src/cypherpunks.ru/govpn/client/udp.go

   1 /*
   2 GoVPN -- simple secure free software virtual private network daemon
   3 Copyright (C) 2014-2019 Sergey Matveev <stargrave@stargrave.org>
   4
   5 This program is free software: you can redistribute it and/or modify
   6 it under the terms of the GNU General Public License as published by
   7 the Free Software Foundation, version 3 of the License.
   8
   9 This program is distributed in the hope that it will be useful,
  10 but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 GNU General Public License for more details.
  13
  14 You should have received a copy of the GNU General Public License
  15 along with this program.  If not, see <http://www.gnu.org/licenses/>.
  16 */
  17
  18 package client
  19
  20 import (
  21         "fmt"
  22         "net"
  23         "sync/atomic"
  24         "time"
  25
  26         "cypherpunks.ru/govpn"
  27 )
  28
  29 func (c *Client) startUDP() {
  30         remote, err := net.ResolveUDPAddr("udp", c.config.RemoteAddress)
  31         if err != nil {
  32                 c.Error <- fmt.Errorf("Can not resolve remote address: %s", err)
  33                 return
  34         }
  35         conn, err := net.DialUDP("udp", nil, remote)
  36         if err != nil {
  37                 c.Error <- fmt.Errorf("Can not connect remote address: %s", err)
  38                 return
  39         }
  40         govpn.Printf(`[connected remote="%s"]`, c.config.RemoteAddress)
  41
  42         hs := govpn.HandshakeStart(c.config.RemoteAddress, conn, c.config.Peer)
  43         buf := make([]byte, c.config.MTU*2)
  44         var n int
  45         var timeouts int
  46         var peer *govpn.Peer
  47         var terminator chan struct{}
  48         timeout := int(c.config.Peer.Timeout.Seconds())
  49 MainCycle:
  50         for {
  51                 select {
  52                 case <-c.termination:
  53                         break MainCycle
  54                 default:
  55                 }
  56
  57                 if err = conn.SetReadDeadline(time.Now().Add(time.Second)); err != nil {
  58                         c.Error <- err
  59                         break MainCycle
  60                 }
  61                 n, err = conn.Read(buf)
  62                 if timeouts == timeout {
  63                         govpn.Printf(`[connection-timeouted remote="%s"]`, c.config.RemoteAddress)
  64                         c.timeouted <- struct{}{}
  65                         break
  66                 }
  67                 if err != nil {
  68                         timeouts++
  69                         continue
  70                 }
  71                 if peer != nil {
  72                         if peer.PktProcess(buf[:n], c.tap, true) {
  73                                 timeouts = 0
  74                         } else {
  75                                 govpn.Printf(`[packet-unauthenticated remote="%s"]`, c.config.RemoteAddress)
  76                                 timeouts++
  77                         }
  78                         if atomic.LoadUint64(&peer.BytesIn)+atomic.LoadUint64(&peer.BytesOut) > govpn.MaxBytesPerKey {
  79                                 govpn.Printf(`[rehandshake-required remote="%s"]`, c.config.RemoteAddress)
  80                                 c.rehandshaking <- struct{}{}
  81                                 break MainCycle
  82                         }
  83                         continue
  84                 }
  85                 if c.idsCache.Find(buf[:n]) == nil {
  86                         govpn.Printf(`[identity-invalid remote="%s"]`, c.config.RemoteAddress)
  87                         continue
  88                 }
  89                 timeouts = 0
  90                 peer = hs.Client(buf[:n])
  91                 if peer == nil {
  92                         continue
  93                 }
  94                 govpn.Printf(`[handshake-completed remote="%s"]`, c.config.RemoteAddress)
  95                 c.knownPeers.Store(c.config.RemoteAddress, &peer)
  96                 if c.firstUpCall {
  97                         go govpn.ScriptCall(c.config.UpPath, c.config.InterfaceName, c.config.RemoteAddress)
  98                         c.firstUpCall = false
  99                 }
 100                 hs.Zero()
 101                 terminator = make(chan struct{})
 102                 go govpn.PeerTapProcessor(peer, c.tap, terminator)
 103         }
 104         if terminator != nil {
 105                 terminator <- struct{}{}
 106         }
 107         if hs != nil {
 108                 hs.Zero()
 109         }
 110         if err = conn.Close(); err != nil {
 111                 c.Error <- err
 112         }
 113 }