346 lines
12 KiB
C#
346 lines
12 KiB
C#
/*
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This file is part of PacketDotNet
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PacketDotNet is free software: you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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PacketDotNet is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with PacketDotNet. If not, see <http://www.gnu.org/licenses/>.
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*/
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/*
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* Copyright 2009 Chris Morgan <chmorgan@gmail.com>
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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 PacketDotNet.Utils;
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using MiscUtil.Conversion;
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namespace PacketDotNet
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{
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/// <summary>
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/// User datagram protocol
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/// See http://en.wikipedia.org/wiki/Udp
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/// </summary>
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public class UdpPacket : TransportPacket
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{
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// NOTE: No need to warn about lack of use, the compiler won't
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// put any calls to 'log' here but we need 'log' to exist to compile
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#pragma warning disable 0169, 0649
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private static readonly ILogInactive log;
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#pragma warning restore 0169, 0649
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/// <summary> Fetch the port number on the source host.</summary>
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virtual public ushort SourcePort
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{
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get
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{
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return EndianBitConverter.Big.ToUInt16(header.Bytes, header.Offset + UdpFields.SourcePortPosition);
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}
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set
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{
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var val = value;
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EndianBitConverter.Big.CopyBytes(val, header.Bytes, header.Offset + UdpFields.SourcePortPosition);
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}
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}
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/// <summary> Fetch the port number on the target host.</summary>
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virtual public ushort DestinationPort
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{
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get
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{
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return EndianBitConverter.Big.ToUInt16(header.Bytes,
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header.Offset + UdpFields.DestinationPortPosition);
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}
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set
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{
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var val = value;
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EndianBitConverter.Big.CopyBytes(val,
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header.Bytes,
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header.Offset + UdpFields.DestinationPortPosition);
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}
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}
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/// <value>
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/// Length in bytes of the header and payload, minimum size of 8,
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/// the size of the Udp header
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/// </value>
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virtual public int Length
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{
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get
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{
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return EndianBitConverter.Big.ToInt16(header.Bytes,
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header.Offset + UdpFields.HeaderLengthPosition);
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}
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// Internal because it is updated based on the payload when
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// its bytes are retrieved
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internal set
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{
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var val = (Int16)value;
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EndianBitConverter.Big.CopyBytes(val,
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header.Bytes,
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header.Offset + UdpFields.HeaderLengthPosition);
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}
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}
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/// <summary> Fetch the header checksum.</summary>
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override public ushort Checksum
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{
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get
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{
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return EndianBitConverter.Big.ToUInt16(header.Bytes,
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header.Offset + UdpFields.ChecksumPosition);
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}
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set
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{
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var val = value;
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EndianBitConverter.Big.CopyBytes(val,
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header.Bytes,
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header.Offset + UdpFields.ChecksumPosition);
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}
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}
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/// <summary> Check if the UDP packet is valid, checksum-wise.</summary>
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public bool ValidChecksum
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{
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get
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{
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// IPv6 has no checksum so only the TCP checksum needs evaluation
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if (ParentPacket.GetType() == typeof(IPv6Packet))
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return ValidUDPChecksum;
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// For IPv4 both the IP layer and the TCP layer contain checksums
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else
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return ((IPv4Packet)ParentPacket).ValidIPChecksum && ValidUDPChecksum;
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}
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}
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/// <value>
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/// True if the udp checksum is valid
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/// </value>
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virtual public bool ValidUDPChecksum
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{
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get
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{
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log.Debug("ValidUDPChecksum");
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var retval = IsValidChecksum(TransportPacket.TransportChecksumOption.AttachPseudoIPHeader);
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log.DebugFormat("ValidUDPChecksum {0}", retval);
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return retval;
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}
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}
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/// <summary> Fetch ascii escape sequence of the color associated with this packet type.</summary>
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override public System.String Color
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{
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get
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{
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return AnsiEscapeSequences.LightGreen;
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}
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}
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/// <summary>
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/// Update the Udp length
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/// </summary>
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public override void UpdateCalculatedValues ()
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{
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// update the length field based on the length of this packet header
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// plus the length of all of the packets it contains
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Length = TotalPacketLength;
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UpdateUDPChecksum();
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}
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/// <summary>
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/// Create from values
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/// </summary>
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/// <param name="SourcePort">
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/// A <see cref="System.UInt16"/>
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/// </param>
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/// <param name="DestinationPort">
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/// A <see cref="System.UInt16"/>
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/// </param>
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public UdpPacket(ushort SourcePort, ushort DestinationPort)
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{
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log.Debug("");
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// allocate memory for this packet
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int offset = 0;
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int length = UdpFields.HeaderLength;
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var headerBytes = new byte[length];
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header = new ByteArraySegment(headerBytes, offset, length);
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// set instance values
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this.SourcePort = SourcePort;
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this.DestinationPort = DestinationPort;
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}
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/// <summary>
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/// Constructor
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/// </summary>
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/// <param name="bas">
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/// A <see cref="ByteArraySegment"/>
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/// </param>
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public UdpPacket(ByteArraySegment bas)
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{
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log.DebugFormat("bas {0}", bas.ToString());
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// set the header field, header field values are retrieved from this byte array
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header = new ByteArraySegment(bas);
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RandomUtils.EnsurePacketLength(this, UdpFields.HeaderLength, header.Length);
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header.Length = UdpFields.HeaderLength;
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payloadPacketOrData = new PacketOrByteArraySegment();
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// is this packet going to port 7 or 9? if so it might be a WakeOnLan packet
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const int wakeOnLanPort0 = 7;
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const int wakeOnLanPort1 = 9;
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if(DestinationPort.Equals(wakeOnLanPort0) || DestinationPort.Equals (wakeOnLanPort1))
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{
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payloadPacketOrData.ThePacket = new WakeOnLanPacket(header.EncapsulatedBytes());
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} else
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{
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// store the payload bytes
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payloadPacketOrData.TheByteArraySegment = header.EncapsulatedBytes();
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}
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}
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/// <summary>
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/// Constructor
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/// </summary>
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/// <param name="bas">
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/// A <see cref="ByteArraySegment"/>
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/// </param>
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/// <param name="ParentPacket">
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/// A <see cref="Packet"/>
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/// </param>
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public UdpPacket(ByteArraySegment bas,
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Packet ParentPacket) :
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this(bas)
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{
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this.ParentPacket = ParentPacket;
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}
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/// <summary>
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/// Calculates the UDP checksum, optionally updating the UDP checksum header.
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/// </summary>
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/// <returns>The calculated UDP checksum.</returns>
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public int CalculateUDPChecksum()
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{
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var newChecksum = CalculateChecksum(TransportChecksumOption.AttachPseudoIPHeader);
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return newChecksum;
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}
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/// <summary>
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/// Update the checksum value.
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/// </summary>
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public void UpdateUDPChecksum()
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{
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this.Checksum = (ushort)CalculateUDPChecksum();
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}
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/// <summary cref="Packet.ToString(StringOutputType)" />
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public override string ToString(StringOutputType outputFormat)
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{
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var buffer = new StringBuilder();
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string color = "";
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string colorEscape = "";
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if(outputFormat == StringOutputType.Colored || outputFormat == StringOutputType.VerboseColored)
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{
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color = Color;
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colorEscape = AnsiEscapeSequences.Reset;
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}
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if(outputFormat == StringOutputType.Normal || outputFormat == StringOutputType.Colored)
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{
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buffer.AppendFormat("{0}[UDPPacket: SourcePort={2}, DestinationPort={3}]{1}",
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color,
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colorEscape,
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SourcePort,
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DestinationPort);
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}
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if(outputFormat == StringOutputType.Verbose || outputFormat == StringOutputType.VerboseColored)
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{
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// collect the properties and their value
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Dictionary<string,string> properties = new Dictionary<string,string>();
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properties.Add("source", SourcePort.ToString());
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properties.Add("destination", DestinationPort.ToString());
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properties.Add("length", Length.ToString());
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properties.Add("checksum", "0x" + Checksum.ToString("x") + " [" + (ValidUDPChecksum ? "valid" : "invalid") + "]");
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// calculate the padding needed to right-justify the property names
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int padLength = Utils.RandomUtils.LongestStringLength(new List<string>(properties.Keys));
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// build the output string
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buffer.AppendLine("UDP: ******* UDP - \"User Datagram Protocol\" - offset=? length=" + TotalPacketLength);
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buffer.AppendLine("UDP:");
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foreach(var property in properties)
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{
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buffer.AppendLine("UDP: " + property.Key.PadLeft(padLength) + " = " + property.Value);
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}
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buffer.AppendLine("UDP:");
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}
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// append the base string output
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buffer.Append(base.ToString(outputFormat));
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return buffer.ToString();
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}
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/// <summary>
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/// Returns the UdpPacket inside of the Packet p or null if
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/// there is no encapsulated packet
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/// </summary>
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/// <param name="p">
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/// A <see cref="Packet"/>
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/// </param>
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/// <returns>
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/// A <see cref="UdpPacket"/>
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/// </returns>
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[Obsolete("Use Packet.Extract() instead")]
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public static UdpPacket GetEncapsulated(Packet p)
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{
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if(p is InternetLinkLayerPacket)
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{
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var payload = InternetLinkLayerPacket.GetInnerPayload((InternetLinkLayerPacket)p);
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if(payload is IpPacket)
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{
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var innerPayload = payload.PayloadPacket;
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if(innerPayload is UdpPacket)
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{
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return (UdpPacket)innerPayload;
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}
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}
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}
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return null;
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}
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/// <summary>
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/// Generate a random packet
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/// </summary>
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/// <returns>
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/// A <see cref="UdpPacket"/>
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/// </returns>
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public static UdpPacket RandomPacket()
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{
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var rnd = new Random();
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var SourcePort = (ushort)rnd.Next(ushort.MinValue, ushort.MaxValue);
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var DestinationPort = (ushort)rnd.Next(ushort.MinValue, ushort.MaxValue);
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return new UdpPacket(SourcePort, DestinationPort);
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}
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}
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}
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