public CachingHandler(ICacheStore cacheStore)
{
_cacheStore = cacheStore;
VaryHeaderStore = new InMemoryVaryHeaderStore();
DefaultVaryHeaders = new string[]{"Accept"};
}
public CachingHandler(ICacheStore cacheStore)
{
_cacheStore = cacheStore;
UseConditionalPut = true;
VaryHeaderStore = new InMemoryVaryHeaderStore();
DefaultVaryHeaders = new string[]{"Accept"};
ResponseValidator = (response) =>
{
// 13.4
//Unless specifically constrained by a cache-control (section 14.9) directive, a caching system MAY always store
// a successful response (see section 13.8) as a cache entry, MAY return it without validation if it
// is fresh, and MAY return it after successful validation. If there is neither a cache validator nor an
// explicit expiration time associated with a response, we do not expect it to be cached, but certain caches MAY violate this expectation
// (for example, when little or no network connectivity is available).
if (!response.StatusCode.IsIn(_cacheableStatuses))
return ResponseValidationResult.NotCacheable;
if (!response.IsSuccessStatusCode || response.Headers.CacheControl == null ||
response.Headers.CacheControl.NoStore || response.Headers.CacheControl.NoCache)
return ResponseValidationResult.NotCacheable;
response.Headers.Date = response.Headers.Date ?? DateTimeOffset.UtcNow; // this also helps in cache creation
var dateTimeOffset = response.Headers.Date;
if(response.Content == null)
return ResponseValidationResult.NotCacheable;
if (response.Headers.CacheControl.MaxAge == null &&
response.Headers.CacheControl.SharedMaxAge == null &&
response.Content.Headers.Expires == null)
return ResponseValidationResult.NotCacheable;
if (response.Content.Headers.Expires != null &&
response.Content.Headers.Expires < DateTimeOffset.UtcNow)
return response.Headers.CacheControl.MustRevalidate ? ResponseValidationResult.MustRevalidate : ResponseValidationResult.Stale;
if (response.Headers.CacheControl.MaxAge != null &&
DateTimeOffset.UtcNow > response.Headers.Date.Value.Add(response.Headers.CacheControl.MaxAge.Value))
return response.Headers.CacheControl.MustRevalidate ? ResponseValidationResult.MustRevalidate : ResponseValidationResult.Stale;
if (response.Headers.CacheControl.SharedMaxAge != null &&
DateTimeOffset.UtcNow > response.Headers.Date.Value.Add(response.Headers.CacheControl.SharedMaxAge.Value))
return response.Headers.CacheControl.MustRevalidate ? ResponseValidationResult.MustRevalidate : ResponseValidationResult.Stale;
return ResponseValidationResult.OK;
};
_ignoreRequestRules = (request) =>
{
if (!request.Method.IsIn(HttpMethod.Get, HttpMethod.Put))
return true;
// client can tell CachingHandler not to do caching for a particular request
if(request.Headers.CacheControl!=null)
{
if (request.Headers.CacheControl.NoCache || request.Headers.CacheControl.NoStore)
return true;
}
return false;
};
ResponseStoragePreparationRules = (response) =>
{
// 14.9.3
// If a response includes both an Expires header and a max-age directive,
// the max-age directive overrides the Expires header, even if the Expires header is more restrictive.
if(response.Content.Headers.Expires!=null &&
(response.Headers.CacheControl.MaxAge != null || response.Headers.CacheControl.SharedMaxAge!=null))
{
response.Content.Headers.Expires = null;
}
};
}
public CachingHandler(ICacheStore cacheStore)
{
_cacheStore = cacheStore;
UseConditionalPut = true;
MustRevalidateByDefault = true;
VaryHeaderStore = new InMemoryVaryHeaderStore();
DefaultVaryHeaders = new string[]{"Accept"};
ResponseValidator = (response) =>
{
// 13.4
//Unless specifically constrained by a cache-control (section 14.9) directive, a caching system MAY always store
// a successful response (see section 13.8) as a cache entry, MAY return it without validation if it
// is fresh, and MAY return it after successful validation. If there is neither a cache validator nor an
// explicit expiration time associated with a response, we do not expect it to be cached, but certain caches MAY violate this expectation
// (for example, when little or no network connectivity is available).
// 14.9.1
// If the no-cache directive does not specify a field-name, then a cache MUST NOT use the response to satisfy a subsequent request without
// successful revalidation with the origin server. This allows an origin server to prevent caching
// even by caches that have been configured to return stale responses to client requests.
//If the no-cache directive does specify one or more field-names, then a cache MAY use the response
// to satisfy a subsequent request, subject to any other restrictions on caching. However, the specified
// field-name(s) MUST NOT be sent in the response to a subsequent request without successful revalidation
// with the origin server. This allows an origin server to prevent the re-use of certain header fields in a response, while still allowing caching of the rest of the response.
if (!response.StatusCode.IsIn(_cacheableStatuses))
return ResponseValidationResult.NotCacheable;
if (!response.IsSuccessStatusCode || response.Headers.CacheControl == null ||
response.Headers.CacheControl.NoStore) // || response.Headers.CacheControl.NoCache was removed. See issue
return ResponseValidationResult.NotCacheable;
response.Headers.Date = response.Headers.Date ?? DateTimeOffset.UtcNow; // this also helps in cache creation
var dateTimeOffset = response.Headers.Date;
if(response.Content == null)
return ResponseValidationResult.NotCacheable;
if (response.Headers.CacheControl.MaxAge == null &&
response.Headers.CacheControl.SharedMaxAge == null &&
response.Content.Headers.Expires == null)
return ResponseValidationResult.NotCacheable;
if(response.Headers.CacheControl.NoCache)
return ResponseValidationResult.MustRevalidate;
// here we use
if (response.Content.Headers.Expires != null &&
response.Content.Headers.Expires < DateTimeOffset.UtcNow)
return response.Headers.CacheControl.ShouldRevalidate(MustRevalidateByDefault)
? ResponseValidationResult.MustRevalidate : ResponseValidationResult.Stale;
if (response.Headers.CacheControl.MaxAge != null &&
DateTimeOffset.UtcNow > response.Headers.Date.Value.Add(response.Headers.CacheControl.MaxAge.Value))
return response.Headers.CacheControl.ShouldRevalidate(MustRevalidateByDefault)
? ResponseValidationResult.MustRevalidate : ResponseValidationResult.Stale;
if (response.Headers.CacheControl.SharedMaxAge != null &&
DateTimeOffset.UtcNow > response.Headers.Date.Value.Add(response.Headers.CacheControl.SharedMaxAge.Value))
return response.Headers.CacheControl.ShouldRevalidate(MustRevalidateByDefault)
? ResponseValidationResult.MustRevalidate : ResponseValidationResult.Stale;
return ResponseValidationResult.OK;
};
_ignoreRequestRules = (request) =>
{
if (!request.Method.IsIn(HttpMethod.Get, HttpMethod.Put))
return true;
// client can tell CachingHandler not to do caching for a particular request
if(request.Headers.CacheControl!=null)
{
if (request.Headers.CacheControl.NoStore)
return true;
}
return false;
};
ResponseStoragePreparationRules = (response) =>
{
// 14.9.3
// If a response includes both an Expires header and a max-age directive,
// the max-age directive overrides the Expires header, even if the Expires header is more restrictive.
if(response.Content.Headers.Expires!=null &&
(response.Headers.CacheControl.MaxAge != null || response.Headers.CacheControl.SharedMaxAge!=null))
{
response.Content.Headers.Expires = null;
}
};
}
