misc network

miscnetwork

        /// <summary>
        /// Gets the next available open port for use with RTP Video Streams.  Range is evenly numbered UDP ports between 9000 and 9999.
        /// </summary>
        /// <param name="localAddress">The local address.</param>
        /// <returns></returns>
        public static int GetOpenPort(IPAddress localAddress)
        {
            return GetOpenPort(localAddress, 9000, 9999, 2, true, true);
        }


        /// <summary>
        /// Gets the nearest open port (or port + range).
        ///  </summary>
        /// <param name="localAddress">The local address.</param>
        /// <param name="startingPort">The starting port.</param>
        /// <param name="endingPort">The ending port.</param>
        /// <param name="range">The range.</param>
        /// <param name="requireEvenBasePort">if set to <c>true</c> [require even base port].</param>
        /// <param name="udp">if set to <c>true</c> [UDP].</param>
        /// <returns></returns>
        public static int GetOpenPort(IPAddress localAddress, int startingPort, int endingPort, int range, bool requireEvenBasePort, bool udp)
        {
            // This will work fine in most cases, but there is no guarantee that a port obtained here will be open at the time that 
            // you attempt to use it.  This should suffice for our purposes here, but a more robust implementation is advised for production applications.
            // best practice here is to make sure we use the ports obtained through this method before allowing it to be called again.

            ArgHelper.AssertThat(range >= 1);
            ArgHelper.AssertThat(endingPort <= 65535);
            if (requireEvenBasePort)
                ArgHelper.AssertThat(startingPort % 2 == 0);

            var additionalPorts = range - 1;
            var validUsedPorts = new List<int>(
                (
                from endPoint in (udp ? IPGlobalProperties.GetIPGlobalProperties().GetActiveUdpListeners() : IPGlobalProperties.GetIPGlobalProperties().GetActiveTcpListeners()) 
                where ((endPoint.Address == localAddress) && (endPoint.Port >= startingPort) && (endPoint.Port + additionalPorts <= endingPort)) 
                select endPoint.Port
                ));

            if (validUsedPorts.Count == 0)
                return startingPort;

            validUsedPorts.Sort();

            for (var i = startingPort; i <= endingPort - additionalPorts; i++)
            {
                //skip odd base ports if needed.
                if (requireEvenBasePort && i % 2 != 0)
                    continue;

                //skip the rest if the port is in use.
                if (validUsedPorts.Contains(i))
                    continue;

                //return current port if no range was defined.
                if (additionalPorts == 0)
                    return i;
                
                var isUsed = false;
                //test to see if the requested range is available
                for (var j = i + 1; j <= i + additionalPorts; j++)
                {
                    if (!validUsedPorts.Contains(j))
                        continue;

                    isUsed = true;
                    i = j;
                }

                if (isUsed)
                    continue;

                return i;
            }

            return 0; //socket creation with port 0 will find any port available outside our range.
        }

        /// <summary>
        /// Gets the local ip that the system will use for a connection to the specified remote IP Address.
        /// 
        /// Use this to automate RTP Sendback Url definition.
        /// </summary>
        /// <param name="remoteIpAddress">The remote ip address.</param>
        /// <returns></returns>
        public static IPAddress GetLocalIpAddressUsedFor(IPAddress remoteIpAddress)
        {
            using (var udpClient = new UdpClient())
            {
                udpClient.Connect(remoteIpAddress, 1);
                return ((IPEndPoint)udpClient.Client.LocalEndPoint).Address;
            }
        }