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using System;
using System.Collections.Generic;
using System.Text;
namespace OpenSim.Framework.PolicyManager
{
#region ACL Core Class
/// <summary>
/// Access Control List Engine
/// </summary>
public class ACL
{
Dictionary<string, Role> Roles = new Dictionary<string, Role>();
Dictionary<string, Resource> Resources = new Dictionary<string, Resource>();
public ACL AddRole(Role role)
{
if (Roles.ContainsKey(role.Name))
throw new AlreadyContainsRoleException(role);
Roles.Add(role.Name, role);
return this;
}
public ACL AddResource(Resource resource)
{
Resources.Add(resource.Name, resource);
return this;
}
public Permission HasPermission(string role, string resource)
{
if (!Roles.ContainsKey(role))
throw new KeyNotFoundException();
if (!Resources.ContainsKey(resource))
throw new KeyNotFoundException();
return Roles[role].RequestPermission(resource);
}
public ACL GrantPermission(string role, string resource)
{
if (!Roles.ContainsKey(role))
throw new KeyNotFoundException();
if (!Resources.ContainsKey(resource))
throw new KeyNotFoundException();
Roles[role].GivePermission(resource, Permission.Allow);
return this;
}
public ACL DenyPermission(string role, string resource)
{
if (!Roles.ContainsKey(role))
throw new KeyNotFoundException();
if (!Resources.ContainsKey(resource))
throw new KeyNotFoundException();
Roles[role].GivePermission(resource, Permission.Deny);
return this;
}
public ACL ResetPermission(string role, string resource)
{
if (!Roles.ContainsKey(role))
throw new KeyNotFoundException();
if (!Resources.ContainsKey(resource))
throw new KeyNotFoundException();
Roles[role].GivePermission(resource, Permission.None);
return this;
}
}
#endregion
#region Exceptions
/// <summary>
/// Thrown when an ACL attempts to add a duplicate role.
/// </summary>
public class AlreadyContainsRoleException : Exception
{
protected Role m_role;
public Role ErrorRole
{
get { return m_role; }
}
public AlreadyContainsRoleException(Role role)
{
m_role = role;
}
public override string ToString()
{
return "This ACL already contains a role called '" + m_role.Name + "'.";
}
}
#endregion
#region Roles and Resources
/// <summary>
/// Does this Role have permission to access a specified Resource?
/// </summary>
public enum Permission { Deny, None, Allow };
/// <summary>
/// A role class, for use with Users or Groups
/// </summary>
public class Role
{
private string m_name;
private Role[] m_parents;
private Dictionary<string, Permission> m_resources = new Dictionary<string, Permission>();
public string Name
{
get { return m_name; }
}
public Permission RequestPermission(string resource)
{
return RequestPermission(resource, Permission.None);
}
public Permission RequestPermission(string resource, Permission current)
{
// Deny permissions always override any others
if (current == Permission.Deny)
return current;
Permission temp = Permission.None;
// Pickup non-None permissions
if (m_resources.ContainsKey(resource) && m_resources[resource] != Permission.None)
temp = m_resources[resource];
if (m_parents != null)
{
foreach (Role parent in m_parents)
{
temp = parent.RequestPermission(resource, temp);
}
}
return temp;
}
public void GivePermission(string resource, Permission perm)
{
m_resources[resource] = perm;
}
public Role(string name)
{
m_name = name;
m_parents = null;
}
public Role(string name, Role[] parents)
{
m_name = name;
m_parents = parents;
}
}
public class Resource
{
private string m_name;
public string Name
{
get { return m_name; }
}
public Resource(string name)
{
m_name = name;
}
}
#endregion
#region Tests
class ACLTester
{
public ACLTester()
{
ACL acl = new ACL();
Role Guests = new Role("Guests");
acl.AddRole(Guests);
Role[] parents = new Role[0];
parents[0] = Guests;
Role JoeGuest = new Role("JoeGuest", parents);
acl.AddRole(JoeGuest);
Resource CanBuild = new Resource("CanBuild");
acl.AddResource(CanBuild);
acl.GrantPermission("Guests", "CanBuild");
acl.HasPermission("JoeGuest", "CanBuild");
}
}
#endregion
}
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