return error stream, if input stream could not be returned

scm-webapp/src/main/java/sonia/scm/net/ahc/DefaultAdvancedHttpResponse.java

@@ -33,11 +33,13 @@ package sonia.scm.net.ahc;
 
 //~--- non-JDK imports --------------------------------------------------------
 
-import com.google.common.collect.HashMultimap;
 import com.google.common.collect.LinkedHashMultimap;
 import com.google.common.collect.Multimap;
 import com.google.common.io.ByteSource;
 
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
 //~--- JDK imports ------------------------------------------------------------
 
 import java.io.IOException;
@@ -132,6 +134,14 @@ public class DefaultAdvancedHttpResponse extends AdvancedHttpResponse
   private static class URLConnectionByteSource extends ByteSource
   {
 
+    /**
+     * the logger for URLConnectionByteSource
+     */
+    private static final Logger logger =
+      LoggerFactory.getLogger(URLConnectionByteSource.class);
+
+    //~--- constructors -------------------------------------------------------
+
     /**
      * Constructs a new {@link URLConnectionByteSource}.
      *
@@ -146,17 +156,35 @@ public class DefaultAdvancedHttpResponse extends AdvancedHttpResponse
     //~--- methods ------------------------------------------------------------
 
     /**
-     * Opens the http connection.
+     * Opens the input stream of http connection, if an error occurs during
+     * opening the method will return the error stream instead.
      *
      *
-     * @return http connection
+     * @return input or error stream of http connection
      *
      * @throws IOException
      */
     @Override
     public InputStream openStream() throws IOException
     {
-      return connection.getInputStream();
+      InputStream stream;
+
+      try
+      {
+        stream = connection.getInputStream();
+      }
+      catch (IOException ex)
+      {
+        if (logger.isDebugEnabled())
+        {
+          logger.debug(
+            "could not open input stream, open error stream instead", ex);
+        }
+
+        stream = connection.getErrorStream();
+      }
+
+      return stream;
     }
 
     //~--- fields -------------------------------------------------------------

scm-webapp/src/test/java/sonia/scm/net/ahc/DefaultAdvancedHttpResponseTest.java

@@ -92,6 +92,28 @@ public class DefaultAdvancedHttpResponseTest
     assertEquals("test", content.asCharSource(Charsets.UTF_8).read());
   }
 
+  /**
+   * Method description
+   *
+   *
+   * @throws IOException
+   */
+  @Test
+  public void testContentAsByteSourceWithFailedRequest() throws IOException
+  {
+    ByteArrayInputStream bais =
+      new ByteArrayInputStream("test".getBytes(Charsets.UTF_8));
+
+    when(connection.getInputStream()).thenThrow(IOException.class);
+    when(connection.getErrorStream()).thenReturn(bais);
+
+    AdvancedHttpResponse response = new DefaultAdvancedHttpResponse(connection,
+                                      404, "NOT FOUND");
+    ByteSource content = response.contentAsByteSource();
+
+    assertEquals("test", content.asCharSource(Charsets.UTF_8).read());
+  }
+
   /**
    * Method description
    *