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DnsProtocol.pas
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// --------------------------------------------------------------------------
//
// --------------------------------------------------------------------------
unit
DnsProtocol;
// --------------------------------------------------------------------------
//
// --------------------------------------------------------------------------
interface
// --------------------------------------------------------------------------
//
// --------------------------------------------------------------------------
uses
IPUtils;
// --------------------------------------------------------------------------
//
// --------------------------------------------------------------------------
const
MIN_DNS_PACKET_LEN = 16;
MAX_DNS_PACKET_LEN = 16384;
MAX_DNS_BUFFER_LEN = 65536;
// --------------------------------------------------------------------------
//
// --------------------------------------------------------------------------
const
DNS_QUERY_TYPE_A = $0001;
DNS_QUERY_TYPE_NS = $0002;
DNS_QUERY_TYPE_CNAME = $0005;
DNS_QUERY_TYPE_SOA = $0006;
DNS_QUERY_TYPE_PTR = $000C;
DNS_QUERY_TYPE_MX = $000F;
DNS_QUERY_TYPE_TXT = $0010;
DNS_QUERY_TYPE_AAAA = $001C;
DNS_QUERY_TYPE_SRV = $0021;
DNS_QUERY_TYPE_HTTPS = $0041;
DNS_QUERY_TYPE_ANY = $00FF;
// --------------------------------------------------------------------------
//
// --------------------------------------------------------------------------
type
TDnsProtocol = (UdpProtocol, TcpProtocol, Socks5Protocol, DnsOverHttpsProtocol);
// --------------------------------------------------------------------------
//
// --------------------------------------------------------------------------
type
TDnsOverHttpsProtocolConnectionType = (SystemDnsOverHttpsProtocolConnectionType, DirectDnsOverHttpsProtocolConnectionType);
// --------------------------------------------------------------------------
//
// --------------------------------------------------------------------------
type
TDnsProtocolUtility = class
public
class function ParseDnsProtocol(const Text: String): TDnsProtocol;
class function ParseDnsOverHttpsProtocolConnectionType(const Text: String): TDnsOverHttpsProtocolConnectionType;
class function ParseDnsQueryType(const Text: String): Word;
class function DnsQueryTypeToString(Value: Word): String;
private
class function GetWordFromPacket(Buffer: Pointer; Offset: Integer; BufferLen: Integer): Word;
class function GetIPv4AddressFromPacket(Buffer: Pointer; Offset: Integer; BufferLen: Integer): TIPv4Address;
class function GetIPv6AddressFromPacket(Buffer: Pointer; Offset: Integer; BufferLen: Integer): TIPv6Address;
public
class function GetIdFromPacket(Buffer: Pointer): Word;
class procedure SetIdIntoPacket(Value: Word; Buffer: Pointer);
class function GetStringFromPacket(Value: String; Buffer: Pointer; var OffsetL1: Integer; var OffsetLX: Integer; Level: Integer; BufferLen: Integer): String; overload;
class function GetStringFromPacket(Buffer: Pointer; var OffsetL1: Integer; var OffsetLX: Integer; BufferLen: Integer): String; overload;
class function GetStringFromPacket(Buffer: Pointer; var OffsetL1: Integer; BufferLen: Integer): String; overload;
class procedure SetStringIntoPacket(const Value: String; Buffer: Pointer; var Offset: Integer; BufferLen: Integer);
public
class procedure GetDomainNameAndQueryTypeFromRequestPacket(Buffer: Pointer; BufferLen: Integer; var DomainName: String; var QueryType: Word);
public
class function IsPrivateReverseLookup(const DomainName: String): Boolean;
public
class procedure BuildNegativeResponsePacket(const DomainName: String; QueryType: Word; Buffer: Pointer; var BufferLen: Integer);
class procedure BuildPositiveNullResponsePacket(const DomainName: String; QueryType: Word; Buffer: Pointer; var BufferLen: Integer); overload;
class procedure BuildPositiveIPv4ResponsePacket(const DomainName: String; QueryType: Word; HostAddress: TIPv4Address; TimeToLive: Integer; Buffer: Pointer; var BufferLen: Integer);
class procedure BuildPositiveIPv6ResponsePacket(const DomainName: String; QueryType: Word; HostAddress: TIPv6Address; TimeToLive: Integer; Buffer: Pointer; var BufferLen: Integer);
class procedure BuildPositiveHttpsResponsePacket(const DomainName: String; QueryType: Word; Buffer: Pointer; var BufferLen: Integer);
public
class function PrintGenericPacketBytesAsStringFromPacket(Buffer: Pointer; BufferLen: Integer): String;
class function PrintGenericPacketBytesAsStringFromPacketWithOffset(Buffer: Pointer; BufferLen: Integer; Offset: Integer; NumBytes: Integer): String;
public
class function PrintResponsePacketDescriptionAsStringFromPacket(Buffer: Pointer; BufferLen: Integer; IncludePacketBytesAlways: Boolean): String;
class function PrintRequestPacketDescriptionAsStringFromPacket(const DomainName: String; QueryType: Word; Buffer: Pointer; BufferLen: Integer; IncludePacketBytesAlways: Boolean): String;
public
class function IsValidRequestPacket(Buffer: Pointer; BufferLen: Integer): Boolean;
class function IsValidResponsePacket(Buffer: Pointer; BufferLen: Integer): Boolean;
public
class function IsFailureResponsePacket(Buffer: Pointer; BufferLen: Integer): Boolean;
class function IsNegativeResponsePacket(Buffer: Pointer; BufferLen: Integer): Boolean;
class function IsTruncatedResponsePacket(Buffer: Pointer; BufferLen: Integer): Boolean;
end;
// --------------------------------------------------------------------------
//
// --------------------------------------------------------------------------
implementation
// --------------------------------------------------------------------------
//
// --------------------------------------------------------------------------
uses
Math,
SysUtils,
CommonUtils;
// --------------------------------------------------------------------------
//
// --------------------------------------------------------------------------
class function TDnsProtocolUtility.ParseDnsProtocol(const Text: String): TDnsProtocol;
var
UpperCaseText: String;
begin
UpperCaseText := UpperCase(Text); if (UpperCaseText = 'UDP') then Result := UdpProtocol else if (UpperCaseText = 'DOH') then Result := DnsOverHttpsProtocol else if (UpperCaseText = 'TCP') then Result := TcpProtocol else if (UpperCaseText = 'SOCKS5') then Result := Socks5Protocol else Result := UdpProtocol;
end;
// --------------------------------------------------------------------------
//
// --------------------------------------------------------------------------
class function TDnsProtocolUtility.ParseDnsOverHttpsProtocolConnectionType(const Text: String): TDnsOverHttpsProtocolConnectionType;
var
UpperCaseText: String;
begin
UpperCaseText := UpperCase(Text); if (UpperCaseText = 'SYSTEM') or (UpperCaseText = 'CONFIG') then Result := SystemDnsOverHttpsProtocolConnectionType else if (UpperCaseText = 'DIRECT') then Result := DirectDnsOverHttpsProtocolConnectionType else Result := SystemDnsOverHttpsProtocolConnectionType;
end;
// --------------------------------------------------------------------------
//
// --------------------------------------------------------------------------
class function TDnsProtocolUtility.ParseDnsQueryType(const Text: String): Word;
begin
if (Text = 'A' ) then Result := DNS_QUERY_TYPE_A
else if (Text = 'AAAA' ) then Result := DNS_QUERY_TYPE_AAAA
else if (Text = 'ANY' ) then Result := DNS_QUERY_TYPE_ANY
else if (Text = 'CNAME') then Result := DNS_QUERY_TYPE_CNAME
else if (Text = 'HTTPS') then Result := DNS_QUERY_TYPE_HTTPS
else if (Text = 'MX' ) then Result := DNS_QUERY_TYPE_MX
else if (Text = 'NS' ) then Result := DNS_QUERY_TYPE_NS
else if (Text = 'PTR' ) then Result := DNS_QUERY_TYPE_PTR
else if (Text = 'SOA' ) then Result := DNS_QUERY_TYPE_SOA
else if (Text = 'SRV' ) then Result := DNS_QUERY_TYPE_SRV
else if (Text = 'TXT' ) then Result := DNS_QUERY_TYPE_TXT
else Result := StrToIntDef(Text, 0);
end;
// --------------------------------------------------------------------------
//
// --------------------------------------------------------------------------
class function TDnsProtocolUtility.DnsQueryTypeToString(Value: Word): String;
begin
case Value of
DNS_QUERY_TYPE_A : Result := 'A';
DNS_QUERY_TYPE_AAAA : Result := 'AAAA';
DNS_QUERY_TYPE_ANY : Result := 'ANY';
DNS_QUERY_TYPE_CNAME: Result := 'CNAME';
DNS_QUERY_TYPE_HTTPS: Result := 'HTTPS';
DNS_QUERY_TYPE_MX : Result := 'MX';
DNS_QUERY_TYPE_NS : Result := 'NS';
DNS_QUERY_TYPE_PTR : Result := 'PTR';
DNS_QUERY_TYPE_SOA : Result := 'SOA';
DNS_QUERY_TYPE_SRV : Result := 'SRV';
DNS_QUERY_TYPE_TXT : Result := 'TXT';
else Result := IntToStr(Value);
end;
end;
// --------------------------------------------------------------------------
//
// --------------------------------------------------------------------------
class function TDnsProtocolUtility.GetIdFromPacket(Buffer: Pointer): Word;
begin
Result := (PByteArray(Buffer)^[0] shl 8) + PByteArray(Buffer)^[1];
end;
// --------------------------------------------------------------------------
//
// --------------------------------------------------------------------------
class procedure TDnsProtocolUtility.SetIdIntoPacket(Value: Word; Buffer: Pointer);
begin
PByteArray(Buffer)^[0] := Value shr 8; PByteArray(Buffer)^[1] := Value and 255;
end;
// --------------------------------------------------------------------------
//
// --------------------------------------------------------------------------
class function TDnsProtocolUtility.GetWordFromPacket(Buffer: Pointer; Offset: Integer; BufferLen: Integer): Word;
begin
Result := (PByteArray(Buffer)^[Offset] shl 8) + PByteArray(Buffer)^[Offset + 1];
end;
// --------------------------------------------------------------------------
//
// --------------------------------------------------------------------------
class function TDnsProtocolUtility.GetIPv4AddressFromPacket(Buffer: Pointer; Offset: Integer; BufferLen: Integer): TIPv4Address;
begin
Result := (PByteArray(Buffer)^[Offset] shl 24) + (PByteArray(Buffer)^[Offset + 1] shl 16) + (PByteArray(Buffer)^[Offset + 2] shl 8) + PByteArray(Buffer)^[Offset + 3];
end;
// --------------------------------------------------------------------------
//
// --------------------------------------------------------------------------
class function TDnsProtocolUtility.GetIPv6AddressFromPacket(Buffer: Pointer; Offset: Integer; BufferLen: Integer): TIPv6Address;
var
IPv6Address: TIPv6Address;
begin
Move(PByteArray(Buffer)^[Offset], IPv6Address, SizeOf(TIPv6Address)); Result := IPv6Address;
end;
// --------------------------------------------------------------------------
//
// --------------------------------------------------------------------------
class function TDnsProtocolUtility.GetStringFromPacket(Value: String; Buffer: Pointer; var OffsetL1: Integer; var OffsetLX: Integer; Level: Integer; BufferLen: Integer): String;
var
Index: Integer;
begin
if (OffsetLX < BufferLen) then begin
if (PByteArray(Buffer)^[OffsetLX] > 0) then begin
if ((PByteArray(Buffer)^[OffsetLX] and $C0) > 0) then begin
if ((OffsetLX + 1) < BufferLen) then begin
if (Level = 1) then Inc(OffsetL1, 2); OffsetLX := ((PByteArray(Buffer)^[OffsetLX] and $1F) shl 8) + PByteArray(Buffer)^[OffsetLX + 1];
Value := TDnsProtocolUtility.GetStringFromPacket(Value, Buffer, OffsetL1, OffsetLX, Level + 1, BufferLen);
end else begin
if (Level = 1) then Inc(OffsetL1); Inc(OffsetLX);
end;
end else if ((OffsetLX + PByteArray(Buffer)^[OffsetLX] + 1) < BufferLen) then begin
if (Value <> '') then Value := Value + '.';
for Index := 1 to PByteArray(Buffer)^[OffsetLX] do Value := Value + Char(PByteArray(Buffer)^[OffsetLX + Index]);
if (Level = 1) then Inc(OffsetL1, PByteArray(Buffer)^[OffsetLX] + 1); Inc(OffsetLX, PByteArray(Buffer)^[OffsetLX] + 1);
Value := TDnsProtocolUtility.GetStringFromPacket(Value, Buffer, OffsetL1, OffsetLX, Level, BufferLen);
end;
end else begin
if (Level = 1) then Inc(OffsetL1); Inc(OffsetLX);
end;
end;
Result := Value;
end;
// --------------------------------------------------------------------------
//
// --------------------------------------------------------------------------
class function TDnsProtocolUtility.GetStringFromPacket(Buffer: Pointer; var OffsetL1: Integer; var OffsetLX: Integer; BufferLen: Integer): String;
begin
Result := TDnsProtocolUtility.GetStringFromPacket('', Buffer, OffsetL1, OffsetLX, 1, BufferLen);
end;
// --------------------------------------------------------------------------
//
// --------------------------------------------------------------------------
class function TDnsProtocolUtility.GetStringFromPacket(Buffer: Pointer; var OffsetL1: Integer; BufferLen: Integer): String;
var
OffsetLX: Integer;
begin
OffsetLX := OffsetL1; Result := TDnsProtocolUtility.GetStringFromPacket(Buffer, OffsetL1, OffsetLX, BufferLen);
end;
// --------------------------------------------------------------------------
//
// --------------------------------------------------------------------------
class procedure TDnsProtocolUtility.SetStringIntoPacket(const Value: String; Buffer: Pointer; var Offset: Integer; BufferLen: Integer);
var
PIndex: Integer; CIndex: Integer;
begin
PIndex := 0;
for CIndex := 1 to Length(Value) do begin
if (Value[CIndex] <> '.') then begin
PByteArray(Buffer)^[Offset + PIndex + 1] := Byte(Value[CIndex]); Inc(PIndex);
end else begin
PByteArray(Buffer)^[Offset] := PIndex; Inc(Offset, PIndex + 1); PIndex := 0;
end;
end;
PByteArray(Buffer)^[Offset] := PIndex; Inc(Offset, PIndex + 1);
PByteArray(Buffer)^[Offset] := $00; Inc(Offset);
end;
// --------------------------------------------------------------------------
//
// --------------------------------------------------------------------------
class procedure TDnsProtocolUtility.GetDomainNameAndQueryTypeFromRequestPacket(Buffer: Pointer; BufferLen: Integer; var DomainName: String; var QueryType: Word);
var
OffsetL1: Integer;
begin
OffsetL1 := $0C; DomainName := TDnsProtocolUtility.GetStringFromPacket(Buffer, OffsetL1, BufferLen); QueryType := TDnsProtocolUtility.GetWordFromPacket(Buffer, OffsetL1, BufferLen);
end;
// --------------------------------------------------------------------------
//
// --------------------------------------------------------------------------
class function TDnsProtocolUtility.IsPrivateReverseLookup(const DomainName: String): Boolean;
var
DomainNameLength: Integer; AddressText: String; AddressTextLength: Integer;
begin
Result := False;
DomainNameLength := Length(DomainName); if (DomainNameLength >= 20) and (DomainNameLength <= 28) then begin
if CommonUtils.StringEndsWith(DomainName, DomainNameLength, '.in-addr.arpa', 13) then begin
AddressText := Copy(DomainName, 1, DomainNameLength - 13); AddressTextLength := Length(AddressText);
Result := CommonUtils.StringEndsWith(AddressText, AddressTextLength, '.168.192', 8) or
CommonUtils.StringEndsWith(AddressText, AddressTextLength, '.254.169', 8) or
CommonUtils.StringEndsWith(AddressText, AddressTextLength, '.16.172', 7) or
CommonUtils.StringEndsWith(AddressText, AddressTextLength, '.17.172', 7) or
CommonUtils.StringEndsWith(AddressText, AddressTextLength, '.18.172', 7) or
CommonUtils.StringEndsWith(AddressText, AddressTextLength, '.19.172', 7) or
CommonUtils.StringEndsWith(AddressText, AddressTextLength, '.20.172', 7) or
CommonUtils.StringEndsWith(AddressText, AddressTextLength, '.21.172', 7) or
CommonUtils.StringEndsWith(AddressText, AddressTextLength, '.22.172', 7) or
CommonUtils.StringEndsWith(AddressText, AddressTextLength, '.23.172', 7) or
CommonUtils.StringEndsWith(AddressText, AddressTextLength, '.24.172', 7) or
CommonUtils.StringEndsWith(AddressText, AddressTextLength, '.25.172', 7) or
CommonUtils.StringEndsWith(AddressText, AddressTextLength, '.26.172', 7) or
CommonUtils.StringEndsWith(AddressText, AddressTextLength, '.27.172', 7) or
CommonUtils.StringEndsWith(AddressText, AddressTextLength, '.28.172', 7) or
CommonUtils.StringEndsWith(AddressText, AddressTextLength, '.29.172', 7) or
CommonUtils.StringEndsWith(AddressText, AddressTextLength, '.30.172', 7) or
CommonUtils.StringEndsWith(AddressText, AddressTextLength, '.31.172', 7) or
CommonUtils.StringEndsWith(AddressText, AddressTextLength, '.127', 4) or
CommonUtils.StringEndsWith(AddressText, AddressTextLength, '.10', 3) or
CommonUtils.StringEndsWith(AddressText, AddressTextLength, '.0', 2) or
(AddressText = '255.255.255.255');
end;
end else if (DomainNameLength >= 72) then begin
if CommonUtils.StringEndsWith(DomainName, DomainNameLength, '.ip6.arpa', 9) then begin
AddressText := Copy(DomainName, 1, DomainNameLength - 9); AddressTextLength := Length(AddressText);
Result := (AddressText = '1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0') or
CommonUtils.StringEndsWith(AddressText, AddressTextLength, '.8.e.f', 6) or
CommonUtils.StringEndsWith(AddressText, AddressTextLength, '.9.e.f', 6) or
CommonUtils.StringEndsWith(AddressText, AddressTextLength, '.a.e.f', 6) or
CommonUtils.StringEndsWith(AddressText, AddressTextLength, '.b.e.f', 6) or
(AddressText = '0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0');
end;
end;
end;
// --------------------------------------------------------------------------
//
// --------------------------------------------------------------------------
class procedure TDnsProtocolUtility.BuildNegativeResponsePacket(const DomainName: String; QueryType: Word; Buffer: Pointer; var BufferLen: Integer);
var
Offset: Integer;
begin
PByteArray(Buffer)^[$00] := $00;
PByteArray(Buffer)^[$01] := $00;
PByteArray(Buffer)^[$02] := $85;
PByteArray(Buffer)^[$03] := $83;
PByteArray(Buffer)^[$04] := $00;
PByteArray(Buffer)^[$05] := $01;
PByteArray(Buffer)^[$06] := $00;
PByteArray(Buffer)^[$07] := $00;
PByteArray(Buffer)^[$08] := $00;
PByteArray(Buffer)^[$09] := $00;
PByteArray(Buffer)^[$0A] := $00;
PByteArray(Buffer)^[$0B] := $00;
Offset := $0C;
TDnsProtocolUtility.SetStringIntoPacket(DomainName, Buffer, Offset, BufferLen);
PByteArray(Buffer)^[Offset] := QueryType shr $08; Inc(Offset);
PByteArray(Buffer)^[Offset] := QueryType and $FF; Inc(Offset);
PByteArray(Buffer)^[Offset] := $00; Inc(Offset);
PByteArray(Buffer)^[Offset] := $01; Inc(Offset);
BufferLen := Offset;
end;
// --------------------------------------------------------------------------
//
// --------------------------------------------------------------------------
class procedure TDnsProtocolUtility.BuildPositiveNullResponsePacket(const DomainName: String; QueryType: Word; Buffer: Pointer; var BufferLen: Integer);
var
Offset: Integer;
begin
PByteArray(Buffer)^[$00] := $00;
PByteArray(Buffer)^[$01] := $00;
PByteArray(Buffer)^[$02] := $85;
PByteArray(Buffer)^[$03] := $80;
PByteArray(Buffer)^[$04] := $00;
PByteArray(Buffer)^[$05] := $01;
PByteArray(Buffer)^[$06] := $00;
PByteArray(Buffer)^[$07] := $00;
PByteArray(Buffer)^[$08] := $00;
PByteArray(Buffer)^[$09] := $00;
PByteArray(Buffer)^[$0A] := $00;
PByteArray(Buffer)^[$0B] := $00;
Offset := $0C;
TDnsProtocolUtility.SetStringIntoPacket(DomainName, Buffer, Offset, BufferLen);
PByteArray(Buffer)^[Offset] := QueryType shr $08; Inc(Offset);
PByteArray(Buffer)^[Offset] := QueryType and $FF; Inc(Offset);
PByteArray(Buffer)^[Offset] := $00; Inc(Offset);
PByteArray(Buffer)^[Offset] := $01; Inc(Offset);
BufferLen := Offset;
end;
// --------------------------------------------------------------------------
//
// --------------------------------------------------------------------------
class procedure TDnsProtocolUtility.BuildPositiveIPv4ResponsePacket(const DomainName: String; QueryType: Word; HostAddress: TIPv4Address; TimeToLive: Integer; Buffer: Pointer; var BufferLen: Integer);
var
Offset: Integer;
begin
PByteArray(Buffer)^[$00] := $00;
PByteArray(Buffer)^[$01] := $00;
PByteArray(Buffer)^[$02] := $85;
PByteArray(Buffer)^[$03] := $80;
PByteArray(Buffer)^[$04] := $00;
PByteArray(Buffer)^[$05] := $01;
PByteArray(Buffer)^[$06] := $00;
PByteArray(Buffer)^[$07] := $01;
PByteArray(Buffer)^[$08] := $00;
PByteArray(Buffer)^[$09] := $00;
PByteArray(Buffer)^[$0A] := $00;
PByteArray(Buffer)^[$0B] := $00;
Offset := $0C;
TDnsProtocolUtility.SetStringIntoPacket(DomainName, Buffer, Offset, BufferLen);
PByteArray(Buffer)^[Offset] := QueryType shr $08; Inc(Offset);
PByteArray(Buffer)^[Offset] := QueryType and $FF; Inc(Offset);
PByteArray(Buffer)^[Offset] := $00; Inc(Offset);
PByteArray(Buffer)^[Offset] := $01; Inc(Offset);
PByteArray(Buffer)^[Offset] := $C0; Inc(Offset);
PByteArray(Buffer)^[Offset] := $0C; Inc(Offset);
PByteArray(Buffer)^[Offset] := QueryType shr $08; Inc(Offset);
PByteArray(Buffer)^[Offset] := QueryType and $FF; Inc(Offset);
PByteArray(Buffer)^[Offset] := $00; Inc(Offset);
PByteArray(Buffer)^[Offset] := $01; Inc(Offset);
PByteArray(Buffer)^[Offset] := TimeToLive shr $18; Inc(Offset);
PByteArray(Buffer)^[Offset] := TimeToLive shr $10 and $FF; Inc(Offset);
PByteArray(Buffer)^[Offset] := TimeToLive shr $08 and $FF; Inc(Offset);
PByteArray(Buffer)^[Offset] := TimeToLive and $FF; Inc(Offset);
PByteArray(Buffer)^[Offset] := $00; Inc(Offset);
PByteArray(Buffer)^[Offset] := $04; Inc(Offset);
Move(HostAddress, PByteArray(Buffer)^[Offset], 4); Inc(Offset, 4);
BufferLen := Offset;
end;
// --------------------------------------------------------------------------
//
// --------------------------------------------------------------------------
class procedure TDnsProtocolUtility.BuildPositiveIPv6ResponsePacket(const DomainName: String; QueryType: Word; HostAddress: TIPv6Address; TimeToLive: Integer; Buffer: Pointer; var BufferLen: Integer);
var
Offset: Integer;
begin
PByteArray(Buffer)^[$00] := $00;
PByteArray(Buffer)^[$01] := $00;
PByteArray(Buffer)^[$02] := $85;
PByteArray(Buffer)^[$03] := $80;
PByteArray(Buffer)^[$04] := $00;
PByteArray(Buffer)^[$05] := $01;
PByteArray(Buffer)^[$06] := $00;
PByteArray(Buffer)^[$07] := $01;
PByteArray(Buffer)^[$08] := $00;
PByteArray(Buffer)^[$09] := $00;
PByteArray(Buffer)^[$0A] := $00;
PByteArray(Buffer)^[$0B] := $00;
Offset := $0C;
TDnsProtocolUtility.SetStringIntoPacket(DomainName, Buffer, Offset, BufferLen);
PByteArray(Buffer)^[Offset] := QueryType shr $08; Inc(Offset);
PByteArray(Buffer)^[Offset] := QueryType and $FF; Inc(Offset);
PByteArray(Buffer)^[Offset] := $00; Inc(Offset);
PByteArray(Buffer)^[Offset] := $01; Inc(Offset);
PByteArray(Buffer)^[Offset] := $C0; Inc(Offset);
PByteArray(Buffer)^[Offset] := $0C; Inc(Offset);
PByteArray(Buffer)^[Offset] := QueryType shr $08; Inc(Offset);
PByteArray(Buffer)^[Offset] := QueryType and $FF; Inc(Offset);
PByteArray(Buffer)^[Offset] := $00; Inc(Offset);
PByteArray(Buffer)^[Offset] := $01; Inc(Offset);
PByteArray(Buffer)^[Offset] := TimeToLive shr $18; Inc(Offset);
PByteArray(Buffer)^[Offset] := TimeToLive shr $10 and $FF; Inc(Offset);
PByteArray(Buffer)^[Offset] := TimeToLive shr $08 and $FF; Inc(Offset);
PByteArray(Buffer)^[Offset] := TimeToLive and $FF; Inc(Offset);
PByteArray(Buffer)^[Offset] := $00; Inc(Offset);
PByteArray(Buffer)^[Offset] := $10; Inc(Offset);
Move(HostAddress, PByteArray(Buffer)^[Offset], 16); Inc(Offset, 16);
BufferLen := Offset;
end;
// --------------------------------------------------------------------------
//
// --------------------------------------------------------------------------
class procedure TDnsProtocolUtility.BuildPositiveHttpsResponsePacket(const DomainName: String; QueryType: Word; Buffer: Pointer; var BufferLen: Integer);
var
Offset: Integer;
begin
PByteArray(Buffer)^[$00] := $00;
PByteArray(Buffer)^[$01] := $00;
PByteArray(Buffer)^[$02] := $85;
PByteArray(Buffer)^[$03] := $80;
PByteArray(Buffer)^[$04] := $00;
PByteArray(Buffer)^[$05] := $01;
PByteArray(Buffer)^[$06] := $00;
PByteArray(Buffer)^[$07] := $00;
PByteArray(Buffer)^[$08] := $00;
PByteArray(Buffer)^[$09] := $00;
PByteArray(Buffer)^[$0A] := $00;
PByteArray(Buffer)^[$0B] := $00;
Offset := $0C;
TDnsProtocolUtility.SetStringIntoPacket(DomainName, Buffer, Offset, BufferLen);
PByteArray(Buffer)^[Offset] := QueryType shr $08; Inc(Offset);
PByteArray(Buffer)^[Offset] := QueryType and $FF; Inc(Offset);
PByteArray(Buffer)^[Offset] := $00; Inc(Offset);
PByteArray(Buffer)^[Offset] := $01; Inc(Offset);
BufferLen := Offset;
end;
// --------------------------------------------------------------------------
//
// --------------------------------------------------------------------------
class function TDnsProtocolUtility.PrintGenericPacketBytesAsStringFromPacket(Buffer: Pointer; BufferLen: Integer): String;
var
Index: Integer;
begin
Result := 'Z='; for Index := 0 to BufferLen - 1 do Result := Result + CommonUtils.ByteToHex2[PByteArray(Buffer)^[Index]];
end;
// --------------------------------------------------------------------------
//
// --------------------------------------------------------------------------
class function TDnsProtocolUtility.PrintGenericPacketBytesAsStringFromPacketWithOffset(Buffer: Pointer; BufferLen: Integer; Offset: Integer; NumBytes: Integer): String;
var
Index: Integer;
begin
SetLength(Result, 0); for Index := Offset to Min(BufferLen - 1, Offset + NumBytes - 1) do Result := Result + CommonUtils.ByteToHex2[PByteArray(Buffer)^[Index]];
end;
// --------------------------------------------------------------------------
//
// --------------------------------------------------------------------------
class function TDnsProtocolUtility.PrintRequestPacketDescriptionAsStringFromPacket(const DomainName: String; QueryType: Word; Buffer: Pointer; BufferLen: Integer; IncludePacketBytesAlways: Boolean): String;
var
OC: Byte; RD: Byte; QDC: Word;
begin
OC := (PByteArray(Buffer)^[$02] shr 3) and $0F;
RD := PByteArray(Buffer)^[$02] and $01;
QDC := TDnsProtocolUtility.GetWordFromPacket(Buffer, $04, BufferLen);
if IncludePacketBytesAlways then Result := 'OC=' + IntToStr(OC) + ';RD=' + IntToStr(RD) + ';QDC=' + IntToStr(QDC) + ';Q[1]=' + DomainName + ';T[1]=' + TDnsProtocolUtility.DnsQueryTypeToString(QueryType) + ';' + TDnsProtocolUtility.PrintGenericPacketBytesAsStringFromPacket(Buffer, BufferLen) else Result := 'Q[1]=' + DomainName + ';T[1]=' + TDnsProtocolUtility.DnsQueryTypeToString(QueryType);
end;
// --------------------------------------------------------------------------
//
// --------------------------------------------------------------------------
class function TDnsProtocolUtility.PrintResponsePacketDescriptionAsStringFromPacket(Buffer: Pointer; BufferLen: Integer; IncludePacketBytesAlways: Boolean): String;
var
OC: Byte; RC: Byte; TC: Byte; RD: Byte; RA: Byte; AA: Byte; QDC: Word; ANC: Word; NSC: Word; ARC: Word; FValue: String; AValue: String; BValue: String; OffsetL1: Integer; Index: Integer; AnTyp: Word; AnDta: Word;
begin
OC := (PByteArray(Buffer)^[$02] shr 3) and $0F;
RC := PByteArray(Buffer)^[$03] and $0F;
TC := (PByteArray(Buffer)^[$02] shr 1) and $01;
RD := PByteArray(Buffer)^[$02] and $01;
RA := (PByteArray(Buffer)^[$03] shr 7) and $01;
AA := (PByteArray(Buffer)^[$02] shr 2) and $01;
QDC := TDnsProtocolUtility.GetWordFromPacket(Buffer, $04, BufferLen);
ANC := TDnsProtocolUtility.GetWordFromPacket(Buffer, $06, BufferLen);
NSC := TDnsProtocolUtility.GetWordFromPacket(Buffer, $08, BufferLen);
ARC := TDnsProtocolUtility.GetWordFromPacket(Buffer, $0A, BufferLen);
FValue := 'OC=' + IntToStr(OC) + ';RC=' + IntToStr(RC) + ';TC=' + IntToStr(TC) + ';RD=' + IntToStr(RD) + ';RA=' + IntToStr(RA) + ';AA=' + IntToStr(AA) + ';QDC=' + IntToStr(QDC) + ';ANC=' + IntToStr(ANC) + ';NSC=' + IntToStr(NSC) + ';ARC=' + IntToStr(ARC);
if (RC = 0) and (TC = 0) and (QDC = 1) and ((ANC + NSC + ARC) > 0) then begin // We are only able to understand this
OffsetL1 := $0C; AValue := TDnsProtocolUtility.GetStringFromPacket(Buffer, OffsetL1, BufferLen); Inc(OffsetL1, 4);
FValue := FValue + ';' + 'Q[1]=' + AValue;
for Index := 1 to (ANC + NSC + ARC) do begin
if (OffsetL1 < BufferLen) then begin
AValue := TDnsProtocolUtility.GetStringFromPacket(Buffer, OffsetL1, BufferLen);
if ((OffsetL1 + 10) <= BufferLen) then begin
AnTyp := TDnsProtocolUtility.GetWordFromPacket(Buffer, OffsetL1, BufferLen); Inc(OffsetL1, 8);
AnDta := TDnsProtocolUtility.GetWordFromPacket(Buffer, OffsetL1, BufferLen); Inc(OffsetL1, 2);
FValue := FValue + ';T[' + IntToStr(Index) + ']=' + TDnsProtocolUtility.DnsQueryTypeToString(AnTyp);
if (AnDta > 0) then begin
if ((OffsetL1 + AnDta) <= BufferLen) then begin
case AnTyp of
DNS_QUERY_TYPE_A:
if (AnDta = 4) then begin
BValue := TIPv4AddressUtility.ToString(TDnsProtocolUtility.GetIPv4AddressFromPacket(Buffer, OffsetL1, BufferLen));
FValue := FValue + ';A[' + IntToStr(Index) + ']=' + AValue + '>' + BValue;
Inc(OffsetL1, AnDta);
end else begin
FValue := FValue + ';A[' + IntToStr(Index) + ']=' + AValue + '>' + TDnsProtocolUtility.PrintGenericPacketBytesAsStringFromPacketWithOffset(Buffer, BufferLen, OffsetL1, AnDta);
Inc(OffsetL1, AnDta);
end;
DNS_QUERY_TYPE_AAAA:
if (AnDta = 16) then begin
BValue := TIPv6AddressUtility.ToString(TDnsProtocolUtility.GetIPv6AddressFromPacket(Buffer, OffsetL1, BufferLen));
FValue := FValue + ';A[' + IntToStr(Index) + ']=' + AValue + '>' + BValue;
Inc(OffsetL1, AnDta);
end else begin
FValue := FValue + ';A[' + IntToStr(Index) + ']=' + AValue + '>' + TDnsProtocolUtility.PrintGenericPacketBytesAsStringFromPacketWithOffset(Buffer, BufferLen, OffsetL1, AnDta);
Inc(OffsetL1, AnDta);
end;
DNS_QUERY_TYPE_CNAME,
DNS_QUERY_TYPE_PTR:
begin
BValue := TDnsProtocolUtility.GetStringFromPacket(Buffer, OffsetL1, BufferLen);
FValue := FValue + ';A[' + IntToStr(Index) + ']=' + AValue + '>' + BValue;
end;
else begin
FValue := FValue + ';A[' + IntToStr(Index) + ']=' + AValue + '>' + TDnsProtocolUtility.PrintGenericPacketBytesAsStringFromPacketWithOffset(Buffer, BufferLen, OffsetL1, AnDta);
Inc(OffsetL1, AnDta);
end;
end;
end else begin
FValue := FValue + ';A[' + IntToStr(Index) + ']=' + AValue + '>NULL';
Break;
end;
end else begin
FValue := FValue + ';A[' + IntToStr(Index) + ']=' + AValue + '>NULL';
end;
end else begin
Break;
end;
end else begin
Break;
end;
end;
if IncludePacketBytesAlways then Result := FValue + ';' + TDnsProtocolUtility.PrintGenericPacketBytesAsStringFromPacket(Buffer, BufferLen) else Result := FValue;
end else begin
Result := FValue + ';' + TDnsProtocolUtility.PrintGenericPacketBytesAsStringFromPacket(Buffer, BufferLen);
end;
end;
// --------------------------------------------------------------------------
//
// --------------------------------------------------------------------------
class function TDnsProtocolUtility.IsValidRequestPacket(Buffer: Pointer; BufferLen: Integer): Boolean;
var
QR: Byte;
begin
QR := (PByteArray(Buffer)^[$02] shr 7) and $01; Result := (QR = 0);
end;
// --------------------------------------------------------------------------
//
// --------------------------------------------------------------------------
class function TDnsProtocolUtility.IsValidResponsePacket(Buffer: Pointer; BufferLen: Integer): Boolean;
var
QR: Byte;
begin
QR := (PByteArray(Buffer)^[$02] shr 7) and $01; Result := (QR = 1);
end;
// --------------------------------------------------------------------------
//
// --------------------------------------------------------------------------
class function TDnsProtocolUtility.IsFailureResponsePacket(Buffer: Pointer; BufferLen: Integer): Boolean;
var
RC: Byte;
begin
RC := PByteArray(Buffer)^[$03] and $0F; Result := not((RC = 0) or (RC = 3));
end;
// --------------------------------------------------------------------------
//
// --------------------------------------------------------------------------
class function TDnsProtocolUtility.IsNegativeResponsePacket(Buffer: Pointer; BufferLen: Integer): Boolean;
var
RC: Byte;
begin
RC := PByteArray(Buffer)^[$03] and $0F; Result := (RC = 3);
end;
// --------------------------------------------------------------------------
//
// --------------------------------------------------------------------------
class function TDnsProtocolUtility.IsTruncatedResponsePacket(Buffer: Pointer; BufferLen: Integer): Boolean;
begin
Result := (PByteArray(Buffer)^[$02] and $02) > 0;
end;
// --------------------------------------------------------------------------
//
// --------------------------------------------------------------------------
end.