public virtual bool AllowCacheLookup(ResponseCachingContext context)
{
var requestHeaders = context.HttpContext.Request.Headers;
var cacheControl = requestHeaders.CacheControl;
// Verify request cache-control parameters
if (!StringValues.IsNullOrEmpty(cacheControl))
{
if (HeaderUtilities.ContainsCacheDirective(cacheControl, CacheControlHeaderValue.NoCacheString))
{
context.Logger.RequestWithNoCacheNotCacheable();
return(false);
}
}
else
{
// Support for legacy HTTP 1.0 cache directive
if (HeaderUtilities.ContainsCacheDirective(requestHeaders.Pragma, CacheControlHeaderValue.NoCacheString))
{
context.Logger.RequestWithPragmaNoCacheNotCacheable();
return(false);
}
}
return(true);
}
public bool AllowCacheLookup(ResponseCachingContext context)
{
var req = context.HttpContext.Request;
// cache-control: nocache ?
if (HeaderUtilities.ContainsCacheDirective(req.Headers[HeaderNames.CacheControl], CacheControlHeaderValue.NoCacheString))
{
return(false);
}
//
return(true);
}
static bool IsResponseCacheable(HttpContext context)
{
var responseCacheControlHeader = context.Response.Headers[HeaderNames.CacheControl];
// Check response no-store
if (HeaderUtilities.ContainsCacheDirective(responseCacheControlHeader, CacheControlHeaderValue.NoStoreString))
{
return(false);
}
// Check no-cache
if (HeaderUtilities.ContainsCacheDirective(responseCacheControlHeader, CacheControlHeaderValue.NoCacheString))
{
return(false);
}
var response = context.Response;
// Do not cache responses with Set-Cookie headers
if (!StringValues.IsNullOrEmpty(response.Headers[HeaderNames.SetCookie]))
{
return(false);
}
// Do not cache responses varying by *
var varyHeader = response.Headers[HeaderNames.Vary];
if (varyHeader.Count == 1 && string.Equals(varyHeader, "*", StringComparison.OrdinalIgnoreCase))
{
return(false);
}
// Check private
if (HeaderUtilities.ContainsCacheDirective(responseCacheControlHeader, CacheControlHeaderValue.PrivateString))
{
return(false);
}
// Check response code
if (response.StatusCode != StatusCodes.Status200OK)
{
return(false);
}
// //
// context.Response.Headers[HeaderNames.CacheControl] = StringValues.Concat(CacheControlHeaderValue.SharedMaxAgeString + "=" + 60*60, responseCacheControlHeader);
//
return(true);
}
static bool AllowCacheLookup(HttpContext context)
{
var req = context.Request;
// cache-control: nocache ?
if (HeaderUtilities.ContainsCacheDirective(req.Headers[HeaderNames.CacheControl], CacheControlHeaderValue.NoCacheString))
{
return(false);
}
// logged user or posting comment:
if (req.Cookies.Any(CookieDisallowsCaching))
{
return(false);
}
//
return(true);
}
internal async Task <bool> TryServeFromCacheAsync(ResponseCachingContext context)
{
context.BaseKey = _keyProvider.CreateBaseKey(context);
var cacheEntry = await _cache.GetAsync(context.BaseKey);
var cachedVaryByRules = cacheEntry as CachedVaryByRules;
if (cachedVaryByRules != null)
{
// Request contains vary rules, recompute key(s) and try again
context.CachedVaryByRules = cachedVaryByRules;
foreach (var varyKey in _keyProvider.CreateLookupVaryByKeys(context))
{
if (await TryServeCachedResponseAsync(context, await _cache.GetAsync(varyKey)))
{
return(true);
}
}
}
else
{
if (await TryServeCachedResponseAsync(context, cacheEntry))
{
return(true);
}
}
if (HeaderUtilities.ContainsCacheDirective(context.HttpContext.Request.Headers[HeaderNames.CacheControl], CacheControlHeaderValue.OnlyIfCachedString))
{
_logger.LogGatewayTimeoutServed();
context.HttpContext.Response.StatusCode = StatusCodes.Status504GatewayTimeout;
return(true);
}
_logger.LogNoResponseServed();
return(false);
}
public virtual bool IsResponseCacheable(ResponseCachingContext context)
{
var responseCacheControlHeader = context.HttpContext.Response.Headers.CacheControl;
// Only cache pages explicitly marked with public
if (!HeaderUtilities.ContainsCacheDirective(responseCacheControlHeader, CacheControlHeaderValue.PublicString))
{
context.Logger.ResponseWithoutPublicNotCacheable();
return(false);
}
// Check response no-store
if (HeaderUtilities.ContainsCacheDirective(responseCacheControlHeader, CacheControlHeaderValue.NoStoreString))
{
context.Logger.ResponseWithNoStoreNotCacheable();
return(false);
}
// Check no-cache
if (HeaderUtilities.ContainsCacheDirective(responseCacheControlHeader, CacheControlHeaderValue.NoCacheString))
{
context.Logger.ResponseWithNoCacheNotCacheable();
return(false);
}
var response = context.HttpContext.Response;
// Do not cache responses with Set-Cookie headers
if (!StringValues.IsNullOrEmpty(response.Headers.SetCookie))
{
context.Logger.ResponseWithSetCookieNotCacheable();
return(false);
}
// Do not cache responses varying by *
var varyHeader = response.Headers.Vary;
if (varyHeader.Count == 1 && string.Equals(varyHeader, "*", StringComparison.OrdinalIgnoreCase))
{
context.Logger.ResponseWithVaryStarNotCacheable();
return(false);
}
// Check private
if (HeaderUtilities.ContainsCacheDirective(responseCacheControlHeader, CacheControlHeaderValue.PrivateString))
{
context.Logger.ResponseWithPrivateNotCacheable();
return(false);
}
// Check response code
if (response.StatusCode != StatusCodes.Status200OK)
{
context.Logger.ResponseWithUnsuccessfulStatusCodeNotCacheable(response.StatusCode);
return(false);
}
// Check response freshness
if (!context.ResponseDate.HasValue)
{
if (!context.ResponseSharedMaxAge.HasValue &&
!context.ResponseMaxAge.HasValue &&
context.ResponseTime !.Value >= context.ResponseExpires)
{
context.Logger.ExpirationExpiresExceeded(context.ResponseTime.Value, context.ResponseExpires.Value);
return(false);
}
}
else
{
var age = context.ResponseTime !.Value - context.ResponseDate.Value;
// Validate shared max age
if (age >= context.ResponseSharedMaxAge)
{
context.Logger.ExpirationSharedMaxAgeExceeded(age, context.ResponseSharedMaxAge.Value);
return(false);
}
else if (!context.ResponseSharedMaxAge.HasValue)
{
// Validate max age
if (age >= context.ResponseMaxAge)
{
context.Logger.ExpirationMaxAgeExceeded(age, context.ResponseMaxAge.Value);
return(false);
}
else if (!context.ResponseMaxAge.HasValue)
{
// Validate expiration
if (context.ResponseTime.Value >= context.ResponseExpires)
{
context.Logger.ExpirationExpiresExceeded(context.ResponseTime.Value, context.ResponseExpires.Value);
return(false);
}
}
}
}
return(true);
}
public virtual bool AllowCacheStorage(ResponseCachingContext context)
{
// Check request no-store
return(!HeaderUtilities.ContainsCacheDirective(context.HttpContext.Request.Headers.CacheControl, CacheControlHeaderValue.NoStoreString));
}
public virtual bool IsCachedEntryFresh(ResponseCachingContext context)
{
var age = context.CachedEntryAge !.Value;
var cachedCacheControlHeaders = context.CachedResponseHeaders.CacheControl;
var requestCacheControlHeaders = context.HttpContext.Request.Headers.CacheControl;
// Add min-fresh requirements
if (HeaderUtilities.TryParseSeconds(requestCacheControlHeaders, CacheControlHeaderValue.MinFreshString, out var minFresh))
{
age += minFresh.Value;
context.Logger.ExpirationMinFreshAdded(minFresh.Value);
}
// Validate shared max age, this overrides any max age settings for shared caches
TimeSpan?cachedSharedMaxAge;
HeaderUtilities.TryParseSeconds(cachedCacheControlHeaders, CacheControlHeaderValue.SharedMaxAgeString, out cachedSharedMaxAge);
if (age >= cachedSharedMaxAge)
{
// shared max age implies must revalidate
context.Logger.ExpirationSharedMaxAgeExceeded(age, cachedSharedMaxAge.Value);
return(false);
}
else if (!cachedSharedMaxAge.HasValue)
{
TimeSpan?requestMaxAge;
HeaderUtilities.TryParseSeconds(requestCacheControlHeaders, CacheControlHeaderValue.MaxAgeString, out requestMaxAge);
TimeSpan?cachedMaxAge;
HeaderUtilities.TryParseSeconds(cachedCacheControlHeaders, CacheControlHeaderValue.MaxAgeString, out cachedMaxAge);
var lowestMaxAge = cachedMaxAge < requestMaxAge ? cachedMaxAge : requestMaxAge ?? cachedMaxAge;
// Validate max age
if (age >= lowestMaxAge)
{
// Must revalidate or proxy revalidate
if (HeaderUtilities.ContainsCacheDirective(cachedCacheControlHeaders, CacheControlHeaderValue.MustRevalidateString) ||
HeaderUtilities.ContainsCacheDirective(cachedCacheControlHeaders, CacheControlHeaderValue.ProxyRevalidateString))
{
context.Logger.ExpirationMustRevalidate(age, lowestMaxAge.Value);
return(false);
}
TimeSpan?requestMaxStale;
var maxStaleExist = HeaderUtilities.ContainsCacheDirective(requestCacheControlHeaders, CacheControlHeaderValue.MaxStaleString);
HeaderUtilities.TryParseSeconds(requestCacheControlHeaders, CacheControlHeaderValue.MaxStaleString, out requestMaxStale);
// Request allows stale values with no age limit
if (maxStaleExist && !requestMaxStale.HasValue)
{
context.Logger.ExpirationInfiniteMaxStaleSatisfied(age, lowestMaxAge.Value);
return(true);
}
// Request allows stale values with age limit
if (requestMaxStale.HasValue && age - lowestMaxAge < requestMaxStale)
{
context.Logger.ExpirationMaxStaleSatisfied(age, lowestMaxAge.Value, requestMaxStale.Value);
return(true);
}
context.Logger.ExpirationMaxAgeExceeded(age, lowestMaxAge.Value);
return(false);
}
else if (!cachedMaxAge.HasValue && !requestMaxAge.HasValue)
{
// Validate expiration
DateTimeOffset expires;
if (HeaderUtilities.TryParseDate(context.CachedResponseHeaders.Expires.ToString(), out expires) &&
context.ResponseTime !.Value >= expires)
{
context.Logger.ExpirationExpiresExceeded(context.ResponseTime.Value, expires);
return(false);
}
}
}
return(true);
}
static bool AllowCacheStorage(HttpContext context)
{
// cache-control: no-store ?
return(!HeaderUtilities.ContainsCacheDirective(context.Request.Headers[HeaderNames.CacheControl], CacheControlHeaderValue.NoStoreString));
}
public void ContainsCacheDirective_MatchesExactValue(string headerValues, string targetValue, bool contains)
{
Assert.Equal(contains, HeaderUtilities.ContainsCacheDirective(new StringValues(headerValues), targetValue));
}
