/// <summary>
/// Parse the given etag value in the If-Match request header.
/// </summary>
/// <param name="etagProperties">List of etag properties for the type whose etag values we are parsing.</param>
/// <param name="ifMatchHeaderValue">value of the If-Match header as specified in the request.</param>
/// <returns>returns the etag value as a list containing the property name and its corresponding value. If the If-Match header value is '*', then returns an empty collection.</returns>
private static IEnumerable <KeyValuePair <string, object> > ParseETagValue(IList <ResourceProperty> etagProperties, string ifMatchHeaderValue)
{
Debug.Assert(etagProperties != null && etagProperties.Count != 0, "There must be atleast one etag property specified");
Debug.Assert(!String.IsNullOrEmpty(ifMatchHeaderValue), "IfMatch header cannot be null");
if (ifMatchHeaderValue == XmlConstants.HttpAnyETag)
{
// if the value is '*', then we return an empty IEnumerable.
return(WebUtil.EmptyKeyValuePairStringObject);
}
Debug.Assert(ifMatchHeaderValue.StartsWith(XmlConstants.HttpWeakETagPrefix, StringComparison.Ordinal), "If-Match header must be properly formatted - this check is done in DataService.CheckETagValues method");
Debug.Assert(ifMatchHeaderValue.Length >= XmlConstants.HttpWeakETagPrefix.Length + 1, "If-Match header must be properly formatted - this check is done in DataService.CheckETagValues method");
// Just get the etag value - we need to ignore the 'W/"' and the last '"' character from the etag
string strippedETag = ifMatchHeaderValue.Substring(XmlConstants.HttpWeakETagPrefix.Length, ifMatchHeaderValue.Length - XmlConstants.HttpWeakETagPrefix.Length - 1);
IList <object> etagValues = null;
bool success;
Exception innerException = null;
// In V1, when we didn't have IConcurrencyProvider interface, we always used to compute the
// latest etag from the entity instance we got from IUpdatable.GetResource and then comparing
// it with the If-Match request header. Hence all invalid cases always used to throw
// DataServiceException with 412, since the etags didn't match.
// In V1.5, we have added the support for IConcurrencyProvider, which means we need to parse
// the etag values and parse it to the provider, if it has implement this interface. To avoid
// breaking changes, we need to catch all parsing errors and report them as 412 instead of 400
// to avoid it from becoming a breaking change.
try
{
success = SkipTokenAndETagParser.TryParseNullableTokens(Uri.UnescapeDataString(strippedETag), out etagValues);
}
catch (DataServiceException e)
{
success = false;
innerException = e;
}
if (!success)
{
// We could have throwed BadRequest here since the etag value is not properly formattted. But since
// we used to do throw 412 in V1, keeping it that way to avoid breaking change.
throw DataServiceException.CreatePreConditionFailedError(Strings.Serializer_ETagValueDoesNotMatch, innerException);
}
if (etagValues.Count != etagProperties.Count)
{
// We could have throwed BadRequest here since the etag value is not properly formattted. But since
// we used to do throw 412 in V1, keeping it that way to avoid breaking change.
throw DataServiceException.CreatePreConditionFailedError(Strings.Serializer_ETagValueDoesNotMatch);
}
KeyValuePair <string, object>[] etagPropertyInfo = new KeyValuePair <string, object> [etagProperties.Count];
for (int i = 0; i < etagPropertyInfo.Length; i++)
{
ResourceProperty etagProperty = etagProperties[i];
object propertyValue = null;
string value = (string)etagValues[i];
if (value != XmlConstants.NullLiteralInETag)
{
// The reason we need to catch the Overflow Exception here is:
// In V1, when we didn't have IConcurrencyProvider interface, we always used to compute the
// latest etag from the entity instance we got from IUpdatable.GetResource and then comparing
// it with the If-Match request header. Hence all invalid cases always used to throw
// DataServiceException with 412, since the etags didn't match.
// In V1.5, we have added the support for IConcurrencyProvider, which means we need to parse
// the etag values and parse it to the provider, if it has implement this interface. To avoid
// breaking changes, we need to catch all parsing errors and report them as 412 instead of 400
// to avoid it from becoming a breaking change.
try
{
success = LiteralParser.ForETags.TryParseLiteral(etagProperty.Type, value, out propertyValue);
}
catch (OverflowException e)
{
success = false;
innerException = e;
}
if (!success)
{
// We could have throwed BadRequest here since the etag value is not properly formattted. But since
// we used to do throw 412 in V1, keeping it that way to avoid breaking change.
throw DataServiceException.CreatePreConditionFailedError(Strings.Serializer_ETagValueDoesNotMatch, innerException);
}
}
etagPropertyInfo[i] = new KeyValuePair <string, object>(etagProperties[i].Name, propertyValue);
}
return(etagPropertyInfo);
}
/// <summary>
/// If the provider implements IConcurrencyProvider, then this method passes the etag values
/// to the provider, otherwise compares the etag itself.
/// </summary>
/// <param name="resourceCookie">etag values for the given resource.</param>
/// <param name="container">container for the given resource.</param>
internal void SetETagValues(object resourceCookie, ResourceSetWrapper container)
{
Debug.Assert(resourceCookie != null, "resourceCookie != null");
Debug.Assert(container != null, "container != null");
AstoriaRequestMessage host = this.service.OperationContext.RequestMessage;
Debug.Assert(String.IsNullOrEmpty(host.GetRequestIfNoneMatchHeader()), "IfNoneMatch header cannot be specified for Update/Delete operations");
// Resolve the cookie first to the actual resource type
object actualEntity = this.ResolveResource(resourceCookie);
Debug.Assert(actualEntity != null, "actualEntity != null");
ResourceType resourceType = WebUtil.GetNonPrimitiveResourceType(this.service.Provider, actualEntity);
Debug.Assert(resourceType != null, "resourceType != null");
IList <ResourceProperty> etagProperties = this.service.Provider.GetETagProperties(container.Name, resourceType);
if (etagProperties.Count == 0)
{
if (!String.IsNullOrEmpty(host.GetRequestIfMatchHeader()))
{
throw DataServiceException.CreateBadRequestError(Strings.Serializer_NoETagPropertiesForType);
}
// If the type has no etag properties, then we do not need to do any etag checks
return;
}
// If the provider implements IConcurrencyProvider, then we need to call the provider
// and pass the etag values. Else, we need to compare the etag values ourselves.
IDataServiceUpdateProvider concurrencyProvider = this.updateProvider as IDataServiceUpdateProvider;
if (concurrencyProvider != null)
{
bool?checkForEquality = null;
IEnumerable <KeyValuePair <string, object> > etagValues;
if (!String.IsNullOrEmpty(host.GetRequestIfMatchHeader()))
{
checkForEquality = true;
etagValues = ParseETagValue(etagProperties, host.GetRequestIfMatchHeader());
}
else
{
etagValues = WebUtil.EmptyKeyValuePairStringObject;
}
concurrencyProvider.SetConcurrencyValues(resourceCookie, checkForEquality, etagValues);
}
else if (String.IsNullOrEmpty(host.GetRequestIfMatchHeader()))
{
throw DataServiceException.CreateBadRequestError(Strings.DataService_CannotPerformOperationWithoutETag(resourceType.FullName));
}
else if (host.GetRequestIfMatchHeader() != XmlConstants.HttpAnyETag)
{
// Compare If-Match header value with the current etag value, if the If-Match header value is not equal to '*'
string etagValue = WebUtil.GetETagValue(resourceCookie, resourceType, etagProperties, this.service, false /*getMethod*/);
Debug.Assert(!String.IsNullOrEmpty(etagValue), "etag value can never be null");
if (etagValue != host.GetRequestIfMatchHeader())
{
throw DataServiceException.CreatePreConditionFailedError(Strings.Serializer_ETagValueDoesNotMatch);
}
}
}
