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/*
* Copyright (C) 2014-2017 Apple Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
* THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "config.h"
#include "CacheValidation.h"
#include "CookieJar.h"
#include "HTTPHeaderMap.h"
#include "NetworkStorageSession.h"
#include "ResourceRequest.h"
#include "ResourceResponse.h"
#include "SameSiteInfo.h"
#include <wtf/Optional.h>
#include <wtf/Vector.h>
#include <wtf/text/StringView.h>
#include <wtf/text/WTFString.h>
namespace WebCore {
// These response headers are not copied from a revalidated response to the
// cached response headers. For compatibility, this list is based on Chromium's
// net/http/http_response_headers.cc.
static const char* const headersToIgnoreAfterRevalidation[] = {
"allow",
"connection",
"etag",
"keep-alive",
"last-modified",
"proxy-authenticate",
"proxy-connection",
"trailer",
"transfer-encoding",
"upgrade",
"www-authenticate",
"x-frame-options",
"x-xss-protection",
};
// Some header prefixes mean "Don't copy this header from a 304 response.".
// Rather than listing all the relevant headers, we can consolidate them into
// this list, also grabbed from Chromium's net/http/http_response_headers.cc.
static const char* const headerPrefixesToIgnoreAfterRevalidation[] = {
"content-",
"x-content-",
"x-webkit-"
};
static inline bool shouldUpdateHeaderAfterRevalidation(const String& header)
{
for (auto& headerToIgnore : headersToIgnoreAfterRevalidation) {
if (equalIgnoringASCIICase(header, headerToIgnore))
return false;
}
for (auto& prefixToIgnore : headerPrefixesToIgnoreAfterRevalidation) {
// FIXME: Would be more efficient if we added an overload of
// startsWithIgnoringASCIICase that takes a const char*.
if (header.startsWithIgnoringASCIICase(prefixToIgnore))
return false;
}
return true;
}
void updateResponseHeadersAfterRevalidation(ResourceResponse& response, const ResourceResponse& validatingResponse)
{
// Freshening stored response upon validation:
// http://tools.ietf.org/html/rfc7234#section-4.3.4
for (const auto& header : validatingResponse.httpHeaderFields()) {
// Entity headers should not be sent by servers when generating a 304
// response; misconfigured servers send them anyway. We shouldn't allow
// such headers to update the original request. We'll base this on the
// list defined by RFC2616 7.1, with a few additions for extension headers
// we care about.
if (!shouldUpdateHeaderAfterRevalidation(header.key))
continue;
response.setHTTPHeaderField(header.key, header.value);
}
}
Seconds computeCurrentAge(const ResourceResponse& response, WallTime responseTime)
{
// Age calculation:
// http://tools.ietf.org/html/rfc7234#section-4.2.3
// No compensation for latency as that is not terribly important in practice.
auto dateValue = response.date();
auto apparentAge = dateValue ? std::max(0_us, responseTime - *dateValue) : 0_us;
auto ageValue = response.age().valueOr(0_us);
auto correctedInitialAge = std::max(apparentAge, ageValue);
auto residentTime = WallTime::now() - responseTime;
return correctedInitialAge + residentTime;
}
Seconds computeFreshnessLifetimeForHTTPFamily(const ResourceResponse& response, WallTime responseTime)
{
if (!response.url().protocolIsInHTTPFamily())
return 0_us;
// Freshness Lifetime:
// http://tools.ietf.org/html/rfc7234#section-4.2.1
auto maxAge = response.cacheControlMaxAge();
if (maxAge)
return *maxAge;
auto date = response.date();
auto effectiveDate = date.valueOr(responseTime);
if (auto expires = response.expires())
return *expires - effectiveDate;
// Implicit lifetime.
switch (response.httpStatusCode()) {
case 301: // Moved Permanently
case 410: // Gone
// These are semantically permanent and so get long implicit lifetime.
return 24_h * 365;
default:
// Heuristic Freshness:
// http://tools.ietf.org/html/rfc7234#section-4.2.2
if (auto lastModified = response.lastModified())
return (effectiveDate - *lastModified) * 0.1;
return 0_us;
}
}
void updateRedirectChainStatus(RedirectChainCacheStatus& redirectChainCacheStatus, const ResourceResponse& response)
{
if (redirectChainCacheStatus.status == RedirectChainCacheStatus::Status::NotCachedRedirection)
return;
if (response.cacheControlContainsNoStore() || response.cacheControlContainsNoCache() || response.cacheControlContainsMustRevalidate()) {
redirectChainCacheStatus.status = RedirectChainCacheStatus::Status::NotCachedRedirection;
return;
}
redirectChainCacheStatus.status = RedirectChainCacheStatus::Status::CachedRedirection;
auto responseTimestamp = WallTime::now();
// Store the nearest end of cache validity date
auto endOfValidity = responseTimestamp + computeFreshnessLifetimeForHTTPFamily(response, responseTimestamp) - computeCurrentAge(response, responseTimestamp);
redirectChainCacheStatus.endOfValidity = std::min(redirectChainCacheStatus.endOfValidity, endOfValidity);
}
bool redirectChainAllowsReuse(RedirectChainCacheStatus redirectChainCacheStatus, ReuseExpiredRedirectionOrNot reuseExpiredRedirection)
{
switch (redirectChainCacheStatus.status) {
case RedirectChainCacheStatus::Status::NoRedirection:
return true;
case RedirectChainCacheStatus::Status::NotCachedRedirection:
return false;
case RedirectChainCacheStatus::Status::CachedRedirection:
return reuseExpiredRedirection || WallTime::now() <= redirectChainCacheStatus.endOfValidity;
}
ASSERT_NOT_REACHED();
return false;
}
inline bool isCacheHeaderSeparator(UChar c)
{
// http://tools.ietf.org/html/rfc7230#section-3.2.6
switch (c) {
case '(':
case ')':
case '<':
case '>':
case '@':
case ',':
case ';':
case ':':
case '\\':
case '"':
case '/':
case '[':
case ']':
case '?':
case '=':
case '{':
case '}':
case ' ':
case '\t':
return true;
default:
return false;
}
}
inline bool isControlCharacterOrSpace(UChar character)
{
return character <= ' ' || character == 127;
}
inline StringView trimToNextSeparator(StringView string)
{
return string.substring(0, string.find(isCacheHeaderSeparator));
}
static Vector<std::pair<String, String>> parseCacheHeader(const String& header)
{
Vector<std::pair<String, String>> result;
String safeHeaderString = header.removeCharacters(isControlCharacterOrSpace);
StringView safeHeader = safeHeaderString;
unsigned max = safeHeader.length();
unsigned pos = 0;
while (pos < max) {
size_t nextCommaPosition = safeHeader.find(',', pos);
size_t nextEqualSignPosition = safeHeader.find('=', pos);
if (nextEqualSignPosition == notFound && nextCommaPosition == notFound) {
// Add last directive to map with empty string as value
result.append({ trimToNextSeparator(safeHeader.substring(pos, max - pos)).toString(), emptyString() });
return result;
}
if (nextCommaPosition != notFound && (nextCommaPosition < nextEqualSignPosition || nextEqualSignPosition == notFound)) {
// Add directive to map with empty string as value
result.append({ trimToNextSeparator(safeHeader.substring(pos, nextCommaPosition - pos)).toString(), emptyString() });
pos += nextCommaPosition - pos + 1;
continue;
}
// Get directive name, parse right hand side of equal sign, then add to map
String directive = trimToNextSeparator(safeHeader.substring(pos, nextEqualSignPosition - pos)).toString();
pos += nextEqualSignPosition - pos + 1;
StringView value = safeHeader.substring(pos, max - pos);
if (value[0] == '"') {
// The value is a quoted string
size_t nextDoubleQuotePosition = value.find('"', 1);
if (nextDoubleQuotePosition == notFound) {
// Parse error; just use the rest as the value
result.append({ directive, trimToNextSeparator(value.substring(1)).toString() });
return result;
}
// Store the value as a quoted string without quotes
result.append({ directive, value.substring(1, nextDoubleQuotePosition - 1).toString() });
pos += (safeHeader.find('"', pos) - pos) + nextDoubleQuotePosition + 1;
// Move past next comma, if there is one
size_t nextCommaPosition2 = safeHeader.find(',', pos);
if (nextCommaPosition2 == notFound)
return result; // Parse error if there is anything left with no comma
pos += nextCommaPosition2 - pos + 1;
continue;
}
// The value is a token until the next comma
size_t nextCommaPosition2 = value.find(',');
if (nextCommaPosition2 == notFound) {
// The rest is the value; no change to value needed
result.append({ directive, trimToNextSeparator(value).toString() });
return result;
}
// The value is delimited by the next comma
result.append({ directive, trimToNextSeparator(value.substring(0, nextCommaPosition2)).toString() });
pos += (safeHeader.find(',', pos) - pos) + 1;
}
return result;
}
CacheControlDirectives parseCacheControlDirectives(const HTTPHeaderMap& headers)
{
CacheControlDirectives result;
String cacheControlValue = headers.get(HTTPHeaderName::CacheControl);
if (!cacheControlValue.isEmpty()) {
auto directives = parseCacheHeader(cacheControlValue);
size_t directivesSize = directives.size();
for (size_t i = 0; i < directivesSize; ++i) {
// A no-cache directive with a value is only meaningful for proxy caches.
// It should be ignored by a browser level cache.
// http://tools.ietf.org/html/rfc7234#section-5.2.2.2
if (equalLettersIgnoringASCIICase(directives[i].first, "no-cache") && directives[i].second.isEmpty())
result.noCache = true;
else if (equalLettersIgnoringASCIICase(directives[i].first, "no-store"))
result.noStore = true;
else if (equalLettersIgnoringASCIICase(directives[i].first, "must-revalidate"))
result.mustRevalidate = true;
else if (equalLettersIgnoringASCIICase(directives[i].first, "max-age")) {
if (result.maxAge) {
// First max-age directive wins if there are multiple ones.
continue;
}
bool ok;
double maxAge = directives[i].second.toDouble(&ok);
if (ok)
result.maxAge = Seconds { maxAge };
} else if (equalLettersIgnoringASCIICase(directives[i].first, "max-stale")) {
// https://tools.ietf.org/html/rfc7234#section-5.2.1.2
if (result.maxStale) {
// First max-stale directive wins if there are multiple ones.
continue;
}
if (directives[i].second.isEmpty()) {
// if no value is assigned to max-stale, then the client is willing to accept a stale response of any age.
result.maxStale = Seconds::infinity();
continue;
}
bool ok;
double maxStale = directives[i].second.toDouble(&ok);
if (ok)
result.maxStale = Seconds { maxStale };
} else if (equalLettersIgnoringASCIICase(directives[i].first, "immutable"))
result.immutable = true;
}
}
if (!result.noCache) {
// Handle Pragma: no-cache
// This is deprecated and equivalent to Cache-control: no-cache
// Don't bother tokenizing the value; handling that exactly right is not important.
result.noCache = headers.get(HTTPHeaderName::Pragma).containsIgnoringASCIICase("no-cache");
}
return result;
}
static String cookieRequestHeaderFieldValue(const NetworkStorageSession& session, const ResourceRequest& request)
{
return session.cookieRequestHeaderFieldValue(request.firstPartyForCookies(), SameSiteInfo::create(request), request.url(), WTF::nullopt, WTF::nullopt, request.url().protocolIs("https") ? IncludeSecureCookies::Yes : IncludeSecureCookies::No).first;
}
static String cookieRequestHeaderFieldValue(const CookieJar* cookieJar, const PAL::SessionID& sessionID, const ResourceRequest& request)
{
if (!cookieJar)
return { };
return cookieJar->cookieRequestHeaderFieldValue(sessionID, request.firstPartyForCookies(), SameSiteInfo::create(request), request.url(), WTF::nullopt, WTF::nullopt, request.url().protocolIs("https") ? IncludeSecureCookies::Yes : IncludeSecureCookies::No).first;
}
static String headerValueForVary(const ResourceRequest& request, const String& headerName, Function<String()>&& cookieRequestHeaderFieldValueFunction)
{
// Explicit handling for cookies is needed because they are added magically by the networking layer.
// FIXME: The value might have changed between making the request and retrieving the cookie here.
// We could fetch the cookie when making the request but that seems overkill as the case is very rare and it
// is a blocking operation. This should be sufficient to cover reasonable cases.
if (headerName == httpHeaderNameString(HTTPHeaderName::Cookie))
return cookieRequestHeaderFieldValueFunction();
return request.httpHeaderField(headerName);
}
static Vector<std::pair<String, String>> collectVaryingRequestHeadersInternal(const ResourceResponse& response, Function<String(const String& headerName)>&& headerValueForVaryFunction)
{
String varyValue = response.httpHeaderField(HTTPHeaderName::Vary);
if (varyValue.isEmpty())
return { };
Vector<String> varyingHeaderNames = varyValue.split(',');
Vector<std::pair<String, String>> varyingRequestHeaders;
varyingRequestHeaders.reserveCapacity(varyingHeaderNames.size());
for (auto& varyHeaderName : varyingHeaderNames) {
String headerName = varyHeaderName.stripWhiteSpace();
String headerValue = headerValueForVaryFunction(headerName);
varyingRequestHeaders.append(std::make_pair(headerName, headerValue));
}
return varyingRequestHeaders;
}
Vector<std::pair<String, String>> collectVaryingRequestHeaders(NetworkStorageSession& storageSession, const ResourceRequest& request, const ResourceResponse& response)
{
return collectVaryingRequestHeadersInternal(response, [&] (const String& headerName) {
return headerValueForVary(request, headerName, [&] {
return cookieRequestHeaderFieldValue(storageSession, request);
});
});
}
Vector<std::pair<String, String>> collectVaryingRequestHeaders(const CookieJar* cookieJar, const ResourceRequest& request, const ResourceResponse& response, const PAL::SessionID& sessionID)
{
return collectVaryingRequestHeadersInternal(response, [&] (const String& headerName) {
return headerValueForVary(request, headerName, [&] {
return cookieRequestHeaderFieldValue(cookieJar, sessionID, request);
});
});
}
static bool verifyVaryingRequestHeadersInternal(const Vector<std::pair<String, String>>& varyingRequestHeaders, Function<String(const String&)>&& headerValueForVary)
{
for (auto& varyingRequestHeader : varyingRequestHeaders) {
// FIXME: Vary: * in response would ideally trigger a cache delete instead of a store.
if (varyingRequestHeader.first == "*")
return false;
if (headerValueForVary(varyingRequestHeader.first) != varyingRequestHeader.second)
return false;
}
return true;
}
bool verifyVaryingRequestHeaders(NetworkStorageSession& storageSession, const Vector<std::pair<String, String>>& varyingRequestHeaders, const ResourceRequest& request)
{
return verifyVaryingRequestHeadersInternal(varyingRequestHeaders, [&] (const String& headerName) {
return headerValueForVary(request, headerName, [&] {
return cookieRequestHeaderFieldValue(storageSession, request);
});
});
}
bool verifyVaryingRequestHeaders(const CookieJar* cookieJar, const Vector<std::pair<String, String>>& varyingRequestHeaders, const ResourceRequest& request, const PAL::SessionID& sessionID)
{
return verifyVaryingRequestHeadersInternal(varyingRequestHeaders, [&] (const String& headerName) {
return headerValueForVary(request, headerName, [&] {
return cookieRequestHeaderFieldValue(cookieJar, sessionID, request);
});
});
}
// http://tools.ietf.org/html/rfc7231#page-48
bool isStatusCodeCacheableByDefault(int statusCode)
{
switch (statusCode) {
case 200: // OK
case 203: // Non-Authoritative Information
case 204: // No Content
case 206: // Partial Content
case 300: // Multiple Choices
case 301: // Moved Permanently
case 404: // Not Found
case 405: // Method Not Allowed
case 410: // Gone
case 414: // URI Too Long
case 501: // Not Implemented
return true;
default:
return false;
}
}
bool isStatusCodePotentiallyCacheable(int statusCode)
{
switch (statusCode) {
case 201: // Created
case 202: // Accepted
case 205: // Reset Content
case 302: // Found
case 303: // See Other
case 307: // Temporary redirect
case 403: // Forbidden
case 406: // Not Acceptable
case 415: // Unsupported Media Type
return true;
default:
return false;
}
}
}