CODEWITHSUNDEEP
delphinetwork-programmingdelphi-xe5
uPrompt
uPrompt

Reputation: 159

Delphi get IP from network name

Ok guys, I've dug and dug, including on this site, and can't find any solution to this.

Assume several computers are connected to a network and all are in the same workgroup. I can easily get a list of all their network names, like //MYCOMPUTER-PC. I'm trying to get all of the local IP address of these machines (not just the current machine) i.e. 192.168.0.1 without having to physically connect to every possible IP and test a connection.

So far everything I've tried has failed. Either I can only get the IP address of the machine I'm running on or, I get the ip address for Searchguide (198.105.244.65) which is where my ISP defaults when an IP address can't be found.

Here's the code I'm using that fails. If I leave the \ in the network name, I get an unknown result. If I remove the \ I get the Searchguide IP:

function GetIPAddress(NetworkName: String): String;
var
Error: DWORD;
HostEntry: PHostEnt;
Data: WSAData;
Address: In_Addr;
begin
     Error:=WSAStartup(MakeWord(1, 1), Data);
     if Error = 0 then 
     begin
          HostEntry:=gethostbyname(PansiChar(NetworkName));
          Error:=GetLastError();
          if Error = 0 then 
          begin
               Address:=PInAddr(HostEntry^.h_addr_list^)^;
               Result:=inet_ntoa(Address);
          end
          else 
          begin
               Result:='Unknown';
          end;
     end
     else
     begin
          Result:='Error';
     end;
     WSACleanup();
end;

So, assuming I know nothing about the router these computers are connected to, is it even possible to get a list of local IP's???

Thanks

edit

Here's an image of it's output

enter image description here

Upvotes: 1

Views: 3356

Answers (1)

Sertac Akyuz
Sertac Akyuz

Reputation: 54832

You're using XE5, string is unicode, you are not passing host name to gethostbyname but some garbage. Replace

HostEntry:=gethostbyname(PansiChar(NetworkName));

with

HostEntry:=gethostbyname(PansiChar(AnsiString(NetworkName)));


Additionally test the return of gethostbyname for success, not the last error. Use documentation of the api for proper usage. Also use WSAGetLastError to retrieve winsock error code (as documented), not GetLastError.

Upvotes: 2

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