107 lines
4.0 KiB
C#
107 lines
4.0 KiB
C#
/*
|
|
This file is part of PacketDotNet
|
|
|
|
PacketDotNet is free software: you can redistribute it and/or modify
|
|
it under the terms of the GNU Lesser General Public License as published by
|
|
the Free Software Foundation, either version 3 of the License, or
|
|
(at your option) any later version.
|
|
|
|
PacketDotNet is distributed in the hope that it will be useful,
|
|
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
GNU Lesser General Public License for more details.
|
|
|
|
You should have received a copy of the GNU Lesser General Public License
|
|
along with PacketDotNet. If not, see <http://www.gnu.org/licenses/>.
|
|
*/
|
|
/*
|
|
* Copyright 2012 Alan Rushforth <alan.rushforth@gmail.com>
|
|
*/
|
|
|
|
using System;
|
|
using System.Collections.Generic;
|
|
using System.Linq;
|
|
using System.Text;
|
|
using PacketDotNet.Utils;
|
|
|
|
namespace PacketDotNet
|
|
{
|
|
namespace Ieee80211
|
|
{
|
|
/// <summary>
|
|
/// Null data frames are like normal data frames except they carry no payload. They are primarily used for control purposes
|
|
/// such as power management or telling an Access Point to buffer packets while a station scans other channels.
|
|
/// </summary>
|
|
public class NullDataFrame : DataFrame
|
|
{
|
|
/// <summary>
|
|
/// Length of the frame header.
|
|
///
|
|
/// This does not include the FCS, it represents only the header bytes that would
|
|
/// would preceed any payload.
|
|
/// </summary>
|
|
public override int FrameSize
|
|
{
|
|
get
|
|
{
|
|
//if we are in WDS mode then there are 4 addresses (normally it is just 3)
|
|
int numOfAddressFields = (FrameControl.ToDS && FrameControl.FromDS) ? 4 : 3;
|
|
|
|
return (MacFields.FrameControlLength +
|
|
MacFields.DurationIDLength +
|
|
(MacFields.AddressLength * numOfAddressFields) +
|
|
MacFields.SequenceControlLength);
|
|
}
|
|
}
|
|
|
|
/// <summary>
|
|
/// Initializes a new instance of the <see cref="PacketDotNet.Ieee80211.NullDataFrame"/> class.
|
|
/// </summary>
|
|
/// <param name='bas'>
|
|
/// A <see cref="ByteArraySegment"/>
|
|
/// </param>
|
|
public NullDataFrame (ByteArraySegment bas)
|
|
{
|
|
header = new ByteArraySegment (bas);
|
|
|
|
FrameControl = new FrameControlField (FrameControlBytes);
|
|
Duration = new DurationField (DurationBytes);
|
|
SequenceControl = new SequenceControlField (SequenceControlBytes);
|
|
ReadAddresses ();
|
|
|
|
header.Length = FrameSize;
|
|
}
|
|
|
|
/// <summary>
|
|
/// Initializes a new instance of the <see cref="PacketDotNet.Ieee80211.NullDataFrame"/> class.
|
|
/// </summary>
|
|
public NullDataFrame ()
|
|
{
|
|
this.FrameControl = new FrameControlField ();
|
|
this.Duration = new DurationField ();
|
|
this.SequenceControl = new SequenceControlField ();
|
|
AssignDefaultAddresses ();
|
|
|
|
FrameControl.SubType = FrameControlField.FrameSubTypes.DataNullFunctionNoData;
|
|
}
|
|
|
|
/// <summary>
|
|
/// Writes the current packet properties to the backing ByteArraySegment.
|
|
/// </summary>
|
|
public override void UpdateCalculatedValues ()
|
|
{
|
|
if ((header == null) || (header.Length > (header.BytesLength - header.Offset)) || (header.Length < FrameSize))
|
|
{
|
|
header = new ByteArraySegment (new Byte[FrameSize]);
|
|
}
|
|
|
|
this.FrameControlBytes = this.FrameControl.Field;
|
|
this.DurationBytes = this.Duration.Field;
|
|
this.SequenceControlBytes = this.SequenceControl.Field;
|
|
WriteAddressBytes ();
|
|
}
|
|
|
|
}
|
|
}
|
|
}
|