Merge pull request #42 from BornToBeRoot/DNS-Lookup

DNS Lookup added

Author: BornToBeRoot

Source/NETworkManager/3rdParty/Heijden.DNS/Header.cs

@@ -0,0 +1,351 @@
+using System;
+using System.IO;
+using System.Collections.Generic;
+using System.Net;
+using System.Text;
+
+namespace Heijden.DNS
+{
+	#region RFC specification
+	/*
+	4.1.1. Header section format
+
+	The header contains the following fields:
+
+										1  1  1  1  1  1
+		  0  1  2  3  4  5  6  7  8  9  0  1  2  3  4  5
+		+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
+		|                      ID                       |
+		+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
+		|QR|   Opcode  |AA|TC|RD|RA|   Z    |   RCODE   |
+		+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
+		|                    QDCOUNT                    |
+		+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
+		|                    ANCOUNT                    |
+		+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
+		|                    NSCOUNT                    |
+		+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
+		|                    ARCOUNT                    |
+		+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
+
+		where:
+
+		ID              A 16 bit identifier assigned by the program that
+						generates any kind of query.  This identifier is copied
+						the corresponding reply and can be used by the requester
+						to match up replies to outstanding queries.
+
+		QR              A one bit field that specifies whether this message is a
+						query (0), or a response (1).
+
+		OPCODE          A four bit field that specifies kind of query in this
+						message.  This value is set by the originator of a query
+						and copied into the response.  The values are:
+
+						0               a standard query (QUERY)
+
+						1               an inverse query (IQUERY)
+
+						2               a server status request (STATUS)
+
+						3-15            reserved for future use
+
+		AA              Authoritative Answer - this bit is valid in responses,
+						and specifies that the responding name server is an
+						authority for the domain name in question section.
+
+						Note that the contents of the answer section may have
+						multiple owner names because of aliases.  The AA bit
+						corresponds to the name which matches the query name, or
+						the first owner name in the answer section.
+
+		TC              TrunCation - specifies that this message was truncated
+						due to length greater than that permitted on the
+						transmission channel.
+
+		RD              Recursion Desired - this bit may be set in a query and
+						is copied into the response.  If RD is set, it directs
+						the name server to pursue the query recursively.
+						Recursive query support is optional.
+
+		RA              Recursion Available - this be is set or cleared in a
+						response, and denotes whether recursive query support is
+						available in the name server.
+
+		Z               Reserved for future use.  Must be zero in all queries
+						and responses.
+
+		RCODE           Response code - this 4 bit field is set as part of
+						responses.  The values have the following
+						interpretation:
+
+						0               No error condition
+
+						1               Format error - The name server was
+										unable to interpret the query.
+
+						2               Server failure - The name server was
+										unable to process this query due to a
+										problem with the name server.
+
+						3               Name Error - Meaningful only for
+										responses from an authoritative name
+										server, this code signifies that the
+										domain name referenced in the query does
+										not exist.
+
+						4               Not Implemented - The name server does
+										not support the requested kind of query.
+
+						5               Refused - The name server refuses to
+										perform the specified operation for
+										policy reasons.  For example, a name
+										server may not wish to provide the
+										information to the particular requester,
+										or a name server may not wish to perform
+										a particular operation (e.g., zone
+										transfer) for particular data.
+
+						6-15            Reserved for future use.
+
+		QDCOUNT         an unsigned 16 bit integer specifying the number of
+						entries in the question section.
+
+		ANCOUNT         an unsigned 16 bit integer specifying the number of
+						resource records in the answer section.
+
+		NSCOUNT         an unsigned 16 bit integer specifying the number of name
+						server resource records in the authority records
+						section.
+
+		ARCOUNT         an unsigned 16 bit integer specifying the number of
+						resource records in the additional records section.
+
+		*/
+	#endregion
+
+	public class Header
+	{
+		/// <summary>
+		/// An identifier assigned by the program
+		/// </summary>
+		public ushort ID;
+
+		// internal flag
+		private ushort Flags;
+
+		/// <summary>
+		/// the number of entries in the question section
+		/// </summary>
+		public ushort QDCOUNT;
+
+		/// <summary>
+		/// the number of resource records in the answer section
+		/// </summary>
+		public ushort ANCOUNT;
+
+		/// <summary>
+		/// the number of name server resource records in the authority records section
+		/// </summary>
+		public ushort NSCOUNT;
+
+		/// <summary>
+		/// the number of resource records in the additional records section
+		/// </summary>
+		public ushort ARCOUNT;
+
+		public Header()
+		{
+		}
+
+		public Header(RecordReader rr)
+		{
+			ID = rr.ReadUInt16();
+			Flags = rr.ReadUInt16();
+			QDCOUNT = rr.ReadUInt16();
+			ANCOUNT = rr.ReadUInt16();
+			NSCOUNT = rr.ReadUInt16();
+			ARCOUNT = rr.ReadUInt16();
+		}
+
+
+		private ushort SetBits(ushort oldValue, int position, int length, bool blnValue)
+		{
+			return SetBits(oldValue, position, length, blnValue ? (ushort)1 : (ushort)0);
+		}
+
+		private ushort SetBits(ushort oldValue, int position, int length, ushort newValue)
+		{
+			// sanity check
+			if (length <= 0 || position >= 16)
+				return oldValue;
+
+			// get some mask to put on
+			int mask = (2 << (length - 1)) - 1;
+
+			// clear out value
+			oldValue &= (ushort)~(mask << position);
+
+			// set new value
+			oldValue |= (ushort)((newValue & mask) << position);
+			return oldValue;
+		}
+
+		private ushort GetBits(ushort oldValue, int position, int length)
+		{
+			// sanity check
+			if (length <= 0 || position >= 16)
+				return 0;
+
+			// get some mask to put on
+			int mask = (2 << (length - 1)) - 1;
+
+			// shift down to get some value and mask it
+			return (ushort)((oldValue >> position) & mask);
+		}
+
+		/// <summary>
+		/// Represents the header as a byte array
+		/// </summary>
+		public byte[] Data
+		{
+			get
+			{
+				List<byte> data = new List<byte>();
+				data.AddRange(WriteShort(ID));
+				data.AddRange(WriteShort(Flags));
+				data.AddRange(WriteShort(QDCOUNT));
+				data.AddRange(WriteShort(ANCOUNT));
+				data.AddRange(WriteShort(NSCOUNT));
+				data.AddRange(WriteShort(ARCOUNT));
+				return data.ToArray();
+			}
+		}
+
+		private byte[] WriteShort(ushort sValue)
+		{
+			return BitConverter.GetBytes(IPAddress.HostToNetworkOrder((short)sValue));
+		}
+
+
+		/// <summary>
+		/// query (false), or a response (true)
+		/// </summary>
+		public bool QR
+		{
+			get
+			{
+				return GetBits(Flags, 15, 1) == 1;
+			}
+			set
+			{
+				Flags = SetBits(Flags, 15, 1, value);
+			}
+		}
+
+		/// <summary>
+		/// Specifies kind of query
+		/// </summary>
+		public OPCode OPCODE
+		{
+			get
+			{
+				return (OPCode)GetBits(Flags, 11, 4);
+			}
+			set
+			{
+				Flags = SetBits(Flags, 11, 4, (ushort)value);
+			}
+		}
+
+		/// <summary>
+		/// Authoritative Answer
+		/// </summary>
+		public bool AA
+		{
+			get
+			{
+				return GetBits(Flags, 10, 1) == 1;
+			}
+			set
+			{
+				Flags = SetBits(Flags, 10, 1, value);
+			}
+		}
+
+		/// <summary>
+		/// TrunCation
+		/// </summary>
+		public bool TC
+		{
+			get
+			{
+				return GetBits(Flags, 9, 1) == 1;
+			}
+			set
+			{
+				Flags = SetBits(Flags, 9, 1, value);
+			}
+		}
+
+		/// <summary>
+		/// Recursion Desired
+		/// </summary>
+		public bool RD
+		{
+			get
+			{
+				return GetBits(Flags, 8, 1) == 1;
+			}
+			set
+			{
+				Flags = SetBits(Flags, 8, 1, value);
+			}
+		}
+
+		/// <summary>
+		/// Recursion Available
+		/// </summary>
+		public bool RA
+		{
+			get
+			{
+				return GetBits(Flags, 7, 1) == 1;
+			}
+			set
+			{
+				Flags = SetBits(Flags, 7, 1, value);
+			}
+		}
+
+		/// <summary>
+		/// Reserved for future use
+		/// </summary>
+		public ushort Z
+		{
+			get
+			{
+				return GetBits(Flags, 4, 3);
+			}
+			set
+			{
+				Flags = SetBits(Flags, 4, 3, value);
+			}
+		}
+
+		/// <summary>
+		/// Response code
+		/// </summary>
+		public RCode RCODE
+		{
+			get
+			{
+				return (RCode)GetBits(Flags, 0, 4);
+			}
+			set
+			{
+				Flags = SetBits(Flags, 0, 4, (ushort)value);
+			}
+		}
+	}
+}