C# Wince GPRS拨号类实现与参数结构

using System;
using System.Runtime.InteropServices;

namespace Rainfall.Base.CNetWork
{
    public class CRasDial
    {
        public const int RAS_MaxEntryName = 256;
        public const int RAS_MaxPhoneNumber = 128;
        public const int UNLEN = 256;
        public const int PWLEN = 256;
        public const int DNLEN = 15;
        public const int MAX_PATH = 260;
        public const int RAS_MaxDeviceType = 16;
        public const int RAS_MaxCallbackNumber = RAS_MaxPhoneNumber;

        public delegate void Callback(uint unMsg, int rasconnstate, int dwError);

        [StructLayout(LayoutKind.Sequential, Pack = 4, CharSet = CharSet.Auto)]
        public struct RASDIALPARAMS
        {
            public int dwSize;
            [MarshalAs(UnmanagedType.ByValTStr, SizeConst = RAS_MaxEntryName + 1)]
            public string szEntryName;
            [MarshalAs(UnmanagedType.ByValTStr, SizeConst = RAS_MaxPhoneNumber + 1)]
            public string szPhoneNumber;
            [MarshalAs(UnmanagedType.ByValTStr, SizeConst = RAS_MaxCallbackNumber + 1)]
            public string szCallbackNumber;
            [MarshalAs(UnmanagedType.ByValTStr, SizeConst = UNLEN + 1)]
            public string szUserName;