Sort IP addresses in a cross-platform way
lazarus / 38-Networking and Web Programming

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JD · 2014-02-18 12:37

Hi there everyone,

I have a Windows function that sorts IP addresses & I'm trying to make
it cross-platform & I need some help with that. The function is as
shown below. It relies on Winsock so I need the equivalent on other
platforms e.g Linux:

Code: [Select]  { Helper functions }
  function IPSort(AString1, AString2: string): integer;
  // Modified original source:
http:www.delphipages.com/forum/showthread.php?t=104191
  var
    a, b: TInAddr;
  begin
    //
    {$IFDEF MSWINDOWS}
    a.S_addr := inet_addr(PChar(AString1));
    b.S_addr := inet_addr(PChar(AString2));
    //
    if ntohl(a.S_addr) > ntohl(b.S_addr) then
      Result := -1
    else if ntohl(b.S_addr) > ntohl(a.S_addr) then
      Result := 1
    else
      Result := 0;
    {$ELSE}     // this part is untested and fails to compile bcos of
in-addr
    a.S_addr := in_addr(PChar(AInt1));
    b.S_addr := in_addr(PChar(AInt2));
    //
    if ntohl(a.S_addr) > ntohl(b.S_addr) then
      Result := -1
    else if ntohl(b.S_addr) > ntohl(a.S_addr) then
      Result := 1
    else
      Result := 0;
    {$ENDIF}
  end;

I use Code: [Select]{$IFDEF MSWINDOWS}Winsock,{$ELSE}Sockets,{$ENDIF}
in the uses clause.

Thanks,

JD

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marcov · 2014-02-18 12:54

winsock has no *nix equivalent.

But while sockets originates on *nix, it is supported on Windows for
over 8 years. Simply change everything to use sockets.

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JD · 2014-02-18 15:18

Quote from: marcov on February 18, 2014, 01:54:55 pmwinsock has no
*nix equivalent.

But while sockets originates on *nix, it is supported on Windows for
over 8 years. Simply change everything to use sockets.

How do I do that? Thanks.

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engkin · 2014-02-18 16:15

Unit Sockets has ntohl and StrToHostAddr.

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JD · 2014-02-19 08:44

Quote from: engkin on February 18, 2014, 05:15:53 pmUnit Sockets has
ntohl and StrToHostAddr.

So if I understand you, changing in_addr(PChar(AInt1)) to
StrToHostAddr(PChar(AInt1)) ought to do the trick since StrToHostAddr
is a function which returns an in_addr value? That seems to be the
only change necessary.

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Leledumbo · 2014-02-19 10:44

Quote from: JD on February 18, 2014, 04:18:08 pmQuote from: marcov on
February 18, 2014, 01:54:55 pmwinsock has no *nix equivalent.

But while sockets originates on *nix, it is supported on Windows for
over 8 years. Simply change everything to use sockets.

How do I do that? Thanks.
Change:
Code: [Select]{$IFDEF MSWINDOWS}Winsock,{$ELSE}Sockets,{$ENDIF}to:
Code: [Select]Sockets

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JD · 2014-02-20 05:51

Quote from: Leledumbo on February 19, 2014, 11:44:07 amQuote from: JD
on February 18, 2014, 04:18:08 pmQuote from: marcov on February 18,
2014, 01:54:55 pmwinsock has no *nix equivalent.

But while sockets originates on *nix, it is supported on Windows for
over 8 years. Simply change everything to use sockets.

How do I do that? Thanks.
Change:
Code: [Select]{$IFDEF MSWINDOWS}Winsock,{$ELSE}Sockets,{$ENDIF}to:
Code: [Select]Sockets
Ah. I see. Thanks.