笔记 20240604

2024-10-25
辽宁
本文字数：2775 字
阅读完需：约 9 分钟

记一次 Spring Cloud Gateway 的 Filter 重复执行两次的问题

背景：公司开放平台使用 Spring Cloud Gateway 搭建了的开放网关，统一所有开放资源接口路由。今天突然有客户反馈接口请求报错，错误信息是 nonce 参数重复导致的验签不通过，但客户确认使用的 uuid 最为 nonce 参数所以几乎不可能重复。
排查过程：
根据异常定位代码位置，得出是 nonce 参数重复导致的验签不通过。nonce 的作用类似于 requestId 避免重复的请求，代码中 nonce 使用 redis 缓存一小时
使用客户提供的参数在生产稳定复现问题
在测试环境 debug 发现验签的 GatewayFilter（MroGatewayFilter）重复执行了两次，导致一次请求的 nonce 重复校验两次自然不通过
经过半天的排查和 debug 最终发现问题，是由于代码中有个修改 Response 的 GlobalFilter（GatewayModifyResponseGatewayFilter）存在 Bug，在重写 ResponseBody 时又去调用了 chain.filter(exchange)。这样就会导致重复执行 Filter
代码如下

GatewayFilter（MroGatewayFilter）

package cn.yzw.uop.gateway.filter.extend;
import lombok.extern.slf4j.Slf4j;import org.springframework.cloud.gateway.filter.GatewayFilter;import org.springframework.cloud.gateway.filter.GatewayFilterChain;import org.springframework.core.Ordered;import org.springframework.stereotype.Component;import org.springframework.web.server.ServerWebExchange;import reactor.core.publisher.Mono;

/** * @author luojianbo * @date 2023/11/8 */@Slf4j@Componentpublic class MroGatewayFilter implements GatewayFilter, Ordered {        @Override    public int getOrder() {        return 0;    }
    @Override    public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {        // 重复执行两次！！！        // todo something......        return chain.filter(exchange);    }}

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GlobalFilter（GatewayModifyResponseGatewayFilter）存在 Bug

public class GatewayModifyResponseGatewayFilter implements GlobalFilter, Ordered {
    @Override    @SuppressWarnings("unchecked")    public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {        WatchUtils.point(exchange, "GatewayModifyResponseGatewayFilter start");        ServerHttpResponseDecorator responseDecorator = new ServerHttpResponseDecorator(exchange.getResponse()) {
            @Override            public Mono<Void> writeWith(Publisher<? extends DataBuffer> body) {                if (exchange.getAttribute(SopConstants.RESTFUL_REQUEST) != null) {                    WatchUtils.point(exchange, "GatewayModifyResponseGatewayFilter end");                    return chain.filter(exchange); // 问题就出在这里，这里只是一个Response装饰器不能去调用下一个过滤器，正确的做法实在filter方法去调用下一个过滤器chain.filter(exchange)                }                byte[] bits = JSONObject.toJSONString("新的body内容").getBytes(StandardCharsets.UTF_8);                DataBuffer buffer = exchange.getResponse().bufferFactory().wrap(bits);                exchange.getResponse().setStatusCode(HttpStatus.OK);                exchange.getResponse().getHeaders().setContentType(MediaType.APPLICATION_JSON);                return exchange.getResponse().writeWith(Mono.just(buffer));            }
            @Override            public Mono<Void> writeAndFlushWith(Publisher<? extends Publisher<? extends DataBuffer>> body) {                return writeWith(Flux.from(body)                        .flatMapSequential(p -> p));            }        };        return chain.filter(exchange.mutate().response(responseDecorator).build());    }      @Override    public int getOrder() {        return NettyWriteResponseFilter.WRITE_RESPONSE_FILTER_ORDER - 1;    }}

复制代码

修复后的 GatewayModifyResponseGatewayFilter

public class GatewayModifyResponseGatewayFilter implements GlobalFilter, Ordered {
    @Override    @SuppressWarnings("unchecked")    public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {        WatchUtils.point(exchange, "GatewayModifyResponseGatewayFilter start");        ServerHttpResponseDecorator responseDecorator = new ServerHttpResponseDecorator(exchange.getResponse()) {
            @Override            public Mono<Void> writeWith(Publisher<? extends DataBuffer> body) {                byte[] bits = JSONObject.toJSONString("新的body内容").getBytes(StandardCharsets.UTF_8);                DataBuffer buffer = exchange.getResponse().bufferFactory().wrap(bits);                exchange.getResponse().setStatusCode(HttpStatus.OK);                exchange.getResponse().getHeaders().setContentType(MediaType.APPLICATION_JSON);                return exchange.getResponse().writeWith(Mono.just(buffer));            }
            @Override            public Mono<Void> writeAndFlushWith(Publisher<? extends Publisher<? extends DataBuffer>> body) {                return writeWith(Flux.from(body)                        .flatMapSequential(p -> p));            }        };      if (exchange.getAttribute(SopConstants.RESTFUL_REQUEST) != null) {                    WatchUtils.point(exchange, "GatewayModifyResponseGatewayFilter end");                    return chain.filter(exchange); // 在这里去调用下一个过滤器才是正确的                }        return chain.filter(exchange.mutate().response(responseDecorator).build());    }      @Override    public int getOrder() {        return NettyWriteResponseFilter.WRITE_RESPONSE_FILTER_ORDER - 1;    }}