[6.0] f12d4c026 h2: Move the frame completion check up

[Dridi Boukelmoune]

commit f12d4c0266a6b499d2936c03fcaeb030aa1158a4
Author: Dag Haavi Finstad <daghf at varnish-software.com>
Date:   Mon May 28 11:14:59 2018 +0200

    h2: Move the frame completion check up
    
    Avoid failing sessions with pipelined data.

diff --git a/bin/varnishd/http2/cache_http2_proto.c b/bin/varnishd/http2/cache_http2_proto.c
index 1da101a0e..1bba9b332 100644
--- a/bin/varnishd/http2/cache_http2_proto.c
+++ b/bin/varnishd/http2/cache_http2_proto.c
@@ -830,11 +830,12 @@ h2_frame_complete(struct http_conn *htc)
 	if (l < 9)
 		return (HTC_S_MORE);
 	u = vbe32dec(htc->rxbuf_b) >> 8;
-	if (l > h2->local_settings.max_frame_size + 9)
+	if (l >= u + 9)
+		return (HTC_S_COMPLETE);
+	else if (l > h2->local_settings.max_frame_size + 9)
 		return (HTC_S_OVERFLOW);
-	if (l < u + 9)	// XXX: Only for !DATA frames
-		return (HTC_S_MORE);
-	return (HTC_S_COMPLETE);
+
+	return (HTC_S_MORE);
 }
 
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