.

Summary

Enum all Available Ports in a System.

C# Signature:

DllImport("winspool.drv", EntryPoint="EnumPortsA")]
static extern int EnumPorts (string pName, int Level, IntPtr lpbPorts, int cbBuf,ref int pcbNeeded,ref int pcReturned);

VB Signature:

TODO

User-Defined Types:

None.

Alternative Managed API:

Do you know one? Please contribute it!

Notes:

None.

Tips & Tricks:

Please add some!

Sample Code:

    using System;
    using System.Runtime.InteropServices;

    namespace EnumPorts
    {
        public class PortHelper
        {

            [Flags]
            public enum  PortType:int
            {
                write =0x1,
                read  =0x2,
                redirected = 0x4,
                net_attached=0x8
            }

            [StructLayout(LayoutKind.Sequential)]
            public struct PORT_INFO_2
            {
                public string pPortName;
                public string pMonitorName;
                public string pDescription;
                public PortType fPortType;
                internal int Reserved;
            }

            [DllImport("winspool.drv", EntryPoint="EnumPortsA",SetLastError=true)]
            private static extern int EnumPorts (string pName, int Level, IntPtr lpbPorts, int cbBuf,ref int pcbNeeded,ref int pcReturned);

            public static PORT_INFO_2[] GetAvailablePorts()
            {
                return GetAvailablePorts("");
            }
            public static PORT_INFO_2[] GetAvailablePorts(string servername)
            {
                int ret;
                int pcbNeeded=0;            int pcReturned=0;            int lastErr =0;            IntPtr TempBuff=IntPtr.Zero;
                PORT_INFO_2[] pinfo=null;
                ret=EnumPorts(servername,2,TempBuff,0,ref pcbNeeded,ref pcReturned);

                try
                {

                    TempBuff=Marshal.AllocHGlobal(pcbNeeded+1);

                    ret = EnumPorts(servername, 2, TempBuff, pcbNeeded,ref pcbNeeded,ref pcReturned);
                    lastErr=Marshal.GetLastWin32Error();
                    if (ret!=0)
                    {
                        IntPtr CurrentPort =TempBuff;

                        pinfo=new PORT_INFO_2[pcReturned];

                        for (int i=0;i<pcReturned;i++)
                        {
                            pinfo[i]=(PORT_INFO_2)Marshal.PtrToStructure(CurrentPort,typeof(PORT_INFO_2));                        
                            CurrentPort=(IntPtr)(CurrentPort.ToInt32()+Marshal.SizeOf(typeof(PORT_INFO_2)));
                        }
                        CurrentPort=IntPtr.Zero;
                    }
                    return   pinfo;            
                }
                finally
                {
                    if (TempBuff!=IntPtr.Zero)
                    {
                        Marshal.FreeHGlobal(TempBuff);
                        TempBuff=IntPtr.Zero;
                    }
                }
            }

        }
    }

Documentation

EnumPorts on MSDN