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/*
* ====================================================================
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF 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.
* ====================================================================
*
* This software consists of voluntary contributions made by many
* individuals on behalf of the Apache Software Foundation. For more
* information on the Apache Software Foundation, please see
* .
*
*/
package org.apache.http.impl.client.cache;
import java.util.Date;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.http.Header;
import org.apache.http.HeaderElement;
import org.apache.http.HttpHost;
import org.apache.http.HttpRequest;
import org.apache.http.annotation.Immutable;
import org.apache.http.client.cache.HeaderConstants;
import org.apache.http.client.cache.HttpCacheEntry;
import org.apache.http.impl.cookie.DateParseException;
import org.apache.http.impl.cookie.DateUtils;
/**
* Determines whether a given {@link HttpCacheEntry} is suitable to be
* used as a response for a given {@link HttpRequest}.
*
* @since 4.1
*/
@Immutable
class CachedResponseSuitabilityChecker {
private final Log log = LogFactory.getLog(getClass());
private final boolean sharedCache;
private final boolean useHeuristicCaching;
private final float heuristicCoefficient;
private final long heuristicDefaultLifetime;
private final CacheValidityPolicy validityStrategy;
CachedResponseSuitabilityChecker(final CacheValidityPolicy validityStrategy,
CacheConfig config) {
super();
this.validityStrategy = validityStrategy;
this.sharedCache = config.isSharedCache();
this.useHeuristicCaching = config.isHeuristicCachingEnabled();
this.heuristicCoefficient = config.getHeuristicCoefficient();
this.heuristicDefaultLifetime = config.getHeuristicDefaultLifetime();
}
CachedResponseSuitabilityChecker(CacheConfig config) {
this(new CacheValidityPolicy(), config);
}
private boolean isFreshEnough(HttpCacheEntry entry, HttpRequest request, Date now) {
if (validityStrategy.isResponseFresh(entry, now)) return true;
if (useHeuristicCaching &&
validityStrategy.isResponseHeuristicallyFresh(entry, now, heuristicCoefficient, heuristicDefaultLifetime))
return true;
if (originInsistsOnFreshness(entry)) return false;
long maxstale = getMaxStale(request);
if (maxstale == -1) return false;
return (maxstale > validityStrategy.getStalenessSecs(entry, now));
}
private boolean originInsistsOnFreshness(HttpCacheEntry entry) {
if (validityStrategy.mustRevalidate(entry)) return true;
if (!sharedCache) return false;
return validityStrategy.proxyRevalidate(entry) ||
validityStrategy.hasCacheControlDirective(entry, "s-maxage");
}
private long getMaxStale(HttpRequest request) {
long maxstale = -1;
for(Header h : request.getHeaders("Cache-Control")) {
for(HeaderElement elt : h.getElements()) {
if ("max-stale".equals(elt.getName())) {
if ((elt.getValue() == null || "".equals(elt.getValue().trim()))
&& maxstale == -1) {
maxstale = Long.MAX_VALUE;
} else {
try {
long val = Long.parseLong(elt.getValue());
if (val < 0) val = 0;
if (maxstale == -1 || val < maxstale) {
maxstale = val;
}
} catch (NumberFormatException nfe) {
// err on the side of preserving semantic transparency
maxstale = 0;
}
}
}
}
}
return maxstale;
}
/**
* Determine if I can utilize a {@link HttpCacheEntry} to respond to the given
* {@link HttpRequest}
*
* @param host
* {@link HttpHost}
* @param request
* {@link HttpRequest}
* @param entry
* {@link HttpCacheEntry}
* @return boolean yes/no answer
*/
public boolean canCachedResponseBeUsed(HttpHost host, HttpRequest request, HttpCacheEntry entry, Date now) {
if (!isFreshEnough(entry, request, now)) {
log.debug("Cache entry was not fresh enough");
return false;
}
if (!validityStrategy.contentLengthHeaderMatchesActualLength(entry)) {
log.debug("Cache entry Content-Length and header information do not match");
return false;
}
if (hasUnsupportedConditionalHeaders(request)) {
log.debug("Request contained conditional headers we don't handle");
return false;
}
if (isConditional(request) && !allConditionalsMatch(request, entry, now)) {
return false;
}
for (Header ccHdr : request.getHeaders(HeaderConstants.CACHE_CONTROL)) {
for (HeaderElement elt : ccHdr.getElements()) {
if (HeaderConstants.CACHE_CONTROL_NO_CACHE.equals(elt.getName())) {
log.debug("Response contained NO CACHE directive, cache was not suitable");
return false;
}
if (HeaderConstants.CACHE_CONTROL_NO_STORE.equals(elt.getName())) {
log.debug("Response contained NO STORE directive, cache was not suitable");
return false;
}
if (HeaderConstants.CACHE_CONTROL_MAX_AGE.equals(elt.getName())) {
try {
int maxage = Integer.parseInt(elt.getValue());
if (validityStrategy.getCurrentAgeSecs(entry, now) > maxage) {
log.debug("Response from cache was NOT suitable due to max age");
return false;
}
} catch (NumberFormatException ex) {
// err conservatively
log.debug("Response from cache was malformed: " + ex.getMessage());
return false;
}
}
if (HeaderConstants.CACHE_CONTROL_MAX_STALE.equals(elt.getName())) {
try {
int maxstale = Integer.parseInt(elt.getValue());
if (validityStrategy.getFreshnessLifetimeSecs(entry) > maxstale) {
log.debug("Response from cache was not suitable due to Max stale freshness");
return false;
}
} catch (NumberFormatException ex) {
// err conservatively
log.debug("Response from cache was malformed: " + ex.getMessage());
return false;
}
}
if (HeaderConstants.CACHE_CONTROL_MIN_FRESH.equals(elt.getName())) {
try {
long minfresh = Long.parseLong(elt.getValue());
if (minfresh < 0L) return false;
long age = validityStrategy.getCurrentAgeSecs(entry, now);
long freshness = validityStrategy.getFreshnessLifetimeSecs(entry);
if (freshness - age < minfresh) {
log.debug("Response from cache was not suitable due to min fresh " +
"freshness requirement");
return false;
}
} catch (NumberFormatException ex) {
// err conservatively
log.debug("Response from cache was malformed: " + ex.getMessage());
return false;
}
}
}
}
log.debug("Response from cache was suitable");
return true;
}
/**
* Is this request the type of conditional request we support?
* @param request
* @return {@code true} if the request is supported
*/
public boolean isConditional(HttpRequest request) {
return hasSupportedEtagVadlidator(request) || hasSupportedLastModifiedValidator(request);
}
/**
* Check that conditionals that are part of this request match
* @param request
* @param entry
* @param now
* @return {@code true} if the request matches all conditionals
*/
public boolean allConditionalsMatch(HttpRequest request, HttpCacheEntry entry, Date now) {
boolean hasEtagValidator = hasSupportedEtagVadlidator(request);
boolean hasLastModifiedValidator = hasSupportedLastModifiedValidator(request);
boolean etagValidatorMatches = (hasEtagValidator) ? etagValidtorMatches(request, entry) : false;
boolean lastModifiedValidatorMatches = (hasLastModifiedValidator) ? lastModifiedValidatorMatches(request, entry, now) : false;
if ((hasEtagValidator && hasLastModifiedValidator)
&& !(etagValidatorMatches && lastModifiedValidatorMatches)) {
return false;
} else if (hasEtagValidator && !etagValidatorMatches) {
return false;
} if (hasLastModifiedValidator && !lastModifiedValidatorMatches) {
return false;
}
return true;
}
private boolean hasUnsupportedConditionalHeaders(HttpRequest request) {
return (request.getFirstHeader("If-Range") != null
|| request.getFirstHeader("If-Match") != null
|| hasValidDateField(request, "If-Unmodified-Since"));
}
private boolean hasSupportedEtagVadlidator(HttpRequest request) {
return request.containsHeader(HeaderConstants.IF_NONE_MATCH);
}
private boolean hasSupportedLastModifiedValidator(HttpRequest request) {
return hasValidDateField(request, HeaderConstants.IF_MODIFIED_SINCE);
}
/**
* Check entry against If-None-Match
* @param request
* @param entry
* @return
*/
private boolean etagValidtorMatches(HttpRequest request, HttpCacheEntry entry) {
Header etagHeader = entry.getFirstHeader(HeaderConstants.ETAG);
String etag = (etagHeader != null) ? etagHeader.getValue() : null;
Header[] ifNoneMatch = request.getHeaders(HeaderConstants.IF_NONE_MATCH);
if (ifNoneMatch != null) {
for (Header h : ifNoneMatch) {
for (HeaderElement elt : h.getElements()) {
String reqEtag = elt.toString();
if (("*".equals(reqEtag) && etag != null)
|| reqEtag.equals(etag)) {
return true;
}
}
}
}
return false;
}
/**
* Check entry against If-Modified-Since, if If-Modified-Since is in the future it is invalid as per
* http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html
* @param request
* @param entry
* @param now
* @return
*/
private boolean lastModifiedValidatorMatches(HttpRequest request, HttpCacheEntry entry, Date now) {
Header lastModifiedHeader = entry.getFirstHeader(HeaderConstants.LAST_MODIFIED);
Date lastModified = null;
try {
if(lastModifiedHeader != null) {
lastModified = DateUtils.parseDate(lastModifiedHeader.getValue());
}
} catch (DateParseException dpe) {
// nop
}
if (lastModified == null) {
return false;
}
for (Header h : request.getHeaders(HeaderConstants.IF_MODIFIED_SINCE)) {
try {
Date ifModifiedSince = DateUtils.parseDate(h.getValue());
if (ifModifiedSince.after(now) || lastModified.after(ifModifiedSince)) {
return false;
}
} catch (DateParseException dpe) {
// nop
}
}
return true;
}
private boolean hasValidDateField(HttpRequest request, String headerName) {
for(Header h : request.getHeaders(headerName)) {
try {
DateUtils.parseDate(h.getValue());
return true;
} catch (DateParseException dpe) {
// ignore malformed dates
}
}
return false;
}
}
