From 99c9349c7430d7f31e4b90583339f2da70e5cdae Mon Sep 17 00:00:00 2001
From: Guillaume Perrot <guperrot@microsoft.com>
Date: Thu, 8 Dec 2016 19:08:39 -0800
Subject: [PATCH]  #270 Retry transient ssl exceptions

---
 .../ingestion/http/HttpUtilsAndroidTest.java  |  8 ++++++
 .../mobile/ingestion/http/HttpUtils.java      | 28 ++++++++++++++++++-
 2 files changed, 35 insertions(+), 1 deletion(-)

diff --git a/sdk/mobile-center/src/androidTest/java/com/microsoft/azure/mobile/ingestion/http/HttpUtilsAndroidTest.java b/sdk/mobile-center/src/androidTest/java/com/microsoft/azure/mobile/ingestion/http/HttpUtilsAndroidTest.java
index e9c4195185..dc648b74bd 100644
--- a/sdk/mobile-center/src/androidTest/java/com/microsoft/azure/mobile/ingestion/http/HttpUtilsAndroidTest.java
+++ b/sdk/mobile-center/src/androidTest/java/com/microsoft/azure/mobile/ingestion/http/HttpUtilsAndroidTest.java
@@ -10,6 +10,9 @@
 import java.net.SocketTimeoutException;
 import java.net.UnknownHostException;
 
+import javax.net.ssl.SSLException;
+import javax.net.ssl.SSLHandshakeException;
+
 import static com.microsoft.azure.mobile.ingestion.http.HttpUtils.isRecoverableError;
 import static junit.framework.Assert.assertFalse;
 import static junit.framework.Assert.assertTrue;
@@ -39,5 +42,10 @@ public void isRecoverableErrorTest() {
         assertFalse(isRecoverableError(new HttpException(413)));
         assertTrue(isRecoverableError(new HttpException(429)));
         assertTrue(isRecoverableError(new HttpException(401)));
+        assertTrue(isRecoverableError(new SSLException("Write error: ssl=0x59c28f90: I/O error during system call, Connection timed out")));
+        assertFalse(isRecoverableError(new SSLHandshakeException("java.security.cert.CertPathValidatorException: Trust anchor for certification path not found.")));
+        assertFalse(isRecoverableError(new SSLException("java.lang.RuntimeException: Unexpected error: java.security.InvalidAlgorithmParameterException: the trustAnchors parameter must be non-empty")));
+        assertTrue(isRecoverableError(new SSLException("Read error: ssl=0x9dd07200: I/O error during system call, Connection reset by peer")));
+        assertTrue(isRecoverableError(new SSLException("SSL handshake aborted: ssl=0x1cc160: I/O error during system call, Connection reset by peer")));
     }
 }
diff --git a/sdk/mobile-center/src/main/java/com/microsoft/azure/mobile/ingestion/http/HttpUtils.java b/sdk/mobile-center/src/main/java/com/microsoft/azure/mobile/ingestion/http/HttpUtils.java
index 368749596c..a05ecf54ab 100644
--- a/sdk/mobile-center/src/main/java/com/microsoft/azure/mobile/ingestion/http/HttpUtils.java
+++ b/sdk/mobile-center/src/main/java/com/microsoft/azure/mobile/ingestion/http/HttpUtils.java
@@ -6,9 +6,18 @@
 import java.io.InterruptedIOException;
 import java.net.SocketException;
 import java.net.UnknownHostException;
+import java.util.regex.Pattern;
 
+import javax.net.ssl.SSLException;
+
+/**
+ * HTTP utilities.
+ */
 public final class HttpUtils {
 
+    /**
+     * Types of exception that can be retried, no matter what the details are. Sub-classes are included.
+     */
     private static final Class[] RECOVERABLE_EXCEPTIONS = {
             EOFException.class,
             InterruptedIOException.class,
@@ -16,19 +25,36 @@ public final class HttpUtils {
             UnknownHostException.class
     };
 
+    /**
+     * Some transient exceptions can only be detected by interpreting the message...
+     */
+    private static Pattern CONNECTION_ISSUE_PATTERN = Pattern.compile("connection (time|reset)");
+
     @VisibleForTesting
     HttpUtils() {
     }
 
+    /**
+     * Check whether an exception/error describes a recoverable error or not.
+     *
+     * @param t exception or error.
+     * @return true if the exception/error should be retried, false otherwise.
+     */
     public static boolean isRecoverableError(Throwable t) {
+
+        /* Check HTTP exception details. */
         if (t instanceof HttpException) {
             HttpException exception = (HttpException) t;
             int code = exception.getStatusCode();
             return code >= 500 || code == 408 || code == 429 || code == 401;
         }
+
+        /* Check for a generic exception to retry. */
         for (Class<?> type : RECOVERABLE_EXCEPTIONS)
             if (type.isAssignableFrom(t.getClass()))
                 return true;
-        return false;
+
+        /* Check corner cases. */
+        return t instanceof SSLException && CONNECTION_ISSUE_PATTERN.matcher(t.getMessage().toLowerCase()).find();
     }
 }