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 :;
}
}
public DnsPTRRecord(string ptrDomainName)
{
DnsClient.IsDomainNameValid(ptrDomainName, true);
_ptrDomainName = ptrDomainName;
}
public DnsCNAMERecord(string cnameDomainName)
{
DnsClient.IsDomainNameValid(cnameDomainName, true);
_cnameDomainName = cnameDomainName;
}
public DnsNSRecord(string nsDomainName)
{
DnsClient.IsDomainNameValid(nsDomainName, true);
_nsDomainName = nsDomainName;
}
public void ResolveIPAddress(NameServerAddress[] nameServers = null, NetProxy proxy = null, bool preferIPv6 = false, int retries = 2, int timeout = 2000, DnsTransportProtocol protocol = 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;
}
DnsClient dnsClient;
if (nameServers == null)
{
dnsClient = new DnsClient();
}
else
{
dnsClient = new DnsClient(nameServers);
}
dnsClient.Proxy = proxy;
dnsClient.PreferIPv6 = preferIPv6;
dnsClient.Protocol = protocol;
dnsClient.Retries = retries;
dnsClient.Timeout = timeout;
IPAddress[] serverIPs = dnsClient.ResolveIP(domain, preferIPv6);
if (serverIPs.Length == 0)
{
throw new DnsClientException("No IP address was found for name server: " + domain);
}
_ipEndPoint = new IPEndPoint(serverIPs[0], this.Port);
_ipEndPointExpires = true;
_ipEndPointExpiresOn = DateTime.UtcNow.AddSeconds(IP_ENDPOINT_DEFAULT_TTL);
}
}
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 async Task RecursiveResolveDomainNameAsync(IDnsCache cache = null, NetProxy proxy = null, bool preferIPv6 = false, bool randomizeName = false, int retries = 2, int timeout = 2000)
{
if (_ipEndPoint != null)
{
try
{
IReadOnlyList <string> ptrDomains = DnsClient.ParseResponsePTR(await DnsClient.RecursiveResolveQueryAsync(new DnsQuestionRecord(_ipEndPoint.Address, DnsClass.IN), cache, proxy, preferIPv6, randomizeName, retries, timeout));
if (ptrDomains != null)
{
_domainEndPoint = new DomainEndPoint(ptrDomains[0], _ipEndPoint.Port);
}
}
catch
{ }
}
}
public async Task ResolveIPAddressAsync(IReadOnlyList <NameServerAddress> nameServers = null, NetProxy proxy = null, bool preferIPv6 = false, bool randomizeName = false, int retries = 2, int timeout = 2000)
{
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, Port);
return;
}
if (IPAddress.TryParse(domain, out IPAddress address))
{
_ipEndPoint = new IPEndPoint(address, Port);
return;
}
DnsClient dnsClient;
if (nameServers == null)
{
dnsClient = new DnsClient();
}
else
{
dnsClient = new DnsClient(nameServers);
}
dnsClient.Proxy = proxy;
dnsClient.PreferIPv6 = preferIPv6;
dnsClient.RandomizeName = randomizeName;
dnsClient.Retries = retries;
dnsClient.Timeout = timeout;
IReadOnlyList <IPAddress> serverIPs = await dnsClient.ResolveIPAsync(domain, preferIPv6);
if (serverIPs.Count == 0)
{
throw new DnsClientException("No IP address was found for name server: " + domain);
}
_ipEndPoint = new IPEndPoint(serverIPs[0], this.Port);
_ipEndPointExpires = true;
_ipEndPointExpiresOn = DateTime.UtcNow.AddSeconds(IP_ENDPOINT_DEFAULT_TTL);
}
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;
}
}
