src/cypherpunks.ru/govpn/cmd/govpn-client/tcp.go

   1 /*
   2 GoVPN -- simple secure free software virtual private network daemon
   3 Copyright (C) 2014-2016 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, either version 3 of the License, or
   8 (at your option) any later version.
   9
  10 This program is distributed in the hope that it will be useful,
  11 but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13 GNU General Public License for more details.
  14
  15 You should have received a copy of the GNU General Public License
  16 along with this program.  If not, see <http://www.gnu.org/licenses/>.
  17 */
  18
  19 package main
  20
  21 import (
  22         "bytes"
  23         "log"
  24         "net"
  25         "sync/atomic"
  26         "time"
  27
  28         "cypherpunks.ru/govpn"
  29 )
  30
  31 func startTCP(timeouted, rehandshaking, termination chan struct{}) {
  32         remote, err := net.ResolveTCPAddr("tcp", *remoteAddr)
  33         if err != nil {
  34                 log.Fatalln("Can not resolve remote address:", err)
  35         }
  36         conn, err := net.DialTCP("tcp", nil, remote)
  37         if err != nil {
  38                 log.Fatalln("Can not connect to address:", err)
  39         }
  40         log.Println("Connected to TCP:" + *remoteAddr)
  41         handleTCP(conn, timeouted, rehandshaking, termination)
  42 }
  43
  44 func handleTCP(conn *net.TCPConn, timeouted, rehandshaking, termination chan struct{}) {
  45         hs := govpn.HandshakeStart(*remoteAddr, conn, conf)
  46         buf := make([]byte, 2*(govpn.EnclessEnlargeSize+*mtu)+*mtu)
  47         var n int
  48         var err error
  49         var prev int
  50         var peer *govpn.Peer
  51         var terminator chan struct{}
  52 HandshakeCycle:
  53         for {
  54                 select {
  55                 case <-termination:
  56                         break HandshakeCycle
  57                 default:
  58                 }
  59                 if prev == len(buf) {
  60                         log.Println("Timeouted waiting for the packet")
  61                         timeouted <- struct{}{}
  62                         break HandshakeCycle
  63                 }
  64
  65                 conn.SetReadDeadline(time.Now().Add(time.Duration(timeout) * time.Second))
  66                 n, err = conn.Read(buf[prev:])
  67                 if err != nil {
  68                         log.Println("Connection timeouted")
  69                         timeouted <- struct{}{}
  70                         break HandshakeCycle
  71                 }
  72
  73                 prev += n
  74                 peerId := idsCache.Find(buf[:prev])
  75                 if peerId == nil {
  76                         continue
  77                 }
  78                 peer = hs.Client(buf[:prev])
  79                 prev = 0
  80                 if peer == nil {
  81                         continue
  82                 }
  83                 log.Println("Handshake completed")
  84                 knownPeers = govpn.KnownPeers(map[string]**govpn.Peer{*remoteAddr: &peer})
  85                 if firstUpCall {
  86                         go govpn.ScriptCall(*upPath, *ifaceName, *remoteAddr)
  87                         firstUpCall = false
  88                 }
  89                 hs.Zero()
  90                 terminator = make(chan struct{})
  91                 go func() {
  92                         heartbeat := time.NewTicker(peer.Timeout)
  93                         var data []byte
  94                 Processor:
  95                         for {
  96                                 select {
  97                                 case <-heartbeat.C:
  98                                         peer.EthProcess(nil)
  99                                 case <-terminator:
 100                                         break Processor
 101                                 case data = <-tap.Sink:
 102                                         peer.EthProcess(data)
 103                                 }
 104                         }
 105                         heartbeat.Stop()
 106                         peer.Zero()
 107                 }()
 108                 break HandshakeCycle
 109         }
 110         if hs != nil {
 111                 hs.Zero()
 112         }
 113         if peer == nil {
 114                 return
 115         }
 116
 117         nonceExpectation := make([]byte, govpn.NonceSize)
 118         peer.NonceExpectation(nonceExpectation)
 119         prev = 0
 120         var i int
 121 TransportCycle:
 122         for {
 123                 select {
 124                 case <-termination:
 125                         break TransportCycle
 126                 default:
 127                 }
 128                 if prev == len(buf) {
 129                         log.Println("Timeouted waiting for the packet")
 130                         timeouted <- struct{}{}
 131                         break TransportCycle
 132                 }
 133                 conn.SetReadDeadline(time.Now().Add(time.Duration(timeout) * time.Second))
 134                 n, err = conn.Read(buf[prev:])
 135                 if err != nil {
 136                         log.Println("Connection timeouted")
 137                         timeouted <- struct{}{}
 138                         break TransportCycle
 139                 }
 140                 prev += n
 141         CheckMore:
 142                 if prev < govpn.MinPktLength {
 143                         continue
 144                 }
 145                 i = bytes.Index(buf[:prev], nonceExpectation)
 146                 if i == -1 {
 147                         continue
 148                 }
 149                 if !peer.PktProcess(buf[:i+govpn.NonceSize], tap, false) {
 150                         log.Println("Unauthenticated packet, dropping connection")
 151                         timeouted <- struct{}{}
 152                         break TransportCycle
 153                 }
 154                 if atomic.LoadUint64(&peer.BytesIn)+atomic.LoadUint64(&peer.BytesOut) > govpn.MaxBytesPerKey {
 155                         log.Println("Need rehandshake")
 156                         rehandshaking <- struct{}{}
 157                         break TransportCycle
 158                 }
 159                 peer.NonceExpectation(nonceExpectation)
 160                 copy(buf, buf[i+govpn.NonceSize:prev])
 161                 prev = prev - i - govpn.NonceSize
 162                 goto CheckMore
 163         }
 164         if terminator != nil {
 165                 terminator <- struct{}{}
 166         }
 167         peer.Zero()
 168         conn.Close()
 169 }