Instruction:
作为 Java 安全专家，检测此代码中的安全漏洞：
## 内容1
### 文件路径：
ethereum/api/src/main/java/org/hyperledger/besu/ethereum/api/jsonrpc/authentication/AuthenticationUtils.java
### 代码内容：
package org.hyperledger.besu.ethereum.api.jsonrpc.authentication;

import org.hyperledger.besu.ethereum.api.jsonrpc.internal.methods.JsonRpcMethod;

import java.util.Optional;
import java.util.concurrent.atomic.AtomicBoolean;

import com.google.common.annotations.VisibleForTesting;
import io.vertx.core.Handler;
import io.vertx.core.json.JsonObject;
import io.vertx.ext.auth.User;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;

public class AuthenticationUtils {
  private static final Logger LOG = LogManager.getLogger();

  @VisibleForTesting
  public static boolean isPermitted(
      final Optional<AuthenticationService> authenticationService,
      final Optional<User> optionalUser,
      final JsonRpcMethod jsonRpcMethod) {

    AtomicBoolean foundMatchingPermission = new AtomicBoolean();

    if (authenticationService.isPresent()) {
      if (optionalUser.isPresent()) {
        User user = optionalUser.get();
        for (String perm : jsonRpcMethod.getPermissions()) {
          user.isAuthorized(
              perm,
              (authed) -> {
                if (authed.result()) {
                  LOG.trace(
                      "user {} authorized : {} via permission {}",
                      user,
                      jsonRpcMethod.getName(),
                      perm);
                  foundMatchingPermission.set(true);
                }
              });
        }
      }
    } else {
      // no auth provider configured thus anything is permitted
      foundMatchingPermission.set(true);
    }

    if (!foundMatchingPermission.get()) {
      LOG.trace("user NOT authorized : {}", jsonRpcMethod.getName());
    }
    return foundMatchingPermission.get();
  }

  public static void getUser(
      final Optional<AuthenticationService> authenticationService,
      final String token,
      final Handler<Optional<User>> handler) {
    try {
      if (authenticationService.isEmpty()) {
        handler.handle(Optional.empty());
      } else {
        authenticationService
            .get()
            .getJwtAuthProvider()
            .authenticate(
                new JsonObject().put("jwt", token),
                (r) -> {
                  if (r.succeeded()) {
                    final Optional<User> user = Optional.ofNullable(r.result());
                    validateExpiryExists(user);
                    handler.handle(user);
                  } else {
                    LOG.debug("Invalid JWT token", r.cause());
                    handler.handle(Optional.empty());
                  }
                });
      }
    } catch (Exception e) {
      handler.handle(Optional.empty());
    }
  }

  private static void validateExpiryExists(final Optional<User> user) {
    if (!user.map(User::principal).map(p -> p.containsKey("exp")).orElse(false)) {
      throw new IllegalStateException("Invalid JWT doesn't have expiry");
    }
  }

  public static String getJwtTokenFromAuthorizationHeaderValue(final String value) {
    if (value != null) {
      final String bearerSchemaName = "Bearer ";
      if (value.startsWith(bearerSchemaName)) {
        return value.substring(bearerSchemaName.length());
      }
    }
    return null;
  }
}

## 内容2
### 文件路径：
ethereum/api/src/main/java/org/hyperledger/besu/ethereum/api/jsonrpc/internal/methods/JsonRpcMethod.java
### 代码内容：
package org.hyperledger.besu.ethereum.api.jsonrpc.internal.methods;

import org.hyperledger.besu.ethereum.api.jsonrpc.internal.JsonRpcRequestContext;
import org.hyperledger.besu.ethereum.api.jsonrpc.internal.response.JsonRpcResponse;

import java.util.ArrayList;
import java.util.List;

public interface JsonRpcMethod {

  /**
   * Standardised JSON-RPC method name.
   *
   * @return identification of the JSON-RPC method.
   */
  String getName();

  /**
   * Applies the method to given request.
   *
   * @param request input data for the JSON-RPC method.
   * @return output from applying the JSON-RPC method to the input.
   */
  JsonRpcResponse response(JsonRpcRequestContext request);

  /**
   * The list of Permissions that correspond to this JSON-RPC method. e.g. [net/*, net/listening]
   *
   * @return list of permissions that match this method.
   */
  default List<String> getPermissions() {
    List<String> permissions = new ArrayList<>();
    permissions.add("*:*");
    permissions.add(this.getName().replace('_', ':'));
    permissions.add(this.getName().substring(0, this.getName().indexOf('_')) + ":*");
    return permissions;
  };
}

Output:
【漏洞类型】路径遍历漏洞
【严重性】高
【漏洞摘要】原始代码中的路径遍历漏洞出现在`JsonRpcMethod`接口的`getPermissions()`方法中。该方法返回的权限列表中包含`this.getName().replace('_', ':')`和`this.getName().substring(0, this.getName().indexOf('_')) + ":*"`，这可能允许攻击者通过构造特定的JSON-RPC方法名称来绕过权限检查。具体来说，如果攻击者能够控制`JsonRpcMethod.getName()`的返回值，他们可能能够生成一个权限列表，该列表包含允许所有操作的通配符权限（*e:*），从而绕过安全限制。
【关键代码模式】
- `JsonRpcMethod.getName()`：用于获取JSON-RPC方法的名称。
- `this.getName().replace('_', ':')`：将方法名称中的下划线替换为冒号，生成一个新的权限字符串。
- `this.getName().substring(0, this.getName().indexOf('_')) + ":*"`：从方法名称中提取前缀，并附加通配符权限字符串。
- `user.isAuthorized()`：用于检查用户是否具有特定权限。
【修复方法说明】修复方法通过在找到匹配权限后立即返回，避免了不必要的权限检查，从而降低了绕过权限检查的风险。最佳实践是确保所有用户输入都经过严格验证，以防止攻击者通过构造特定的输入来绕过安全限制。


Instruction:
作为 Java 安全专家，检测此代码中的安全漏洞：
## 内容1
### 文件路径：
fusion-endpoint/src/main/java/com/vaadin/flow/server/connect/auth/VaadinConnectAccessChecker.java
### 代码内容：
package com.vaadin.flow.server.connect.auth;

import javax.annotation.security.DenyAll;
import javax.annotation.security.PermitAll;
import javax.annotation.security.RolesAllowed;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSession;
import java.lang.reflect.AnnotatedElement;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.vaadin.flow.server.VaadinService;

/**
 * Component used for checking role-based ACL in Vaadin Endpoints.
 *

 * For each request that is trying to access the method in the corresponding
 * Vaadin Endpoint, the permission check is carried on.
 *

 * It looks for {@link AnonymousAllowed} {@link PermitAll}, {@link DenyAll} and
 * {@link RolesAllowed} annotations in endpoint methods and classes containing
 * these methods (no super classes' annotations are taken into account).
 *

 * Method-level annotation override Class-level ones.
 *

 * In the next example, since the class is denied to all, method1 is not
 * accessible to anyone, method2 can be executed by any authorized used, method3
 * is only allowed to the accounts having the ROLE_USER authority and method4 is
 * available for every user, including anonymous ones that don't provide any
 * token in their requests.
 *
 *

 * @Endpoint
 * @DenyAll
 * public class DemoEndpoint {
 *
 *     public void method1() {
 *     }
 *
 *     @PermitAll
 *     public void method2() {
 *     }
 *
 *     @RolesAllowed("ROLE_USER")
 *     public void method3() {
 *     }
 *
 *     @AnonymousAllowed
 *     public void method4() {
 *     }
 * }
 *

 *
 */
public class VaadinConnectAccessChecker {

    private boolean xsrfProtectionEnabled = true;

    /**
     * Check that the endpoint is accessible for the current user.
     *
     * @param method
     *            the Vaadin endpoint method to check ACL
     * @return an error String with an issue description, if any validation
     *         issues occur, {@code null} otherwise
     * @param request
     *            the request that triggers the method invocation
     */
    public String check(Method method, HttpServletRequest request) {
        if (request.getUserPrincipal() != null) {
            return verifyAuthenticatedUser(method, request);
        } else {
            return verifyAnonymousUser(method, request);
        }
    }

    /**
     * Gets the entity to check for Vaadin endpoint security restrictions.
     *
     * @param method
     *            the method to analyze, not {@code null}
     * @return the entity that is responsible for security settings for the
     *         method passed
     * @throws IllegalArgumentException
     *             if the method is not public
     */
    public AnnotatedElement getSecurityTarget(Method method) {
        if (!Modifier.isPublic(method.getModifiers())) {
            throw new IllegalArgumentException(String.format(
                    "The method '%s' is not public hence cannot have a security target",
                    method));
        }
        return hasSecurityAnnotation(method) ? method
                : method.getDeclaringClass();
    }

    private String verifyAnonymousUser(Method method,
            HttpServletRequest request) {
        if (!getSecurityTarget(method)
                .isAnnotationPresent(AnonymousAllowed.class)
                || cannotAccessMethod(method, request)) {
            return "Anonymous access is not allowed";
        }
        return null;
    }

    private String verifyAuthenticatedUser(Method method,
            HttpServletRequest request) {
        if (cannotAccessMethod(method, request)) {
            return "Unauthorized access to Vaadin endpoint";
        }
        return null;
    }

    private boolean cannotAccessMethod(Method method,
            HttpServletRequest request) {
        return requestForbidden(request)
                || entityForbidden(getSecurityTarget(method), request);
    }

    private boolean requestForbidden(HttpServletRequest request) {
        if (!xsrfProtectionEnabled) {
            return false;
        }

        HttpSession session = request.getSession(false);
        if (session == null) {
            return false;
        }

        String csrfTokenInSession = (String) session
                .getAttribute(VaadinService.getCsrfTokenAttributeName());
        if (csrfTokenInSession == null) {
            if (getLogger().isInfoEnabled()) {
                getLogger().info(
                        "Unable to verify CSRF token for endpoint request, got null token in session");
            }

            return true;
        }

        if (!csrfTokenInSession.equals(request.getHeader("X-CSRF-Token"))) {
            if (getLogger().isInfoEnabled()) {
                getLogger().info("Invalid CSRF token in endpoint request");
            }

            return true;
        }

        return false;
    }

    private boolean entityForbidden(AnnotatedElement entity,
            HttpServletRequest request) {
        return entity.isAnnotationPresent(DenyAll.class) || (!entity
                .isAnnotationPresent(AnonymousAllowed.class)
                && !roleAllowed(entity.getAnnotation(RolesAllowed.class),
                        request));
    }

    private boolean roleAllowed(RolesAllowed rolesAllowed,
            HttpServletRequest request) {
        if (rolesAllowed == null) {
            return true;
        }

        for (String role : rolesAllowed.value()) {
            if (request.isUserInRole(role)) {
                return true;
            }
        }

        return false;
    }

    private boolean hasSecurityAnnotation(Method method) {
        return method.isAnnotationPresent(AnonymousAllowed.class)
                || method.isAnnotationPresent(PermitAll.class)
                || method.isAnnotationPresent(DenyAll.class)
                || method.isAnnotationPresent(RolesAllowed.class);
    }

    /**
     * Enable or disable XSRF token checking in endpoints.
     *
     * @param xsrfProtectionEnabled enable or disable protection.
     */
    public void enableCsrf(boolean xsrfProtectionEnabled) {
        this.xsrfProtectionEnabled = xsrfProtectionEnabled;
    }

    private static Logger getLogger() {
        return LoggerFactory.getLogger(VaadinConnectAccessChecker.class);
    }
}

Output:
【漏洞类型】信息泄露风险
【严重性】Medium
【漏洞摘要】原始代码在比较CSRF令牌时使用了String的equals方法，这会导致时间比较攻击。如果攻击者能够通过控制请求的时间响应来分析比较操作，他们可能能够推测出令牌的某些位，从而逐步猜测出整个令牌。
【关键代码模式】String.equals(), 不安全的字符串比较，CSRF令牌的比较。
【修复方法说明】修复方法使用MessageDigest.isEqual()来代替String.equals()进行时间恒定的比较，防止时间比较攻击。


Instruction:
作为 Java 安全专家，检测此代码中的安全漏洞：
## 内容1
### 文件路径：
flow-server/src/main/java/com/vaadin/flow/server/StaticFileServer.java
### 代码内容：
package com.vaadin.flow.server;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.net.URLConnection;
import java.util.regex.Pattern;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.vaadin.flow.function.DeploymentConfiguration;
import com.vaadin.flow.internal.ResponseWriter;

import static com.vaadin.flow.server.Constants.VAADIN_BUILD_FILES_PATH;
import static com.vaadin.flow.server.Constants.VAADIN_MAPPING;
import static com.vaadin.flow.shared.ApplicationConstants.VAADIN_STATIC_FILES_PATH;

/**
 * Handles sending of resources from the WAR root (web content) or
 * META-INF/resources in the case that {@link VaadinServlet} is mapped using
 * "/*".
 *

 * This class is primarily meant to be used during developing time. For a
 * production mode site you should consider serving static resources directly
 * from the servlet (using a default servlet if such exists) or through a stand
 * alone static file server.
 *
 * @author Vaadin Ltd
 * @since 1.0
 */
public class StaticFileServer implements StaticFileHandler {
    static final String PROPERTY_FIX_INCORRECT_WEBJAR_PATHS = Constants.VAADIN_PREFIX
            + "fixIncorrectWebjarPaths";
    private static final Pattern INCORRECT_WEBJAR_PATH_REGEX = Pattern
            .compile("^/frontend[-\\w/]*/webjars/");

    private final ResponseWriter responseWriter;
    private final VaadinServletService servletService;
    private DeploymentConfiguration deploymentConfiguration;

    /**
     * Constructs a file server.
     *
     * @param servletService
     *            servlet service for the deployment, not null
     */
    public StaticFileServer(VaadinServletService servletService) {
        this.servletService = servletService;
        deploymentConfiguration = servletService.getDeploymentConfiguration();
        responseWriter = new ResponseWriter(deploymentConfiguration);
    }

    @Override
    public boolean isStaticResourceRequest(HttpServletRequest request) {
        URL resource;

        String requestFilename = getRequestFilename(request);
        if (requestFilename.endsWith("/")) {
            // Directories are not static resources although
            // servletContext.getResource will return a URL for them, at
            // least with Jetty
            return false;
        }

        if (requestFilename.startsWith("/" + VAADIN_STATIC_FILES_PATH)
                || requestFilename.startsWith("/" + VAADIN_BUILD_FILES_PATH)) {
            // The path is reserved for internal resources only
            // We rather serve 404 than let it fall through
            return true;
        }
        resource = servletService.getStaticResource(requestFilename);

        if (resource == null && shouldFixIncorrectWebjarPaths()
                && isIncorrectWebjarPath(requestFilename)) {
            // Flow issue #4601
            return true;
        }

        return resource != null;
    }

    @Override
    public boolean serveStaticResource(HttpServletRequest request,
            HttpServletResponse response) throws IOException {

        String filenameWithPath = getRequestFilename(request);
        if (HandlerHelper.isPathUnsafe(filenameWithPath)) {
            getLogger().info(HandlerHelper.UNSAFE_PATH_ERROR_MESSAGE_PATTERN,
                    filenameWithPath);
            response.setStatus(HttpServletResponse.SC_FORBIDDEN);
            return true;
        }

        URL resourceUrl = null;
        if (isAllowedVAADINBuildUrl(filenameWithPath)) {
            resourceUrl = servletService.getClassLoader()
                    .getResource("META-INF" + filenameWithPath);
        }
        if (resourceUrl == null) {
            resourceUrl = servletService.getStaticResource(filenameWithPath);
        }
        if (resourceUrl == null && shouldFixIncorrectWebjarPaths()
                && isIncorrectWebjarPath(filenameWithPath)) {
            // Flow issue #4601
            resourceUrl = servletService.getStaticResource(
                    fixIncorrectWebjarPath(filenameWithPath));
        }

        if (resourceUrl == null) {
            // Not found in webcontent or in META-INF/resources in some JAR
            response.sendError(HttpServletResponse.SC_NOT_FOUND);
            return true;
        }

        // There is a resource!

        // Intentionally writing cache headers also for 304 responses
        writeCacheHeaders(filenameWithPath, response);

        long timestamp = writeModificationTimestamp(resourceUrl, request,
                response);
        if (browserHasNewestVersion(request, timestamp)) {
            // Browser is up to date, nothing further to do than set the
            // response code
            response.setStatus(HttpServletResponse.SC_NOT_MODIFIED);
            return true;
        }
        responseWriter.writeResponseContents(filenameWithPath, resourceUrl,
                request, response);
        return true;
    }

    // When referring to webjar resources from application stylesheets (loaded
    // using @StyleSheet) using relative paths, the paths will be different in
    // development mode and in production mode. The reason is that in production
    // mode, the CSS is incorporated into the bundle and when this happens,
    // the relative paths are changed so that they end up pointing to paths like
    // 'frontend-es6/webjars' instead of just 'webjars'.

    // There is a similar problem when referring to webjar resources from
    // application stylesheets inside HTML custom styles (loaded using
    // @HtmlImport). In this case, the paths will also be changed in production.
    // For example, if the HTML file resides in 'frontend/styles' and refers to
    // 'webjars/foo', the path will be changed to refer to
    // 'frontend/styles/webjars/foo', which is incorrect. You could add '../../'
    // to the path in the HTML file but then it would not work in development
    // mode.

    // These paths are changed deep inside the Polymer build chain. It was
    // easier to fix the StaticFileServer to take the incorrect path names
    // into account than fixing the Polymer build chain to generate correct
    // paths. Hence, these methods:

    private boolean shouldFixIncorrectWebjarPaths() {
        return deploymentConfiguration.isProductionMode()
                && deploymentConfiguration.getBooleanProperty(
                        PROPERTY_FIX_INCORRECT_WEBJAR_PATHS, false);
    }

    private boolean isIncorrectWebjarPath(String requestFilename) {
        return INCORRECT_WEBJAR_PATH_REGEX.matcher(requestFilename).lookingAt();
    }

    private String fixIncorrectWebjarPath(String requestFilename) {
        return INCORRECT_WEBJAR_PATH_REGEX.matcher(requestFilename)
                .replaceAll("/webjars/");
    }

    /**
     * Check if it is ok to serve the requested file from the classpath.
     *

     * ClassLoader is applicable for use when we are in NPM mode and are serving
     * from the VAADIN/build folder with no folder changes in path.
     *
     * @param filenameWithPath
     *            requested filename containing path
     * @return true if we are ok to try serving the file
     */
    private boolean isAllowedVAADINBuildUrl(String filenameWithPath) {
        if (deploymentConfiguration.isCompatibilityMode()) {
            getLogger().trace(
                    "Serving from the classpath in legacy "
                            + "mode is not accepted. "
                            + "Letting request for '{}' go to servlet context.",
                    filenameWithPath);
            return false;
        }

        // Check that we target VAADIN/build
        return filenameWithPath.startsWith("/" + VAADIN_BUILD_FILES_PATH);
    }

    /**
     * Writes the modification timestamp info for the file into the response.
     *
     * @param resourceUrl
     *            the internal URL of the file
     * @param request
     *            the request object
     * @param response
     *            the response object
     * @return the written timestamp or -1 if no timestamp was written
     */
    protected long writeModificationTimestamp(URL resourceUrl,
            HttpServletRequest request, HttpServletResponse response) {
        // Find the modification timestamp
        long lastModifiedTime;
        URLConnection connection = null;
        try {
            connection = resourceUrl.openConnection();
            lastModifiedTime = connection.getLastModified();
            // Remove milliseconds to avoid comparison problems (milliseconds
            // are not returned by the browser in the "If-Modified-Since"
            // header).
            lastModifiedTime = lastModifiedTime - lastModifiedTime % 1000;
            response.setDateHeader("Last-Modified", lastModifiedTime);
            return lastModifiedTime;
        } catch (Exception e) {
            getLogger().trace(
                    "Failed to find out last modified timestamp. Continuing without it.",
                    e);
        } finally {
            try {
                // Explicitly close the input stream to prevent it
                // from remaining hanging
                // http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4257700
                if (connection != null) {
                    InputStream is = connection.getInputStream();
                    if (is != null) {
                        is.close();
                    }
                }
            } catch (IOException e) {
                getLogger().warn("Error closing URLConnection input stream", e);
            }
        }
        return -1L;
    }

    /**
     * Writes cache headers for the file into the response.
     *
     * @param filenameWithPath
     *            the name and path of the file being sent
     * @param response
     *            the response object
     */
    protected void writeCacheHeaders(String filenameWithPath,
            HttpServletResponse response) {
        int resourceCacheTime = getCacheTime(filenameWithPath);
        String cacheControl;
        if (!deploymentConfiguration.isProductionMode()) {
            cacheControl = "no-cache";
        } else if (resourceCacheTime > 0) {
            cacheControl = "max-age=" + resourceCacheTime;
        } else {
            cacheControl = "public, max-age=0, must-revalidate";
        }
        response.setHeader("Cache-Control", cacheControl);
    }

    /**
     * Returns the (decoded) requested file name, relative to the context path.
     *

     * Package private for testing purposes.
     *
     * @param request
     *            the request object
     * @return the requested file name, starting with a {@literal /}
     */
    String getRequestFilename(HttpServletRequest request) {
        // http://localhost:8888/context/servlet/folder/file.js
        // ->
        // /servlet/folder/file.js
        //
        // http://localhost:8888/context/servlet/VAADIN/folder/file.js
        // ->
        // /VAADIN/folder/file.js
        if (request.getPathInfo() == null) {
            return request.getServletPath();
        } else if (request.getPathInfo().startsWith("/" + VAADIN_MAPPING)) {
            return request.getPathInfo();
        }
        return request.getServletPath() + request.getPathInfo();
    }

    /**
     * Calculates the cache lifetime for the given filename in seconds.
     *

     * By default filenames containing ".nocache." return 0, filenames
     * containing ".cache." return one year and all other files return 1 hour.
     *
     * @param filenameWithPath
     *            the name of the file being sent
     * @return cache lifetime for the given filename in seconds
     */
    protected int getCacheTime(String filenameWithPath) {
        /*
         * GWT conventions:
         *
         * - files containing .nocache. will not be cached.
         *
         * - files containing .cache. will be cached for one year.
         *
         * https://developers.google.com/web-toolkit/doc/latest/
         * DevGuideCompilingAndDebugging#perfect_caching
         */
        if (filenameWithPath.contains(".nocache.")) {
            return 0;
        }
        if (filenameWithPath.contains(".cache.")) {
            return 60 * 60 * 24 * 365;
        }
        /*
         * For all other files, the browser is allowed to cache for 1 hour
         * without checking if the file has changed.
         */
        return 3600;
    }

    /**
     * Checks if the browser has an up to date cached version of requested
     * resource using the "If-Modified-Since" header.
     *
     * @param request
     *            The HttpServletRequest from the browser.
     * @param resourceLastModifiedTimestamp
     *            The timestamp when the resource was last modified. -1 if the
     *            last modification time is unknown.
     * @return true if the If-Modified-Since header tells the cached version in
     *         the browser is up to date, false otherwise
     */
    protected boolean browserHasNewestVersion(HttpServletRequest request,
            long resourceLastModifiedTimestamp) {
        assert resourceLastModifiedTimestamp >= -1L;

        if (resourceLastModifiedTimestamp == -1L) {
            // We do not know when it was modified so the browser cannot have an
            // up-to-date version
            return false;
        }
        /*
         * The browser can request the resource conditionally using an
         * If-Modified-Since header. Check this against the last modification
         * time.
         */
        try {
            // If-Modified-Since represents the timestamp of the version cached
            // in the browser
            long headerIfModifiedSince = request
                    .getDateHeader("If-Modified-Since");

            if (headerIfModifiedSince >= resourceLastModifiedTimestamp) {
                // Browser has this an up-to-date version of the resource
                return true;
            }
        } catch (Exception e) {
            // Failed to parse header.
            getLogger().trace("Unable to parse If-Modified-Since", e);
        }
        return false;
    }

    private static Logger getLogger() {
        return LoggerFactory.getLogger(StaticFileServer.class.getName());
    }

}

Output:
【漏洞类型】路径遍历漏洞
【严重性】High
【漏洞摘要】此代码存在路径遍历漏洞，因为它使用用户输入的文件路径来查找和提供静态资源。具体表现为在`serveStaticResource`方法中，`filenameWithPath`变量直接从用户请求中获取，并用于查找资源。如果攻击者能够操纵这个路径，他们可能能够访问未授权的文件。
【关键代码模式】`getRequestFilename`方法、`serveStaticResource`方法中的`filenameWithPath`变量。
【修复方法说明】修复方法通过引入`OSGiAccess`类和`getStaticResource`方法，避免在OSGi环境中通过`ServletContext`暴露静态资源。最佳实践是避免在用户输入直接控制的基础路径上查找文件，并对用户输入进行严格的路径验证和限制。


Instruction:
作为 Java 安全专家，检测此代码中的安全漏洞：
## 内容1
### 文件路径：
flow-server/src/main/java/com/vaadin/flow/di/LookupInitializer.java
### 代码内容：
package com.vaadin.flow.di;

import javax.servlet.ServletException;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Objects;
import java.util.ServiceLoader;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
import java.util.function.BiFunction;
import java.util.stream.Collectors;

import org.apache.commons.io.IOUtils;

import com.vaadin.flow.component.page.AppShellConfigurator;
import com.vaadin.flow.function.VaadinApplicationInitializationBootstrap;
import com.vaadin.flow.internal.ReflectTools;
import com.vaadin.flow.server.VaadinContext;
import com.vaadin.flow.server.startup.AppShellPredicate;
import com.vaadin.flow.server.startup.ApplicationConfigurationFactory;
import com.vaadin.flow.server.startup.DefaultApplicationConfigurationFactory;

/**
 * Default implementation of {@link AbstractLookupInitializer}.
 *
 * @author Vaadin Ltd
 * @since
 *
 * @see AbstractLookupInitializer
 */
public class LookupInitializer implements AbstractLookupInitializer {

    protected static final String SPI = " SPI: ";

    protected static final String ONE_IMPL_REQUIRED = ". Only one implementation should be registered. "
            + "Use lookupAll to get all instances of the given type.";

    protected static final String SEVERAL_IMPLS = "Found several implementations in the classpath for ";

    /**
     * Default implementation of {@link Lookup}.
     *
     * @author Vaadin Ltd
     * @since
     *
     */
    protected static class LookupImpl implements Lookup {

        protected final Map<Class<?>, Collection<Object>> serviceMap;

        /**
         * Creates a new instance of {@link Lookup} with services found in the
         * application classpath.
         *
         * @param initialServices
         *            map of initial services with their implementations
         * @param factory
         *            a factory to create a service object instance
         */
        protected LookupImpl(
                Map<Class<?>, Collection<Class<?>>> initialServices,
                BiFunction<Class<?>, Class<?>, Object> factory) {
            serviceMap = new HashMap<>();
            initialServices.forEach((serviceClass,
                    impls) -> serviceMap.put(serviceClass, impls.stream()
                            .map(impl -> factory.apply(serviceClass, impl))
                            .filter(Objects::nonNull)
                            .collect(Collectors.toList())));
        }

        @Override
        public <T> T lookup(Class<T> serviceClass) {
            Collection<Object> registered = serviceMap.get(serviceClass);
            if (registered == null || registered.isEmpty()) {
                ServiceLoader<T> loader = ServiceLoader.load(serviceClass);
                List<T> services = new ArrayList<>();
                for (Iterator<T> iterator = loader.iterator(); iterator
                        .hasNext();) {
                    services.add(iterator.next());
                }
                if (services.size() > 1) {
                    throw new IllegalStateException(SEVERAL_IMPLS + serviceClass
                            + SPI + services + ONE_IMPL_REQUIRED);
                } else if (services.size() == 1) {
                    return services.get(0);
                }
                return null;
            } else if (registered.size() > 1) {
                throw new IllegalStateException(SEVERAL_IMPLS + serviceClass
                        + SPI + registered + ONE_IMPL_REQUIRED);
            } else {
                return serviceClass.cast(registered.iterator().next());
            }
        }

        @Override
        public <T> Collection<T> lookupAll(Class<T> serviceClass) {
            List<T> result = new ArrayList<>();
            Collection<Object> registered = serviceMap.get(serviceClass);

            Set<?> registeredClasses = registered == null
                    ? Collections.emptySet()
                    : registered.stream().map(Object::getClass)
                            .collect(Collectors.toSet());
            if (registered != null) {
                registered.forEach(
                        service -> result.add(serviceClass.cast(service)));
            }
            ServiceLoader<T> loader = ServiceLoader.load(serviceClass);
            for (Iterator<T> iterator = loader.iterator(); iterator
                    .hasNext();) {
                T next = iterator.next();
                if (!registeredClasses.contains(next.getClass())) {
                    result.add(next);
                }
            }
            return result;
        }

    }

    /**
     * Default implementation of {@link ResourceProvider}.
     *
     * @author Vaadin Ltd
     * @since
     *
     */
    protected static class ResourceProviderImpl implements ResourceProvider {

        private Map<String, CachedStreamData> cache = new ConcurrentHashMap<>();

        /**
         * Creates a new instance.
         */
        public ResourceProviderImpl() {
        }

        @Override
        public URL getApplicationResource(String path) {
            return ResourceProviderImpl.class.getClassLoader()
                    .getResource(path);
        }

        @Override
        public List<URL> getApplicationResources(String path)
                throws IOException {
            return Collections.list(ResourceProviderImpl.class.getClassLoader()
                    .getResources(path));
        }

        @Override
        public URL getClientResource(String path) {
            return getApplicationResource(path);
        }

        @Override
        public InputStream getClientResourceAsStream(String path)
                throws IOException {
            // the client resource should be available in the classpath, so
            // its content is cached once. If an exception is thrown then
            // something is broken and it's also cached and will be rethrown on
            // every subsequent access
            CachedStreamData cached = cache.computeIfAbsent(path, key -> {
                URL url = getClientResource(key);
                try (InputStream stream = url.openStream()) {
                    ByteArrayOutputStream tempBuffer = new ByteArrayOutputStream();
                    IOUtils.copy(stream, tempBuffer);
                    return new CachedStreamData(tempBuffer.toByteArray(), null);
                } catch (IOException e) {
                    return new CachedStreamData(null, e);
                }
            });

            IOException exception = cached.exception;
            if (exception == null) {
                return new ByteArrayInputStream(cached.data);
            }
            throw exception;
        }

    }

    private static class RegularOneTimeInitializerPredicate
            implements OneTimeInitializerPredicate {

        @Override
        public boolean runOnce() {
            return true;
        }

    }

    /**
     * Default implementation of {@link AppShellPredicate}.
     *
     * @author Vaadin Ltd
     * @since
     *
     */
    protected static class AppShellPredicateImpl implements AppShellPredicate {

        /**
         * Creates a new instance.
         */
        public AppShellPredicateImpl() {
        }

        @Override
        public boolean isShell(Class<?> clz) {
            return AppShellConfigurator.class.isAssignableFrom(clz);
        }
    }

    private static class CachedStreamData {

        private final byte[] data;
        private final IOException exception;

        private CachedStreamData(byte[] data, IOException exception) {
            this.data = data;
            this.exception = exception;
        }
    }

    @Override
    public void initialize(VaadinContext context,
            Map<Class<?>, Collection<Class<?>>> services,
            VaadinApplicationInitializationBootstrap bootstrap)
            throws ServletException {
        services.put(OneTimeInitializerPredicate.class, Collections
                .singleton(RegularOneTimeInitializerPredicate.class));
        ensureService(services, ResourceProvider.class,
                ResourceProviderImpl.class);
        ensureService(services, AppShellPredicate.class,
                AppShellPredicateImpl.class);
        ensureService(services, ApplicationConfigurationFactory.class,
                DefaultApplicationConfigurationFactory.class);
        bootstrap.bootstrap(createLookup(context, services));
    }

    /**
     * Creates a lookup based on provided {@code services}.
     *
     * @param context
     *            a Vaadin context to create a lookup for
     *
     * @param services
     *            the service objects mapped to the service type to create a
     *            lookup
     * @return the lookup instance created with provided services
     */
    protected Lookup createLookup(VaadinContext context,
            Map<Class<?>, Collection<Class<?>>> services) {
        return new LookupImpl(services, this::instantiate);
    }

    /**
     * Ensures that provided {@code services} contain implementation for
     * {@code serviceType} SPI.
     *

     * The default {@code  serviceImpl} implementation will be set as the
     * service into {@code services} if there is no other services available.
     *
     * @param services
     *            map of internal services
     * @param serviceType
     *            SPI type
     * @param serviceImpl
     *            the default SPI implementation
     */
    protected <T> void ensureService(
            Map<Class<?>, Collection<Class<?>>> services, Class<T> serviceType,
            Class<? extends T> serviceImpl) {
        Collection<Class<?>> impls = services.get(serviceType);
        if (impls == null) {
            impls = Collections.emptyList();
        }
        impls = impls.stream().filter(clazz -> !clazz.equals(serviceImpl))
                .collect(Collectors.toList());
        if (impls.isEmpty()) {
            services.put(serviceType, Collections.singletonList(serviceImpl));
        } else if (impls.size() > 1) {
            throw new IllegalStateException(
                    SEVERAL_IMPLS + serviceType.getSimpleName() + SPI + impls
                            + ONE_IMPL_REQUIRED);
        } else {
            services.put(serviceType, impls);
        }
    }

    /**
     * Instantiates service {@code implementation} type with the given
     * {@code serviceClass} .
     *
     * @param <T>
     *            service type
     * @param serviceClass
     *            service class
     * @param implementation
     *            service implementation class
     * @return an instantiated service implementation object
     */
    protected <T> T instantiate(Class<T> serviceClass,
            Class<?> implementation) {
        if (RegularOneTimeInitializerPredicate.class.equals(implementation)) {
            return serviceClass.cast(new RegularOneTimeInitializerPredicate());
        }
        return serviceClass.cast(ReflectTools.createInstance(implementation));
    }

}

## 内容2
### 文件路径：
flow-server/src/main/java/com/vaadin/flow/server/StaticFileServer.java
### 代码内容：
package com.vaadin.flow.server;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.net.URLConnection;
import java.util.ArrayList;
import java.util.List;
import java.util.regex.Pattern;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.vaadin.flow.function.DeploymentConfiguration;
import com.vaadin.flow.internal.ResponseWriter;
import com.vaadin.flow.server.frontend.FrontendUtils;

import static com.vaadin.flow.server.Constants.VAADIN_BUILD_FILES_PATH;
import static com.vaadin.flow.server.Constants.VAADIN_MAPPING;
import static com.vaadin.flow.server.Constants.VAADIN_WEBAPP_RESOURCES;
import static com.vaadin.flow.shared.ApplicationConstants.VAADIN_STATIC_FILES_PATH;

/**
 * Handles sending of resources from the WAR root (web content) or
 * META-INF/resources in the case that {@link VaadinServlet} is mapped using
 * "/*".
 *

 * This class is primarily meant to be used during developing time. For a
 * production mode site you should consider serving static resources directly
 * from the servlet (using a default servlet if such exists) or through a stand
 * alone static file server.
 *
 * @author Vaadin Ltd
 * @since 1.0
 */
public class StaticFileServer implements StaticFileHandler {
    static final String PROPERTY_FIX_INCORRECT_WEBJAR_PATHS = Constants.VAADIN_PREFIX
            + "fixIncorrectWebjarPaths";
    private static final Pattern INCORRECT_WEBJAR_PATH_REGEX = Pattern
            .compile("^/frontend[-\\w/]*/webjars/");

    private final ResponseWriter responseWriter;
    private final VaadinService vaadinService;
    private DeploymentConfiguration deploymentConfiguration;
    private final List<String> manifestPaths;

    // Matcher to match string starting with '/themes/[theme-name]/'
    protected static final Pattern APP_THEME_PATTERN = Pattern
        .compile("^\\/themes\\/[\\s\\S]+?\\/");

    /**
     * Constructs a file server.
     *
     * @param vaadinService
     *            vaadin service for the deployment, not null
     */
    public StaticFileServer(VaadinService vaadinService) {
        this.vaadinService = vaadinService;
        deploymentConfiguration = vaadinService.getDeploymentConfiguration();
        responseWriter = new ResponseWriter(deploymentConfiguration);
        manifestPaths = getManifestPathsFromJson();
    }

    @Override
    public boolean isStaticResourceRequest(HttpServletRequest request) {
        URL resource;

        String requestFilename = getRequestFilename(request);
        if (requestFilename.endsWith("/")) {
            // Directories are not static resources although
            // servletContext.getResource will return a URL for them, at
            // least with Jetty
            return false;
        }

        if (APP_THEME_PATTERN.matcher(requestFilename).find() || requestFilename
            .startsWith("/" + VAADIN_STATIC_FILES_PATH) || requestFilename
            .startsWith("/" + VAADIN_BUILD_FILES_PATH)) {
            // The path is reserved for internal resources only
            // We rather serve 404 than let it fall through
            return true;
        }

        if (manifestPaths.contains(requestFilename)) {
            // The path is on the webpack manifest list, so it is a static
            // resource as well.
            return true;
        }
        resource = vaadinService.getStaticResource(requestFilename);

        if (resource == null && shouldFixIncorrectWebjarPaths()
                && isIncorrectWebjarPath(requestFilename)) {
            // Flow issue #4601
            return true;
        }

        return resource != null;
    }

    @Override
    public boolean serveStaticResource(HttpServletRequest request,
            HttpServletResponse response) throws IOException {

        String filenameWithPath = getRequestFilename(request);
        if (HandlerHelper.isPathUnsafe(filenameWithPath)) {
            getLogger().info(HandlerHelper.UNSAFE_PATH_ERROR_MESSAGE_PATTERN,
                    filenameWithPath);
            response.setStatus(HttpServletResponse.SC_FORBIDDEN);
            return true;
        }

        URL resourceUrl = null;
        if (isAllowedVAADINBuildOrStaticUrl(filenameWithPath)
                || manifestPaths.contains(filenameWithPath)) {
            if(APP_THEME_PATTERN.matcher(filenameWithPath).find()) {
                resourceUrl = vaadinService.getClassLoader()
                    .getResource(VAADIN_WEBAPP_RESOURCES + "VAADIN/static/"
                            + filenameWithPath.replaceFirst("^/", ""));

            } else {
                resourceUrl = vaadinService.getClassLoader()
                    .getResource(VAADIN_WEBAPP_RESOURCES
                            + filenameWithPath.replaceFirst("^/", ""));

            }
        }
        if (resourceUrl == null) {
            resourceUrl = vaadinService.getStaticResource(filenameWithPath);
        }
        if (resourceUrl == null && shouldFixIncorrectWebjarPaths()
                && isIncorrectWebjarPath(filenameWithPath)) {
            // Flow issue #4601
            resourceUrl = vaadinService.getStaticResource(
                    fixIncorrectWebjarPath(filenameWithPath));
        }

        if (resourceUrl == null) {
            // Not found in webcontent or in META-INF/resources in some JAR
            response.sendError(HttpServletResponse.SC_NOT_FOUND);
            return true;
        }

        // There is a resource!

        // Intentionally writing cache headers also for 304 responses
        writeCacheHeaders(filenameWithPath, response);

        long timestamp = writeModificationTimestamp(resourceUrl, request,
                response);
        if (browserHasNewestVersion(request, timestamp)) {
            // Browser is up to date, nothing further to do than set the
            // response code
            response.setStatus(HttpServletResponse.SC_NOT_MODIFIED);
            return true;
        }
        responseWriter.writeResponseContents(filenameWithPath, resourceUrl,
                request, response);
        return true;
    }

    // When referring to webjar resources from application stylesheets (loaded
    // using @StyleSheet) using relative paths, the paths will be different in
    // development mode and in production mode. The reason is that in production
    // mode, the CSS is incorporated into the bundle and when this happens,
    // the relative paths are changed so that they end up pointing to paths like
    // 'frontend-es6/webjars' instead of just 'webjars'.

    // There is a similar problem when referring to webjar resources from
    // application stylesheets inside HTML custom styles (loaded using
    // @HtmlImport). In this case, the paths will also be changed in production.
    // For example, if the HTML file resides in 'frontend/styles' and refers to
    // 'webjars/foo', the path will be changed to refer to
    // 'frontend/styles/webjars/foo', which is incorrect. You could add '../../'
    // to the path in the HTML file but then it would not work in development
    // mode.

    // These paths are changed deep inside the Polymer build chain. It was
    // easier to fix the StaticFileServer to take the incorrect path names
    // into account than fixing the Polymer build chain to generate correct
    // paths. Hence, these methods:

    private boolean shouldFixIncorrectWebjarPaths() {
        return deploymentConfiguration.isProductionMode()
                && deploymentConfiguration.getBooleanProperty(
                        PROPERTY_FIX_INCORRECT_WEBJAR_PATHS, false);
    }

    private boolean isIncorrectWebjarPath(String requestFilename) {
        return INCORRECT_WEBJAR_PATH_REGEX.matcher(requestFilename).lookingAt();
    }

    private String fixIncorrectWebjarPath(String requestFilename) {
        return INCORRECT_WEBJAR_PATH_REGEX.matcher(requestFilename)
                .replaceAll("/webjars/");
    }

    /**
     * Check if it is ok to serve the requested file from the classpath.
     *

     * ClassLoader is applicable for use when we are in NPM mode and are serving
     * from the VAADIN/build folder with no folder changes in path.
     *
     * @param filenameWithPath
     *            requested filename containing path
     * @return true if we are ok to try serving the file
     */
    private boolean isAllowedVAADINBuildOrStaticUrl(String filenameWithPath) {
        // Check that we target VAADIN/build | VAADIN/static | themes/theme-name
        return filenameWithPath.startsWith("/" + VAADIN_BUILD_FILES_PATH)
            || filenameWithPath.startsWith("/" + VAADIN_STATIC_FILES_PATH)
            || APP_THEME_PATTERN.matcher(filenameWithPath).find();
    }

    /**
     * Writes the modification timestamp info for the file into the response.
     *
     * @param resourceUrl
     *            the internal URL of the file
     * @param request
     *            the request object
     * @param response
     *            the response object
     * @return the written timestamp or -1 if no timestamp was written
     */
    protected long writeModificationTimestamp(URL resourceUrl,
            HttpServletRequest request, HttpServletResponse response) {
        // Find the modification timestamp
        long lastModifiedTime;
        URLConnection connection = null;
        try {
            connection = resourceUrl.openConnection();
            lastModifiedTime = connection.getLastModified();
            // Remove milliseconds to avoid comparison problems (milliseconds
            // are not returned by the browser in the "If-Modified-Since"
            // header).
            lastModifiedTime = lastModifiedTime - lastModifiedTime % 1000;
            response.setDateHeader("Last-Modified", lastModifiedTime);
            return lastModifiedTime;
        } catch (Exception e) {
            getLogger().trace(
                    "Failed to find out last modified timestamp. Continuing without it.",
                    e);
        } finally {
            try {
                // Explicitly close the input stream to prevent it
                // from remaining hanging
                // http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4257700
                if (connection != null) {
                    InputStream is = connection.getInputStream();
                    if (is != null) {
                        is.close();
                    }
                }
            } catch (IOException e) {
                getLogger().warn("Error closing URLConnection input stream", e);
            }
        }
        return -1L;
    }

    /**
     * Writes cache headers for the file into the response.
     *
     * @param filenameWithPath
     *            the name and path of the file being sent
     * @param response
     *            the response object
     */
    protected void writeCacheHeaders(String filenameWithPath,
            HttpServletResponse response) {
        int resourceCacheTime = getCacheTime(filenameWithPath);
        String cacheControl;
        if (!deploymentConfiguration.isProductionMode()) {
            cacheControl = "no-cache";
        } else if (resourceCacheTime > 0) {
            cacheControl = "max-age=" + resourceCacheTime;
        } else {
            cacheControl = "public, max-age=0, must-revalidate";
        }
        response.setHeader("Cache-Control", cacheControl);
    }

    /**
     * Returns the (decoded) requested file name, relative to the context path.
     *

     * Package private for testing purposes.
     *
     * @param request
     *            the request object
     * @return the requested file name, starting with a {@literal /}
     */
    String getRequestFilename(HttpServletRequest request) {
        // http://localhost:8888/context/servlet/folder/file.js
        // ->
        // /servlet/folder/file.js
        //
        // http://localhost:8888/context/servlet/VAADIN/folder/file.js
        // ->
        // /VAADIN/folder/file.js
        if (request.getPathInfo() == null) {
            return request.getServletPath();
        } else if (request.getPathInfo().startsWith("/" + VAADIN_MAPPING)
            || APP_THEME_PATTERN.matcher(request.getPathInfo()).find()) {
            return request.getPathInfo();
        }
        return request.getServletPath() + request.getPathInfo();
    }

    /**
     * Calculates the cache lifetime for the given filename in seconds.
     *

     * By default filenames containing ".nocache." return 0, filenames
     * containing ".cache." return one year and all other files return 1 hour.
     *
     * @param filenameWithPath
     *            the name of the file being sent
     * @return cache lifetime for the given filename in seconds
     */
    protected int getCacheTime(String filenameWithPath) {
        /*
         * GWT conventions:
         *
         * - files containing .nocache. will not be cached.
         *
         * - files containing .cache. will be cached for one year.
         *
         * https://developers.google.com/web-toolkit/doc/latest/
         * DevGuideCompilingAndDebugging#perfect_caching
         */
        if (filenameWithPath.contains(".nocache.")) {
            return 0;
        }
        if (filenameWithPath.contains(".cache.")) {
            return 60 * 60 * 24 * 365;
        }
        /*
         * For all other files, the browser is allowed to cache for 1 hour
         * without checking if the file has changed.
         */
        return 3600;
    }

    /**
     * Checks if the browser has an up to date cached version of requested
     * resource using the "If-Modified-Since" header.
     *
     * @param request
     *            The HttpServletRequest from the browser.
     * @param resourceLastModifiedTimestamp
     *            The timestamp when the resource was last modified. -1 if the
     *            last modification time is unknown.
     * @return true if the If-Modified-Since header tells the cached version in
     *         the browser is up to date, false otherwise
     */
    protected boolean browserHasNewestVersion(HttpServletRequest request,
            long resourceLastModifiedTimestamp) {
        assert resourceLastModifiedTimestamp >= -1L;

        if (resourceLastModifiedTimestamp == -1L) {
            // We do not know when it was modified so the browser cannot have an
            // up-to-date version
            return false;
        }
        /*
         * The browser can request the resource conditionally using an
         * If-Modified-Since header. Check this against the last modification
         * time.
         */
        try {
            // If-Modified-Since represents the timestamp of the version cached
            // in the browser
            long headerIfModifiedSince = request
                    .getDateHeader("If-Modified-Since");

            if (headerIfModifiedSince >= resourceLastModifiedTimestamp) {
                // Browser has this an up-to-date version of the resource
                return true;
            }
        } catch (Exception e) {
            // Failed to parse header.
            getLogger().trace("Unable to parse If-Modified-Since", e);
        }
        return false;
    }

    /**
     * Load manifest.json, if exists, and extract manifest paths.
     *
     * In development mode, this resource does not exist, an empty list is
     * returned in that case.
     *
     * @return list of paths mapped to static webapp resources, or empty list
     */
    private List<String> getManifestPathsFromJson() {
        InputStream stream = vaadinService.getClassLoader()
                .getResourceAsStream(
                        VAADIN_WEBAPP_RESOURCES + "manifest.json");
        if (stream == null) {
            // manifest.json resource does not exist, probably dev mode
            return new ArrayList<>();
        }

        return FrontendUtils
                .parseManifestPaths(FrontendUtils.streamToString(stream));
    }

    private static Logger getLogger() {
        return LoggerFactory.getLogger(StaticFileServer.class.getName());
    }

}

## 内容3
### 文件路径：
flow-server/src/main/java/com/vaadin/flow/server/VaadinServlet.java
### 代码内容：
package com.vaadin.flow.server;

import javax.servlet.ServletConfig;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import java.io.IOException;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.Properties;

import com.vaadin.flow.component.UI;
import com.vaadin.flow.di.Lookup;
import com.vaadin.flow.function.DeploymentConfiguration;
import com.vaadin.flow.internal.ApplicationClassLoaderAccess;
import com.vaadin.flow.internal.CurrentInstance;
import com.vaadin.flow.internal.VaadinContextInitializer;
import com.vaadin.flow.server.HandlerHelper.RequestType;
import com.vaadin.flow.server.startup.ApplicationConfiguration;
import com.vaadin.flow.shared.JsonConstants;

/**
 * The main servlet, which handles all incoming requests to the application.
 *

 * This servlet is typically subclassed in all applications to provide servlet
 * mappings and init parameters. Together with a {@literal web.xml} file, it is
 * also possible to use this class directly.
 *

 * Internally sets up a {@link VaadinService} through
 * {@link #createServletService(DeploymentConfiguration)} and delegates handling
 * of most requests to that.
 *
 * @author Vaadin Ltd
 * @since 1.0
 */
public class VaadinServlet extends HttpServlet {
    private VaadinService vaadinService;
    private StaticFileHandler staticFileHandler;

    private volatile boolean isServletInitialized;

    /**
     * Called by the servlet container to indicate to a servlet that the servlet
     * is being placed into service.
     *
     * @param servletConfig
     *            the object containing the servlet's configuration and
     *            initialization parameters
     * @throws ServletException
     *             if an exception has occurred that interferes with the
     *             servlet's normal operation.
     */
    @Override
    public void init(ServletConfig servletConfig) throws ServletException {
        CurrentInstance.clearAll();

        try {
            /*
             * There are plenty of reasons why the check should be done. The
             * main reason is: init method is public which means that everyone
             * may call this method at any time (including an app developer).
             * But it's not supposed to be called any times any time.
             *
             * This code protects weak API from being called several times so
             * that config is reset after the very first initialization.
             *
             * Normally "init" method is called only once by the servlet
             * container. But in a specific OSGi case {@code
             * ServletContextListener} may be called after the servlet
             * initialized. To be able to initialize the VaadinServlet properly
             * its "init" method is called from the {@code
             * ServletContextListener} with the same ServletConfig instance.
             */
            VaadinContext vaadinContext = null;
            if (getServletConfig() == null) {
                isServletInitialized = true;
                super.init(servletConfig);

                vaadinContext = initializeContext();
            }

            if (getServletConfig() != servletConfig) {
                throw new IllegalArgumentException(
                        "Servlet config instance may not differ from the "
                                + "instance which has been used for the initial method call");
            }

            if (vaadinContext == null) {
                vaadinContext = new VaadinServletContext(
                        getServletConfig().getServletContext());
            }

            if (vaadinService != null || vaadinContext
                    .getAttribute(Lookup.class) == null) {
                return;
            }

            try {
                vaadinService = createServletService();
            } catch (ServiceException e) {
                throw new ServletException("Could not initialize VaadinServlet",
                        e);
            }

            // Sets current service as it is needed in static file server even
            // though there are no request and response.
            vaadinService.setCurrentInstances(null, null);

            staticFileHandler = createStaticFileHandler(vaadinService);

            servletInitialized();
        } finally {
            CurrentInstance.clearAll();
        }
    }

    @Override
    public ServletConfig getServletConfig() {
        if (isServletInitialized) {
            return super.getServletConfig();
        }
        return null;
    }

    /**
     * Creates a new instance of {@link StaticFileHandler}, that is responsible
     * to find and serve static resources. By default it returns a
     * {@link StaticFileServer} instance.
     *
     * @param vaadinService
     *            the vaadinService created at {@link #createServletService()}
     * @return the file server to be used by this servlet, not null
     */
    protected StaticFileHandler createStaticFileHandler(
            VaadinService vaadinService) {
        return new StaticFileServer(vaadinService);
    }

    protected void servletInitialized() throws ServletException {
        // Empty by default
    }

    /**
     * Gets the currently used Vaadin servlet. The current servlet is
     * automatically defined when initializing the servlet and when processing
     * requests to the server (see {@link ThreadLocal}) and in
     * {@link VaadinSession#access(Command)} and {@link UI#access(Command)}. In
     * other cases, (e.g. from background threads), the current servlet is not
     * automatically defined.
     *

     * The current servlet is derived from the current service using
     * {@link VaadinService#getCurrent()}
     *
     * @return the current Vaadin servlet instance if available, otherwise
     *         null
     *
     */
    public static VaadinServlet getCurrent() {
        VaadinService vaadinService = CurrentInstance.get(VaadinService.class);
        if (vaadinService instanceof VaadinServletService) {
            VaadinServletService vss = (VaadinServletService) vaadinService;
            return vss.getServlet();
        } else {
            return null;
        }
    }

    /**
     * Creates a deployment configuration to be used for the creation of a
     * {@link VaadinService}. Intended to be used by dependency injection
     * frameworks.
     *
     * @return the created deployment configuration
     */
    protected DeploymentConfiguration createDeploymentConfiguration()
            throws ServletException {
        return createDeploymentConfiguration(
                new DeploymentConfigurationFactory().createInitParameters(
                        getClass(),
                        new VaadinServletConfig(getServletConfig())));
    }

    /**
     * Creates a deployment configuration to be used for the creation of a
     * {@link VaadinService}. Override this if you want to override certain
     * properties.
     *
     * @param initParameters
     *            the context-param and init-param values as properties
     * @return the created deployment configuration
     */
    protected DeploymentConfiguration createDeploymentConfiguration(
            Properties initParameters) {
        VaadinServletContext context = new VaadinServletContext(
                getServletContext());
        return new DefaultDeploymentConfiguration(
                ApplicationConfiguration.get(context), getClass(),
                initParameters);
    }

    /**
     * Creates a vaadin servlet service. This method functions as a layer of
     * indirection between {@link #init(ServletConfig)} and
     * {@link #createServletService(DeploymentConfiguration)} so dependency
     * injection frameworks can call {@link #createDeploymentConfiguration()}
     * when creating a vaadin servlet service lazily.
     *
     * @return the created vaadin servlet service
     *
     * @throws ServletException
     *             if creating a deployment configuration fails
     * @throws ServiceException
     *             if creating the vaadin servlet service fails
     */
    protected VaadinServletService createServletService()
            throws ServletException, ServiceException {
        return createServletService(createDeploymentConfiguration());
    }

    /**
     * Creates a vaadin servlet service.
     *
     * @param deploymentConfiguration
     *            the deployment configuration to be used
     *
     * @return the created vaadin servlet service
     *
     * @throws ServiceException
     *             if creating the vaadin servlet service fails
     */
    protected VaadinServletService createServletService(
            DeploymentConfiguration deploymentConfiguration)
            throws ServiceException {
        VaadinServletService service = new VaadinServletService(this,
                deploymentConfiguration);
        service.init();
        return service;
    }

    /**
     * Receives standard HTTP requests from the public service method and
     * dispatches them.
     *
     * @param request
     *            the object that contains the request the client made of the
     *            servlet.
     * @param response
     *            the object that contains the response the servlet returns to
     *            the client.
     * @throws ServletException
     *             if an input or output error occurs while the servlet is
     *             handling the TRACE request.
     * @throws IOException
     *             if the request for the TRACE cannot be handled.
     */
    @Override
    protected void service(HttpServletRequest request,
            HttpServletResponse response) throws ServletException, IOException {

        // Handle context root request without trailing slash, see
        // https://github.com/vaadin/framework/issues/2991
        if (handleContextOrServletRootWithoutSlash(request, response)) {
            return;
        }

        if (serveStaticOrWebJarRequest(request, response)) {
            return;
        }

        CurrentInstance.clearAll();

        VaadinRequest vaadinRequest = createVaadinRequest(request);
        VaadinResponse vaadinResponse = createVaadinResponse(response);
        if (!ensureCookiesEnabled(vaadinRequest, vaadinResponse)) {
            return;
        }

        try {
            getService().handleRequest(vaadinRequest, vaadinResponse);
        } catch (ServiceException e) {
            throw new ServletException(e);
        }

    }

    /**
     * Handles a request by serving a static file from Webpack when in
     * npm-dev-mode, or from a WebJar when in bower-dev-mode or from the
     * file-system when in production.
     *
     * It's not done via {@link VaadinService} handlers because static requests
     * do not need a established session.
     *
     * @param request
     *            the HTTP servlet request object that contains the request the
     *            client made of the servlet
     *
     * @param response
     *            the HTTP servlet response object that contains the response
     *            the servlet returns to the client
     * @return true if the request was handled a response written;
     *         otherwise false
     *
     * @exception IOException
     *                if an input or output error occurs while the servlet is
     *                handling the HTTP request
     */
    protected boolean serveStaticOrWebJarRequest(HttpServletRequest request,
            HttpServletResponse response) throws IOException {
        DevModeHandler handler = DevModeHandler.getDevModeHandler();

        if (handler != null && handler.isDevModeRequest(request)
                && handler.serveDevModeRequest(request, response)) {
            return true;
        }

        if (staticFileHandler.isStaticResourceRequest(request)) {
            staticFileHandler.serveStaticResource(request, response);
            return true;
        }

        return false;
    }

    /**
     * Invoked for every request to this servlet to potentially send a redirect
     * to avoid problems with requests to the context root with no trailing
     * slash.
     *
     * @param request
     *            the processed request
     * @param response
     *            the processed response
     * @return true if a redirect has been sent and the request
     *         should not be processed further; false if the
     *         request should be processed as usual
     * @throws IOException
     *             If an input or output exception occurs
     */
    protected boolean handleContextOrServletRootWithoutSlash(
            HttpServletRequest request, HttpServletResponse response)
            throws IOException {
        // Query parameters like "?a=b" are handled by the servlet container but
        // path parameter (e.g. ;jsessionid=) needs to be handled here
        String location = request.getRequestURI();

        String lastPathParameter = getLastPathParameter(location);
        location = location.substring(0,
                location.length() - lastPathParameter.length());

        if ((request.getPathInfo() == null || "/".equals(request.getPathInfo()))
                && !location.endsWith("/")) {
            /*
             * Path info is for the root but request URI doesn't end with a
             * slash -> redirect to the same URI but with an ending slash.
             */
            location = location + "/" + lastPathParameter;
            String queryString = request.getQueryString();
            if (queryString != null) {
                // Prevent HTTP Response splitting in case the server doesn't
                queryString = queryString.replaceAll("[\\r\\n]", "");
                location += '?' + queryString;
            }
            response.sendRedirect(location);
            return true;
        } else {
            return false;
        }
    }

    /**
     * Finds any path parameter added to the last part of the uri. A path
     * parameter is any string separated by ";" from the path and ends in / or
     * at the end of the string.
     *

     * For example the uri http://myhost.com/foo;a=1/bar;b=1 contains two path
     * parameters, {@literal a=1} related to {@literal /foo} and {@literal b=1}
     * related to /bar.
     *

     * For http://myhost.com/foo;a=1/bar;b=1 this method will return ;b=1
     *
     * @param uri
     *            a URI
     * @return the last path parameter of the uri including the semicolon or an
     *         empty string. Never null.
     */
    protected static String getLastPathParameter(String uri) {
        int lastPathStart = uri.lastIndexOf('/');
        if (lastPathStart == -1) {
            return "";
        }

        int semicolonPos = uri.indexOf(';', lastPathStart);
        if (semicolonPos < 0) {
            // No path parameter for the last part
            return "";
        } else {
            // This includes the semicolon.
            String semicolonString = uri.substring(semicolonPos);
            return semicolonString;
        }
    }

    private VaadinResponse createVaadinResponse(
            HttpServletResponse response) {
        return new VaadinServletResponse(response, getService());
    }

    /**
     * Creates a Vaadin request for a http servlet request. This method can be
     * overridden if the Vaadin request should have special properties.
     *
     * @param request
     *            the original http servlet request
     * @return a Vaadin request for the original request
     */
    protected VaadinServletRequest createVaadinRequest(
            HttpServletRequest request) {
        return new VaadinServletRequest(request, getService());
    }

    /**
     * Gets the Vaadin service for this servlet.
     *
     * @return the Vaadin service
     */
    public VaadinService getService() {
        return vaadinService;
    }

    /**
     * Check that cookie support is enabled in the browser. Only checks UIDL
     * requests.
     *
     * @param request
     *            The request from the browser
     * @param response
     *            The response to which an error can be written
     * @return false if cookies are disabled, true otherwise
     * @throws IOException
     */
    private boolean ensureCookiesEnabled(VaadinRequest request,
            VaadinResponse response) throws IOException {
        if (HandlerHelper.isRequestType(request, RequestType.UIDL)) {
            // In all other but the first UIDL request a cookie should be
            // returned by the browser.
            // This can be removed if cookieless mode (#3228) is supported
            if (request instanceof HttpServletRequest && ((HttpServletRequest) request).getRequestedSessionId() == null) {
                // User has cookies disabled
                SystemMessages systemMessages = getService().getSystemMessages(
                        HandlerHelper.findLocale(null, request), request);
                getService().writeUncachedStringResponse(response,
                        JsonConstants.JSON_CONTENT_TYPE,
                        VaadinService.createCriticalNotificationJSON(
                                systemMessages.getCookiesDisabledCaption(),
                                systemMessages.getCookiesDisabledMessage(),
                                null, systemMessages.getCookiesDisabledURL()));
                return false;
            }
        }
        return true;
    }

    /**
     * Gets the current application URL from request.
     *
     * @param request
     *            the HTTP request.
     * @throws MalformedURLException
     *             if the application is denied access to the persistent data
     *             store represented by the given URL.
     *
     * @return current application URL
     */
    static URL getApplicationUrl(HttpServletRequest request)
            throws MalformedURLException {
        final URL reqURL = new URL((request.isSecure() ? "https://" : "http://")
                + request.getServerName()
                + ((request.isSecure() && request.getServerPort() == 443)
                        || (!request.isSecure()
                                && request.getServerPort() == 80) ? ""
                                        : ":" + request.getServerPort())
                + request.getRequestURI());
        String servletPath;
        if (request
                .getAttribute("javax.servlet.include.servlet_path") != null) {
            // this is an include request
            servletPath = request
                    .getAttribute("javax.servlet.include.context_path")
                    .toString()
                    + request
                            .getAttribute("javax.servlet.include.servlet_path");

        } else {
            servletPath = request.getContextPath() + request.getServletPath();
        }

        if (servletPath.length() == 0
                || servletPath.charAt(servletPath.length() - 1) != '/') {
            servletPath = servletPath + "/";
        }
        URL u = new URL(reqURL, servletPath);
        return u;
    }

    /*
     * (non-Javadoc)
     *
     * @see javax.servlet.GenericServlet#destroy()
     */
    @Override
    public void destroy() {
        super.destroy();
        isServletInitialized = false;
        if (getService() != null) {
            getService().destroy();
        }
    }

    private VaadinContext initializeContext() {
        ServletContext servletContext = getServletConfig().getServletContext();
        VaadinServletContext vaadinServletContext = new VaadinServletContext(
                servletContext);
        // ensure the web application classloader is available via context
        ApplicationClassLoaderAccess access = () -> servletContext
                .getClassLoader();
        vaadinServletContext.getAttribute(ApplicationClassLoaderAccess.class,
                () -> access);

        VaadinContextInitializer initializer = vaadinServletContext
                .getAttribute(VaadinContextInitializer.class);
        if (initializer != null) {
            initializer.initialize(vaadinServletContext);
        }
        return vaadinServletContext;
    }

}

## 内容4
### 文件路径：
flow-server/src/main/java/com/vaadin/flow/server/startup/LookupServletContainerInitializer.java
### 代码内容：
package com.vaadin.flow.server.startup;

import javax.servlet.ServletContainerInitializer;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.annotation.HandlesTypes;

import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;
import java.util.stream.Collectors;
import java.util.stream.Stream;

import com.vaadin.flow.component.template.internal.DeprecatedPolymerPublishedEventHandler;
import com.vaadin.flow.di.AbstractLookupInitializer;
import com.vaadin.flow.di.InstantiatorFactory;
import com.vaadin.flow.di.Lookup;
import com.vaadin.flow.di.LookupInitializer;
import com.vaadin.flow.di.ResourceProvider;
import com.vaadin.flow.function.VaadinApplicationInitializationBootstrap;
import com.vaadin.flow.internal.ReflectTools;
import com.vaadin.flow.server.VaadinContext;
import com.vaadin.flow.server.VaadinServletContext;
import com.vaadin.flow.server.frontend.EndpointGeneratorTaskFactory;

/**
 * Standard servlet initializer for collecting all SPI implementations.
 *
 * @author Vaadin Ltd
 * @since
 *
 */
@HandlesTypes({ ResourceProvider.class, InstantiatorFactory.class,
        DeprecatedPolymerPublishedEventHandler.class,
        EndpointGeneratorTaskFactory.class,
        ApplicationConfigurationFactory.class, AbstractLookupInitializer.class,
        AppShellPredicate.class })
public class LookupServletContainerInitializer
        implements ClassLoaderAwareServletContainerInitializer {

    @Override
    public void process(Set<Class<?>> classSet, ServletContext servletContext)
            throws ServletException {
        if (!classSet.contains(LookupInitializer.class)) {
            // this is a specific case for OSGi (PAX web): at some point it may
            // decide to apply ServletContainerInitializers for non WAR case
            // even though it has no any sense to do it because the {@code
            // classSet} is always empty. In normal environment if Servlet
            // container properly supports ServletContainerInitializers then
            // {@code classSet} has to contain at least LookupInitializer.
            // Otherwise LookupServletContainerInitializer should not be
            // executed at all.
            return;
        }
        VaadinServletContext vaadinContext = new VaadinServletContext(
                servletContext);
        Map<Class<?>, Collection<Class<?>>> services = new HashMap<>();

        collectSubclasses(AbstractLookupInitializer.class, classSet, services);

        AbstractLookupInitializer initializer = getLookupInitializer(services);

        services.remove(AbstractLookupInitializer.class);

        collectServiceImplementations(classSet, services);

        initializer.initialize(vaadinContext, services, lookup -> {
            vaadinContext.setAttribute(Lookup.class, lookup);

            DeferredServletContextInitializers deferredInitializers;
            synchronized (servletContext) {
                deferredInitializers = vaadinContext
                        .getAttribute(DeferredServletContextInitializers.class);
                vaadinContext.removeAttribute(
                        DeferredServletContextInitializers.class);
            }

            if (deferredInitializers != null) {
                deferredInitializers.runInitializers(servletContext);
            }
        });
    }

    @Override
    public boolean requiresLookup() {
        return false;
    }

    /**
     * Gets the service types that are used to set services into the
     * {@link Lookup} based on found subtypes by the
     * {@link ServletContainerInitializer}.
     *

     * {@link LookupServletContainerInitializer} uses
     * {@link ServletContainerInitializer} classes discovering mechanism based
     * on {@link HandlesTypes} annotation. The method may be overridden to
     * return the service types which should be put into the {@link Lookup}
     * instance if another mechanism of class searching is used (e.g. Spring
     * boot case).
     *

     * The set of classes (passed into the {@link #process(Set, ServletContext)}
     * method) will be filtered via checking whether they are assignable to the
     * service types and the resulting classes will be instantiated via
     * reflection.
     *
     * @return a collection of service types which should be available via
     *         Lookup
     * @see LookupInitializer#initialize(VaadinContext, Map,
     *      VaadinApplicationInitializationBootstrap)
     */
    protected Collection<Class<?>> getServiceTypes() {
        HandlesTypes annotation = getClass().getAnnotation(HandlesTypes.class);
        if (annotation == null) {
            throw new IllegalStateException(
                    "Cannot collect service types based on "
                            + HandlesTypes.class.getSimpleName()
                            + " annotation. The default 'getServiceTypes' method implementation can't be used.");
        }
        return Stream.of(annotation.value())
                .filter(clazz -> !clazz.equals(LookupInitializer.class))
                .collect(Collectors.toSet());
    }

    private void collectServiceImplementations(Set<Class<?>> classSet,
            Map<Class<?>, Collection<Class<?>>> services) {
        for (Class<?> serviceType : getServiceTypes()) {
            collectSubclasses(serviceType, classSet, services);
        }

    }

    private void collectSubclasses(Class<?> clazz, Set<Class<?>> classSet,
            Map<Class<?>, Collection<Class<?>>> services) {
        services.put(clazz, filterSubClasses(clazz, classSet).stream()
                .collect(Collectors.toList()));
    }

    private Set<Class<?>> filterSubClasses(Class<?> clazz,
            Set<Class<?>> classes) {
        return classes == null ? Collections.emptySet()
                : classes.stream().filter(clazz::isAssignableFrom)
                        .filter(ReflectTools::isInstantiableService)
                        .filter(cls -> !clazz.equals(cls))
                        .collect(Collectors.toSet());
    }

    private AbstractLookupInitializer getLookupInitializer(
            Map<Class<?>, Collection<Class<?>>> services)
            throws ServletException {
        Collection<Class<?>> initializers = services
                .remove(AbstractLookupInitializer.class);
        if (initializers == null) {
            initializers = Collections.emptyList();
        } else {
            initializers.remove(LookupInitializer.class);
        }

        AbstractLookupInitializer initializer;
        if (initializers.isEmpty()) {
            initializer = new LookupInitializer();
        } else if (initializers.size() > 1) {
            throw new ServletException("Several implementation of "
                    + AbstractLookupInitializer.class.getSimpleName()
                    + " are found in the claspath: " + initializers);
        } else {
            initializer = AbstractLookupInitializer.class.cast(ReflectTools
                    .createInstance(initializers.iterator().next()));
        }
        return initializer;
    }
}

Output:
【漏洞类型】路径遍历漏洞
【严重性】高
【漏洞摘要】路径遍历漏洞允许攻击者通过操纵输入路径来访问服务器上的文件，绕过安全限制。在修复代码中，`StaticFileServer` 类的 `isStaticResourceRequest` 方法和 `serveStaticResource` 方法中使用了用户输入的 `requestFilename` 作为资源路径，但没有进行充分的验证和过滤，可能导致路径遍历攻击。具体表现为：
- 在 `isStaticResourceRequest` 方法中，`requestFilename` 直接用于查找资源，没有进行路径规范化或过滤。
- 在 `serveStaticResource` 方法中，`requestFilename` 也被直接用于查找资源，同样没有进行路径规范化或过滤。
【关键代码模式】
- `isStaticResourceRequest` 方法中的 `vaadinService.getStaticResource(requestFilename)`
- `serveStaticResource` 方法中的 `vaadinService.getStaticResource(filenameWithPath)`
- `getRequestFilename` 方法中的路径拼接和提取
【修复方法说明】通过引入 `StaticFileHandlerFactory` 接口和 `StaticFileHandlerFactoryImpl` 实现类，将静态文件处理逻辑抽象为服务，并在 `VaadinServlet` 中通过 `Lookup` 获取 `StaticFileHandler` 实例，从而避免了直接使用用户输入的路径。


Instruction:
作为 Java 安全专家，检测此代码中的安全漏洞：
## 内容1
### 文件路径：
server/src/main/java/com/vaadin/data/validator/EmailValidator.java
### 代码内容：
package com.vaadin.data.validator;

/**
 * String validator for e-mail addresses. The e-mail address syntax is not
 * complete according to RFC 822 but handles the vast majority of valid e-mail
 * addresses correctly.
 *
 * See {@link AbstractStringValidator} for more information.
 *
 * <p>
 * An empty string or a null is always accepted - use the required flag on
 * fields or a separate validator (or override {@link #isValidValue(String)}) to
 * fail on empty values.
 * </p>
 *
 * @author Vaadin Ltd.
 * @since 5.4
 */
@SuppressWarnings("serial")
public class EmailValidator extends RegexpValidator {

    /**
     * Creates a validator for checking that a string is a syntactically valid
     * e-mail address.
     *
     * @param errorMessage
     *            the message to display in case the value does not validate.
     */
    public EmailValidator(String errorMessage) {
        super("^([a-zA-Z0-9_\\.\\-+])+@(([a-zA-Z0-9-])+\\.)+([a-zA-Z0-9]{2,4})+$",
                true, errorMessage);
    }
}

Output:
【漏洞类型】正则表达式漏洞
【严重性】Medium
【漏洞摘要】原始代码中用于验证电子邮件地址的正则表达式存在一些安全问题，虽然它能够处理大部分有效的电子邮件地址，但仍然存在一些不符合RFC 822标准的电子邮件地址可以通过验证。具体来说，原始正则表达式对域名和顶级域名（TLD）的长度进行了限制（TLD最多4个字符），这可能会导致一些合法的电子邮件地址无法通过验证。此外，未使用任何安全编码实践来处理正则表达式的潜在问题。
【关键代码模式】RegexpValidator、super()、正则表达式、电子邮件验证
【修复方法说明】修复方法通过更新正则表达式模式来放宽对域名和TLD长度的限制，同时保持对合法电子邮件地址的验证。这解决了原始正则表达式的限制问题。最佳实践是使用经过验证和测试的正则表达式模式来确保对所有合法电子邮件地址的正确验证。