internal int Init(DnsPacket packet, int offset)
{
name = packet.ReadName(ref offset);
type = (DnsQType)packet.ReadUInt16(ref offset);
_class = (DnsQClass)packet.ReadUInt16(ref offset);
return(offset);
}
internal int Init (DnsPacket packet, int offset)
{
name = packet.ReadName (ref offset);
type = (DnsQType) packet.ReadUInt16 (ref offset);
_class = (DnsQClass) packet.ReadUInt16 (ref offset);
return offset;
}
public DnsQuery(string name, DnsQType qtype, DnsQClass qclass)
{
if (String.IsNullOrEmpty(name))
{
throw new ArgumentNullException("name");
}
int length = DnsUtil.GetEncodedLength(name);
if (length == -1)
{
throw new ArgumentException("Invalid DNS name", "name");
}
length += 12 + 2 + 2; // Header + qtype + qclass
packet = new byte [length];
header = new DnsHeader(packet, 0);
position = 12;
WriteDnsName(name);
WriteUInt16((ushort)qtype);
WriteUInt16((ushort)qclass);
Header.QuestionCount = 1;
Header.IsQuery = true;
Header.RecursionDesired = true;
}
/// <summary>
/// Shallow copies the data members from the source message passed
/// to this instance.
/// </summary>
/// <param name="source">The source message.</param>
protected void CopyFrom(DnsMessage source)
{
this.qid = source.qid;
this.flags = source.flags;
this.qname = source.qname;
this.qtype = source.qtype;
this.qclass = source.qclass;
this.answers = source.answers;
this.authorities = source.authorities;
this.additional = source.additional;
}
private Dictionary <string, int> namePtrs; // Set of existing name compression pointers
/// <summary>
/// This constructor initializes the message fields to default values.
/// </summary>
public DnsMessage()
{
this.qid = 0;
this.flags = 0;
this.qname = null;
this.qtype = DnsQType.NULL;
this.qclass = DnsQClass.IN;
this.answers = null;
this.authorities = null;
this.additional = null;
this.namePtrs = null;
}
/// <summary>
/// Connstructs a typical Internet class DNS request.
/// </summary>
/// <param name="flags">Additional flag bits (the QR and OPCODE sections will be set automatically).</param>
/// <param name="qname">The query name.</param>
/// <param name="qtype">The query type.</param>
/// <remarks>
/// <para>
/// By default, this constructor initializes the OPCODE section of the message flags to
/// <see cref="DnsOpcode.QUERY" />, the query ID to zero, and the query class to
/// <see cref="DnsQClass.IN" />. These properties can be modified directly after
/// construction if necessary. Note that the <see cref="DnsResolver" /> class
/// handles the assignment of a unique query ID so it generally not necessary
/// to explicitly set this property.
/// </para>
/// </remarks>
public DnsRequest(DnsFlag flags, string qname, DnsQType qtype)
: base()
{
if (!qname.EndsWith("."))
{
throw new ArgumentException("Domain names must end with [.]", "qname");
}
this.Flags = flags;
this.QName = qname;
this.QType = qtype;
this.QClass = DnsQClass.IN;
}
public DnsQuery (string name, DnsQType qtype, DnsQClass qclass)
{
if (String.IsNullOrEmpty (name))
throw new ArgumentNullException ("name");
int length = DnsUtil.GetEncodedLength (name);
if (length == -1)
throw new ArgumentException ("Invalid DNS name", "name");
length += 12 + 2 + 2; // Header + qtype + qclass
packet = new byte [length];
header = new DnsHeader (packet, 0);
position = 12;
WriteDnsName (name);
WriteUInt16 ((ushort) qtype);
WriteUInt16 ((ushort) qclass);
Header.QuestionCount = 1;
Header.IsQuery = true;
Header.RecursionDesired = true;
}
static DnsQuery GetQuery (string host, DnsQType q, DnsQClass c)
{
return new DnsQuery (host, q, c);
}
/// <summary>
/// Gets DNSType
/// </summary>
/// <param name="uri"></param>
/// <param name="type"></param>
/// <returns></returns>
public string GetDnsRecord(string uri, DnsQType type)
{
string result = string.Empty;
Request req = new Request();
Question q = new Question(uri, type, DnsClass.IN);
req.AddQuestion(q);
try
{
Response r = Resolver.Lookup(req, GetDnsServer());
foreach (Answer a in r.Answers)
{
switch (a.Type)
{
case DnsType.A:
result += string.Format("{0} has IPv4 address {1} (ttl: {2}){3}",
a.Domain, a.Record, a.Ttl, Environment.NewLine);
break;
case DnsType.NS:
result += string.Format("{0} nameserver {1}; ttl: {2}{3}",
a.Domain, a.Record, a.Ttl, Environment.NewLine);
break;
case DnsType.CNAME:
result += string.Format("{0} alias of {1} (ttl: {2}){3}",
a.Domain, a.Record, a.Ttl, Environment.NewLine);
break;
case DnsType.SOA:
result += string.Format("typeid:\t\t{0}\nttl:\t\t{1}\ndata:\t\t{2}\ndomain:\t\t{3}\nserial:\t\t{4}\nrefresh:\t\t{5}\nretry:" +
"\t\t{6}\nexpiry:\t\t{7}\nminttl:\t\t{8}\nresponsible:\t{9}\n\n", a.Type, a.Ttl,
((Bdev.Net.Dns.Records.SoaRecord)a.Record).PrimaryNameServer, uri,
((Bdev.Net.Dns.Records.SoaRecord)a.Record).Serial, ((Bdev.Net.Dns.Records.SoaRecord)a.Record).Refresh,
((Bdev.Net.Dns.Records.SoaRecord)a.Record).Retry, ((Bdev.Net.Dns.Records.SoaRecord)a.Record).Expire,
((Bdev.Net.Dns.Records.SoaRecord)a.Record).DefaultTtl, ((Bdev.Net.Dns.Records.SoaRecord)a.Record).ResponsibleMailAddress);
break;
case DnsType.MX:
result += string.Format("\n{0} mailserver {1} (pri={2}); ttl: {3}", a.Domain,
((Bdev.Net.Dns.Records.MXRecord)a.Record).DomainName, ((Bdev.Net.Dns.Records.MXRecord)a.Record).Preference, a.Ttl);
break;
case DnsType.TXT:
result += string.Format("{0}:\t{1} (ttl: {2}){3}",
a.Domain, a.Record, a.Ttl, Environment.NewLine);
break;
case DnsType.AAAA:
result += string.Format("{0} has IPv6 address {1} (ttl: {2}){3}",
a.Domain, a.Record, a.Ttl, Environment.NewLine);
break;
case DnsType.SRV:
result += string.Format("{0}:\t{1} (ttl: {2}){3}",
a.Domain, a.Record, a.Ttl, Environment.NewLine);
break;
}
}
}
catch (Exception ex)
{
if (type == DnsQType.A)
{
return(GetDnsRecord(uri, DnsQType.CNAME));
}
return(uri + ": " + ex.Message + Environment.NewLine);
}
return(result);
}
/// <summary>
/// Compares the message's query type and qname to the parameters passed.
/// </summary>
/// <param name="qtype">The query type to be matched.</param>
/// <param name="qname">The query name to be matched.</param>
/// <returns><c>true</c> if both parameters match the values stored in the message.</returns>
public bool Match(DnsQType qtype, string qname)
{
return(this.QType == qtype && String.Compare(this.QName, qname, true) == 0);
}
/// <summary>
/// This method parses the raw DNS message packet passed and initializes
/// the message properties.
/// </summary>
/// <param name="packet">The raw DNS packet received.</param>
/// <param name="cbPacket">Number of bytes in that packet.</param>
/// <returns>True on success.</returns>
public bool ParsePacket(byte[] packet, int cbPacket)
{
uint qdCount;
uint anCount;
uint nsCount;
uint arCount;
int pos;
// Read the message header
pos = 0;
this.qid = (ushort)Helper.ReadInt16(packet, ref pos); if (pos > cbPacket)
{
return(false);
}
this.flags = (DnsFlag)Helper.ReadInt16(packet, ref pos); if (pos > cbPacket)
{
return(false);
}
qdCount = (ushort)Helper.ReadInt16(packet, ref pos); if (pos > cbPacket)
{
return(false);
}
anCount = (ushort)Helper.ReadInt16(packet, ref pos); if (pos > cbPacket)
{
return(false);
}
nsCount = (ushort)Helper.ReadInt16(packet, ref pos); if (pos > cbPacket)
{
return(false);
}
arCount = (ushort)Helper.ReadInt16(packet, ref pos); if (pos > cbPacket)
{
return(false);
}
Assertion.Test(pos == 12);
// Check for unsupported packets
if ((this.flags & DnsFlag.TC) != 0) // truncation bit is set
{
return(false);
}
if (this.Opcode != DnsOpcode.QUERY) // only accept standard queries
{
return(false);
}
if (qdCount != 1) // only supporting one question
{
return(false);
}
// Parse the question
if (!ReadName(packet, ref pos, out this.qname))
{
return(false);
}
if (pos > cbPacket)
{
return(false);
}
this.qtype = (DnsQType)Helper.ReadInt16(packet, ref pos); if (pos > cbPacket)
{
return(false);
}
this.qclass = (DnsQClass)Helper.ReadInt16(packet, ref pos); if (pos > cbPacket)
{
return(false);
}
// We're only going to accept Internet queries
if (this.qclass != DnsQClass.IN)
{
return(false);
}
// Parse the answer records
for (int i = 0; i < anCount; i++)
{
var rr = DnsRR.Parse(this, packet, ref pos);
if (rr == null || pos > cbPacket)
{
return(false);
}
this.Answers.Add(rr);
}
// Parse the authority records
for (int i = 0; i < nsCount; i++)
{
var rr = DnsRR.Parse(this, packet, ref pos);
if (rr == null || pos > cbPacket)
{
return(false);
}
this.Authorities.Add(rr);
}
// Parse the additional records
for (int i = 0; i < arCount; i++)
{
var rr = DnsRR.Parse(this, packet, ref pos);
if (rr == null || pos > cbPacket)
{
return(false);
}
this.Additional.Add(rr);
}
// $todo(jeff.lill):
//
// Delete this once we've figured out why the DNS server
// sometimes get requests with NULL QNAME properties.
if (this.QName == null)
{
var packetBytes = Helper.Extract(packet, cbPacket);
var hexDump = Helper.HexDump(packetBytes, 16, HexDumpOption.ShowAll);
var diagnostics = GetTraceDetails(IPAddress.Any);
var extendedLogInfo = new StringSysLogEntryExtension(diagnostics + "\r\n\r\nPacket:\r\n\r\n" + hexDump);
SysLog.LogWarning(extendedLogInfo, "DNS Packet with QNAME=NULL");
}
return(true);
}
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";
}
}
static DnsQuery GetQuery(string host, DnsQType q, DnsQClass c)
{
return(new DnsQuery(host, q, c));
}
