DNSResolve.pas

   1 {
   2    Copyright (C) 2010-2018 MegaBrutal
   3
   4    This unit is free software: you can redistribute it and/or modify
   5    it under the terms of the GNU Lesser General Public License as published by
   6    the Free Software Foundation, either version 3 of the License, or
   7    (at your option) any later version.
   8
   9    This unit is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public License
  15    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  16 }
  17
  18
  19 {$MODE FPC}
  20
  21 unit DNSResolve;
  22
  23 interface
  24 uses WinSock, Sockets, ctypes;
  25
  26 type
  27
  28    PAddrInfo = ^TAddrInfo;
  29    TAddrInfo = record
  30       ai_flags: cint;
  31       ai_family: cint;
  32       ai_socktype: cint;
  33       ai_protocol: cint;
  34       ai_addrlen: size_t;
  35       ai_canonname: PChar;
  36       ai_addr: PSockAddr;
  37       ai_next: PAddrInfo;
  38    end;
  39
  40    TGAIResult = record
  41       GAIError: integer;
  42       AddrInfo: PAddrInfo;
  43    end;
  44
  45
  46    function getaddrinfo(NodeName, ServiceName: PChar; Hints: PAddrInfo; var AddrInfo: PAddrInfo): cint; stdcall;
  47       external 'ws2_32.dll' name 'getaddrinfo';
  48
  49    procedure freeaddrinfo(AddrInfo: PAddrInfo); stdcall;
  50       external 'ws2_32.dll' name 'freeaddrinfo';
  51
  52    function getnameinfo(SockAddr: PSockAddr; SockAddrLength: cuint32; NodeBuffer: PChar; NodeBufferSize: cuint32;
  53       ServiceBuffer: PChar; ServiceBufferSize: cuint32; Flags: cint): cint; stdcall;
  54       external 'ws2_32.dll' name 'getnameinfo';
  55
  56    function ResolveHost(HostName: ansistring; Family: cint): TGAIResult;
  57    procedure FreeHost(var GAIResult: TGAIResult);
  58    function ResolveIP(AddrInfo: PAddrInfo): ansistring;
  59    function IPToStr(SockAddr: PSockAddr): ansistring;
  60
  61
  62 implementation
  63
  64
  65 function ResolveHost(HostName: ansistring; Family: cint): TGAIResult;
  66 var hint: TAddrInfo;
  67 begin
  68    FillByte(hint, SizeOf(hint), 0);
  69    with hint do begin
  70       ai_family:= Family;
  71       ai_socktype:= SOCK_STREAM;
  72       ai_protocol:= IPPROTO_TCP;
  73    end;
  74    ResolveHost.GAIError:= getaddrinfo(PChar(HostName), nil, @hint, ResolveHost.AddrInfo);
  75 end;
  76
  77 procedure FreeHost(var GAIResult: TGAIResult);
  78 begin
  79    if GAIResult.AddrInfo <> nil then begin
  80       freeaddrinfo(GAIResult.AddrInfo);
  81       GAIResult.AddrInfo:= nil;
  82    end;
  83 end;
  84
  85 function ResolveIP(AddrInfo: PAddrInfo): ansistring;
  86 var
  87    r: integer;
  88    NodeBuffer: array[0..255] of char;
  89 begin
  90    NodeBuffer[0]:= #0;
  91    r:= getnameinfo(AddrInfo^.ai_addr, AddrInfo^.ai_addrlen, @NodeBuffer, SizeOf(NodeBuffer), nil, 0, 0);
  92    if r = 0 then ResolveIP:= PChar(@NodeBuffer)
  93    else ResolveIP:= IPToStr(AddrInfo^.ai_addr);
  94 end;
  95
  96 function IPToStr(SockAddr: PSockAddr): ansistring;
  97 begin
  98    if SockAddr^.sa_family = AF_INET then
  99       IPToStr:= NetAddrToStr(SockAddr^.sin_addr)
 100    else if SockAddr^.sa_family = AF_INET6 then
 101       IPToStr:= NetAddrToStr6(PSockAddr6(SockAddr)^.sin6_addr)
 102    else
 103       IPToStr:= 'unknown';
 104 end;
 105
 106
 107 end.