protected void attachSignature()

in src/main/java/com/amazonaws/neptune/auth/NeptuneNettyHttpSigV4Signer.java [180:213]
22 lines of code
4 McCabe index (conditional complexity)

    protected void attachSignature(final FullHttpRequest request, final NeptuneSigV4Signature signature)
            throws NeptuneSigV4SignerException {

        // make sure the request is not null and contains the minimal required set of information
        checkNotNull(signature, "The signature must not be null");
        checkNotNull(signature.getHostHeader(), "The signed Host header must not be null");
        checkNotNull(signature.getXAmzDateHeader(), "The signed X-AMZ-DATE header must not be null");
        checkNotNull(signature.getAuthorizationHeader(), "The signed Authorization header must not be null");

        final HttpHeaders headers = request.headers();
        Optional<String> hostHeaderName = Optional.empty();
        // Check if host header is present in the request headers.
        for (String name: headers.names()) {
            if (name.equalsIgnoreCase(HOST)) {
                hostHeaderName = Optional.of(name);
                break;
            }
        }

        // Remove the host header from the request as we are going to add the host header from the signed request.
        // This also ensures that the right header name is used.
        hostHeaderName.ifPresent(name -> headers.remove(name));
        request.headers().add(HOST, signature.getHostHeader());
        request.headers().add(X_AMZ_DATE, signature.getXAmzDateHeader());
        request.headers().add(AUTHORIZATION, signature.getAuthorizationHeader());

        // https://docs.aws.amazon.com/general/latest/gr/sigv4-add-signature-to-request.html
        // For temporary security credentials, it requires an additional HTTP header
        // or query string parameter for the security token. The name of the header
        // or query string parameter is X-Amz-Security-Token, and the value is the session token.
        if (!signature.getSessionToken().isEmpty()) {
            request.headers().add(X_AMZ_SECURITY_TOKEN, signature.getSessionToken());
        }
    }