Patch from upstream

commit dbcbae227b757043651ee1e7d1cc729727f94c8d
Author: Poul-Henning Kamp <phk@FreeBSD.org>
Date:   Wed Sep 21 06:22:55 2016 +0000

    Do not insist the H2 connection preface arrives in a single packet.
    
    Fixes: #2094
    Fixes: #2096

diff --git a/bin/varnishd/http1/cache_http1_proto.c b/bin/varnishd/http1/cache_http1_proto.c
index b5273c6..e788ed6 100644
--- a/bin/varnishd/http1/cache_http1_proto.c
+++ b/bin/varnishd/http1/cache_http1_proto.c
@@ -46,6 +46,8 @@
 #include "config.h"
 
 #include "cache/cache.h"
+#include "cache/cache_transport.h"
+
 #include "cache_http1.h"
 
 #include "vct.h"
@@ -66,6 +68,7 @@ enum htc_status_e __match_proto__(htc_complete_f)
 HTTP1_Complete(struct http_conn *htc)
 {
 	char *p;
+	enum htc_status_e retval;
 
 	CHECK_OBJ_NOTNULL(htc, HTTP_CONN_MAGIC);
 
@@ -78,6 +81,11 @@ HTTP1_Complete(struct http_conn *htc)
 	if (p == htc->rxbuf_e)
 		return (HTC_S_EMPTY);
 
+	/* Do not return a partial H2 connection preface */
+	retval = H2_prism_complete(htc);
+	if (retval != HTC_S_JUNK)
+		return (retval);
+
 	/*
 	 * Here we just look for NL[CR]NL to see that reception
 	 * is completed.  More stringent validation happens later.
diff --git a/bin/varnishd/http2/cache_http2_proto.c b/bin/varnishd/http2/cache_http2_proto.c
index 73d0c95..54b8a2e 100644
--- a/bin/varnishd/http2/cache_http2_proto.c
+++ b/bin/varnishd/http2/cache_http2_proto.c
@@ -474,10 +474,11 @@ H2_prism_complete(struct http_conn *htc)
 
 	CHECK_OBJ_NOTNULL(htc, HTTP_CONN_MAGIC);
 	l = htc->rxbuf_e - htc->rxbuf_b;
-	if (l < strlen(H2_prism))
-		return (HTC_S_MORE);
-	if (!memcmp(htc->rxbuf_b, H2_prism, sizeof(H2_prism)))
+	if (l >= sizeof(H2_prism) &&
+	    !memcmp(htc->rxbuf_b, H2_prism, sizeof(H2_prism)))
 		return (HTC_S_COMPLETE);
+	if (l < sizeof(H2_prism) && !memcmp(htc->rxbuf_b, H2_prism, l))
+		return (HTC_S_MORE);
 	return (HTC_S_JUNK);
 }