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IdDNSoverHTTPSResolver.pas
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IdDNSoverHTTPSResolver.pas
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// chuacw, Singapore
unit IdDNSoverHTTPSResolver;
interface
uses
IdDNSResolver, IdDNSCommon, IdHTTP, IdGlobal, IdURI;
type
TIdDoHResolver = class(TIdDNSResolver)
protected
// Fot bootstrapping only!
FURI: TIdURI;
FQueryURL, FBootstrapAddress: string;
FHTTP: TIdHTTP;
FSSLIOHandler: TObject;
FPreventAttacks,
FEnablePrivacy, FDisableValidation, FDNSSecOk: Boolean;
FQueryValues: TArray<Integer>;
FQueryStrings: TArray<string>;
procedure SetQueryURL(const Value: string);
protected
procedure InitComponent; override;
/// <summary> Provides opportunity to update the URL before sending it to the
/// DNS resolver, so descendants can set additional parameters on the URL</summary>
procedure UpdateURL(var VURL: string); virtual;
/// <summary> Allows descendants to update the HTTP.Request.Accept string. </summary>
procedure UpdateAccept; virtual;
class function ParseJSONResponse(const AResponse: string; const ID: UInt16; AQueryClass: UInt16): TIdBytes; static;
public
destructor Destroy; override;
procedure Resolve(const ADomainName: string; SOARR : TIdRR_SOA = nil; QClass: integer = Class_IN);
procedure AddQueryType(const AQueryType: NativeUInt); overload;
procedure AddQueryType(const AQueryType: string); overload;
property BootstrapAddress: string read FBootstrapAddress write FBootstrapAddress;
property QueryURL: string read FQueryURL write SetQueryURL;
property DNSSecOk: Boolean read FDNSSecOk write FDNSSecOk;
property DisableValidation: Boolean read FDisableValidation write FDisableValidation;
property EnablePrivacy: Boolean read FEnablePrivacy write FEnablePrivacy;
property PreventAttacks: Boolean read FPreventAttacks write FPreventAttacks;
end;
TDoHResolverClass = class of TIdDoHResolver;
implementation
uses
System.JSON, IdStack, System.StrUtils, System.SysUtils, InternetDateUtils,
System.DateUtils, IdGlobalProtocols, IdSSLOpenSSL, IdExceptionCore;
type
TIdHTTPKeepAliveResponse = class(TIdHTTP)
private
FHTTPProto: TIdHTTPProtocol;
protected
function CreateProtocol: TIdHTTPProtocol; override;
procedure InitComponent; override;
property HTTPProto: TIdHTTPProtocol read FHTTPProto;
end;
function TIdHTTPKeepAliveResponse.CreateProtocol: TIdHTTPProtocol;
begin
Result := inherited;
Result.Response.KeepAlive := True;
end;
procedure TIdHTTPKeepAliveResponse.InitComponent;
begin
inherited;
ProtocolVersion := pv1_1;
end;
// See https://developers.cloudflare.com/1.1.1.1/dns-over-https/json-format/
{ TIdDoHResolver }
procedure TIdDoHResolver.AddQueryType(const AQueryType: NativeUInt);
begin
FQueryValues := FQueryValues + [AQueryType];
end;
procedure TIdDoHResolver.AddQueryType(const AQueryType: string);
begin
FQueryStrings := FQueryStrings + [AQueryType];
end;
destructor TIdDoHResolver.Destroy;
begin
FURI.Free;
FSSLIOHandler.Free;
FHTTP.Free;
inherited;
end;
procedure TIdDoHResolver.InitComponent;
begin
inherited;
FBootstrapAddress := '1.1.1.1'; // Cloudflare
end;
function LengthToBytes(const ALength: Integer): TIdBytes;
begin
if ALength < High(Byte) then
Result := ToBytes(UInt8(ALength)) else
if ALength < High(UInt16) then
Result := ToBytes(UInt16(ALength)) else
if ALength < High(Integer) then
Result := ToBytes(UInt32(ALength));
end;
class function TIdDoHResolver.ParseJSONResponse(const AResponse: string; const ID: UInt16; AQueryClass: UInt16): TIdBytes;
const
TypeCode_RRSIG = 46;
CTypeCodes: array[TQueryRecordTypes] of UInt16 = (
TypeCode_A,
TypeCode_NS,
TypeCode_MD,
TypeCode_MF,
TypeCode_CName,
TypeCode_SOA,
TypeCode_MB,
TypeCode_MG,
TypeCode_MR,
TypeCode_NULL,
TypeCode_WKS,
TypeCode_PTR,
TypeCode_HINFO,
TypeCode_MINFO,
TypeCode_MX,
TypeCode_TXT,
// TypeCode_RP, TypeCode_AFSDB, TypeCode_X25, TypeCode_ISDN,
TypeCode_RT, TypeCode_NSAP, TypeCode_NSAP_PTR, TypeCode_SIG,
// TypeCode_KEY, TypeCode_PX, TypeCode_QPOS,
TypeCode_AAAA,
// TypeCode_LOC, TypeCode_NXT, TypeCode_R31, TypeCode_R32,
TypeCode_Service,
// TypeCode_R34,
TypeCode_NAPTR,
// TypeCode_KX,
TypeCode_CERT,
TypeCode_V6Addr,
TypeCode_DNAME,
TypeCode_R40,
TypeCode_OPTIONAL,
TypeCode_IXFR,
TypeCode_AXFR,
TypeCode_STAR
// TypeCode_Error
);
var
LJSONObj, LQuestionObj, LAnswerObj: TJSONObject;
BitCode, QDCount, ANCount, NSCount, ARCount: UInt16;
LQuestions, LAnswers, LAuthority, LAdditional: TJSONArray;
LMX, LSOA, LRRSIG: TArray<string>;
LMName, LRName, LDomainName: string; LNameValue: string; LDataValue: string;
LSOASerial, LSOARefresh, LSOARetry, LSOAExpire, LSOAMinimumTTL: UInt32;
RD_Length, LTypeValue: UInt16; LClassValue: Word;
LTTLValue: UInt32;
LData, RData: TIdBytes;
I, J: UInt16;
LStatus: Word;
/// <summary>Truncated bit was set </summary>
TC,
/// <summary>Recursive Desired bit was set </summary>
RD,
/// <summary>Recursion available bit was set </summary>
RA,
/// <summary> Answer verified with DNSSEC </summary>
AD,
/// <summary> if true, client has asked to disable DNSSEC validation </summary>
CD: Boolean;
VAddress: TIdIPv6Address;
begin
Result := nil;
LJSONObj := TJSONObject.ParseJSONValue(AResponse) as TJSONObject;
try
LJSONObj.TryGetValue<UInt16>('Status', LStatus);
LJSONObj.TryGetValue<Boolean>('TC', TC);
LJSONObj.TryGetValue<Boolean>('RD', RD);
LJSONObj.TryGetValue<Boolean>('RA', RA);
LJSONObj.TryGetValue<Boolean>('AD', AD);
LJSONObj.TryGetValue<Boolean>('CD', CD);
BitCode := 0; QDCount := 0; ANCount := 0; NSCount := 0; ARCount := 0;
if LJSONObj.TryGetValue('Question', LQuestions) then
QDCount := LQuestions.Count;
if LJSONObj.TryGetValue('Answer', LAnswers) then
ANCount := LAnswers.Count;
if LJSONObj.TryGetValue('Authority', LAuthority) then
NSCount := LAuthority.Count;
if LJSONObj.TryGetValue('Additional', LAdditional) then
ARCount := LAdditional.Count;
Result := ToBytes(GStack.HostToNetwork(ID)) +
ToBytes(GStack.HostToNetwork(BitCode)) +
ToBytes(GStack.HostToNetwork(QDCount)) +
ToBytes(GStack.HostToNetwork(ANCount)) +
ToBytes(GStack.HostToNetwork(NSCount)) +
ToBytes(GStack.HostToNetwork(ARCount));
if QDCount > 0 then
begin
for I := 0 to QDCount-1 do
begin
LQuestionObj := LQuestions.Items[I] as TJSONObject;
LDomainName := LQuestionObj.GetValue<string>('name');
LTypeValue := LQuestionObj.GetValue<UInt16>('type');
Result := Result + DomainNameToDNSStr(LDomainName) +
ToBytes(GStack.HostToNetwork(LTypeValue)) +
ToBytes(GStack.HostToNetwork(UInt16(AQueryClass))); // 0 as class
end;
end;
if ANCount > 0 then
begin
for I := 0 to ANCount-1 do
begin
RData := nil;
LAnswerObj := LAnswers.Items[I] as TJSONObject;
LNameValue := LAnswerObj.GetValue<string>('name');
LTypeValue := LAnswerObj.GetValue<UInt16>('type');
// Class? What value?
LClassValue := 0;
LTTLValue := LAnswerObj.GetValue<UInt32>('TTL');
LDataValue := LAnswerObj.GetValue<string>('data'); // IP address
case LTypeValue of
TypeCode_SOA: begin
LSOA := TArray<string>(SplitString(LDataValue, ' '));
LMName := LSOA[0];
LRName := LSOA[1];
LSOASerial := StrToUInt(LSOA[2]);
LSOARefresh := StrToUInt(LSOA[3]);
LSOARetry := StrToUInt(LSOA[4]);
LSOAExpire := StrToUIntDef(LSOA[5], 0);
if LSOAExpire = 0 then
begin
var LSOAExpireDT: TDateTime := 0;
if TryRFC1123ToDateTime(LSOA[5], LSOAExpireDT) then
begin
var MSecsSince1970 := MilliSecondsBetween(LSOAExpireDT, EncodeDate(1970, 1, 1));
LSOAExpire := MSecsSince1970;
end;
end;
LSOAMinimumTTL := StrToUInt(LSOA[6]);
RData := DomainNameToDNSStr(LMName) + DomainNameToDNSStr(LRName) +
ToBytes(GStack.HostToNetwork(LSOASerial)) +
ToBytes(GStack.HostToNetwork(LSOARefresh)) +
ToBytes(GStack.HostToNetwork(LSOARetry)) +
ToBytes(GStack.HostToNetwork(LSOAExpire)) +
ToBytes(GStack.HostToNetwork(LSOAMinimumTTL));
end;
TypeCode_TXT: begin
RData := NormalStrToDNSStr(LDataValue) + [0];
end;
TypeCode_NAPTR: begin
var LOrder: UInt16 := 11;
var LPref: UInt16 := 22;
var LFlags: string := 'FLAG';
var LService: string := 'Service';
var LRegExp: string := 'REGEXP';
var LReplacement: string := 'REPLACE';
RData := ToBytes(GStack.NetworkToHost(LOrder)) +
ToBytes(GStack.NetworkToHost(LPref)) +
NormalStrToDNSStr(LFlags) +
NormalStrToDNSStr(LService) +
NormalStrToDNSStr(LRegExp) +
NormalStrToDNSStr(LReplacement);
end;
TypeCode_HINFO: begin
var LCPU := NormalStrToDNSStr('AMD');
var LOS := NormalStrToDNSStr('Windows');
RData := LCPU + LOS + [0];
end;
TypeCode_A: begin
// FIPAddress := MakeUInt32IntoIPv4Address(GStack.NetworkToHost(OrdFourByteToUInt32(RData[0], RData[1], RData[2], RData[3])));
if IsValidIP(LDataValue) then
RData := ToBytes(GStack.HostToNetwork(IPv4ToUInt32(LDataValue)));
end;
TypeCode_NS,
TypeCode_CName: begin
RData := DomainNameToDNSStr(LDataValue);
end;
TypeCode_MX: begin
LMX := SplitString(LDataValue, ' ');
var LPreference: UInt16 := StrToUInt(LMX[0]);
var LExchangeServer := LMX[1];
RData := ToBytes(GStack.HostToNetwork(LPreference)) +
DomainNameToDNSStr(LExchangeServer);
end;
TypeCode_AAAA: begin
if IsValidIP(LDataValue) and (Length(LDataValue)>15) then
begin
IPv6ToIdIPv6Address(LDataValue, VAddress);
RData := nil;
for J := 0 to 7 do
RData := RData + ToBytes(GStack.HostToNetwork(VAddress[J]));
end;
end;
TypeCode_RRSIG: begin // RRSIG
// "Expires": "Wed, 12 Jun 2019 06:32:03 UTC",
// "data": "SOA 8 2 3600 20190622141844 20190601215824 23689 example.com. cbLvbWFP1gPLnXTLMZOwzynw9dd0hrojJcw0Xody31u+zqXPLxclFsswKzUu972875Hzyo18jYFeQ52gwQ0voRT15HUfDiBtfR/sXJl0AgNoBiF3zo12ehzS/rvDZNDoRQjNFsBcCJnKSg+tqWft3xA/s8g1TUCSjnfULql/Ykk="
// RRSIG for example.com
// "data": "nsec 8 2 3600 1561200044 1559390304 23689 example.com. hBT2zBFJlU5EUkdSfNwtueAWnMa7/BmkCGHDypBxmR5po5huPFQppIr87N7pbfhVHrhDxoZMktALYilVuCo0yeJY0ZwQZWw8XiIccuQorrhvIj4bywQ/7ol0F033CUpGAZb3JxzfdKh9CDY1Ma+0/qadYH1xSU18juYH3G/2GHw="
var LExpiresDT: string; var LExpiresUInt: UInt32 := 0;
var LExpires: TDateTime := 0;
if LAnswerObj.TryGetValue<string>('Expires', LExpiresDT) then
TryRFC1123ToDateTime(LExpiresDT, LExpires);
LRRSIG := SplitString(LDataValue, ' ');
var LDNSTypeCovered := LRRSIG[0]; // nsec
var LAlgorithmCovered := LRRSIG[1]; // 8
var LNumOfLabels := LRRSIG[2]; // 2
var LOriginalTTL := LRRSIG[3]; // 3600
var LSignatureExpiration := LRRSIG[4]; // 1561200044
var LSignatureInception := LRRSIG[5]; // 1559390304
var LKeyTag := LRRSIG[6]; // 23689
var LSignerName := LRRSIG[7]; // example.com
var LSignature := LRRSIG[8]; // hBT2zBFJlU5EUk....
RData := [0];
// RData := NormalStrToDNSStr(LMName) + NormalStrToDNSStr(LRName) +
// ToBytes(GStack.HostToNetwork(LSOASerial)) +
// ToBytes(GStack.HostToNetwork(LSOARefresh)) +
// ToBytes(GStack.HostToNetwork(LSOARetry)) +
// ToBytes(GStack.HostToNetwork(LSOAExpire)) +
// ToBytes(GStack.HostToNetwork(LSOAMinimumTTL));
//
// RD_Length := Length(RData);
end;
else
raise Exception.Create('Unhandled type!');
end;
RD_Length := Length(RData);
Result := Result + DomainNameToDNSStr(LNameValue) +
ToBytes(GStack.HostToNetwork(LTypeValue)) +
ToBytes(GStack.HostToNetwork(LClassValue)) +
ToBytes(GStack.HostToNetwork(LTTLValue)) +
ToBytes(GStack.HostToNetwork(RD_Length)) + RData;
end;
end;
if NSCount > 0 then
begin
for I := 0 to NSCount-1 do
begin
RData := nil;
LAnswerObj := LAuthority.Items[I] as TJSONObject;
LNameValue := LAnswerObj.GetValue<string>('name');
LTypeValue := LAnswerObj.GetValue<UInt16>('type');
// Class? What value?
LClassValue := 0;
LTTLValue := LAnswerObj.GetValue<UInt32>('TTL');
LDataValue := LAnswerObj.GetValue<string>('data');
// "jule.ns.cloudflare.com. dns.cloudflare.com. 2031180241 10000 2400 604800 3600"
// MNAME RNAME Serial Refresh Retry Expire MinimumTTL
case LTypeValue of
TypeCode_SOA: begin
LSOA := SplitString(LDataValue, ' ');
LMName := LSOA[0];
LRName := LSOA[1];
LSOASerial := StrToUInt(LSOA[2]);
LSOARefresh := StrToUInt(LSOA[3]);
LSOARetry := StrToUInt(LSOA[4]);
LSOAExpire := StrToUIntDef(LSOA[5], 0);
if LSOAExpire = 0 then
begin
var LSOAExpireDT: TDateTime := 0;
if TryRFC1123ToDateTime(LSOA[5], LSOAExpireDT) then
begin
var MSecsSince1970 := MilliSecondsBetween(LSOAExpireDT, EncodeDate(1970, 1, 1));
LSOAExpire := MSecsSince1970;
end;
end;
LSOAMinimumTTL := StrToUInt(LSOA[6]);
RData := DomainNameToDNSStr(LMName) + DomainNameToDNSStr(LRName) +
ToBytes(GStack.HostToNetwork(LSOASerial)) +
ToBytes(GStack.HostToNetwork(LSOARefresh)) +
ToBytes(GStack.HostToNetwork(LSOARetry)) +
ToBytes(GStack.HostToNetwork(LSOAExpire)) +
ToBytes(GStack.HostToNetwork(LSOAMinimumTTL));
end;
TypeCode_RRSIG: begin // RRSIG
// "Expires": "Wed, 12 Jun 2019 06:32:03 UTC",
// "data": "SOA 8 2 3600 20190622141844 20190601215824 23689 example.com. cbLvbWFP1gPLnXTLMZOwzynw9dd0hrojJcw0Xody31u+zqXPLxclFsswKzUu972875Hzyo18jYFeQ52gwQ0voRT15HUfDiBtfR/sXJl0AgNoBiF3zo12ehzS/rvDZNDoRQjNFsBcCJnKSg+tqWft3xA/s8g1TUCSjnfULql/Ykk="
var LExpiresDT: string; var LExpiresUInt: UInt32 := 0;
var LExpires: TDateTime := 0;
if LAnswerObj.TryGetValue<string>('Expires', LExpiresDT) then
TryRFC1123ToDateTime(LExpiresDT, LExpires);
LSOA := SplitString(LDataValue, ' ');
LSOASerial := 0;
LSOARefresh := 0;
LSOARetry := 0;
LSOAExpire := 0;
LSOAMinimumTTL := 0;
LMName := ''; LRName := '';
RData := NormalStrToDNSStr(LMName) + NormalStrToDNSStr(LRName) +
ToBytes(GStack.HostToNetwork(LSOASerial)) +
ToBytes(GStack.HostToNetwork(LSOARefresh)) +
ToBytes(GStack.HostToNetwork(LSOARetry)) +
ToBytes(GStack.HostToNetwork(LSOAExpire)) +
ToBytes(GStack.HostToNetwork(LSOAMinimumTTL));
end;
47: begin
// "Expires": "Wed, 12 Jun 2019 06:32:03 UTC",
// "data": "www.example.com. A NS SOA TXT AAAA RRSIG NSEC DNSKEY"
var LExpiresDT: string; var LExpiresUInt: UInt32 := 0;
var LExpires: TDateTime := 0;
if LAnswerObj.TryGetValue<string>('Expires', LExpiresDT) then
TryRFC1123ToDateTime(LExpiresDT, LExpires);
LDataValue := LAnswerObj.GetValue<string>('data');
LSOASerial := 0;
LSOARefresh := 0;
LSOARetry := 0;
LSOAExpire := 0;
LSOAMinimumTTL := 0;
LMName := ''; LRName := '';
RData := NormalStrToDNSStr(LMName) + NormalStrToDNSStr(LRName) +
ToBytes(GStack.HostToNetwork(LSOASerial)) +
ToBytes(GStack.HostToNetwork(LSOARefresh)) +
ToBytes(GStack.HostToNetwork(LSOARetry)) +
ToBytes(GStack.HostToNetwork(LSOAExpire)) +
ToBytes(GStack.HostToNetwork(LSOAMinimumTTL));
end;
else
raise Exception.Create('Unhandled type!');
end;
RD_Length := Length(RData);
Result := Result + DomainNameToDNSStr(LNameValue) +
ToBytes(GStack.HostToNetwork(LTypeValue)) +
ToBytes(GStack.HostToNetwork(LClassValue)) +
ToBytes(GStack.HostToNetwork(LTTLValue)) +
ToBytes(GStack.HostToNetwork(RD_Length)) +
RData;
end;
end;
if ARCount > 0 then
begin
for I := 0 to NSCount-1 do
begin
end;
end;
finally
LJSONObj.Free;
end;
end;
procedure TIdDoHResolver.Resolve(const ADomainName: string; SOARR: TIdRR_SOA;
QClass: integer);
const
CQueryTypes: array[qtA..qtSTAR] of string = (
'A',
'NS',
'MD',
'MF',
'Name',
'SOA',
'MB',
'MG',
'MR',
'NULL',
'WKS',
'PTR',
'HINFO',
'MINFO',
'MX',
'TXT',
'RT',
'NSAP',
'NSAP_PTR',
'SIG',
'AAAA',
'SRV',
'NAPTR',
'CERT',
'V6Addr',
'DName',
'R40',
'Optional',
'IXFR',
'AXFR',
'STAR'
);
var
LSucceeded: Boolean;
LTryCount: Integer;
LURL,
LType, LResponse: string;
LQueryType: TQueryRecordTypes;
LSSLIOHandler: TIdSSLIOHandlerSocketOpenSSL;
LDNSResponse: TIdBytes;
begin
if not Assigned(FHTTP) then
begin
FHTTP := TIdHTTPKeepAliveResponse.Create(Self);
end;
if not Assigned(FSSLIOHandler) then
begin
LSSLIOHandler := TIdSSLIOHandlerSocketOpenSSL.Create(FHTTP);
LSSLIOHandler.SSLOptions.Method := sslvSSLv23;
LSSLIOHandler.SSLOptions.VerifyMode := [];
LSSLIOHandler.SSLOptions.VerifyDepth := 2;
FSSLIOHandler := LSSLIOHandler;
FHTTP.IOHandler := LSSLIOHandler;
end;
LTryCount := 0; LSucceeded := False;
repeat
LResponse := ''; LType := '';
UpdateAccept;
FHTTP.HTTPOptions := FHTTP.HTTPOptions + [hoKeepOrigProtocol];
FHTTP.Request.Connection := 'keep-alive';
if TIdHTTPKeepAliveResponse(FHTTP).HTTPProto <> nil then
TIdHTTPKeepAliveResponse(FHTTP).HTTPProto.Response.KeepAlive := True;
if QueryType <> [] then
begin
for LQueryType in QueryType do
begin
if LQueryType < High(TQueryRecordTypes) then
LType := Format('%s&type=%s', [LType, CQueryTypes[LQueryType]]) else
LType := Format('%s&type=%d', [LType, Ord(LQueryType)]);
end;
end else
if FQueryValues <> nil then
begin
for var LQueryValue in FQueryValues do
begin
LType := Format('%s&type=%d', [LType, LQueryValue]);
end;
FQueryValues := nil;
end else
if FQueryStrings <> nil then
begin
for var LQueryValue in FQueryStrings do
begin
LType := Format('%s&type=%s', [LType, LQueryValue]);
end;
FQueryStrings := nil;
end;
if LType = '' then
raise EIdDnsResolverError.Create('Need to specify QueryType!');
LURL := Format('%s?name=%s%s', [FQueryURL, ADomainName, LType]);
UpdateURL(LURL);
try
Inc(LTryCount);
LResponse := FHTTP.Get(LURL);
if LResponse <> '' then
begin
LDNSResponse := ParseJSONResponse(LResponse, FDNSHeader.ID, QClass);
if Length(LDNSResponse) > 4 then
FillResult(LDNSResponse);
end;
LSucceeded := True;
except
on E: Exception do // failed to load SSL library or some other thingy?
end;
until (LTryCount>3) or (LSucceeded);
end;
procedure TIdDoHResolver.SetQueryURL(const Value: string);
var
LURL: string;
begin
if not Value.StartsWith('http') then
LURL := 'https://' + Value else
LURL := Value;
FQueryURL := LURL;
if BootstrapAddress = '' then
Exit;
// Try bootstrapping silently...
try
if not Assigned(FURI) then
FURI := TIdURI.Create(FQueryURL) else
FURI.URI := FQueryURL;
if not GStack.IsIP(FURI.Host) then
begin
QueryResult.Clear;
inherited Host := BootstrapAddress;
QueryType := [qtA];
var LHostName := FURI.Host;
inherited Resolve(LHostName);
if QueryResult.Count > 0 then
begin
for var I := 0 to QueryResult.Count-1 do
if QueryResult[I] is TARecord then
begin
var LARecord := TARecord(QueryResult[I]);
FURI.Host := LARecord.IPAddress;
FQueryURL := FURI.URI;
Break;
end;
end;
end;
except
// keep quiet about failure to bootstrap
end;
end;
procedure TIdDoHResolver.UpdateAccept;
begin
FHTTP.Request.Accept := 'application/dns+json';
end;
procedure TIdDoHResolver.UpdateURL(var VURL: string);
begin
end;
end.