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{$R *.DFM}
function CheckSum(Var Buffer; Size : integer) : Word;
type
TWordArray = Array[0..1] of Word;
var
ChkSum : LongWord;
i : Integer;
begin
ChkSum := 0;
i := 0;
While Size > 1 do begin
ChkSum := ChkSum + TWordArray(Buffer);
inc(i);
Size := Size - SizeOf(Word);
end;
if Size=1 then ChkSum := ChkSum + Byte(TWordArray(Buffer));
ChkSum := (ChkSum shr 16) + (ChkSum and $FFFF);
ChkSum := ChkSum + (Chksum shr 16);
Result := Word(ChkSum);
end;
procedure BuildHeaders(
FromIP : String;
iFromPort : Word;
ToIP : String;
iToPort : Word;
StrMessage : String;
Var Buf : TPacketBuffer;
Var remote : TSockAddr;
Var iTotalSize : Word
);
Var
dwFromIP : LongWord;
dwToIP : LongWord;
iIPVersion : Word;
iIPSize : Word;
ipHdr : T_IP_Header;
udpHdr : T_UDP_Header;
iUdpSize : Word;
iUdpChecksumSize : Word;
cksum : Word;
Ptr : ^Byte;
procedure IncPtr(Value : Integer);
begin
ptr := pointer(integer(ptr) + Value);
end;
begin
// Convert ip address'ss
dwFromIP := inet_Addr(PChar(FromIP));
dwToIP := inet_Addr(PChar(ToIP));
// 初始化 IP 头
//
iTotalSize := sizeof(ipHdr) + sizeof(udpHdr) + length(strMessage);
iIPVersion := 4;
iIPSize := sizeof(ipHdr) div sizeof(LongWord);
ipHdr.ip_verlen := (iIPVersion shl 4) or iIPSize;
ipHdr.ip_tos := 0; // IP type of service
ipHdr.ip_totallength := htons(iTotalSize); // Total packet len
ipHdr.ip_id := 0; // Unique identifier: set to 0
ipHdr.ip_offset := 0; // Fragment offset field
ipHdr.ip_ttl := 128; // Time to live
ipHdr.ip_protocol := $11; // Protocol(UDP)
ipHdr.ip_checksum := 0 ; // IP checksum
ipHdr.ip_srcaddr := dwFromIP; // Source address
ipHdr.ip_destaddr := dwToIP; // Destination address
//
// 初始化 UDP 头
//
iUdpSize := sizeof(udpHdr) + length(strMessage);
udpHdr.src_portno := htons(iFromPort) ;
udpHdr.dst_portno := htons(iToPort) ;
udpHdr.udp_length := htons(iUdpSize) ;
udpHdr.udp_checksum := 0 ;
iUdpChecksumSize := 0;
ptr := @buf[0];
FillChar(Buf, SizeOf(Buf), 0);
Move(ipHdr.ip_srcaddr, ptr^, SizeOf(ipHdr.ip_srcaddr));
IncPtr(SizeOf(ipHdr.ip_srcaddr));
iUdpChecksumSize := iUdpChecksumSize + sizeof(ipHdr.ip_srcaddr);
Move(ipHdr.ip_destaddr, ptr^, SizeOf(ipHdr.ip_destaddr));
IncPtr(SizeOf(ipHdr.ip_destaddr));
iUdpChecksumSize := iUdpChecksumSize + sizeof(ipHdr.ip_destaddr);
IncPtr(1);
Inc(iUdpChecksumSize);
Move(ipHdr.ip_protocol, ptr^, sizeof(ipHdr.ip_protocol));
IncPtr(sizeof(ipHdr.ip_protocol));
iUdpChecksumSize := iUdpChecksumSize + sizeof(ipHdr.ip_protocol);
Move(udpHdr.udp_length, ptr^, sizeof(udpHdr.udp_length));
IncPtr(sizeof(udpHdr.udp_length));
iUdpChecksumSize := iUdpChecksumSize + sizeof(udpHdr.udp_length);
move(udpHdr, ptr^, sizeof(udpHdr));
IncPtr(sizeof(udpHdr));
iUdpChecksumSize := iUdpCheckSumSize + sizeof(udpHdr);
Move(StrMessage[1], ptr^, Length(strMessage));
IncPtr(Length(StrMessage));
iUdpChecksumSize := iUdpChecksumSize + length(strMessage);
cksum := checksum(buf, iUdpChecksumSize);
udpHdr.udp_checksum := cksum;
//
// 现在 IP 和 UDP 头OK了，我们可以把它发送出去。
//
FillChar(Buf, SizeOf(Buf), 0);
Ptr := @Buf[0];
Move(ipHdr, ptr^, SizeOf(ipHdr)); IncPtr(SizeOf(ipHdr));
Move(udpHdr, ptr^, SizeOf(udpHdr)); IncPtr(SizeOf(udpHdr));
Move(StrMessage[1], ptr^, length(StrMessage));
remote.sin_family := AF_INET;
remote.sin_port := htons(iToPort);
remote.sin_addr.s_addr := dwToIP;
end;
procedure TForm1.SendIt;
Var
sh : TSocket;
bOpt : Integer;
ret : Integer;
Buf : TPacketBuffer;
Remote : TSockAddr;
Local : TSockAddr;
iTotalSize : Word;
wsdata : TWSAdata;
begin
// Startup Winsock 2
ret := WSAStartup($0002, wsdata);
if ret< > 0 then begin
memo1.lines.add('WSA Startup failed.');
exit;
end;
with memo1.lines do begin
add('WSA Startup:');
add('Desc.: '+wsData.szDescription);
add('Status: '+wsData.szSystemStatus);
end;
try
// Create socket
sh := Socket(AF_INET, SOCK_RAW, IPPROTO_UDP);
if (sh = INVALID_SOCKET) then begin
memo1.lines.add('Socket() failed: '+IntToStr(WSAGetLastError));
exit;
end;
Memo1.lines.add('Socket Handle = '+IntToStr(sh));
// Option: Header Include
bOpt := 1;
ret := SetSockOpt(sh, IPPROTO_IP, IP_HDRINCL, @bOpt, SizeOf(bOpt));
if ret = SOCKET_ERROR then begin
Memo1.lines.add('setsockopt(IP_HDRINCL) failed: '+IntToStr(WSAGetLastError));
exit;
end;
// Build the packet
BuildHeaders( SrcIP, SrcPrt,
DestIP, DestPort,
'THIS IS A TEST PACKET',
Buf, Remote, iTotalSize );
// Send the packet
ret := SendTo(sh, buf, iTotalSize, 0, Remote, SizeOf(Remote));
if ret = SOCKET_ERROR then
Memo1.Lines.Add('sendto() failed: '+IntToStr(WSAGetLastError))
else
Memo1.Lines.Add('send '+IntToStr(ret)+' bytes.');
// Close socket
CloseSocket(sh);
finally
// Close Winsock 2
WSACleanup;
end;
end;
procedure TForm1.Button1Click(Sender: TObject);
begin
SendIt;
end;
end.
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