add decode utils for response body v2 of app store

[takecy]

• refs server notification responseBodyV2 #149

[thilonel]

@takecy I was trying to figure this out, here's a gist of where I am: https://gist.github.com/thilonel/7b7285b9bad211cc88a1b8ccfdbe9e0e

What do you think?

[takecy]

Thanks! Looks like a good example 👀
If the tokenString in the gist is the following, it should work.
https://developer.apple.com/documentation/appstoreservernotifications/responsebodyv2

I have used this package which is very similar.
https://github.com/dgrijalva/jwt-go

This package made by squre also seems to be used a lot.
https://github.com/square/go-jose

[thilonel]

@takecy tokenString is the value of signedPayload. What I'm mostly worried about here, is if verifying the signature of the signing cert by the intermediate is enough or not.

The about section of https://github.com/dgrijalva/jwt-go links to golang-jwt, which I've used. It's practically the same, just got cloned to a community maintained repo.

I also checked go-jose, but ended up with this. 🤷‍♂️

Will you integrate this functionality into go-iap or do you want me to fork and PR? I'd say with the help of the gist, you're gonna be way faster by yourself :) No forth and back on anything :)

[RealLau]

any update bro?
I also found an example that uses Python, but I don't know how to convert it to golang:
here

[richzw]

@RealLau , I try to add the method ParseNotificationV2 to parse the notification v2 body. You could try it.

[Daydaylw3]

@richzw hi, thx for your method. But could you give me an example about how to decode SignedRenewalInfo and SignedTransactionInfo field?

[richzw]

@Daydaylw3

Here is one sample code to use ParseNotificationV2 to decode SignedRenewalInfo and SignedTransactionInfo field

      tokenStr := SignedRenewalInfo // or SignedTransactionInfo
      if err := c.ParseNotificationV2(tokenStr, result); err != nil {
      }

      if !result.Valid {
      }

      claims := result.Claims.(jwt.MapClaims)
      for key, val := range claims {
        fmt.Printf("Key: %v, value: %v\n", key, val) // key value of SignedRenewalInfo
      }