http/request: Only use absolute form in http < 2

http/request.lua

@@ -451,17 +451,29 @@ function request_methods:go(timeout)
 				if request_headers:get(":method") == "CONNECT" then
 					error("cannot use HTTP Proxy with CONNECT method")
 				end
-				-- TODO: Check if :path already has authority?
-				local old_url = self:to_uri(false)
 				host = assert(proxy.host, "proxy is missing host")
 				port = proxy.port or http_util.scheme_to_port[proxy.scheme]
-				-- proxy requests get a uri that includes host as their path
-				if not cloned_headers then
-					request_headers = request_headers:clone()
-					cloned_headers = true -- luacheck: ignore 311
+				-- TODO: figure out what :path should be when using a http2 proxy
+				if version ~= 2 then
+					-- for now, just force 1.1
+					version = 1.1
+					-- RFC 7230 Section 5.3.2
+					-- When making a request to a proxy, other than a CONNECT or server-wide
+					-- OPTIONS request (as detailed below), a client MUST send the target
+					-- URI in absolute-form as the request-target.
+					-- TODO: Check if :path already has authority?
+					local old_url = self:to_uri(false)
+					if not cloned_headers then
+						request_headers = request_headers:clone()
+						cloned_headers = true
+					end
+					request_headers:upsert(":path", old_url)
 				end
-				request_headers:upsert(":path", old_url)
 				if proxy.userinfo then
+					if not cloned_headers then
+						request_headers = request_headers:clone()
+						cloned_headers = true -- luacheck: ignore 311
+					end
 					request_headers:upsert("proxy-authorization", "basic " .. basexx.to_base64(proxy.userinfo), true)
 				end
 			end