Ad:

Pascal and Delphi Discussion Thread
Unsolved
Views: 4004

Page 1
2
Next

You are currently viewing page 1 of this multi-page discussion thread

May 15th, 2008

Hard C++ to Delphi Conversion

Expand Post »

I am working on porting C++ code to Delphi and I am only having a problem with the correct conversion of memmove() statements in the C++ code.

If you or any one you know could help me to convert this C++ code to Delphi I would be thankful.

// Move TCP packet body by sizeof(VPNSEC_HEADER) bytes
memmove(((unsigned char*)pTcpHdr) + sizeof (VPNSEC_HEADER), pTcpHdr, PacketBuffer.m_Length - (sizeof(ether_header) + sizeof(DWORD)*pIpHeader->ip_hl));

// Initialize the injected header
pVpnHdr = (PVPNSEC_HEADER)pTcpHdr;
pVpnHdr->m_Length = (unsigned short)(PacketBuffer.m_Length - (sizeof(ether_header) + sizeof(DWORD)*pIpHeader->ip_hl));
memcpy (pVpnHdr->m_Key, EncKey, 8);

// Calculate padding
padding = 8 - (pVpnHdr->m_Length%8);

// Zero initialize padding
memset (((unsigned char*)(pVpnHdr + 1)) + pVpnHdr->m_Length, 0, padding);

Ray

rayman341

Reputation Points: 10

Solved Threads: 0

Newbie Poster

Offline

8 posts
since May 2008

Permalink

May 15th, 2008

Re: Hard C++ to Delphi Conversion

I think that you can use this procedures (bellow) from System unit:
memmove or memcpy: procedure Move(const Source; var Dest; Count: Integer);

memset: procedure FillChar(var X; Count: Integer; value: Byte);

Bye

Micheus

Reputation Points: 10

Solved Threads: 4

Junior Poster in Training

Offline

72 posts
since Jun 2006

Permalink

May 15th, 2008

Re: Hard C++ to Delphi Conversion

Thank you, but how do I handle the offset:

memmove(((unsigned char*)pTcpHdr) + sizeof (VPNSEC_HEADER), pTcpHdr, PacketBuffer.m_Length - (sizeof(ether_header) + sizeof(DWORD)*pIpHeader->ip_hl));

Ray

rayman341

Reputation Points: 10

Solved Threads: 0

Newbie Poster

Offline

8 posts
since May 2008

Permalink

May 15th, 2008

Re: Hard C++ to Delphi Conversion

I'm not sure about Delphi I, but maybe you can do something like this:

delphi Syntax (Toggle Plain Text)
var
  PtrSource :^Byte;
begin
  PtrSource := pTcpHdr;
  Inc(PtrSource, sizeof (VPNSEC_HEADER));
  Move(pTcpHdr^, PtrSource^, PacketBuffer.m_Length - (sizeof(ether_header) + sizeof(DWORD)*pIpHeader^.ip_hl))
end;
var
  PtrSource :^Byte;
begin
  PtrSource := pTcpHdr;
  Inc(PtrSource, sizeof (VPNSEC_HEADER));
  Move(pTcpHdr^, PtrSource^, PacketBuffer.m_Length - (sizeof(ether_header) + sizeof(DWORD)*pIpHeader^.ip_hl))
end;

notice that parameters positions change between the two compilers:
void * memmove ( void * destination, const void * source, size_t num );
procedure Move(const Source; var Dest; Count: Integer);

You must try.

Micheus

Reputation Points: 10

Solved Threads: 4

Junior Poster in Training

Offline

72 posts
since Jun 2006

Permalink

May 16th, 2008

Re: Hard C++ to Delphi Conversion

//
// Custom VPN information header
//
type
TVPNSecHeaderPtr = ^TVPNSecHeader;
TVPNSecHeader = packed record
h_KeyId: array [1..8] of Byte;
h_Length: Word;
h_IpProto: Byte;
end;

//
// IP header
//
type
TIPHeaderPtr = ^TIPHeader;
TIPHeader = packed record
VerLen: Byte;
TOS: Byte;
TotalLen: Word;
Identifer: Word;
FragOffsets: Word;
TTL: Byte;
Protocol: Byte;
CheckSum: Word;
SourceIp: DWORD;
DestIp: DWORD;
Options: DWORD;
end;

//
// TCP header
//
TTCPHeaderPtr = ^TTCPHeader;
TTCPHeader = packed record
SourcePort:Word;
DestPort:Word;
SequenceNumber

Word;
AcknowledgementNumber

Word;
Offset:Byte; //only left 4 bits. Header length in 32-bit segments
Flags:Byte;
Window:Word;
Checksum:Word; //includes speudo header instead of TCP header.
UrgentPointer:Word;
end;

pIPHeader: TIPHeaderPtr;
pTcpHdr: TTCPHeaderPtr;

Are you sure PtrSource should be a Byte?

rayman341

Reputation Points: 10

Solved Threads: 0

Newbie Poster

Offline

8 posts
since May 2008

Permalink

May 16th, 2008

Re: Hard C++ to Delphi Conversion

Yes, it should be cast to a BytePtr. If you don't then anything you add to it is multiplied by the size of the object's elements.

Delphi Syntax (Toggle Plain Text)
type 
  pPoint = ^tPoint;
  tPoint: record x, y: integer end;
 
function get_point( points: pPoint; index: integer ): tPoint;
  begin
  inc( points, index );  // same as in C (points += index)
  result := points^
  end;
 
function get_point( points: pPoint; index: integer ): tPoint;
  var p: BytePtr;
  begin
  p := pointer( points );
  inc( p, index *sizeof( tPoint ) );
  points := pointer( p );
  result := points^
  end;
type 
  pPoint = ^tPoint;
  tPoint: record x, y: integer end;

function get_point( points: pPoint; index: integer ): tPoint;
  begin
  inc( points, index );  // same as in C (points += index)
  result := points^
  end;

function get_point( points: pPoint; index: integer ): tPoint;
  var p: BytePtr;
  begin
  p := pointer( points );
  inc( p, index *sizeof( tPoint ) );
  points := pointer( p );
  result := points^
  end;

The first version works the same as in C and C++. If the size of the pointer's target is known, it is automatically multiplied into the index:

C++ Syntax (Toggle Plain Text)
int *a;
a[ 5 ] == (a +5)
int *a;
a[ 5 ] == (a +5)

If, however, the offset calculation is in bytes you must first cast it to a byte pointer:

C++ Syntax (Toggle Plain Text)
int *a;
a[ 5 ] == ((unsigned char*)a +(5 *sizeof( a[ 0 ] )))
int *a;
a[ 5 ] == ((unsigned char*)a +(5 *sizeof( a[ 0 ] )))

Hope this helps.

Duoas

Featured Poster

Reputation Points: 1140

Solved Threads: 229

Postaholic

Offline

2,039 posts
since Oct 2007

Permalink

May 16th, 2008

Re: Hard C++ to Delphi Conversion

So what is:
memset (((unsigned char*)(pVpnHdr + 1)) + pVpnHdr->m_Length, 0, padding);

converted to Delphi?

rayman341

Reputation Points: 10

Solved Threads: 0

Newbie Poster

Offline

8 posts
since May 2008

Permalink

May 16th, 2008

Re: Hard C++ to Delphi Conversion

Messy.

Delphi Syntax (Toggle Plain Text)
var
  bp: PByte;
begin
  bp := pVpnHdr;
  inc( bp, sizeof( pVpnHdr ) +pVpnHdr^.m_Length );
  fillchar( bp^, padding, 0 )
end;
var
  bp: PByte;
begin
  bp := pVpnHdr;
  inc( bp, sizeof( pVpnHdr ) +pVpnHdr^.m_Length );
  fillchar( bp^, padding, 0 )
end;

Micheus already gave you the basics of this above.

Last edited by Duoas; May 16th, 2008 at 11:30 am.

Duoas

Featured Poster

Reputation Points: 1140

Solved Threads: 229

Postaholic

Offline

2,039 posts
since Oct 2007

Permalink

May 16th, 2008

Re: Hard C++ to Delphi Conversion

So after the fillchar() do I ref pTcpHdr or bp.

if I understand this correctly pTcpHdr is still used since bp only help change the contants of pTcpHdr.

Ray

rayman341

Reputation Points: 10

Solved Threads: 0

Newbie Poster

Offline

8 posts
since May 2008

Permalink

May 16th, 2008

Re: Hard C++ to Delphi Conversion

Click to Expand / Collapse Quote originally posted by Duoas ...

Yes, it should be cast to a BytePtr. If you don't then anything you add to it is multiplied by the size of the object's elements.

Thank you by this support Duoas. I forgot to explain this.

Click to Expand / Collapse Quote originally posted by rayman341 ...

So after the fillchar() do I ref pTcpHdr or bp.

both is the same thing - pointing to same memory address.

Quote ...

if I understand this correctly pTcpHdr is still used since bp only help change the contants of pTcpHdr.

You must use bp to move across memory allocated to pTcpHdr.
If you change pTcpHdr value, you are losting the start of memory allocated to it and lost its reference for future access.

Bye

Micheus

Reputation Points: 10

Solved Threads: 4

Junior Poster in Training

Offline

72 posts
since Jun 2006

Page 1
2
Next

This thread is more than three months old

No one has posted to this discussion for at least three months. Please let old threads die and do not reply to them unless you feel you have something new and valuable to contribute that absolutely must be added to make the discussion complete. Otherwise, please start a new thread in this forum instead.

Previous Thread in Pascal and Delphi Forum Timeline: more C++ to Delphi

Next Thread in Pascal and Delphi Forum Timeline: System.DateTime to TDateTime

DaniWeb Message

Cancel Changes

User Name
Password