From 60d3e7c5362a739f6795a2a87fc86a62059de501 Mon Sep 17 00:00:00 2001
From: Eric Anderson <ejona@google.com>
Date: Thu, 10 Dec 2020 14:54:33 -0800
Subject: [PATCH] core: On unexpected EOS, mention whether the frame was empty

Empty DATA frames with EOS tell a stronger tale as to where the server
may have its bug.
---
 .../grpc/internal/Http2ClientStreamTransportState.java | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/core/src/main/java/io/grpc/internal/Http2ClientStreamTransportState.java b/core/src/main/java/io/grpc/internal/Http2ClientStreamTransportState.java
index da9f7bc5d1d..c2bcb350a9f 100644
--- a/core/src/main/java/io/grpc/internal/Http2ClientStreamTransportState.java
+++ b/core/src/main/java/io/grpc/internal/Http2ClientStreamTransportState.java
@@ -144,11 +144,17 @@ protected void transportDataReceived(ReadableBuffer frame, boolean endOfStream)
             new Metadata());
         return;
       }
+      int frameSize = frame.readableBytes();
       inboundDataReceived(frame);
       if (endOfStream) {
         // This is a protocol violation as we expect to receive trailers.
-        transportError =
-            Status.INTERNAL.withDescription("Received unexpected EOS on DATA frame from server.");
+        if (frameSize > 0) {
+          transportError = Status.INTERNAL
+              .withDescription("Received unexpected EOS on non-empty DATA frame from server");
+        } else {
+          transportError = Status.INTERNAL
+              .withDescription("Received unexpected EOS on empty DATA frame from server");
+        }
         transportErrorMetadata = new Metadata();
         transportReportStatus(transportError, false, transportErrorMetadata);
       }