nebula/header.go

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2019-11-19 18:00:20 +01:00
package nebula
import (
"encoding/binary"
"encoding/json"
"errors"
"fmt"
)
//Version 1 header:
// 0 31
// |-----------------------------------------------------------------------|
// | Version (uint4) | Type (uint4) | Subtype (uint8) | Reserved (uint16) | 32
// |-----------------------------------------------------------------------|
// | Remote index (uint32) | 64
// |-----------------------------------------------------------------------|
// | Message counter | 96
// | (uint64) | 128
// |-----------------------------------------------------------------------|
// | payload... |
const (
Version uint8 = 1
HeaderLen = 16
)
type NebulaMessageType uint8
type NebulaMessageSubType uint8
const (
handshake NebulaMessageType = 0
message NebulaMessageType = 1
recvError NebulaMessageType = 2
lightHouse NebulaMessageType = 3
test NebulaMessageType = 4
closeTunnel NebulaMessageType = 5
//TODO These are deprecated as of 06/12/2018 - NB
testRemote NebulaMessageType = 6
testRemoteReply NebulaMessageType = 7
)
var typeMap = map[NebulaMessageType]string{
handshake: "handshake",
message: "message",
recvError: "recvError",
lightHouse: "lightHouse",
test: "test",
closeTunnel: "closeTunnel",
//TODO These are deprecated as of 06/12/2018 - NB
testRemote: "testRemote",
testRemoteReply: "testRemoteReply",
}
const (
testRequest NebulaMessageSubType = 0
testReply NebulaMessageSubType = 1
)
var eHeaderTooShort = errors.New("header is too short")
var subTypeTestMap = map[NebulaMessageSubType]string{
testRequest: "testRequest",
testReply: "testReply",
}
var subTypeNoneMap = map[NebulaMessageSubType]string{0: "none"}
var subTypeMap = map[NebulaMessageType]*map[NebulaMessageSubType]string{
message: &subTypeNoneMap,
recvError: &subTypeNoneMap,
lightHouse: &subTypeNoneMap,
test: &subTypeTestMap,
closeTunnel: &subTypeNoneMap,
handshake: {
handshakeIXPSK0: "ix_psk0",
},
//TODO: these are deprecated
testRemote: &subTypeNoneMap,
testRemoteReply: &subTypeNoneMap,
}
type Header struct {
Version uint8
Type NebulaMessageType
Subtype NebulaMessageSubType
Reserved uint16
RemoteIndex uint32
MessageCounter uint64
}
// HeaderEncode uses the provided byte array to encode the provided header values into.
// Byte array must be capped higher than HeaderLen or this will panic
func HeaderEncode(b []byte, v uint8, t uint8, st uint8, ri uint32, c uint64) []byte {
b = b[:HeaderLen]
b[0] = byte(v<<4 | (t & 0x0f))
b[1] = byte(st)
binary.BigEndian.PutUint16(b[2:4], 0)
binary.BigEndian.PutUint32(b[4:8], ri)
binary.BigEndian.PutUint64(b[8:16], c)
return b
}
// String creates a readable string representation of a header
func (h *Header) String() string {
if h == nil {
return "<nil>"
}
return fmt.Sprintf("ver=%d type=%s subtype=%s reserved=%#x remoteindex=%v messagecounter=%v",
h.Version, h.TypeName(), h.SubTypeName(), h.Reserved, h.RemoteIndex, h.MessageCounter)
}
// MarshalJSON creates a json string representation of a header
func (h *Header) MarshalJSON() ([]byte, error) {
return json.Marshal(m{
"version": h.Version,
"type": h.TypeName(),
"subType": h.SubTypeName(),
"reserved": h.Reserved,
"remoteIndex": h.RemoteIndex,
"messageCounter": h.MessageCounter,
})
}
// Encode turns header into bytes
func (h *Header) Encode(b []byte) ([]byte, error) {
if h == nil {
return nil, errors.New("nil header")
}
return HeaderEncode(b, h.Version, uint8(h.Type), uint8(h.Subtype), h.RemoteIndex, h.MessageCounter), nil
}
// Parse is a helper function to parses given bytes into new Header struct
func (h *Header) Parse(b []byte) error {
if len(b) < HeaderLen {
return eHeaderTooShort
}
// get upper 4 bytes
h.Version = uint8((b[0] >> 4) & 0x0f)
// get lower 4 bytes
h.Type = NebulaMessageType(b[0] & 0x0f)
h.Subtype = NebulaMessageSubType(b[1])
h.Reserved = binary.BigEndian.Uint16(b[2:4])
h.RemoteIndex = binary.BigEndian.Uint32(b[4:8])
h.MessageCounter = binary.BigEndian.Uint64(b[8:16])
return nil
}
// TypeName will transform the headers message type into a human string
func (h *Header) TypeName() string {
return TypeName(h.Type)
}
// TypeName will transform a nebula message type into a human string
func TypeName(t NebulaMessageType) string {
if n, ok := typeMap[t]; ok {
return n
}
return "unknown"
}
// SubTypeName will transform the headers message sub type into a human string
func (h *Header) SubTypeName() string {
return SubTypeName(h.Type, h.Subtype)
}
// SubTypeName will transform a nebula message sub type into a human string
func SubTypeName(t NebulaMessageType, s NebulaMessageSubType) string {
if n, ok := subTypeMap[t]; ok {
if x, ok := (*n)[s]; ok {
return x
}
}
return "unknown"
}
// NewHeader turns bytes into a header
func NewHeader(b []byte) (*Header, error) {
h := new(Header)
if err := h.Parse(b); err != nil {
return nil, err
}
return h, nil
}