{ ***************************************************************************

  Copyright (c) 2015-2018 Kike Pérez

  Unit        : Quick.Network
  Description : Network related functions
  Author      : Kike Pérez
  Version     : 1.4
  Created     : 11/07/2017
  Modified    : 07/04/2018

  This file is part of QuickLib: https://github.com/exilon/QuickLib

 ***************************************************************************

  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at

  http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.

 *************************************************************************** }

unit Quick.Network;

{$i QuickLib.inc}

interface

uses
  Classes,
  SysUtils,
  Math,
  IdDNSResolver;

type
  TDNSResolve = class
  private
    fHost : string;
    fPort : Integer;
    function ResolveDNS(const aDNS : string; aRegType: TQueryRecordTypes): string;
  public
    constructor Create(const aNameServer : string = '8.8.8.8'; aServerPort : Integer = 53);
    function ResolveA(const aDNS : string): string;
    function ResolveAAAA(const aDNS : string): string;
    function ResolveCNAME(const aDNS : string): string;
    function ResolveNS(const aDNS : string): string;
    function ResolveTXT(const aDNS : string): string;
  end;

  function IntToIPv4(IPv4: LongWord): string;
  function IPv4ToInt(const IPv4: string) : LongWord;
  function IPv4ToIntReverse(const IPv4: string) : LongWord;
  procedure CIDRToRange(CIDR : string; out MinIP,MaxIP : string); overload;
  procedure CIDRToRange(CIDR : string; out MinIP,MaxIP : LongWord); overload;
  procedure GetIPRange(const cIP, cMask : string; out LowIP, HighIP : string);

implementation

function IntToIPv4(IPv4: LongWord): string;
var
  Retvar : string;
  iSeg,iShift,
  i, iMask : LongWord;
begin
  Retvar := '';
  iShift := 24;
  iMask := $FF000000;
  for i := 1 to 4 do
  begin
    iSeg := (IPv4 and iMask) shr iShift;
    Retvar := Retvar + IntToStr(iSeg);
    if i < 4 then Retvar := Retvar + '.';
    iMask := iMask shr 8;
    dec(iShift,8);
  end;
  Result := Retvar;
end;

function IPv4ToInt(const IPv4: string) : LongWord;
var
  S : TStrings;
begin
  S := TStringList.Create;
  try
    S.Delimiter := '.';
    S.DelimitedText := IPv4;
    if S.Count <> 4 then raise Exception.Create('Invalid IP4 Address string');
    Result := (StrToInt(S[0]) shl 24) + (StrToInt(S[1]) shl 16) + (StrToInt(S[2]) shl 8) + StrToInt(S[3]);
  finally
    S.Free;
  end;
end;

function IPv4ToIntReverse(const IPv4: string) : LongWord;
var
  S : TStrings;
begin
  S := TStringList.Create;
  try
    S.Delimiter := '.';
    S.DelimitedText := IPv4;
    if S.Count <> 4 then raise Exception.Create('Invalid IP4 Address string');
    Result := (StrToInt(S[3]) shl 24) + (StrToInt(S[2]) shl 16) + (StrToInt(S[1]) shl 8) + StrToInt(S[0]);
  finally
    S.Free;
  end;
end;

procedure CIDRToRange(CIDR : string; out MinIP,MaxIP : string);
var
  Mask : Integer;
begin
  Mask := StrToInt(Copy(CIDR,Pos('/',CIDR)+1,CIDR.Length));
  CIDR := Copy(CIDR,0,Pos('/',CIDR)-1);
  MinIP := IntToIPv4((IPv4ToInt(CIDR)) and ((-1 shl (32 - Mask))));
  MaxIP := IntToIPv4((IPv4ToInt(MinIP)) + Round(Power(2,(32 - Mask))) - 1);
end;

procedure CIDRToRange(CIDR : string; out MinIP,MaxIP : LongWord);
var
  Mask : Integer;
  aux : string;
begin
  Mask := StrToInt(Copy(CIDR,Pos('/',CIDR)+1,CIDR.Length));
  CIDR := Copy(CIDR,0,Pos('/',CIDR)-1);
  aux := IntToIPv4((IPv4ToInt(CIDR)) and ((-1 shl (32 - Mask))));
  MinIP := IPv4ToInt(aux);
  aux := IntToIPv4((IPv4ToInt(aux)) + Round(Power(2,(32 - Mask))) - 1);
  MaxIP := IPv4ToInt(aux);
end;

procedure GetIPRange(const cIP, cMask : string; out LowIP, HighIP : string);
begin
  try                      
    LowIP := IntToIPv4((IPv4ToInt(cIP) and (IPv4ToInt(cMask)) + 1));
    HighIP := IntToIPv4(IPv4ToInt(cIP) or not(IPv4ToInt(cMask))-1);
  except
    on E : Exception do raise Exception.Create(Format('GetIPRange error: %s',[e.Message]));
  end;
end;

{ TDNSResolve }

constructor TDNSResolve.Create(const aNameServer : string = '8.8.8.8'; aServerPort : Integer = 53);
begin
  fHost := aNameServer;
  fPort := aServerPort;
end;

function TDNSResolve.ResolveDNS(const aDNS : string; aRegType: TQueryRecordTypes): string;
var
  dnsresolver : TIdDNSResolver;
begin
  Result := '';
  dnsresolver := TIdDNSResolver.Create(nil);
  try
    dnsresolver.Host := fHost;
    dnsresolver.Port := fPort;
    dnsresolver.QueryResult.Clear;
    dnsresolver.QueryType := [aRegType];
    dnsresolver.Resolve(aDNS);
    if dnsresolver.QueryResult.Count > 0 then
    begin
      if dnsresolver.QueryResult[0].RecType = aRegType then
      begin
        case aRegType of
          qtNS : Result := TNSRecord(dnsresolver.QueryResult.Items[0]).HostName;
          qtA : Result := TARecord(dnsresolver.QueryResult.Items[0]).IPAddress;
          qtAAAA : Result := TAAAARecord(dnsresolver.QueryResult.Items[0]).Address;
          qtNAME : Result := TCNRecord(dnsresolver.QueryResult.Items[0]).HostName;
          qtTXT : Result := TTextRecord(dnsresolver.QueryResult.Items[0]).Text.Text;
          else raise Exception.Create('Not implemented yet!');
        end;

      end;
    end;
  finally
    dnsresolver.Free;
  end;
end;

function TDNSResolve.ResolveNS(const aDNS : string): string;
begin
  Result := ResolveDNS(aDNS,qtNS);
end;

function TDNSResolve.ResolveA(const aDNS : string): string;
begin
  Result := ResolveDNS(aDNS,qtA);
end;

function TDNSResolve.ResolveAAAA(const aDNS : string): string;
begin
  Result := ResolveDNS(aDNS,qtAAAA);
end;


function TDNSResolve.ResolveCNAME(const aDNS : string): string;
begin
  Result := ResolveDNS(aDNS,qtName);
end;

function TDNSResolve.ResolveTXT(const aDNS : string): string;
begin
  Result := ResolveDNS(aDNS,qtTXT);
end;

end.