func doAuth(conn transports.PacketClient) bool {
// Authentication times out after 10 seconds.
timeout_ch := time.After(10 * time.Second)
send_ch := conn.SendChannel()
recv_ch := conn.RecvChannel()
// Receive the nonce from the server.
var nonce []byte
select {
case nonce = <-recv_ch:
// fallthrough
case <-timeout_ch:
log.Printf("Client authentication timed out: receiving nonce\n")
return false
}
hm := hmac.New(sha256.New, []byte(password))
_, err := hm.Write(nonce)
if err != nil {
log.Printf("Error computing HMAC: %s\n", err)
return false
}
resp := make([]byte, 64)
hex.Encode(resp, hm.Sum(nil))
select {
case send_ch <- resp:
// fallthrough
case <-timeout_ch:
log.Printf("Client authentication timed out: sending respond\n")
return false
}
// Wait for a response from the server.
var serv_resp []byte
select {
case serv_resp = <-recv_ch:
// fallthrough
case <-timeout_ch:
log.Printf("Client authentication timed out: waiting for confirmation\n")
return false
}
// Check response.
if bytes.Equal(serv_resp, []byte("success")) {
log.Printf("Authentication success\n")
return true
} else {
log.Printf("Authentication failure: %s\n", serv_resp)
return false
}
}
func startClient(tt tuntap.Device, hpserver string) {
defer tt.Close()
log.Printf("Holepunching with server %s...\n", hpserver)
methods := strings.Split(method, ",")
if len(methods) == 1 && methods[0] == "all" {
methods = []string{"tcp", "udp", "icmp", "dns"}
}
var conn transports.PacketClient
var err error
for _, m := range methods {
var curr_conn transports.PacketClient
err = nil
switch m {
case "tcp":
curr_conn, err = transports.NewTCPPacketClient(hpserver)
case "udp":
curr_conn, err = transports.NewUDPPacketClient(hpserver)
default:
log.Printf("Unknown method: %s\n", m)
continue
}
if err != nil {
log.Printf("Error creating transport '%s': %s\n", m, err)
continue
}
// Set up encryption.
enc_conn, err := transports.NewEncryptedPacketClient(curr_conn, "foobar")
if err != nil {
log.Printf("Could not initialize encryption: %s\n", err)
curr_conn.Close()
continue
}
// Encryption is valid, which means that we're authenticated.
conn = enc_conn
}
if conn == nil {
log.Printf("Could not create connection to server, exiting...\n")
return
}
log.Printf("Connected to server (reliable = %t)\n", conn.IsReliable())
recv_ch := conn.RecvChannel()
send_ch := conn.SendChannel()
defer conn.Close()
for {
// TODO: some way of stopping this
select {
case from_server := <-recv_ch:
log.Printf("server --> tuntap (%d bytes)\n", len(from_server))
tt.Write(from_server)
case from_tuntap := <-tt.RecvChannel():
log.Printf("tuntap --> server (%d bytes)\n", len(from_tuntap))
send_ch <- from_tuntap
case <-tt.EOFChannel():
log.Println("EOF received from TUN/TAP device, exiting...")
return
}
}
}