System.Net.EndpointPermission.Intersect C# (CSharp) Method

        internal EndpointPermission Intersect(EndpointPermission E) {

            String commonName=null;
            TransportType commonTransport;
            int commonPort;

            //
            // Look at the transport
            //

            if (transport == E.transport) {           // same transport
                commonTransport = transport;
            }
            // NO: check if one of the permissions authorize all transports
            else if (transport == TransportType.All) {
                commonTransport = E.transport;
            }
            else if (E.transport == TransportType.All) {
                commonTransport = transport;
            }
            else {   // transport dont match-- intersection is empty
                return null;
            }

            //
            // Determine common port
            //

            if (port == E.port) {
                commonPort = port;
            }
            else if (port == SocketPermission.AllPorts) {
                commonPort = E.port;
            }
            else if (E.port == SocketPermission.AllPorts) {
                commonPort = port;
            }
            else {
                return null;
            }

            //Work out common hostname part
            //
            // This is a fix for INADDR_ANY in Bind()
            // if this.Hostname == "0.0.0.0" then it matches only to e.Hostname="*.*.*.*"
            //
            // The reason is to not pass "0.0.0.0" into Resolve()
            if(this.Hostname.Equals("0.0.0.0"))
            {
                if(E.Hostname.Equals("*.*.*.*") || E.Hostname.Equals("0.0.0.0"))
                    commonName = this.Hostname;//i.e. 0.0.0.0
                else
                    return null;
            }
            else if(E.Hostname.Equals("0.0.0.0"))
            {
                if(this.Hostname.Equals("*.*.*.*") || this.Hostname.Equals("0.0.0.0"))
                    commonName = E.Hostname; //i.e. 0.0.0.0
                else
                    return null;
            }
            else if (IsDns && E.IsDns) {
                //
                // If both are DNS names we compare names as strings
                //
                if(String.Compare(hostname, E.hostname, StringComparison.OrdinalIgnoreCase ) != 0) {
                    return null;
                }
                else {
                    commonName = hostname;
                }
            }
            else
            {
                Resolve();
                E.Resolve();

                //

                if (((address == null) && !wildcard) || ((E.address == null) && !E.wildcard)) {
                    return null;
                }


                //
                // Find intersection of address lists
                if(wildcard && E.wildcard) {
                    string [] wcPieces = hostname.Split(DotSeparator);
                    string [] strPieces = E.hostname.Split(DotSeparator);
                    string  result="";

                    if ((strPieces.Length != 4) || (wcPieces.Length != 4)) {
                        return null;
                    }
                    for (int i = 0; i < 4; i++) {
                        if(i != 0) {
                            result+=".";
                        }
                        if (strPieces[i] == wcPieces[i]) {
                            result+=strPieces[i];
                        }
                        else
                        if (strPieces[i] == "*") {
                            result+=wcPieces[i];
                        }
                        else
                        if (wcPieces[i] == "*") {
                            result+=strPieces[i];
                        }
                        else
                            return null;
                    }
                    commonName = result;
                }else
                if (wildcard) {                                                 //if ME is a wildcard
                    //
                    //
                    // Check for wildcard IP matching
                    //
                    for (int i = 0; i < E.address.Length; ++i) {
                        if (MatchWildcard(E.address[i].ToString())) {
                            commonName = E.hostname;    //SHE fits into my wildcard
                            break;
                        }
                    }
                }
                else if (E.wildcard) {                                   //if SHE is a wildcard
                    for (int i = 0; i < address.Length; ++i) {
                        if (E.MatchWildcard(address[i].ToString())) {
                            commonName = hostname;      //ME fit  into her wildcard
                            break;
                        }
                    }
                }
                else
                {
                    //
                    // Not wildcard: check aginst  IP addresses list
                    //

                    if (address == E.address) {                 // they both are NOT null (already checked)
                        commonName = hostname;
                    }

                    //
                    // Search the IP addresses for match
                    //
                    for (int i = 0; commonName == null && i < address.Length; i++) {
                        for (int k = 0; k < E.address.Length; k++) {
                            if (address[i].Equals(E.address[k])) {
                                commonName = hostname;
                                break;
                            }
                        }
                    }
                }
                if(commonName == null) {
                    return null;
                }
            }

            return new EndpointPermission(commonName, commonPort, commonTransport);
        }
/*

 private void Intersect(ArrayList list1, ArrayList list2, ArrayList result)
 {
     foreach (EndpointPermission perm1 in list1)
     {
         foreach (EndpointPermission perm2 in list2)
         {
             EndpointPermission perm = perm1.Intersect(perm2);
             if (perm != null)
             {
                 // instead of the below it's also okay to simply do:
                 //     result.Add (perm);
                 // below is only done to avoid double entries
                 bool replaced = false;
                 for (int i = 0; i < result.Count; i++)
                 {
                     EndpointPermission res     = (EndpointPermission)result [i];
                     EndpointPermission resperm = perm.Intersect(res);
                     if (resperm != null)
                     {
                         result [i] = resperm;
                         replaced   = true;
                         break;
                     }
                 }
                 if (!replaced)
                 {
                     result.Add(perm);
                 }
             }
         }
     }
 }