public static CacheResponseDirective ReadCacheResponseDirective(this HttpResponseMessage responseMessage)
{
var directive = new CacheResponseDirective();
var cacheControl = responseMessage.Headers.CacheControl;
if (cacheControl != null)
{
directive.MustRevalidate = cacheControl.MustRevalidate;
directive.NoCache = cacheControl.NoCache;
// TODO deal with no-cache field names?
directive.NoStore = cacheControl.NoStore;
// TODO deal with no-transform?
directive.Public = cacheControl.Public;
directive.Private = cacheControl.Private;
// TODO deal with private field names?
// TODO deal with proxy-revalidate?
directive.MaxAge = cacheControl.MaxAge;
directive.SharedMaxAge = cacheControl.SharedMaxAge;
// TODO deal with cacheControl.Extensions
}
// TODO handle Expires, Age, Date
directive.LastModified = responseMessage.Content?.Headers.LastModified;
directive.ETag = responseMessage.Headers.ETag.ToETag();
// TODO handle responseMessage.Headers.Vary;
// TODO handle responseMessage.Headers.Warning;
return directive;
}
public void AppliesDirectiveToResponse()
{
var dateTime1 = new DateTimeOffset(2015, 10, 20, 15, 42, 31, TimeSpan.Zero);
var response = new TestableHttpResponse();
var cacheResponseDirective = new CacheResponseDirective();
cacheResponseDirective.LastModified = dateTime1;
cacheResponseDirective.MaxAge = TimeSpan.FromMinutes(15);
cacheResponseDirective.MustRevalidate = true;
cacheResponseDirective.NoCache = true;
cacheResponseDirective.NoStore = true;
cacheResponseDirective.Private = true;
cacheResponseDirective.Public = true;
cacheResponseDirective.SharedMaxAge = TimeSpan.FromHours(1);
DnxExtensions.ApplyCacheResponseDirective(response, cacheResponseDirective);
var responseHeaders = response.GetTypedHeaders();
Assert.NotNull(responseHeaders.CacheControl);
Assert.Equal(dateTime1, responseHeaders.LastModified);
Assert.Equal(TimeSpan.FromMinutes(15), responseHeaders.CacheControl.MaxAge);
Assert.True(responseHeaders.CacheControl.MustRevalidate);
Assert.True(responseHeaders.CacheControl.NoCache);
Assert.True(responseHeaders.CacheControl.NoStore);
Assert.True(responseHeaders.CacheControl.Private);
Assert.True(responseHeaders.CacheControl.Public);
Assert.Equal(TimeSpan.FromHours(1), responseHeaders.CacheControl.SharedMaxAge);
}
public static void ApplyCacheResponseDirective(this HttpResponse response, CacheResponseDirective directive)
{
var cacheControl = new CacheControlHeaderValue();
cacheControl.MaxAge = directive.MaxAge;
cacheControl.MustRevalidate = directive.MustRevalidate;
cacheControl.NoCache = directive.NoCache;
cacheControl.NoStore = directive.NoStore;
cacheControl.Private = directive.Private;
cacheControl.Public = directive.Public;
cacheControl.SharedMaxAge = directive.SharedMaxAge;
var responseHeaders = response.GetTypedHeaders();
responseHeaders.CacheControl = cacheControl;
responseHeaders.LastModified = directive.LastModified;
responseHeaders.ETag = directive.ETag.ToETagHeaderValue();
}
/// <summary>
/// Combines two <see cref="CacheResponseDirective"/> instances into a new one, using the most restrictive value from each pair of input properties.
/// </summary>
/// <remarks>
/// <see cref="LastModified"/> is only set if both inputs specify a value.
/// <see cref="Public"/> is only set if the result does not have <see cref="Private"/> set.
/// </remarks>
public static CacheResponseDirective Combine(CacheResponseDirective a, CacheResponseDirective b, Func<ETag, ETag, ETag> etagCombiner = null)
{
var result = new CacheResponseDirective();
if (a.LastModified.HasValue && b.LastModified.HasValue)
{
// Only set LastModified if both sides specify it. If either side does not specify then LastModified of the combined result is indeterminate.
result.LastModified = Max(a.LastModified, b.LastModified);
}
result.MaxAge = Min(a.MaxAge, b.MaxAge);
result.MustRevalidate = a.MustRevalidate || b.MustRevalidate;
result.NoCache = a.NoCache || b.NoCache;
result.NoStore = a.NoStore || b.NoStore;
result.Private = a.Private || b.Private;
result.Public = !result.Private && (a.Public || b.Public); // TODO: Is this correct? Does it make sense for a response to be marked both as Public and Private?
result.SharedMaxAge = Min(a.SharedMaxAge, b.SharedMaxAge);
if (etagCombiner != null && a.ETag != null && b.ETag != null)
result.ETag = etagCombiner(a.ETag, b.ETag);
return result;
}