/// <summary>
/// Handle the DNS query.
/// </summary>
public DnsResponse Get(DnsRequest request)
{
if (request == null)
{
throw new ArgumentNullException("request");
}
DnsQuestion question = request.Question;
if (question == null || question.Class != DnsStandard.Class.IN)
{
throw new DnsServerException(DnsStandard.ResponseCode.NotImplemented);
}
/* Don't handle NS and SOA record recursilvey since these are retrieved from the primary
* DNS servers and are cached. So, we would always end up retrieving the cached values
* from the primary DNS servers. */
if (request.Question.Type != DnsStandard.RecordType.ANAME &&
request.Question.Type != DnsStandard.RecordType.CERT &&
request.Question.Type != DnsStandard.RecordType.CNAME &&
request.Question.Type != DnsStandard.RecordType.MX)
{
throw new DnsServerException(DnsStandard.ResponseCode.NotImplemented);
}
DnsResponse response = ProcessRequest(request);
return(response);
}
/// <summary>
/// processes a SRV Question, populated the response with any matching results pulled from the database store
/// </summary>
/// <param name="response">DnsResponse instance containing information about the question that will
/// have any corresponding answer records populated upon return</param>
protected void ProcessSRVQuestion(DnsResponse response)
{
using (RecordRetrievalServiceClient client = m_recordRetrievalServiceSettings.CreateRecordRetrievalClient())
{
client.GetSRVRecords(response.Question.Domain, response.AnswerRecords);
}
}
public void Send(DnsResponse response)
{
DnsBuffer buffer = new DnsBuffer();
response.Serialize(buffer);
this.SendBuffer(buffer);
}
DnsResponse CreateResponse(DnsRequest request, IEnumerable <DnsResourceRecord> matches)
{
DnsStandard.RecordType questionType = request.Question.Type;
DnsResponse response = new DnsResponse(request);
int matchCount = 0;
foreach (DnsResourceRecord record in matches)
{
if (record.Type == questionType)
{
++matchCount;
switch (record.Type)
{
default:
response.AnswerRecords.Add(record);
break;
case DnsStandard.RecordType.NS:
case DnsStandard.RecordType.SOA:
response.AnswerRecords.Add(record);
break;
}
}
}
if (matchCount == 0)
{
throw new DnsServerException(DnsStandard.ResponseCode.NameError);
}
return(response);
}
/// <summary>
/// this routine populates the cache with items and confirms that they are in there
/// </summary>
public void PopulateBasicCache()
{
m_drrc = new DnsResponseCache(Guid.NewGuid().ToString("D"));
DumpSuccess("");
// populate the entires
PopulateMockDnsARecordResponseEntries();
// force static TTL
ForceTtlTime(m_basettl);
foreach (DnsResponse dr in m_responses)
{
m_drrc.Put(dr);
}
DumpSuccess("Checking for {0} items stored in cache", m_responses.Count());
// make sure that the cache count reflects 10 entries
Assert.Equal(m_responses.Count(), m_drrc.CacheCount);
DumpSuccess("Checking all entries in cache to make sure they exist as expected");
// check the entries to make sure that all are found in the cache
foreach (DnsResponse dr in m_responses)
{
DnsResponse res = m_drrc.Get(dr.Question);
// make sure that the expect entry was found
Assert.NotNull(res);
}
}
public DnsResponse Get(DnsRequest request)
{
ushort requestID = request.RequestID;
DnsResponse response = null;
try
{
using (DnsClient client = new DnsClient(m_serverIP))
{
if (m_timeout != null)
{
client.Timeout = m_timeout.Value;
}
response = client.Resolve(request);
}
}
finally
{
if (response != null)
{
response.RequestID = requestID;
}
request.RequestID = requestID;
}
return(response);
}
internal DnsClientResponse(DnsClientRequest request, DnsResponse response, byte[] message)
{
Request = request;
_message = message;
_response = response;
}
void HandleRequest(IAsyncResult result)
{
try
{
using (Socket socket = m_listener.EndAcceptSocket(result))
{
TestTCPClient client = new TestTCPClient(socket); // Chunk sends
DnsRequest request = client.ReceiveRequest();
DnsResponse response = null;
try
{
response = m_store.Get(request);
if (response == null)
{
response = new DnsResponse(request);
response.Header.ResponseCode = DnsStandard.ResponseCode.NameError;
}
}
catch
{
response = new DnsResponse(request);
response.Header.ResponseCode = DnsStandard.ResponseCode.NameError;
}
if (response != null)
{
client.Send(response);
}
}
}
catch
{
}
}
public void DnsResolve(string[] args)
{
string domain = args.GetRequiredValue(0);
DnsStandard.RecordType recordType = args.GetOptionalEnum <DnsStandard.RecordType>(1, DnsStandard.RecordType.ANAME);
try
{
using (DnsClient client = CreateClient())
{
client.UseUDPFirst = (recordType != DnsStandard.RecordType.CERT);
DnsResponse response = client.Resolve(new DnsRequest(recordType, domain));
if (response == null)
{
Console.WriteLine("No matches");
return;
}
m_recordPrinter.Print(response);
}
}
catch (DnsServerException ex)
{
Console.WriteLine(ex.ResponseCode);
}
}
DnsResponse ProcessError(DnsRequest request, DnsStandard.ResponseCode code)
{
DnsResponse errorResponse = new DnsResponse(request);
errorResponse.Header.ResponseCode = code;
return(errorResponse);
}
public void TestTypeSRVSort()
{
DnsResponse response = new DnsResponse();
response.AnswerRecords.Add(new SRVRecord("foo.order.com", 100, 389, "x.y.z.com", 50));
response.AnswerRecords.Add(new SRVRecord("foo.order.com", 100, 389, "x.y.z.com", 100));
response.AnswerRecords.Add(new SRVRecord("foo.order.com", 0, 389, "x.y.z.com", 0));
response.AnswerRecords.Add(new SRVRecord("foo.order.com", 0, 389, "x.y.z.com", 50));
response.AnswerRecords.Add(new SRVRecord("foo.order.com", 0, 389, "x.y.z.com", 100));
List <SRVRecord> responseList = response.AnswerRecords.SRV
.OrderBy(r => r.Priority)
.OrderByDescending(r => r.Weight)
.ToList();
Assert.NotEqual(responseList[0].ToString(), "foo.order.com:389 Priority:0 Weight:0");
responseList = response.AnswerRecords.SRV
.OrderBy(r => r.Priority)
.ThenByDescending(r => r.Weight)
.ToList();
Assert.Equal(responseList[0].ToString(), "foo.order.com:389 Priority:0 Weight:0");
Assert.Equal(responseList[1].ToString(), "foo.order.com:389 Priority:50 Weight:100");
Assert.Equal(responseList[2].ToString(), "foo.order.com:389 Priority:50 Weight:0");
Assert.Equal(responseList[3].ToString(), "foo.order.com:389 Priority:100 Weight:100");
Assert.Equal(responseList[4].ToString(), "foo.order.com:389 Priority:100 Weight:0");
}
/*
* From a DnsResponse get a string representing the answers it provided with the TTLs removed.
*/
public static string GetAnswersString(DnsResponse response)
{
if (response.HasError)
{
return(response.Error.Code.ToString()); //TODO: Might be nice to make these prettier someday
}
var records = response.QueryResponse.Answers;
if (records.Count == 0)
{
return("Empty");
}
List <string> recordStrings = new List <string>();
foreach (var record in records)
{
var recordString = record.ToString();
var ttlStart = recordString.IndexOf(' ');
var ttlEnd = recordString.IndexOf(' ', ttlStart + 1);
recordString = recordString.Remove(ttlStart, ttlEnd - ttlStart);
recordStrings.Add(recordString);
}
recordStrings.Sort();
return(string.Join(System.Environment.NewLine, recordStrings));
}
public void RequestResponse(IDnsContext context, ushort maxBufferLength)
{
if (context == null)
{
throw new ArgumentNullException();
}
try
{
//
// If we fail at parsing or receiving the request, then any exceptions will get logged and
// the socket will be silently closed
//
context.ReceiveRequest();
DnsResponse response = this.ProcessRequest(context.DnsBuffer);
if (response != null)
{
this.Serialize(response, context.DnsBuffer, maxBufferLength);
context.SendResponse();
}
}
catch (IndexOutOfRangeException)
{
// Valid exception thrown during processing when bad requests are sent...
// We won't dignify bad requests with a response
}
catch (DnsServerException)
{
// Valid exception thrown during processing when bad requests are sent...
// We won't dignify bad requests with a response
}
}
internal DnsClientResponse(DnsClientRequest request, DnsResponse response)
{
Request = request;
message = response.ToArray();
this.response = response;
}
private void Resolve(DnsRequest request)
{
DnsResponse matches = m_client.Resolve(request);
Assert.NotNull(matches);
Assert.True(matches.HasAnswerRecords, string.Format("{0}:{1}", request.Question.Type, request.Question.Domain));
}
/// <summary>
/// Look up a DNS SRV record, returning the best host and port number to connect to.
/// </summary>
/// <param name="prefix">The SRV prefix, ending with a dot. Example: "_xmpp-client._tcp."</param>
/// <param name="domain">The domain to check</param>
/// <param name="host">The host name to connect to</param>
/// <param name="port">The port number to connect to</param>
public static void LookupSRV(string prefix, string domain, ref string host, ref int port)
{
if (prefix == null)
{
throw new ArgumentNullException("prefix");
}
if (domain == null)
{
throw new ArgumentNullException("domain");
}
if (!prefix.EndsWith("."))
{
throw new ArgumentOutOfRangeException("Prefix must end in '.'", "prefix");
}
try
{
SRVRecord record;
DnsRequest request = new DnsRequest(prefix + domain);
DnsResponse response = request.GetResponse(DnsRecordType.SRV);
record = PickSRV(response.SRVRecords);
host = record.NameNext;
port = record.Port;
Debug.WriteLine(string.Format("SRV found: {0}:{1}", host, port));
}
catch
{
host = domain;
}
}
public async Task DoesNotAccessOrgDmarcRecordWhenOrgDomain()
{
string[] records = { "v=DMARC1;p=reject;adkim=s;aspf=s ..." };
string orgDomain = "def.gov.uk";
string domain = "abc.def.gov.uk";
Response domainDnsQueryResponse = CreateRecord(domain, records, RCode.NXDomain);
Response orgDomainDnsQueryResponse = CreateRecord(domain, records);
OrganisationalDomain organisationalDomain = new OrganisationalDomain(orgDomain, orgDomain);
A.CallTo(() => _dnsResolver.GetRecord($"_dmarc.{domain}", A <QType> ._))
.Returns(Task.FromResult(domainDnsQueryResponse));
A.CallTo(() => _dnsResolver.GetRecord($"_dmarc.{orgDomain}", A <QType> ._))
.Returns(Task.FromResult(orgDomainDnsQueryResponse));
A.CallTo(() => _organisationalDomainProvider.GetOrganisationalDomain(A <string> ._))
.Returns(Task.FromResult(organisationalDomain));
DnsResponse dmarcRecords = await _dmarcRecordDnsClient.GetRecord(domain);
Assert.That(dmarcRecords.Records.Count, Is.EqualTo(1));
Assert.That(((DmarcRecordInfo)dmarcRecords.Records[0]).Record, Is.EqualTo(records[0]));
A.CallTo(() => _organisationalDomainProvider.GetOrganisationalDomain(A <string> ._)).WithAnyArguments()
.MustHaveHappenedOnceExactly();
A.CallTo(() => _dnsResolver.GetRecord(A <string> ._, A <QType> ._)).WithAnyArguments()
.MustHaveHappenedOnceExactly();
}
public void ThreadProc(object state)
{
IEnumerable <string> domains = (IEnumerable <string>)state;
using (DnsClient client = m_server.CreateClient())
{
client.UseUDPFirst = m_udp;
client.Timeout = m_timeout;
foreach (string domain in domains)
{
try
{
DnsResponse response = client.Resolve(new DnsRequest(m_type, domain));
if (response.IsSuccess && response.HasAnswerRecords)
{
m_success++;
}
else
{
m_failure++;
}
}
catch
{
m_failure++;
}
}
}
}
public void ResolveVerifyTTLUpdate()
{
using (DnsClient client = s_authoritativeResolverServer.CreateClient())
{
DnsResponse response = client.Resolve(new DnsRequest(new DnsQuestion("direct.hisp.com", DnsStandard.RecordType.ANAME)));
Thread.Sleep(2500);
DnsResponse response2 = client.Resolve(new DnsRequest(new DnsQuestion("direct.hisp.com", DnsStandard.RecordType.ANAME)));
for (int i = 0; i < response.AnswerRecords.Count; i++)
{
Assert.True(response.AnswerRecords[i].TTL > response2.AnswerRecords[i].TTL);
}
for (int i = 0; i < response.AdditionalRecords.Count; i++)
{
Assert.True(response.AdditionalRecords[i].TTL > response2.AdditionalRecords[i].TTL);
}
for (int i = 0; i < response.NameServerRecords.Count; i++)
{
Assert.True(response.NameServerRecords[i].TTL > response2.NameServerRecords[i].TTL);
}
}
}
/// <summary>
/// Get an empty error response with the given status code
/// </summary>
/// <param name="query"></param>
/// <param name="statusCode"></param>
/// <returns></returns>
private static DnsResponse GetErrorResponse(DnsQuery query, DnsQueryStatusCode statusCode)
{
var response = new DnsResponse(query, null);
response.StatusCode = statusCode;
return(response);
}
public DnsResourceRecord Receive()
{
DnsBuffer responseBuffer = this.ReceiveBuffer();
DnsResponse response = new DnsResponse(responseBuffer.CreateReader());
Assert.True(response.AnswerRecords.Count != 0);
return(response.AnswerRecords[0]);
}
public void TestNotSupported(string domain, DnsStandard.RecordType type, bool useUDP)
{
DnsClient client = TestServer.Default.CreateClient();
client.UseUDPFirst = !useUDP;
DnsResponse response = client.Resolve(new DnsRequest(type, domain));
Assert.True(!response.IsSuccess);
}
DnsResponse ProcessResponse(DnsResponse response)
{
if (!response.HasAnyRecords)
{
response = null; // This will cause the server to return a NameError
}
return(response);
}
public void DnsSerialization_SOA_Response()
{
// Response packet captured for:
//
// nslookup -type=soa lilltek.com.
const string raw =
@"
00 07 81 80 00 01
00 00 00 01 00 00 07 6C 69 6C 6C 74 65 6B 03 63
6F 6D 00 00 06 00 01 C0 0C 00 06 00 01 00 00 2A
30 00 39 06 70 61 72 6B 31 39 0C 73 65 63 75 72
65 73 65 72 76 65 72 03 6E 65 74 00 03 64 6E 73
05 6A 6F 6D 61 78 C0 3D 77 82 0C F4 00 00 70 80
00 00 1C 20 00 09 3A 80 00 01 51 80
";
byte[] packet = Helper.FromHex(raw);
DnsResponse message;
SOA_RR soa_rr;
// Test parsing
message = new DnsResponse();
Assert.IsTrue(message.ParsePacket(packet, packet.Length));
Assert.AreEqual(DnsOpcode.QUERY, message.Opcode);
Assert.AreEqual(DnsQClass.IN, message.QClass);
Assert.AreEqual(DnsQType.SOA, message.QType);
Assert.AreEqual(DnsFlag.RCODE_OK, message.RCode);
Assert.AreEqual("lilltek.com.", message.QName);
Assert.IsTrue((message.Flags & DnsFlag.QR) != 0);
Assert.IsTrue((message.Flags & DnsFlag.TC) == 0);
Assert.IsTrue((message.Flags & DnsFlag.RD) != 0);
Assert.IsTrue((message.Flags & DnsFlag.RA) != 0);
Assert.AreEqual(0, message.Answers.Count);
Assert.AreEqual(1, message.Authorities.Count);
Assert.AreEqual(DnsRRType.SOA, message.Authorities[0].RRType);
soa_rr = (SOA_RR)message.Authorities[0];
Assert.AreEqual("lilltek.com.", soa_rr.RName);
Assert.AreEqual(DnsRRType.SOA, soa_rr.RRType);
Assert.AreEqual(DnsQClass.IN, soa_rr.QClass);
Assert.AreEqual(10800, soa_rr.TTL);
Assert.AreEqual("park19.secureserver.net.", soa_rr.Primary);
Assert.AreEqual("dns.jomax.net.", soa_rr.AdminEmail);
Assert.AreEqual((uint)2005011700, soa_rr.Serial);
Assert.AreEqual((uint)28800, soa_rr.Refresh);
Assert.AreEqual((uint)7200, soa_rr.Retry);
Assert.AreEqual((uint)604800, soa_rr.Expire);
Assert.AreEqual((uint)86400, soa_rr.Minimum);
// Test rendering
CollectionAssert.AreEqual(packet, Serialize(message));
}
public void DnsResolver_Multiple_Lookup()
{
// This test issues simultanious A queries for the 13
// global name servers and then verifies that the DnsResolver
// was able to correctly correlate the responses to the
// requests.
IPAddress dns = GetDns();
string[] gtld = new string[] {
"a.gtld-servers.net.",
"b.gtld-servers.net.",
"c.gtld-servers.net.",
"d.gtld-servers.net.",
"e.gtld-servers.net.",
"f.gtld-servers.net.",
"g.gtld-servers.net.",
"h.gtld-servers.net.",
"i.gtld-servers.net.",
"j.gtld-servers.net.",
"k.gtld-servers.net.",
"l.gtld-servers.net.",
"m.gtld-servers.net.",
};
DnsRequest[] requests = new DnsRequest[gtld.Length];
DnsResponse[] responses = new DnsResponse[gtld.Length];
IAsyncResult[] rgAR = new IAsyncResult[gtld.Length];
for (int j = 0; j < 10; j++)
{
// Repeat the test 10 times just for fun
for (int i = 0; i < gtld.Length; i++)
{
requests[i] = new DnsRequest(DnsFlag.RD, gtld[i], DnsQType.A);
}
for (int i = 0; i < gtld.Length; i++)
{
rgAR[i] = DnsResolver.BeginQuery(dns, requests[i], timeout, null, null);
}
for (int i = 0; i < gtld.Length; i++)
{
responses[i] = DnsResolver.EndQuery(rgAR[i]);
}
for (int i = 0; i < gtld.Length; i++)
{
Assert.AreEqual(requests[i].QID, responses[i].QID);
Assert.AreEqual(requests[i].QName, responses[i].QName);
}
}
}
/// <summary>
/// processes a CERT Question, populated the response with any matching results pulled from the database store
/// </summary>
/// <param name="response">DnsResponse instance containing information about the question that will
/// have any corresponding answer records populated upon return</param>
void ProcessCERTQuestion(DnsResponse response)
{
using (RecordRetrievalServiceClient client = m_recordRetrievalServiceSettings.CreateRecordRetrievalClient())
{
Certificate[] certs = client.GetCertificatesForOwner(response.Question.Domain);
foreach (Certificate cert in certs)
{
response.AnswerRecords.Add(new CertRecord(new DnsX509Cert(cert.Data)));
}
}
}
/// <summary>
/// processes a ANAME Question, populated the response with any matching results pulled from the database store
/// </summary>
/// <param name="response">DnsResponse instance containing information about the question that will
/// have any corresponding answer records populated upon return</param>
protected void ProcessANAMEQuestion(DnsResponse response)
{
using (RecordRetrievalServiceClient client = m_recordRetrievalServiceSettings.CreateRecordRetrievalClient())
{
client.GetANAMERecords(response.Question.Domain, response.AnswerRecords);
if (!response.HasAnswerRecords)
{
client.GetCNAMERecords(response.Question.Domain, response.AnswerRecords);
}
}
}
protected void Serialize(DnsResponse response, DnsBuffer buffer, int maxResponse)
{
buffer.Clear();
response.Serialize(buffer);
if (buffer.Count > maxResponse)
{
response.Truncate();
buffer.Clear();
response.Serialize(buffer);
}
}
void OnTcpResponse(DnsResponse response)
{
if (m_logger.IsTraceEnabled)
{
m_logger.Debug(this.Summarize("TCP", response));
}
else if (m_logger.IsDebugEnabled)
{
m_logger.Info("TCP Response {0} {1}", response.Question.Domain, response.Header.ResponseCode);
}
}
private DnsResponse CreateResponse(DnsRequest request, IPAddress address)
{
if (request == null || address == null)
{
return null;
}
DnsResponse response = CreateResponse(request.QueryID);
response.Questions.Add(new ResourceRecord(request.Domain, request.QueryType, request.QueryClass, 127));
response.Answers.Add(new Address(request.Domain, request.QueryType, request.QueryClass, 127, address.ToString()));
return response;
}
/// <summary>
/// Get an empty error response with the given status code
/// </summary>
/// <param name="query"></param>
/// <param name="statusCode"></param>
/// <returns></returns>
private static DnsResponse GetErrorResponse(DnsQuery query, DnsQueryStatusCode statusCode)
{
var response = new DnsResponse(query, null);
response.StatusCode = statusCode;
return response;
}
bool RetrieveDnsResponse(UdpSocket socket, UInt16 transactionID, out DnsResponse dnsResponse, Int64 timeoutInMachineTicks)
{
byte[] dnsFrameBuffer = new byte[DNS_FRAME_BUFFER_LENGTH];
while (timeoutInMachineTicks > Microsoft.SPOT.Hardware.Utility.GetMachineTime().Ticks)
{
Int32 bytesReceived = socket.Receive(dnsFrameBuffer, 0, dnsFrameBuffer.Length, 0, timeoutInMachineTicks);
if (bytesReceived == 0) // timeout
{
break;
}
/* parse our DNS response */
Int32 bufferIndex = 0;
// verify that the transaction ID matches
UInt16 verifyTransactionID = (UInt16)(
(UInt16)(dnsFrameBuffer[bufferIndex++] << 8) +
(UInt16)(dnsFrameBuffer[bufferIndex++])
);
if (transactionID != verifyTransactionID)
continue; /* filter out this DHCP frame */
// Flags
UInt16 flags = (UInt16)(
(UInt16)(dnsFrameBuffer[bufferIndex++] << 8) +
(UInt16)(dnsFrameBuffer[bufferIndex++])
);
DnsResponseCode responseCode = (DnsResponseCode)(flags & 0x0F);
// Query Count
UInt16 queryCount = (UInt16)(
(UInt16)(dnsFrameBuffer[bufferIndex++] << 8) +
(UInt16)(dnsFrameBuffer[bufferIndex++])
);
// Answer Record Count
UInt16 answerRecordCount = (UInt16)(
(UInt16)(dnsFrameBuffer[bufferIndex++] << 8) +
(UInt16)(dnsFrameBuffer[bufferIndex++])
);
// Authority Record Count
UInt16 authorityRecordCount = (UInt16)(
(UInt16)(dnsFrameBuffer[bufferIndex++] << 8) +
(UInt16)(dnsFrameBuffer[bufferIndex++])
);
// Additional Information Record Count
UInt16 additionalInformationRecordCount = (UInt16)(
(UInt16)(dnsFrameBuffer[bufferIndex++] << 8) +
(UInt16)(dnsFrameBuffer[bufferIndex++])
);
/* parse our query records */
string queryName = "";
DnsRecordType queryType = (DnsRecordType)0;
for (int iRecord = 0; iRecord < queryCount; iRecord++)
{
// Query Name
bufferIndex += ParseDnsName(dnsFrameBuffer, bufferIndex, out queryName);
queryType = (DnsRecordType)(
(UInt16)(dnsFrameBuffer[bufferIndex++] << 8) +
(UInt16)(dnsFrameBuffer[bufferIndex++])
);
UInt16 queryClass = (UInt16)(
(UInt16)(dnsFrameBuffer[bufferIndex++] << 8) +
(UInt16)(dnsFrameBuffer[bufferIndex++])
);
if (queryClass != DNS_RECORD_CLASS_INTERNET)
continue; /* filter out the current query */
}
/* parse our answer records */
DnsResourceRecord[] answerRecords = new DnsResourceRecord[answerRecordCount];
for (int iRecord = 0; iRecord < answerRecordCount; iRecord++)
{
// store answer record
bufferIndex += ParseResourceRecord(dnsFrameBuffer, bufferIndex, out answerRecords[iRecord]);
}
/* parse our authority records */
DnsResourceRecord[] authorityRecords = new DnsResourceRecord[authorityRecordCount];
for (int iRecord = 0; iRecord < authorityRecordCount; iRecord++)
{
// store authority record
bufferIndex += ParseResourceRecord(dnsFrameBuffer, bufferIndex, out authorityRecords[iRecord]);
}
/* parse our authority records */
DnsResourceRecord[] additionalInformationRecords = new DnsResourceRecord[additionalInformationRecordCount];
for (int iRecord = 0; iRecord < additionalInformationRecordCount; iRecord++)
{
// store authority record
bufferIndex += ParseResourceRecord(dnsFrameBuffer, bufferIndex, out additionalInformationRecords[iRecord]);
}
dnsResponse = new DnsResponse(responseCode, queryType, queryName, answerRecords, authorityRecords, additionalInformationRecords);
return true;
}
// if we did not receive a message before timeout, return false.
dnsResponse = null;
return false;
}
void OnReceive (IAsyncResult ares)
{
if (disposed)
return;
int nread = 0;
EndPoint remote_ep = client.RemoteEndPoint;
try {
nread = client.EndReceive (ares);
} catch (Exception e) {
Console.Error.WriteLine (e);
}
BeginReceive ();
byte [] buffer = (byte []) ares.AsyncState;
if (nread > 12) {
DnsResponse response = new DnsResponse (buffer, nread);
int id = response.Header.ID;
SimpleResolverEventArgs args = null;
lock (queries) {
if (queries.TryGetValue (id, out args)) {
queries.Remove (id);
}
}
if (args != null) {
Timer t = args.Timer;
if (t != null)
t.Change (Timeout.Infinite, Timeout.Infinite);
try {
ProcessResponse (args, response, remote_ep);
} catch (Exception e) {
args.ResolverError = (ResolverError) (-1);
args.ErrorMessage = e.Message;
}
IPHostEntry entry = args.HostEntry;
if (args.ResolverError != 0 && args.PTRAddress != null && entry != null && entry.HostName != null) {
args.PTRAddress = null;
SendAQuery (args, entry.HostName, true);
args.Timer.Change (5000, Timeout.Infinite);
} else {
args.OnCompleted (this);
}
}
}
}
void ProcessResponse (SimpleResolverEventArgs args, DnsResponse response, EndPoint server_ep)
{
DnsRCode status = response.Header.RCode;
if (status != 0) {
if (args.PTRAddress != null) {
// PTR query failed -> no error, we have the IP
return;
}
args.ResolverError = (ResolverError) status;
return;
}
// TODO: verify IP of the server is in our list and the same one that got the query
IPEndPoint ep = (IPEndPoint) server_ep;
if (ep.Port != 53) {
args.ResolverError = ResolverError.ResponseHeaderError;
args.ErrorMessage = "Port";
return;
}
DnsHeader header = response.Header;
if (!header.IsQuery) {
args.ResolverError = ResolverError.ResponseHeaderError;
args.ErrorMessage = "IsQuery";
return;
}
// TODO: handle Truncation. Retry with bigger buffer?
if (header.QuestionCount > 1) {
args.ResolverError = ResolverError.ResponseHeaderError;
args.ErrorMessage = "QuestionCount";
return;
}
ReadOnlyCollection<DnsQuestion> q = response.GetQuestions ();
if (q.Count != 1) {
args.ResolverError = ResolverError.ResponseHeaderError;
args.ErrorMessage = "QuestionCount 2";
return;
}
DnsQuestion question = q [0];
/* The answer might have dot at the end, etc...
if (String.Compare (question.Name, args.HostName) != 0) {
args.ResolverError = ResolverError.ResponseHeaderError;
args.ErrorMessage = "HostName - " + question.Name + " != " + args.HostName;
return;
}
*/
DnsQType t = question.Type;
if (t != DnsQType.A && t != DnsQType.AAAA && t != DnsQType.PTR) {
args.ResolverError = ResolverError.ResponseHeaderError;
args.ErrorMessage = "QType " + question.Type;
return;
}
if (question.Class != DnsQClass.IN) {
args.ResolverError = ResolverError.ResponseHeaderError;
args.ErrorMessage = "QClass " + question.Class;
return;
}
ReadOnlyCollection<DnsResourceRecord> records = response.GetAnswers ();
if (records.Count == 0) {
if (args.PTRAddress != null) {
// PTR query failed -> no error
return;
}
args.ResolverError = ResolverError.NameError; // is this ok?
args.ErrorMessage = "NoAnswers";
return;
}
List<string> aliases = null;
List<IPAddress> addresses = null;
foreach (DnsResourceRecord r in records) {
if (r.Class != DnsClass.IN)
continue;
if (r.Type == DnsType.A || r.Type == DnsType.AAAA) {
if (addresses == null)
addresses = new List<IPAddress> ();
addresses.Add (((DnsResourceRecordIPAddress) r).Address);
} else if (r.Type == DnsType.CNAME) {
if (aliases == null)
aliases = new List<string> ();
aliases.Add (((DnsResourceRecordCName) r).CName);
} else if (r.Type == DnsType.PTR) {
args.HostEntry.HostName = ((DnsResourceRecordPTR) r).DName;
args.HostEntry.Aliases = aliases == null ? EmptyStrings : aliases.ToArray ();
args.HostEntry.AddressList = EmptyAddresses;
return;
}
}
IPHostEntry entry = args.HostEntry ?? new IPHostEntry ();
if (entry.HostName == null && aliases != null && aliases.Count > 0) {
entry.HostName = aliases [0];
aliases.RemoveAt (0);
}
entry.Aliases = aliases == null ? EmptyStrings : aliases.ToArray ();
entry.AddressList = addresses == null ? EmptyAddresses : addresses.ToArray ();
args.HostEntry = entry;
if ((question.Type == DnsQType.A || question.Type == DnsQType.AAAA) && entry.AddressList == EmptyAddresses) {
args.ResolverError = ResolverError.NameError;
args.ErrorMessage = "No addresses in response";
} else if (question.Type == DnsQType.PTR && entry.HostName == null) {
args.ResolverError = ResolverError.NameError;
args.ErrorMessage = "No PTR in response";
}
}
bool SendDnsQueryAndWaitForResponse(UInt32 dnsServerIPAddress, DnsRecordType recordType, string name, out DnsResponse dnsResponse, Int64 timeoutInMachineTicks)
{
// obtain an exclusive handle to the reserved socket
int socketHandle = _ipv4Layer.CreateSocket(IPv4Layer.ProtocolType.Udp, timeoutInMachineTicks, true);
// instantiate the reserved socket
UdpSocket socket = (UdpSocket)_ipv4Layer.GetSocket(socketHandle);
try
{
// create DNS request header
byte[] dnsRequestBuffer = new byte[DNS_FRAME_BUFFER_LENGTH];
int bufferIndex = 0;
/* Transaction ID */
UInt16 transactionID = _nextTransactionID++;
dnsRequestBuffer[bufferIndex++] = (byte)((transactionID >> 8) & 0xFF);
dnsRequestBuffer[bufferIndex++] = (byte)(transactionID & 0xFF);
/* Flags (including OpCode and RCODE) */
DnsMessageFlagsFlags flags = 0;
/* QR = 0 (query)
* OpCode = 0 (standard query/response)
* RD = 1 (recursion desired) */
flags |= DnsMessageFlagsFlags.RecursionDesired;
dnsRequestBuffer[bufferIndex++] |= (byte)(((UInt16)flags >> 8) & 0xFF);
dnsRequestBuffer[bufferIndex++] |= (byte)((UInt16)flags & 0xFF);
/* Query Count */
UInt16 queryCount = 1;
dnsRequestBuffer[bufferIndex++] = (byte)((queryCount >> 8) & 0xFF);
dnsRequestBuffer[bufferIndex++] = (byte)(queryCount & 0xFF);
/* Answer Count */
// skip bytes 6-7
bufferIndex += 2;
/* Authority Record Count */
// skip bytes 8-9
bufferIndex += 2;
/* Additional Information Count */
// skip bytes 10-11
bufferIndex += 2;
// create dns question (query)
// Query Name
Int32 namePosition = 0;
while (true)
{
Int32 labelLength = name.IndexOf('.', namePosition) - namePosition;
if (labelLength < 0)
{
bufferIndex++;
break;
}
dnsRequestBuffer[bufferIndex++] = (byte)labelLength;
Int32 labelLengthVerify = System.Text.Encoding.UTF8.GetBytes(name, namePosition, labelLength, dnsRequestBuffer, bufferIndex);
// if the label was not decoded as 8-bit characters, throw an exception; international punycode-encoded domains are not supported.
if (labelLengthVerify != labelLength)
throw new ArgumentException();
namePosition += labelLength + 1;
bufferIndex += labelLength;
}
// Query Type
dnsRequestBuffer[bufferIndex++] = (byte)((((UInt16)recordType) >> 8) & 0xFF);
dnsRequestBuffer[bufferIndex++] = (byte)(((UInt16)recordType) & 0xFF);
// Query Class
UInt16 queryClass = DNS_RECORD_CLASS_INTERNET;
dnsRequestBuffer[bufferIndex++] = (byte)((queryClass >> 8) & 0xFF);
dnsRequestBuffer[bufferIndex++] = (byte)(queryClass & 0xFF);
/* NOTE: this implementation queries the primary DNS address */
// send DNS request
socket.SendTo(dnsRequestBuffer, 0, bufferIndex, 0, timeoutInMachineTicks, dnsServerIPAddress, DNS_SERVER_PORT);
// wait for DNS response
bool success = RetrieveDnsResponse(socket, transactionID, out dnsResponse, timeoutInMachineTicks);
if (success)
{
return true;
}
}
finally
{
// close the reserved socket
_ipv4Layer.CloseSocket(socketHandle);
}
return false; /* could not retrieve DNS response */
}
