SpringCloud gateway request的body验证或修改方式

SpringCloud gateway request的body验证或修改

后续版本新增了以下过滤器

org.springframework.cloud.gateway.filter.headers.RemoveHopByHopHeadersFilter

默认会把以下头部移除（暂不了解这做法的目的）

- connection

- keep-alive

- te

- transfer-encoding

- trailer

- proxy-authorization

- proxy-authenticate

- x-application-context

- upgrade

从而导致下面我们重写getHeaders方法时添加的transfer-encoding头部移除，导致无法解析body。

解决办法：

在yml文件中配置自定义的头部移除列表

spring:
  cloud:
      filter:
        remove-hop-by-hop:
          headers:
            - connection
            - keep-alive
            - te
            - trailer
            - proxy-authorization
            - proxy-authenticate
            - x-application-context
            - upgrade

源码可见链接，且可实现动态路由配置：https://github.com/SingleTigger/SpringCloudGateway-Nacos-Demo

------------原文------------

往往业务中我们需要在网关对请求参数作修改操作（注意以下只针对带有body的请求），springcloud gateway中有提供一个

ModifyRequestBodyGatewayFilterFactory的filter，看了一下它的实现，需要指定输入类型和输出类型，比较局限。

我就参考它自己实现了一个拦截器

注意：上传文件也带有请求body，需特殊处理。

以下是主要代码

import org.springframework.cloud.gateway.filter.GatewayFilter;
import org.springframework.cloud.gateway.filter.factory.AbstractGatewayFilterFactory;
import org.springframework.cloud.gateway.support.BodyInserterContext;
import org.springframework.core.io.buffer.DataBuffer;
import org.springframework.http.HttpHeaders;
import org.springframework.http.codec.HttpMessageReader;
import org.springframework.http.server.reactive.ServerHttpRequest;
import org.springframework.http.server.reactive.ServerHttpRequestDecorator;
import org.springframework.stereotype.Component;
import org.springframework.web.reactive.function.BodyInserter;
import org.springframework.web.reactive.function.BodyInserters;
import org.springframework.web.reactive.function.server.HandlerStrategies;
import org.springframework.web.reactive.function.server.ServerRequest;
import org.springframework.web.server.ServerWebExchange;
import reactor.core.publisher.Flux;
import reactor.core.publisher.Mono;

import java.util.List;
import java.util.concurrent.atomic.AtomicReference;
import java.util.function.BiFunction;

/**
 * @author chenws
 * @date 2019/12/12 09:33:53
 */
@Component
public class CModifyRequestBodyGatewayFilterFactory extends AbstractGatewayFilterFactory {
    private final List<HttpMessageReader<?>> messageReaders;
    public CModifyRequestBodyGatewayFilterFactory() {
        this.messageReaders = HandlerStrategies.withDefaults().messageReaders();
    }

    @Override
    @SuppressWarnings("unchecked")
    public GatewayFilter apply(Object config) {
        return (exchange, chain) -> {
            ServerRequest serverRequest = ServerRequest.create(exchange,
                    this.messageReaders);

            Mono<String> modifiedBody = serverRequest.bodyToMono(String.class)
                    .flatMap(originalBody -> modifyBody()
                            .apply(exchange,Mono.just(originalBody)));

            BodyInserter bodyInserter = BodyInserters.fromPublisher(modifiedBody,
                    String.class);
            HttpHeaders headers = new HttpHeaders();
            headers.putAll(exchange.getRequest().getHeaders());
            headers.remove(HttpHeaders.CONTENT_LENGTH);

            CachedBodyOutputMessage outputMessage = new CachedBodyOutputMessage(exchange,
                    headers);
            return bodyInserter.insert(outputMessage, new BodyInserterContext())
                    .then(Mono.defer(() -> {
                        ServerHttpRequest decorator = decorate(exchange, headers,
                                outputMessage);
                        return chain.filter(exchange.mutate().request(decorator).build());
                    }));
        };
    }

    /**
     * 修改body
     * @return apply 返回Mono<String>，数据是修改后的body
     */
    private BiFunction<ServerWebExchange,Mono<String>,Mono<String>> modifyBody(){
        return (exchange,json)-> {
            AtomicReference<String> result = new AtomicReference<>();
            json.subscribe(
                    value -> {
                        //value 即为请求body，在此处修改
                        result.set(value);
                        System.out.println(result.get());
                    },
                    Throwable::printStackTrace
            );
            return Mono.just(result.get());
        };
    }

    private ServerHttpRequestDecorator decorate(ServerWebExchange exchange, HttpHeaders headers,
                                        CachedBodyOutputMessage outputMessage) {
        return new ServerHttpRequestDecorator(exchange.getRequest()) {
            @Override
            public HttpHeaders getHeaders() {
                long contentLength = headers.getContentLength();
                HttpHeaders httpHeaders = new HttpHeaders();
                httpHeaders.putAll(super.getHeaders());
                if (contentLength > 0) {
                    httpHeaders.setContentLength(contentLength);
                }
                else {
                    httpHeaders.set(HttpHeaders.TRANSFER_ENCODING, "chunked");
                }
                return httpHeaders;
            }

            @Override
            public Flux<DataBuffer> getBody() {
                return outputMessage.getBody();
            }
        };
    }
}

SpringCloud Gateway获取post请求体(request body)不完整解决方案

Spring Cloud Gateway做为网关服务，通过gateway进行请求转发，在请求到达后端服务前我们可以通过filter进行一些预处理如：请求的合法性，商户验证等。

如我们在请求体中添加商户ID（merId）和商户KEY（merkey），通过此来验证请求的合法性。但是如果我们请求内容太长如转为base64的文件存储请求。此时我们在filter获取body内容就会被截取(太长的 Body 会被截断)。目前网上也没有好的解决方式。

springboot及Cloud版本如下；

这里提供一种解决方式，相关代码如下：

1.Requestfilter

我们采用Gateway网关的Gobalfilter，建立我们的第一个过滤器过滤所有请求。

1).通过Spring 5 的 WebFlux我们使用bodyToMono方法把响应内容转换成类 String的对象，最终得到的结果是 Mono对象

2).bodyToMono方法我们可以拿到完整的body内容，并返回String。

3).我们生成唯一的token（通过UUID），并将token放入请求的header中。

4).将获取到的完整body内容，存放到redis中。

@Component
public class RequestFilter implements GlobalFilter, Ordered {
	@Autowired
	private RedisClientTemplate redisClientTemplate;
	@Override
	public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
		DefaultServerRequest req = new DefaultServerRequest( exchange );
		String token = UUID.randomUUID().toString();
		//向headers中放入token信息
		ServerHttpRequest serverHttpRequest =exchange.getRequest().mutate().header("token", token)
				.build();
		//将现在的request变成change对象
		ServerWebExchange build = exchange.mutate().request( serverHttpRequest ).build();
		return req.bodyToMono( String.class ).map( str -> {
			redisClientTemplate.setObjex( "microservice:gateway:".concat( token ), 180, str );
			MySlf4j.textInfo( "请求参数:{0}", str );
			return str;
		} ).then( chain.filter( build ) );
	}
	@Override
	public int getOrder() {
		return 0;
	}
}

2.MerchantAuthFilter

建立商户认证过滤器，相关代码如下：

1).获取存储在headers中的token。

2).通过token获取我们存储在redis中的body内容(WebFlux 中不能使用阻塞的操作，目前想到的是通过这种方式实现)。

3).获取到完整的body内容后我们就可以进行相应的商户认证操作。

4).认证通过，将信息重新写入，不通过则返回异常信息。

@Override
public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
	/** 验证商户是否有权限访问 */
	ServerHttpRequest serverHttpRequest = exchange.getRequest();
	String token = serverHttpRequest.getHeaders().get( "token" ).get( 0 );
       String bodyStr = (String) redisClientTemplate.getObj("microservice:gateway:".concat(token));
	BaseReqVo baseReqVo = JsonUtil.fromJson( bodyStr, BaseReqVo.class );
	try {
		// 商户认证
		BaseRespVo<?> baseRespVo = merchantAuthService.checkMerchantAuth( baseReqVo );
		if (MicroserviceConstantParamUtils.RESULT_CODE_SUCC.equals( baseRespVo.getCode() )) {
               // 若验证成功，将信息重新写入避免request信息消费后后续无法从request获取信息的问题
               URI uri = serverHttpRequest.getURI();
               ServerHttpRequest request = serverHttpRequest.mutate().uri(uri).build();
               DataBuffer bodyDataBuffer = stringBuffer(bodyStr);
               Flux<DataBuffer> bodyFlux = Flux.just(bodyDataBuffer);
               request = new ServerHttpRequestDecorator(request) {
                   @Override
                   public Flux<DataBuffer> getBody() {
                       return bodyFlux;
                   }
               };
			// 封装request，传给下一级
               return chain.filter(exchange.mutate().request(request).build());
		} else {
			// 若验证不成功，返回提示信息
			return gatewayResponse( baseRespVo.getCode(), baseRespVo.getMessage(), exchange );
		}
	} catch (MicroserviceServiceException ex) {
		// 若验证不成功，返回提示信息
		MySlf4j.textError( "商户访问权限验证异常，异常代码:{0},异常信息:{1}, 异常{2}", ex.getCode(), ex.getMessage(), ex );
		return gatewayResponse( ex.getCode(), ex.getMessage(), exchange );
	} catch (Exception ex) {
		MySlf4j.textError( "商户访问权限验证服务异常:{0}", LogUtil.ExceptionToString( ex ) );
		return gatewayResponse( MicroserviceException.ERR_100000, "系统异常", exchange );
	} finally {
		redisClientTemplate.del( "microservice:gateway:".concat( token ) );
	}
}
/**数据流处理方法*/
private DataBuffer stringBuffer(String value) {
	byte[] bytes = value.getBytes( StandardCharsets.UTF_8 );
	NettyDataBufferFactory nettyDataBufferFactory = new NettyDataBufferFactory( ByteBufAllocator.DEFAULT );
	DataBuffer buffer = nettyDataBufferFactory.allocateBuffer( bytes.length );
	buffer.write( bytes );
	return buffer;
}
/**网关请求响应*/
private Mono<Void> gatewayResponse(String code, String message, ServerWebExchange exchange) {
	// 若验证不成功，返回提示信息
	ServerHttpResponse response = exchange.getResponse();
	BaseRespVo<T> baseRespVo = ResponseUtils.responseMsg( code, message, null );
	byte[] bits = JsonUtil.toJson( baseRespVo ).getBytes( StandardCharsets.UTF_8 );
	DataBuffer buffer = response.bufferFactory().wrap( bits );
	response.setStatusCode( HttpStatus.UNAUTHORIZED );
	// 指定编码，否则在浏览器中会中文乱码
	response.getHeaders().add( "Content-Type", "text/plain;charset=UTF-8" );
	return response.writeWith( Mono.just( buffer ) );
}
@Override
public int getOrder() {
	return 1;
}

另外我们还可以通过GlobalFilter实现请求过滤，OAUTH授权，相关代码如下：

请求方式验证过滤器（RequestAuthFilter）：

@Override
public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
 ServerHttpRequest serverHttpRequest = exchange.getRequest();
 String method = serverHttpRequest.getMethodValue();
 if (!"POST".equals(method)) {
  ServerHttpResponse response = exchange.getResponse();
  BaseRespVo<T> baseRespVo = ResponseUtils.responseMsg(MicroserviceException.ERR_100008, "非法请求", null);
  byte[] bits = JsonUtil.toJson(baseRespVo).getBytes(StandardCharsets.UTF_8);
  DataBuffer buffer = response.bufferFactory().wrap(bits);
  response.setStatusCode(HttpStatus.UNAUTHORIZED);
  //指定编码，否则在浏览器中会中文乱码
  response.getHeaders().add("Content-Type", "text/plain;charset=UTF-8");
  return response.writeWith(Mono.just(buffer));
 }
 return chain.filter(exchange);
 }

OAUTH授权过滤器（OAuthSignatureFilter）：

/**授权访问用户名*/
@Value("${spring.security.user.name}")
private String securityUserName;
/**授权访问密码*/
@Value("${spring.security.user.password}")
private String securityUserPassword;
@Override
public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
 /**oauth授权*/
 String auth = securityUserName.concat(":").concat(securityUserPassword);
 String encodedAuth = new sun.misc.BASE64Encoder().encode(auth.getBytes(Charset.forName("US-ASCII")));
 String authHeader = "Basic " + encodedAuth;
 //向headers中放授权信息
 ServerHttpRequest serverHttpRequest = exchange.getRequest().mutate().header("Authorization", authHeader)
   .build();
 //将现在的request变成change对象
 ServerWebExchange build = exchange.mutate().request(serverHttpRequest).build();
 return chain.filter(build);
}

以上为个人经验，希望能给大家一个参考，也希望大家多多支持我们。