CorsHandler Class — netty Architecture

Source Code

codec-http/src/main/java/io/netty/handler/codec/http/cors/CorsHandler.java lines 53–288

public class CorsHandler extends ChannelDuplexHandler {

    private static final InternalLogger logger = InternalLoggerFactory.getInstance(CorsHandler.class);
    private static final String ANY_ORIGIN = "*";
    private static final String NULL_ORIGIN = "null";
    private CorsConfig config;

    private HttpRequest request;
    private final List<CorsConfig> configList;
    private final boolean isShortCircuit;
    private boolean consumeContent;

    /**
     * Creates a new instance with a single {@link CorsConfig}.
     */
    public CorsHandler(final CorsConfig config) {
        this(Collections.singletonList(checkNotNull(config, "config")), config.isShortCircuit());
    }

    /**
     * Creates a new instance with the specified config list. If more than one
     * config matches a certain origin, the first in the List will be used.
     *
     * @param configList     List of {@link CorsConfig}
     * @param isShortCircuit Same as {@link CorsConfig#isShortCircuit} but applicable to all supplied configs.
     */
    public CorsHandler(final List<CorsConfig> configList, boolean isShortCircuit) {
        checkNonEmpty(configList, "configList");
        this.configList = configList;
        this.isShortCircuit = isShortCircuit;
    }

    @Override
    public void channelRead(final ChannelHandlerContext ctx, final Object msg) throws Exception {
        if (msg instanceof HttpRequest) {
            request = (HttpRequest) msg;
            final String origin = request.headers().get(HttpHeaderNames.ORIGIN);
            config = getForOrigin(origin);
            if (isPreflightRequest(request)) {
                handlePreflight(ctx, request);
                // Enable consumeContent so that all following HttpContent
                // for this request will be released and not propagated downstream.
                consumeContent = true;
                return;
            }
            if (isShortCircuit && !(origin == null || config != null)) {
                forbidden(ctx, request);
                consumeContent = true;
                return;
            }

            // This request is forwarded, stop discarding
            consumeContent = false;
            ctx.fireChannelRead(msg);
            return;
        }

        if (consumeContent && (msg instanceof HttpContent)) {
            ReferenceCountUtil.release(msg);
            return;
        }

        ctx.fireChannelRead(msg);
    }

    private void handlePreflight(final ChannelHandlerContext ctx, final HttpRequest request) {
        final HttpResponse response = new DefaultFullHttpResponse(
                request.protocolVersion(),
                OK,
                Unpooled.buffer(0),
                DefaultHttpHeadersFactory.headersFactory().withCombiningHeaders(true),
                DefaultHttpHeadersFactory.trailersFactory().withCombiningHeaders(true));
        if (setOrigin(response)) {
            setAllowMethods(response);
            setAllowHeaders(response);
            setAllowCredentials(response);
            setMaxAge(response);
            setPreflightHeaders(response);
            setAllowPrivateNetwork(response);
        }
        if (!response.headers().contains(HttpHeaderNames.CONTENT_LENGTH)) {