Fix #935 retry on IOExceptions too. Refactoring of Helper classes into Chain of responsibility pattern.

msal4j-sdk/src/main/java/com/microsoft/aad/msal4j/AbstractClientApplicationBase.java

@@ -562,7 +562,7 @@ public T correlationId(String val) {
         super.serviceBundle = new ServiceBundle(
                 builder.executorService,
                 new TelemetryManager(telemetryConsumer, builder.onlySendFailureTelemetry),
-                new HttpHelper(this, new DefaultRetryPolicy())
+                new ThrottlingRequestChain(this, new DefaultRetryPolicy())
         );
 
         if (aadAadInstanceDiscoveryResponse != null) {

msal4j-sdk/src/main/java/com/microsoft/aad/msal4j/CorrelationIdRequestChain.java

@@ -0,0 +1,57 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License.
+
+package com.microsoft.aad.msal4j;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Correlation-id link of the HTTP request chain: verifies that the correlation id sent with the
+ * request matches the one returned in the response, once retries have been exhausted.
+ */
+class CorrelationIdRequestChain implements IRequestChain {
+    private static final Logger LOG = LoggerFactory.getLogger(CorrelationIdRequestChain.class);
+
+    private final IRequestChain next;
+
+    CorrelationIdRequestChain(IRequestChain next) {
+        this.next = next;
+    }
+
+    @Override
+    public IHttpResponse executeHttpRequest(HttpRequest httpRequest, RequestContext requestContext, ServiceBundle serviceBundle)
+            throws Exception {
+        IHttpResponse httpResponse = next.executeHttpRequest(httpRequest, requestContext, serviceBundle);
+
+        if (httpResponse.headers() != null) {
+            verifyReturnedCorrelationId(httpRequest, httpResponse);
+        }
+
+        return httpResponse;
+    }
+
+    private static void verifyReturnedCorrelationId(final HttpRequest httpRequest,
+                                                    IHttpResponse httpResponse) {
+
+        String sentCorrelationId = httpRequest.headerValue(
+                HttpHeaders.CORRELATION_ID_HEADER_NAME);
+
+        String returnedCorrelationId = HttpUtils.headerValue(
+                httpResponse.headers(),
+                HttpHeaders.CORRELATION_ID_HEADER_NAME);
+
+        if (StringHelper.isBlank(returnedCorrelationId) ||
+                !returnedCorrelationId.equals(sentCorrelationId)) {
+
+            String msg = LogHelper.createMessage(
+                    String.format(
+                            "Sent (%s) Correlation Id is not same as received (%s).",
+                            sentCorrelationId,
+                            returnedCorrelationId),
+                    sentCorrelationId);
+
+            LOG.info(msg);
+        }
+    }
+}

msal4j-sdk/src/main/java/com/microsoft/aad/msal4j/DefaultRetryPolicy.java

@@ -13,7 +13,7 @@ class DefaultRetryPolicy implements IRetryPolicy {
     @Override
     public boolean isRetryable(IHttpResponse httpResponse) {
         return HttpStatus.isServerError(httpResponse.statusCode()) &&
-                HttpHelper.getRetryAfterHeader(httpResponse) == null;
+                ThrottlingRequestChain.getRetryAfterHeader(httpResponse) == null;
     }
 
     @Override

msal4j-sdk/src/main/java/com/microsoft/aad/msal4j/DefaultRetryableExceptionPolicy.java

@@ -0,0 +1,35 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License.
+
+package com.microsoft.aad.msal4j;
+
+import java.net.SocketException;
+import java.net.SocketTimeoutException;
+import java.net.UnknownHostException;
+import javax.net.ssl.SSLException;
+
+/**
+ * Default policy for retrying HTTP requests that failed due to a network-level exception.
+ */
+class DefaultRetryableExceptionPolicy implements IRetryableExceptionPolicy {
+    private static final int RETRY_NUM = 1;
+    private static final int RETRY_DELAY_MS = 1000;
+
+    @Override
+    public boolean isRetryable(Exception exception) {
+        if (exception instanceof SSLException || exception instanceof UnknownHostException) {
+            return false;
+        }
+        return exception instanceof SocketException || exception instanceof SocketTimeoutException;
+    }
+
+    @Override
+    public int getMaxRetryCount(Exception exception) {
+        return RETRY_NUM;
+    }
+
+    @Override
+    public int getRetryDelayMs(Exception exception) {
+        return RETRY_DELAY_MS;
+    }
+}