Socket API实现Trace Route

Windows自带的Tracert是向远程主机发送ICMP包进行追踪，但是目前很多主机关闭了ICMP答复，这个工具不太好使了~~~~~原理咱知道，正规的Trace不就是发送TTL依次递增的UDP包吗？什么网关和路由敢随意丢弃我们的UDP包而不通知我们？俺的ICMP包你可以不理，但是UDP包~~~~~不怕俺黑你？？？

unit YRecords;

interface

uses
Windows;

const
PACKET_SIZE = 32;
MAX_PACKET_SIZE = 512;
TRACE_PORT = 34567;
LOCAL_PORT = 5555;

type
s32 = Integer;
u32 = DWORD;
u8 = Byte;
u16 = word; PU16 = ^U16;

//
//IP Packet Header
//
PIPHeader = ^YIPHeader;
YIPHeader = record
u8verlen : u8;//4bits ver, 4bits len, len*4=true length
u8tos : u8;//type of service, 3bits 优先权(现在已经被忽略), 4bits TOS, 最多只能有1bit为1
u16totallen : u16;//整个IP数据报的长度，以字节为单位。
u16id : u16;//标识主机发送的每一份数据报。
u16offset : u16;//3bits 标志，13bits片偏移
u8ttl : u8;//生存时间字段设置了数据报可以经过的最多路由器数。
u8protol : u8;//协议类型，6表示传输层是TCP协议。
u16checksum : u16;//首部检验和。
u32srcaddr : u32;//源IP地址，不是‘xxx.xxx.xxx.xxx’的形势哦
u32destaddr : u32;//目的IP地址，同上
end;

//
//ICMP Packet Header
//
PICMPHeader = ^YICMPHeader;
YICMPHeader = record
u8type : u8;
u8code : u8;
u16chksum : u16;
u16id : u16;
u16seq : u16;
end;

unit Unit1;

interface

uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls, YRecords, winsock2;

type
TForm1 = class(TForm)
ListBox1: TListBox;
Edit1: TEdit;
Button1: TButton;
procedure FormCreate(Sender: TObject);
procedure FormClose(Sender: TObject; var Action: TCloseAction);
procedure Button1Click(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
end;

var
Form1: TForm1;

implementation

{$R *.dfm}

function DecodeIcmpReply( pbuf: PChar; var seq: s32 ): string;
var
pIpHdr : PChar;
pIcmphdr : PICMPHeader;
sip : string;
ttl : integer;
begin
pIpHdr := pbuf;
sip := inet_ntoa( TInAddr( PIPHeader(pIpHdr)^.u32srcaddr ) );
ttl := PIPHeader(pIpHdr)^.u8ttl;

Inc( pIpHdr, (PIPHeader(pIpHdr)^.u8verlen and $0F) * 4 );
pIcmpHdr := PICMPHeader(pIpHdr);

result := '''''''';
if pIcmpHdr^.u8type = 3 then //目的不可达信息，Trace完成
seq := 0;
if pIcmpHdr^.u8type = 11 then //超时信息，正在Trace
result := Format( ''''M2s?''', [seq, sip, ttl] );
end;

procedure ErrMsg( msg: string );
begin
MessageBox( 0, PChar(msg), ''''Ping Program Error'''', MB_ICONERROR );
end;

procedure TForm1.FormCreate(Sender: TObject);
var
wsa : TWSAData;
begin
if WSAStartup( $0202, wsa ) <> 0 then
ErrMsg( ''''Windows socket is not responed.'''' );
ListBox1.Font.Name := ''''Courier New'''';
ListBox1.Font.Size := 9;
end;

procedure TForm1.FormClose(Sender: TObject; var Action: TCloseAction);
begin
if WSACleanup <> 0 then
ErrMsg( ''''Windows socket can not be closed.'''' );
end;

procedure TForm1.Button1Click(Sender: TObject);
const
SIO_RCVALL = IOC_IN or IOC_VENDOR or 1;
var
rawsock : TSocket;
pRecvBuf : PChar;
FromAdr : TSockAddr;
FromLen : s32;
fd_read : TFDSet;
timev : TTimeVal;
sReply : string;
udpsock : TSocket;
ret : s32;
DestAdr : TSockAddr;
pSendBuf : PChar;
ttl, opt : s32;
pHost : PHostEnt;
begin
//创建一个RAWSOCK接收回应ICMP包
rawsock := socket( AF_INET, SOCK_RAW, IPPROTO_ICMP );

FromAdr.sin_family := AF_INET;
FromAdr.sin_port := htons(0);
FromAdr.sin_addr.S_addr := inet_addr(''''192.168.1.12''''); //换成你的IP

//如果不bind就无法接收包了~~~因为下面还要创建一个UDPSOCK
bind( rawsock, @FromAdr, SizeOf(FromAdr) );

Opt := 1;
WSAIoctl( rawsock, SIO_RCVALL, @Opt, SizeOf(Opt), nil, 0, @ret, nil, nil );

//接收ICMP回应包的缓冲区
pRecvBuf := AllocMem( MAX_PACKET_SIZE );

//创建一个UDPSOCK发送探测包
udpsock := socket( AF_INET, SOCK_DGRAM, IPPROTO_UDP );

//要发送的UDP数据
pSendBuf := AllocMem( PACKET_SIZE );
FillChar( pSendBuf^, PACKET_SIZE, ''''C'''' );

FillChar( DestAdr, sizeof(DestAdr), 0 );
DestAdr.sin_family := AF_INET;
DestAdr.sin_port := htons( TRACE_PORT );
DestAdr.sin_addr.S_addr := inet_addr( PChar(Edit1.Text) );

//如果edit1.text不是IP地址，则尝试解析域名
if DestAdr.sin_addr.S_addr = INADDR_NONE then

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