VCL: returning early from a custom function

[Cosimo Streppone]

On Wed, Apr 11, 2018, at 16:43, Anheyer, Tom wrote:
> What about:
> 
> sub rate_limit {
> 
>         if (req.url ~ "pattern1") {
>            std.log("pattern1 requests must never be throttled");
>         }
>         else {
>             if (req.url ~ "pattern2") {
>                 if (vsthrottle.is_denied("pattern2" + client.identity,
> 100, 10s)) {
>                     std.log("pattern2 throttling for ip " +
> client.identity);
>                     return(synth(429, "ETOOMANYREQUESTS"));
>                 }
>             }
> 
>             if (vsthrottle.is_denied("ip:" + client.identity, 500, 10s)) {
>                 std.log("global throttling for ip " + client.identity);
>                 return(synth(429, "ETOOMANYREQUESTS"));
>             }
>         }
> 
>     }

Yes, that's one of the alternatives, though the "whitelisted" patterns
are more than just one.

I ended up doing something like:

   set req.http.Rate-Limit = "1";
   
   if (whitelisted-pattern1) { set req.http.Rate-Limit = "0"; }
   if (whitelisted-pattern2) { set req.http.Rate-Limit = "0"; }
   ...

   if (req.http.Rate-Limit == "0") {
       # no rate limiting
   } else {
       # yes, do rate limit
   }

I intend to look at vmod_var to see if I can make this prettier.

-- 
Cosimo