Introduction

Package xypriv supports to central manage and control privileges that protect resources from illegal access.

Definitions

Resources are objects that need to be protected from illegal actions.

Actions are activities which are performed on resources.

Subjects are entities who want to perform actions on resources.

There are some Subjects are considered as the owner of Resources.

How it works

The accessible ability of a subject on resource is based on:

1. The relation between subject and owner. It defines a privilege number.

The higher the privilege, the more easily the subject can access on the owner's resources.

2. The permission set of resource, it contains many elements, each element is a tuple of an owner and an access level.

The higher the access level, the more difficult a subject can access on the owner's resources.

Assuming that:

1. The resource has the owner, called O.
2. The resource defines the access level to read is AC.
3. The subject has the privilege over O is P.

The subject can read the resource if P >= AC.

Get started

After you read the following guide, please visit tutorials.

Define entities

First, you need to define all subjects, resources, contexts, and relations in each context. For example, see tutorials.

Then, give prefered names to the privileges and access levels in each context. Below items are recommended privileges and access levels for the normal context.

Privilege	Relation
10	Self
8-9	Admin
6-7	Moderator, Supporter
2-5	Familiars
1	Anyone
0	Bad relation

Permission	Level
10	Top secret
8-9	Secret
6-7	Confidential
2-5	Private
1	Public
0	Do not use

Implement Subject interface

After you read the all sections, please visit tutorials.

Subject interface requires only one method called Relation.

It receives another Subject as parameter and the context. It expects to return the privilege number of the current Subject over the parameter Subject.

The latter parameter helps to find relations depending on the context. The context can be seen as the namespace of relations.

For example, assuming that user A joined in group G, user B is the admin of group G, user C is a friend of user A:

1. In the normal context, user B has no relation with user A, user C is the friend of user A.
2. In the context of group G, user B is the group admin of user A, user C has no relation with user A.

The context will be determined by the Resource. The normal context should be represented by nil.

type Subject interface {
    Relation(s Subject, ctx any) Privilege
}

For example:

// User implements Subject interface.
type User struct {
    id string
}

func (u User) Relation(s Subject, ctx any) xypriv.Privilege {
    switch t := s.(type) {
    case User:
        if u.id == t.id {
            return xypriv.Self
        }
    }
    switch c := ctx.(type) {
    case nil:
        // handle context-dependent privileges.
    }
    return xypriv.Anyone
}

Implement Resource interfaces

After you read the all sections, please visit tutorials.

For a resource, you need to define Context and Owner methods which returns the context and owner of resource, respectively.

You also need to define Permission method, it returns the AccessLevel to perform the action on the resource. The parameter of this method depends on which problem you are solving.

type Resource interface {
    Context() any
    Owner() Subject
}

type SimpleResource interface {
    Resource
    Permission(action ...string) AccessLevel
}

type EnhancedResource interface {
    Resource
    Permission(s Subject, action ...string) AccessLevel
}

For example:

// Avatar implements SimpleResource.
type Avatar struct {
    user User
}

func (a Avatar) Context() any {
    return nil
}

fuunc (a Avatar) Owner() xypriv.Subject {
    return a.user
}

func (a Avatar) Permission(action ...string) xypriv.AccessLevel {
    if len(action) != 1 {
        return xypriv.NotSupport
    }

    switch action[0] {
    case "update":
        return xypriv.LowPrivate
    }
    return xypriv.NotSupport
}

We also provides a built-in Resource called AbstractResource. See the 3rd tutorial.

Use Check-Perform-On operator

After you read the all sections, please visit tutorials.

var userA = User{name: "A"}
var userB = User{name: "B"}

var avtA = Avatar{user: userA}

xypriv.Check(userA).Perform("update").On(avtA) // nil
xypriv.Check(userB).Perform("update").On(avtA) // XyprivError