package com.jinw.cms.aspectj;

import com.jinw.cms.aspectj.annotation.XssIgnore;
import org.springframework.web.method.HandlerMethod;
import org.springframework.web.servlet.AsyncHandlerInterceptor;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.util.Objects;

public class XssInterceptor implements AsyncHandlerInterceptor {

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)
            throws Exception {
        if (handler instanceof HandlerMethod) {
            HandlerMethod handlerMethod = (HandlerMethod) handler;
            XssIgnore xssIgnore = handlerMethod.getMethodAnnotation(XssIgnore.class);
            if (Objects.nonNull(xssIgnore)) {
                XssContextHolder.ignore();
            }
        }
        return true;
    }

    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex)
            throws Exception {
        XssContextHolder.remove();
    }

    /**
     * 如果返回一个current类型的变量，会启用一个新的线程。执行完preHandle方法之后立即会调用afterConcurrentHandlingStarted
     * 然后新线程再以次执行preHandle,postHandle,afterCompletion**
     */
    @Override
    public void afterConcurrentHandlingStarted(HttpServletRequest request, HttpServletResponse response, Object handler)
            throws Exception {
        XssContextHolder.remove();
    }
}

package com.jinw.cms.aspectj;

import com.fasterxml.jackson.core.JacksonException;
import com.fasterxml.jackson.core.JsonParser;
import com.fasterxml.jackson.core.JsonToken;
import com.fasterxml.jackson.databind.DeserializationContext;
import com.fasterxml.jackson.databind.JsonDeserializer;
import com.fasterxml.jackson.databind.JsonMappingException;
import com.fasterxml.jackson.databind.type.LogicalType;
import com.jinw.cms.entity.XssMode;
import com.jinw.utils.cms.HtmlUtils;
import com.jinw.utils.cms.StringUtils;
import lombok.RequiredArgsConstructor;

import java.io.IOException;
import java.util.Objects;

@RequiredArgsConstructor
public class XssDeserializer extends JsonDeserializer<String> {

    private final XssMode mode;

    @Override
    public LogicalType logicalType() {
        return LogicalType.Textual;
    }

    @Override
    public String getNullValue(DeserializationContext ctxt) throws JsonMappingException {
        return StringUtils.EMPTY;
    }

    @Override
    public String deserialize(JsonParser p, DeserializationContext ctxt) throws IOException, JacksonException {
        if (p.hasToken(JsonToken.VALUE_STRING)) {
            return deal(p.getText());
        }
        JsonToken token = p.getCurrentToken();
        if (token.isScalarValue()) {
            String text = p.getValueAsString();
            if (text != null) {
                return text;
            }
        }
        return (String) ctxt.handleUnexpectedToken(String.class, p);
    }

    private String deal(String text) {
        if (Objects.nonNull(text) && !XssContextHolder.isIgnore()) {
            if (mode == XssMode.CLEAN) {
                text = HtmlUtils.clean(text);
            } else {
                text = HtmlUtils.escape(text);
            }
        }
        return text;
    }
}

package com.jinw.cms.aspectj;

import java.util.Objects;

public class XssContextHolder {

    private static final ThreadLocal<Boolean> CONTEXT = new ThreadLocal<>();

    /**
     * 默认为true
     */
    public static boolean isIgnore() {
        return Objects.isNull(CONTEXT.get()) ? true : CONTEXT.get();
    }

    public static void ignore() {
        CONTEXT.set(true);
    }

    public static void remove() {
        CONTEXT.remove();
    }
}

package com.jinw.cms.config.properties;

import com.jinw.cms.entity.XssMode;
import lombok.Getter;
import lombok.Setter;
import org.springframework.boot.context.properties.ConfigurationProperties;

import java.util.List;

@Setter
@Getter
@ConfigurationProperties(prefix = "xss")
public class XssProperties {

    /**
     * 是否开启XSS过滤
     */
    private boolean enabled;

    /**
     * 处理方式
     */
    private XssMode mode;

    /**
     * 不进行处理的路径
     */
    private List<String> excludes;

    /**
     * 处理指定路径
     */
    private List<String> urlPatterns;
}

package com.jinw.cms.config;

import com.google.common.collect.Lists;
import com.jinw.cms.aspectj.XssDeserializer;
import com.jinw.cms.aspectj.XssInterceptor;
import com.jinw.cms.config.properties.XssProperties;
import com.jinw.utils.cms.StringUtils;
import lombok.RequiredArgsConstructor;
import org.springframework.boot.autoconfigure.jackson.Jackson2ObjectMapperBuilderCustomizer;
import org.springframework.boot.context.properties.EnableConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.Ordered;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

import java.util.Collections;
import java.util.List;

@RequiredArgsConstructor
@Configuration
@EnableConfigurationProperties(XssProperties.class)
public class XssConfig implements WebMvcConfigurer {

    private final XssProperties xssProperties;

    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        if (xssProperties.isEnabled()) {
            List<String> urlPatterns = xssProperties.getUrlPatterns();
            if (StringUtils.isEmpty(urlPatterns)) {
                urlPatterns = Lists.newArrayList();
                urlPatterns.add("/**");
            }
            List<String> excludes = xssProperties.getExcludes();
            if (StringUtils.isEmpty(excludes)) {
                excludes = Collections.emptyList();
            }
            //addPathPatterns(urlPatterns) 对所有请求都拦截，但是排除了 excludePathPatterns(excludes) 请求的拦截。
            registry.addInterceptor(new XssInterceptor()).
                    addPathPatterns(urlPatterns)
                    .excludePathPatterns(excludes).order(Ordered.LOWEST_PRECEDENCE);
        }
    }

    @Bean
    public Jackson2ObjectMapperBuilderCustomizer xssCustomizer() {
        return jacksonObjectMapperBuilder -> jacksonObjectMapperBuilder.deserializerByType(String.class,
                new XssDeserializer(xssProperties.getMode()));
    }
}

package com.jinw.cms.aspectj.annotation;

import java.lang.annotation.*;

@Documented
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.METHOD)
public @interface XssIgnore {

}

# 防止XSS攻击
xss:
  # 过滤开关
  enabled: true
  mode: clean