Netty报错：Max frame length of 65536 has been exceeded 的解决

谁践踏了优雅 2023-07-10 11:21 15阅读 0赞

转载自：[https://blog.csdn.net/maoyuanming0806/article/details/80199647][https_blog.csdn.net_maoyuanming0806_article_details_80199647]

## 异常信息 ##

io.netty.handler.codec.CorruptedFrameException: Max frame length of 65536 has been exceeded.
        at io.netty.handler.codec.http.websocketx.WebSocket08FrameDecoder.protocolViolation(WebSocket08FrameDecoder.java:412)
        at io.netty.handler.codec.http.websocketx.WebSocket08FrameDecoder.decode(WebSocket08FrameDecoder.java:277)
        at io.netty.handler.codec.ByteToMessageDecoder.decodeRemovalReentryProtection(ByteToMessageDecoder.java:489)
        at io.netty.handler.codec.ByteToMessageDecoder.callDecode(ByteToMessageDecoder.java:428)
        at io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:265)
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362)
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348)
        at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:340)
        at io.netty.channel.DefaultChannelPipeline$HeadContext.channelRead(DefaultChannelPipeline.java:1334)
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362)
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348)
        at io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:926)
        at io.netty.channel.nio.AbstractNioByteChannel$NioByteUnsafe.read(AbstractNioByteChannel.java:134)
        at io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:644)
        at io.netty.channel.nio.NioEventLoop.processSelectedKeysOptimized(NioEventLoop.java:579)
        at io.netty.channel.nio.NioEventLoop.processSelectedKeys(NioEventLoop.java:496)
        at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:458)
        at io.netty.util.concurrent.SingleThreadEventExecutor$5.run(SingleThreadEventExecutor.java:858)
        at io.netty.util.concurrent.DefaultThreadFactory$DefaultRunnableDecorator.run(DefaultThreadFactory.java:138)
        at java.lang.Thread.run(Thread.java:745)

## 原因 ##

字符串太大了，netty解析失败。

## 解决 ##

（1）可以数据发送端数据包分包发送（分段发送），如果逻辑上可行

（2）或者调大接收数据包大小，在建立socket握手的时候。

![20200302101648640.png][]

WebSocketServerHandshakerFactory类源码如下

/**
     * Creates a new {@link WebSocketClientHandshaker} of desired protocol version.
     */
    public final class WebSocketClientHandshakerFactory {
    
        /**
         * Private constructor so this static class cannot be instanced.
         */
        private WebSocketClientHandshakerFactory() {
        }
    
        /**
         * Creates a new handshaker.
         *
         * @param webSocketURL
         *            URL for web socket communications. e.g "ws://myhost.com/mypath".
         *            Subsequent web socket frames will be sent to this URL.
         * @param version
         *            Version of web socket specification to use to connect to the server
         * @param subprotocol
         *            Sub protocol request sent to the server. Null if no sub-protocol support is required.
         * @param allowExtensions
         *            Allow extensions to be used in the reserved bits of the web socket frame
         * @param customHeaders
         *            Custom HTTP headers to send during the handshake
         */
        public static WebSocketClientHandshaker newHandshaker(
                URI webSocketURL, WebSocketVersion version, String subprotocol,
                boolean allowExtensions, HttpHeaders customHeaders) {
            return newHandshaker(webSocketURL, version, subprotocol, allowExtensions, customHeaders, 65536);
        }
    
        /**
         * Creates a new handshaker.
         *
         * @param webSocketURL
         *            URL for web socket communications. e.g "ws://myhost.com/mypath".
         *            Subsequent web socket frames will be sent to this URL.
         * @param version
         *            Version of web socket specification to use to connect to the server
         * @param subprotocol
         *            Sub protocol request sent to the server. Null if no sub-protocol support is required.
         * @param allowExtensions
         *            Allow extensions to be used in the reserved bits of the web socket frame
         * @param customHeaders
         *            Custom HTTP headers to send during the handshake
         * @param maxFramePayloadLength
         *            Maximum allowable frame payload length. Setting this value to your application's
         *            requirement may reduce denial of service attacks using long data frames.
         */
        public static WebSocketClientHandshaker newHandshaker(
                URI webSocketURL, WebSocketVersion version, String subprotocol,
                boolean allowExtensions, HttpHeaders customHeaders, int maxFramePayloadLength) {
            return newHandshaker(webSocketURL, version, subprotocol, allowExtensions, customHeaders,
                                 maxFramePayloadLength, true, false);
        }
    
        /**
         * Creates a new handshaker.
         *
         * @param webSocketURL
         *            URL for web socket communications. e.g "ws://myhost.com/mypath".
         *            Subsequent web socket frames will be sent to this URL.
         * @param version
         *            Version of web socket specification to use to connect to the server
         * @param subprotocol
         *            Sub protocol request sent to the server. Null if no sub-protocol support is required.
         * @param allowExtensions
         *            Allow extensions to be used in the reserved bits of the web socket frame
         * @param customHeaders
         *            Custom HTTP headers to send during the handshake
         * @param maxFramePayloadLength
         *            Maximum allowable frame payload length. Setting this value to your application's
         *            requirement may reduce denial of service attacks using long data frames.
         * @param performMasking
         *            Whether to mask all written websocket frames. This must be set to true in order to be fully compatible
         *            with the websocket specifications. Client applications that communicate with a non-standard server
         *            which doesn't require masking might set this to false to achieve a higher performance.
         * @param allowMaskMismatch
         *            When set to true, frames which are not masked properly according to the standard will still be
         *            accepted.
         */
        public static WebSocketClientHandshaker newHandshaker(
                URI webSocketURL, WebSocketVersion version, String subprotocol,
                boolean allowExtensions, HttpHeaders customHeaders, int maxFramePayloadLength,
                boolean performMasking, boolean allowMaskMismatch) {
            if (version == V13) {
                return new WebSocketClientHandshaker13(
                        webSocketURL, V13, subprotocol, allowExtensions, customHeaders,
                        maxFramePayloadLength, performMasking, allowMaskMismatch);
            }
            if (version == V08) {
                return new WebSocketClientHandshaker08(
                        webSocketURL, V08, subprotocol, allowExtensions, customHeaders,
                        maxFramePayloadLength, performMasking, allowMaskMismatch);
            }
            if (version == V07) {
                return new WebSocketClientHandshaker07(
                        webSocketURL, V07, subprotocol, allowExtensions, customHeaders,
                        maxFramePayloadLength, performMasking, allowMaskMismatch);
            }
            if (version == V00) {
                return new WebSocketClientHandshaker00(
                        webSocketURL, V00, subprotocol, customHeaders, maxFramePayloadLength);
            }
    
            throw new WebSocketHandshakeException("Protocol version " + version + " not supported.");
        }
    }

只有三个构造方法，其中的构造参数中：**`maxFramePayloadLength`**是设置为最大数据帧的长度。

若不设置，那么如源码中有默认值为：65536。源码中也有说明：

Maximum allowable frame payload length. Setting this value to your application's requirement may reduce denial of service attacks using long data frames.

意思就是：数据帧最大长度，合理设置可避免大数据包攻击你的服务器

个人解决：扩大数据帧长度即可

WebSocketServerHandshakerFactory wsFactory = 
    new WebSocketServerHandshakerFactory(uri,WebSocketVersion.V13, null,true,new DefaultHttpHeaders(), 65536*5);

[https_blog.csdn.net_maoyuanming0806_article_details_80199647]: https://blog.csdn.net/maoyuanming0806/article/details/80199647
[20200302101648640.png]: https://img-blog.csdnimg.cn/20200302101648640.png