聊聊dubbo-go的ProviderAuthFilter

type ProviderAuthFilter struct {
}

func init() {
    extension.SetFilter(constant.PROVIDER_AUTH_FILTER, getProviderAuthFilter)
}

func getProviderAuthFilter() filter.Filter {
    return &ProviderAuthFilter{}
}

func (paf *ProviderAuthFilter) Invoke(ctx context.Context, invoker protocol.Invoker, invocation protocol.Invocation) protocol.Result {
    logger.Infof("invoking providerAuth filter.")
    url := invoker.GetUrl()

    err := doAuthWork(&url, func(authenticator filter.Authenticator) error {
        return authenticator.Authenticate(invocation, &url)
    })
    if err != nil {
        logger.Infof("auth the request: %v occur exception, cause: %s", invocation, err.Error())
        return &protocol.RPCResult{
            Err: err,
        }
    }

    return invoker.Invoke(ctx, invocation)
}

func (paf *ProviderAuthFilter) OnResponse(ctx context.Context, result protocol.Result, invoker protocol.Invoker, invocation protocol.Invocation) protocol.Result {
    return result
}

func doAuthWork(url *common.URL, do func(filter.Authenticator) error) error {

    shouldAuth := url.GetParamBool(constant.SERVICE_AUTH_KEY, false)
    if shouldAuth {
        authenticator := extension.GetAuthenticator(url.GetParam(constant.AUTHENTICATOR_KEY, constant.DEFAULT_AUTHENTICATOR))
        return do(authenticator)
    }
    return nil
}

func (authenticator *DefaultAuthenticator) Authenticate(invocation protocol.Invocation, url *common.URL) error {
    accessKeyId := invocation.AttachmentsByKey(constant.AK_KEY, "")

    requestTimestamp := invocation.AttachmentsByKey(constant.REQUEST_TIMESTAMP_KEY, "")
    originSignature := invocation.AttachmentsByKey(constant.REQUEST_SIGNATURE_KEY, "")
    consumer := invocation.AttachmentsByKey(constant.CONSUMER, "")
    if IsEmpty(accessKeyId, false) || IsEmpty(consumer, false) ||
        IsEmpty(requestTimestamp, false) || IsEmpty(originSignature, false) {
        return errors.New("failed to authenticate your ak/sk, maybe the consumer has not enabled the auth")
    }

    accessKeyPair, err := getAccessKeyPair(invocation, url)
    if err != nil {
        return errors.New("failed to authenticate , can't load the accessKeyPair")
    }

    computeSignature, err := getSignature(url, invocation, accessKeyPair.SecretKey, requestTimestamp)
    if err != nil {
        return err
    }
    if success := computeSignature == originSignature; !success {
        return errors.New("failed to authenticate, signature is not correct")
    }
    return nil
}