From 7206c860ec5503a54f42adc5305440647739c515 Mon Sep 17 00:00:00 2001
From: mpl <mathieu.lonjaret@gmail.com>
Date: Sat, 4 Feb 2017 18:16:17 +0100
Subject: [PATCH] Catch and report non HTTP/2 error case

---
 call.go | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/call.go b/call.go
index aa2f7bd..b224caf 100644
--- a/call.go
+++ b/call.go
@@ -199,6 +199,9 @@ func (cc *ClientConn) invoke(ctx context.Context, method string, args, reply int
 	}
 	defer res.Body.Close()
 
+	if !res.ProtoAtLeast(2, 0) {
+		return Errorf(codes.Internal, "grpc: HTTP/2 required; response was %v", res.Proto)
+	}
 	if res.StatusCode != 200 {
 		return Errorf(codes.Internal, "grpc: unexpected status code %v", res.Status)
 	}