C#访问远程主机资源的方法

最近要实现访问远程主机的共享目录中的一个文件。遇到了权限问题。google了一下，找到了几种解决方法，记录如下：

一、调用Net use命令

// 使用方法：

//if (Connect("192.168.1.48", "用户名", "密码"))

//{

// File.Copy(@"//192.168.1.48/共享目录/test.txt",
@"e://test.txt", true);

//}

public bool Connect(string remoteHost, string userName, string
passWord)

{

bool Flag = true;

Process proc = new Process();

proc.StartInfo.FileName = "cmd.exe";

proc.StartInfo.UseShellExecute = false;

proc.StartInfo.RedirectStandardInput = true;

proc.StartInfo.RedirectStandardOutput = true;

proc.StartInfo.RedirectStandardError = true;

proc.StartInfo.CreateNoWindow = true;

try

{

proc.Start();

string command = @"net
use //" + remoteHost + " " + passWord + " " + " /user:" + userName +
">NUL";

proc.StandardInput.WriteLine(command);

command = "exit";

proc.StandardInput.WriteLine(command);

while (proc.HasExited == false)

{

proc.WaitForExit(1000);

}

string errormsg = proc.StandardError.ReadToEnd();

if (errormsg != "")

Flag = false;

proc.StandardError.Close();

}

catch (Exception ex)

{

Flag = false;

}

finally

{

proc.Close();

proc.Dispose();

}

return Flag;

}

二、调用WNetAddConnection2、
WNetAddConnection3或者NetUseAdd函数，进行磁盘映射。

using System;

using System.Collections.Generic;

using System.Text;

using System.Runtime.InteropServices;

namespace
WindowsApplication1

{

public class MyMap

{

[DllImport("mpr.dll", EntryPoint = "WNetAddConnection2")]

public static extern uint WNetAddConnection2(

[In] NETRESOURCE lpNetResource,

string lpPassword,

string lpUsername,

uint dwFlags);

[DllImport("Mpr.dll")]

public static extern uint WNetCancelConnection2(

string lpName,

uint dwFlags,

bool fForce);

[StructLayout(LayoutKind.Sequential)]

public class NETRESOURCE

{

public int dwScope;

public int dwType;

public int dwDisplayType;

public int dwUsage;

public string LocalName;

public string RemoteName;

public string Comment;

public string Provider;

}

// remoteNetworkPath format:
@"//192.168.1.48/sharefolder"

// localDriveName format: @"E:"

public static bool CreateMap(string userName, string
password, string remoteNetworkPath, string localDriveName)

{

NETRESOURCE myNetResource = new NETRESOURCE();

myNetResource.dwScope = 2; //2:RESOURCE_GLOBALNET

myNetResource.dwType = 1; //1:RESOURCETYPE_ANY

myNetResource.dwDisplayType = 3;
//3:RESOURCEDISPLAYTYPE_GENERIC

myNetResource.dwUsage = 1; //1:
RESOURCEUSAGE_CONNECTABLE

myNetResource.LocalName = localDriveName;

myNetResource.RemoteName = remoteNetworkPath;

myNetResource.Provider = null;

uint nret = WNetAddConnection2(myNetResource, password, userName, 0);

if (nret == 0)

return true;

else

return false;

}

// localDriveName format: @"E:"

public static bool DeleteMap(string localDriveName)

{

uint nret = WNetCancelConnection2(localDriveName, 1, true);

if (nret == 0)

return true;

else

return false;

}

public void test()

{

// 注意：

// remote、local、username的格式一定要正确，否则可能出现错误

string remote = @"//192.168.1.48/generals";

string local = @"P:";

string username = @"Domain/UserName";

string password = @"Password";

bool ret = MyMap.CreateMap(username, password,
remote, local);

if (ret)

{

//do what you want:

// ...

//File.Copy("q://test.htm", "c://test.htm");

MyMap.DeleteMap(local);

}

}

}

}

三、使用WebClient类

由于WebClient类可以上传下载文件，并且支持以http:、https:和file:开头的URI，所以可以用WebClient类来传输文件。

添加System.Net命名空间后使用如下代码下载文件：

private void Test1()

{

try

{

WebClient client = new WebClient();

NetworkCredential cred = new
NetworkCredential("username", "password", "172.16.0.222
");

client.Credentials = cred;

client.DownloadFile("file://172.16.0.222/test/111.txt",
"111.txt");

}

catch (Exception ex)

{

// 如果网络很慢，而文件又很大，这时可能有超时异常（Time out）。

}

}

public void Test2()

{

try

{

WebClient client = new WebClient();

NetworkCredential cred = new
NetworkCredential("username", "password", "domain
");

client.Credentials = cred;

client.DownloadFile("file://172.16.0.222/test/111.txt",
"111.txt");

}

catch (Exception ex)

{

// 如果网络很慢，而文件又很大，这时可能有超时异常（Time out）。

}

}

类似的还可以试试WebRequest、FileWebRequest等
：

WebRequest req =
WebRequest.Create("file://138.12.12.14/generals/test.htm");

NetworkCredential cred = new
NetworkCredential("username", "password", "IP");

req.Credentials = cred;

WebResponse response = req.GetResponse();

Stream strm = response.GetResponseStream();

StreamReader r = new StreamReader(strm);

... ...

四、角色模拟

using System;

using System.Collections.Generic;

using System.Text;

using System.Runtime.InteropServices;

using System.Security.Principal;

using System.IO;

namespace Test

{

public class Test

{

// logon types

const int LOGON32_LOGON_INTERACTIVE = 2;

const int LOGON32_LOGON_NETWORK = 3;

const int LOGON32_LOGON_NEW_CREDENTIALS = 9;

// logon providers

const int LOGON32_PROVIDER_DEFAULT = 0;

const int LOGON32_PROVIDER_WINNT50 = 3;

const int LOGON32_PROVIDER_WINNT40 = 2;

const int LOGON32_PROVIDER_WINNT35 = 1;

[DllImport("advapi32.dll", CharSet =
CharSet.Auto, SetLastError = true)]

public static extern int LogonUser(String lpszUserName,

String lpszDomain,

String lpszPassword,

int dwLogonType,

int dwLogonProvider,

ref IntPtr phToken);

[DllImport("advapi32.dll", CharSet =
CharSet.Auto, SetLastError = true)]

public static extern int DuplicateToken(IntPtr hToken,

int impersonationLevel,

ref IntPtr hNewToken);

[DllImport("advapi32.dll", CharSet =
CharSet.Auto, SetLastError = true)]

public static extern bool RevertToSelf();

[DllImport("kernel32.dll", CharSet =
CharSet.Auto)]

public static extern bool CloseHandle(IntPtr handle);

private WindowsImpersonationContext
impersonationContext;

public bool impersonateValidUser(String userName,
String domain, String password)

{

WindowsIdentity tempWindowsIdentity;

IntPtr token = IntPtr.Zero;

IntPtr tokenDuplicate = IntPtr.Zero;

if (RevertToSelf())

{

//
这里使用LOGON32_LOGON_NEW_CREDENTIALS来访问远程资源。

// 如果要（通过模拟用户获得权限）实现服务器程序，访问本地授权数据库可

// 以用LOGON32_LOGON_INTERACTIVE

if (LogonUser(userName, domain, password, LOGON32_LOGON_NEW_CREDENTIALS
,

LOGON32_PROVIDER_DEFAULT, ref token) != 0)

{

if (DuplicateToken(token, 2, ref tokenDuplicate) !=
0)

{

tempWindowsIdentity = new
WindowsIdentity(tokenDuplicate);

impersonationContext =
tempWindowsIdentity.Impersonate();

if (impersonationContext != null)

{

System.AppDomain.CurrentDomain.SetPrincipalPolicy(PrincipalPolicy.WindowsPrincipal);

IPrincipal pr =
System.Threading.Thread.CurrentPrincipal;

IIdentity id = pr.Identity;

CloseHandle(token);

CloseHandle(tokenDuplicate);

return true;

}

}

}

}

if (token != IntPtr.Zero)

CloseHandle(token);

if (tokenDuplicate != IntPtr.Zero)

CloseHandle(tokenDuplicate);

return false;

}

public void undoImpersonation()

{

impersonationContext.Undo();

}

public void TestFunc()

{

bool isImpersonated = false;

try

{

if (impersonateValidUser("UserName", "Domain", "Password"
))

{

isImpersonated = true;

//do what you want now, as the special user

// ...

File.Copy(@"//192.168.1.48/generals/now.htm",
"c://now.htm", true);

}

}

finally

{

if (isImpersonated)

undoImpersonation();

}

}

}

}

五、比较

方法一通过调用Shell命令Net Use实现，有点笨拙。

方法二和方法一有些相似之处。映射远程资源，然后访问。

方法三由于会有超时异常出现，所以在网络速度快、传输小文件时是可以的。

方法四通过身份模拟实现远程资源访问。一些服务器进程就是通过这种方式运行的。这种方法也是我的最爱。

六、要注意的地方

关于这几种方法，google后都可以找到一些文章。但是等到自己实际测试时，有时会出现各种小错误，

这些错误基本来源于两方面：

1、函数的参数选择有问题，和自己的环境不相符。

比如

public static extern int LogonUser(String lpszUserName,

String lpszDomain,

String lpszPassword,

int dwLogonType,

int dwLogonProvider,

ref IntPtr phToken);

中的dwLogonType，要访问远程资源就要用LOGON32_LOGON_NEW_CREDENTIALS，

要模拟本机用户就要用LOGON32_LOGON_INTERACTIVE
。

2、函数的参数格式有问题。

a、比如

public static extern int LogonUser(String lpszUserName,

String lpszDomain,

String lpszPassword,

int dwLogonType,

int dwLogonProvider,

ref IntPtr phToken);

中的lpszUserName、lpszDomain、lpszPassword就要写清楚。

我就在这遇到过问题，第一次测试时，远程服务器就是一台独立的文件服务器，这是我的调用方式：

LogonUser("myname", "192.168.1.48", "password",
LOGON32_LOGON_NEW_CREDENTIALS,

LOGON32_PROVIDER_DEFAULT, ref token);

第二次测试时，远程服务器是域MyDomain中的一个成员服务器，提供文件服务。这时代码就应该是：

LogonUser("myname", "MyDomain", "password",
LOGON32_LOGON_NEW_CREDENTIALS,

LOGON32_PROVIDER_DEFAULT, ref token);

注意，代码中是MyDomain而不是IP地址。

b、再如：

参考上面代码

string remote = @"//192.168.1.48/generals";

string local = @"P:";

string username = @"Domain/UserName";

string password = @"Password";

如果@"//192.168.1.48/generals"变成@"//192.168.1.48/generals/”就会出错；

如果是域中的用户，那么把@"Domain/UserName"变成@"UserName"就会出错。