/*
* Copyright 2010-2017 Amazon.com, Inc. or its affiliates. All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License").
* You may not use this file except in compliance with the License.
* A copy of the License is located at
*
* http://aws.amazon.com/apache2.0
*
* or in the "license" file accompanying this file. This file is distributed
* on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
* express or implied. See the License for the specific language governing
* permissions and limitations under the License.
*/
package com.amazonaws.http;
import com.amazonaws.SdkClientException;
import com.amazonaws.AmazonServiceException;
import com.amazonaws.annotation.SdkProtectedApi;
import com.amazonaws.transform.Unmarshaller;
import com.amazonaws.util.IOUtils;
import com.amazonaws.util.StringUtils;
import com.amazonaws.util.XpathUtils;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.w3c.dom.Document;
import org.w3c.dom.Node;
import org.xml.sax.SAXException;
import java.io.IOException;
import java.io.InputStream;
import java.util.List;
import javax.xml.parsers.ParserConfigurationException;
import static com.amazonaws.http.AmazonHttpClient.HEADER_SDK_TRANSACTION_ID;
/**
* Implementation of HttpResponseHandler that handles only error responses from Amazon Web Services.
* A list of unmarshallers is passed into the constructor, and while handling a response, each
* unmarshaller is tried, in order, until one is found that can successfully unmarshall the error
* response. If no unmarshaller is found that can unmarshall the error response, a generic
* AmazonServiceException is created and populated with the AWS error response information (error
* message, AWS error code, AWS request ID, etc).
*/
@SdkProtectedApi
public class DefaultErrorResponseHandler implements HttpResponseHandler<AmazonServiceException> {
private static final Log log = LogFactory.getLog(DefaultErrorResponseHandler.class);
/**
* The list of error response unmarshallers to try to apply to error responses.
*/
private List<Unmarshaller<AmazonServiceException, Node>> unmarshallerList;
/**
* Constructs a new DefaultErrorResponseHandler that will handle error responses from Amazon
* services using the specified list of unmarshallers. Each unmarshaller will be tried, in
* order, until one is found that can unmarshall the error response.
*
* @param unmarshallerList The list of unmarshallers to try using when handling an error
* response.
*/
public DefaultErrorResponseHandler(
List<Unmarshaller<AmazonServiceException, Node>> unmarshallerList) {
this.unmarshallerList = unmarshallerList;
}
@Override
public AmazonServiceException handle(HttpResponse errorResponse) throws Exception {
AmazonServiceException ase = createAse(errorResponse);
if (ase == null) {
throw new SdkClientException("Unable to unmarshall error response from service");
}
ase.setHttpHeaders(errorResponse.getHeaders());
if (StringUtils.isNullOrEmpty(ase.getErrorCode())) {
ase.setErrorCode(errorResponse.getStatusCode() + " " + errorResponse.getStatusText());
}
return ase;
}
private AmazonServiceException createAse(HttpResponse errorResponse) throws Exception {
// Try to parse the error response as XML
final Document document = documentFromContent(errorResponse.getContent(), idString(errorResponse));
/*
* We need to select which exception unmarshaller is the correct one to
* use from all the possible exceptions this operation can throw.
* Currently we rely on the unmarshallers to return null if they can't
* unmarshall the response, but we might need something a little more
* sophisticated in the future.
*/
for (Unmarshaller<AmazonServiceException, Node> unmarshaller : unmarshallerList) {
AmazonServiceException ase = unmarshaller.unmarshall(document);
if (ase != null) {
ase.setStatusCode(errorResponse.getStatusCode());
return ase;
}
}
return null;
}
private Document documentFromContent(InputStream content, String idString) throws ParserConfigurationException, SAXException, IOException {
try {
return parseXml(contentToString(content, idString), idString);
} catch (Exception e) {
// Generate an empty document to make the unmarshallers happy. Ultimately the default
// unmarshaller will be called to unmarshall into the service base exception.
return XpathUtils.documentFrom("<empty/>");
}
}
private String contentToString(InputStream content, String idString) throws Exception {
try {
return IOUtils.toString(content);
} catch (Exception e) {
log.info(String.format("Unable to read input stream to string (%s)", idString), e);
throw e;
}
}
private Document parseXml(String xml, String idString) throws Exception {
try {
return XpathUtils.documentFrom(xml);
} catch (Exception e) {
log.info(String.format("Unable to parse HTTP response (%s) content to XML document '%s' ", idString, xml), e);
throw e;
}
}
private String idString(HttpResponse errorResponse) {
StringBuilder idString = new StringBuilder();
try {
if (errorResponse.getRequest().getHeaders().containsKey(HEADER_SDK_TRANSACTION_ID)) {
idString.append("Invocation Id:").append(errorResponse.getRequest().getHeaders().get(HEADER_SDK_TRANSACTION_ID));
}
if (errorResponse.getHeaders().containsKey(X_AMZN_REQUEST_ID_HEADER)) {
if (idString.length() > 0) { idString.append(", "); }
idString.append("Request Id:").append(errorResponse.getHeaders().get(X_AMZN_REQUEST_ID_HEADER));
}
} catch (NullPointerException npe){
log.info("Error getting Request or Invocation ID from response", npe);
}
return idString.length() > 0 ? idString.toString() : "Unknown";
}
/**
* Since this response handler completely consumes all the data from the underlying HTTP
* connection during the handle method, we don't need to keep the HTTP connection open.
*
* @see com.amazonaws.http.HttpResponseHandler#needsConnectionLeftOpen()
*/
public boolean needsConnectionLeftOpen() {
return false;
}
}