Here and everywhere else PropertyManager.GetPropertyValue(context, rootDSE, PropertyManager.DnsHostName) is not returning null, instead it throws

Note it will only throw if property value is not there at all but if null value is present it will not throw and return null instead. Also note that DirectoryEntry.Properties (which this helper accesses) is public and while there is a code path guarding against null in DirectoryEntry.Properties[anyName].Value (it's a no-op) then there is nothing guarding against DirectoryEntry.Properties[anyName].Add(null).

You are right, the code is not guaranteeing against null, but somehow PropertyValueCollection[index] and PropertyValueCollection.Add(object value) both documented to be non null (it says it throws ANE for null value). Literally for all references we are suppressing the return value from (string)PropertyManager.GetPropertyValue(context, rootDSE, PropertyManager.DnsHostName)! which also illustrates the intention was non-null, there is something wrong here or we are missing something.

With that being said I am resolving this and all comments related to this, please take a look at other unrelated comments

there is nothing guarding against DirectoryEntry.Properties[anyName].Add(null)

Even it is allowing null I think setting it into null should be an error, not sure who is the expert in this area, I am OK leaving this nullable for this PR but i think we should file an issue for this

#49128

I think it shouldn't be nullable as it has defaulted to non-null and the setter is allowing null but also defaulting if the value was null, it will never be null unless set to null by constructor which might be mistake

I've initially had it this way but this can currently be null (maybe due to bug, maybe intentional):

• public DirectorySearcher(DirectoryEntry? searchRoot, string? filter, string[]? propertiesToLoad, SearchScope scope) is assigning filter directly and does not do any validation
• in Utils.cs: internal static Hashtable GetValuesWithRangeRetrieval(DirectoryEntry searchRootEntry, string? filter, ArrayList propertiesWithRangeRetrieval, ArrayList propertiesWithoutRangeRetrieval, SearchScope searchScope) is being called with explicit null from DirectoryServer.cs GetParitions() (call goes through internal static Hashtable GetValuesWithRangeRetrieval(DirectoryEntry searchRootEntry, string? filter, ArrayList propertiesToLoad, SearchScope searchScope))

I'll leave this open and turn this into an issue

(likely constructor should assign to property rather than field)

#49128

Filter seems not expected to be nullable, it defaults with nonnull when not provided, the setter is allowing null but also defaulting if the value was null, it might be an error if it is set to null by the constructor

I'll add this info to the issue above once I create it but I'd say it should handle the null given this never threw anything and there is an obvious value which should be used in place of null

#49128