ETagUtils.java
/*
* JBoss, Home of Professional Open Source.
* Copyright 2014 Red Hat, Inc., and individual contributors
* as indicated by the @author tags.
*
* Licensed 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 io.undertow.util;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import io.undertow.server.HttpServerExchange;
/**
* @author Stuart Douglas
*/
public class ETagUtils {
private static final char COMMA = ',';
private static final char QUOTE = '"';
private static final char W = 'W';
private static final char SLASH = '/';
/**
* Handles the if-match header. returns true if the request should proceed, false otherwise
*
* @param exchange the exchange
* @param etag The etags
* @return
*/
public static boolean handleIfMatch(final HttpServerExchange exchange, final ETag etag, boolean allowWeak) {
return handleIfMatch(exchange, Collections.singletonList(etag), allowWeak);
}
/**
* Handles the if-match header. returns true if the request should proceed, false otherwise
*
* @param exchange the exchange
* @param etags The etags
* @return
*/
public static boolean handleIfMatch(final HttpServerExchange exchange, final List<ETag> etags, boolean allowWeak) {
return handleIfMatch(exchange.getRequestHeaders().getFirst(Headers.IF_MATCH), etags, allowWeak);
}
/**
* Handles the if-match header. returns true if the request should proceed, false otherwise
*
* @param ifMatch The if match header
* @param etag The etags
* @return
*/
public static boolean handleIfMatch(final String ifMatch, final ETag etag, boolean allowWeak) {
return handleIfMatch(ifMatch, Collections.singletonList(etag), allowWeak);
}
/**
* Handles the if-match header. returns true if the request should proceed, false otherwise
*
* @param ifMatch The ifMatch header
* @param etags The etags
* @return
*/
public static boolean handleIfMatch(final String ifMatch, final List<ETag> etags, boolean allowWeak) {
if (ifMatch == null) {
return true;
}
if (ifMatch.equals("*")) {
return true; //todo: how to tell if there is a current entity for the request
}
List<ETag> parts = parseETagList(ifMatch);
for (ETag part : parts) {
if (part.isWeak() && !allowWeak) {
continue;
}
for (ETag tag : etags) {
if (tag != null) {
if (tag.isWeak() && !allowWeak) {
continue;
}
if (tag.getTag().equals(part.getTag())) {
return true;
}
}
}
}
return false;
}
/**
* Handles the if-none-match header. returns true if the request should proceed, false otherwise
*
* @param exchange the exchange
* @param etag The etags
* @return
*/
public static boolean handleIfNoneMatch(final HttpServerExchange exchange, final ETag etag, boolean allowWeak) {
return handleIfNoneMatch(exchange, Collections.singletonList(etag), allowWeak);
}
/**
* Handles the if-none-match header. returns true if the request should proceed, false otherwise
*
* @param exchange the exchange
* @param etags The etags
* @return
*/
public static boolean handleIfNoneMatch(final HttpServerExchange exchange, final List<ETag> etags, boolean allowWeak) {
return handleIfNoneMatch(exchange.getRequestHeaders().getFirst(Headers.IF_NONE_MATCH), etags, allowWeak);
}
/**
* Handles the if-none-match header. returns true if the request should proceed, false otherwise
*
* @param ifNoneMatch the header
* @param etag The etags
* @return
*/
public static boolean handleIfNoneMatch(final String ifNoneMatch, final ETag etag, boolean allowWeak) {
return handleIfNoneMatch(ifNoneMatch, Collections.singletonList(etag), allowWeak);
}
/**
* Handles the if-none-match header. returns true if the request should proceed, false otherwise
*
* @param ifNoneMatch the header
* @param etags The etags
* @return
*/
public static boolean handleIfNoneMatch(final String ifNoneMatch, final List<ETag> etags, boolean allowWeak) {
if (ifNoneMatch == null) {
return true;
}
List<ETag> parts = parseETagList(ifNoneMatch);
for (ETag part : parts) {
if (part.getTag().equals("*")) {
return false;
}
if (part.isWeak() && !allowWeak) {
continue;
}
for (ETag tag : etags) {
if (tag != null) {
if (tag.isWeak() && !allowWeak) {
continue;
}
if (tag.getTag().equals(part.getTag())) {
return false;
}
}
}
}
return true;
}
public static List<ETag> parseETagList(final String header) {
char[] headerChars = header.toCharArray();
// The LinkedHashMap is used so that the parameter order can also be retained.
List<ETag> response = new ArrayList<>();
SearchingFor searchingFor = SearchingFor.START_OF_VALUE;
int valueStart = 0;
boolean weak = false;
boolean malformed = false;
for (int i = 0; i < headerChars.length; i++) {
switch (searchingFor) {
case START_OF_VALUE:
if (headerChars[i] != COMMA && !Character.isWhitespace(headerChars[i])) {
if (headerChars[i] == QUOTE) {
valueStart = i + 1;
searchingFor = SearchingFor.LAST_QUOTE;
weak = false;
malformed = false;
} else if (headerChars[i] == W) {
searchingFor = SearchingFor.WEAK_SLASH;
}
}
break;
case WEAK_SLASH:
if (headerChars[i] == QUOTE) {
valueStart = i + 1;
searchingFor = SearchingFor.LAST_QUOTE;
weak = true;
malformed = false;
} else if (headerChars[i] != SLASH) {
malformed = true;
searchingFor = SearchingFor.END_OF_VALUE;
}
break;
case LAST_QUOTE:
if (headerChars[i] == QUOTE) {
String value = String.valueOf(headerChars, valueStart, i - valueStart);
response.add(new ETag(weak, value.trim()));
searchingFor = SearchingFor.START_OF_VALUE;
}
break;
case END_OF_VALUE:
if (headerChars[i] == COMMA || Character.isWhitespace(headerChars[i])) {
if (!malformed) {
String value = String.valueOf(headerChars, valueStart, i - valueStart);
response.add(new ETag(weak, value.trim()));
searchingFor = SearchingFor.START_OF_VALUE;
}
}
break;
}
}
if (searchingFor == SearchingFor.END_OF_VALUE || searchingFor == SearchingFor.LAST_QUOTE) {
if (!malformed) {
// Special case where we reached the end of the array containing the header values.
String value = String.valueOf(headerChars, valueStart, headerChars.length - valueStart);
response.add(new ETag(weak, value.trim()));
}
}
return response;
}
/**
* @param exchange The exchange
* @return The ETag for the exchange, or null if the etag is not set
*/
public static ETag getETag(final HttpServerExchange exchange) {
final String tag = exchange.getResponseHeaders().getFirst(Headers.ETAG);
if (tag == null) {
return null;
}
char[] headerChars = tag.toCharArray();
SearchingFor searchingFor = SearchingFor.START_OF_VALUE;
int valueStart = 0;
boolean weak = false;
boolean malformed = false;
for (int i = 0; i < headerChars.length; i++) {
switch (searchingFor) {
case START_OF_VALUE:
if (headerChars[i] != COMMA && !Character.isWhitespace(headerChars[i])) {
if (headerChars[i] == QUOTE) {
valueStart = i + 1;
searchingFor = SearchingFor.LAST_QUOTE;
weak = false;
malformed = false;
} else if (headerChars[i] == W) {
searchingFor = SearchingFor.WEAK_SLASH;
}
}
break;
case WEAK_SLASH:
if (headerChars[i] == QUOTE) {
valueStart = i + 1;
searchingFor = SearchingFor.LAST_QUOTE;
weak = true;
malformed = false;
} else if (headerChars[i] != SLASH) {
return null; //malformed
}
break;
case LAST_QUOTE:
if (headerChars[i] == QUOTE) {
String value = String.valueOf(headerChars, valueStart, i - valueStart);
return new ETag(weak, value.trim());
}
break;
case END_OF_VALUE:
if (headerChars[i] == COMMA || Character.isWhitespace(headerChars[i])) {
if (!malformed) {
String value = String.valueOf(headerChars, valueStart, i - valueStart);
return new ETag(weak, value.trim());
}
}
break;
}
}
if (searchingFor == SearchingFor.END_OF_VALUE || searchingFor == SearchingFor.LAST_QUOTE) {
if (!malformed) {
// Special case where we reached the end of the array containing the header values.
String value = String.valueOf(headerChars, valueStart, headerChars.length - valueStart);
return new ETag(weak, value.trim());
}
}
return null;
}
enum SearchingFor {
START_OF_VALUE, LAST_QUOTE, END_OF_VALUE, WEAK_SLASH;
}
}