Zone.cs

using System.Runtime.InteropServices;
using System.Runtime.Serialization;
using System.Security.Permissions;

namespace System.Security.Policy
{
    [Serializable]
    [ComVisible(true)]
    public sealed class Zone : EvidenceBase, IIdentityPermissionFactory
    {
        [OptionalField(VersionAdded = 2)]
        private string m_url;

        private SecurityZone m_zone;

        private static readonly string[] s_names = new string[6]
        {
            "MyComputer",
            "Intranet",
            "Trusted",
            "Internet",
            "Untrusted",
            "NoZone"
        };

        public SecurityZone SecurityZone
        {
            [SecuritySafeCritical]
            get
            {
                if (m_url != null)
                {
                    m_zone = _CreateFromUrl(m_url);
                }
                return m_zone;
            }
        }

        public Zone(SecurityZone zone)
        {
            if (zone < SecurityZone.NoZone || zone > SecurityZone.Untrusted)
            {
                throw new ArgumentException(Environment.GetResourceString("Argument_IllegalZone"));
            }
            m_zone = zone;
        }

        private Zone(Zone zone)
        {
            m_url = zone.m_url;
            m_zone = zone.m_zone;
        }

        private Zone(string url)
        {
            m_url = url;
            m_zone = SecurityZone.NoZone;
        }

        public static Zone CreateFromUrl(string url)
        {
            if (url == null)
            {
                throw new ArgumentNullException("url");
            }
            return new Zone(url);
        }

        [DllImport("QCall", CharSet = CharSet.Unicode)]
        [SecurityCritical]
        [SuppressUnmanagedCodeSecurity]
        private static extern SecurityZone _CreateFromUrl(string url);

        public IPermission CreateIdentityPermission(Evidence evidence)
        {
            return new ZoneIdentityPermission(SecurityZone);
        }

        public override bool Equals(object o)
        {
            Zone zone = o as Zone;
            if (zone == null)
            {
                return false;
            }
            return SecurityZone == zone.SecurityZone;
        }

        public override int GetHashCode()
        {
            return (int)SecurityZone;
        }

        public override EvidenceBase Clone()
        {
            return new Zone(this);
        }

        public object Copy()
        {
            return Clone();
        }

        internal SecurityElement ToXml()
        {
            SecurityElement securityElement = new SecurityElement("System.Security.Policy.Zone");
            securityElement.AddAttribute("version", "1");
            if (SecurityZone != SecurityZone.NoZone)
            {
                securityElement.AddChild(new SecurityElement("Zone", s_names[(int)SecurityZone]));
            }
            else
            {
                securityElement.AddChild(new SecurityElement("Zone", s_names[s_names.Length - 1]));
            }
            return securityElement;
        }

        public override string ToString()
        {
            return ToXml().ToString();
        }

        internal object Normalize()
        {
            return s_names[(int)SecurityZone];
        }
    }
}