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/*
* SPDX-License-Identifier: Apache-2.0
*
* The OpenSearch Contributors require contributions made to
* this file be licensed under the Apache-2.0 license or a
* compatible open source license.
*/
/*
* 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.
*/
/*
* Modifications Copyright OpenSearch Contributors. See
* GitHub history for details.
*/
package org.opensearch.common.logging;
import org.opensearch.Build;
import org.opensearch.Version;
import org.opensearch.common.util.concurrent.ThreadContext;
import org.opensearch.core.common.logging.LoggerMessageFormat;
import org.opensearch.tasks.Task;
import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;
import java.util.BitSet;
import java.util.Iterator;
import java.util.Locale;
import java.util.Objects;
import java.util.Set;
import java.util.concurrent.CopyOnWriteArraySet;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
/**
* This is a simplistic logger that adds warning messages to HTTP headers.
* Use HeaderWarning.addWarning(message,params). Message will be formatted according to RFC7234.
* The result will be returned as HTTP response headers.
*
* @opensearch.internal
*/
public class HeaderWarning {
/**
* Regular expression to test if a string matches the RFC7234 specification for warning headers. This pattern assumes that the warn code
* is always 299. Further, this pattern assumes that the warn agent represents a version of OpenSearch including the build hash.
*/
public static final Pattern WARNING_HEADER_PATTERN = Pattern.compile("299 " + // warn code
"(?:Elasticsearch-|OpenSearch-)" + // warn agent (note: Elasticsearch needed for bwc mixedCluster testing)
"\\d+\\.\\d+\\.\\d+(?:-(?:alpha|beta|rc)\\d+)?(?:-SNAPSHOT)?-" + // warn agent
"(?:[a-f0-9]{7}(?:[a-f0-9]{33})?|unknown) " + // warn agent
"\"((?:\t| |!|[\\x23-\\x5B]|[\\x5D-\\x7E]|[\\x80-\\xFF]|\\\\|\\\\\")*)\"( " + // quoted warning value, captured
// quoted RFC 1123 date format
"\"" + // opening quote
"(?:Mon|Tue|Wed|Thu|Fri|Sat|Sun), " + // weekday
"\\d{2} " + // 2-digit day
"(?:Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec) " + // month
"\\d{4} " + // 4-digit year
"\\d{2}:\\d{2}:\\d{2} " + // (two-digit hour):(two-digit minute):(two-digit second)
"GMT" + // GMT
"\")?"); // closing quote (optional, since an older version can still send a warn-date)
public static final Pattern WARNING_XCONTENT_LOCATION_PATTERN = Pattern.compile("^\\[.*?]\\[-?\\d+:-?\\d+] ");
/*
* RFC7234 specifies the warning format as warn-code warn-agent "warn-text" [ "warn-date"]. Here, warn-code is a
* three-digit number with various standard warn codes specified. The warn code 299 is apt for our purposes as it represents a
* miscellaneous persistent warning (can be presented to a human, or logged, and must not be removed by a cache). The warn-agent is an
* arbitrary token; here we use the Elasticsearch version and build hash. The warn text must be quoted. The warn-date is an optional
* quoted field that can be in a variety of specified date formats; here we use RFC 1123 format.
*/
private static final String WARNING_PREFIX = String.format(
Locale.ROOT,
"299 OpenSearch-%s%s-%s",
Version.CURRENT.toString(),
Build.CURRENT.isSnapshot() ? "-SNAPSHOT" : "",
Build.CURRENT.hash()
);
private static BitSet doesNotNeedEncoding;
static {
doesNotNeedEncoding = new BitSet(1 + 0xFF);
doesNotNeedEncoding.set('\t');
doesNotNeedEncoding.set(' ');
doesNotNeedEncoding.set('!');
doesNotNeedEncoding.set('\\');
doesNotNeedEncoding.set('"');
// we have to skip '%' which is 0x25 so that it is percent-encoded too
for (int i = 0x23; i <= 0x24; i++) {
doesNotNeedEncoding.set(i);
}
for (int i = 0x26; i <= 0x5B; i++) {
doesNotNeedEncoding.set(i);
}
for (int i = 0x5D; i <= 0x7E; i++) {
doesNotNeedEncoding.set(i);
}
for (int i = 0x80; i <= 0xFF; i++) {
doesNotNeedEncoding.set(i);
}
assert doesNotNeedEncoding.get('%') == false : doesNotNeedEncoding;
}
private static final Charset UTF_8 = StandardCharsets.UTF_8;
/**
* This is set once by the {@code Node} constructor, but it uses {@link CopyOnWriteArraySet} to ensure that tests can run in parallel.
*
* Integration tests will create separate nodes within the same classloader, thus leading to a shared, {@code static} state.
* In order for all tests to appropriately be handled, this must be able to remember all {@link ThreadContext}s that it is
* given in a thread safe manner.
*
* For actual usage, multiple nodes do not share the same JVM and therefore this will only be set once in practice.
*/
static final CopyOnWriteArraySet THREAD_CONTEXT = new CopyOnWriteArraySet<>();
/**
* Set the {@link ThreadContext} used to add warning headers to network responses.
*
* This is expected to only be invoked by the {@code Node}'s constructor (therefore once outside of tests).
*
* @param threadContext The thread context owned by the {@code ThreadPool} (and implicitly a {@code Node})
* @throws IllegalStateException if this {@code threadContext} has already been set
*/
public static void setThreadContext(ThreadContext threadContext) {
Objects.requireNonNull(threadContext, "Cannot register a null ThreadContext");
// add returning false means it _did_ have it already
if (THREAD_CONTEXT.add(threadContext) == false) {
throw new IllegalStateException("Double-setting ThreadContext not allowed!");
}
}
/**
* Remove the {@link ThreadContext} used to add warning headers to network responses.
*
* This is expected to only be invoked by the {@code Node}'s {@code close} method (therefore once outside of tests).
*
* @param threadContext The thread context owned by the {@code ThreadPool} (and implicitly a {@code Node})
* @throws IllegalStateException if this {@code threadContext} is unknown (and presumably already unset before)
*/
public static void removeThreadContext(ThreadContext threadContext) {
assert threadContext != null;
// remove returning false means it did not have it already
if (THREAD_CONTEXT.remove(threadContext) == false) {
throw new IllegalStateException("Removing unknown ThreadContext not allowed!");
}
}
/**
* Extracts the warning value from the value of a warning header that is formatted according to RFC 7234. That is, given a string
* {@code 299 OpenSearch-6.0.0 "warning value"}, the return value of this method would be {@code warning value}.
*
* @param s the value of a warning header formatted according to RFC 7234.
* @return the extracted warning value
*/
public static String extractWarningValueFromWarningHeader(final String s, boolean stripXContentPosition) {
/*
* We know the exact format of the warning header, so to extract the warning value we can skip forward from the front to the first
* quote and we know the last quote is at the end of the string
*
* 299 Elasticsearch-6.0.0 "warning value"
* ^ ^
* firstQuote lastQuote
*
* We parse this manually rather than using the capturing regular expression because the regular expression involves a lot of
* backtracking and carries a performance penalty. However, when assertions are enabled, we still use the regular expression to
* verify that we are maintaining the warning header format.
*/
final int firstQuote = s.indexOf('\"');
final int lastQuote = s.length() - 1;
String warningValue = s.substring(firstQuote + 1, lastQuote);
assert assertWarningValue(s, warningValue);
if (stripXContentPosition) {
Matcher matcher = WARNING_XCONTENT_LOCATION_PATTERN.matcher(warningValue);
if (matcher.find()) {
warningValue = warningValue.substring(matcher.end());
}
}
return warningValue;
}
/**
* Assert that the specified string has the warning value equal to the provided warning value.
*
* @param s the string representing a full warning header
* @param warningValue the expected warning header
* @return {@code true} if the specified string has the expected warning value
*/
private static boolean assertWarningValue(final String s, final String warningValue) {
final Matcher matcher = WARNING_HEADER_PATTERN.matcher(s);
final boolean matches = matcher.matches();
assert matches;
return matcher.group(1).equals(warningValue);
}
/**
* Format a warning string in the proper warning format by prepending a warn code, warn agent, wrapping the warning string in quotes,
* and appending the RFC 7231 date.
*
* @param s the warning string to format
* @return a warning value formatted according to RFC 7234
*/
public static String formatWarning(final String s) {
// Assume that the common scenario won't have a string to escape and encode.
int length = WARNING_PREFIX.length() + s.length() + 3;
final StringBuilder sb = new StringBuilder(length);
sb.append(WARNING_PREFIX).append(" \"").append(escapeAndEncode(s)).append("\"");
return sb.toString();
}
/**
* Escape and encode a string as a valid RFC 7230 quoted-string.
*
* @param s the string to escape and encode
* @return the escaped and encoded string
*/
public static String escapeAndEncode(final String s) {
return encode(escapeBackslashesAndQuotes(s));
}
/**
* Escape backslashes and quotes in the specified string.
*
* @param s the string to escape
* @return the escaped string
*/
static String escapeBackslashesAndQuotes(final String s) {
/*
* We want a fast path check to avoid creating the string builder and copying characters if needed. So we walk the string looking
* for either of the characters that we need to escape. If we find a character that needs escaping, we start over and
*/
boolean escapingNeeded = false;
for (int i = 0; i < s.length(); i++) {
final char c = s.charAt(i);
if (c == '\\' || c == '"') {
escapingNeeded = true;
break;
}
}
if (escapingNeeded) {
final StringBuilder sb = new StringBuilder();
for (final char c : s.toCharArray()) {
if (c == '\\' || c == '"') {
sb.append("\\");
}
sb.append(c);
}
return sb.toString();
} else {
return s;
}
}
/**
* Encode a string containing characters outside of the legal characters for an RFC 7230 quoted-string.
*
* @param s the string to encode
* @return the encoded string
*/
static String encode(final String s) {
// first check if the string needs any encoding; this is the fast path and we want to avoid creating a string builder and copying
boolean encodingNeeded = false;
for (int i = 0; i < s.length(); i++) {
int current = s.charAt(i);
if (doesNotNeedEncoding.get(current) == false) {
encodingNeeded = true;
break;
}
}
if (encodingNeeded == false) {
return s;
}
final StringBuilder sb = new StringBuilder(s.length());
for (int i = 0; i < s.length();) {
int current = s.charAt(i);
/*
* Either the character does not need encoding or it does; when the character does not need encoding we append the character to
* a buffer and move to the next character and when the character does need encoding, we peel off as many characters as possible
* which we encode using UTF-8 until we encounter another character that does not need encoding.
*/
if (doesNotNeedEncoding.get(current)) {
// append directly and move to the next character
sb.append((char) current);
i++;
} else {
int startIndex = i;
do {
i++;
} while (i < s.length() && doesNotNeedEncoding.get(s.charAt(i)) == false);
final byte[] bytes = s.substring(startIndex, i).getBytes(UTF_8);
// noinspection ForLoopReplaceableByForEach
for (int j = 0; j < bytes.length; j++) {
sb.append('%').append(hex(bytes[j] >> 4)).append(hex(bytes[j]));
}
}
}
return sb.toString();
}
private static char hex(int b) {
final char ch = Character.forDigit(b & 0xF, 16);
if (Character.isLetter(ch)) {
return Character.toUpperCase(ch);
} else {
return ch;
}
}
public static String getXOpaqueId() {
return THREAD_CONTEXT.stream()
.filter(t -> t.getHeader(Task.X_OPAQUE_ID) != null)
.findFirst()
.map(t -> t.getHeader(Task.X_OPAQUE_ID))
.orElse("");
}
public static void addWarning(String message, Object... params) {
addWarning(THREAD_CONTEXT, message, params);
}
// package scope for testing
static void addWarning(Set threadContexts, String message, Object... params) {
final Iterator iterator = threadContexts.iterator();
if (iterator.hasNext()) {
final String formattedMessage = LoggerMessageFormat.format(message, params);
final String warningHeaderValue = formatWarning(formattedMessage);
assert WARNING_HEADER_PATTERN.matcher(warningHeaderValue).matches();
assert extractWarningValueFromWarningHeader(warningHeaderValue, false).equals(escapeAndEncode(formattedMessage));
while (iterator.hasNext()) {
try {
final ThreadContext next = iterator.next();
next.addResponseHeader("Warning", warningHeaderValue);
} catch (final IllegalStateException e) {
// ignored; it should be removed shortly
}
}
}
}
}