protected void onConnectRequest()

in sdk/greengrass/event-stream-rpc-server/src/main/java/software/amazon/awssdk/eventstreamrpc/ServiceOperationMappingContinuationHandler.java [71:142]
61 lines of code
14 McCabe index (conditional complexity)

    protected void onConnectRequest(List<Header> headers, byte[] payload) {
        final int[] responseMessageFlag = { 0 };
        final MessageType acceptResponseType = MessageType.ConnectAck;

        final AuthenticationHandler authentication = serviceHandler.getAuthenticationHandler();
        final AuthorizationHandler authorization = serviceHandler.getAuthorizationHandler();

        try {
            final Optional<String> versionHeader = headers.stream()
                    .filter(header -> header.getHeaderType() == HeaderType.String
                            && header.getName().equals(EventStreamRPCServiceModel.VERSION_HEADER))
                    .map(header -> header.getValueAsString())
                    .findFirst();
            if (versionHeader.isPresent() &&
                    Version.fromString(versionHeader.get()).equals(Version.getInstance())) {
                //version matches
                if (authentication == null) {
                    throw new IllegalStateException(
                            String.format("%s has null authentication handler!", serviceHandler.getServiceName()));
                }
                if (authorization == null) {
                    throw new IllegalStateException(
                            String.format("%s has null authorization handler!", serviceHandler.getServiceName()));
                }

                LOGGER.trace(String.format("%s running authentication handler", serviceHandler.getServiceName()));
                authenticationData = authentication.apply(headers, payload);
                if (authenticationData == null) {
                    throw new IllegalStateException(String.format("%s authentication handler returned null", serviceHandler.getServiceName()));
                }
                LOGGER.info(String.format("%s authenticated identity: %s", serviceHandler.getServiceName(), authenticationData.getIdentityLabel()));

                final Authorization authorizationDecision = authorization.apply(authenticationData);
                switch (authorizationDecision) {
                    case ACCEPT:
                        LOGGER.info("Connection accepted for " + authenticationData.getIdentityLabel());
                        responseMessageFlag[0] = MessageFlags.ConnectionAccepted.getByteValue();
                        break;
                    case REJECT:
                        LOGGER.info("Connection rejected for: " + authenticationData.getIdentityLabel());
                        break;
                    default:
                        //got a big problem if this is the outcome. Someone forgot to update this switch-case
                        throw new RuntimeException("Unknown authorization decision for " + authenticationData.getIdentityLabel());
                }
            } else { //version mismatch
                LOGGER.warn(String.format("Client version {%s} mismatches server version {%s}",
                        versionHeader.isPresent() ? versionHeader.get() : "null",
                        Version.getInstance().getVersionString()));
            }
        } catch (Exception e) {
            LOGGER.error(String.format("%s occurred while attempting to authN/authZ connect: %s", e.getClass(), e.getMessage()), e);
        } finally {
            final String authLabel =  authenticationData != null ? authenticationData.getIdentityLabel() : "null";
            LOGGER.info("Sending connect response for " + authLabel);
            connection.sendProtocolMessage(null, null, acceptResponseType, responseMessageFlag[0])
                .whenComplete((res, ex) -> {
                    //TODO: removing log statements due to known issue of locking up
                    if (ex != null) {
                        //LOGGER.severe(String.format("Sending connection response for %s threw exception (%s): %s",
                        //   authLabel, ex.getClass().getCanonicalName(), ex.getMessage()));
                    }
                    else {
                        //LOGGER.info("Successfully sent connection response for: " + authLabel);
                    }
                    if (responseMessageFlag[0] != MessageFlags.ConnectionAccepted.getByteValue()) {
                        //LOGGER.info("Closing connection due to connection not being accepted...");
                        connection.closeConnection(0);
                    }
                });
        }
    }