Parse service error for get twin failures - mqtt (#2999)

iothub/device/src/Exceptions/IotHubClientErrorCode.cs

@@ -72,7 +72,7 @@ public enum IotHubClientErrorCode
         /// Retrying with exponential back-off could resolve this error. For information on the IoT hub quotas and
         /// throttling, see <see href="https://docs.microsoft.com/azure/iot-hub/iot-hub-devguide-quotas-throttling"/>.
         /// </remark>
-        Throttled,
+        Throttled = 429,
 
         /// <summary>
         /// The ETag in the request does not match the ETag of the existing resource.

iothub/device/src/Exceptions/IotHubClientErrorResponseMessage.cs

@@ -11,7 +11,7 @@ namespace Microsoft.Azure.Devices.Client
     internal class IotHubClientErrorResponseMessage
     {
         [JsonProperty("errorCode")]
-        internal string ErrorCode { get; set; }
+        internal int ErrorCode { get; set; }
 
         [JsonProperty("trackingId")]
         internal string TrackingId { get; set; }

iothub/device/src/Transport/Mqtt/GetTwinResponse.cs

@@ -30,6 +30,6 @@ internal class GetTwinResponse
         /// <summary>
         /// The error message if the request failed.
         /// </summary>
-        internal string Message { get; set; }
+        internal IotHubClientErrorResponseMessage ErrorResponseMessage { get; set; }
     }
 }

iothub/device/src/Transport/Mqtt/MqttTransportHandler.cs

@@ -639,9 +639,23 @@ public override async Task<TwinProperties> GetTwinAsync(CancellationToken cancel
 
                 if (getTwinResponse.Status != 200)
                 {
-                    throw new IotHubClientException(
-                        getTwinResponse.Message,
-                        IotHubClientErrorCode.NetworkErrors);
+                    // Check if we have an int to string error code translation for the service returned error code.
+                    // The error code could be a part of the service returned error message, or it can be a part of the topic string.
+                    // We will check with the error code in the error message first (if present) since that is the more specific error code returned.
+                    if ((Enum.TryParse(getTwinResponse.ErrorResponseMessage.ErrorCode.ToString(), out IotHubClientErrorCode errorCode)
+                        || Enum.TryParse(getTwinResponse.Status.ToString(), out errorCode))
+                        && Enum.IsDefined(typeof(IotHubClientErrorCode), errorCode))
+                    {
+                        throw new IotHubClientException(getTwinResponse.ErrorResponseMessage.Message, errorCode)
+                        {
+                            TrackingId = getTwinResponse.ErrorResponseMessage.TrackingId,
+                        };
+                    }
+
+                    throw new IotHubClientException(getTwinResponse.ErrorResponseMessage.Message)
+                    {
+                        TrackingId = getTwinResponse.ErrorResponseMessage.TrackingId,
+                    };
                 }
 
                 return getTwinResponse.Twin;
@@ -727,18 +741,23 @@ public override async Task<long> UpdateReportedPropertiesAsync(ReportedPropertie
 
                 if (patchTwinResponse.Status != 204)
                 {
-                    if (Enum.TryParse(patchTwinResponse.ErrorResponseMessage.ErrorCode, out IotHubClientErrorCode errorCode))
+                    // Check if we have an int to string error code translation for the service returned error code.
+                    // The error code could be a part of the service returned error message, or it can be a part of the topic string.
+                    // We will check with the error code in the error message first (if present) since that is the more specific error code returned.
+                    if ((Enum.TryParse(patchTwinResponse.ErrorResponseMessage.ErrorCode.ToString(), out IotHubClientErrorCode errorCode)
+                        || Enum.TryParse(patchTwinResponse.Status.ToString(), out errorCode))
+                        && Enum.IsDefined(typeof(IotHubClientErrorCode), errorCode))
                     {
                         throw new IotHubClientException(patchTwinResponse.ErrorResponseMessage.Message, errorCode)
                         {
-                            TrackingId = patchTwinResponse.ErrorResponseMessage.TrackingId
+                            TrackingId = patchTwinResponse.ErrorResponseMessage.TrackingId,
                         };
                     }
 
                     throw new IotHubClientException(patchTwinResponse.ErrorResponseMessage.Message)
                     {
-                        TrackingId = patchTwinResponse.ErrorResponseMessage.TrackingId
-                    }; ;
+                        TrackingId = patchTwinResponse.ErrorResponseMessage.TrackingId,
+                    };
                 }
 
                 return patchTwinResponse.Version;
@@ -1061,10 +1080,33 @@ private void HandleTwinResponse(MqttApplicationMessageReceivedEventArgs received
 
                     if (status != 200)
                     {
+                        IotHubClientErrorResponseMessage errorResponse = null;
+
+                        // This will only ever contain an error message which is encoded based on service contract (UTF-8).
+                        if (payloadBytes.Length > 0)
+                        {
+                            string errorResponseString = Encoding.UTF8.GetString(payloadBytes);
+                            try
+                            {
+                                errorResponse = JsonConvert.DeserializeObject<IotHubClientErrorResponseMessage>(errorResponseString);
+                            }
+                            catch (JsonException ex)
+                            {
+                                if (Logging.IsEnabled)
+                                    Logging.Error(this, $"Failed to parse twin patch error response JSON. Message body: '{errorResponseString}'. Exception: {ex}. ");
+
+                                errorResponse = new IotHubClientErrorResponseMessage
+                                {
+                                    Message = errorResponseString,
+                                };
+                            }
+                        }
+
+                        // This received message is in response to an update reported properties request.
                         var getTwinResponse = new GetTwinResponse
                         {
                             Status = status,
-                            Message = Encoding.UTF8.GetString(payloadBytes), // The error message is encoded based on service contract, which is UTF-8.
+                            ErrorResponseMessage = errorResponse,
                         };
 
                         getTwinCompletion.TrySetResult(getTwinResponse);
@@ -1104,7 +1146,7 @@ private void HandleTwinResponse(MqttApplicationMessageReceivedEventArgs received
                         catch (JsonReaderException ex)
                         {
                             if (Logging.IsEnabled)
-                                Logging.Error(this, $"Failed to parse Twin JSON: {ex}. Message body: '{Encoding.UTF8.GetString(payloadBytes)}'");
+                                Logging.Error(this, $"Failed to parse Twin JSON.  Message body: '{Encoding.UTF8.GetString(payloadBytes)}'. Exception: {ex}.");
 
                             getTwinCompletion.TrySetException(ex);
                         }
@@ -1128,7 +1170,7 @@ private void HandleTwinResponse(MqttApplicationMessageReceivedEventArgs received
                         catch (JsonException ex)
                         {
                             if (Logging.IsEnabled)
-                                Logging.Error(this, $"Failed to parse twin patch error response JSON: {ex}. Message body: '{errorResponseString}'");
+                                Logging.Error(this, $"Failed to parse twin patch error response JSON. Message body: '{errorResponseString}'. Exception: {ex}. ");
 
                             errorResponse = new IotHubClientErrorResponseMessage
                             {