如何编程实现ARP?(100分)

ARP协议，已知对方IP，要得到对方的物理地址。如何编程实现呢？

笨办法
先ping这个ip,然后arp -a 重定向到一个临时文件里，分析这个文件

发ARP包，对方就返回ARP_ANS

如何才能发ARP包？

listen

用Platform SDK的iphelp库函数：SendARP.
可以直接取得对方的物理地址。
我这是MFC的原吗,库文件是 IPHELPAPI.LIB.
BOOL GetMacAdd(LPCTSTR strIP, CString& strMAcAddr)
{
BOOL bRet = FALSE;
unsigned char ulMacAddr[6];
unsigned long ulMacAddrLen = 6;

CString destIP = CString(strIP);
DWORD dwIPAddr = inet_addr(destIP);

DWORD dwret = SendARP(dwIPAddr, 0,(PULONG)ulMacAddr, &ulMacAddrLen);
if(dwret == 0)
{
strMAcAddr.Format("%02X-%02X-%02X-%02X-%02X-%02X", ulMacAddr[0],ulMacAddr[1],ulMacAddr[2],ulMacAddr[3],ulMacAddr[4],ulMacAddr[5]);
return TRUE;
}
return FALSE;
}

to takou:VC中似乎没有IPHELPAPI.LIB，从哪里可以得到？

listen

you can get it from Platform SDK.

to takou:
How can I get Platform SDK ? Is it in the VisualStudio?

no, if you have the entire set of MSDN's CDROM, you can find it.
I 've sent the necessary file to you.

to takou: Thanks a lot!

to takou:
不了解C的结构，请问SendARP各参数的类型，谢谢。hzcbb@21cn.com
SendARP(dwIPAddr, 0,(PULONG)ulMacAddr, &ulMacAddrLen);

please read the sample code.

我试过如下写法，报告errorcode=50，不能发送arp包。
也试过参数4用dword，errorcode=87。

所以想请教一下写法，谢谢

Function sendarp(ipaddr:ulong;
temp:dword;
ulmacaddrointer;
ulmacaddrlengointer) : DWord; StdCall;
implementation

{$R *.DFM}
Function sendarp; External 'Iphlpapi.dll' Name 'SendARP';

procedure TForm1.Button1Click(Sender: TObject);
var
myip:ulong;
mymac:array[0..5] of byte;
mymaclength:ulong;
r:integer;
begin
myip:=inet_addr(PChar('10.0.0.1'));
mymaclength:=length(mymac);
r:=sendarp(myip,0,@mymac,@mymaclength);
label1.caption:='errorcode:'+inttostr(r);
label2.caption:=format('%2.2x:%2.2x:%2.2x:%2.2x:%2.2x:%2.2x',[mymac[0],mymac[1],mymac[2],mymac[3],mymac[4],mymac[5]]);
end;

to cbb:
对于delphi我不熟悉。
有一点要注意：
mymaclength的值如果不是6的话不行。

以下是MSDN的说明。
SendARP
The SendARP function sends an ARP request to obtain the physical address that corresponds to the specified destination IP address.

DWORD SendARP(
IPAddr DestIP, // destination IP address
IPAddr SrcIP, // IP address of sender
PULONG pMacAddr, // returned physical address
PULONG PhyAddrLen // length of returned physical addr.
);
Parameters
DestIP
[in] Specifies the destination IP address. The ARP request attempts to obtain the physical address that corresponds to this IP address.
SrcIP
[in] Specifies the IP address of the sender. This parameter is optional. The caller may specify zero for the parameter.
pMacAddr
[out] Pointer to a ULONG variable. This variable receives the physical address that corresponds to the IP address specified by the DestIP parameter.
PhyAddrLen
[out] Pointer to a ULONG variable. This variable contains the length of the physical address pointed to by the pMacAddr parameter.
Return Values
If the function succeeds, the return value is NO_ERROR.

If the function fails, use FormatMessage to obtain the message string for the returned error.

祝好运。
如果还不对，请zw84611回答你的问题吧。他也许用delphi成功过。

是win98不支持吧？thanks
Requirements
Windows NT/2000 or later: Requires Windows 2000 or later.
Windows 95/98/Me: Unsupported.
Header: Declared in Iphlpapi.h.
Library: Use Iphlpapi.lib.

我的系统是NT Server，为什么也出现errorcode=50？
望各位多多指教！！！！