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