internal Func <HttpRequestMessage, Task <HttpResponseMessage> > GetIfModifiedUnmodifiedSince()
{
return((request) =>
{
try
{
if (request.Method != HttpMethod.Get)
{
return null;
}
DateTimeOffset?ifModifiedSince = request.Headers.IfModifiedSince;
DateTimeOffset?ifUnmodifiedSince = request.Headers.IfUnmodifiedSince;
if (ifModifiedSince == null && ifUnmodifiedSince == null)
{
return null; // no etag
}
if (ifModifiedSince != null && ifUnmodifiedSince != null) // both exist
{
return request.CreateResponse(HttpStatusCode.BadRequest)
.ToTask();
}
bool ifModified = (ifUnmodifiedSince == null);
DateTimeOffset modifiedInQuestion = ifModified ? ifModifiedSince.Value : ifUnmodifiedSince.Value;
var entityTagKey = GenerateCacheKey(request);
TimedEntityTagHeaderValue actualEtag = null;
bool isModified = true;
if (_entityTagStore.TryGetValue(entityTagKey, out actualEtag))
{
isModified = actualEtag.LastModified > modifiedInQuestion;
}
return isModified ^ ifModified
? new NotModifiedResponse(request, actualEtag.ToEntityTagHeaderValue()).ToTask()
: null;
}
catch (Exception e)
{
throw new CacheCowServerException("Error in GetIfModifiedUnmodifiedSince", e);
}
});
}
internal Func <HttpRequestMessage, Task <HttpResponseMessage> > GetIfMatchNoneMatch()
{
return((request) =>
{
if (request.Method != HttpMethod.Get)
{
return null;
}
ICollection <EntityTagHeaderValue> noneMatchTags = request.Headers.IfNoneMatch;
ICollection <EntityTagHeaderValue> matchTags = request.Headers.IfMatch;
if (matchTags.Count == 0 && noneMatchTags.Count == 0)
{
return null; // no etag
}
if (matchTags.Count > 0 && noneMatchTags.Count > 0) // both if-match and if-none-match exist
{
return request.CreateResponse(HttpStatusCode.BadRequest)
.ToTask();
}
var isNoneMatch = noneMatchTags.Count > 0;
var etags = isNoneMatch ? noneMatchTags : matchTags;
var entityTagKey = GenerateCacheKey(request);
// compare the Etag with the one in the cache
// do conditional get.
TimedEntityTagHeaderValue actualEtag = null;
bool matchFound = false;
if (_entityTagStore.TryGetValue(entityTagKey, out actualEtag))
{
if (etags.Any(etag => etag.Tag == actualEtag.Tag))
{
matchFound = true;
}
}
return matchFound ^ isNoneMatch ? null : new NotModifiedResponse(request,
actualEtag.ToEntityTagHeaderValue()).ToTask();
});
}
