https://medium.com/canopas/golang-handling-appstore-server-to-server-v2-notifications-ef1e8eb05118 - app_store_final

app_store-final.go

func parseJwtSignedData(tokenStr string) error {

	rootCertStr, err := extractHeaderByIndex(tokenStr, 2) // get root cert from X5c header
	if err != nil {
		return err
	}

	intermediateCertStr, err := extractHeaderByIndex(tokenStr, 1) // get intermediate cert from X5c header
	if err != nil {
		return err
	}

	/** verify certs. if not verified, return err **/
	if err = verifyCert(rootCertStr, intermediateCertStr); err != nil {  
		return err
	}

	/** payload data **/
	payload := &NotificationPayload{}

	_, err = jwt.ParseWithClaims(tokenStr, payload, func(token *jwt.Token) (interface{}, error) {
		return extractPublicKeyFromToken(tokenStr)
	})


	/** transaction info **/
	transactionInfo := &TransactionInfo{}
	tokenStr = payload.Data.SignedTransactionInfo

	_, err = jwt.ParseWithClaims(tokenStr, transactionInfo, func(token *jwt.Token) (interface{}, error) {
		return extractPublicKeyFromToken(tokenStr)
	})


	/** renewal info **/
	renewalInfo := &RenewalInfo{}
	tokenStr = payload.Data.SignedRenewalInfo

	_, err = jwt.ParseWithClaims(tokenStr, renewalInfo, func(token *jwt.Token) (interface{}, error) {
		return extractPublicKeyFromToken(tokenStr)
	})

	return nil
}