mORMot Open Source

bejoy

Member

From: Vladivostok, Russia

Registered: 2019-12-16

Posts: 1

function StringToIPv4

Hello.
It seems that my version of StringToIPv4 conversion should be much faster than existed IPToCardinal.
Moreover, it can operate with standard strings like "192.168.1.2" and strings with extra whitespaces like "192.168.  1.  2";

function StrToIPv4( const AValue: AnsiString; var IPv4: UInt32 ): Boolean; inline;
var
  O, I, C, V: Byte;
  Data: array[0..3] of Byte absolute IPv4;
begin
  // * Inital result
  Result := False;

  // * Reset main iterator
  I := 0;
  // * Walk IPv4 octets
  for O := 3 downto 0 do
  begin
    // * Octet value
    V := 0;
    // * Octet loop
    while True do
    begin
      // * Increase character iterator
      Inc( I );
      // * Get character
      C := Byte( AValue[I] );

      // * If NULL or dot [.]
      if ( C = 0 ) or ( C = 46 ) then Break;
      // * If space [ ]
      if ( C = 32 ) then Continue;

      // * If digit
      if ( C >= 48 ) and ( C <= 57 ) then
        // * Calculate octet value
        V := V * 10 + ( C - 48 )
      else
        // * Exit function
        Exit;

    end;
    // * Write octet value
    Data[O] := V;
  end;

  // * Assign result
  Result := True;
end;

So what do you think about?
P.S. This is my code, so it can be used freely.

ab

Administrator

From: France

Registered: 2010-06-21

Posts: 14,263

Website

Re: function StringToIPv4

Thanks for the input!

I am not sure that it will be much faster than the existing IPToCardinal().
And our version seems safer, since it makes more checks than yours.
For instance, it will ensure that the values are really bytes: yours will parse with no problem an invalid '300.300.300.300' text and return (I guess) something rounded like 44.44.44.44 as resulting IP.
Some error checks are also lacking: I guess '1.2' will be found out as correct, and read out of the input string memory.

In fact, IPToCardinal() is not used much in the framework (only when some IPs are registered to TIPBan), so we don't need replace it.