//引入命名空间
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Linq.Expressions;
using System.Security.Claims;
using System.Xml;

namespace ClaimsAuthorizationLibrary
{
    /// <summary>
    /// Simple ClaimsAuthorizationManager implementation that reads policy information from the .config file
    /// </summary>
    public class MyClaimsAuthorizationManager : ClaimsAuthorizationManager
    {
        static Dictionary<ResourceAction, Func<ClaimsPrincipal, bool>> _policies = new Dictionary<ResourceAction, Func<ClaimsPrincipal, bool>>();
        PolicyReader _policyReader = new PolicyReader();

        /// <summary>
        /// Creates a new instance of the MyClaimsAuthorizationManager
        /// </summary>        
        public MyClaimsAuthorizationManager()
        {
        }

        /// <summary>
        /// Overloads  the base class method to load the custom policies from the config file
        /// </summary>
        /// <param name="nodelist">XmlNodeList containing the policy information read from the config file</param>
        public override void LoadCustomConfiguration(XmlNodeList nodelist)
        {
            Expression<Func<ClaimsPrincipal, bool>> policyExpression;

            foreach (XmlNode node in nodelist)
            {
                //
                // Initialize the policy cache
                //
                XmlDictionaryReader rdr = XmlDictionaryReader.CreateDictionaryReader(new XmlTextReader(new StringReader(node.OuterXml)));
                rdr.MoveToContent();

                string resource = rdr.GetAttribute("resource");
                string action = rdr.GetAttribute("action");

                policyExpression = _policyReader.ReadPolicy(rdr);

                //
                // Compile the policy expression into a function
                //
                Func<ClaimsPrincipal, bool> policy = policyExpression.Compile();

                //
                // Insert the policy function into the policy cache
                //
                _policies[new ResourceAction(resource, action)] = policy;
            }
        }

        /// <summary>
        /// Checks if the principal specified in the authorization context is authorized to perform action specified in the authorization context 
        /// on the specified resoure
        /// </summary>
        /// <param name="pec">Authorization context</param>
        /// <returns>true if authorized, false otherwise</returns>
        public override bool CheckAccess(AuthorizationContext pec)
        {
            //
            // Evaluate the policy against the claims of the 
            // principal to determine access
            //
            bool access = false;
            try
            {
                ResourceAction ra = new ResourceAction(pec.Resource.First<Claim>().Value, pec.Action.First<Claim>().Value);

                access = _policies[ra](pec.Principal);
            }
            catch (Exception)
            {
                access = false;
            }

            return access;
        }
    }
}

//引入命名空间
using System;

namespace ClaimsAuthorizationLibrary
{
    /// <summary>
    /// Class to encapsulate resource/action pair
    /// </summary>
    public class ResourceAction
    {
        public string Resource;
        public string Action;

        /// <summary>
        /// Checks if the current instance is equal to the given object by comparing the resource and action values
        /// </summary>
        /// <param name="obj">object to compare to</param>
        /// <returns>True if equal, else false.</returns>
        public override bool Equals(object obj)
        {
            ResourceAction ra = obj as ResourceAction;
            if (ra != null)
            {
                return ((string.Compare(ra.Resource, Resource, true) == 0) && (string.Compare(ra.Action, Action, true) == 0));
            }

            return base.Equals(obj);
        }

        /// <summary>
        /// Gets the hash code.
        /// </summary>
        /// <returns>The hash code.</returns>
        public override int GetHashCode()
        {
            return (Resource + Action).ToLower().GetHashCode();
        }

        /// <summary>
        /// Creates an instance of ResourceAction class.
        /// </summary>
        /// <param name="resource">The resource name.</param>
        /// <param name="action">The action.</param>
        /// <exception cref="ArgumentNullException">when <paramref name="resource"/> is null</exception>
        public ResourceAction(string resource, string action)
        {
            if (string.IsNullOrEmpty(resource))
            {
                throw new ArgumentNullException("resource");
            }

            Resource = resource;
            Action = action;
        }
    }
}