client/tcp.go

   1 /*
   2 GoVPN -- simple secure free software virtual private network daemon
   3 Copyright (C) 2014-2020 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         "bytes"
  22         "fmt"
  23         "net"
  24         "sync/atomic"
  25         "time"
  26
  27         "go.cypherpunks.ru/govpn/v7"
  28 )
  29
  30 func (c *Client) startTCP() {
  31         remote, err := net.ResolveTCPAddr("tcp", c.config.RemoteAddress)
  32         if err != nil {
  33                 c.Error <- fmt.Errorf("Can not resolve remote address: %s", err)
  34                 return
  35         }
  36         conn, err := net.DialTCP("tcp", nil, remote)
  37         if err != nil {
  38                 c.Error <- fmt.Errorf("Can not connect to address: %s", err)
  39                 return
  40         }
  41         govpn.Printf(`[connected remote="%s"]`, c.config.RemoteAddress)
  42         c.handleTCP(conn)
  43 }
  44
  45 func (c *Client) handleTCP(conn *net.TCPConn) {
  46         hs := govpn.HandshakeStart(c.config.RemoteAddress, conn, c.config.Peer)
  47         buf := make([]byte, 2*(govpn.EnclessEnlargeSize+c.config.MTU)+c.config.MTU)
  48         var n int
  49         var err error
  50         var prev int
  51         var peer *govpn.Peer
  52         var terminator chan struct{}
  53 HandshakeCycle:
  54         for {
  55                 select {
  56                 case <-c.termination:
  57                         break HandshakeCycle
  58                 default:
  59                 }
  60                 if prev == len(buf) {
  61                         govpn.Printf(`[packet-timeouted remote="%s"]`, c.config.RemoteAddress)
  62                         c.timeouted <- struct{}{}
  63                         break HandshakeCycle
  64                 }
  65
  66                 if err = conn.SetReadDeadline(time.Now().Add(c.config.Peer.Timeout)); err != nil {
  67                         c.Error <- err
  68                         break HandshakeCycle
  69                 }
  70                 n, err = conn.Read(buf[prev:])
  71                 if err != nil {
  72                         govpn.Printf(`[connection-timeouted remote="%s"]`, c.config.RemoteAddress)
  73                         c.timeouted <- struct{}{}
  74                         break HandshakeCycle
  75                 }
  76
  77                 prev += n
  78                 peerID := c.idsCache.Find(buf[:prev])
  79                 if peerID == nil {
  80                         continue
  81                 }
  82                 peer = hs.Client(buf[:prev])
  83                 prev = 0
  84                 if peer == nil {
  85                         continue
  86                 }
  87                 govpn.Printf(`[handshake-completed remote="%s"]`, c.config.RemoteAddress)
  88                 c.knownPeers.Store(c.config.RemoteAddress, &peer)
  89                 if c.firstUpCall {
  90                         go govpn.ScriptCall(c.config.UpPath, c.config.InterfaceName, c.config.RemoteAddress)
  91                         c.firstUpCall = false
  92                 }
  93                 hs.Zero()
  94                 terminator = make(chan struct{})
  95                 go govpn.PeerTapProcessor(peer, c.tap, terminator)
  96                 break HandshakeCycle
  97         }
  98         if hs != nil {
  99                 hs.Zero()
 100         }
 101         if peer == nil {
 102                 return
 103         }
 104
 105         prev = 0
 106         var i int
 107 TransportCycle:
 108         for {
 109                 select {
 110                 case <-c.termination:
 111                         break TransportCycle
 112                 default:
 113                 }
 114                 if prev == len(buf) {
 115                         govpn.Printf(`[packet-timeouted remote="%s"]`, c.config.RemoteAddress)
 116                         c.timeouted <- struct{}{}
 117                         break TransportCycle
 118                 }
 119                 if err = conn.SetReadDeadline(time.Now().Add(c.config.Peer.Timeout)); err != nil {
 120                         c.Error <- err
 121                         break TransportCycle
 122                 }
 123                 n, err = conn.Read(buf[prev:])
 124                 if err != nil {
 125                         govpn.Printf(`[connection-timeouted remote="%s"]`, c.config.RemoteAddress)
 126                         c.timeouted <- struct{}{}
 127                         break TransportCycle
 128                 }
 129                 prev += n
 130         CheckMore:
 131                 if prev < govpn.MinPktLength {
 132                         continue
 133                 }
 134                 i = bytes.Index(buf[:prev], peer.NonceExpect)
 135                 if i == -1 {
 136                         continue
 137                 }
 138                 if !peer.PktProcess(buf[:i+govpn.NonceSize], c.tap, false) {
 139                         govpn.Printf(`[packet-unauthenticated remote="%s"]`, c.config.RemoteAddress)
 140                         c.timeouted <- struct{}{}
 141                         break TransportCycle
 142                 }
 143                 if atomic.LoadUint64(&peer.BytesIn)+atomic.LoadUint64(&peer.BytesOut) > govpn.MaxBytesPerKey {
 144                         govpn.Printf(`[rehandshake-required remote="%s"]`, c.config.RemoteAddress)
 145                         c.rehandshaking <- struct{}{}
 146                         break TransportCycle
 147                 }
 148                 copy(buf, buf[i+govpn.NonceSize:prev])
 149                 prev = prev - i - govpn.NonceSize
 150                 goto CheckMore
 151         }
 152         if terminator != nil {
 153                 terminator <- struct{}{}
 154         }
 155         peer.Zero()
 156         if err = conn.Close(); err != nil {
 157                 c.Error <- err
 158         }
 159 }