Tightening up error message for GO_AWAY.

The attempt here is to identify all causes of GO_AWAY and to ensure
there is a reasonable description to help understand the cause.

Fixes #163

core/src/main/java/io/grpc/transport/HttpUtil.java

@@ -121,5 +121,88 @@ public final class HttpUtil {
     return Status.UNKNOWN;
   }
 
+  /**
+   * All error codes identified by the HTTP/2 spec.
+   */
+  public enum Http2Error {
+    NO_ERROR(0x0, Status.INTERNAL),
+    PROTOCOL_ERROR(0x1, Status.INTERNAL),
+    INTERNAL_ERROR(0x2, Status.INTERNAL),
+    FLOW_CONTROL_ERROR(0x3, Status.INTERNAL),
+    SETTINGS_TIMEOUT(0x4, Status.INTERNAL),
+    STREAM_CLOSED(0x5, Status.INTERNAL),
+    FRAME_SIZE_ERROR(0x6, Status.INTERNAL),
+    REFUSED_STREAM(0x7, Status.UNAVAILABLE),
+    CANCEL(0x8, Status.CANCELLED),
+    COMPRESSION_ERROR(0x9, Status.INTERNAL),
+    CONNECT_ERROR(0xA, Status.INTERNAL),
+    ENHANCE_YOUR_CALM(0xB, Status.RESOURCE_EXHAUSTED.withDescription("Bandwidth exhausted")),
+    INADEQUATE_SECURITY(0xC, Status.PERMISSION_DENIED.withDescription("Permission denied as "
+        + "protocol is not secure enough to call")),
+    HTTP_1_1_REQUIRED(0xD, Status.UNKNOWN);
+
+    // Populate a mapping of code to enum value for quick look-up.
+    private static final Http2Error[] codeMap;
+    static {
+      Http2Error[] errors = Http2Error.values();
+      int size = (int) errors[errors.length - 1].code() + 1;
+      codeMap = new Http2Error[size];
+      for (Http2Error error : errors) {
+        int index = (int) error.code();
+        codeMap[index] = error;
+      }
+    }
+
+    private final int code;
+    private final Status status;
+
+    private Http2Error(int code, Status status) {
+      this.code = code;
+      this.status = status.augmentDescription("HTTP/2 error code: " + this.name());
+    }
+
+    /**
+     * Gets the code for this error used on the wire.
+     */
+    public long code() {
+      return code;
+    }
+
+    /**
+     * Gets the {@link Status} associated with this HTTP/2 code.
+     */
+    public Status status() {
+      return status;
+    }
+
+    /**
+     * Looks up the HTTP/2 error code enum value for the specified code.
+     *
+     * @param code an HTTP/2 error code value.
+     * @return the HTTP/2 error code enum or {@code null} if not found.
+     */
+    public static Http2Error forCode(long code) {
+      if (code >= codeMap.length || code < 0) {
+        return null;
+      }
+      return codeMap[(int) code];
+    }
+
+    /**
+     * Looks up the {@link Status} from the given HTTP/2 error code.
+     *
+     * @param errorCode the HTTP/2 error code.
+     * @return a {@link Status} representing the given error.
+     */
+    public static Status statusForCode(int code) {
+      Http2Error error = forCode(code);
+      if (error == null) {
+        return Status.UNKNOWN.withDescription("Unrecognized HTTP/2 error: " + code);
+      }
+
+      return error.status();
+    }
+  }
+
   private HttpUtil() {}
 }

netty/src/main/java/io/grpc/transport/netty/NettyClientHandler.java

@@ -31,10 +31,13 @@
 
 package io.grpc.transport.netty;
 
+import static io.netty.util.CharsetUtil.UTF_8;
+
 import com.google.common.base.Preconditions;
 
 import io.grpc.Metadata;
 import io.grpc.Status;
+import io.grpc.transport.HttpUtil;
 import io.netty.buffer.ByteBuf;
 import io.netty.channel.ChannelFuture;
 import io.netty.channel.ChannelFutureListener;
@@ -82,6 +85,7 @@ class NettyClientHandler extends Http2ConnectionHandler {
   private final Deque<PendingStream> pendingStreams = new ArrayDeque<PendingStream>();
   private final Http2LocalFlowController inboundFlow;
   private Throwable connectionError;
+  private Status goAwayStatus;
   private ChannelHandlerContext ctx;
 
   public NettyClientHandler(Http2Connection connection,
@@ -185,6 +189,23 @@ class NettyClientHandler extends Http2ConnectionHandler {
     stream.transportReportStatus(Status.UNKNOWN, false, new Metadata.Trailers());
   }
 
+  private void onGoAwayRead(long errorCode, ByteBuf debugData) {
+    Status status = HttpUtil.Http2Error.statusForCode((int) errorCode);
+    if (debugData.isReadable()) {
+      // If a debug message was provided, use it.
+      String msg = debugData.toString(UTF_8);
+      status = status.withDescription(msg);
+    }
+    goAwayStatus(status);
+  }
+
+  @Override
+  public void close(ChannelHandlerContext ctx, ChannelPromise promise) throws Exception {
+    goAwayStatus(Status.UNAVAILABLE.withDescription("Network channel closed by the client"));
+
+    super.close(ctx, promise);
+  }
+
   /**
    * Handler for the Channel shutting down.
    */
@@ -192,7 +213,7 @@ class NettyClientHandler extends Http2ConnectionHandler {
   public void channelInactive(ChannelHandlerContext ctx) throws Exception {
     try {
       // Fail any streams that are awaiting creation.
-      Status goAwayStatus = goAwayStatus().withDescription("network channel closed");
+      goAwayStatus(goAwayStatus().augmentDescription("Network channel closed"));
       failPendingStreams(goAwayStatus);
 
       // Report status to the application layer for any open streams
@@ -210,6 +231,7 @@ class NettyClientHandler extends Http2ConnectionHandler {
       Http2Exception http2Ex) {
     // Save the error.
     connectionError = cause;
+    goAwayStatus(Status.fromThrowable(connectionError));
 
     super.onConnectionError(ctx, cause, http2Ex);
   }
@@ -317,7 +339,7 @@ class NettyClientHandler extends Http2ConnectionHandler {
    */
   private void createPendingStreams() {
     Http2Connection connection = connection();
-    Http2Connection.Endpoint local = connection.local();
+    Http2Connection.Endpoint<Http2LocalFlowController> local = connection.local();
     Status goAwayStatus = goAwayStatus();
     while (!pendingStreams.isEmpty()) {
       final int streamId = local.nextStreamId();
@@ -362,12 +384,16 @@ class NettyClientHandler extends Http2ConnectionHandler {
    * Returns the appropriate status used to represent the cause for GOAWAY.
    */
   private Status goAwayStatus() {
-    if (connectionError != null) {
+    if (goAwayStatus != null) {
-      return Status.fromThrowable(connectionError);
+      return goAwayStatus;
     }
     return Status.UNAVAILABLE;
   }
 
+  private void goAwayStatus(Status status) {
+    goAwayStatus = goAwayStatus == null ? status : goAwayStatus;
+  }
+
   /**
    * Handles the successful creation of a new stream.
    */
@@ -452,5 +478,11 @@ class NettyClientHandler extends Http2ConnectionHandler {
         throws Http2Exception {
       handler.onRstStreamRead(streamId);
     }
+
+    @Override
+    public void onGoAwayRead(ChannelHandlerContext ctx, int lastStreamId, long errorCode,
+        ByteBuf debugData) throws Http2Exception {
+      handler.onGoAwayRead(errorCode, debugData);
+    }
   }
 }