/*
For a given httpRequest
1) If AlwaysNetwork, return
2) If we have a cache entry for this url populate headers so the server can return 304
3) Calculate if response_is_fresh and if so send the cache and set loadedFromCache to true
*/
void QNetworkAccessHttpBackend::validateCache(QHttpNetworkRequest &httpRequest, bool &loadedFromCache)
{
QNetworkRequest::CacheLoadControl CacheLoadControlAttribute =
(QNetworkRequest::CacheLoadControl)request().attribute(QNetworkRequest::CacheLoadControlAttribute, QNetworkRequest::PreferNetwork).toInt();
if (CacheLoadControlAttribute == QNetworkRequest::AlwaysNetwork) {
// forced reload from the network
// tell any caching proxy servers to reload too
httpRequest.setHeaderField("Cache-Control", "no-cache");
httpRequest.setHeaderField("Pragma", "no-cache");
return;
}
QAbstractNetworkCache *nc = networkCache();
if (!nc)
return; // no local cache
QNetworkCacheMetaData metaData = nc->metaData(url());
if (!metaData.isValid())
return; // not in cache
if (!metaData.saveToDisk())
return;
QNetworkHeadersPrivate cacheHeaders;
QNetworkHeadersPrivate::RawHeadersList::ConstIterator it;
cacheHeaders.setAllRawHeaders(metaData.rawHeaders());
it = cacheHeaders.findRawHeader("etag");
if (it != cacheHeaders.rawHeaders.constEnd())
httpRequest.setHeaderField("If-None-Match", it->second);
QDateTime lastModified = metaData.lastModified();
if (lastModified.isValid())
httpRequest.setHeaderField("If-Modified-Since", QNetworkHeadersPrivate::toHttpDate(lastModified));
it = cacheHeaders.findRawHeader("Cache-Control");
if (it != cacheHeaders.rawHeaders.constEnd()) {
QHash<QByteArray, QByteArray> cacheControl = parseHttpOptionHeader(it->second);
if (cacheControl.contains("must-revalidate"))
return;
}
/*
* age_value
* is the value of Age: header received by the cache with
* this response.
* date_value
* is the value of the origin server's Date: header
* request_time
* is the (local) time when the cache made the request
* that resulted in this cached response
* response_time
* is the (local) time when the cache received the
* response
* now
* is the current (local) time
*/
QDateTime currentDateTime = QDateTime::currentDateTime();
int age_value = 0;
it = cacheHeaders.findRawHeader("age");
if (it != cacheHeaders.rawHeaders.constEnd())
age_value = QNetworkHeadersPrivate::fromHttpDate(it->second).toTime_t();
int date_value = 0;
it = cacheHeaders.findRawHeader("date");
if (it != cacheHeaders.rawHeaders.constEnd())
date_value = QNetworkHeadersPrivate::fromHttpDate(it->second).toTime_t();
int now = currentDateTime.toUTC().toTime_t();
int request_time = now;
int response_time = now;
int apparent_age = qMax(0, response_time - date_value);
int corrected_received_age = qMax(apparent_age, age_value);
int response_delay = response_time - request_time;
int corrected_initial_age = corrected_received_age + response_delay;
int resident_time = now - response_time;
int current_age = corrected_initial_age + resident_time;
// RFC 2616 13.2.4 Expiration Calculations
QDateTime expirationDate = metaData.expirationDate();
if (!expirationDate.isValid()) {
if (lastModified.isValid()) {
int diff = currentDateTime.secsTo(lastModified);
expirationDate = lastModified;
expirationDate.addSecs(diff / 10);
if (httpRequest.headerField("Warning").isEmpty()) {
QDateTime dt;
dt.setTime_t(current_age);
if (dt.daysTo(currentDateTime) > 1)
httpRequest.setHeaderField("Warning", "113");
}
}
}
int freshness_lifetime = currentDateTime.secsTo(expirationDate);
bool response_is_fresh = (freshness_lifetime > current_age);
if (!response_is_fresh && CacheLoadControlAttribute == QNetworkRequest::PreferNetwork)
return;
loadedFromCache = true;
#if defined(QNETWORKACCESSHTTPBACKEND_DEBUG)
qDebug() << "response_is_fresh" << CacheLoadControlAttribute;
#endif
if (!sendCacheContents(metaData))
loadedFromCache = false;
}
void QNetworkAccessHttpBackend::replyHeaderChanged()
{
// reconstruct the HTTP header
QList<QPair<QByteArray, QByteArray> > headerMap = httpReply->header();
QList<QPair<QByteArray, QByteArray> >::ConstIterator it = headerMap.constBegin(),
end = headerMap.constEnd();
QByteArray header;
for (; it != end; ++it) {
QByteArray value = rawHeader(it->first);
if (!value.isEmpty()) {
if (it->first.toLower() == "set-cookie")
value += "\n";
else
value += ", ";
}
value += it->second;
setRawHeader(it->first, value);
}
setAttribute(QNetworkRequest::HttpStatusCodeAttribute, httpReply->statusCode());
setAttribute(QNetworkRequest::HttpReasonPhraseAttribute, httpReply->reasonPhrase());
// is it a redirection?
const int statusCode = httpReply->statusCode();
checkForRedirect(statusCode);
if (statusCode >= 500 && statusCode < 600) {
QAbstractNetworkCache *nc = networkCache();
if (nc) {
QNetworkCacheMetaData metaData = nc->metaData(url());
QNetworkHeadersPrivate cacheHeaders;
cacheHeaders.setAllRawHeaders(metaData.rawHeaders());
QNetworkHeadersPrivate::RawHeadersList::ConstIterator it;
it = cacheHeaders.findRawHeader("Cache-Control");
bool mustReValidate = false;
if (it != cacheHeaders.rawHeaders.constEnd()) {
QHash<QByteArray, QByteArray> cacheControl = parseHttpOptionHeader(it->second);
if (cacheControl.contains("must-revalidate"))
mustReValidate = true;
}
if (!mustReValidate && sendCacheContents(metaData))
return;
}
}
if (statusCode == 304) {
#if defined(QNETWORKACCESSHTTPBACKEND_DEBUG)
qDebug() << "Received a 304 from" << url();
#endif
QAbstractNetworkCache *nc = networkCache();
if (nc) {
QNetworkCacheMetaData oldMetaData = nc->metaData(url());
QNetworkCacheMetaData metaData = fetchCacheMetaData(oldMetaData);
if (oldMetaData != metaData)
nc->updateMetaData(metaData);
if (sendCacheContents(metaData))
return;
}
}
if (statusCode != 304 && statusCode != 303) {
if (!isCachingEnabled())
setCachingEnabled(true);
}
metaDataChanged();
}
/*
For a given httpRequest
1) If AlwaysNetwork, return
2) If we have a cache entry for this url populate headers so the server can return 304
3) Calculate if response_is_fresh and if so send the cache and set loadedFromCache to true
*/
bool QNetworkAccessHttpBackend::loadFromCacheIfAllowed(QHttpNetworkRequest &httpRequest)
{
QNetworkRequest::CacheLoadControl CacheLoadControlAttribute =
(QNetworkRequest::CacheLoadControl)request().attribute(QNetworkRequest::CacheLoadControlAttribute, QNetworkRequest::PreferNetwork).toInt();
if (CacheLoadControlAttribute == QNetworkRequest::AlwaysNetwork) {
// If the request does not already specify preferred cache-control
// force reload from the network and tell any caching proxy servers to reload too
if (!request().rawHeaderList().contains("Cache-Control")) {
httpRequest.setHeaderField("Cache-Control", "no-cache");
httpRequest.setHeaderField("Pragma", "no-cache");
}
return false;
}
// The disk cache API does not currently support partial content retrieval.
// That is why we don't use the disk cache for any such requests.
if (request().hasRawHeader("Range"))
return false;
QAbstractNetworkCache *nc = networkCache();
if (!nc)
return false; // no local cache
QNetworkCacheMetaData metaData = nc->metaData(url());
if (!metaData.isValid())
return false; // not in cache
if (!metaData.saveToDisk())
return false;
QNetworkHeadersPrivate cacheHeaders;
QNetworkHeadersPrivate::RawHeadersList::ConstIterator it;
cacheHeaders.setAllRawHeaders(metaData.rawHeaders());
it = cacheHeaders.findRawHeader("etag");
if (it != cacheHeaders.rawHeaders.constEnd())
httpRequest.setHeaderField("If-None-Match", it->second);
QDateTime lastModified = metaData.lastModified();
if (lastModified.isValid())
httpRequest.setHeaderField("If-Modified-Since", QNetworkHeadersPrivate::toHttpDate(lastModified));
it = cacheHeaders.findRawHeader("Cache-Control");
if (it != cacheHeaders.rawHeaders.constEnd()) {
QHash<QByteArray, QByteArray> cacheControl = parseHttpOptionHeader(it->second);
if (cacheControl.contains("must-revalidate"))
return false;
}
QDateTime currentDateTime = QDateTime::currentDateTime();
QDateTime expirationDate = metaData.expirationDate();
#if 0
/*
* age_value
* is the value of Age: header received by the cache with
* this response.
* date_value
* is the value of the origin server's Date: header
* request_time
* is the (local) time when the cache made the request
* that resulted in this cached response
* response_time
* is the (local) time when the cache received the
* response
* now
* is the current (local) time
*/
int age_value = 0;
it = cacheHeaders.findRawHeader("age");
if (it != cacheHeaders.rawHeaders.constEnd())
age_value = it->second.toInt();
QDateTime dateHeader;
int date_value = 0;
it = cacheHeaders.findRawHeader("date");
if (it != cacheHeaders.rawHeaders.constEnd()) {
dateHeader = QNetworkHeadersPrivate::fromHttpDate(it->second);
date_value = dateHeader.toTime_t();
}
int now = currentDateTime.toUTC().toTime_t();
int request_time = now;
int response_time = now;
// Algorithm from RFC 2616 section 13.2.3
int apparent_age = qMax(0, response_time - date_value);
int corrected_received_age = qMax(apparent_age, age_value);
int response_delay = response_time - request_time;
int corrected_initial_age = corrected_received_age + response_delay;
int resident_time = now - response_time;
int current_age = corrected_initial_age + resident_time;
// RFC 2616 13.2.4 Expiration Calculations
if (!expirationDate.isValid()) {
if (lastModified.isValid()) {
int diff = currentDateTime.secsTo(lastModified);
expirationDate = lastModified;
expirationDate.addSecs(diff / 10);
if (httpRequest.headerField("Warning").isEmpty()) {
QDateTime dt;
dt.setTime_t(current_age);
if (dt.daysTo(currentDateTime) > 1)
httpRequest.setHeaderField("Warning", "113");
}
}
}
// the cache-saving code below sets the expirationDate with date+max_age
// if "max-age" is present, or to Expires otherwise
int freshness_lifetime = dateHeader.secsTo(expirationDate);
bool response_is_fresh = (freshness_lifetime > current_age);
#else
bool response_is_fresh = currentDateTime.secsTo(expirationDate) >= 0;
#endif
if (!response_is_fresh)
return false;
#if defined(QNETWORKACCESSHTTPBACKEND_DEBUG)
qDebug() << "response_is_fresh" << CacheLoadControlAttribute;
#endif
return sendCacheContents(metaData);
}
