WebSocketUtil Class — netty Architecture

Source Code

codec-http/src/main/java/io/netty/handler/codec/http/websocketx/WebSocketUtil.java lines 28–153

final class WebSocketUtil {

    private static final FastThreadLocal<MessageDigest> MD5 = new FastThreadLocal<MessageDigest>() {
        @Override
        protected MessageDigest initialValue() throws Exception {
            try {
                //Try to get a MessageDigest that uses MD5
                //Suppress a warning about weak hash algorithm
                //since it's defined in draft-ietf-hybi-thewebsocketprotocol-00
                return MessageDigest.getInstance("MD5");
            } catch (NoSuchAlgorithmException e) {
                //This shouldn't happen! How old is the computer?
                throw new InternalError("MD5 not supported on this platform - Outdated?");
            }
        }
    };

    private static final FastThreadLocal<MessageDigest> SHA1 = new FastThreadLocal<MessageDigest>() {
        @Override
        protected MessageDigest initialValue() throws Exception {
            try {
                //Try to get a MessageDigest that uses SHA1
                //Suppress a warning about weak hash algorithm
                //since it's defined in draft-ietf-hybi-thewebsocketprotocol-00
                return MessageDigest.getInstance("SHA1");
            } catch (NoSuchAlgorithmException e) {
                //This shouldn't happen! How old is the computer?
                throw new InternalError("SHA-1 not supported on this platform - Outdated?");
            }
        }
    };

    /**
     * Performs a MD5 hash on the specified data
     *
     * @param data The data to hash
     * @return The hashed data
     */
    static byte[] md5(byte[] data) {
        // TODO(normanmaurer): Create md5 method that not need MessageDigest.
        return digest(MD5, data);
    }

    /**
     * Performs a SHA-1 hash on the specified data
     *
     * @param data The data to hash
     * @return The hashed data
     */
    static byte[] sha1(byte[] data) {
        // TODO(normanmaurer): Create sha1 method that not need MessageDigest.
        return digest(SHA1, data);
    }

    private static byte[] digest(FastThreadLocal<MessageDigest> digestFastThreadLocal, byte[] data) {
        MessageDigest digest = digestFastThreadLocal.get();
        digest.reset();
        return digest.digest(data);
    }

    /**
     * Performs base64 encoding on the specified data
     *
     * @param data The data to encode
     * @return An encoded string containing the data
     */
    static String base64(byte[] data) {
        return Base64.getEncoder().encodeToString(data);
    }

    /**
     * Creates an arbitrary number of random bytes
     *
     * @param size the number of random bytes to create
     * @return An array of random bytes
     */
    static byte[] randomBytes(int size) {
        byte[] bytes = new byte[size];
        ThreadLocalRandom.current().nextBytes(bytes);
        return bytes;
    }