Using the rest module

[Nick Porter]

On 16/11/2024 18:06, Francis Augusto Medeiros-Logeay via 
Freeradius-Users wrote:
> In my case, I need simply to evaluate a value of a nested json key that doesn’t really match any existing attributes.

When called as a module, in FreeRADIUS v3, rest module only handles a 
limited number of formats of return JSON, intended for populating 
attributes with data retrieved from the REST endpoint.

If your returned JSON is relatively small and consistent in format you 
may be able to do what you want by using the %{rest: } xlat and then 
doing a regex match on the returned string - that would need some 
experimentation.e.g.

update { &control:Tmp-String-1 := "%{rest: <URL>}" }

if (&control.Tmp-String-1 =~ /<regex to extract match from JSON>/) { ... }

> I saw that there is a json module that might be used with the rest, but it doesn’t seem to be available for the version I am using (3.0.21 on RHEL 9).

The JSON module in FreeRADIUS 3.2 is only a helper for encoding - 
intended for converting attribute lists to JSON for sending to log 
destinations or as body data for POST requests.

3.0.21 is also pretty old - 3.2.6 is the current stable release - 
available as packages from https://packages.networkradius.com/

> I have three api calls, to three different url’s, so I figured out how to create multiple instances of the rest module, which is great. It’s just the response logic that I’m failing to understand.

If the xlat approach works, you would only need one module instance 
since the URL is built in the xlat call.


Really the functionality you want is all in the up-coming FreeRADIUS v4 
- that can extract arbitrary components from JSON. Whether v4 will work 
for you depends on the precise features you require - there are still a 
few gaps being worked on.

Nick

-- 
Nick Porter