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feat: support single character wildcard resource matching
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177 changes: 177 additions & 0 deletions
177
src/main/java/com/aws/greengrass/clientdevices/auth/util/WildcardTrie.java
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,177 @@ | ||
| /* | ||
| * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved. | ||
| * SPDX-License-Identifier: Apache-2.0 | ||
| */ | ||
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| package com.aws.greengrass.clientdevices.auth.util; | ||
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| import edu.umd.cs.findbugs.annotations.SuppressFBWarnings; | ||
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| import java.util.HashMap; | ||
| import java.util.Map; | ||
| import java.util.function.Supplier; | ||
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| public class WildcardTrie { | ||
| private static final String GLOB_WILDCARD = "*"; | ||
| private static final String SINGLE_CHAR_WILDCARD = "?"; | ||
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| private final Map<String, WildcardTrie> children = new DefaultHashMap<>(WildcardTrie::new); | ||
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| private boolean isTerminal; | ||
| private boolean isGlobWildcard; | ||
| private boolean isSingleCharWildcard; | ||
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| public void add(String subject) { | ||
| add(subject, true); | ||
| } | ||
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| private WildcardTrie add(String subject, boolean isTerminal) { | ||
| if (subject == null || subject.isEmpty()) { | ||
| this.isTerminal |= isTerminal; | ||
| return this; | ||
| } | ||
| StringBuilder currPrefix = new StringBuilder(subject.length()); | ||
| for (int i = 0; i < subject.length(); i++) { | ||
| char c = subject.charAt(i); | ||
| if (c == GLOB_WILDCARD.charAt(0)) { | ||
| return addGlobWildcard(subject, currPrefix.toString(), isTerminal); | ||
| } | ||
| if (c == SINGLE_CHAR_WILDCARD.charAt(0)) { | ||
| return addSingleCharWildcard(subject, currPrefix.toString(), isTerminal); | ||
| } | ||
| currPrefix.append(c); | ||
| } | ||
| WildcardTrie node = children.get(currPrefix.toString()); | ||
| node.isTerminal |= isTerminal; | ||
| return node; | ||
| } | ||
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| private WildcardTrie addGlobWildcard(String subject, String currPrefix, boolean isTerminal) { | ||
| WildcardTrie node = this; | ||
| node = node.add(currPrefix, false); | ||
| node = node.children.get(GLOB_WILDCARD); | ||
| node.isGlobWildcard = true; | ||
| // wildcard at end of subject is terminal | ||
| if (subject.length() - currPrefix.length() == 1) { | ||
| node.isTerminal = isTerminal; | ||
| return node; | ||
| } | ||
| return node.add(subject.substring(currPrefix.length() + 2), true); | ||
| } | ||
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| private WildcardTrie addSingleCharWildcard(String subject, String currPrefix, boolean isTerminal) { | ||
| WildcardTrie node = this; | ||
| node = node.add(currPrefix, false); | ||
| node = node.children.get(SINGLE_CHAR_WILDCARD); | ||
| node.isSingleCharWildcard = true; | ||
| // wildcard at end of subject is terminal | ||
| if (subject.length() - currPrefix.length() == 1) { | ||
| node.isTerminal = isTerminal; | ||
| return node; | ||
| } | ||
| return node.add(subject.substring(currPrefix.length() + 1), true); | ||
| } | ||
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| public boolean matches(String s) { | ||
| return matches(s, true); | ||
| } | ||
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| public boolean matches(String s, boolean matchSingleCharWildcard) { | ||
| if (s == null) { | ||
| return children.isEmpty(); | ||
| } | ||
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| if ((isWildcard() && isTerminal) || (isTerminal && s.isEmpty())) { | ||
| return true; | ||
| } | ||
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| boolean childMatchesWildcard = children | ||
| .values() | ||
| .stream() | ||
| .filter(WildcardTrie::isWildcard) | ||
| .filter(childNode -> matchSingleCharWildcard || !childNode.isSingleCharWildcard) | ||
| .anyMatch(childNode -> childNode.matches(s, matchSingleCharWildcard)); | ||
| if (childMatchesWildcard) { | ||
| return true; | ||
| } | ||
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| if (matchSingleCharWildcard) { | ||
| boolean childMatchesSingleCharWildcard = children | ||
| .values() | ||
| .stream() | ||
| .filter(childNode -> childNode.isSingleCharWildcard) | ||
| .anyMatch(childNode -> childNode.matches(s, matchSingleCharWildcard)); | ||
| if (childMatchesSingleCharWildcard) { | ||
| return true; | ||
| } | ||
| } | ||
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| boolean childMatchesRegularCharacters = children | ||
| .keySet() | ||
| .stream() | ||
| .filter(s::startsWith) | ||
| .anyMatch(childToken -> { | ||
| WildcardTrie childNode = children.get(childToken); | ||
| String rest = s.substring(childToken.length()); | ||
| return childNode.matches(rest, matchSingleCharWildcard); | ||
| }); | ||
| if (childMatchesRegularCharacters) { | ||
| return true; | ||
| } | ||
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| if (isWildcard() && !isTerminal) { | ||
| return findMatchingChildSuffixesAfterWildcard(s, matchSingleCharWildcard) | ||
| .entrySet() | ||
| .stream() | ||
| .anyMatch((e) -> { | ||
| String suffix = e.getKey(); | ||
| WildcardTrie childNode = e.getValue(); | ||
| return childNode.matches(suffix, matchSingleCharWildcard); | ||
| }); | ||
| } | ||
| return false; | ||
| } | ||
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| private Map<String, WildcardTrie> findMatchingChildSuffixesAfterWildcard(String s, boolean matchSingleCharWildcard) { | ||
| Map<String, WildcardTrie> matchingSuffixes = new HashMap<>(); | ||
| for (Map.Entry<String, WildcardTrie> e : children.entrySet()) { | ||
| String childToken = e.getKey(); | ||
| WildcardTrie childNode = e.getValue(); | ||
| int suffixIndex = s.indexOf(childToken); | ||
| if (matchSingleCharWildcard && suffixIndex > 1) { | ||
| continue; | ||
| } | ||
| while (suffixIndex >= 0) { | ||
| matchingSuffixes.put(s.substring(suffixIndex + childToken.length()), childNode); | ||
| suffixIndex = s.indexOf(childToken, suffixIndex + 1); | ||
| } | ||
| } | ||
| return matchingSuffixes; | ||
| } | ||
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| private boolean isWildcard() { | ||
| return isGlobWildcard || isSingleCharWildcard; | ||
| } | ||
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| @SuppressFBWarnings("EQ_DOESNT_OVERRIDE_EQUALS") | ||
| private static class DefaultHashMap<K, V> extends HashMap<K, V> { | ||
|
Check failure Code scanning / CodeQL No clone method Error
No clone method, yet implements Cloneable.
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| private final transient Supplier<V> defaultVal; | ||
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| public DefaultHashMap(Supplier<V> defaultVal) { | ||
| super(); | ||
| this.defaultVal = defaultVal; | ||
| } | ||
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| @Override | ||
| @SuppressWarnings("unchecked") | ||
| public V get(Object key) { | ||
| return super.computeIfAbsent((K) key, (k) -> defaultVal.get()); | ||
| } | ||
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| @Override | ||
| public boolean containsKey(Object key) { | ||
| return super.get(key) != null; | ||
| } | ||
| } | ||
| } | ||
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