func (mod *module) handle_connect(ch *e3x.Channel) {
defer ch.Kill()
var (
from hashname.H
localIdent *e3x.Identity
remoteIdent *e3x.Identity
handshake cipherset.Handshake
innerData = bufpool.New()
err error
)
localIdent, err = mod.e.LocalIdentity()
if err != nil {
return
}
pkt, err := ch.ReadPacket()
if err != nil {
return
}
pkt.Body(innerData.SetLen(pkt.BodyLen()).RawBytes()[:0])
inner, err := lob.Decode(innerData)
if err != nil {
return
}
innerHdr := inner.Header()
if innerHdr.IsBinary() && len(innerHdr.Bytes) == 1 {
// handshake
var (
csid = innerHdr.Bytes[0]
key = localIdent.Keys()[csid]
)
if key == nil {
return
}
handshake, err = cipherset.DecryptHandshake(csid, key, inner.Body(nil))
if err != nil {
return
}
from, err = hashname.FromIntermediates(handshake.Parts())
if err != nil {
return
}
remoteIdent, err = e3x.NewIdentity(cipherset.Keys{
handshake.CSID(): handshake.PublicKey(),
}, handshake.Parts(), nil)
if err != nil {
return
}
} else {
// key packet
var parts = make(cipherset.Parts)
var csid uint8
for key, value := range inner.Header().Extra {
if len(key) != 2 {
continue
}
keyData, err := hex.DecodeString(key)
if err != nil {
continue
}
partCSID := keyData[0]
switch v := value.(type) {
case bool:
csid = partCSID
case string:
parts[partCSID] = v
}
}
hn, err := hashname.FromKeyAndIntermediates(csid, inner.Body(nil), parts)
if err != nil {
return
}
from = hn
pubKey, err := cipherset.DecodeKeyBytes(csid, inner.Body(nil), nil)
if err != nil {
return
}
remoteIdent, err = e3x.NewIdentity(cipherset.Keys{csid: pubKey}, parts, nil)
if err != nil {
return
}
}
if from == "" {
return
}
if mod.config.AllowConnect != nil && !mod.config.AllowConnect(from, ch.RemoteHashname()) {
return
}
x, err := mod.e.CreateExchange(remoteIdent)
if err != nil {
return
}
// when the BODY contains a handshake
if handshake != nil {
routerExchange := ch.Exchange()
routerAddr := &peerAddr{
router: routerExchange.RemoteHashname(),
}
conn := newConnection(x.RemoteHashname(), routerAddr, routerExchange, func() {
mod.unregisterConnection(routerExchange, x.LocalToken())
})
pipe, added := x.AddPipeConnection(conn, nil)
if added {
mod.registerConnection(routerExchange, x.LocalToken(), conn)
}
resp, ok := x.ApplyHandshake(handshake, pipe)
if !ok {
return
}
if resp != nil {
err = mod.peerVia(ch.Exchange(), from, resp)
if err != nil {
return
}
}
}
// when the BODY contains a key packet
if handshake == nil {
pkt, err := x.GenerateHandshake()
if err != nil {
return
}
err = mod.peerVia(ch.Exchange(), from, pkt)
if err != nil {
return
}
}
// Notify on-exchange callbacks
mod.getIntroduction(from).resolve(x, nil)
}
func (s *state) DecryptPacket(pkt *lob.Packet) (*lob.Packet, error) {
s.mtx.RLock()
defer s.mtx.RUnlock()
if !s.CanDecryptPacket() {
return nil, cipherset.ErrInvalidState
}
if pkt == nil {
return nil, nil
}
if !pkt.Header().IsZero() || pkt.BodyLen() < 16+4+4 {
return nil, cipherset.ErrInvalidPacket
}
var (
nonce [16]byte
bodyRaw []byte
innerRaw []byte
innerLen = pkt.BodyLen() - (16 + 4 + 4)
body = bufpool.New()
inner = bufpool.New().SetLen(innerLen)
)
pkt.Body(body.SetLen(pkt.BodyLen()).RawBytes()[:0])
bodyRaw = body.RawBytes()
innerRaw = inner.RawBytes()
// compare token
if !bytes.Equal(bodyRaw[:16], (*s.localToken)[:]) {
inner.Free()
body.Free()
return nil, cipherset.ErrInvalidPacket
}
// copy nonce
copy(nonce[:], bodyRaw[16:16+4])
{ // verify hmac
mac := bodyRaw[16+4+innerLen:]
macKey := append(s.lineDecryptionKey, nonce[:4]...)
h := hmac.New(sha256.New, macKey)
h.Write(bodyRaw[16+4 : 16+4+innerLen])
if subtle.ConstantTimeCompare(mac, fold(h.Sum(nil), 4)) != 1 {
inner.Free()
body.Free()
return nil, cipherset.ErrInvalidPacket
}
}
{ // decrypt inner
aesBlock, err := aes.NewCipher(s.lineDecryptionKey)
if err != nil {
inner.Free()
body.Free()
return nil, err
}
aes := Cipher.NewCTR(aesBlock, nonce[:])
if aes == nil {
inner.Free()
body.Free()
return nil, cipherset.ErrInvalidPacket
}
aes.XORKeyStream(innerRaw, bodyRaw[16+4:16+4+innerLen])
}
innerPkt, err := lob.Decode(inner)
if err != nil {
inner.Free()
body.Free()
return nil, err
}
inner.Free()
body.Free()
return innerPkt, nil
}
func (s *state) DecryptPacket(pkt *lob.Packet) (*lob.Packet, error) {
s.mtx.RLock()
defer s.mtx.RUnlock()
if !s.CanDecryptPacket() {
return nil, cipherset.ErrInvalidState
}
if pkt == nil {
return nil, nil
}
if !pkt.Header().IsZero() || pkt.BodyLen() < lenToken+lenNonce {
return nil, cipherset.ErrInvalidPacket
}
var (
nonce [lenNonce]byte
bodyRaw []byte
innerRaw []byte
innerPkt *lob.Packet
body = bufpool.New()
inner = bufpool.New()
ok bool
)
pkt.Body(body.SetLen(pkt.BodyLen()).RawBytes()[:0])
bodyRaw = body.RawBytes()
innerRaw = inner.RawBytes()
// compare token
if !bytes.Equal(bodyRaw[:lenToken], (*s.localToken)[:]) {
inner.Free()
body.Free()
return nil, cipherset.ErrInvalidPacket
}
// copy nonce
copy(nonce[:], bodyRaw[lenToken:lenToken+lenNonce])
// decrypt inner packet
innerRaw, ok = box.OpenAfterPrecomputation(
innerRaw[:0], bodyRaw[lenToken+lenNonce:], &nonce, s.lineDecryptionKey)
if !ok {
inner.Free()
body.Free()
return nil, cipherset.ErrInvalidPacket
}
inner.SetLen(len(innerRaw))
innerPkt, err := lob.Decode(inner)
if err != nil {
inner.Free()
body.Free()
return nil, err
}
inner.Free()
body.Free()
return innerPkt, nil
}
func (c *cipher) DecryptHandshake(localKey cipherset.Key, p []byte) (cipherset.Handshake, error) {
if len(p) < 21+4+4 {
return nil, cipherset.ErrInvalidMessage
}
var (
ctLen = len(p) - (21 + 4 + 4)
out = bufpool.New()
cs1aLocalKey, _ = localKey.(*key)
remoteKey *key
remoteLineKey *key
hshake *handshake
remoteLineKeyData = p[:21]
iv = p[21 : 21+4]
ciphertext = p[21+4 : 21+4+ctLen]
mac = p[21+4+ctLen:]
)
if cs1aLocalKey == nil {
return nil, cipherset.ErrInvalidState
}
{ // decrypt inner
ephemX, ephemY := eccp.Unmarshal(secp160r1.P160(), remoteLineKeyData)
if ephemX == nil || ephemY == nil {
return nil, cipherset.ErrInvalidMessage
}
shared := ecdh.ComputeShared(secp160r1.P160(), ephemX, ephemY, cs1aLocalKey.prv.d)
if shared == nil {
return nil, cipherset.ErrInvalidMessage
}
aharedSum := sha256.Sum256(shared)
aesKey := fold(aharedSum[:], 16)
if aesKey == nil {
return nil, cipherset.ErrInvalidMessage
}
aesBlock, err := aes.NewCipher(aesKey)
if err != nil {
return nil, cipherset.ErrInvalidMessage
}
var aesIv [16]byte
copy(aesIv[:], iv)
aes := Cipher.NewCTR(aesBlock, aesIv[:])
if aes == nil {
return nil, cipherset.ErrInvalidMessage
}
out.SetLen(ctLen)
aes.XORKeyStream(out.RawBytes(), ciphertext)
remoteLineKey = &key{}
remoteLineKey.pub.x, remoteLineKey.pub.y = ephemX, ephemY
}
{ // decode inner
inner, err := lob.Decode(out)
if err != nil {
return nil, cipherset.ErrInvalidMessage
}
at, hasAt := inner.Header().GetUint32("at")
if !hasAt {
return nil, cipherset.ErrInvalidMessage
}
delete(inner.Header().Extra, "at")
parts, err := cipherset.PartsFromHeader(inner.Header())
if err != nil {
return nil, cipherset.ErrInvalidMessage
}
if inner.BodyLen() != 21 {
return nil, cipherset.ErrInvalidMessage
}
remoteKey = &key{}
remoteKey.pub.x, remoteKey.pub.y = eccp.Unmarshal(secp160r1.P160(), inner.Body(nil))
if !remoteKey.CanEncrypt() {
return nil, cipherset.ErrInvalidMessage
}
hshake = &handshake{}
hshake.at = at
hshake.key = remoteKey
hshake.lineKey = remoteLineKey
hshake.parts = parts
}
{ // verify mac
var nonce [16]byte
copy(nonce[:], iv)
macKey := ecdh.ComputeShared(secp160r1.P160(),
remoteKey.pub.x, remoteKey.pub.y, cs1aLocalKey.prv.d)
macKey = append(macKey, nonce[:]...)
h := hmac.New(sha256.New, macKey)
h.Write(p[:21+4+ctLen])
if subtle.ConstantTimeCompare(mac, fold(h.Sum(nil), 4)) != 1 {
return nil, cipherset.ErrInvalidMessage
}
}
return hshake, nil
}
func (c *cipher) DecryptHandshake(localKey cipherset.Key, p []byte) (cipherset.Handshake, error) {
if len(p) < lenKey+lenNonce+lenAuth {
return nil, cipherset.ErrInvalidMessage
}
var (
ctLen = len(p) - (lenKey + lenNonce + lenAuth)
out = bufpool.New()
handshake = &handshake{}
cs3aLocalKey, _ = localKey.(*key)
at uint32
hasAt bool
mac [lenAuth]byte
nonce [lenNonce]byte
macKey [lenKey]byte
agreedKey [lenKey]byte
remoteKey [lenKey]byte
remoteLineKey [lenKey]byte
ciphertext []byte
ok bool
)
if cs3aLocalKey == nil {
return nil, cipherset.ErrInvalidState
}
copy(remoteLineKey[:], p[:lenKey])
copy(nonce[:], p[lenKey:lenKey+lenNonce])
copy(mac[:], p[lenKey+lenNonce+ctLen:])
ciphertext = p[lenKey+lenNonce : lenKey+lenNonce+ctLen]
// make agreedKey
box.Precompute(&agreedKey, &remoteLineKey, cs3aLocalKey.prv)
// decode BODY
outBuf, ok := box.OpenAfterPrecomputation(out.RawBytes(), ciphertext, &nonce, &agreedKey)
if !ok {
return nil, cipherset.ErrInvalidMessage
}
out.SetLen(len(outBuf))
{ // decode inner
inner, err := lob.Decode(out)
if err != nil {
return nil, cipherset.ErrInvalidMessage
}
at, hasAt = inner.Header().GetUint32("at")
if !hasAt {
return nil, cipherset.ErrInvalidMessage
}
delete(inner.Header().Extra, "at")
parts, err := cipherset.PartsFromHeader(inner.Header())
if err != nil {
return nil, cipherset.ErrInvalidMessage
}
if inner.BodyLen() != lenKey {
return nil, cipherset.ErrInvalidMessage
}
inner.Body(remoteKey[:0])
handshake.at = at
handshake.key = makeKey(nil, &remoteKey)
handshake.lineKey = makeKey(nil, &remoteLineKey)
handshake.parts = parts
}
{ // make macKey
box.Precompute(&macKey, &remoteKey, cs3aLocalKey.prv)
var (
sha = sha256.New()
)
sha.Write(p[lenKey : lenKey+lenNonce])
sha.Write(macKey[:])
sha.Sum(macKey[:0])
}
if !poly1305.Verify(&mac, p[:lenKey+lenNonce+ctLen], &macKey) {
return nil, cipherset.ErrInvalidMessage
}
return handshake, nil
}
