/
client-peer.go
171 lines (134 loc) · 3.09 KB
/
client-peer.go
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package ppe
import (
"bytes"
"crypto/rand"
"errors"
"io"
"golang.org/x/crypto/nacl/box"
)
type ClientPeer struct {
C *[32]byte
Cs *[32]byte
S *[32]byte
EC *[32]byte
ECs *[32]byte
handShakeBuf []byte
peer
}
func NewClientPeer(tr Transport, w io.Writer, r io.Reader, pkey *[32]byte, skey *[32]byte, serverpkey *[32]byte) Peer {
peer := &ClientPeer{}
peer.w = w
peer.r = r
peer.C = pkey
peer.Cs = skey
peer.S = serverpkey
peer.sharedKey = &[32]byte{}
peer.tr = tr
peer.assocID, _ = randomAssocID()
peer.nonce = 1
return peer
}
func (peer *ClientPeer) State() State {
return State{peer.S, peer.assocID, peer.nonce}
}
func (peer *ClientPeer) Close() error {
zero(peer.C)
zero(peer.Cs)
zero(peer.S)
zero(peer.EC)
zero(peer.ECs)
peer.peer.Close()
return nil
}
func (peer *ClientPeer) HandShake() error {
if peer.handshake {
return nil
}
peer.handshake = true
EC, ECs, err := box.GenerateKey(rand.Reader)
if err != nil {
return err
}
if peer.C == nil || peer.Cs == nil {
peer.C, peer.Cs, err = box.GenerateKey(rand.Reader)
if err != nil {
return err
}
}
Cnonce, err := NewNonce(append(EC[:], peer.S[:]...))
if err != nil {
return err
}
box.Precompute(peer.sharedKey, peer.S, ECs)
peer.initNonce = Cnonce
id, err := KeyID(peer.S[:])
if err != nil {
return err
}
if peer.tr == Packet {
peer.handShakeBuf = append(id, EC[:]...)
return nil
}
Ctag := make([]byte, 32)
if _, err = rand.Reader.Read(Ctag); err != nil {
return err
}
cryptbox := box.Seal(nil, Ctag, Cnonce.Read(peer.getNonce()), peer.S, ECs) // Box[Ctag](ECs -> S)
cryptbox = append(append(id, EC[:]...), cryptbox...)
if _, err = peer.WriteBlock(cryptbox); err != nil {
return err
}
buf, err := peer.ReadBlock()
if err != nil {
return err
}
cryptbox = buf
text, ok := box.Open(nil, cryptbox, Cnonce.Read(peer.getNonce()), peer.S, ECs)
if !ok {
return errors.New("Decryption failed")
}
ES := [32]byte{}
copy(ES[:], text[:32])
ctag := text[32:64]
if !bytes.Equal(Ctag, ctag) {
return errors.New("Bad Ctag")
}
Stag := text[64:]
message := peer.C[:]
nonce := Cnonce.Read(peer.getNonce())
v := box.Seal(nil, append(EC[:], Stag...), nonce, peer.S, peer.Cs) // V = Box[EC, Stag](Cs -> S)
message = append(message, v...)
cryptbox = box.Seal(nil, message, nonce, &ES, ECs) // Box[C,V](ECs -> ES)
if _, err = peer.WriteBlock(cryptbox); err != nil {
return err
}
box.Precompute(peer.sharedKey, &ES, ECs)
peer.initNonce = Cnonce
return nil
}
func (peer *ClientPeer) Write(p []byte) (n int, err error) {
err = peer.HandShake()
if err != nil {
return 0, err
}
if peer.tr == Packet {
if len(peer.handShakeBuf) == 0 {
return peer.peer.Write([]byte{}, p)
}
buf := peer.handShakeBuf
peer.handShakeBuf = []byte{}
n, err = peer.peer.Write(buf, p)
return
}
return peer.peer.Write([]byte{}, p)
}
func (peer *ClientPeer) Read(p []byte) (n int, err error) {
if peer.tr == Packet {
return peer.peer.Read([]byte{}, p)
}
err = peer.HandShake()
if err != nil {
return 0, err
}
return peer.peer.Read([]byte{}, p)
}