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本文主要研究spring cloud gateway的XForwardedHeadersFilter

GatewayAutoConfiguration

spring-cloud-gateway-core-2.0.0.RC1-sources.jar!/org/springframework/cloud/gateway/config/GatewayAutoConfiguration.java

@Configuration
@ConditionalOnProperty(name = "spring.cloud.gateway.enabled", matchIfMissing = true)
@EnableConfigurationProperties
@AutoConfigureBefore(HttpHandlerAutoConfiguration.class)
@AutoConfigureAfter({GatewayLoadBalancerClientAutoConfiguration.class, GatewayClassPathWarningAutoConfiguration.class})
@ConditionalOnClass(DispatcherHandler.class)
public class GatewayAutoConfiguration {//......@Bean@ConditionalOnProperty(name = "spring.cloud.gateway.x-forwarded.enabled", matchIfMissing = true)public XForwardedHeadersFilter xForwardedHeadersFilter() {return new XForwardedHeadersFilter();}//......
}

默认注册了XForwardedHeadersFilter

XForwardedHeadersFilter

spring-cloud-gateway-core-2.0.0.RC1-sources.jar!/org/springframework/cloud/gateway/filter/headers/XForwardedHeadersFilter.java

@ConfigurationProperties("spring.cloud.gateway.x-forwarded")
public class XForwardedHeadersFilter implements HttpHeadersFilter, Ordered {//......@Overridepublic HttpHeaders filter(HttpHeaders input, ServerWebExchange exchange) {ServerHttpRequest request = exchange.getRequest();HttpHeaders original = input;HttpHeaders updated = new HttpHeaders();original.entrySet().stream().forEach(entry -> updated.addAll(entry.getKey(), entry.getValue()));if (isForEnabled()) {String remoteAddr = request.getRemoteAddress().getAddress().getHostAddress();List<String> xforwarded = original.get(X_FORWARDED_FOR_HEADER);// prevent duplicatesif (remoteAddr != null &&(xforwarded == null || !xforwarded.contains(remoteAddr))) {write(updated, X_FORWARDED_FOR_HEADER, remoteAddr, isForAppend());}}String proto = request.getURI().getScheme();if (isProtoEnabled()) {write(updated, X_FORWARDED_PROTO_HEADER, proto, isProtoAppend());}if (isPortEnabled()) {String port = String.valueOf(request.getURI().getPort());if (request.getURI().getPort() < 0) {port = String.valueOf(getDefaultPort(proto));}write(updated, X_FORWARDED_PORT_HEADER, port, isPortAppend());}if (isHostEnabled()) {String host = toHostHeader(request);write(updated, X_FORWARDED_HOST_HEADER, host, isHostAppend());}return updated;}//......
}

• 如果spring.cloud.gateway.x-forwarded.for-enabled为true，则会写入X-Forwarded-For
• 如果spring.cloud.gateway.x-forwarded.proto-enabled为true，则会写入X-Forwarded-Proto
• 如果spring.cloud.gateway.x-forwarded.port-enabled为true，则会写入X-Forwarded-Port
• 如果spring.cloud.gateway.x-forwarded.host-enabled为true，则会写入X-Forwarded-Host

每个enable属性都有一个append属性，用来决定是否是添加还是追加

    private void write(HttpHeaders headers, String name, String value, boolean append) {if (append) {headers.add(name, value);// these headers should be treated as a single comma separated headerList<String> values = headers.get(name);String delimitedValue = StringUtils.collectionToCommaDelimitedString(values);headers.set(name, delimitedValue);} else {headers.set(name, value);}}

如果是append，则逗号分隔写入headers，如果不是则是采取set操作。

配置

    {"sourceType": "org.springframework.cloud.gateway.filter.headers.XForwardedHeadersFilter","defaultValue": true,"name": "spring.cloud.gateway.x-forwarded.enabled","description": "If the XForwardedHeadersFilter is enabled.","type": "java.lang.Boolean"},{"sourceType": "org.springframework.cloud.gateway.filter.headers.XForwardedHeadersFilter","defaultValue": true,"name": "spring.cloud.gateway.x-forwarded.for-append","description": "If appending X-Forwarded-For as a list is enabled.","type": "java.lang.Boolean"},{"sourceType": "org.springframework.cloud.gateway.filter.headers.XForwardedHeadersFilter","defaultValue": true,"name": "spring.cloud.gateway.x-forwarded.for-enabled","description": "If X-Forwarded-For is enabled.","type": "java.lang.Boolean"},{"sourceType": "org.springframework.cloud.gateway.filter.headers.XForwardedHeadersFilter","defaultValue": true,"name": "spring.cloud.gateway.x-forwarded.host-append","description": "If appending X-Forwarded-Host as a list is enabled.","type": "java.lang.Boolean"},{"sourceType": "org.springframework.cloud.gateway.filter.headers.XForwardedHeadersFilter","defaultValue": true,"name": "spring.cloud.gateway.x-forwarded.host-enabled","description": "If X-Forwarded-Host is enabled.","type": "java.lang.Boolean"},{"sourceType": "org.springframework.cloud.gateway.filter.headers.XForwardedHeadersFilter","defaultValue": 0,"name": "spring.cloud.gateway.x-forwarded.order","description": "The order of the XForwardedHeadersFilter.","type": "java.lang.Integer"},{"sourceType": "org.springframework.cloud.gateway.filter.headers.XForwardedHeadersFilter","defaultValue": true,"name": "spring.cloud.gateway.x-forwarded.port-append","description": "If appending X-Forwarded-Port as a list is enabled.","type": "java.lang.Boolean"},{"sourceType": "org.springframework.cloud.gateway.filter.headers.XForwardedHeadersFilter","defaultValue": true,"name": "spring.cloud.gateway.x-forwarded.port-enabled","description": "If X-Forwarded-Port is enabled.","type": "java.lang.Boolean"},{"sourceType": "org.springframework.cloud.gateway.filter.headers.XForwardedHeadersFilter","defaultValue": true,"name": "spring.cloud.gateway.x-forwarded.proto-append","description": "If appending X-Forwarded-Proto as a list is enabled.","type": "java.lang.Boolean"},{"sourceType": "org.springframework.cloud.gateway.filter.headers.XForwardedHeadersFilter","defaultValue": true,"name": "spring.cloud.gateway.x-forwarded.proto-enabled","description": "If X-Forwarded-Proto is enabled.","type": "java.lang.Boolean"}

小结

spring cloud gateway提供了XForwardedHeadersFilter，用来决定进行路由转发的时候转发哪些X-Forwarded相关的header，同时提供append选项，用来控制是否是追加还是覆盖到header中。

doc

• _modifying_the_way_remote_addresses_are_resolved