Accept compressed responses from the backend. (#817)

Author: rlazo

transport/transport-backend-cct/src/main/java/com/google/android/datatransport/cct/CctTransportBackend.java

@@ -55,6 +55,7 @@
 import java.util.List;
 import java.util.Map;
 import java.util.TimeZone;
+import java.util.zip.GZIPInputStream;
 import java.util.zip.GZIPOutputStream;
 
 final class CctTransportBackend implements TransportBackend {
@@ -63,6 +64,7 @@ final class CctTransportBackend implements TransportBackend {
 
   private static final int CONNECTION_TIME_OUT = 30000;
   private static final int READ_TIME_OUT = 40000;
+  private static final String ACCEPT_ENCODING_HEADER_KEY = "Accept-Encoding";
   private static final String CONTENT_ENCODING_HEADER_KEY = "Content-Encoding";
   private static final String GZIP_CONTENT_ENCODING = "gzip";
   private static final String CONTENT_TYPE_HEADER_KEY = "Content-Type";
@@ -226,6 +228,7 @@ private HttpResponse doSend(HttpRequest request) throws IOException {
         "User-Agent", String.format("datatransport/%s android/", BuildConfig.VERSION_NAME));
     connection.setRequestProperty(CONTENT_ENCODING_HEADER_KEY, GZIP_CONTENT_ENCODING);
     connection.setRequestProperty(CONTENT_TYPE_HEADER_KEY, PROTOBUF_CONTENT_TYPE);
+    connection.setRequestProperty(ACCEPT_ENCODING_HEADER_KEY, GZIP_CONTENT_ENCODING);
 
     if (request.apiKey != null) {
       connection.setRequestProperty(API_KEY_HEADER_KEY, request.apiKey);
@@ -244,7 +247,8 @@ private HttpResponse doSend(HttpRequest request) throws IOException {
       channel.write(ByteBuffer.wrap(output.toByteArray()));
       int responseCode = connection.getResponseCode();
       Logging.i(LOG_TAG, "Status Code: " + responseCode);
-      Logging.i(LOG_TAG, "Content-Type:" + connection.getHeaderField("Content-Type"));
+      Logging.i(LOG_TAG, "Content-Type: " + connection.getHeaderField("Content-Type"));
+      Logging.i(LOG_TAG, "Content-Encoding: " + connection.getHeaderField("Content-Encoding"));
 
       if (responseCode == 302 || responseCode == 301) {
         String redirect = connection.getHeaderField("Location");
@@ -254,7 +258,13 @@ private HttpResponse doSend(HttpRequest request) throws IOException {
         return new HttpResponse(responseCode, null, 0);
       }
 
-      InputStream inputStream = connection.getInputStream();
+      InputStream inputStream;
+      String contentEncoding = connection.getHeaderField(CONTENT_ENCODING_HEADER_KEY);
+      if (contentEncoding != null && contentEncoding.equals(GZIP_CONTENT_ENCODING)) {
+        inputStream = new GZIPInputStream(connection.getInputStream());
+      } else {
+        inputStream = connection.getInputStream();
+      }
       try {
         long nextRequestMillis = LogResponse.parseFrom(inputStream).getNextRequestWaitMillis();
         return new HttpResponse(responseCode, null, nextRequestMillis);

transport/transport-backend-cct/src/test/java/com/google/android/datatransport/cct/CctTransportBackendTest.java

@@ -43,7 +43,9 @@
 import com.google.android.datatransport.runtime.backends.BackendResponse;
 import com.google.android.datatransport.runtime.time.TestClock;
 import com.google.protobuf.ByteString;
+import java.io.ByteArrayOutputStream;
 import java.util.Arrays;
+import java.util.zip.GZIPOutputStream;
 import org.junit.Rule;
 import org.junit.Test;
 import org.junit.runner.RunWith;
@@ -368,6 +370,37 @@ public void send_whenBackendRedirectsMoreThan5Times_shouldOnlyRedirect4Times() {
     assertEquals(BackendResponse.fatalError(), response);
   }
 
+  @Test
+  public void send_CompressedResponseIsUncompressed() throws Exception {
+    ByteArrayOutputStream output = new ByteArrayOutputStream();
+    GZIPOutputStream gzipOutputStream = new GZIPOutputStream(output);
+    gzipOutputStream.write(
+        LogResponse.newBuilder().setNextRequestWaitMillis(3).build().toByteArray());
+    gzipOutputStream.close();
+
+    stubFor(
+        post(urlEqualTo("/api"))
+            .willReturn(
+                aResponse()
+                    .withStatus(200)
+                    .withHeader("Content-Type", "application/x-protobuf;charset=UTF8;hello=world")
+                    .withHeader("Content-Encoding", "gzip")
+                    .withBody(output.toByteArray())));
+
+    BackendRequest backendRequest = getCCTBackendRequest();
+    wallClock.tick();
+    uptimeClock.tick();
+
+    BackendResponse response = BACKEND.send(backendRequest);
+
+    verify(
+        postRequestedFor(urlEqualTo("/api"))
+            .withHeader("Content-Type", equalTo("application/x-protobuf"))
+            .withHeader("Content-Encoding", equalTo("gzip")));
+
+    assertEquals(BackendResponse.ok(3), response);
+  }
+
   // When there is no active network, the ConnectivityManager returns null when
   // getActiveNetworkInfo() is called.
   @Implements(ConnectivityManager.class)