/
frame.go
executable file
·232 lines (212 loc) · 6.56 KB
/
frame.go
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// +build linux
package gopenflow
import (
"encoding/binary"
"fmt"
"github.com/google/gopacket"
"github.com/google/gopacket/layers"
"github.com/hkwi/gopenflow/oxm"
"github.com/hkwi/nlgo"
layers2 "github.com/hkwi/suppl/gopacket/layers"
)
type frameError string
func (self frameError) Error() string {
return string(self)
}
func makeLwapp(dot11pkt, mac []byte, fragmentId uint8) ([]byte, error) {
//
// Ether HDR + LWAPP HDR + 802.11(without FCS)
//
// as wireshark lwapp dissector handles.
//
pkt := make([]byte, 20, 20+len(dot11pkt))
// eth dst is any
copy(pkt[6:12], mac) // eth src is mac
binary.BigEndian.PutUint16(pkt[12:14], 0x88bb) // LWAPP(L2)
// LWAPP header
pkt[15] = fragmentId // LWAPP Frag ID
binary.BigEndian.PutUint16(pkt[16:18], uint16(len(dot11pkt))) // LWAPP Length
// Status/WLANs is zero
return append(pkt, dot11pkt...), nil
}
type oxmExperimenter struct {
Experimenter uint32
Field uint8
Value []byte
}
func (self oxmExperimenter) Bytes() []byte {
buf := make([]byte, 8+len(self.Value))
hdr := uint32(0xffff0000)
hdr |= uint32(self.Field) << 9
hdr |= uint32(4 + len(self.Value))
binary.BigEndian.PutUint32(buf, hdr)
binary.BigEndian.PutUint32(buf[4:], self.Experimenter)
copy(buf[8:], self.Value)
return buf
}
func fetchOxmExperimenter(buf []byte) []oxmExperimenter {
var ret []oxmExperimenter
for len(buf) > 10 {
hdr := binary.BigEndian.Uint32(buf)
length := int(hdr & 0x7F)
if (hdr >> 16) == 0xffff {
ret = append(ret, oxmExperimenter{
Experimenter: binary.BigEndian.Uint32(buf[4:]),
Field: uint8(hdr >> 9),
Value: buf[8 : 4+length],
})
}
buf = buf[4+length:]
}
return ret
}
func FrameFromRadiotap(rt *layers.RadioTap, mac []byte, fragmentId uint8) (Frame, error) {
var status [2]uint8
dot11 := layers2.FetchDot11FromRadioTap(rt)
if dot11 == nil {
return Frame{}, frameError("frame error")
}
oob := oxmExperimenter{
Experimenter: oxm.STRATOS_EXPERIMENTER_ID,
Field: oxm.STROXM_BASIC_DOT11,
Value: []byte{1},
}.Bytes()
radiotapAdd := func(expType uint8, value []byte) {
oob = append(oob, oxmExperimenter{
Experimenter: oxm.STRATOS_EXPERIMENTER_ID,
Field: expType,
Value: value,
}.Bytes()...)
}
if rt.Present.TSFT() {
buf := make([]byte, 8)
binary.LittleEndian.PutUint64(buf, rt.TSFT)
radiotapAdd(oxm.STROXM_RADIOTAP_TSFT, buf)
}
if rt.Present.Flags() {
radiotapAdd(oxm.STROXM_RADIOTAP_FLAGS, []byte{uint8(rt.Flags)})
}
if rt.Present.Rate() {
radiotapAdd(oxm.STROXM_RADIOTAP_RATE, []byte{uint8(rt.Rate)})
}
if rt.Present.Channel() {
buf := make([]byte, 4)
binary.LittleEndian.PutUint16(buf, uint16(rt.ChannelFrequency))
binary.LittleEndian.PutUint16(buf[2:], uint16(rt.ChannelFlags))
radiotapAdd(oxm.STROXM_RADIOTAP_CHANNEL, buf)
}
if rt.Present.FHSS() {
buf := make([]byte, 2)
binary.LittleEndian.PutUint16(buf, rt.FHSS)
radiotapAdd(oxm.STROXM_RADIOTAP_FHSS, buf)
}
if rt.Present.DBMAntennaSignal() {
status[0] = uint8(rt.DBMAntennaSignal) // RSSI in dBm
radiotapAdd(oxm.STROXM_RADIOTAP_DBM_ANTSIGNAL, []byte{uint8(rt.DBMAntennaSignal)})
}
if rt.Present.DBMAntennaNoise() {
if rt.Present.DBMAntennaSignal() {
status[1] = uint8(rt.DBMAntennaSignal - rt.DBMAntennaNoise) // SNR in dB
}
radiotapAdd(oxm.STROXM_RADIOTAP_DBM_ANTNOISE, []byte{uint8(rt.DBMAntennaNoise)})
}
if rt.Present.LockQuality() {
buf := make([]byte, 2)
binary.LittleEndian.PutUint16(buf, rt.LockQuality)
radiotapAdd(oxm.STROXM_RADIOTAP_LOCK_QUALITY, buf)
}
if rt.Present.TxAttenuation() {
buf := make([]byte, 2)
binary.LittleEndian.PutUint16(buf, rt.TxAttenuation)
radiotapAdd(oxm.STROXM_RADIOTAP_TX_ATTENUATION, buf)
}
if rt.Present.DBTxAttenuation() {
buf := make([]byte, 8)
binary.LittleEndian.PutUint16(buf, rt.DBTxAttenuation)
radiotapAdd(oxm.STROXM_RADIOTAP_DB_TX_ATTENUATION, buf)
}
if rt.Present.DBMTxPower() {
radiotapAdd(oxm.STROXM_RADIOTAP_DBM_TX_POWER, []byte{uint8(rt.DBMTxPower)})
}
if rt.Present.Antenna() {
radiotapAdd(oxm.STROXM_RADIOTAP_ANTENNA, []byte{rt.Antenna})
}
if rt.Present.DBAntennaSignal() {
radiotapAdd(oxm.STROXM_RADIOTAP_DB_ANTSIGNAL, []byte{uint8(rt.DBAntennaSignal)})
}
if rt.Present.DBAntennaNoise() {
radiotapAdd(oxm.STROXM_RADIOTAP_DB_ANTNOISE, []byte{uint8(rt.DBAntennaNoise)})
}
if rt.Present.RxFlags() {
// gopacket no-impl
}
if rt.Present.TxFlags() {
// gopacket no-impl
}
if rt.Present.RtsRetries() {
// gopacket no-impl
}
if rt.Present.DataRetries() {
// gopacket no-impl
}
if data, err := makeLwapp(dot11, mac, fragmentId); err != nil {
return Frame{}, err
} else {
copy(data[18:], status[:])
return Frame{
Data: data,
Oob: oob,
}, nil
}
}
func (self *Frame) Dot11() ([]byte, error) {
// requires LWAPP gopacket registration here
dpkt := gopacket.NewPacket(self.Data, layers.LayerTypeEthernet, gopacket.Lazy)
if dot11Layer := dpkt.Layer(layers.LayerTypeDot11); dot11Layer != nil {
dot11, _ := dot11Layer.(*layers.Dot11)
payload := make([]byte, len(dot11.Contents)+len(dot11.Payload)+4)
copy(payload, dot11.Contents)
copy(payload[len(dot11.Contents):], dot11.Payload)
binary.LittleEndian.PutUint32(payload[len(dot11.Contents)+len(dot11.Payload):], dot11.Checksum)
return payload, nil
}
return nil, fmt.Errorf("no dot11 layer")
}
func (self *Frame) Radiotap() ([]byte, error) {
if dot11pkt, err := self.Dot11(); err != nil {
return nil, err
} else {
// dropping all of oob information here. by the way, kernel can handle
// RADIOTAP_FLAGS and RADIOTAP_TX_FLAGS
length := 8 + len(dot11pkt)
pkt := make([]byte, 8, length)
binary.LittleEndian.PutUint16(pkt[2:], uint16(length))
pkt = append(pkt, dot11pkt...)
return pkt, nil
}
}
func FrameFromNlAttr(attrs nlgo.AttrMap, mac []byte, fragmentId uint8) (Frame, error) {
freq := uint32(attrs.Get(nlgo.NL80211_ATTR_WIPHY_FREQ).(nlgo.U32))
freqValue := make([]byte, 3)
binary.LittleEndian.PutUint16(freqValue, uint16(freq))
oob := oxmExperimenter{
Experimenter: oxm.STRATOS_EXPERIMENTER_ID,
Field: oxm.STROXM_RADIOTAP_CHANNEL,
Value: freqValue,
}.Bytes()
if t := attrs.Get(nlgo.NL80211_ATTR_RX_SIGNAL_DBM); t != nil {
oob = append(oob, oxmExperimenter{
Experimenter: oxm.STRATOS_EXPERIMENTER_ID,
Field: oxm.STROXM_RADIOTAP_DBM_ANTSIGNAL,
Value: []byte{uint8(t.(nlgo.U32))},
}.Bytes()...)
}
if data, err := makeLwapp([]byte(attrs.Get(nlgo.NL80211_ATTR_FRAME).(nlgo.Binary)), mac, fragmentId); err != nil {
return Frame{}, err
} else {
return Frame{
Data: data,
Oob: oob,
}, nil
}
}