new InvalidOperationException ($"Unsupported URL scheme {conn.URL?.Protocol}");
 
-			httpConnection.RequestMethod = request.Method.ToString ();
+			try {
+				httpConnection.RequestMethod = request.Method.ToString ();
+			} catch (Java.Net.ProtocolException ex) when (JNIEnv.ShouldWrapJavaException (ex)) {
+				throw new WebException (ex.Message, ex, WebExceptionStatus.ProtocolError, null);
+			}
 
 			// SSL context must be set up as soon as possible, before adding any content or
 			// headers. Otherwise Java won't use the socket factory