protected abstract void attachSignature()

in src/main/java/com/amazonaws/neptune/auth/NeptuneSigV4SignerBase.java [186:242]
28 lines of code
3 McCabe index (conditional complexity)

    protected abstract void attachSignature(final T nativeRequest, final NeptuneSigV4Signature signature)
            throws NeptuneSigV4SignerException;

    /**
     * Main logics to sign the request. The scheme is to convert the request into a
     * signable request using toSignableRequest, then sign it using the AWS SDK, and
     * finally attach the signature headers to the original request using attachSignature.
     * <p>
     * Note that toSignableRequest and attachSignature are abstract classes in
     * this base class, they require dedicated implementations depending on the type of
     * the native HTTP request.
     *
     * @param request the request to be signed
     * @throws NeptuneSigV4SignerException  in case something goes wrong during signing
     */
    @Override
    public void signRequest(final T request) throws NeptuneSigV4SignerException {

        try {

            // 1. Convert the Apache Http request into an AWS SDK signable request
            //    => to be implemented in subclass
            final SdkHttpFullRequest awsSignableRequest = toSignableRequest(request);

            // 2. Sign the AWS SDK signable request (which internally adds some HTTP headers)
            //    => generic, using the AWS SDK signer
            final AwsCredentials credentials = awsCredentialsProvider.resolveCredentials();
            final Aws4SignerParams awsSignerParams = Aws4SignerParams.builder().
                awsCredentials(credentials).
                signingName(serviceName).
                signingRegion(awsRegion).
                build();
            
            final SdkHttpFullRequest awsSignedRequest = aws4Signer.sign(awsSignableRequest, awsSignerParams);

            // extract session token if temporary credentials are provided
            String sessionToken = "";
            if ((credentials instanceof AwsSessionCredentials)) {
                sessionToken = ((AwsSessionCredentials) credentials).sessionToken();
            }

            final NeptuneSigV4Signature signature =
                    new NeptuneSigV4Signature(
                            awsSignedRequest.matchingHeaders(HOST).get(0),
                            awsSignedRequest.matchingHeaders(X_AMZ_DATE).get(0),
                            awsSignedRequest.matchingHeaders(AUTHORIZATION).get(0),
                            sessionToken);

            // 3. Copy over the Signature V4 headers to the original request
            //    => to be implemented in subclass
            attachSignature(request, signature);

        } catch (final Throwable t) {

            throw new NeptuneSigV4SignerException(t);
        }
    }