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;
}
private byte[] data; // Resource record data
/// <summary>
/// This constructor initializes an empty DNS resource
/// record.
/// </summary>
public DnsRR()
{
this.rrtype = DnsRRType.UNKNOWN;
this.rname = string.Empty;
this.qclass = DnsQClass.IN;
this.ttl = 0;
this.data = new byte[0];
}
/// <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>
/// This method parses the resource record from the packet beginning
/// at the offset passed.
/// </summary>
/// <param name="message">The message containing the record being parsed.</param>
/// <param name="packet">The packet buffer.</param>
/// <param name="offset">
/// The offset in the packet where the record is located.
/// This parameter will return set to the offset of the first
/// byte after the parsed record.
/// </param>
/// <returns>True on success.</returns>
public bool Read(DnsMessage message, byte[] packet, ref int offset)
{
if (!message.ReadName(packet, ref offset, out rname))
{
return(false);
}
rrtype = (DnsRRType)Helper.ReadInt16(packet, ref offset);
qclass = (DnsQClass)Helper.ReadInt16(packet, ref offset);
ttl = Helper.ReadInt32(packet, ref offset);
return(ReadData(message, packet, ref 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;
}
static DnsQuery GetQuery (string host, DnsQType q, DnsQClass c)
{
return new DnsQuery (host, q, c);
}
/// <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);
}
static DnsQuery GetQuery(string host, DnsQType q, DnsQClass c)
{
return(new DnsQuery(host, q, c));
}