Pascal (Lazarus/Delphi)

DNS Query A Records

See more DNS Examples

Shows how to perform a DNS query to retrieve A records. Pascal (Lazarus/Delphi)

program ChilkatDemo;

// Demonstrates using the Chilkat Pascal wrapper via the C bridge DLL.
// Builds as a console application under Lazarus (FPC) or Delphi.

{$IFDEF FPC}
  {$MODE DELPHI}
{$ENDIF}
{$APPTYPE CONSOLE}

uses
  {$IFDEF UNIX}
  cthreads,
  {$ENDIF}
  SysUtils,
  CkDllLoader,
  Chilkat.Dns,
  Chilkat.JsonObject;

// ---------------------------------------------------------------------------

procedure RunDemo;
var
  success: Boolean;
  dns: TDns;
  json: TJsonObject;
  name: string;
  ttl: Integer;
  ipv4: string;
  i: Integer;
  count_i: Integer;

begin
  success := False;

  dns := TDns.Create;

  json := TJsonObject.Create;
  json.EmitCompact := False;

  success := dns.Query('A','microsoft.com',json);
  if (success = False) then
    begin
      WriteLn(dns.LastErrorText);
      Exit;
    end;

  WriteLn(json.Emit());

  //  Sample response.
  //  Parsing code below..

  //  {
  //    "answer": {
  //      "a": [
  //        {
  //          "name": "microsoft.com",
  //          "ttl": 1528,
  //          "ipv4": "20.112.250.133"
  //        },
  //        {
  //          "name": "microsoft.com",
  //          "ttl": 1528,
  //          "ipv4": "20.231.239.246"
  //        },
  //        {
  //          "name": "microsoft.com",
  //          "ttl": 1528,
  //          "ipv4": "20.76.201.171"
  //        },
  //        {
  //          "name": "microsoft.com",
  //          "ttl": 1528,
  //          "ipv4": "20.70.246.20"
  //        },
  //        {
  //          "name": "microsoft.com",
  //          "ttl": 1528,
  //          "ipv4": "20.236.44.162"
  //        }
  //      ]
  //    }
  //  }

  //  Use this online tool to generate parsing code from sample JSON: 
  //  Generate Parsing Code from JSON

  i := 0;
  count_i := json.SizeOfArray('answer.a');
  while i < count_i do
    begin
      json.I := i;
      name := json.StringOf('answer.a[i].name');
      ttl := json.IntOf('answer.a[i].ttl');
      ipv4 := json.StringOf('answer.a[i].ipv4');
      i := i + 1;
    end;



  dns.Free;
  json.Free;

end;

// ---------------------------------------------------------------------------

begin

  try
    RunDemo;
  except
    on E: Exception do
      WriteLn('Unhandled exception: ', E.ClassName, ': ', E.Message);
  end;

  WriteLn;
  {$IFDEF MSWINDOWS}
  WriteLn('Press Enter to exit...');
  ReadLn;
  {$ENDIF}
end.