On Wed, 8 Jan 2025 16:50:01 GMT, Martin Balao <mba...@openjdk.org> wrote:
>> In addition to the goals, scope, motivation, specification and requirement >> notes in [JDK-8315487](https://bugs.openjdk.org/browse/JDK-8315487), we >> would like to describe the most relevant decisions taken during the >> implementation of this enhancement. These notes are organized by feature, >> may encompass more than one file or code segment, and are aimed to provide a >> high-level view of this PR. >> >> ## ProvidersFilter >> >> ### Filter construction (parser) >> >> The providers filter is constructed from a string value, taken from either a >> system or a security property with name "jdk.security.providers.filter". >> This process occurs at sun.security.jca.ProvidersFilter class —simply >> referred as ProvidersFilter onward— static initialization. Thus, changes to >> the filter's overridable property are not effective afterwards and no >> assumptions should be made regarding when this class gets initialized. >> >> The filter's string value is processed with a custom parser of order 'n', >> being 'n' the number of characters. The parser, represented by the >> ProvidersFilter.Parser class, can be characterized as a Deterministic Finite >> Automaton (DFA). The ProvidersFilter.Parser::parse method is the starting >> point to get characters from the filter's string value and generate state >> transitions in the parser's internal state-machine. See >> ProvidersFilter.Parser::nextState for more details about the parser's states >> and both valid and invalid transitions. The ParsingState enum defines valid >> parser states and Transition the reasons to move between states. If a filter >> string cannot be parsed, a ProvidersFilter.ParserException exception is >> thrown, and turned into an unchecked IllegalArgumentException in the >> ProvidersFilter.Filter constructor. >> >> While we analyzed —and even tried, at early stages of the development— the >> use of regular expressions for filter parsing, we discarded the approach in >> order to get maximum performance, support a more advanced syntax and have >> flexibility for further extensions in the future. >> >> ### Filter (structure and behavior) >> >> A filter is represented by the ProvidersFilter.Filter class. It consists of >> an ordered list of rules, returned by the parser, that represents filter >> patterns from left to right (see the filter syntax for reference). At the >> end of this list, a match-all and deny rule is added for default behavior. >> When a service is evaluated against the filter, each filter rule is checked >> in the ProvidersFilter.Filter::apply method. The rule makes an all... > > Martin Balao has updated the pull request incrementally with one additional > commit since the last revision: > > Copyright date update. > > Co-authored-by: Martin Balao Alonso <mba...@redhat.com> > Co-authored-by: Francisco Ferrari Bihurriet <fferr...@redhat.com> I have been starting to review the code, and am initially reviewing this with respect to how it complies with the current API specification. All of the JCA API `getInstance` methods that do not have a provider argument have text like the following: > This method traverses the list of registered security Providers, starting > with the most preferred Provider. A new `<service>` object encapsulating the > `<service>Spi` implementation from the first provider that supports the > specified algorithm is returned. However, the providers filter can be configured to prevent that object from being returned. I think this is an important difference in behavior that it should be documented as an implementation note. My initial suggestion is something like the following: "The JDK Reference Implementation additionally uses the `jdk.security.providers.filter` system and security property to determine which services are enabled. A provider whose <service> algorithm is not enabled will not be selected." I think similar text will need to be added in the `Provider` API, but I need to review those changes more closely first. ------------- PR Comment: https://git.openjdk.org/jdk/pull/15539#issuecomment-2611086422
