147 lines
4.6 KiB
Go
147 lines
4.6 KiB
Go
// Copyright 2015 Google, Inc. All rights reserved.
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//
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// Use of this source code is governed by a BSD-style license
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// that can be found in the LICENSE file in the root of the source
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// tree.
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// http://www.tcpdump.org/linktypes/LINKTYPE_IEEE802_11_PRISM.html
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package layers
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import (
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"encoding/binary"
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"errors"
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"github.com/google/gopacket"
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)
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func decodePrismValue(data []byte, pv *PrismValue) {
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pv.DID = PrismDID(binary.LittleEndian.Uint32(data[0:4]))
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pv.Status = binary.LittleEndian.Uint16(data[4:6])
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pv.Length = binary.LittleEndian.Uint16(data[6:8])
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pv.Data = data[8 : 8+pv.Length]
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}
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type PrismDID uint32
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const (
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PrismDIDType1HostTime PrismDID = 0x10044
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PrismDIDType2HostTime PrismDID = 0x01041
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PrismDIDType1MACTime PrismDID = 0x20044
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PrismDIDType2MACTime PrismDID = 0x02041
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PrismDIDType1Channel PrismDID = 0x30044
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PrismDIDType2Channel PrismDID = 0x03041
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PrismDIDType1RSSI PrismDID = 0x40044
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PrismDIDType2RSSI PrismDID = 0x04041
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PrismDIDType1SignalQuality PrismDID = 0x50044
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PrismDIDType2SignalQuality PrismDID = 0x05041
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PrismDIDType1Signal PrismDID = 0x60044
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PrismDIDType2Signal PrismDID = 0x06041
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PrismDIDType1Noise PrismDID = 0x70044
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PrismDIDType2Noise PrismDID = 0x07041
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PrismDIDType1Rate PrismDID = 0x80044
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PrismDIDType2Rate PrismDID = 0x08041
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PrismDIDType1TransmittedFrameIndicator PrismDID = 0x90044
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PrismDIDType2TransmittedFrameIndicator PrismDID = 0x09041
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PrismDIDType1FrameLength PrismDID = 0xA0044
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PrismDIDType2FrameLength PrismDID = 0x0A041
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)
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const (
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PrismType1MessageCode uint16 = 0x00000044
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PrismType2MessageCode uint16 = 0x00000041
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)
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func (p PrismDID) String() string {
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dids := map[PrismDID]string{
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PrismDIDType1HostTime: "Host Time",
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PrismDIDType2HostTime: "Host Time",
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PrismDIDType1MACTime: "MAC Time",
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PrismDIDType2MACTime: "MAC Time",
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PrismDIDType1Channel: "Channel",
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PrismDIDType2Channel: "Channel",
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PrismDIDType1RSSI: "RSSI",
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PrismDIDType2RSSI: "RSSI",
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PrismDIDType1SignalQuality: "Signal Quality",
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PrismDIDType2SignalQuality: "Signal Quality",
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PrismDIDType1Signal: "Signal",
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PrismDIDType2Signal: "Signal",
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PrismDIDType1Noise: "Noise",
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PrismDIDType2Noise: "Noise",
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PrismDIDType1Rate: "Rate",
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PrismDIDType2Rate: "Rate",
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PrismDIDType1TransmittedFrameIndicator: "Transmitted Frame Indicator",
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PrismDIDType2TransmittedFrameIndicator: "Transmitted Frame Indicator",
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PrismDIDType1FrameLength: "Frame Length",
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PrismDIDType2FrameLength: "Frame Length",
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}
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if str, ok := dids[p]; ok {
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return str
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}
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return "Unknown DID"
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}
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type PrismValue struct {
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DID PrismDID
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Status uint16
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Length uint16
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Data []byte
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}
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func (pv *PrismValue) IsSupplied() bool {
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return pv.Status == 1
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}
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var ErrPrismExpectedMoreData = errors.New("Expected more data.")
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var ErrPrismInvalidCode = errors.New("Invalid header code.")
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func decodePrismHeader(data []byte, p gopacket.PacketBuilder) error {
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d := &PrismHeader{}
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return decodingLayerDecoder(d, data, p)
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}
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type PrismHeader struct {
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BaseLayer
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Code uint16
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Length uint16
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DeviceName string
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Values []PrismValue
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}
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func (m *PrismHeader) LayerType() gopacket.LayerType { return LayerTypePrismHeader }
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func (m *PrismHeader) DecodeFromBytes(data []byte, df gopacket.DecodeFeedback) error {
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m.Code = binary.LittleEndian.Uint16(data[0:4])
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m.Length = binary.LittleEndian.Uint16(data[4:8])
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m.DeviceName = string(data[8:24])
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m.BaseLayer = BaseLayer{Contents: data[:m.Length], Payload: data[m.Length:len(data)]}
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switch m.Code {
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case PrismType1MessageCode:
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fallthrough
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case PrismType2MessageCode:
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// valid message code
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default:
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return ErrPrismInvalidCode
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}
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offset := uint16(24)
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m.Values = make([]PrismValue, (m.Length-offset)/12)
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for i := 0; i < len(m.Values); i++ {
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decodePrismValue(data[offset:offset+12], &m.Values[i])
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offset += 12
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}
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if offset != m.Length {
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return ErrPrismExpectedMoreData
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}
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return nil
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}
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func (m *PrismHeader) CanDecode() gopacket.LayerClass { return LayerTypePrismHeader }
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func (m *PrismHeader) NextLayerType() gopacket.LayerType { return LayerTypeDot11 }
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