public static List <NameServerAddress> GetNameServersFromResponse(DnsDatagram response, bool preferIPv6, bool selectOnlyNameServersWithGlue)
{
List <NameServerAddress> nameServers = new List <NameServerAddress>(response.Authority.Count);
foreach (DnsResourceRecord authorityRecord in response.Authority)
{
if (authorityRecord.Type == DnsResourceRecordType.NS)
{
DnsNSRecord nsRecord = (DnsNSRecord)authorityRecord.RDATA;
IPEndPoint endPoint = null;
//find ip address of authoritative name server from additional records
foreach (DnsResourceRecord rr in response.Additional)
{
if (nsRecord.NameServer.Equals(rr.Name, StringComparison.OrdinalIgnoreCase))
{
switch (rr.Type)
{
case DnsResourceRecordType.A:
endPoint = new IPEndPoint(((DnsARecord)rr.RDATA).Address, 53);
nameServers.Add(new NameServerAddress(nsRecord.NameServer, endPoint));
break;
case DnsResourceRecordType.AAAA:
endPoint = new IPEndPoint(((DnsAAAARecord)rr.RDATA).Address, 53);
if (preferIPv6)
{
nameServers.Add(new NameServerAddress(nsRecord.NameServer, endPoint));
}
break;
}
}
}
if ((endPoint == null) && !selectOnlyNameServersWithGlue)
{
nameServers.Add(new NameServerAddress(new DomainEndPoint(nsRecord.NameServer, 53)));
}
}
}
return(nameServers);
}
internal DnsDatagram Clone(IReadOnlyList <DnsResourceRecord> answer, IReadOnlyList <DnsResourceRecord> authority)
{
if (answer == null)
{
answer = _answer;
}
if (authority == null)
{
authority = _authority;
}
DnsDatagram datagram = new DnsDatagram(_ID, _QR == 1, _OPCODE, _AA == 1, _TC == 1, _RD == 1, _RA == 1, _AD == 1, _CD == 1, _RCODE, _question, answer, authority, _additional);
datagram._metadata = _metadata;
return(datagram);
}
public void WriteTo(Stream s, List <DnsDomainOffset> domainEntries)
{
long originalPosition = s.Position;
//write dummy RDLENGTH
s.Position += 2;
//write RDATA
WriteRecordData(s, domainEntries);
long finalPosition = s.Position;
//write actual RDLENGTH
ushort length = Convert.ToUInt16(finalPosition - originalPosition - 2);
s.Position = originalPosition;
DnsDatagram.WriteUInt16NetworkOrder(length, s);
s.Position = finalPosition;
}
public string ResolvePTR(IPAddress ip)
{
DnsDatagram response = Resolve(new DnsQuestionRecord(ip, DnsClass.IN));
switch (response.Header.RCODE)
{
case DnsResponseCode.NoError:
if ((response.Header.ANCOUNT > 0) && (response.Answer[0].Type == DnsResourceRecordType.PTR))
{
return(((DnsPTRRecord)response.Answer[0].RDATA).PTRDomainName);
}
return(null);
case DnsResponseCode.NameError:
throw new NameErrorDnsClientException("PTR record does not exists for ip: " + ip.ToString() + "; Name server: " + response.NameServerAddress.ToString());
default:
throw new DnsClientException("Name server returned error. DNS RCODE: " + response.Header.RCODE.ToString() + " (" + response.Header.RCODE + ")");
}
}
public DnsQuestionRecord(Stream s)
{
_name = DnsDatagram.ConvertLabelToDomain(s);
_type = (DnsResourceRecordType)DnsDatagram.ReadUInt16NetworkOrder(s);
_class = (DnsClass)DnsDatagram.ReadUInt16NetworkOrder(s);
}
protected override void Parse(Stream s)
{
_ptrDomainName = DnsDatagram.DeserializeDomainName(s);
}
public DnsQuestionRecord(Stream s)
{
_name = DnsDatagram.DeserializeDomainName(s);
_type = (DnsResourceRecordType)DnsDatagram.ReadUInt16NetworkOrder(s);
_class = (DnsClass)DnsDatagram.ReadUInt16NetworkOrder(s);
}
public IPAddress[] ResolveIP(string domain, bool preferIPv6 = false)
{
int hopCount = 0;
DnsResourceRecordType type = preferIPv6 ? DnsResourceRecordType.AAAA : DnsResourceRecordType.A;
while ((hopCount++) < MAX_HOPS)
{
DnsDatagram response = Resolve(new DnsQuestionRecord(domain, type, DnsClass.IN));
switch (response.Header.RCODE)
{
case DnsResponseCode.NoError:
if (response.Header.ANCOUNT == 0)
{
if (type == DnsResourceRecordType.AAAA)
{
type = DnsResourceRecordType.A;
continue;
}
return(new IPAddress[] { });
}
List <IPAddress> ipAddresses = new List <IPAddress>();
foreach (DnsResourceRecord record in response.Answer)
{
if (record.Name.Equals(domain, StringComparison.CurrentCultureIgnoreCase))
{
switch (record.Type)
{
case DnsResourceRecordType.A:
ipAddresses.Add(((DnsARecord)record.RDATA).Address);
break;
case DnsResourceRecordType.AAAA:
ipAddresses.Add(((DnsAAAARecord)record.RDATA).Address);
break;
case DnsResourceRecordType.CNAME:
domain = ((DnsCNAMERecord)record.RDATA).CNAMEDomainName;
break;
default:
throw new DnsClientException("Name server [" + response.NameServerAddress.ToString() + "] returned unexpected record type [ " + record.Type.ToString() + "] for domain: " + domain);
}
}
}
if (ipAddresses.Count > 0)
{
return(ipAddresses.ToArray());
}
break;
case DnsResponseCode.NameError:
throw new NameErrorDnsClientException("Domain does not exists: " + domain + "; Name server: " + response.NameServerAddress.ToString());
default:
throw new DnsClientException("Name server returned error. DNS RCODE: " + response.Header.RCODE.ToString() + " (" + response.Header.RCODE + ")");
}
}
throw new DnsClientException("No answer received from name server for domain: " + domain);
}
public string[] ResolveMX(string domain, bool resolveIP = false, bool preferIPv6 = false)
{
if (IPAddress.TryParse(domain, out IPAddress parsedIP))
{
//host is valid ip address
return(new string[] { domain });
}
int hopCount = 0;
while ((hopCount++) < MAX_HOPS)
{
DnsDatagram response = Resolve(new DnsQuestionRecord(domain, DnsResourceRecordType.MX, DnsClass.IN));
switch (response.Header.RCODE)
{
case DnsResponseCode.NoError:
if (response.Header.ANCOUNT == 0)
{
return new string[] { }
}
;
List <DnsMXRecord> mxRecordsList = new List <DnsMXRecord>();
foreach (DnsResourceRecord record in response.Answer)
{
if (record.Name.Equals(domain, StringComparison.CurrentCultureIgnoreCase))
{
switch (record.Type)
{
case DnsResourceRecordType.MX:
mxRecordsList.Add((DnsMXRecord)record.RDATA);
break;
case DnsResourceRecordType.CNAME:
domain = ((DnsCNAMERecord)record.RDATA).CNAMEDomainName;
break;
default:
throw new DnsClientException("Name server [" + response.NameServerAddress.ToString() + "] returned unexpected record type [" + record.Type.ToString() + "] for domain: " + domain);
}
}
}
if (mxRecordsList.Count > 0)
{
DnsMXRecord[] mxRecords = mxRecordsList.ToArray();
//sort by mx preference
Array.Sort(mxRecords);
if (resolveIP)
{
List <string> mxEntries = new List <string>();
//check glue records
for (int i = 0; i < mxRecords.Length; i++)
{
string mxDomain = mxRecords[i].Exchange;
bool glueRecordFound = false;
foreach (DnsResourceRecord record in response.Additional)
{
if (record.Name.Equals(mxDomain, StringComparison.CurrentCultureIgnoreCase))
{
switch (record.Type)
{
case DnsResourceRecordType.A:
if (!preferIPv6)
{
mxEntries.Add(((DnsARecord)record.RDATA).Address.ToString());
glueRecordFound = true;
}
break;
case DnsResourceRecordType.AAAA:
if (preferIPv6)
{
mxEntries.Add(((DnsAAAARecord)record.RDATA).Address.ToString());
glueRecordFound = true;
}
break;
}
}
}
if (!glueRecordFound)
{
try
{
IPAddress[] ipList = ResolveIP(mxDomain, preferIPv6);
foreach (IPAddress ip in ipList)
{
mxEntries.Add(ip.ToString());
}
}
catch (NameErrorDnsClientException)
{ }
catch (DnsClientException)
{
mxEntries.Add(mxDomain);
}
}
}
return(mxEntries.ToArray());
}
else
{
string[] mxEntries = new string[mxRecords.Length];
for (int i = 0; i < mxRecords.Length; i++)
{
mxEntries[i] = mxRecords[i].Exchange;
}
return(mxEntries);
}
}
break;
case DnsResponseCode.NameError:
throw new NameErrorDnsClientException("Domain does not exists: " + domain + "; Name server: " + response.NameServerAddress.ToString());
default:
throw new DnsClientException("Name server returned error. DNS RCODE: " + response.Header.RCODE.ToString() + " (" + response.Header.RCODE + ")");
}
}
throw new DnsClientException("No answer received from name server for domain: " + domain);
}
public static DnsDatagram ResolveViaNameServers(DnsQuestionRecord question, NameServerAddress[] nameServers = null, IDnsCache cache = null, NetProxy proxy = null, bool preferIPv6 = false, bool tcp = false, int retries = 2, int maxStackCount = 10)
{
if ((nameServers != null) && (nameServers.Length > 0))
{
//create copy of name servers array so that the values in original array are not messed due to shuffling feature
NameServerAddress[] nameServersCopy = new NameServerAddress[nameServers.Length];
Array.Copy(nameServers, nameServersCopy, nameServers.Length);
nameServers = nameServersCopy;
}
Stack <ResolverData> resolverStack = new Stack <ResolverData>();
int stackNameServerIndex = 0;
while (true) //stack loop
{
if (resolverStack.Count > maxStackCount)
{
while (resolverStack.Count > 0)
{
ResolverData data = resolverStack.Pop();
question = data.Question;
}
throw new DnsClientException("DnsClient exceeded the maximum stack count to resolve the domain: " + question.Name);
}
if (cache != null)
{
DnsDatagram request = new DnsDatagram(new DnsHeader(0, false, DnsOpcode.StandardQuery, false, false, true, false, false, false, DnsResponseCode.NoError, 1, 0, 0, 0), new DnsQuestionRecord[] { question }, null, null, null);
DnsDatagram cacheResponse = cache.Query(request);
switch (cacheResponse.Header.RCODE)
{
case DnsResponseCode.NoError:
if (cacheResponse.Answer.Length > 0)
{
if (resolverStack.Count == 0)
{
return(cacheResponse);
}
else
{
ResolverData data = resolverStack.Pop();
question = data.Question;
nameServers = data.NameServers;
stackNameServerIndex = data.NameServerIndex;
switch (cacheResponse.Answer[0].Type)
{
case DnsResourceRecordType.AAAA:
nameServers[stackNameServerIndex] = new NameServerAddress(nameServers[stackNameServerIndex].Domain, (cacheResponse.Answer[0].RDATA as DnsAAAARecord).Address);
break;
case DnsResourceRecordType.A:
nameServers[stackNameServerIndex] = new NameServerAddress(nameServers[stackNameServerIndex].Domain, (cacheResponse.Answer[0].RDATA as DnsARecord).Address);
break;
default:
//didnt find IP for current name server
stackNameServerIndex++; //increment to skip current name server
break;
}
continue; //stack loop
}
}
if (cacheResponse.Authority.Length > 0)
{
if (cacheResponse.Authority[0].Type == DnsResourceRecordType.SOA)
{
if (resolverStack.Count == 0)
{
return(cacheResponse);
}
else
{
if (question.Type == DnsResourceRecordType.AAAA)
{
question = new DnsQuestionRecord(question.Name, DnsResourceRecordType.A, question.Class);
}
else
{
//didnt find IP for current name server
//pop and try next name server
ResolverData data = resolverStack.Pop();
question = data.Question;
nameServers = data.NameServers;
stackNameServerIndex = data.NameServerIndex + 1; //increment to skip current name server
}
continue; //to stack loop
}
}
if ((nameServers == null) || (nameServers.Length == 0))
{
NameServerAddress[] cacheNameServers = NameServerAddress.GetNameServersFromResponse(cacheResponse, preferIPv6, true);
if (cacheNameServers.Length > 0)
{
nameServers = cacheNameServers;
}
}
}
break;
case DnsResponseCode.NameError:
if (resolverStack.Count == 0)
{
return(cacheResponse);
}
else
{
//current name server domain doesnt exists
//pop and try next name server
ResolverData data = resolverStack.Pop();
question = data.Question;
nameServers = data.NameServers;
stackNameServerIndex = data.NameServerIndex + 1; //increment to skip current name server
continue; //stack loop
}
}
}
if ((nameServers == null) || (nameServers.Length == 0))
{
//create copy of root name servers array so that the values in original array are not messed due to shuffling feature
if (preferIPv6)
{
nameServers = new NameServerAddress[ROOT_NAME_SERVERS_IPv6.Length];
Array.Copy(ROOT_NAME_SERVERS_IPv6, nameServers, ROOT_NAME_SERVERS_IPv6.Length);
}
else
{
nameServers = new NameServerAddress[ROOT_NAME_SERVERS_IPv4.Length];
Array.Copy(ROOT_NAME_SERVERS_IPv4, nameServers, ROOT_NAME_SERVERS_IPv4.Length);
}
}
NameServerAddress.Shuffle(nameServers);
int hopCount = 0;
while ((hopCount++) < MAX_HOPS) //resolver loop
{
//copy and reset stack name server index since its one time use only after stack pop
int i = stackNameServerIndex;
stackNameServerIndex = 0;
//query name servers one by one
for (; i < nameServers.Length; i++) //retry next server loop
{
NameServerAddress currentNameServer = nameServers[i];
if (question.Name == currentNameServer.Domain)
{
continue; //obvious!
}
if (currentNameServer.EndPoint == null)
{
resolverStack.Push(new ResolverData(question, nameServers, i));
if (preferIPv6)
{
question = new DnsQuestionRecord(currentNameServer.Domain, DnsResourceRecordType.AAAA, question.Class);
}
else
{
question = new DnsQuestionRecord(currentNameServer.Domain, DnsResourceRecordType.A, question.Class);
}
nameServers = null;
goto stackLoop;
}
DnsClient client = new DnsClient(currentNameServer);
client._proxy = proxy;
client._preferIPv6 = preferIPv6;
client._tcp = tcp;
client._retries = retries;
DnsDatagram request = new DnsDatagram(new DnsHeader(0, false, DnsOpcode.StandardQuery, false, false, true, false, false, false, DnsResponseCode.NoError, 1, 0, 0, 0), new DnsQuestionRecord[] { question }, null, null, null);
DnsDatagram response;
try
{
response = client.Resolve(request);
}
catch (DnsClientException)
{
continue; //resolver loop
}
if (response.Header.Truncation)
{
if (tcp)
{
return(response);
}
client._tcp = true;
response = client.Resolve(request);
}
if (cache != null)
{
cache.CacheResponse(response);
}
switch (response.Header.RCODE)
{
case DnsResponseCode.NoError:
if (response.Answer.Length > 0)
{
if (!response.Answer[0].Name.Equals(question.Name, StringComparison.CurrentCultureIgnoreCase))
{
continue; //continue to next name server since current name server may be misconfigured
}
if (resolverStack.Count == 0)
{
return(response);
}
else
{
ResolverData data = resolverStack.Pop();
question = data.Question;
nameServers = data.NameServers;
stackNameServerIndex = data.NameServerIndex;
switch (response.Answer[0].Type)
{
case DnsResourceRecordType.AAAA:
nameServers[stackNameServerIndex] = new NameServerAddress(nameServers[stackNameServerIndex].Domain, (response.Answer[0].RDATA as DnsAAAARecord).Address);
break;
case DnsResourceRecordType.A:
nameServers[stackNameServerIndex] = new NameServerAddress(nameServers[stackNameServerIndex].Domain, (response.Answer[0].RDATA as DnsARecord).Address);
break;
default:
//didnt find IP for current name server
stackNameServerIndex++; //increment to skip current name server
break;
}
goto resolverLoop;
}
}
if (response.Authority.Length == 0)
{
continue; //continue to next name server since current name server may be misconfigured
}
if (response.Authority[0].Type == DnsResourceRecordType.SOA)
{
//no entry for given type
if (resolverStack.Count == 0)
{
return(response);
}
else
{
if (question.Type == DnsResourceRecordType.AAAA)
{
question = new DnsQuestionRecord(question.Name, DnsResourceRecordType.A, question.Class);
}
else
{
//didnt find IP for current name server
//pop and try next name server
ResolverData data = resolverStack.Pop();
question = data.Question;
nameServers = data.NameServers;
stackNameServerIndex = data.NameServerIndex + 1; //increment to skip current name server
}
goto stackLoop; //goto stack loop
}
}
nameServers = NameServerAddress.GetNameServersFromResponse(response, preferIPv6, false);
if (nameServers.Length == 0)
{
continue; //continue to next name server since current name server may be misconfigured
}
goto resolverLoop;
case DnsResponseCode.NameError:
if (resolverStack.Count == 0)
{
return(response);
}
else
{
//current name server domain doesnt exists
//pop and try next name server
ResolverData data = resolverStack.Pop();
question = data.Question;
nameServers = data.NameServers;
stackNameServerIndex = data.NameServerIndex + 1; //increment to skip current name server
goto stackLoop; //goto stack loop
}
default:
continue; //continue to next name server since current name server may be misconfigured
}
}
if (resolverStack.Count == 0)
{
throw new DnsClientException("DnsClient failed to resolve the request: no response from name servers.");
}
else
{
//didnt find IP for current name server
//pop and try next name server
ResolverData data = resolverStack.Pop();
question = data.Question;
nameServers = data.NameServers;
stackNameServerIndex = data.NameServerIndex + 1; //increment to skip current name server
break; //to stack loop
}
resolverLoop :;
}
stackLoop :;
}
}
protected override void Parse(Stream s)
{
_preference = DnsDatagram.ReadUInt16NetworkOrder(s);
_exchange = DnsDatagram.DeserializeDomainName(s);
}
public static DnsDatagram ReadFromJson(dynamic jsonResponse)
{
DnsDatagram datagram = new DnsDatagram();
datagram._QR = 1; //is response
datagram._OPCODE = DnsOpcode.StandardQuery;
datagram._TC = (byte)(jsonResponse.TC.Value ? 1 : 0);
datagram._RD = (byte)(jsonResponse.RD.Value ? 1 : 0);
datagram._RA = (byte)(jsonResponse.RA.Value ? 1 : 0);
datagram._AD = (byte)(jsonResponse.AD.Value ? 1 : 0);
datagram._CD = (byte)(jsonResponse.CD.Value ? 1 : 0);
datagram._RCODE = (DnsResponseCode)jsonResponse.Status;
//question
if (jsonResponse.Question == null)
{
datagram._question = Array.Empty <DnsQuestionRecord>();
}
else
{
ushort QDCOUNT = Convert.ToUInt16(jsonResponse.Question.Count);
List <DnsQuestionRecord> question = new List <DnsQuestionRecord>(QDCOUNT);
datagram._question = question;
foreach (dynamic jsonQuestionRecord in jsonResponse.Question)
{
question.Add(new DnsQuestionRecord(jsonQuestionRecord));
}
}
//answer
if (jsonResponse.Answer == null)
{
datagram._answer = Array.Empty <DnsResourceRecord>();
}
else
{
ushort ANCOUNT = Convert.ToUInt16(jsonResponse.Answer.Count);
List <DnsResourceRecord> answer = new List <DnsResourceRecord>(ANCOUNT);
datagram._answer = answer;
foreach (dynamic jsonAnswerRecord in jsonResponse.Answer)
{
answer.Add(new DnsResourceRecord(jsonAnswerRecord));
}
}
//authority
if (jsonResponse.Authority == null)
{
datagram._authority = Array.Empty <DnsResourceRecord>();
}
else
{
ushort NSCOUNT = Convert.ToUInt16(jsonResponse.Authority.Count);
List <DnsResourceRecord> authority = new List <DnsResourceRecord>(NSCOUNT);
datagram._authority = authority;
foreach (dynamic jsonAuthorityRecord in jsonResponse.Authority)
{
authority.Add(new DnsResourceRecord(jsonAuthorityRecord));
}
}
//additional
if (jsonResponse.Additional == null)
{
datagram._additional = Array.Empty <DnsResourceRecord>();
}
else
{
ushort ARCOUNT = Convert.ToUInt16(jsonResponse.Additional.Count);
List <DnsResourceRecord> additional = new List <DnsResourceRecord>(ARCOUNT);
datagram._additional = additional;
foreach (dynamic jsonAdditionalRecord in jsonResponse.Additional)
{
additional.Add(new DnsResourceRecord(jsonAdditionalRecord));
}
}
return(datagram);
}
public static async Task <DnsDatagram> ReadFromTcpAsync(Stream stream, MemoryStream sharedBuffer, CancellationToken cancellationToken = default)
{
DnsDatagram datagram = new DnsDatagram();
List <DnsQuestionRecord> question = null;
List <DnsResourceRecord> answer = null;
List <DnsResourceRecord> authority = null;
List <DnsResourceRecord> additional = null;
while (true)
{
if (question != null)
{
if (question.Count == 0)
{
break;
}
if (question[0].Type != DnsResourceRecordType.AXFR)
{
break;
}
if (answer.Count == 0)
{
break;
}
DnsResourceRecord lastAnswer = answer[answer.Count - 1];
if ((lastAnswer.Type == DnsResourceRecordType.SOA) && lastAnswer.Name.Equals(question[0].Name, StringComparison.OrdinalIgnoreCase))
{
break; //zone transfer complete
}
}
ushort length = await ReadUInt16NetworkOrderAsync(stream, cancellationToken);
sharedBuffer.SetLength(0);
await stream.CopyToAsync(sharedBuffer, 512, length, cancellationToken);
datagram._size += length;
sharedBuffer.Position = 0;
if (question == null)
{
datagram._ID = ReadUInt16NetworkOrder(sharedBuffer);
}
else
{
ushort ID = ReadUInt16NetworkOrder(sharedBuffer);
if (ID != datagram._ID)
{
throw new DnsClientException("Error while parsing TCP response: response ID does not match with previous response ID.");
}
}
int lB = sharedBuffer.ReadByte();
datagram._QR = Convert.ToByte((lB & 0x80) >> 7);
datagram._OPCODE = (DnsOpcode)Convert.ToByte((lB & 0x78) >> 3);
datagram._AA = Convert.ToByte((lB & 0x4) >> 2);
datagram._TC = Convert.ToByte((lB & 0x2) >> 1);
datagram._RD = Convert.ToByte(lB & 0x1);
int rB = sharedBuffer.ReadByte();
datagram._RA = Convert.ToByte((rB & 0x80) >> 7);
datagram._Z = Convert.ToByte((rB & 0x40) >> 6);
datagram._AD = Convert.ToByte((rB & 0x20) >> 5);
datagram._CD = Convert.ToByte((rB & 0x10) >> 4);
datagram._RCODE = (DnsResponseCode)(rB & 0xf);
ushort QDCOUNT = ReadUInt16NetworkOrder(sharedBuffer);
ushort ANCOUNT = ReadUInt16NetworkOrder(sharedBuffer);
ushort NSCOUNT = ReadUInt16NetworkOrder(sharedBuffer);
ushort ARCOUNT = ReadUInt16NetworkOrder(sharedBuffer);
if (question == null)
{
question = new List <DnsQuestionRecord>(QDCOUNT);
}
if (answer == null)
{
answer = new List <DnsResourceRecord>(ANCOUNT);
}
if (authority == null)
{
authority = new List <DnsResourceRecord>(NSCOUNT);
}
if (additional == null)
{
additional = new List <DnsResourceRecord>(ARCOUNT);
}
try
{
for (int i = 0; i < QDCOUNT; i++)
{
question.Add(new DnsQuestionRecord(sharedBuffer));
}
for (int i = 0; i < ANCOUNT; i++)
{
answer.Add(new DnsResourceRecord(sharedBuffer));
}
for (int i = 0; i < NSCOUNT; i++)
{
authority.Add(new DnsResourceRecord(sharedBuffer));
}
for (int i = 0; i < ARCOUNT; i++)
{
additional.Add(new DnsResourceRecord(sharedBuffer));
}
}
catch (Exception ex)
{
datagram._parsingException = ex;
break;
}
}
datagram._question = question;
datagram._answer = answer;
datagram._authority = authority;
datagram._additional = additional;
return(datagram);
}
public static DnsDatagram ReadFromUdp(Stream s)
{
DnsDatagram datagram = new DnsDatagram();
datagram._ID = ReadUInt16NetworkOrder(s);
int lB = s.ReadByte();
datagram._QR = Convert.ToByte((lB & 0x80) >> 7);
datagram._OPCODE = (DnsOpcode)Convert.ToByte((lB & 0x78) >> 3);
datagram._AA = Convert.ToByte((lB & 0x4) >> 2);
datagram._TC = Convert.ToByte((lB & 0x2) >> 1);
datagram._RD = Convert.ToByte(lB & 0x1);
int rB = s.ReadByte();
datagram._RA = Convert.ToByte((rB & 0x80) >> 7);
datagram._Z = Convert.ToByte((rB & 0x40) >> 6);
datagram._AD = Convert.ToByte((rB & 0x20) >> 5);
datagram._CD = Convert.ToByte((rB & 0x10) >> 4);
datagram._RCODE = (DnsResponseCode)(rB & 0xf);
ushort QDCOUNT = ReadUInt16NetworkOrder(s);
ushort ANCOUNT = ReadUInt16NetworkOrder(s);
ushort NSCOUNT = ReadUInt16NetworkOrder(s);
ushort ARCOUNT = ReadUInt16NetworkOrder(s);
List <DnsQuestionRecord> question = new List <DnsQuestionRecord>(QDCOUNT);
List <DnsResourceRecord> answer = new List <DnsResourceRecord>(ANCOUNT);
List <DnsResourceRecord> authority = new List <DnsResourceRecord>(NSCOUNT);
List <DnsResourceRecord> additional = new List <DnsResourceRecord>(ARCOUNT);
try
{
for (int i = 0; i < QDCOUNT; i++)
{
question.Add(new DnsQuestionRecord(s));
}
for (int i = 0; i < ANCOUNT; i++)
{
answer.Add(new DnsResourceRecord(s));
}
for (int i = 0; i < NSCOUNT; i++)
{
authority.Add(new DnsResourceRecord(s));
}
for (int i = 0; i < ARCOUNT; i++)
{
additional.Add(new DnsResourceRecord(s));
}
}
catch (Exception ex)
{
datagram._parsingException = ex;
}
datagram._question = question;
datagram._answer = answer;
datagram._authority = authority;
datagram._additional = additional;
return(datagram);
}
public static NameServerAddress[] GetNameServersFromResponse(DnsDatagram response, bool preferIPv6, bool selectOnlyNameServersWithGlue)
{
List <NameServerAddress> nameServers = new List <NameServerAddress>(response.Authority.Length);
DnsResourceRecord[] authorityRecords;
if ((response.Question.Length > 0) && (response.Question[0].Type == DnsResourceRecordType.NS) && (response.Answer.Length > 0))
{
authorityRecords = response.Answer;
}
else
{
authorityRecords = response.Authority;
}
foreach (DnsResourceRecord authorityRecord in authorityRecords)
{
if (authorityRecord.Type == DnsResourceRecordType.NS)
{
DnsNSRecord nsRecord = (DnsNSRecord)authorityRecord.RDATA;
IPEndPoint endPoint = null;
//find ip address of authoritative name server from additional records
foreach (DnsResourceRecord rr in response.Additional)
{
if (nsRecord.NSDomainName.Equals(rr.Name, StringComparison.OrdinalIgnoreCase))
{
switch (rr.Type)
{
case DnsResourceRecordType.A:
endPoint = new IPEndPoint(((DnsARecord)rr.RDATA).Address, 53);
nameServers.Add(new NameServerAddress(nsRecord.NSDomainName, endPoint));
break;
case DnsResourceRecordType.AAAA:
endPoint = new IPEndPoint(((DnsAAAARecord)rr.RDATA).Address, 53);
if (preferIPv6)
{
nameServers.Add(new NameServerAddress(nsRecord.NSDomainName, endPoint));
}
break;
}
}
}
if ((endPoint == null) && !selectOnlyNameServersWithGlue)
{
nameServers.Add(new NameServerAddress(new DomainEndPoint(nsRecord.NSDomainName, 53)));
}
}
}
NameServerAddress[] nsArray = nameServers.ToArray();
DnsClient.ShuffleArray(nsArray);
if (preferIPv6)
{
Array.Sort(nsArray);
}
return(nsArray);
}
public abstract DnsDatagram Query(DnsDatagram request);
public void CacheResponse(DnsDatagram response)
{
if (!response.Header.IsResponse || response.Header.Truncation || (response.Question.Length == 0))
{
return; //ineligible response
}
switch (response.Header.RCODE)
{
case DnsResponseCode.NoError:
case DnsResponseCode.NameError:
//cache response after this switch
break;
default:
//cache as failure record with RCODE
foreach (DnsQuestionRecord question in response.Question)
{
DnsResourceRecord record = new DnsResourceRecord(question.Name, question.Type, question.Class, _negativeRecordTtl, new DnsFailureRecord(response.Header.RCODE));
record.SetExpiry(_minimumRecordTtl, _serveStaleTtl);
CacheRecords(new DnsResourceRecord[] { record });
}
return;
}
//cache only NoError and NameError responses
//combine all records in the response
List <DnsResourceRecord> cachableRecords = new List <DnsResourceRecord>();
//get cachable answer records
foreach (DnsQuestionRecord question in response.Question)
{
string qName = question.Name;
foreach (DnsResourceRecord answer in response.Answer)
{
if (answer.Name.Equals(qName, StringComparison.OrdinalIgnoreCase))
{
cachableRecords.Add(answer);
switch (answer.Type)
{
case DnsResourceRecordType.CNAME:
qName = (answer.RDATA as DnsCNAMERecord).CNAMEDomainName;
break;
case DnsResourceRecordType.NS:
string nsDomain = (answer.RDATA as DnsNSRecord).NSDomainName;
if (!nsDomain.EndsWith(".root-servers.net", StringComparison.OrdinalIgnoreCase))
{
foreach (DnsResourceRecord record in response.Additional)
{
if (nsDomain.Equals(record.Name, StringComparison.OrdinalIgnoreCase))
{
cachableRecords.Add(record);
}
}
}
break;
case DnsResourceRecordType.MX:
string mxExchange = (answer.RDATA as DnsMXRecord).Exchange;
foreach (DnsResourceRecord record in response.Additional)
{
if (mxExchange.Equals(record.Name, StringComparison.OrdinalIgnoreCase))
{
cachableRecords.Add(record);
}
}
break;
}
}
}
}
//get cachable authority records
if (response.Authority.Length > 0)
{
DnsResourceRecord authority = response.Authority[0];
if (authority.Type == DnsResourceRecordType.SOA)
{
authority.SetExpiry(_minimumRecordTtl, _serveStaleTtl);
if (response.Answer.Length == 0)
{
//empty response with authority
foreach (DnsQuestionRecord question in response.Question)
{
if (question.Name.Equals(authority.Name, StringComparison.OrdinalIgnoreCase) || question.Name.EndsWith("." + authority.Name, StringComparison.OrdinalIgnoreCase) || authority.Name.Equals("", StringComparison.OrdinalIgnoreCase))
{
DnsResourceRecord record = null;
switch (response.Header.RCODE)
{
case DnsResponseCode.NameError:
record = new DnsResourceRecord(question.Name, question.Type, question.Class, (authority.RDATA as DnsSOARecord).Minimum, new DnsNXRecord(authority));
break;
case DnsResponseCode.NoError:
record = new DnsResourceRecord(question.Name, question.Type, question.Class, (authority.RDATA as DnsSOARecord).Minimum, new DnsEmptyRecord(authority));
break;
}
if (record != null)
{
record.SetExpiry(_minimumRecordTtl, _serveStaleTtl);
CacheRecords(new DnsResourceRecord[] { record });
}
}
}
}
else
{
//answer response with authority
DnsResourceRecord lastAnswer = response.Answer[response.Answer.Length - 1];
if (lastAnswer.Type == DnsResourceRecordType.CNAME)
{
foreach (DnsQuestionRecord question in response.Question)
{
if (question.Name.Equals(authority.Name, StringComparison.OrdinalIgnoreCase) || question.Name.EndsWith("." + authority.Name, StringComparison.OrdinalIgnoreCase))
{
DnsResourceRecord record = null;
switch (response.Header.RCODE)
{
case DnsResponseCode.NameError:
record = new DnsResourceRecord((lastAnswer.RDATA as DnsCNAMERecord).CNAMEDomainName, question.Type, question.Class, (authority.RDATA as DnsSOARecord).Minimum, new DnsNXRecord(authority));
break;
case DnsResponseCode.NoError:
record = new DnsResourceRecord((lastAnswer.RDATA as DnsCNAMERecord).CNAMEDomainName, question.Type, question.Class, (authority.RDATA as DnsSOARecord).Minimum, new DnsEmptyRecord(authority));
break;
}
if (record != null)
{
record.SetExpiry(_minimumRecordTtl, _serveStaleTtl);
CacheRecords(new DnsResourceRecord[] { record });
}
break;
}
}
}
}
}
else if (authority.Type == DnsResourceRecordType.NS)
{
if (response.Answer.Length == 0)
{
foreach (DnsQuestionRecord question in response.Question)
{
foreach (DnsResourceRecord authorityRecord in response.Authority)
{
if ((authorityRecord.Type == DnsResourceRecordType.NS) && (authorityRecord.RDATA as DnsNSRecord).NSDomainName.Equals(response.Metadata.NameServerAddress.Host, StringComparison.OrdinalIgnoreCase))
{
//empty response from authority name server that was queried
DnsResourceRecord record = null;
switch (response.Header.RCODE)
{
case DnsResponseCode.NameError:
record = new DnsResourceRecord(question.Name, question.Type, question.Class, _negativeRecordTtl, new DnsNXRecord(authority));
break;
case DnsResponseCode.NoError:
record = new DnsResourceRecord(question.Name, question.Type, question.Class, _negativeRecordTtl, new DnsEmptyRecord(authority));
break;
}
if (record != null)
{
record.SetExpiry(_minimumRecordTtl, _serveStaleTtl);
CacheRecords(new DnsResourceRecord[] { record });
}
break;
}
}
}
}
//cache suitable NS records
if ((response.Question[0].Type != DnsResourceRecordType.NS) || (response.Answer.Length == 0))
{
foreach (DnsQuestionRecord question in response.Question)
{
foreach (DnsResourceRecord authorityRecords in response.Authority)
{
if ((authorityRecords.Type == DnsResourceRecordType.NS) && (question.Name.Equals(authorityRecords.Name, StringComparison.OrdinalIgnoreCase) || question.Name.EndsWith("." + authorityRecords.Name, StringComparison.OrdinalIgnoreCase)))
{
cachableRecords.Add(authorityRecords);
string nsDomain = (authorityRecords.RDATA as DnsNSRecord).NSDomainName;
if (!nsDomain.EndsWith(".root-servers.net", StringComparison.OrdinalIgnoreCase))
{
foreach (DnsResourceRecord record in response.Additional)
{
if (nsDomain.Equals(record.Name, StringComparison.OrdinalIgnoreCase))
{
cachableRecords.Add(record);
}
}
}
}
}
}
}
}
}
else
{
//no authority records
if (response.Answer.Length == 0)
{
//empty response with no authority
foreach (DnsQuestionRecord question in response.Question)
{
DnsResourceRecord record = null;
switch (response.Header.RCODE)
{
case DnsResponseCode.NameError:
record = new DnsResourceRecord(question.Name, question.Type, question.Class, _negativeRecordTtl, new DnsNXRecord(null));
break;
case DnsResponseCode.NoError:
record = new DnsResourceRecord(question.Name, question.Type, question.Class, _negativeRecordTtl, new DnsEmptyRecord(null));
break;
}
if (record != null)
{
record.SetExpiry(_minimumRecordTtl, _serveStaleTtl);
CacheRecords(new DnsResourceRecord[] { record });
}
}
}
}
//cache for ANY request
if (response.Header.RCODE == DnsResponseCode.NoError)
{
if ((response.Question.Length == 1) && (response.Question[0].Type == DnsResourceRecordType.ANY))
{
DnsResourceRecord record = new DnsResourceRecord(response.Question[0].Name, DnsResourceRecordType.ANY, response.Question[0].Class, _negativeRecordTtl, new DnsANYRecord(response.Answer));
record.SetExpiry(_minimumRecordTtl, _serveStaleTtl);
CacheRecords(new DnsResourceRecord[] { record });
}
else
{
foreach (DnsQuestionRecord question in response.Question)
{
if (question.Type == DnsResourceRecordType.ANY)
{
List <DnsResourceRecord> answerRecords = new List <DnsResourceRecord>();
foreach (DnsResourceRecord answerRecord in response.Answer)
{
if (answerRecord.Name.Equals(question.Name, StringComparison.OrdinalIgnoreCase))
{
answerRecords.Add(answerRecord);
}
}
DnsResourceRecord record = new DnsResourceRecord(question.Name, DnsResourceRecordType.ANY, question.Class, _negativeRecordTtl, new DnsANYRecord(answerRecords.ToArray()));
record.SetExpiry(_minimumRecordTtl, _serveStaleTtl);
CacheRecords(new DnsResourceRecord[] { record });
}
}
}
}
if (cachableRecords.Count < 1)
{
return; //nothing to cache
}
//set expiry for cached records
foreach (DnsResourceRecord record in cachableRecords)
{
record.SetExpiry(_minimumRecordTtl, _serveStaleTtl);
}
CacheRecords(cachableRecords);
}
protected override void WriteRecordData(Stream s, List <DnsDomainOffset> domainEntries)
{
DnsDatagram.WriteUInt16NetworkOrder(_preference, s);
DnsDatagram.SerializeDomainName(_exchange, s, domainEntries);
}
public DnsDatagram Resolve(DnsDatagram request)
{
int bytesRecv;
byte[] responseBuffer = null;
int nextServerIndex = 0;
int retries = _retries;
byte[] requestBuffer;
IDnsCache dnsCache = null;
//serialize request
using (MemoryStream mS = new MemoryStream(32))
{
if (_tcp)
{
mS.Position = 2;
}
//write dns datagram
request.WriteTo(mS);
requestBuffer = mS.ToArray();
if (_tcp)
{
byte[] length = BitConverter.GetBytes(Convert.ToUInt16(requestBuffer.Length - 2));
requestBuffer[0] = length[1];
requestBuffer[1] = length[0];
}
}
//init server selection parameters
if (_servers.Length > 1)
{
retries = retries * _servers.Length; //retries on per server basis
byte[] select = new byte[1];
_rnd.GetBytes(select);
nextServerIndex = select[0] % _servers.Length;
}
int retry = 0;
while (retry < retries)
{
//select server
NameServerAddress server;
if (_servers.Length > 1)
{
server = _servers[nextServerIndex];
nextServerIndex = (nextServerIndex + 1) % _servers.Length;
}
else
{
server = _servers[0];
}
if (server.EndPoint == null)
{
if (dnsCache == null)
{
dnsCache = new SimpleDnsCache();
}
server.ResolveAddress(dnsCache, _proxy, _preferIPv6, _tcp, _retries);
if (server.EndPoint == null)
{
retry++;
continue;
}
}
//query server
Socket _socket = null;
SocksUdpAssociateRequestHandler proxyRequestHandler = null;
try
{
retry++;
DateTime sentAt = DateTime.UtcNow;
bool dnsTcp;
if (_proxy == null)
{
if (_tcp)
{
_socket = new Socket(server.EndPoint.AddressFamily, SocketType.Stream, ProtocolType.Tcp);
_socket.NoDelay = true;
_socket.SendTimeout = _sendTimeout;
_socket.ReceiveTimeout = _recvTimeout;
IAsyncResult result = _socket.BeginConnect(server.EndPoint, null, null);
if (!result.AsyncWaitHandle.WaitOne(_connectionTimeout))
{
throw new SocketException((int)SocketError.TimedOut);
}
if (!_socket.Connected)
{
throw new SocketException((int)SocketError.ConnectionRefused);
}
}
else
{
_socket = new Socket(server.EndPoint.AddressFamily, SocketType.Dgram, ProtocolType.Udp);
_socket.SendTimeout = _sendTimeout;
_socket.ReceiveTimeout = _recvTimeout;
}
dnsTcp = _tcp;
}
else
{
switch (_proxy.Type)
{
case NetProxyType.Http:
_socket = _proxy.HttpProxy.Connect(server.EndPoint, _connectionTimeout);
_socket.NoDelay = true;
_socket.SendTimeout = _sendTimeout;
_socket.ReceiveTimeout = _recvTimeout;
dnsTcp = true;
break;
case NetProxyType.Socks5:
if (!_tcp)
{
try
{
proxyRequestHandler = _proxy.SocksProxy.UdpAssociate(_connectionTimeout);
proxyRequestHandler.ReceiveTimeout = _recvTimeout;
dnsTcp = false;
break;
}
catch (SocksClientException)
{ }
}
using (SocksConnectRequestHandler requestHandler = _proxy.SocksProxy.Connect(server.EndPoint, _connectionTimeout))
{
_socket = requestHandler.GetSocket();
_socket.NoDelay = true;
_socket.SendTimeout = _sendTimeout;
_socket.ReceiveTimeout = _recvTimeout;
dnsTcp = true;
}
break;
default:
throw new NotSupportedException("Proxy type not supported by DnsClient.");
}
}
if (dnsTcp)
{
_socket.Send(requestBuffer);
if ((responseBuffer == null) || (responseBuffer.Length == 512))
{
responseBuffer = new byte[64 * 1024];
}
bytesRecv = _socket.Receive(responseBuffer, 0, 2, SocketFlags.None);
if (bytesRecv < 1)
{
throw new SocketException((int)SocketError.ConnectionReset);
}
Array.Reverse(responseBuffer, 0, 2);
ushort length = BitConverter.ToUInt16(responseBuffer, 0);
int offset = 0;
while (offset < length)
{
bytesRecv = _socket.Receive(responseBuffer, offset, length, SocketFlags.None);
if (bytesRecv < 1)
{
throw new SocketException((int)SocketError.ConnectionReset);
}
offset += bytesRecv;
}
bytesRecv = length;
}
else
{
if (responseBuffer == null)
{
responseBuffer = new byte[512];
}
if (proxyRequestHandler == null)
{
_socket.SendTo(requestBuffer, server.EndPoint);
EndPoint remoteEP;
if (server.EndPoint.AddressFamily == AddressFamily.InterNetworkV6)
{
remoteEP = new IPEndPoint(IPAddress.IPv6Any, 0);
}
else
{
remoteEP = new IPEndPoint(IPAddress.Any, 0);
}
bytesRecv = _socket.ReceiveFrom(responseBuffer, ref remoteEP);
}
else
{
proxyRequestHandler.SendTo(requestBuffer, 0, requestBuffer.Length, new SocksEndPoint(server.EndPoint));
bytesRecv = proxyRequestHandler.ReceiveFrom(responseBuffer, 0, responseBuffer.Length, out SocksEndPoint socksRemoteEP);
}
}
//parse response
using (MemoryStream mS = new MemoryStream(responseBuffer, 0, bytesRecv, false))
{
double rtt = (DateTime.UtcNow - sentAt).TotalMilliseconds;
DnsDatagram response = new DnsDatagram(mS, server, (_tcp ? ProtocolType.Tcp : ProtocolType.Udp), rtt);
if (response.Header.Identifier == request.Header.Identifier)
{
return(response);
}
}
}
catch (SocketException)
{ }
finally
{
if (_socket != null)
{
_socket.Dispose();
}
if (proxyRequestHandler != null)
{
proxyRequestHandler.Dispose();
}
}
}
throw new DnsClientException("DnsClient failed to resolve the request: no response from name servers.");
}
public DnsResourceRecord(Stream s)
{
_name = DnsDatagram.DeserializeDomainName(s);
_type = (DnsResourceRecordType)DnsDatagram.ReadUInt16NetworkOrder(s);
_class = (DnsClass)DnsDatagram.ReadUInt16NetworkOrder(s);
_ttl = DnsDatagram.ReadUInt32NetworkOrder(s);
switch (_type)
{
case DnsResourceRecordType.A:
_data = new DnsARecord(s);
break;
case DnsResourceRecordType.NS:
_data = new DnsNSRecord(s);
break;
case DnsResourceRecordType.CNAME:
_data = new DnsCNAMERecord(s);
break;
case DnsResourceRecordType.SOA:
_data = new DnsSOARecord(s);
break;
case DnsResourceRecordType.PTR:
_data = new DnsPTRRecord(s);
break;
case DnsResourceRecordType.MX:
_data = new DnsMXRecord(s);
break;
case DnsResourceRecordType.TXT:
_data = new DnsTXTRecord(s);
break;
case DnsResourceRecordType.AAAA:
_data = new DnsAAAARecord(s);
break;
case DnsResourceRecordType.SRV:
_data = new DnsSRVRecord(s);
break;
case DnsResourceRecordType.CAA:
_data = new DnsCAARecord(s);
break;
case DnsResourceRecordType.HINFO:
_data = new DnsHINFORecord(s);
break;
case DnsResourceRecordType.ANAME:
_data = new DnsANAMERecord(s);
break;
case DnsResourceRecordType.FWD:
_data = new DnsForwarderRecord(s);
break;
default:
_data = new DnsUnknownRecord(s);
break;
}
}
public override DnsDatagram Query(DnsDatagram request)
{
DnsQuestionRecord question = request.Question[0];
DnsResourceRecord[] answerRecords = GetRecords(question.Name, question.Type);
if (answerRecords != null)
{
if (answerRecords[0].RDATA is DnsEmptyRecord)
{
DnsResourceRecord[] responseAuthority;
DnsResourceRecord authority = (answerRecords[0].RDATA as DnsEmptyRecord).Authority;
if (authority == null)
{
responseAuthority = new DnsResourceRecord[] { }
}
;
else
{
responseAuthority = new DnsResourceRecord[] { authority }
};
return(new DnsDatagram(new DnsHeader(request.Header.Identifier, true, DnsOpcode.StandardQuery, false, false, request.Header.RecursionDesired, true, false, false, DnsResponseCode.NoError, 1, 0, 1, 0), request.Question, new DnsResourceRecord[] { }, responseAuthority, new DnsResourceRecord[] { }));
}
if (answerRecords[0].RDATA is DnsNXRecord)
{
DnsResourceRecord[] responseAuthority;
DnsResourceRecord authority = (answerRecords[0].RDATA as DnsNXRecord).Authority;
if (authority == null)
{
responseAuthority = new DnsResourceRecord[] { }
}
;
else
{
responseAuthority = new DnsResourceRecord[] { authority }
};
return(new DnsDatagram(new DnsHeader(request.Header.Identifier, true, DnsOpcode.StandardQuery, false, false, request.Header.RecursionDesired, true, false, false, DnsResponseCode.NameError, 1, 0, 1, 0), request.Question, new DnsResourceRecord[] { }, responseAuthority, new DnsResourceRecord[] { }));
}
if (answerRecords[0].RDATA is DnsANYRecord)
{
DnsANYRecord anyRR = answerRecords[0].RDATA as DnsANYRecord;
return(new DnsDatagram(new DnsHeader(request.Header.Identifier, true, DnsOpcode.StandardQuery, false, false, request.Header.RecursionDesired, true, false, false, DnsResponseCode.NoError, 1, (ushort)anyRR.Records.Length, 0, 0), request.Question, anyRR.Records, new DnsResourceRecord[] { }, new DnsResourceRecord[] { }));
}
if (answerRecords[0].RDATA is DnsFailureRecord)
{
return(new DnsDatagram(new DnsHeader(request.Header.Identifier, true, DnsOpcode.StandardQuery, false, false, request.Header.RecursionDesired, true, false, false, (answerRecords[0].RDATA as DnsFailureRecord).RCODE, 1, 0, 0, 0), request.Question, new DnsResourceRecord[] { }, new DnsResourceRecord[] { }, new DnsResourceRecord[] { }));
}
return(new DnsDatagram(new DnsHeader(request.Header.Identifier, true, DnsOpcode.StandardQuery, false, false, request.Header.RecursionDesired, true, false, false, DnsResponseCode.NoError, 1, (ushort)answerRecords.Length, 0, 0), request.Question, answerRecords, new DnsResourceRecord[] { }, new DnsResourceRecord[] { }));
}
string currentZone = question.Name;
while (currentZone != null)
{
DnsResourceRecord[] nameServers = GetClosestNameServers(currentZone);
if (nameServers == null)
{
break;
}
List <DnsResourceRecord> glueRecords = new List <DnsResourceRecord>();
foreach (DnsResourceRecord nameServer in nameServers)
{
string nsDomain = (nameServer.RDATA as DnsNSRecord).NSDomainName;
DnsResourceRecord[] glueAs = GetRecords(nsDomain, DnsResourceRecordType.A);
if ((glueAs != null) && (glueAs.Length > 0) && (glueAs[0].RDATA is DnsARecord))
{
glueRecords.AddRange(glueAs);
}
DnsResourceRecord[] glueAAAAs = GetRecords(nsDomain, DnsResourceRecordType.AAAA);
if ((glueAAAAs != null) && (glueAAAAs.Length > 0) && (glueAAAAs[0].RDATA is DnsAAAARecord))
{
glueRecords.AddRange(glueAAAAs);
}
}
if (glueRecords.Count > 0)
{
DnsResourceRecord[] additional = glueRecords.ToArray();
return(new DnsDatagram(new DnsHeader(request.Header.Identifier, true, DnsOpcode.StandardQuery, false, false, request.Header.RecursionDesired, true, false, false, DnsResponseCode.NoError, 1, 0, (ushort)nameServers.Length, (ushort)additional.Length), request.Question, new DnsResourceRecord[] { }, nameServers, additional));
}
currentZone = GetParentZone(currentZone);
}
return(new DnsDatagram(new DnsHeader(request.Header.Identifier, true, DnsOpcode.StandardQuery, false, false, request.Header.RecursionDesired, true, false, false, DnsResponseCode.Refused, 1, 0, 0, 0), request.Question, new DnsResourceRecord[] { }, new DnsResourceRecord[] { }, new DnsResourceRecord[] { }));
}
public virtual DnsDatagram Query(DnsDatagram request, bool serveStale = false)
{
if (serveStale)
{
throw new NotImplementedException("DnsCache does not implement serve stale.");
}
DnsQuestionRecord question = request.Question[0];
IReadOnlyList <DnsResourceRecord> answerRecords = GetRecords(question.Name, question.Type);
if (answerRecords != null)
{
if (answerRecords[0].RDATA is DnsEmptyRecord)
{
DnsResourceRecord[] responseAuthority;
DnsResourceRecord authority = (answerRecords[0].RDATA as DnsEmptyRecord).Authority;
if (authority == null)
{
responseAuthority = Array.Empty <DnsResourceRecord>();
}
else
{
responseAuthority = new DnsResourceRecord[] { authority }
};
return(new DnsDatagram(request.Identifier, true, DnsOpcode.StandardQuery, false, false, request.RecursionDesired, true, false, false, DnsResponseCode.NoError, request.Question, null, responseAuthority));
}
if (answerRecords[0].RDATA is DnsNXRecord)
{
DnsResourceRecord[] responseAuthority;
DnsResourceRecord authority = (answerRecords[0].RDATA as DnsNXRecord).Authority;
if (authority == null)
{
responseAuthority = Array.Empty <DnsResourceRecord>();
}
else
{
responseAuthority = new DnsResourceRecord[] { authority }
};
return(new DnsDatagram(request.Identifier, true, DnsOpcode.StandardQuery, false, false, request.RecursionDesired, true, false, false, DnsResponseCode.NameError, request.Question, null, responseAuthority));
}
if (answerRecords[0].RDATA is DnsANYRecord)
{
DnsANYRecord anyRR = answerRecords[0].RDATA as DnsANYRecord;
return(new DnsDatagram(request.Identifier, true, DnsOpcode.StandardQuery, false, false, request.RecursionDesired, true, false, false, DnsResponseCode.NoError, request.Question, anyRR.Records));
}
if (answerRecords[0].RDATA is DnsFailureRecord)
{
return(new DnsDatagram(request.Identifier, true, DnsOpcode.StandardQuery, false, false, request.RecursionDesired, true, false, false, (answerRecords[0].RDATA as DnsFailureRecord).RCODE, request.Question));
}
return(new DnsDatagram(request.Identifier, true, DnsOpcode.StandardQuery, false, false, request.RecursionDesired, true, false, false, DnsResponseCode.NoError, request.Question, answerRecords));
}
string currentZone = question.Name;
while (currentZone != null)
{
IReadOnlyList <DnsResourceRecord> nameServers = GetClosestNameServers(currentZone);
if (nameServers == null)
{
break;
}
List <DnsResourceRecord> glueRecords = new List <DnsResourceRecord>();
foreach (DnsResourceRecord nameServer in nameServers)
{
string nsDomain = (nameServer.RDATA as DnsNSRecord).NameServer;
IReadOnlyList <DnsResourceRecord> glueAs = GetRecords(nsDomain, DnsResourceRecordType.A);
if ((glueAs != null) && (glueAs.Count > 0) && (glueAs[0].RDATA is DnsARecord))
{
glueRecords.AddRange(glueAs);
}
IReadOnlyList <DnsResourceRecord> glueAAAAs = GetRecords(nsDomain, DnsResourceRecordType.AAAA);
if ((glueAAAAs != null) && (glueAAAAs.Count > 0) && (glueAAAAs[0].RDATA is DnsAAAARecord))
{
glueRecords.AddRange(glueAAAAs);
}
}
if (glueRecords.Count > 0)
{
return(new DnsDatagram(request.Identifier, true, DnsOpcode.StandardQuery, false, false, request.RecursionDesired, true, false, false, DnsResponseCode.NoError, request.Question, null, nameServers, glueRecords));
}
currentZone = GetParentZone(currentZone);
}
return(new DnsDatagram(request.Identifier, true, DnsOpcode.StandardQuery, false, false, request.RecursionDesired, true, false, false, DnsResponseCode.Refused, request.Question));
}
public void CacheResponse(DnsDatagram response)
{
if (!response.Header.IsResponse)
{
return;
}
//combine all records in the response
List <DnsResourceRecord> allRecords = new List <DnsResourceRecord>();
switch (response.Header.RCODE)
{
case DnsResponseCode.NameError:
if (response.Authority.Length > 0)
{
DnsResourceRecord authority = response.Authority[0];
if (authority.Type == DnsResourceRecordType.SOA)
{
foreach (DnsQuestionRecord question in response.Question)
{
DnsResourceRecord record = new DnsResourceRecord(question.Name, question.Type, DnsClass.IN, DEFAULT_RECORD_TTL, new DnsNXRecord(authority));
record.SetExpiry();
CacheEntry(question.Name, question.Type, new DnsResourceRecord[] { record });
}
}
}
break;
case DnsResponseCode.NoError:
if ((response.Answer.Length == 0) && (response.Authority.Length > 0))
{
DnsResourceRecord authority = response.Authority[0];
if (authority.Type == DnsResourceRecordType.SOA)
{
foreach (DnsQuestionRecord question in response.Question)
{
DnsResourceRecord record = new DnsResourceRecord(question.Name, question.Type, DnsClass.IN, DEFAULT_RECORD_TTL, new DnsEmptyRecord(authority));
record.SetExpiry();
CacheEntry(question.Name, question.Type, new DnsResourceRecord[] { record });
}
}
}
else
{
allRecords.AddRange(response.Answer);
}
break;
default:
return; //nothing to do
}
allRecords.AddRange(response.Authority);
allRecords.AddRange(response.Additional);
#region group all records by domain and type
Dictionary <string, Dictionary <DnsResourceRecordType, List <DnsResourceRecord> > > cacheEntries = new Dictionary <string, Dictionary <DnsResourceRecordType, List <DnsResourceRecord> > >();
foreach (DnsResourceRecord record in allRecords)
{
Dictionary <DnsResourceRecordType, List <DnsResourceRecord> > cacheTypeEntries;
if (cacheEntries.ContainsKey(record.Name))
{
cacheTypeEntries = cacheEntries[record.Name];
}
else
{
cacheTypeEntries = new Dictionary <DnsResourceRecordType, List <DnsResourceRecord> >();
cacheEntries.Add(record.Name, cacheTypeEntries);
}
List <DnsResourceRecord> cacheRREntries;
if (cacheTypeEntries.ContainsKey(record.Type))
{
cacheRREntries = cacheTypeEntries[record.Type];
}
else
{
cacheRREntries = new List <DnsResourceRecord>();
cacheTypeEntries.Add(record.Type, cacheRREntries);
}
cacheRREntries.Add(record);
}
#endregion
//add grouped entries into cache
foreach (KeyValuePair <string, Dictionary <DnsResourceRecordType, List <DnsResourceRecord> > > cacheEntry in cacheEntries)
{
string domain = cacheEntry.Key;
foreach (KeyValuePair <DnsResourceRecordType, List <DnsResourceRecord> > cacheTypeEntry in cacheEntry.Value)
{
DnsResourceRecordType type = cacheTypeEntry.Key;
DnsResourceRecord[] records = cacheTypeEntry.Value.ToArray();
foreach (DnsResourceRecord record in records)
{
record.SetExpiry();
}
CacheEntry(domain, type, records);
}
}
//cache for ANY request
if (response.Question[0].Type == DnsResourceRecordType.ANY)
{
CacheEntry(response.Question[0].Name, DnsResourceRecordType.ANY, response.Answer);
}
}
public virtual DnsDatagram Query(DnsDatagram request, bool serveStale = false)
{
if (serveStale)
{
throw new NotImplementedException("DnsCache does not implement serve stale.");
}
DnsQuestionRecord question = request.Question[0];
IReadOnlyList <DnsResourceRecord> answerRecords = GetRecords(question.Name, question.Type);
if (answerRecords != null)
{
if (answerRecords[0].RDATA is DnsEmptyRecord)
{
DnsResourceRecord[] responseAuthority;
DnsResourceRecord authority = (answerRecords[0].RDATA as DnsEmptyRecord).Authority;
if (authority == null)
{
responseAuthority = Array.Empty <DnsResourceRecord>();
}
else
{
responseAuthority = new DnsResourceRecord[] { authority }
};
return(new DnsDatagram(request.Identifier, true, DnsOpcode.StandardQuery, false, false, request.RecursionDesired, true, false, false, DnsResponseCode.NoError, request.Question, null, responseAuthority));
}
if (answerRecords[0].RDATA is DnsNXRecord)
{
DnsResourceRecord[] responseAuthority;
DnsResourceRecord authority = (answerRecords[0].RDATA as DnsNXRecord).Authority;
if (authority == null)
{
responseAuthority = Array.Empty <DnsResourceRecord>();
}
else
{
responseAuthority = new DnsResourceRecord[] { authority }
};
return(new DnsDatagram(request.Identifier, true, DnsOpcode.StandardQuery, false, false, request.RecursionDesired, true, false, false, DnsResponseCode.NameError, request.Question, null, responseAuthority));
}
if (answerRecords[0].RDATA is DnsANYRecord)
{
DnsANYRecord anyRR = answerRecords[0].RDATA as DnsANYRecord;
return(new DnsDatagram(request.Identifier, true, DnsOpcode.StandardQuery, false, false, request.RecursionDesired, true, false, false, DnsResponseCode.NoError, request.Question, anyRR.Records));
}
if (answerRecords[0].RDATA is DnsFailureRecord)
{
return(new DnsDatagram(request.Identifier, true, DnsOpcode.StandardQuery, false, false, request.RecursionDesired, true, false, false, (answerRecords[0].RDATA as DnsFailureRecord).RCODE, request.Question));
}
IReadOnlyList <DnsResourceRecord> additionalRecords = null;
switch (question.Type)
{
case DnsResourceRecordType.NS:
case DnsResourceRecordType.MX:
case DnsResourceRecordType.SRV:
additionalRecords = GetAdditionalRecords(answerRecords);
break;
}
return(new DnsDatagram(request.Identifier, true, DnsOpcode.StandardQuery, false, false, request.RecursionDesired, true, false, false, DnsResponseCode.NoError, request.Question, answerRecords, null, additionalRecords));
}
IReadOnlyList <DnsResourceRecord> closestAuthority = GetClosestNameServers(question.Name);
if (closestAuthority != null)
{
IReadOnlyList <DnsResourceRecord> additionalRecords = GetAdditionalRecords(closestAuthority);
return(new DnsDatagram(request.Identifier, true, DnsOpcode.StandardQuery, false, false, request.RecursionDesired, true, false, false, DnsResponseCode.NoError, request.Question, null, closestAuthority, additionalRecords));
}
return(new DnsDatagram(request.Identifier, true, DnsOpcode.StandardQuery, false, false, request.RecursionDesired, true, false, false, DnsResponseCode.Refused, request.Question));
}
public void WriteTo(Stream s, List <DnsDomainOffset> domainEntries)
{
DnsDatagram.SerializeDomainName(_name, s, domainEntries);
DnsDatagram.WriteUInt16NetworkOrder((ushort)_type, s);
DnsDatagram.WriteUInt16NetworkOrder((ushort)_class, s);
}
protected override void Parse(Stream s)
{
_nsDomainName = DnsDatagram.ConvertLabelToDomain(s);
}
protected override void WriteRecordData(Stream s, List <DnsDomainOffset> domainEntries)
{
DnsDatagram.SerializeDomainName(_ptrDomainName, s, domainEntries);
}
protected override void WriteRecordData(Stream s, List <DnsDomainOffset> domainEntries)
{
DnsDatagram.ConvertDomainToLabel(_nsDomainName, s, domainEntries);
}
public void WriteTo(Stream s, List <DnsDomainOffset> domainEntries)
{
DnsDatagram.ConvertDomainToLabel(_name, s, domainEntries);
DnsDatagram.WriteUInt16NetworkOrder((ushort)_type, s);
DnsDatagram.WriteUInt16NetworkOrder((ushort)_class, s);
}
public void RecursiveResolveIPAddress(DnsCache cache = null, NetProxy proxy = null, bool preferIPv6 = false, DnsTransportProtocol protocol = DnsTransportProtocol.Udp, int retries = 2, int timeout = 2000, DnsTransportProtocol recursiveResolveProtocol = DnsTransportProtocol.Udp)
{
lock (_ipEndPointResolverLock)
{
if (_ipEndPointExpires && (DateTime.UtcNow < _ipEndPointExpiresOn))
{
return;
}
string domain;
if (_dohEndPoint != null)
{
domain = _dohEndPoint.Host;
}
else if (_domainEndPoint != null)
{
domain = _domainEndPoint.Address;
}
else
{
return;
}
if (domain == "localhost")
{
_ipEndPoint = new IPEndPoint((preferIPv6 ? IPAddress.IPv6Loopback : IPAddress.Loopback), this.Port);
return;
}
if (IPAddress.TryParse(domain, out IPAddress address))
{
_ipEndPoint = new IPEndPoint(address, this.Port);
return;
}
IPEndPoint ipEndPoint = null;
DateTime ipEndPointExpiresOn = DateTime.MinValue;
if (preferIPv6)
{
DnsDatagram nsResponse = DnsClient.RecursiveResolve(new DnsQuestionRecord(domain, DnsResourceRecordType.AAAA, DnsClass.IN), null, cache, proxy, true, protocol, retries, timeout, recursiveResolveProtocol);
if ((nsResponse.Header.RCODE == DnsResponseCode.NoError) && (nsResponse.Answer.Length > 0) && (nsResponse.Answer[0].Type == DnsResourceRecordType.AAAA))
{
ipEndPoint = new IPEndPoint((nsResponse.Answer[0].RDATA as DnsAAAARecord).Address, this.Port);
ipEndPointExpiresOn = DateTime.UtcNow.AddSeconds(nsResponse.Answer[0].TtlValue);
}
}
if (ipEndPoint == null)
{
DnsDatagram nsResponse = DnsClient.RecursiveResolve(new DnsQuestionRecord(domain, DnsResourceRecordType.A, DnsClass.IN), null, cache, proxy, false, protocol, retries, timeout, recursiveResolveProtocol);
if ((nsResponse.Header.RCODE == DnsResponseCode.NoError) && (nsResponse.Answer.Length > 0) && (nsResponse.Answer[0].Type == DnsResourceRecordType.A))
{
ipEndPoint = new IPEndPoint((nsResponse.Answer[0].RDATA as DnsARecord).Address, this.Port);
ipEndPointExpiresOn = DateTime.UtcNow.AddSeconds(nsResponse.Answer[0].TtlValue);
}
}
if (ipEndPoint == null)
{
throw new DnsClientException("No IP address was found for name server: " + domain);
}
_ipEndPoint = ipEndPoint;
_ipEndPointExpires = true;
_ipEndPointExpiresOn = ipEndPointExpiresOn;
}
}
