首先,对编程中需要的动态链接库作一简要说明:在Windows的System目录下,你
可以找到Icmp.dll文件,该动态链接库提供了ICMP协议的所有功能,我们的编程就建立
在
对该动态链接库的调用上。
Icmp.dll文件内的调用函数说明如下:
1、IcmpCreateFile
打开一个句柄,通过该句柄你可以发送ICMP的请求回送报文。
2、IcmpCloseHandle
关闭你通过IcmpCreateFile函数打开的句柄。
3、IcmpSendEcho
通过你打开的句柄发送ICMP请求,在超时或应答报文接收后返回。其参数基本上和
它的帧结构一致,可参看下面的程序部分,其具体含意你可以参看有关ICMP协议的书
籍。
初步了解了上述的三个函数后,我们就可以开始编程了。
首先,我们的程序运行后应该有如图1所示的基本功能。为此,我们可先在Delphi的
窗口中放入右上图中所示的控件,如按钮、编辑框和文本显示框等。
(G72.JPG)
例程运行示意图
然后,在程序的开始部分(FormCreate)对WinSocket进行初始化,其作用是申明
使用的版本信息,同时调入Icmp.dll库。
type
PIPOptionInformation = ^TIPOptionInformation;
TIPOptionInformation = packed record
TTL: Byte;
TOS: Byte;
Flags: Byte;
OptionsSize: Byte;
OptionsData: PChar;
end;
PIcmpEchoReply = ^TIcmpEchoReply;
TIcmpEchoReply = packed record
Address: DWORD;
Status: DWORD;
RTT: DWORD;
DataSize: Word;
Reserved: Word;
Data: Pointer;
Options: TIPOptionInformation;
end;
TIcmpCreateFile = function: THandle; stdcall;
TIcmpCloseHandle = function(IcmpHandle: THandle): Boolean;
stdcall;
TIcmpSendEcho = function(IcmpHandle:THandle;
DestinationAddress: DWORD;
RequestData: Pointer;
RequestSize: Word;
RequestOptions: PIPOptionInformation;
ReplyBuffer: Pointer;
ReplySize: DWord;
Timeout: DWord
): DWord; stdcall;
TMyPing = class(TForm)
Panel1: TPanel;
Label1: TLabel;
PingEdit: TEdit;
ExeBtn: TButton;
Button2: TButton;
Button3: TButton;
StatusShow: TMemo;
procedure Button3Click(Sender: TObject);
procedure FormCreate(Sender: TObject);
procedure ExeBtnClick(Sender: TObject);
private
{ Private declarations }
hICMP: THANDLE;
IcmpCreateFile : TIcmpCreateFile;
IcmpCloseHandle: TIcmpCloseHandle;
IcmpSendEcho: TIcmpSendEcho;
public
{ Public declarations }
end;
procedure TMyPing.FormCreate(Sender: TObject);
var
WSAData: TWSAData;
hICMPdll: HMODULE;
begin
?
// Load the icmp.dll stuff
hICMPdll := LoadLibrary('icmp.dll');
@ICMPCreateFile := GetProcAddress(hICMPdll, 'IcmpCreateFile');
@IcmpCloseHandle := GetProcAddress(hICMPdll,
'IcmpCloseHandle');
@IcmpSendEcho := GetProcAddress(hICMPdll, 'IcmpSendEcho');
hICMP := IcmpCreateFile;
StatusShow.Text := '';
StatusShow.Lines.Add('目的IP地址 字节数 返回时间(毫秒)');
end;
接下来,就要进行如下所示的Ping操作的实际编程过程了。
procedure TMyPing.ExeBtnClick(Sender: TObject);
var
IPOpt:TIPOptionInformation;// IP Options for packet to send
FIPAddress
WORD;
pReqData,pRevData
Char;
pIPE
IcmpEchoReply;// ICMP Echo reply buffer
FSize: DWORD;
MyString:string;
FTimeOut
WORD;
BufferSize
WORD;
begin
if PingEdit.Text <> '' then
begin
FIPAddress := inet_addr(PChar(PingEdit.Text));
FSize := 40;
BufferSize := SizeOf(TICMPEchoReply) + FSize;
GetMem(pRevData,FSize);
GetMem(pIPE,BufferSize);
FillChar(pIPE^, SizeOf(pIPE^), 0);
pIPE^.Data := pRevData;
MyString := 'Hello,World';
pReqData := PChar(MyString);
FillChar(IPOpt, Sizeof(IPOpt), 0);
IPOpt.TTL := 64;
FTimeOut := 4000;
IcmpSendEcho(hICMP, FIPAddress, pReqData, Length(MyString),
@IPOpt, pIPE, BufferSize, FTimeOut);
if pReqData^ = pIPE^.Options.OptionsData^ then
begin
StatusShow.Lines.Add(PChar(PingEdit.Text) + ' '
+IntToStr(pIPE^.DataSize) + ' ' +IntToStr(pIPE^.RTT));
end;
FreeMem(pRevData);
FreeMem(pIPE);
end
end;
通过上面的编程,我们就实现了Ping功能的界面操作。实际上,ICMP协议的功能还
有很
多,都可以通过对Icmp.dll的函数调用来实现。