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package packets
import (
"encoding/binary"
"fmt"
)
type Dot11CipherType uint8
const (
Dot11CipherWep Dot11CipherType = 1
Dot11CipherTkip Dot11CipherType = 2
Dot11CipherWrap Dot11CipherType = 3
Dot11CipherCcmp Dot11CipherType = 4
Dot11CipherWep104 Dot11CipherType = 5
)
func (a Dot11CipherType) String() string {
switch a {
case Dot11CipherWep:
return "WEP"
case Dot11CipherTkip:
return "TKIP"
case Dot11CipherWrap:
return "WRAP"
case Dot11CipherCcmp:
return "CCMP"
case Dot11CipherWep104:
return "WEP104"
default:
return "UNK"
}
}
type Dot11AuthType uint8
const (
Dot11AuthMgt Dot11AuthType = 1
Dot11AuthPsk Dot11AuthType = 2
)
func (a Dot11AuthType) String() string {
switch a {
case Dot11AuthMgt:
return "MGT"
case Dot11AuthPsk:
return "PSK"
default:
return "UNK"
}
}
type CipherSuite struct {
OUI []byte // 3 bytes
Type Dot11CipherType
}
type AuthSuite struct {
OUI []byte // 3 bytes
Type Dot11AuthType
}
type CipherSuiteSelector struct {
Count uint16
Suites []CipherSuite
}
type AuthSuiteSelector struct {
Count uint16
Suites []AuthSuite
}
type RSNInfo struct {
Version uint16
Group CipherSuite
Pairwise CipherSuiteSelector
AuthKey AuthSuiteSelector
}
type VendorInfo struct {
WPAVersion uint16
Multicast CipherSuite
Unicast CipherSuiteSelector
AuthKey AuthSuiteSelector
}
func canParse(what string, buf []byte, need int) error {
available := len(buf)
if need > available {
return fmt.Errorf("Malformed 802.11 packet, could not parse %s: needed %d bytes but only %d are available.", what, need, available)
}
return nil
}
func parsePairwiseSuite(buf []byte) (suite CipherSuite, err error) {
if err = canParse("RSN.Pairwise.Suite", buf, 4); err == nil {
suite.OUI = buf[0:3]
suite.Type = Dot11CipherType(buf[3])
}
return
}
func parseAuthkeySuite(buf []byte) (suite AuthSuite, err error) {
if err = canParse("RSN.AuthKey.Suite", buf, 4); err == nil {
suite.OUI = buf[0:3]
suite.Type = Dot11AuthType(buf[3])
}
return
}
func Dot11InformationElementVendorInfoDecode(buf []byte) (v VendorInfo, err error) {
if err = canParse("Vendor", buf, 8); err == nil {
v.WPAVersion = binary.LittleEndian.Uint16(buf[0:2])
v.Multicast.OUI = buf[2:5]
v.Multicast.Type = Dot11CipherType(buf[5])
v.Unicast.Count = binary.LittleEndian.Uint16(buf[6:8])
buf = buf[8:]
} else {
v.Unicast.Count = 0
return
}
// check what we're left with
if err = canParse("Vendor.Unicast.Suites", buf, int(v.Unicast.Count)*4); err == nil {
for i := uint16(0); i < v.Unicast.Count; i++ {
if suite, err := parsePairwiseSuite(buf); err == nil {
v.Unicast.Suites = append(v.Unicast.Suites, suite)
buf = buf[4:]
} else {
return v, err
}
}
} else {
v.Unicast.Count = 0
return
}
if err = canParse("Vendor.AuthKey.Count", buf, 2); err == nil {
v.AuthKey.Count = binary.LittleEndian.Uint16(buf[0:2])
buf = buf[2:]
} else {
v.AuthKey.Count = 0
return
}
// just like before, check if we have enough data
if err = canParse("Vendor.AuthKey.Suites", buf, int(v.AuthKey.Count)*4); err == nil {
for i := uint16(0); i < v.AuthKey.Count; i++ {
if suite, err := parseAuthkeySuite(buf); err == nil {
v.AuthKey.Suites = append(v.AuthKey.Suites, suite)
buf = buf[4:]
} else {
return v, err
}
}
} else {
v.AuthKey.Count = 0
}
return
}
func Dot11InformationElementRSNInfoDecode(buf []byte) (rsn RSNInfo, err error) {
if err = canParse("RSN", buf, 8); err == nil {
rsn.Version = binary.LittleEndian.Uint16(buf[0:2])
rsn.Group.OUI = buf[2:5]
rsn.Group.Type = Dot11CipherType(buf[5])
rsn.Pairwise.Count = binary.LittleEndian.Uint16(buf[6:8])
buf = buf[8:]
} else {
rsn.Pairwise.Count = 0
return
}
// check what we're left with
if err = canParse("RSN.Pairwise.Suites", buf, int(rsn.Pairwise.Count)*4); err == nil {
for i := uint16(0); i < rsn.Pairwise.Count; i++ {
if suite, err := parsePairwiseSuite(buf); err == nil {
rsn.Pairwise.Suites = append(rsn.Pairwise.Suites, suite)
buf = buf[4:]
} else {
return rsn, err
}
}
} else {
rsn.Pairwise.Count = 0
return
}
if err = canParse("RSN.AuthKey.Count", buf, 2); err == nil {
rsn.AuthKey.Count = binary.LittleEndian.Uint16(buf[0:2])
buf = buf[2:]
} else {
rsn.AuthKey.Count = 0
return
}
// just like before, check if we have enough data
if err = canParse("RSN.AuthKey.Suites", buf, int(rsn.AuthKey.Count)*4); err == nil {
for i := uint16(0); i < rsn.AuthKey.Count; i++ {
if suite, err := parseAuthkeySuite(buf); err == nil {
rsn.AuthKey.Suites = append(rsn.AuthKey.Suites, suite)
buf = buf[4:]
} else {
return rsn, err
}
}
} else {
rsn.AuthKey.Count = 0
}
return
}
func Dot11InformationElementIDDSSetDecode(buf []byte) (channel int, err error) {
if err = canParse("DSSet.channel", buf, 1); err == nil {
channel = int(buf[0])
}
return
}
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