Fix outputting Content-Length and Transfer-Encoding headers on HEAD r…

…equests for Ruby apps

CHANGELOG

@@ -2,6 +2,7 @@ Release 5.0.26
 --------------
 
  * `passenger-status --show=server` now reports the speed at which new requests are accepted.
+ * Fixes outputting Content-Length and Transfer-Encoding headers on HEAD requests for Ruby apps. These headers were omitted in previous versions on HEAD requests.
  * [Nginx] Passenger can now be [compiled as an Nginx dynamic module](https://www.phusionpassenger.com/library/install/nginx/install_as_nginx_module.html#dynamic-module). Thanks to Ruslan Ermilov from NGINX Inc for contributing this.
  * [Standalone] Prints a warning when an unsupported configuration option in Passengerfile.json is set.
  * [Enterprise] The rolling restart feature now waits until the old process is completely gone (drained its request queue, process exited) before proceeding with rolling restarting the next process. This results in friendlier resource usage during rolling restart.

src/agent/Core/Controller/ForwardResponse.cpp

@@ -1,6 +1,6 @@
 /*
  *  Phusion Passenger - https://www.phusionpassenger.com/
- *  Copyright (c) 2011-2015 Phusion Holding B.V.
+ *  Copyright (c) 2011-2016 Phusion Holding B.V.
  *
  *  "Passenger", "Phusion Passenger" and "Union Station" are registered
  *  trademarks of Phusion Holding B.V.
@@ -295,6 +295,7 @@ Controller::onAppSourceData(Client *client, Request *req, const MemoryKit::mbuf
 			// EOF
 			UPDATE_TRACE_POINT();
 			SKC_TRACE(client, 2, "Application sent EOF");
+			SKC_TRACE(client, 2, "Not keep-aliving application session connection");
 			req->session->close(true, false);
 			endRequest(&client, &req);
 			return Channel::Result(0, false);
@@ -1078,6 +1079,10 @@ Controller::handleAppResponseBodyEnd(Client *client, Request *req) {
 
 OXT_FORCE_INLINE void
 Controller::keepAliveAppConnection(Client *client, Request *req) {
+	SKC_TRACE(client, 2,
+		((req->appResponse.wantKeepAlive)
+		? "Keep-aliving application session connection"
+		: "Not keep-aliving application session connection"));
 	req->session->close(true, req->appResponse.wantKeepAlive);
 }
 

src/ruby_supportlib/phusion_passenger/rack/thread_handler_extension.rb

@@ -1,6 +1,6 @@
 # encoding: binary
 #  Phusion Passenger - https://www.phusionpassenger.com/
-#  Copyright (c) 2010-2015 Phusion Holding B.V.
+#  Copyright (c) 2010-2016 Phusion Holding B.V.
 #
 #  "Passenger", "Phusion Passenger" and "Union Station" are registered
 #  trademarks of Phusion Holding B.V.
@@ -215,7 +215,7 @@ def process_body(env, connection, socket_wrapper, status, is_head_request, heade
             if !body.is_a?(Array) || headers.has_key?(X_SENDFILE_HEADER) ||
                headers.has_key?(X_ACCEL_REDIRECT_HEADER)
               # If X-Sendfile or X-Accel-Redirect is set, don't check the
-              # body size. PassengerAgent's RequestHandler will ignore the
+              # body size. Passenger's Core Controller will ignore the
               # body anyway. See
               # ServerKit::HttpHeaderParser::processParseResult(const HttpParseResponse &)
               @can_keepalive = false
@@ -241,7 +241,10 @@ def process_body(env, connection, socket_wrapper, status, is_head_request, heade
             # Disallowed by the HTTP spec
             raise "Response object may not contain both Content-Length and Transfer-Encoding"
           end
-        elsif output_body
+        elsif status_code_allows_body?(status)
+          # This is a response for which a body is allowed, although the request
+          # may be one which does not expect a body (HEAD requests).
+          #
           # The app has set neither the Content-Length nor the Transfer-Encoding
           # header. This means we'll have to add one of those headers. We know exactly how
           # big our body will be, so we can keep-alive the connection.
@@ -270,37 +273,33 @@ def process_body(env, connection, socket_wrapper, status, is_head_request, heade
         # If this is a request without body, write out headers without body.
         if !output_body
           connection.writev(headers_output)
-          signal_keep_alive_allowed!
-          return
-        end
-
-        # Otherwise, write out headers and body, then verify at the end whether what
-        # we wrote is matches the message length. Only keep-alive connection if it
-        # is the case.
-        case message_length_type
-        when :content_length
-          if body.is_a?(Array)
-            connection.writev2(headers_output, body)
-          else
+        else
+          # Otherwise, write out headers and body.
+          case message_length_type
+          when :content_length
+            if body.is_a?(Array)
+              connection.writev2(headers_output, body)
+            else
+              connection.writev(headers_output)
+              body.each do |part|
+                connection.write(part.to_s)
+              end
+            end
+          when :chunked_by_app
             connection.writev(headers_output)
             body.each do |part|
               connection.write(part.to_s)
             end
-          end
-        when :chunked_by_app
-          connection.writev(headers_output)
-          body.each do |part|
-            connection.write(part.to_s)
-          end
-        when :needs_chunking
-          connection.writev(headers_output)
-          body.each do |part|
-            size = bytesize(part.to_s)
-            if size != 0
-              connection.writev(chunk_data(part.to_s, size))
+          when :needs_chunking
+            connection.writev(headers_output)
+            body.each do |part|
+              size = bytesize(part.to_s)
+              if size != 0
+                connection.writev(chunk_data(part.to_s, size))
+              end
             end
+            connection.write(TERMINATION_CHUNK)
           end
-          connection.write(TERMINATION_CHUNK)
         end
 
         signal_keep_alive_allowed!
@@ -360,10 +359,12 @@ def lookup_header(haystack, needles)
         nil
       end
 
+      def status_code_allows_body?(status)
+        status < 100 || (status >= 200 && status != 204 && status != 304)
+      end
+
       def should_output_body?(status, is_head_request)
-        return (status < 100 ||
-          (status >= 200 && status != 204 && status != 304)) &&
-          !is_head_request
+        status_code_allows_body?(status) && !is_head_request
       end
 
       def chunk_data(data, size)