134 lines
3.3 KiB
C#
134 lines
3.3 KiB
C#
//
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// Mono.Net.Dns.DnsPacket
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//
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// Authors:
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// Gonzalo Paniagua Javier (gonzalo.mono@gmail.com)
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//
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// Copyright 2011 Gonzalo Paniagua Javier
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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//
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using System;
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using System.Collections.Generic;
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using System.Text;
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using System.IO;
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namespace Mono.Net.Dns {
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abstract class DnsPacket {
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protected byte [] packet;
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protected int position;
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protected DnsHeader header;
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protected DnsPacket ()
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{
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// Caller has to initialize packet, position and header
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}
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protected DnsPacket (int length)
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: this (new byte [length], length)
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{
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}
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protected DnsPacket (byte [] buffer, int length)
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{
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if (buffer == null)
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throw new ArgumentNullException("buffer");
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if (length <= 0)
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throw new ArgumentOutOfRangeException("length", "Must be greater than zero.");
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packet = buffer;
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position = length;
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header = new DnsHeader(new ArraySegment<byte>(packet, 0, 12));
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}
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public byte [] Packet {
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get { return packet; }
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}
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public int Length {
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get { return position; }
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}
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public DnsHeader Header {
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get { return header; }
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}
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protected void WriteUInt16 (ushort v)
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{
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packet [position++] = (byte) ((v & 0x0ff00) >> 8);
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packet [position++] = (byte) (v & 0x0ff);
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}
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protected void WriteStringBytes (string str, int offset, int count)
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{
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for (int i = offset, c = 0; c < count; c++, i++)
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packet [position++] = (byte) str [i]; // Don't care about encoding.
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}
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protected void WriteLabel (string str, int offset, int count)
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{
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packet [position++] = (byte) count;
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WriteStringBytes (str, offset, count);
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}
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protected void WriteDnsName (string name)
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{
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if (!DnsUtil.IsValidDnsName (name))
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throw new ArgumentException ("Invalid DNS name");
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if (!String.IsNullOrEmpty (name)) {
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int len = name.Length;
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int label_start = 0;
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int label_len = 0;
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for (int i = 0; i < len; i++) {
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char c = name [i];
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if (c != '.') {
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label_len++;
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} else {
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if (i == 0)
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break; // "."
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WriteLabel (name, label_start, label_len);
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label_start += label_len + 1; // Skip the dot
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label_len = 0;
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}
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}
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if (label_len > 0)
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WriteLabel (name, label_start, label_len);
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}
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packet [position++] = 0;
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}
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protected internal string ReadName (ref int offset)
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{
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return DnsUtil.ReadName (packet, ref offset);
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}
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protected internal static string ReadName (byte [] buffer, ref int offset)
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{
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return DnsUtil.ReadName (buffer, ref offset);
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}
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protected internal ushort ReadUInt16 (ref int offset)
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{
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return (ushort)((packet[offset++] << 8) + packet[offset++]);
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}
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protected internal int ReadInt32 (ref int offset)
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{
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return (packet [offset++] << 24) + (packet [offset++] << 16) + (packet [offset++] << 8) + packet [offset++];
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}
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}
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}
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