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{==============================================================================|
| Project : Ararat Synapse | 002.007.006 |
|==============================================================================|
| Content: DNS client |
|==============================================================================|
| Copyright (c)1999-2010, Lukas Gebauer |
| All rights reserved. |
| |
| Redistribution and use in source and binary forms, with or without |
| modification, are permitted provided that the following conditions are met: |
| |
| Redistributions of source code must retain the above copyright notice, this |
| list of conditions and the following disclaimer. |
| |
| Redistributions in binary form must reproduce the above copyright notice, |
| this list of conditions and the following disclaimer in the documentation |
| and/or other materials provided with the distribution. |
| |
| Neither the name of Lukas Gebauer nor the names of its contributors may |
| be used to endorse or promote products derived from this software without |
| specific prior written permission. |
| |
| THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" |
| AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
| ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR |
| ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
| DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR |
| SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER |
| CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
| LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
| OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH |
| DAMAGE. |
|==============================================================================|
| The Initial Developer of the Original Code is Lukas Gebauer (Czech Republic).|
| Portions created by Lukas Gebauer are Copyright (c)2000-2010. |
| All Rights Reserved. |
|==============================================================================|
| Contributor(s): |
|==============================================================================|
| History: see HISTORY.HTM from distribution package |
| (Found at URL: http://www.ararat.cz/synapse/) |
|==============================================================================}
{: @abstract(DNS client by UDP or TCP)
Support for sending DNS queries by UDP or TCP protocol. It can retrieve zone
transfers too!
Used RFC: RFC-1035, RFC-1183, RFC1706, RFC1712, RFC2163, RFC2230
}
{$IFDEF FPC}
{$MODE DELPHI}
{$ENDIF}
{$Q-}
{$H+}
{$IFDEF UNICODE}
{$WARN IMPLICIT_STRING_CAST OFF}
{$WARN IMPLICIT_STRING_CAST_LOSS OFF}
{$ENDIF}
unit dnssend;
interface
uses
SysUtils, Classes,
blcksock, synautil, synaip, synsock;
const
cDnsProtocol = '53';
QTYPE_A = 1;
QTYPE_NS = 2;
QTYPE_MD = 3;
QTYPE_MF = 4;
QTYPE_CNAME = 5;
QTYPE_SOA = 6;
QTYPE_MB = 7;
QTYPE_MG = 8;
QTYPE_MR = 9;
QTYPE_NULL = 10;
QTYPE_WKS = 11; //
QTYPE_PTR = 12;
QTYPE_HINFO = 13;
QTYPE_MINFO = 14;
QTYPE_MX = 15;
QTYPE_TXT = 16;
QTYPE_RP = 17;
QTYPE_AFSDB = 18;
QTYPE_X25 = 19;
QTYPE_ISDN = 20;
QTYPE_RT = 21;
QTYPE_NSAP = 22;
QTYPE_NSAPPTR = 23;
QTYPE_SIG = 24; // RFC-2065
QTYPE_KEY = 25; // RFC-2065
QTYPE_PX = 26;
QTYPE_GPOS = 27;
QTYPE_AAAA = 28;
QTYPE_LOC = 29; // RFC-1876
QTYPE_NXT = 30; // RFC-2065
QTYPE_SRV = 33;
QTYPE_NAPTR = 35; // RFC-2168
QTYPE_KX = 36;
QTYPE_SPF = 99;
QTYPE_AXFR = 252;
QTYPE_MAILB = 253; //
QTYPE_MAILA = 254; //
QTYPE_ALL = 255;
type
{:@abstract(Implementation of DNS protocol by UDP or TCP protocol.)
Note: Are you missing properties for specify server address and port? Look to
parent @link(TSynaClient) too!}
TDNSSend = class(TSynaClient)
private
FID: Word;
FRCode: Integer;
FBuffer: AnsiString;
FSock: TUDPBlockSocket;
FTCPSock: TTCPBlockSocket;
FUseTCP: Boolean;
FAnswerInfo: TStringList;
FNameserverInfo: TStringList;
FAdditionalInfo: TStringList;
FAuthoritative: Boolean;
FTruncated: Boolean;
function CompressName(const Value: AnsiString): AnsiString;
function CodeHeader: AnsiString;
function CodeQuery(const Name: AnsiString; QType: Integer): AnsiString;
function DecodeLabels(var From: Integer): AnsiString;
function DecodeString(var From: Integer): AnsiString;
function DecodeResource(var i: Integer; const Info: TStringList;
QType: Integer): AnsiString;
function RecvTCPResponse(const WorkSock: TBlockSocket): AnsiString;
function DecodeResponse(const Buf: AnsiString; const Reply: TStrings;
QType: Integer):boolean;
public
constructor Create;
destructor Destroy; override;
{:Query a DNSHost for QType resources correspond to a name. Supported QType
values are: Qtype_A, Qtype_NS, Qtype_MD, Qtype_MF, Qtype_CNAME, Qtype_SOA,
Qtype_MB, Qtype_MG, Qtype_MR, Qtype_NULL, Qtype_PTR, Qtype_HINFO,
Qtype_MINFO, Qtype_MX, Qtype_TXT, Qtype_RP, Qtype_AFSDB, Qtype_X25,
Qtype_ISDN, Qtype_RT, Qtype_NSAP, Qtype_NSAPPTR, Qtype_PX, Qtype_GPOS,
Qtype_KX.
Type for zone transfers QTYPE_AXFR is supported too, but only in TCP mode!
"Name" is domain name or host name for queried resource. If "name" is
IP address, automatically convert to reverse domain form (.in-addr.arpa).
If result is @true, Reply contains resource records. One record on one line.
If Resource record have multiple fields, they are stored on line divided by
comma. (example: MX record contains value 'rs.cesnet.cz' with preference
number 10, string in Reply is: '10,rs.cesnet.cz'). All numbers or IP address
in resource are converted to string form.}
function DNSQuery(Name: AnsiString; QType: Integer;
const Reply: TStrings): Boolean;
published
{:Socket object used for UDP operation. Good for seting OnStatus hook, etc.}
property Sock: TUDPBlockSocket read FSock;
{:Socket object used for TCP operation. Good for seting OnStatus hook, etc.}
property TCPSock: TTCPBlockSocket read FTCPSock;
{:if @true, then is used TCP protocol instead UDP. It is needed for zone
transfers, etc.}
property UseTCP: Boolean read FUseTCP Write FUseTCP;
{:After DNS operation contains ResultCode of DNS operation.
Values are: 0-no error, 1-format error, 2-server failure, 3-name error,
4-not implemented, 5-refused.}
property RCode: Integer read FRCode;
{:@True, if answer is authoritative.}
property Authoritative: Boolean read FAuthoritative;
{:@True, if answer is truncated to 512 bytes.}
property Truncated: Boolean read FTRuncated;
{:Detailed informations from name server reply. One record per line. Record
have comma delimited entries with type number, TTL and data filelds.
This information contains detailed information about query reply.}
property AnswerInfo: TStringList read FAnswerInfo;
{:Detailed informations from name server reply. One record per line. Record
have comma delimited entries with type number, TTL and data filelds.
This information contains detailed information about nameserver.}
property NameserverInfo: TStringList read FNameserverInfo;
{:Detailed informations from name server reply. One record per line. Record
have comma delimited entries with type number, TTL and data filelds.
This information contains detailed additional information.}
property AdditionalInfo: TStringList read FAdditionalInfo;
end;
{:A very useful function, and example of it's use is found in the TDNSSend object.
This function is used to get mail servers for a domain and sort them by
preference numbers. "Servers" contains only the domain names of the mail
servers in the right order (without preference number!). The first domain name
will always be the highest preferenced mail server. Returns boolean @TRUE if
all went well.}
function GetMailServers(const DNSHost, Domain: AnsiString;
const Servers: TStrings): Boolean;
implementation
constructor TDNSSend.Create;
begin
inherited Create;
FSock := TUDPBlockSocket.Create;
FSock.Owner := self;
FTCPSock := TTCPBlockSocket.Create;
FTCPSock.Owner := self;
FUseTCP := False;
FTimeout := 10000;
FTargetPort := cDnsProtocol;
FAnswerInfo := TStringList.Create;
FNameserverInfo := TStringList.Create;
FAdditionalInfo := TStringList.Create;
Randomize;
end;
destructor TDNSSend.Destroy;
begin
FAnswerInfo.Free;
FNameserverInfo.Free;
FAdditionalInfo.Free;
FTCPSock.Free;
FSock.Free;
inherited Destroy;
end;
function TDNSSend.CompressName(const Value: AnsiString): AnsiString;
var
n: Integer;
s: AnsiString;
begin
Result := '';
if Value = '' then
Result := #0
else
begin
s := '';
for n := 1 to Length(Value) do
if Value[n] = '.' then
begin
Result := Result + AnsiChar(Length(s)) + s;
s := '';
end
else
s := s + Value[n];
if s <> '' then
Result := Result + AnsiChar(Length(s)) + s;
Result := Result + #0;
end;
end;
function TDNSSend.CodeHeader: AnsiString;
begin
FID := Random(32767);
Result := CodeInt(FID); // ID
Result := Result + CodeInt($0100); // flags
Result := Result + CodeInt(1); // QDCount
Result := Result + CodeInt(0); // ANCount
Result := Result + CodeInt(0); // NSCount
Result := Result + CodeInt(0); // ARCount
end;
function TDNSSend.CodeQuery(const Name: AnsiString; QType: Integer): AnsiString;
begin
Result := CompressName(Name);
Result := Result + CodeInt(QType);
Result := Result + CodeInt(1); // Type INTERNET
end;
function TDNSSend.DecodeString(var From: Integer): AnsiString;
var
Len: integer;
begin
Len := Ord(FBuffer[From]);
Inc(From);
Result := Copy(FBuffer, From, Len);
Inc(From, Len);
end;
function TDNSSend.DecodeLabels(var From: Integer): AnsiString;
var
l, f: Integer;
begin
Result := '';
while True do
begin
if From >= Length(FBuffer) then
Break;
l := Ord(FBuffer[From]);
Inc(From);
if l = 0 then
Break;
if Result <> '' then
Result := Result + '.';
if (l and $C0) = $C0 then
begin
f := l and $3F;
f := f * 256 + Ord(FBuffer[From]) + 1;
Inc(From);
Result := Result + DecodeLabels(f);
Break;
end
else
begin
Result := Result + Copy(FBuffer, From, l);
Inc(From, l);
end;
end;
end;
function TDNSSend.DecodeResource(var i: Integer; const Info: TStringList;
QType: Integer): AnsiString;
var
Rname: AnsiString;
RType, Len, j, x, y, z, n: Integer;
R: AnsiString;
t1, t2, ttl: integer;
ip6: TIp6bytes;
begin
Result := '';
R := '';
Rname := DecodeLabels(i);
RType := DecodeInt(FBuffer, i);
Inc(i, 4);
t1 := DecodeInt(FBuffer, i);
Inc(i, 2);
t2 := DecodeInt(FBuffer, i);
Inc(i, 2);
ttl := t1 * 65536 + t2;
Len := DecodeInt(FBuffer, i);
Inc(i, 2); // i point to begin of data
j := i;
i := i + len; // i point to next record
if Length(FBuffer) >= (i - 1) then
case RType of
QTYPE_A:
begin
R := IntToStr(Ord(FBuffer[j]));
Inc(j);
R := R + '.' + IntToStr(Ord(FBuffer[j]));
Inc(j);
R := R + '.' + IntToStr(Ord(FBuffer[j]));
Inc(j);
R := R + '.' + IntToStr(Ord(FBuffer[j]));
end;
QTYPE_AAAA:
begin
for n := 0 to 15 do
ip6[n] := ord(FBuffer[j + n]);
R := IP6ToStr(ip6);
end;
QTYPE_NS, QTYPE_MD, QTYPE_MF, QTYPE_CNAME, QTYPE_MB,
QTYPE_MG, QTYPE_MR, QTYPE_PTR, QTYPE_X25, QTYPE_NSAP,
QTYPE_NSAPPTR:
R := DecodeLabels(j);
QTYPE_SOA:
begin
R := DecodeLabels(j);
R := R + ',' + DecodeLabels(j);
for n := 1 to 5 do
begin
x := DecodeInt(FBuffer, j) * 65536 + DecodeInt(FBuffer, j + 2);
Inc(j, 4);
R := R + ',' + IntToStr(x);
end;
end;
QTYPE_NULL:
begin
end;
QTYPE_WKS:
begin
end;
QTYPE_HINFO:
begin
R := DecodeString(j);
R := R + ',' + DecodeString(j);
end;
QTYPE_MINFO, QTYPE_RP, QTYPE_ISDN:
begin
R := DecodeLabels(j);
R := R + ',' + DecodeLabels(j);
end;
QTYPE_MX, QTYPE_AFSDB, QTYPE_RT, QTYPE_KX:
begin
x := DecodeInt(FBuffer, j);
Inc(j, 2);
R := IntToStr(x);
R := R + ',' + DecodeLabels(j);
end;
QTYPE_TXT, QTYPE_SPF:
begin
R := '';
while j < i do
R := R + DecodeString(j);
end;
QTYPE_GPOS:
begin
R := DecodeLabels(j);
R := R + ',' + DecodeLabels(j);
R := R + ',' + DecodeLabels(j);
end;
QTYPE_PX:
begin
x := DecodeInt(FBuffer, j);
Inc(j, 2);
R := IntToStr(x);
R := R + ',' + DecodeLabels(j);
R := R + ',' + DecodeLabels(j);
end;
QTYPE_SRV:
// Author: Dan <ml@mutox.org>
begin
x := DecodeInt(FBuffer, j);
Inc(j, 2);
y := DecodeInt(FBuffer, j);
Inc(j, 2);
z := DecodeInt(FBuffer, j);
Inc(j, 2);
R := IntToStr(x); // Priority
R := R + ',' + IntToStr(y); // Weight
R := R + ',' + IntToStr(z); // Port
R := R + ',' + DecodeLabels(j); // Server DNS Name
end;
end;
if R <> '' then
Info.Add(RName + ',' + IntToStr(RType) + ',' + IntToStr(ttl) + ',' + R);
if QType = RType then
Result := R;
end;
function TDNSSend.RecvTCPResponse(const WorkSock: TBlockSocket): AnsiString;
var
l: integer;
begin
Result := '';
l := WorkSock.recvbyte(FTimeout) * 256 + WorkSock.recvbyte(FTimeout);
if l > 0 then
Result := WorkSock.RecvBufferStr(l, FTimeout);
end;
function TDNSSend.DecodeResponse(const Buf: AnsiString; const Reply: TStrings;
QType: Integer):boolean;
var
n, i: Integer;
flag, qdcount, ancount, nscount, arcount: Integer;
s: AnsiString;
begin
Result := False;
Reply.Clear;
FAnswerInfo.Clear;
FNameserverInfo.Clear;
FAdditionalInfo.Clear;
FAuthoritative := False;
if (Length(Buf) > 13) and (FID = DecodeInt(Buf, 1)) then
begin
Result := True;
flag := DecodeInt(Buf, 3);
FRCode := Flag and $000F;
FAuthoritative := (Flag and $0400) > 0;
FTruncated := (Flag and $0200) > 0;
if FRCode = 0 then
begin
qdcount := DecodeInt(Buf, 5);
ancount := DecodeInt(Buf, 7);
nscount := DecodeInt(Buf, 9);
arcount := DecodeInt(Buf, 11);
i := 13; //begin of body
if (qdcount > 0) and (Length(Buf) > i) then //skip questions
for n := 1 to qdcount do
begin
while (Buf[i] <> #0) and ((Ord(Buf[i]) and $C0) <> $C0) do
Inc(i);
Inc(i, 5);
end;
if (ancount > 0) and (Length(Buf) > i) then // decode reply
for n := 1 to ancount do
begin
s := DecodeResource(i, FAnswerInfo, QType);
if s <> '' then
Reply.Add(s);
end;
if (nscount > 0) and (Length(Buf) > i) then // decode nameserver info
for n := 1 to nscount do
DecodeResource(i, FNameserverInfo, QType);
if (arcount > 0) and (Length(Buf) > i) then // decode additional info
for n := 1 to arcount do
DecodeResource(i, FAdditionalInfo, QType);
end;
end;
end;
function TDNSSend.DNSQuery(Name: AnsiString; QType: Integer;
const Reply: TStrings): Boolean;
var
WorkSock: TBlockSocket;
t: TStringList;
b: boolean;
begin
Result := False;
if IsIP(Name) then
Name := ReverseIP(Name) + '.in-addr.arpa';
if IsIP6(Name) then
Name := ReverseIP6(Name) + '.ip6.arpa';
FBuffer := CodeHeader + CodeQuery(Name, QType);
if FUseTCP then
WorkSock := FTCPSock
else
WorkSock := FSock;
WorkSock.Bind(FIPInterface, cAnyPort);
WorkSock.Connect(FTargetHost, FTargetPort);
if FUseTCP then
FBuffer := Codeint(length(FBuffer)) + FBuffer;
WorkSock.SendString(FBuffer);
if FUseTCP then
FBuffer := RecvTCPResponse(WorkSock)
else
FBuffer := WorkSock.RecvPacket(FTimeout);
if FUseTCP and (QType = QTYPE_AXFR) then //zone transfer
begin
t := TStringList.Create;
try
repeat
b := DecodeResponse(FBuffer, Reply, QType);
if (t.Count > 1) and (AnswerInfo.Count > 0) then //find end of transfer
b := b and (t[0] <> AnswerInfo[AnswerInfo.count - 1]);
if b then
begin
t.AddStrings(AnswerInfo);
FBuffer := RecvTCPResponse(WorkSock);
if FBuffer = '' then
Break;
if WorkSock.LastError <> 0 then
Break;
end;
until not b;
Reply.Assign(t);
Result := True;
finally
t.free;
end;
end
else //normal query
if WorkSock.LastError = 0 then
Result := DecodeResponse(FBuffer, Reply, QType);
end;
{==============================================================================}
function GetMailServers(const DNSHost, Domain: AnsiString;
const Servers: TStrings): Boolean;
var
DNS: TDNSSend;
t: TStringList;
n, m, x: Integer;
begin
Result := False;
Servers.Clear;
t := TStringList.Create;
DNS := TDNSSend.Create;
try
DNS.TargetHost := DNSHost;
if DNS.DNSQuery(Domain, QType_MX, t) then
begin
{ normalize preference number to 5 digits }
for n := 0 to t.Count - 1 do
begin
x := Pos(',', t[n]);
if x > 0 then
for m := 1 to 6 - x do
t[n] := '0' + t[n];
end;
{ sort server list }
t.Sorted := True;
{ result is sorted list without preference numbers }
for n := 0 to t.Count - 1 do
begin
x := Pos(',', t[n]);
Servers.Add(Copy(t[n], x + 1, Length(t[n]) - x));
end;
Result := True;
end;
finally
DNS.Free;
t.Free;
end;
end;
end.
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