[fpc-devel] Function to find if IP address is local

[Ondrej Pokorny]

On 09.01.2023 09:08, Michael Van Canneyt wrote:
> On Mon, 9 Jan 2023, Ondrej Pokorny via fpc-devel wrote:
>> Is there a routine in RTL to find out if a given IPv4 address is from 
>> the private address range (10.* etc)?
>
> No, not to my knowledge. Feel free to add it somewhere in fcl-net.

Here it is:

function NetAddrIsPrivate(const IP: in_addr): Boolean;
begin
   Result :=
     // 10.0.0.0 – 10.255.255.255
         (IP.s_bytes[1]=10)
     // 172.16.0.0 – 172.31.255.255
     or ((IP.s_bytes[1]=172) and (IP.s_bytes[2]>=16) and 
(IP.s_bytes[2]<=31))
     // 192.168.0.0 – 192.168.255.255
     or ((IP.s_bytes[1]=192) and (IP.s_bytes[2]=168));
end;

I didn't find a good unit in fcl-net to put it in.

IMO it would be better suited in sockets.pp in rtl-extra where in_addr 
is declared.

Feel free to add it there or in fcl-net, if you know a good place.

Thank you!
Ondrej