Extract shared resource handling utility methods

Closes: gh-33574

Author: rstoyanchev

spring-webflux/src/main/java/org/springframework/web/reactive/function/server/PathResourceLookupFunction.java

@@ -18,20 +18,14 @@
 
 import java.io.IOException;
 import java.io.UncheckedIOException;
-import java.net.URLDecoder;
-import java.nio.charset.StandardCharsets;
 import java.util.function.Function;
 
 import reactor.core.publisher.Mono;
 
-import org.springframework.core.io.ClassPathResource;
 import org.springframework.core.io.Resource;
-import org.springframework.core.io.UrlResource;
 import org.springframework.http.server.PathContainer;
 import org.springframework.util.Assert;
-import org.springframework.util.ResourceUtils;
-import org.springframework.util.StringUtils;
-import org.springframework.web.util.UriUtils;
+import org.springframework.web.reactive.resource.ResourceHandlerUtils;
 import org.springframework.web.util.pattern.PathPattern;
 import org.springframework.web.util.pattern.PathPatternParser;
 
@@ -64,21 +58,14 @@ public Mono<Resource> apply(ServerRequest request) {
 		}
 
 		pathContainer = this.pattern.extractPathWithinPattern(pathContainer);
-		String path = processPath(pathContainer.value());
-		if (!StringUtils.hasText(path) || isInvalidPath(path)) {
+		String path = ResourceHandlerUtils.normalizeInputPath(pathContainer.value());
+		if (ResourceHandlerUtils.shouldIgnoreInputPath(path)) {
 			return Mono.empty();
 		}
-		if (isInvalidEncodedInputPath(path)) {
-			return Mono.empty();
-		}
-
-		if (!(this.location instanceof UrlResource)) {
-			path = UriUtils.decode(path, StandardCharsets.UTF_8);
-		}
 
 		try {
-			Resource resource = this.location.createRelative(path);
-			if (resource.isReadable() && isResourceUnderLocation(resource)) {
+			Resource resource = ResourceHandlerUtils.createRelativeResource(this.location, path);
+			if (resource.isReadable() && ResourceHandlerUtils.isResourceUnderLocation(this.location, resource)) {
 				return Mono.just(resource);
 			}
 			else {
@@ -90,147 +77,6 @@ public Mono<Resource> apply(ServerRequest request) {
 		}
 	}
 
-	/**
-	 * Process the given resource path.
-	 * <p>The default implementation replaces:
-	 * <ul>
-	 * <li>Backslash with forward slash.
-	 * <li>Duplicate occurrences of slash with a single slash.
-	 * <li>Any combination of leading slash and control characters (00-1F and 7F)
-	 * with a single "/" or "". For example {@code "  / // foo/bar"}
-	 * becomes {@code "/foo/bar"}.
-	 * </ul>
-	 */
-	protected String processPath(String path) {
-		path = StringUtils.replace(path, "\\", "/");
-		path = cleanDuplicateSlashes(path);
-		return cleanLeadingSlash(path);
-	}
-
-	private String cleanDuplicateSlashes(String path) {
-		StringBuilder sb = null;
-		char prev = 0;
-		for (int i = 0; i < path.length(); i++) {
-			char curr = path.charAt(i);
-			try {
-				if (curr == '/' && prev == '/') {
-					if (sb == null) {
-						sb = new StringBuilder(path.substring(0, i));
-					}
-					continue;
-				}
-				if (sb != null) {
-					sb.append(path.charAt(i));
-				}
-			}
-			finally {
-				prev = curr;
-			}
-		}
-		return (sb != null ? sb.toString() : path);
-	}
-
-	private String cleanLeadingSlash(String path) {
-		boolean slash = false;
-		for (int i = 0; i < path.length(); i++) {
-			if (path.charAt(i) == '/') {
-				slash = true;
-			}
-			else if (path.charAt(i) > ' ' && path.charAt(i) != 127) {
-				if (i == 0 || (i == 1 && slash)) {
-					return path;
-				}
-				return (slash ? "/" + path.substring(i) : path.substring(i));
-			}
-		}
-		return (slash ? "/" : "");
-	}
-
-	private boolean isInvalidPath(String path) {
-		if (path.contains("WEB-INF") || path.contains("META-INF")) {
-			return true;
-		}
-		if (path.contains(":/")) {
-			String relativePath = (path.charAt(0) == '/' ? path.substring(1) : path);
-			if (ResourceUtils.isUrl(relativePath) || relativePath.startsWith("url:")) {
-				return true;
-			}
-		}
-		if (path.contains("..") && StringUtils.cleanPath(path).contains("../")) {
-			return true;
-		}
-		return false;
-	}
-
-	/**
-	 * Check whether the given path contains invalid escape sequences.
-	 * @param path the path to validate
-	 * @return {@code true} if the path is invalid, {@code false} otherwise
-	 */
-	private boolean isInvalidEncodedInputPath(String path) {
-		if (path.contains("%")) {
-			try {
-				// Use URLDecoder (vs UriUtils) to preserve potentially decoded UTF-8 chars
-				String decodedPath = URLDecoder.decode(path, StandardCharsets.UTF_8);
-				if (isInvalidPath(decodedPath)) {
-					return true;
-				}
-				decodedPath = processPath(decodedPath);
-				if (isInvalidPath(decodedPath)) {
-					return true;
-				}
-			}
-			catch (IllegalArgumentException ex) {
-				// May not be possible to decode...
-			}
-		}
-		return false;
-	}
-
-	private boolean isResourceUnderLocation(Resource resource) throws IOException {
-		if (resource.getClass() != this.location.getClass()) {
-			return false;
-		}
-
-		String resourcePath;
-		String locationPath;
-
-		if (resource instanceof UrlResource) {
-			resourcePath = resource.getURL().toExternalForm();
-			locationPath = StringUtils.cleanPath(this.location.getURL().toString());
-		}
-		else if (resource instanceof ClassPathResource classPathResource) {
-			resourcePath = classPathResource.getPath();
-			locationPath = StringUtils.cleanPath(((ClassPathResource) this.location).getPath());
-		}
-		else {
-			resourcePath = resource.getURL().getPath();
-			locationPath = StringUtils.cleanPath(this.location.getURL().getPath());
-		}
-
-		if (locationPath.equals(resourcePath)) {
-			return true;
-		}
-		locationPath = (locationPath.endsWith("/") || locationPath.isEmpty() ? locationPath : locationPath + "/");
-		return (resourcePath.startsWith(locationPath) && !isInvalidEncodedResourcePath(resourcePath));
-	}
-
-	private boolean isInvalidEncodedResourcePath(String resourcePath) {
-		if (resourcePath.contains("%")) {
-			// Use URLDecoder (vs UriUtils) to preserve potentially decoded UTF-8 chars...
-			try {
-				String decodedPath = URLDecoder.decode(resourcePath, StandardCharsets.UTF_8);
-				if (decodedPath.contains("../") || decodedPath.contains("..\\")) {
-					return true;
-				}
-			}
-			catch (IllegalArgumentException ex) {
-				// May not be possible to decode...
-			}
-		}
-		return false;
-	}
-
 	@Override
 	public String toString() {
 		return this.pattern + " -> " + this.location;

spring-webflux/src/main/java/org/springframework/web/reactive/resource/PathResourceResolver.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,22 +17,17 @@
 package org.springframework.web.reactive.resource;
 
 import java.io.IOException;
-import java.net.URLDecoder;
-import java.nio.charset.StandardCharsets;
 import java.util.Arrays;
 import java.util.List;
 
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
 
-import org.springframework.core.io.ClassPathResource;
 import org.springframework.core.io.Resource;
-import org.springframework.core.io.UrlResource;
 import org.springframework.core.log.LogFormatUtils;
 import org.springframework.lang.Nullable;
 import org.springframework.util.StringUtils;
 import org.springframework.web.server.ServerWebExchange;
-import org.springframework.web.util.UriUtils;
 
 /**
  * A simple {@code ResourceResolver} that tries to find a resource under the given
@@ -111,10 +106,7 @@ private Mono<Resource> getResource(String resourcePath, List<? extends Resource>
 	 */
 	protected Mono<Resource> getResource(String resourcePath, Resource location) {
 		try {
-			if (!(location instanceof UrlResource)) {
-				resourcePath = UriUtils.decode(resourcePath, StandardCharsets.UTF_8);
-			}
-			Resource resource = location.createRelative(resourcePath);
+			Resource resource = ResourceHandlerUtils.createRelativeResource(location, resourcePath);
 			if (resource.isReadable()) {
 				if (checkResource(resource, location)) {
 					return Mono.just(resource);
@@ -154,61 +146,15 @@ else if (logger.isWarnEnabled()) {
 	 * @return "true" if resource is in a valid location, "false" otherwise
 	 */
 	protected boolean checkResource(Resource resource, Resource location) throws IOException {
-		if (isResourceUnderLocation(resource, location)) {
+		if (ResourceHandlerUtils.isResourceUnderLocation(location, resource)) {
 			return true;
 		}
 		if (getAllowedLocations() != null) {
 			for (Resource current : getAllowedLocations()) {
-				if (isResourceUnderLocation(resource, current)) {
-					return true;
-				}
-			}
-		}
-		return false;
-	}
-
-	private boolean isResourceUnderLocation(Resource resource, Resource location) throws IOException {
-		if (resource.getClass() != location.getClass()) {
-			return false;
-		}
-
-		String resourcePath;
-		String locationPath;
-
-		if (resource instanceof UrlResource) {
-			resourcePath = resource.getURL().toExternalForm();
-			locationPath = StringUtils.cleanPath(location.getURL().toString());
-		}
-		else if (resource instanceof ClassPathResource classPathResource) {
-			resourcePath = classPathResource.getPath();
-			locationPath = StringUtils.cleanPath(((ClassPathResource) location).getPath());
-		}
-		else {
-			resourcePath = resource.getURL().getPath();
-			locationPath = StringUtils.cleanPath(location.getURL().getPath());
-		}
-
-		if (locationPath.equals(resourcePath)) {
-			return true;
-		}
-		locationPath = (locationPath.endsWith("/") || locationPath.isEmpty() ? locationPath : locationPath + "/");
-		return (resourcePath.startsWith(locationPath) && !isInvalidEncodedPath(resourcePath));
-	}
-
-	private boolean isInvalidEncodedPath(String resourcePath) {
-		if (resourcePath.contains("%")) {
-			// Use URLDecoder (vs UriUtils) to preserve potentially decoded UTF-8 chars...
-			try {
-				String decodedPath = URLDecoder.decode(resourcePath, StandardCharsets.UTF_8);
-				if (decodedPath.contains("../") || decodedPath.contains("..\\")) {
-					logger.warn(LogFormatUtils.formatValue(
-							"Resolved resource path contains encoded \"../\" or \"..\\\": " + resourcePath, -1, true));
+				if (ResourceHandlerUtils.isResourceUnderLocation(current, resource)) {
 					return true;
 				}
 			}
-			catch (IllegalArgumentException ex) {
-				// May not be possible to decode...
-			}
 		}
 		return false;
 	}