mlhpdx/radiusdictionarieslib

A .Net Core class library for working with RADIUS attributes and VSAs as types.

RADIUS Dictionaries Library for .Net Core

Working with RADIUS attributes requires closely following the RFCs as well as vendor-defined rules for encoding the content of AAA packets. Typically, software is written to use the so-called "RADIUS Dictionaries" as generic dictionary data structures. This library provides a different approach, with each attribute being a type that can be easily used with the pattern matching capabilities of C# 8 (switch expressions, for example). Perhaps not for everyone, but perhaps prefered by some.

Usage

This library is distributed as a Nuget package hosted here at github. I may clone it to nuget.org as well at a later date, but for now follow github's instructions to setup a new source.

Now, just add the package to your existing project:

dotnet add package RadiusDictionariesLib

Next, some code. Let's say you are a vendor and want to make sure that your code only makes use of your own VSA's. Well, you can do that:

public void DoTheThing(IArubaAttribute attr) {
    // attr is strongly-typed to be one of the attributes defined in Aruba's dictionary.
    // ...
}

Or, if you want to vary control-flow based on attribute types with C# 8 pattern matching:

string GetTheThing(IRadiusAttribute attr) {
    return attr switch {
        IVendorSpecificAttribute vsa => vsa switch {
            IArubaAttribute => "Aruba calling...",
            {} => "I'm a VSA"
        },
        UserName u => $"It's {u.Value}",
        UserPassword => "Shhh.",
    };
}

To make it easy to do the right thing, where attribute values are defined in a dictionary this library will include them as an attribute-specific enumeration that makes it more difficult to "do the wrong thing" by assigning invalid values to or misinterpreting them. For example:

void BeSafe(Hp.ManagementProtocol attr) {
    // is "HTTP" represented by a 5 or 6? I can never remember...
    if (attr.Value == Hp.ManagementProtocolValue.Http) throw new SecurityException("Nope.");
}

Likewise, where a type is specified for attribute values (e.g. octets, string, integer, etc.) the Value field of the attribute will match:

void TypeSafeValues() {
	var user = new UserName() { Value = "lee" }; // works fine
	var chap = new ChapPassword() { Value = "Password1!" }; // won't compile (requires ArraySegment<byte>)
	var bandwith = new SessionTimeout() { Value = -10 }; // won't compile (value must be unsigned)
	var framedip = new FramedAddress() { Value = IPAddress.Any }; // works fine
}

Building

This project builds like a straight-forward .Net Core project. First, clone the code:

git clone https://github.com/mlhpdx/RadiusDictionariesLib.git radiusdictionarieslib && cd radiusdictionarieslib

Then build, which will automatically run code-generation (T4) on the dictionary files and produce the library:

dotnet build

Run tests, if you'd like:

dotnet test

Versions and Continuous Builds

This library is auto-generated from the FreeRADIUS project's dictionaries (see their repo) text files. Once CI/CD is fully figured-out new commits to the master branch over there will cause this project to automatically build, test and publish a new "preview" package version.

The versioning of preview packages will make use of the FreeRADIUS commit ID as part of the suffix, so the two can be correllated. When a new release of FreeRADIUS is tagged, a "production" version of the RadiusDictionariesLib nuget will be produced with a matching version. If this versioning strategy causes you problems, please file an issue so we can work it out.

Roadmap

I'll add more to this library, perhaps including:

• Cardinality (from the various specifications, not provided in dictionaries)
• Parsing (just attributes, mapping byte buffers to attribute instances)
• Rules checks (content, format, cardinality, etc. for sets of attributes)

This library isn't the right place for things that relate to the RADIUS protocol itself (servers, clients, etc.).

Enjoy!