[core] fix crash when HTTP backend "Upgrade"s

Change-Id: If7143f49baa2efa8d1fb3f78c6390969730c678e

src/main/stream_http_response.c

@@ -82,6 +82,7 @@ static void check_response_header(liStreamHttpResponse* shr) {
 			li_vrequest_error(shr->vr);
 			return;
 		}
+		shr->wait_for_close = TRUE; /* forward all data until stream closes */
 		shr->response_headers_finished = TRUE;
 		shr->vr->backend_drain->out->is_closed = FALSE;
 		{

tests/t-mod-proxy.py

@@ -30,6 +30,9 @@ class HttpBackendHandler(socketserver.StreamRequestHandler):
 				hdr = hdr.split(':', 2)
 				if hdr[0].lower() == "connection":
 					keepalive = (hdr[1].strip().lower() == "keep-alive")
+			if reqline[1].startswith("/upgrade/custom"):
+				self.wfile.write(b"HTTP/1.1 101 Switching Protocols\r\nConnection: Upgrade\r\nUpgrade: custom\r\n\r\nHello World!")
+				return
 			# send response
 			resp_body = reqline[1].encode('utf-8')
 			clen = "Content-Length: {}\r\n".format(len(resp_body)).encode('utf-8')
@@ -89,7 +92,7 @@ rewrite "/foo(.*)" => "/dest$1";
 backend_proxy;
 """
 
-# backend gets decoded %2F
+# fake a backend forcing keep-alive mode
 class TestBackendForcedKeepalive(CurlRequest):
 	URL = "/keepalive"
 	EXPECT_RESPONSE_BODY = "/keepalive"
@@ -99,12 +102,23 @@ class TestBackendForcedKeepalive(CurlRequest):
 backend_proxy;
 """
 
+# have backend "Upgrade"
+class TestBackendUpgrade(CurlRequest):
+	URL = "/upgrade/custom"
+	EXPECT_RESPONSE_BODY = "Hello World!"
+	EXPECT_RESPONSE_CODE = 101
+	no_docroot = True
+	config = """
+backend_proxy;
+"""
+
 class Test(GroupTest):
 	group = [
 		TestSimple,
 		TestProxiedRewrittenEncodedURL,
 		TestProxiedRewrittenDecodedURL,
 		TestBackendForcedKeepalive,
+		TestBackendUpgrade,
 	]
 
 	def Prepare(self):