Identifying subnet mask of the computer in Delphi - delphi

Question

I am looking for a way to be able to retrieve IP Subnet mask of the computer I am currently
running on at run time, in Delphi.
Is there a way in code for me to retrieve the subnet mask and store it so that I may use it in other operations?
Thanks

Answer 1

You can use the Win32_NetworkAdapterConfiguration WMI class and the IPSubnet property.
Try this sample code
{$APPTYPE CONSOLE}
uses
SysUtils,
ActiveX,
ComObj,
Variants;
function VarArrayToStr(const vArray: variant): string;
function _VarToStr(const V: variant): string;
var
Vt: integer;
begin
Vt := VarType(V);
case Vt of
varSmallint,
varInteger : Result := IntToStr(integer(V));
varSingle,
varDouble,
varCurrency : Result := FloatToStr(Double(V));
varDate : Result := VarToStr(V);
varOleStr : Result := WideString(V);
varBoolean : Result := VarToStr(V);
varVariant : Result := VarToStr(Variant(V));
varByte : Result := char(byte(V));
varString : Result := String(V);
varArray : Result := VarArrayToStr(Variant(V));
end;
end;
var
i : integer;
begin
Result := '[';
if (VarType(vArray) and VarArray)=0 then
Result := _VarToStr(vArray)
else
for i := VarArrayLowBound(vArray, 1) to VarArrayHighBound(vArray, 1) do
if i=VarArrayLowBound(vArray, 1) then
Result := Result+_VarToStr(vArray[i])
else
Result := Result+'|'+_VarToStr(vArray[i]);
Result:=Result+']';
end;
procedure GetWin32_NetworkAdapterConfigurationInfo;
const
WbemUser ='';
WbemPassword ='';
WbemComputer ='localhost';
wbemFlagForwardOnly = $00000020;
var
FSWbemLocator : OLEVariant;
FWMIService : OLEVariant;
FWbemObjectSet: OLEVariant;
FWbemObject : OLEVariant;
oEnum : IEnumvariant;
iValue : LongWord;
begin;
FSWbemLocator := CreateOleObject('WbemScripting.SWbemLocator');
FWMIService := FSWbemLocator.ConnectServer(WbemComputer, 'root\CIMV2', WbemUser, WbemPassword);
FWbemObjectSet:= FWMIService.ExecQuery('SELECT * FROM Win32_NetworkAdapterConfiguration Where IpEnabled=True','WQL',wbemFlagForwardOnly);
oEnum := IUnknown(FWbemObjectSet._NewEnum) as IEnumVariant;
while oEnum.Next(1, FWbemObject, iValue) = 0 do
begin
Writeln(Format('Caption %s',[String(FWbemObject.Caption)]));// String
if not VarIsNull(FWbemObject.DHCPServer) then
Writeln(Format('DHCPServer %s',[String(FWbemObject.DHCPServer)]));// String
if not VarIsNull(FWbemObject.IPAddress) then
Writeln(Format('IPAddress %s',[VarArrayToStr(FWbemObject.IPAddress)]));// array String
if not VarIsNull(FWbemObject.IPSubnet) then
Writeln(Format('IPSubnet %s',[VarArrayToStr(FWbemObject.IPSubnet)]));// array String
if not VarIsNull(FWbemObject.MACAddress) then
Writeln(Format('MACAddress %s',[VarArrayToStr(FWbemObject.MACAddress)]));// array String
Writeln;
FWbemObject:=Unassigned;
end;
end;
begin
try
CoInitialize(nil);
try
GetWin32_NetworkAdapterConfigurationInfo;
finally
CoUninitialize;
end;
except
on E:EOleException do
Writeln(Format('EOleException %s %x', [E.Message,E.ErrorCode]));
on E:Exception do
Writeln(E.Classname, ':', E.Message);
end;
Writeln('Press Enter to exit');
Readln;
end.

Answer 2

1) computer may be opart of different Nets/Subnets. Each network adapter usually has some. OR even more than one sometimes.
2) Even if physically you only have one network card, ypou also have loopback network - 127.x.x.x subnet. If you have some VPN installed like Hamachi or Comodo - that would give one more network adapter. Same for phone modem when connected. Same for virtual machines like XP Compatibility Mode. So you anyway would have to filter them one some criteria.
3) You can enlist network cards with FindAdaptor function of WMI: http://www.magsys.co.uk/delphi/magwmi.asp
Then you can read the properties of those adaptors.
There are also mentioned functions to set IP's, probably there are also functiones to read them.
Even if not, how to read properties is shown in the demo at the URL.
Which properties to read, you can determine using any WMI explorer out there.
Personally i ended with WMI Explorer of ks-soft.net plus WMI Tools of Microsoft.
You debug WMI request like you would do with SQLite, then pass it to WMI wrapper and read the result.
However, returning back to aforementioned Set IP Address functions, their sources probably already do contain properties names, just to save on exploring.