src/govpn/cmd/govpn-server/udp.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         "log"
  23         "net"
  24
  25         "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 chan []byte = 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         log.Println("Listening on UDP:" + *bindAddr)
  52
  53         udpBufs <- make([]byte, govpn.MTU)
  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 peer *govpn.Peer
  66                 var conf *govpn.PeerConf
  67                 for {
  68                         buf = <-udpBufs
  69                         n, raddr, err = conn.ReadFromUDP(buf)
  70                         if err != nil {
  71                                 log.Println("Unexpected error when receiving", err)
  72                                 break
  73                         }
  74                         addr = raddr.String()
  75
  76                         peersLock.RLock()
  77                         ps, exists = peers[addr]
  78                         peersLock.RUnlock()
  79                         if !exists {
  80                                 goto CheckHandshake
  81                         }
  82                         go func(ps *govpn.Peer, tap *govpn.TAP, buf []byte, n int) {
  83                                 peer.PktProcess(buf[:n], tap, true)
  84                                 udpBufs <- buf
  85                         }(ps.peer, ps.tap, buf, n)
  86                         continue
  87                 CheckHandshake:
  88                         hsLock.RLock()
  89                         hs, exists = handshakes[addr]
  90                         hsLock.RUnlock()
  91                         if !exists {
  92                                 goto CheckID
  93                         }
  94                         peer = hs.Server(buf[:n])
  95                         if peer == nil {
  96                                 goto Finished
  97                         }
  98
  99                         log.Println("Peer handshake finished:", addr, peer.Id.String())
 100                         hs.Zero()
 101                         hsLock.Lock()
 102                         delete(handshakes, addr)
 103                         hsLock.Unlock()
 104
 105                         go func() {
 106                                 udpBufs <- make([]byte, govpn.MTU)
 107                                 udpBufs <- make([]byte, govpn.MTU)
 108                         }()
 109                         peersByIdLock.RLock()
 110                         addrPrev, exists = peersById[*peer.Id]
 111                         peersByIdLock.RUnlock()
 112                         if exists {
 113                                 peersLock.RLock()
 114                                 ps = &PeerState{
 115                                         peer:       peer,
 116                                         tap:        peers[addrPrev].tap,
 117                                         terminator: peers[addrPrev].terminator,
 118                                 }
 119                                 peersLock.RUnlock()
 120                                 ps.terminator <- struct{}{}
 121                                 peersLock.Lock()
 122                                 peersByIdLock.Lock()
 123                                 kpLock.Lock()
 124                                 delete(peers, addrPrev)
 125                                 delete(knownPeers, addrPrev)
 126                                 delete(peersById, *peer.Id)
 127                                 peers[addr] = ps
 128                                 knownPeers[addr] = &peer
 129                                 peersById[*peer.Id] = addr
 130                                 peersLock.Unlock()
 131                                 peersByIdLock.Unlock()
 132                                 kpLock.Unlock()
 133                                 go func(ps PeerState) {
 134                                         peerReady(ps)
 135                                         <-udpBufs
 136                                         <-udpBufs
 137                                 }(*ps)
 138                                 log.Println("Rehandshake processed:", peer.Id.String())
 139                         } else {
 140                                 go func(addr string, peer *govpn.Peer) {
 141                                         ifaceName, err := callUp(peer.Id)
 142                                         if err != nil {
 143                                                 return
 144                                         }
 145                                         tap, err := govpn.TAPListen(ifaceName)
 146                                         if err != nil {
 147                                                 log.Println("Unable to create TAP:", err)
 148                                                 return
 149                                         }
 150                                         ps = &PeerState{
 151                                                 peer:       peer,
 152                                                 tap:        tap,
 153                                                 terminator: make(chan struct{}, 1),
 154                                         }
 155                                         go func(ps PeerState) {
 156                                                 peerReady(ps)
 157                                                 <-udpBufs
 158                                                 <-udpBufs
 159                                         }(*ps)
 160                                         peersLock.Lock()
 161                                         peersByIdLock.Lock()
 162                                         kpLock.Lock()
 163                                         peers[addr] = ps
 164                                         knownPeers[addr] = &peer
 165                                         peersById[*peer.Id] = addr
 166                                         peersLock.Unlock()
 167                                         peersByIdLock.Unlock()
 168                                         kpLock.Unlock()
 169                                         log.Println("Peer created:", peer.Id.String())
 170                                 }(addr, peer)
 171                         }
 172                         goto Finished
 173                 CheckID:
 174                         peerId = govpn.IDsCache.Find(buf[:n])
 175                         if peerId == nil {
 176                                 log.Println("Unknown identity from:", addr)
 177                                 goto Finished
 178                         }
 179                         conf = peerId.Conf()
 180                         if conf == nil {
 181                                 log.Println("Unable to get peer configuration:", peerId.String())
 182                                 goto Finished
 183                         }
 184                         hs = govpn.NewHandshake(
 185                                 addr,
 186                                 UDPSender{conn: conn, addr: raddr},
 187                                 conf,
 188                         )
 189                         hs.Server(buf[:n])
 190                         hsLock.Lock()
 191                         handshakes[addr] = hs
 192                         hsLock.Unlock()
 193                 Finished:
 194                         udpBufs <- buf
 195                 }
 196         }()
 197 }