src/cypherpunks.ru/govpn/cmd/govpn-server/udp.go

   1 /*
   2 GoVPN -- simple secure free software virtual private network daemon
   3 Copyright (C) 2014-2017 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         "log"
  23         "net"
  24
  25         "cypherpunks.ru/govpn"
  26 )
  27
  28 type UDPSender struct {
  29         conn *net.UDPConn
  30         addr *net.UDPAddr
  31 }
  32
  33 func (c UDPSender) Write(data []byte) (int, error) {
  34         return c.conn.WriteToUDP(data, c.addr)
  35 }
  36
  37 var (
  38         // Buffers for UDP parallel processing
  39         udpBufs = make(chan []byte, 1<<8)
  40 )
  41
  42 func startUDP() {
  43         bind, err := net.ResolveUDPAddr("udp", *bindAddr)
  44         if err != nil {
  45                 log.Fatalln("Can not resolve bind address:", err)
  46         }
  47         conn, err := net.ListenUDP("udp", bind)
  48         if err != nil {
  49                 log.Fatalln("Can not listen on UDP:", err)
  50         }
  51         govpn.BothPrintf(`[udp-listen bind="%s"]`, *bindAddr)
  52
  53         udpBufs <- make([]byte, govpn.MTUMax)
  54         go func() {
  55                 var buf []byte
  56                 var raddr *net.UDPAddr
  57                 var addr string
  58                 var n int
  59                 var err error
  60                 var ps *PeerState
  61                 var hs *govpn.Handshake
  62                 var addrPrev string
  63                 var exists bool
  64                 var peerID *govpn.PeerID
  65                 var conf *govpn.PeerConf
  66                 for {
  67                         buf = <-udpBufs
  68                         n, raddr, err = conn.ReadFromUDP(buf)
  69                         if err != nil {
  70                                 govpn.Printf(`[receive-failed bind="%s" err="%s"]`, *bindAddr, err)
  71                                 break
  72                         }
  73                         addr = raddr.String()
  74
  75                         peersLock.RLock()
  76                         ps, exists = peers[addr]
  77                         peersLock.RUnlock()
  78                         if exists {
  79                                 go func(peer *govpn.Peer, tap *govpn.TAP, buf []byte, n int) {
  80                                         peer.PktProcess(buf[:n], tap, true)
  81                                         udpBufs <- buf
  82                                 }(ps.peer, ps.tap, buf, n)
  83                                 continue
  84                         }
  85
  86                         hsLock.RLock()
  87                         hs, exists = handshakes[addr]
  88                         hsLock.RUnlock()
  89                         if !exists {
  90                                 peerID = idsCache.Find(buf[:n])
  91                                 if peerID == nil {
  92                                         govpn.Printf(`[identity-unknown bind="%s" addr="%s"]`, *bindAddr, addr)
  93                                         udpBufs <- buf
  94                                         continue
  95                                 }
  96                                 conf = confs[*peerID]
  97                                 if conf == nil {
  98                                         govpn.Printf(
  99                                                 `[conf-get-failed bind="%s" peer="%s"]`,
 100                                                 *bindAddr, peerID.String(),
 101                                         )
 102                                         udpBufs <- buf
 103                                         continue
 104                                 }
 105                                 hs := govpn.NewHandshake(
 106                                         addr,
 107                                         UDPSender{conn: conn, addr: raddr},
 108                                         conf,
 109                                 )
 110                                 hs.Server(buf[:n])
 111                                 udpBufs <- buf
 112                                 hsLock.Lock()
 113                                 handshakes[addr] = hs
 114                                 hsLock.Unlock()
 115                                 continue
 116                         }
 117
 118                         peer := hs.Server(buf[:n])
 119                         if peer == nil {
 120                                 udpBufs <- buf
 121                                 continue
 122                         }
 123                         govpn.Printf(
 124                                 `[handshake-completed bind="%s" addr="%s" peer="%s"]`,
 125                                 *bindAddr, addr, peerID.String(),
 126                         )
 127                         hs.Zero()
 128                         hsLock.Lock()
 129                         delete(handshakes, addr)
 130                         hsLock.Unlock()
 131
 132                         go func() {
 133                                 udpBufs <- make([]byte, govpn.MTUMax)
 134                                 udpBufs <- make([]byte, govpn.MTUMax)
 135                         }()
 136                         peersByIDLock.RLock()
 137                         addrPrev, exists = peersByID[*peer.ID]
 138                         peersByIDLock.RUnlock()
 139                         var peerPrev *PeerState
 140                         if exists {
 141                                 peersLock.Lock()
 142                                 peerPrev = peers[addrPrev]
 143                                 if peerPrev == nil {
 144                                         exists = false
 145                                         peersLock.Unlock()
 146                                 }
 147                         }
 148                         if exists {
 149                                 peerPrev.terminator <- struct{}{}
 150                                 psNew := &PeerState{
 151                                         peer:       peer,
 152                                         tap:        peerPrev.tap,
 153                                         terminator: make(chan struct{}),
 154                                 }
 155                                 go func(peer *govpn.Peer, tap *govpn.TAP, terminator chan struct{}) {
 156                                         govpn.PeerTapProcessor(peer, tap, terminator)
 157                                         <-udpBufs
 158                                         <-udpBufs
 159                                 }(psNew.peer, psNew.tap, psNew.terminator)
 160                                 peersByIDLock.Lock()
 161                                 kpLock.Lock()
 162                                 delete(peers, addrPrev)
 163                                 delete(knownPeers, addrPrev)
 164                                 peers[addr] = psNew
 165                                 knownPeers[addr] = &peer
 166                                 peersByID[*peer.ID] = addr
 167                                 peersLock.Unlock()
 168                                 peersByIDLock.Unlock()
 169                                 kpLock.Unlock()
 170                                 govpn.Printf(
 171                                         `[rehandshake-completed bind="%s" peer="%s"]`,
 172                                         *bindAddr, peer.ID.String(),
 173                                 )
 174                         } else {
 175                                 go func(addr string, peer *govpn.Peer) {
 176                                         ifaceName, err := callUp(peer.ID, peer.Addr)
 177                                         if err != nil {
 178                                                 return
 179                                         }
 180                                         tap, err := govpn.TAPListen(ifaceName, peer.MTU)
 181                                         if err != nil {
 182                                                 govpn.Printf(
 183                                                         `[tap-failed bind="%s" peer="%s" err="%s"]`,
 184                                                         *bindAddr, peer.ID.String(), err,
 185                                                 )
 186                                                 return
 187                                         }
 188                                         psNew := &PeerState{
 189                                                 peer:       peer,
 190                                                 tap:        tap,
 191                                                 terminator: make(chan struct{}),
 192                                         }
 193                                         go func(peer *govpn.Peer, tap *govpn.TAP, terminator chan struct{}) {
 194                                                 govpn.PeerTapProcessor(peer, tap, terminator)
 195                                                 <-udpBufs
 196                                                 <-udpBufs
 197                                         }(psNew.peer, psNew.tap, psNew.terminator)
 198                                         peersLock.Lock()
 199                                         peersByIDLock.Lock()
 200                                         kpLock.Lock()
 201                                         peers[addr] = psNew
 202                                         knownPeers[addr] = &peer
 203                                         peersByID[*peer.ID] = addr
 204                                         peersLock.Unlock()
 205                                         peersByIDLock.Unlock()
 206                                         kpLock.Unlock()
 207                                         govpn.Printf(
 208                                                 `[peer-created bind="%s" peer="%s"]`,
 209                                                 *bindAddr,
 210                                                 peer.ID.String(),
 211                                         )
 212                                 }(addr, peer)
 213                         }
 214                         udpBufs <- buf
 215                 }
 216         }()
 217 }