Specification out of date?

[Ricardo Newbery]

On Mar 20, 2008, at 2:15 AM, Dag-Erling Smørgrav wrote:

> Ricardo Newbery <ric at digitalmarbles.com> writes:
>> [...]
>
> Yes, the spec is two years out of date.


Right.  That much was apparent.  My question again is shouldn't this  
document be updated?  And is there still an intent to implement any of  
this?


> If you want Varnish to obey Cache-Control, it is trivial to  
> implement in
> VCL.


Well... perhaps.

I think I can implement 'no-cache' and 'private' with the following  
stanza in vcl_fetch:

     if (obj.http.Cache-Control ~ "(no-cache|private)") {
         pass;
     }

But this behavior is trivial to duplicate in Varnish with just s- 
maxage=0 so there is probably no advantage to this unless my backend  
can't set s-maxage for some reason.

I'm actually more interested in trying to reproduce the semantics of  
the 'public' token.  But I'm having trouble figuring out how to  
implement this one in vcl.  In the default vcl, authenticated requests  
are passed through before any cache check or backend fetch is  
attempted.  If I rearrange this a bit so that the authenticate test  
comes later, I think I run into a vcl limitation.

For example, the following seems like it should work:

1) Remove from vcl_recv the following...

              if (req.http.Authenticate || req.http.Cookie) {
                  pass;
              }

2) Add to vcl_hit the following (after the !obj.cacheable test)...

              if (obj.http.Cache-Control ~ "public" ) {
                  deliver;
              }
              if (req.http.Authenticate) {
                  fetch;
              }

3) Add to vcl_fetch the following (after the other tests)...

              if (obj.http.Cache-Control ~ "public" ) {
                  insert;
              }
              if (req.http.Authenticate) {
                  pass;
              }

But the vcl man page appears to tell me that 'fetch' is not a valid  
keyword in vcl_hit so, if I believe the docs, then this is not going  
to work.

Do you have any suggestions on how to implement the 'public' token in  
vcl?

Ric