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Grok.java
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Grok.java
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/*
* Licensed to Elasticsearch under one or more contributor
* license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright
* ownership. Elasticsearch 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.elasticsearch.grok;
import org.jcodings.specific.UTF8Encoding;
import org.joni.Matcher;
import org.joni.NameEntry;
import org.joni.Option;
import org.joni.Regex;
import org.joni.Region;
import org.joni.Syntax;
import org.joni.exception.ValueException;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.UncheckedIOException;
import java.nio.charset.StandardCharsets;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Locale;
import java.util.Map;
import java.util.Collections;
public final class Grok {
private static final String NAME_GROUP = "name";
private static final String SUBNAME_GROUP = "subname";
private static final String PATTERN_GROUP = "pattern";
private static final String DEFINITION_GROUP = "definition";
private static final String GROK_PATTERN =
"%\\{" +
"(?<name>" +
"(?<pattern>[A-z0-9]+)" +
"(?::(?<subname>[[:alnum:]@\\[\\]_:.-]+))?" +
")" +
"(?:=(?<definition>" +
"(?:" +
"(?:[^{}]+|\\.+)+" +
")+" +
")" +
")?" + "\\}";
private static final Regex GROK_PATTERN_REGEX = new Regex(GROK_PATTERN.getBytes(StandardCharsets.UTF_8), 0,
GROK_PATTERN.getBytes(StandardCharsets.UTF_8).length, Option.NONE, UTF8Encoding.INSTANCE, Syntax.DEFAULT);
private static final Map<String, String> builtinPatterns;
static {
try {
builtinPatterns = loadBuiltinPatterns();
} catch (IOException e) {
throw new UncheckedIOException("unable to load built-in grok patterns", e);
}
}
private final Map<String, String> patternBank;
private final boolean namedCaptures;
private final Regex compiledExpression;
private final ThreadWatchdog threadWatchdog;
public Grok(Map<String, String> patternBank, String grokPattern) {
this(patternBank, grokPattern, true, ThreadWatchdog.noop());
}
public Grok(Map<String, String> patternBank, String grokPattern, ThreadWatchdog threadWatchdog) {
this(patternBank, grokPattern, true, threadWatchdog);
}
Grok(Map<String, String> patternBank, String grokPattern, boolean namedCaptures) {
this(patternBank, grokPattern, namedCaptures, ThreadWatchdog.noop());
}
private Grok(Map<String, String> patternBank, String grokPattern, boolean namedCaptures, ThreadWatchdog threadWatchdog) {
this.patternBank = patternBank;
this.namedCaptures = namedCaptures;
this.threadWatchdog = threadWatchdog;
forbidCircularReferences();
String expression = toRegex(grokPattern);
byte[] expressionBytes = expression.getBytes(StandardCharsets.UTF_8);
this.compiledExpression = new Regex(expressionBytes, 0, expressionBytes.length, Option.DEFAULT, UTF8Encoding.INSTANCE);
}
/**
* Checks whether patterns reference each other in a circular manner and if so fail with an exception
*
* In a pattern, anything between <code>%{</code> and <code>}</code> or <code>:</code> is considered
* a reference to another named pattern. This method will navigate to all these named patterns and
* check for a circular reference.
*/
private void forbidCircularReferences() {
// first ensure that the pattern bank contains no simple circular references (i.e., any pattern
// containing an immediate reference to itself) as those can cause the remainder of this algorithm
// to recurse infinitely
for (Map.Entry<String, String> entry : patternBank.entrySet()) {
if (patternReferencesItself(entry.getValue(), entry.getKey())) {
throw new IllegalArgumentException("circular reference in pattern [" + entry.getKey() + "][" + entry.getValue() + "]");
}
}
// next, recursively check any other pattern names referenced in each pattern
for (Map.Entry<String, String> entry : patternBank.entrySet()) {
String name = entry.getKey();
String pattern = entry.getValue();
innerForbidCircularReferences(name, new ArrayList<>(), pattern);
}
}
private void innerForbidCircularReferences(String patternName, List<String> path, String pattern) {
if (patternReferencesItself(pattern, patternName)) {
String message;
if (path.isEmpty()) {
message = "circular reference in pattern [" + patternName + "][" + pattern + "]";
} else {
message = "circular reference in pattern [" + path.remove(path.size() - 1) + "][" + pattern +
"] back to pattern [" + patternName + "]";
// add rest of the path:
if (path.isEmpty() == false) {
message += " via patterns [" + String.join("=>", path) + "]";
}
}
throw new IllegalArgumentException(message);
}
// next check any other pattern names found in the pattern
for (int i = pattern.indexOf("%{"); i != -1; i = pattern.indexOf("%{", i + 1)) {
int begin = i + 2;
int bracketIndex = pattern.indexOf('}', begin);
int columnIndex = pattern.indexOf(':', begin);
int end;
if (bracketIndex != -1 && columnIndex == -1) {
end = bracketIndex;
} else if (columnIndex != -1 && bracketIndex == -1) {
end = columnIndex;
} else if (bracketIndex != -1 && columnIndex != -1) {
end = Math.min(bracketIndex, columnIndex);
} else {
throw new IllegalArgumentException("pattern [" + pattern + "] has circular references to other pattern definitions");
}
String otherPatternName = pattern.substring(begin, end);
path.add(otherPatternName);
innerForbidCircularReferences(patternName, path, patternBank.get(otherPatternName));
}
}
private static boolean patternReferencesItself(String pattern, String patternName) {
return pattern.contains("%{" + patternName + "}") || pattern.contains("%{" + patternName + ":");
}
public String groupMatch(String name, Region region, String pattern) {
try {
int number = GROK_PATTERN_REGEX.nameToBackrefNumber(name.getBytes(StandardCharsets.UTF_8), 0,
name.getBytes(StandardCharsets.UTF_8).length, region);
int begin = region.beg[number];
int end = region.end[number];
return new String(pattern.getBytes(StandardCharsets.UTF_8), begin, end - begin, StandardCharsets.UTF_8);
} catch (StringIndexOutOfBoundsException e) {
return null;
} catch (ValueException e) {
return null;
}
}
/**
* converts a grok expression into a named regex expression
*
* @return named regex expression
*/
public String toRegex(String grokPattern) {
byte[] grokPatternBytes = grokPattern.getBytes(StandardCharsets.UTF_8);
Matcher matcher = GROK_PATTERN_REGEX.matcher(grokPatternBytes);
int result;
try {
threadWatchdog.register();
result = matcher.search(0, grokPatternBytes.length, Option.NONE);
} finally {
threadWatchdog.unregister();
}
if (result != -1) {
Region region = matcher.getEagerRegion();
String namedPatternRef = groupMatch(NAME_GROUP, region, grokPattern);
String subName = groupMatch(SUBNAME_GROUP, region, grokPattern);
// TODO(tal): Support definitions
String definition = groupMatch(DEFINITION_GROUP, region, grokPattern);
String patternName = groupMatch(PATTERN_GROUP, region, grokPattern);
String pattern = patternBank.get(patternName);
if (pattern == null) {
throw new IllegalArgumentException("Unable to find pattern [" + patternName + "] in Grok's pattern dictionary");
}
if (pattern.contains("%{" + patternName + "}") || pattern.contains("%{" + patternName + ":")) {
throw new IllegalArgumentException("circular reference in pattern back [" + patternName + "]");
}
String grokPart;
if (namedCaptures && subName != null) {
grokPart = String.format(Locale.US, "(?<%s>%s)", namedPatternRef, pattern);
} else if (!namedCaptures) {
grokPart = String.format(Locale.US, "(?<%s>%s)", patternName + "_" + String.valueOf(result), pattern);
} else {
grokPart = String.format(Locale.US, "(?:%s)", pattern);
}
String start = new String(grokPatternBytes, 0, result, StandardCharsets.UTF_8);
String rest = new String(grokPatternBytes, region.end[0], grokPatternBytes.length - region.end[0], StandardCharsets.UTF_8);
return start + toRegex(grokPart + rest);
}
return grokPattern;
}
/**
* Checks whether a specific text matches the defined grok expression.
*
* @param text the string to match
* @return true if grok expression matches text, false otherwise.
*/
public boolean match(String text) {
Matcher matcher = compiledExpression.matcher(text.getBytes(StandardCharsets.UTF_8));
int result;
try {
threadWatchdog.register();
result = matcher.search(0, text.length(), Option.DEFAULT);
} finally {
threadWatchdog.unregister();
}
return (result != -1);
}
/**
* Matches and returns any named captures within a compiled grok expression that matched
* within the provided text.
*
* @param text the text to match and extract values from.
* @return a map containing field names and their respective coerced values that matched.
*/
public Map<String, Object> captures(String text) {
byte[] textAsBytes = text.getBytes(StandardCharsets.UTF_8);
Map<String, Object> fields = new HashMap<>();
Matcher matcher = compiledExpression.matcher(textAsBytes);
int result;
try {
threadWatchdog.register();
result = matcher.search(0, textAsBytes.length, Option.DEFAULT);
} finally {
threadWatchdog.unregister();
}
if (result == Matcher.INTERRUPTED) {
throw new RuntimeException("grok pattern matching was interrupted after [" +
threadWatchdog.maxExecutionTimeInMillis() + "] ms");
} else if (result == Matcher.FAILED) {
// TODO: I think we should throw an error here?
return null;
} else if (compiledExpression.numberOfNames() > 0) {
Region region = matcher.getEagerRegion();
for (Iterator<NameEntry> entry = compiledExpression.namedBackrefIterator(); entry.hasNext();) {
NameEntry e = entry.next();
String groupName = new String(e.name, e.nameP, e.nameEnd - e.nameP, StandardCharsets.UTF_8);
for (int number : e.getBackRefs()) {
if (region.beg[number] >= 0) {
String matchValue = new String(textAsBytes, region.beg[number], region.end[number] - region.beg[number],
StandardCharsets.UTF_8);
GrokMatchGroup match = new GrokMatchGroup(groupName, matchValue);
fields.put(match.getName(), match.getValue());
break;
}
}
}
}
return fields;
}
public static Map<String, String> getBuiltinPatterns() {
return builtinPatterns;
}
private static Map<String, String> loadBuiltinPatterns() throws IOException {
// Code for loading built-in grok patterns packaged with the jar file:
String[] PATTERN_NAMES = new String[] {
"aws", "bacula", "bro", "exim", "firewalls", "grok-patterns", "haproxy",
"java", "junos", "linux-syslog", "mcollective-patterns", "mongodb", "nagios",
"postgresql", "rails", "redis", "ruby"
};
Map<String, String> builtinPatterns = new HashMap<>();
for (String pattern : PATTERN_NAMES) {
try(InputStream is = Grok.class.getResourceAsStream("/patterns/" + pattern)) {
loadPatterns(builtinPatterns, is);
}
}
return Collections.unmodifiableMap(builtinPatterns);
}
private static void loadPatterns(Map<String, String> patternBank, InputStream inputStream) throws IOException {
String line;
BufferedReader br = new BufferedReader(new InputStreamReader(inputStream, StandardCharsets.UTF_8));
while ((line = br.readLine()) != null) {
String trimmedLine = line.replaceAll("^\\s+", "");
if (trimmedLine.startsWith("#") || trimmedLine.length() == 0) {
continue;
}
String[] parts = trimmedLine.split("\\s+", 2);
if (parts.length == 2) {
patternBank.put(parts[0], parts[1]);
}
}
}
}