Aias00 commented on code in PR #7874: URL: https://github.com/apache/shenyu/pull/7874#discussion_r4322640440
########## shenyu-common/src/main/java/org/apache/shenyu/common/utils/RewriteHandleUtils.java: ########## @@ -0,0 +1,70 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one or more + * contributor license agreements. See the NOTICE file distributed with + * this work for additional information regarding copyright ownership. + * The ASF licenses this file to You under the Apache License, Version 2.0 + * (the "License"); you may not use this file except in compliance with + * the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +package org.apache.shenyu.common.utils; + +import org.apache.commons.lang3.StringUtils; + +import java.util.regex.Pattern; +import java.util.regex.PatternSyntaxException; + +/** + * The utils that tell whether a rewrite expression can be applied by the rewrite plugin. + */ +public final class RewriteHandleUtils { + + private static final String INVALID_REGEX = "invalid regular expression: "; + + private static final String INVALID_REPLACEMENT = "invalid replacement template: "; + + private RewriteHandleUtils() { + } + + /** + * Explain why a rewrite expression cannot be applied. + * + * <p>The plugin expands the replacement with {@link String#replaceAll(String, String)}, so the + * replacement is a template in which a dollar sign references a regex group. The pair is therefore + * dry-run against the empty input to let the JDK parser validate both parts. An incomplete + * expression and the placeholder mode, where both values contain a left brace, are always + * applicable because the plugin skips them or substitutes them literally.</p> + * + * @param regex the configured regular expression + * @param replace the configured replacement template + * @return {@code null} when the plugin can apply the expression, otherwise the reason why it cannot + */ + public static String unapplicableReason(final String regex, final String replace) { + if (StringUtils.isAnyBlank(regex, replace)) { + return null; + } + if (replace.contains("{") && regex.contains("{")) { + return null; + } + try { + // the trailing empty alternative makes the empty input match, so the replacement is parsed too + // the configured value is only dry-run against an empty input and never rewrites a request + // CHECKSTYLE:OFF + Pattern.compile(regex + "|").matcher("").replaceAll(replace); // lgtm[java/regex-injection] Review Comment: @klT45 this must be handled -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
