Hello, I noticed a change in behavior when going from Apache/2.4.16 to Apache/2.4.33 when sending a 204 Response that the header Content-Length 0 is removed by Apache when it is included in 204 Response.
This looks to be the correct behavior based on the RFC spec https://tools.ietf.org/html/rfc7230#section-3.3.2 “A server MUST NOT send a Content-Length header field in any response with a status code of 1xx (Informational) or 204 (No Content).” However, what I am also noticing is a delay in the 204 Response being sent to the client in Apache/2.4.33. The use case is that this is a PHP script on the server that is sending the 204 Response immediately and the continuing to do work. In Apache/2.4.16 the 204 Response is sent immediately, in Apache/2.4.33 the response is sent only after the PHP script exits. My best guess is that the stripping of the Content-Length 0 header is causing Apache to not flush the socket right away, but it now waits for the PHP script to exit. If I send a 200 Response instead, with a Content-Length 0, then there is no delay in Apache/2.4.33 I checked the bugs database and couldn't find anything, so am checking here to see if it is maybe an apache bug. I confirmed the issue still exists in Apache/2.4.41. Below are my steps to test and the results. Thanks, Todd https://github.com/docker-library/php/tree/master/7.4/buster/apache changed debian:buster-slim to debian:unstable-slim to get latest apache docker build -t php-docker-apache-example . docker run -d -p 8080:80 php-docker-apache-example First experiment, returning 204 php.index <?php header("HTTP/1.1 204 No Content"); ob_end_clean(); header('Connection: close'); ob_start(); $size = ob_get_length(); header("Content-Length: $size"); ob_end_flush(); flush(); sleep(5); exit; ?> ~/php-docker-apache-example $ time curl -v http://127.0.0.1:8080 * Rebuilt URL to: http://127.0.0.1:8080/ * Trying 127.0.0.1... * TCP_NODELAY set * Connected to 127.0.0.1 (127.0.0.1) port 8080 (#0) > GET / HTTP/1.1 > Host: 127.0.0.1:8080 > User-Agent: curl/7.54.0 > Accept: */* > < HTTP/1.1 204 No Content < Date: Thu, 06 Feb 2020 14:22:36 GMT < Server: Apache/2.4.41 (Debian) < X-Powered-By: PHP/7.4.2 < Connection: close < * Closing connection 0 real 0m5.020s user 0m0.005s sys 0m0.007s and the apache logs for that are $ docker logs --follow 62046b36868209242de8cf681f0711f811a86ffa5adf66c31865928204acdbe9 AH00558: apache2: Could not reliably determine the server's fully qualified domain name, using 172.17.0.2. Set the 'ServerName' directive globally to suppress this message AH00558: apache2: Could not reliably determine the server's fully qualified domain name, using 172.17.0.2. Set the 'ServerName' directive globally to suppress this message [Thu Feb 06 14:37:27.367142 2020] [mpm_prefork:notice] [pid 1] AH00163: Apache/2.4.41 (Debian) PHP/7.4.2 configured -- resuming normal operations [Thu Feb 06 14:37:27.367234 2020] [core:notice] [pid 1] AH00094: Command line: 'apache2 -D FOREGROUND' 172.17.0.1 - - [06/Feb/2020:14:37:59 +0000] "GET / HTTP/1.1" 204 140 "-" "curl/7.54.0" Second experiment, returning 200 Response index.php <?php header("HTTP/1.1 200 OK"); ob_end_clean(); header('Connection: close'); ob_start(); $size = ob_get_length(); header("Content-Length: $size"); ob_end_flush(); flush(); sleep(5); exit; ?> ~/php-docker-apache-example $ time curl -v http://127.0.0.1:8080 * Rebuilt URL to: http://127.0.0.1:8080/ * Trying 127.0.0.1... * TCP_NODELAY set * Connected to 127.0.0.1 (127.0.0.1) port 8080 (#0) > GET / HTTP/1.1 > Host: 127.0.0.1:8080 > User-Agent: curl/7.54.0 > Accept: */* > < HTTP/1.1 200 OK < Date: Thu, 06 Feb 2020 14:26:29 GMT < Server: Apache/2.4.41 (Debian) < X-Powered-By: PHP/7.4.2 < Connection: close < Content-Length: 0 < Vary: Accept-Encoding < Content-Type: text/html; charset=UTF-8 < * Closing connection 0 real 0m0.026s user 0m0.005s sys 0m0.008s --------------------------------------------------------------------- To unsubscribe, e-mail: users-unsubscr...@httpd.apache.org For additional commands, e-mail: users-h...@httpd.apache.org
