[mod_proxy] fall back to waiting for connection close if no message length indicator is found in HTTP/1.1 response

It seems this is actually allowed by the RFCs; although it is intended
as HTTP/1.0 backward compatibility, and HTTP/1.1 servers (backends)
really should do better.

Change-Id: I93265bfe7fae57beb10d70d3a4596c5cae7b51bd

src/main/stream_http_response.c

@@ -156,9 +156,15 @@ static void check_response_header(liStreamHttpResponse* shr) {
 		}
 
 		if (!shr->wait_for_close && shr->content_length < 0) {
-			VR_ERROR(shr->vr, "%s", "Backend: need chunked transfer-encoding or content-length for keepalive connections");
-			li_vrequest_error(shr->vr);
-			return;
+			if (LI_HTTP_VERSION_1_1 == shr->parse_response_ctx.http_version) {
+				/* Fallback to waiting for connection close */
+				VR_DEBUG(shr->vr, "%s", "HTTP/1.1 response: no clean message length indicator, fall back to waiting for connection close");
+				shr->wait_for_close = TRUE;
+			} else {
+				VR_ERROR(shr->vr, "%s", "Backend: need chunked transfer-encoding or content-length for keepalive connections");
+				li_vrequest_error(shr->vr);
+				return;
+			}
 		}
 	}
 

tests/t-mod-proxy.py

@@ -41,6 +41,10 @@ class HttpBackendHandler(socketserver.StreamRequestHandler):
 				time.sleep(0.1)
 				self.wfile.write(b"\r\n0\r\n\r\n")
 				continue
+			if reqline[1].startswith("/nolength"):
+				self.wfile.write(b"HTTP/1.1 200 OK\r\n\r\nHello world")
+				self.finish()
+				return
 
 			# send response
 			resp_body = reqline[1].encode('utf-8')
@@ -130,6 +134,15 @@ class TestBackendDelayedChunk(CurlRequest):
 backend_proxy;
 """
 
+class TestBackendNoLength(CurlRequest):
+	URL = "/nolength"
+	EXPECT_RESPONSE_BODY = "Hello world"
+	EXPECT_RESPONSE_CODE = 200
+	no_docroot = True
+	config = """
+backend_proxy;
+"""
+
 class Test(GroupTest):
 	group = [
 		TestSimple,
@@ -138,6 +151,7 @@ class Test(GroupTest):
 		TestBackendForcedKeepalive,
 		TestBackendUpgrade,
 		TestBackendDelayedChunk,
+		TestBackendNoLength,
 	]
 
 	def Prepare(self):