public DnsDatagram(Stream s, NameServerAddress server = null, ProtocolType protocol = ProtocolType.Udp, double rtt = 0)
{
_server = server;
_protocol = protocol;
_size = s.Length;
_rtt = rtt;
_header = new DnsHeader(s);
_question = new DnsQuestionRecord[_header.QDCOUNT];
for (int i = 0; i < _header.QDCOUNT; i++)
{
_question[i] = new DnsQuestionRecord(s);
}
_answer = new DnsResourceRecord[_header.ANCOUNT];
for (int i = 0; i < _header.ANCOUNT; i++)
{
_answer[i] = new DnsResourceRecord(s);
}
_authority = new DnsResourceRecord[_header.NSCOUNT];
for (int i = 0; i < _header.NSCOUNT; i++)
{
_authority[i] = new DnsResourceRecord(s);
}
_additional = new DnsResourceRecord[_header.ARCOUNT];
for (int i = 0; i < _header.ARCOUNT; i++)
{
_additional[i] = new DnsResourceRecord(s);
}
}
public DnsDatagramMetadata(NameServerAddress server, DnsTransportProtocol protocol, int size, double rtt)
{
_server = server;
_protocol = protocol;
_size = size;
_rtt = rtt;
if (_rtt < 0.1)
{
_rtt = 0.1;
}
}
public DnsClient(IPAddress[] servers)
{
if (servers.Length == 0)
{
throw new DnsClientException("Atleast one name server must be available for DnsClient.");
}
_servers = new NameServerAddress[servers.Length];
for (int i = 0; i < servers.Length; i++)
{
_servers[i] = new NameServerAddress(servers[i]);
}
}
public DnsClient(bool preferIPv6 = false)
{
_preferIPv6 = preferIPv6;
NetworkInfo defaultNetworkInfo;
if (_preferIPv6)
{
defaultNetworkInfo = NetUtilities.GetDefaultIPv6NetworkInfo();
if ((defaultNetworkInfo == null) || (defaultNetworkInfo.Interface.GetIPProperties().DnsAddresses.Count == 0))
{
defaultNetworkInfo = NetUtilities.GetDefaultIPv4NetworkInfo();
}
}
else
{
defaultNetworkInfo = NetUtilities.GetDefaultIPv4NetworkInfo();
}
if (defaultNetworkInfo == null)
{
throw new DnsClientException("No default network connection was found on this computer.");
}
IPAddressCollection servers = defaultNetworkInfo.Interface.GetIPProperties().DnsAddresses;
if (servers.Count == 0)
{
throw new DnsClientException("Default network does not have any DNS server configured.");
}
_servers = new NameServerAddress[servers.Count];
for (int i = 0; i < servers.Count; i++)
{
_servers[i] = new NameServerAddress(servers[i]);
}
}
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 DnsClient(NameServerAddress server)
{
_servers = new NameServerAddress[] { server };
}