取得拨号上网时动态分配IP的两种方法

取得拨号上网时动态分配IP的两种方法

1:使用socket函数。

在拨号前先取得所有本地IP，记录到字符串列表里。

拨号成功后再遍历一次所有本地IP,和已经记录在字符串列表里IP比较。新增加的IP地址就是拨号上网时动态分配IP了。

2:使用和RAS有关API。

在vc里可以方便使用和ras相关的API。但在C++Builder 6里会出现由版本不同引起的错误。

所以在BCB里关键是要自己指定函数的大小。

以下代码在win2000 + C++Builder 6 环境下编译通过。

在Form里添加2个Edit,3个Button;

//---------------------------------------------------------------------------

#ifndef Unit1H

#define Unit1H

//--------------------------------------------------------------------------- #include

#include

#include

#include

//--------------------------------------------------------------------------- class TForm1 : public TForm

{

__published: // IDE-managed Components

TEdit *Edit1;

TButton *Button1;

TButton *Button2;

TEdit *Edit2;

TButton *Button3;

void __fastcall Button1Click(TObject *Sender);

void __fastcall Button2Click(TObject *Sender);

void __fastcall Button3Click(TObject *Sender);

private: // User declarations

TStringList *m_slIp;

public: // User declarations

__fastcall TForm1(TComponent* Owner);

};

//--------------------------------------------------------------------------- extern PACKAGE TForm1 *Form1;

//--------------------------------------------------------------------------- #endif

//---------------------------------------------------------------------------

#include

#pragma hdrstop

#include "Unit1.h"

#include

#include

//--------------------------------------------------------------------------- #pragma package(smart_init)

#pragma resource "*.dfm"

TForm1 *Form1;

//--------------------------------------------------------------------------- __fastcall TForm1::TForm1(TComponent* Owner)

: TForm(Owner)

{

m_slIp = new TStringList();

}

//---------------------------------------------------------------------------

void __fastcall TForm1::Button1Click(TObject *Sender)

{

WORD wVersionRequested;

WSADATA wsaData;

char cHostName[64] = {0};

HOSTENT *pHost = NULL;

AnsiString psIp;

int Index;

wVersionRequested = MAKEWORD(2, 0);

if(0 != WSAStartup(wVersionRequested, &wsaData))

{

WSACleanup();

ShowMessage("socket版本号不对");

}

if(0 == gethostname(cHostName, 64))

{

pHost = gethostbyname(cHostName);

if(pHost != NULL)

{

for(int i=0; pHost->h_addr_list[i]!=NULL; i++)

{

IN_ADDR *p = (IN_ADDR *)(pHost->h_addr_list[i]);

psIp = inet_ntoa(*p);

m_slIp->Add(psIp); //IP地址存入字符串列表

}

}

else

{

WSACleanup();

ShowMessage("取IP地址失败");

}

}

else

{

ShowMessage("取机器名失败");

}

WSACleanup();

}

//--------------------------------------------------------------------------- void __fastcall TForm1::Button2Click(TObject *Sender)

{

RASCONN RASconn; //活动连接

DWORD BuffSize ; //活动连接所占内存大小；

DWORD ConnNum; //活动连接数目

RASconn.dwSize=692; //必须指定一个连接的内存大小；

BuffSize=692;

RASPPPIP rip;

AnsiString ModemIp;

ZeroMemory(&rip, sizeof(rip));

DWORD size;

size = 40;

rip.dwSize = 40;

DWORD dwReturn=RasEnumConnections(&RASconn,&BuffSize,&ConnNum);

if(dwReturn==0)

{

if(ConnNum>0)

{

//ShowMessage("没有拨号连接！");

if ( (RasGetProjectionInfo(RASconn.hrasconn,RASP_PppIp,

&rip, &size ) ) != 0 )

{

ShowMessage("取IP地址失败");

}

else

{

Edit2->Text = rip.szIpAddress ;

}

}

else

{

ShowMessage("没有拨号连接！");

}

}

else

ShowMessage("RasEnumConnections函数失败！");

}

//--------------------------------------------------------------------------- void __fastcall TForm1::Button3Click(TObject *Sender)

{

WORD wVersionRequested;

WSADATA wsaData;

char cHostName[64] = {0};

HOSTENT *pHost = NULL;

AnsiString psIp;

int Index;

wVersionRequested = MAKEWORD(2, 0);

if(0 != WSAStartup(wVersionRequested, &wsaData))

{

WSACleanup();

ShowMessage("socket版本号不对");

}

if(0 == gethostname(cHostName, 64))

{

pHost = gethostbyname(cHostName);

if(pHost != NULL)

{

for(int i=0; pHost->h_addr_list[i]!=NULL; i++)

{

IN_ADDR *p = (IN_ADDR *)(pHost->h_addr_list[i]);

psIp = inet_ntoa(*p);

if(m_slIp->IndexOf(psIp) < 0)

{

Edit1->Text = psIp;

}

}

}

else

{

WSACleanup();

ShowMessage("取IP地址失败");

}

}

else

{

ShowMessage("取机器名失败");

}

WSACleanup();

delete m_slIp;

}

//---------------------------------------------------------------------------

先在上网前单击Button1，

上网后再单击Butto3得到就是拨号IP.