IP/Host Resolver

Program that converts IP to host and host to IP
A simple use of Windows API for playing with networks. Today I thought of  making a simple program with the help of Windows API that can return your hostname if you enter IP address and return your IP address if you enter your hostname.
 This program can be very useful for some project where they need user IP address or hostname for processing.

We have used the WinSock API to achieve this.

Here's the code written in Delphi

// Function to get the Host from IP address

function TFrmMain.IPAddrToName(IPAddr: string): string;

var

  SockAddrIn: TSockAddrIn;

  HostEnt: PHostEnt;

  WSAData: TWSAData;

begin

  WSAStartup($101, WSAData);

  SockAddrIn.sin_addr.s_addr := inet_addr(PAnsiChar(AnsiString(IPAddr)));

  HostEnt := gethostbyaddr(@SockAddrIn.sin_addr.S_addr, 4, AF_INET);

  if HostEnt <> nil then

    Result := StrPas(Hostent^.h_name)

  else

    Result := '';

end;

// Function to get the IP Address from a Host

function TFrmMain.GetIPFromHost(HostName: string): string;

type

  TaPInAddr = array[0..10] of PInAddr;

  PaPInAddr = ^TaPInAddr;

var

  phe: PHostEnt;

  pptr: PaPInAddr;

  i: Integer;

  GInitData: TWSAData;

begin

  WSAStartup($101, GInitData);

  Result := '';

  phe := GetHostByName(PAnsiChar(AnsiString((HostName))));

  if phe = nil then Exit;

  pPtr := PaPInAddr(phe^.h_addr_list);

  i := 0;

  while pPtr^[i] <> nil do

  begin

    Result := inet_ntoa(pptr^[i]^);

    Inc(i);

  end;

  WSACleanup;

end;

For complete project source code and exceutable

Refer this site Ip-Host Resolver or Softpedia.com
https://sourceforge.net/projects/iphostresolver