Bug report: Bad Last-Modified HTTP header

  • Unknown's avatar
    puzzlement · Member ·

    I’m using a script to fetch this Atom feed:

    https://frameshiftconsulting.com/blog/feed/atom/

    which is on a site hosted by WordPress.com.

    The HTTP headers for this feed have an incorrect value:

    Last-Modified: GMT

    According to the specification of the Last-Modified header [1] this header value should not be a bare ‘GMT’, it should should be of the form HTTP-Date [2] which would look something like:

    Last-Modified: Tue, 15 Nov 1994 12:45:26 GMT

    [1] https://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.29
    [2] https://www.w3.org/Protocols/rfc2616/rfc2616-sec3.html#sec3.3.1

    The blog I need help with is: (visible only to logged in users)

  • supernovia · Staff ·

    Thanks Mary, it looks like WordPress.org core set this format a while back:
    https://core.trac.wordpress.org/ticket/983

    I’m digging around on this side, but if you’re up to it, you can file a patch, too.

  • Unknown's avatar
    puzzlement · Member ·

    Thanks, but that WordPress.org bug seems to describe something different: a bug in the dates within the Atom feed itself. The bug I am describing in is an HTTP header: in the server-client communication conversation, not in the contents of the Atom feed.

    It’s possible this is set by WordPress software (as PHP can modify HTTP headers) but it’s more likely to be an webserver (eg nginx) configuration error of some kind.

    Here’s a bit more detail

    $ HEAD https://frameshiftconsulting.com/blog/feed/
    200 OK
    Connection: close
    Date: Mon, 29 Aug 2016 22:30:11 GMT
    ETag: “99b889a9cd748e8b4eca0eb3758d138d”
    Server: nginx
    Vary: Accept-Encoding
    Vary: Cookie
    Content-Type: application/rss+xml; charset=UTF-8
    Last-Modified: GMT
    Client-Date: Mon, 29 Aug 2016 22:30:11 GMT
    Client-Peer: 192.0.78.24:443
    Client-Response-Num: 1
    Client-SSL-Cert-Issuer: /C=US/O=Let’s Encrypt/CN=Let’s Encrypt Authority X3
    Client-SSL-Cert-Subject: /CN=tls.automattic.com
    Client-SSL-Cipher: ECDHE-RSA-AES128-GCM-SHA256
    Client-SSL-Socket-Class: IO::Socket::SSL
    Strict-Transport-Security: max-age=86400
    X-Ac: 2.syd _bur
    X-Hacker: If you’re reading this, you should visit automattic.com/jobs and apply to join the fun, mention this header.

    $ HEAD https://frameshiftconsulting.com/blog/feed/atom/
    200 OK
    Connection: close
    Date: Mon, 29 Aug 2016 22:30:02 GMT
    ETag: “99b889a9cd748e8b4eca0eb3758d138d”
    Server: nginx
    Vary: Accept-Encoding
    Vary: Cookie
    Content-Type: application/atom+xml; charset=UTF-8
    Last-Modified: GMT
    Client-Date: Mon, 29 Aug 2016 22:30:02 GMT
    Client-Peer: 192.0.78.24:443
    Client-Response-Num: 1
    Client-SSL-Cert-Issuer: /C=US/O=Let’s Encrypt/CN=Let’s Encrypt Authority X3
    Client-SSL-Cert-Subject: /CN=tls.automattic.com
    Client-SSL-Cipher: ECDHE-RSA-AES128-GCM-SHA256
    Client-SSL-Socket-Class: IO::Socket::SSL
    Strict-Transport-Security: max-age=86400
    X-Ac: 2.syd _bur
    X-Hacker: If you’re reading this, you should visit automattic.com/jobs and apply to join the fun, mention this header.

  • supernovia · Staff ·

    Oh, right, the http headers. Alright, I’ll be looking for details on that as well.

  • supernovia · Staff ·

    For what it’s worth, these return proper Last Modified stamps:

    https://frameshiftconsulting.com/tag/classes/feed/atom

    https://frameshiftconsulting.com/feed/atom

    So I don’t think it’s a server misconfiguration. Still trying to figure out why /blog/feed/atom is off.

  • supernovia · Staff ·

    Hi @Mary, our developers have done a bit of digging on this. It seems two factors go into this bug:

    – your posts page <strike>( /blog) is</strike> was not the main page of the site
    – your posts don’t have any comments (they are disabled)

    So we’ve noted that issue and have it on our to do list. But in the meantime, all of your posts will still show here with the proper stamp, so we recommend using this feed instead:
    https://frameshiftconsulting.com/feed/atom

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