src/govpn/cmd/govpn-server/tcp.go

   1 /*
   2 GoVPN -- simple secure free software virtual private network daemon
   3 Copyright (C) 2014-2015 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         "time"
  26
  27         "govpn"
  28 )
  29
  30 func startTCP() {
  31         bind, err := net.ResolveTCPAddr("tcp", *bindAddr)
  32         if err != nil {
  33                 log.Fatalln("Can not resolve bind address:", err)
  34         }
  35         listener, err := net.ListenTCP("tcp", bind)
  36         if err != nil {
  37                 log.Fatalln("Can not listen on TCP:", err)
  38         }
  39         log.Println("Listening on TCP:" + *bindAddr)
  40         go func() {
  41                 for {
  42                         conn, err := listener.AcceptTCP()
  43                         if err != nil {
  44                                 log.Println("Error accepting TCP:", err)
  45                                 continue
  46                         }
  47                         go handleTCP(conn)
  48                 }
  49         }()
  50 }
  51
  52 func handleTCP(conn net.Conn) {
  53         addr := conn.RemoteAddr().String()
  54         buf := make([]byte, govpn.MTU)
  55         var n int
  56         var err error
  57         var prev int
  58         var hs *govpn.Handshake
  59         var ps *PeerState
  60         var peer *govpn.Peer
  61         var tap *govpn.TAP
  62         var conf *govpn.PeerConf
  63         for {
  64                 if prev == govpn.MTU {
  65                         break
  66                 }
  67                 conn.SetReadDeadline(time.Now().Add(time.Duration(govpn.TimeoutDefault) * time.Second))
  68                 n, err = conn.Read(buf[prev:])
  69                 if err != nil {
  70                         // Either EOFed or timeouted
  71                         break
  72                 }
  73                 prev += n
  74                 peerId := idsCache.Find(buf[:prev])
  75                 if peerId == nil {
  76                         continue
  77                 }
  78                 if hs == nil {
  79                         conf = confs[*peerId]
  80                         if conf == nil {
  81                                 log.Println("Can not get peer configuration:", peerId.String())
  82                                 break
  83                         }
  84                         hs = govpn.NewHandshake(addr, conn, conf)
  85                 }
  86                 peer = hs.Server(buf[:prev])
  87                 prev = 0
  88                 if peer == nil {
  89                         continue
  90                 }
  91                 hs.Zero()
  92                 log.Println("Peer handshake finished:", addr, peer.Id.String())
  93                 peersByIdLock.RLock()
  94                 addrPrev, exists := peersById[*peer.Id]
  95                 peersByIdLock.RUnlock()
  96                 if exists {
  97                         peersLock.Lock()
  98                         peers[addrPrev].terminator <- struct{}{}
  99                         tap = peers[addrPrev].tap
 100                         ps = &PeerState{
 101                                 peer:       peer,
 102                                 tap:        tap,
 103                                 terminator: make(chan struct{}),
 104                         }
 105                         go peerReady(*ps)
 106                         peersByIdLock.Lock()
 107                         kpLock.Lock()
 108                         delete(peers, addrPrev)
 109                         delete(knownPeers, addrPrev)
 110                         peers[addr] = ps
 111                         knownPeers[addr] = &peer
 112                         peersById[*peer.Id] = addr
 113                         peersLock.Unlock()
 114                         peersByIdLock.Unlock()
 115                         kpLock.Unlock()
 116                         log.Println("Rehandshake processed:", peer.Id.String())
 117                 } else {
 118                         ifaceName, err := callUp(peer.Id)
 119                         if err != nil {
 120                                 break
 121                         }
 122                         tap, err = govpn.TAPListen(ifaceName)
 123                         if err != nil {
 124                                 log.Println("Unable to create TAP:", err)
 125                                 break
 126                         }
 127                         ps = &PeerState{
 128                                 peer:       peer,
 129                                 tap:        tap,
 130                                 terminator: make(chan struct{}, 1),
 131                         }
 132                         go peerReady(*ps)
 133                         peersLock.Lock()
 134                         peersByIdLock.Lock()
 135                         kpLock.Lock()
 136                         peers[addr] = ps
 137                         peersById[*peer.Id] = addr
 138                         knownPeers[addr] = &peer
 139                         peersLock.Unlock()
 140                         peersByIdLock.Unlock()
 141                         kpLock.Unlock()
 142                         log.Println("Peer created:", peer.Id.String())
 143                 }
 144                 break
 145         }
 146         if hs != nil {
 147                 hs.Zero()
 148         }
 149         if peer == nil {
 150                 return
 151         }
 152
 153         nonceExpectation := make([]byte, govpn.NonceSize)
 154         peer.NonceExpectation(nonceExpectation)
 155         prev = 0
 156         var i int
 157         for {
 158                 if prev == govpn.MTU {
 159                         break
 160                 }
 161                 conn.SetReadDeadline(time.Now().Add(conf.Timeout))
 162                 n, err = conn.Read(buf[prev:])
 163                 if err != nil {
 164                         // Either EOFed or timeouted
 165                         break
 166                 }
 167                 prev += n
 168         CheckMore:
 169                 if prev < govpn.MinPktLength {
 170                         continue
 171                 }
 172                 i = bytes.Index(buf[:prev], nonceExpectation)
 173                 if i == -1 {
 174                         continue
 175                 }
 176                 if !peer.PktProcess(buf[:i+govpn.NonceSize], tap, false) {
 177                         log.Println(
 178                                 "Unauthenticated packet, dropping connection",
 179                                 addr, peer.Id.String(),
 180                         )
 181                         break
 182                 }
 183                 peer.NonceExpectation(nonceExpectation)
 184                 copy(buf, buf[i+govpn.NonceSize:prev])
 185                 prev = prev - i - govpn.NonceSize
 186                 goto CheckMore
 187         }
 188         peer.Zero()
 189 }