cmd/govpn-server/udp.go

   1 /*
   2 GoVPN -- simple secure free software virtual private network daemon
   3 Copyright (C) 2014-2020 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, version 3 of the License.
   8
   9 This program is distributed in the hope that it will be useful,
  10 but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 GNU General Public License for more details.
  13
  14 You should have received a copy of the GNU General Public License
  15 along with this program.  If not, see <http://www.gnu.org/licenses/>.
  16 */
  17
  18 package main
  19
  20 import (
  21         "log"
  22         "net"
  23
  24         "go.cypherpunks.ru/govpn/v7"
  25 )
  26
  27 type UDPSender struct {
  28         conn *net.UDPConn
  29         addr *net.UDPAddr
  30 }
  31
  32 func (c UDPSender) Write(data []byte) (int, error) {
  33         return c.conn.WriteToUDP(data, c.addr)
  34 }
  35
  36 var (
  37         // Buffers for UDP parallel processing
  38         udpBufs = make(chan []byte, 1<<8)
  39 )
  40
  41 func startUDP() {
  42         bind, err := net.ResolveUDPAddr("udp", *bindAddr)
  43         if err != nil {
  44                 log.Fatalln("Can not resolve bind address:", err)
  45         }
  46         conn, err := net.ListenUDP("udp", bind)
  47         if err != nil {
  48                 log.Fatalln("Can not listen on UDP:", err)
  49         }
  50         govpn.BothPrintf(`[udp-listen bind="%s"]`, *bindAddr)
  51
  52         udpBufs <- make([]byte, govpn.MTUMax)
  53         go func() {
  54                 var buf []byte
  55                 var raddr *net.UDPAddr
  56                 var addr string
  57                 var n int
  58                 var err error
  59                 var exists bool
  60                 var psI interface{}
  61                 var ps *PeerState
  62                 var hsI interface{}
  63                 var hs *govpn.Handshake
  64                 var addrPrevI interface{}
  65                 var addrPrev string
  66                 var peerPrevI interface{}
  67                 var peerPrev *PeerState
  68                 var peerID *govpn.PeerID
  69                 var conf *govpn.PeerConf
  70                 for {
  71                         buf = <-udpBufs
  72                         n, raddr, err = conn.ReadFromUDP(buf)
  73                         if err != nil {
  74                                 govpn.Printf(`[receive-failed bind="%s" err="%s"]`, *bindAddr, err)
  75                                 break
  76                         }
  77                         addr = raddr.String()
  78
  79                         psI, exists = peers.Load(addr)
  80                         if exists {
  81                                 ps = psI.(*PeerState)
  82                                 go func(peer *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                         }
  88
  89                         hsI, exists = handshakes.Load(addr)
  90                         if !exists {
  91                                 peerID = idsCache.Find(buf[:n])
  92                                 if peerID == nil {
  93                                         govpn.Printf(`[identity-unknown bind="%s" addr="%s"]`, *bindAddr, addr)
  94                                         udpBufs <- buf
  95                                         continue
  96                                 }
  97                                 conf = confs[*peerID]
  98                                 if conf == nil {
  99                                         govpn.Printf(
 100                                                 `[conf-get-failed bind="%s" peer="%s"]`,
 101                                                 *bindAddr, peerID.String(),
 102                                         )
 103                                         udpBufs <- buf
 104                                         continue
 105                                 }
 106                                 hs := govpn.NewHandshake(
 107                                         addr,
 108                                         UDPSender{conn: conn, addr: raddr},
 109                                         conf,
 110                                 )
 111                                 hs.Server(buf[:n])
 112                                 udpBufs <- buf
 113                                 handshakes.Store(addr, hs)
 114                                 continue
 115                         }
 116
 117                         hs = hsI.(*govpn.Handshake)
 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                         handshakes.Delete(addr)
 129
 130                         go func() {
 131                                 udpBufs <- make([]byte, govpn.MTUMax)
 132                                 udpBufs <- make([]byte, govpn.MTUMax)
 133                         }()
 134                         addrPrevI, exists = peersByID.Load(*peer.ID)
 135                         if exists {
 136                                 addrPrev = addrPrevI.(string)
 137                                 peerPrevI, exists = peers.Load(addrPrev)
 138                                 if exists {
 139                                         peerPrev = peerPrevI.(*PeerState)
 140                                         exists = peerPrev == nil
 141                                 }
 142                         }
 143                         if exists {
 144                                 peerPrev.terminator <- struct{}{}
 145                                 psNew := &PeerState{
 146                                         peer:       peer,
 147                                         tap:        peerPrev.tap,
 148                                         terminator: make(chan struct{}),
 149                                 }
 150                                 go func(peer *govpn.Peer, tap *govpn.TAP, terminator chan struct{}) {
 151                                         govpn.PeerTapProcessor(peer, tap, terminator)
 152                                         <-udpBufs
 153                                         <-udpBufs
 154                                 }(psNew.peer, psNew.tap, psNew.terminator)
 155                                 peers.Delete(addrPrev)
 156                                 peers.Store(addr, psNew)
 157                                 knownPeers.Delete(addrPrev)
 158                                 knownPeers.Store(addr, &peer)
 159                                 peersByID.Store(*peer.ID, addr)
 160                                 govpn.Printf(
 161                                         `[rehandshake-completed bind="%s" peer="%s"]`,
 162                                         *bindAddr, peer.ID.String(),
 163                                 )
 164                         } else {
 165                                 go func(addr string, peer *govpn.Peer) {
 166                                         ifaceName, err := callUp(peer.ID, peer.Addr)
 167                                         if err != nil {
 168                                                 return
 169                                         }
 170                                         tap, err := govpn.TAPListen(ifaceName, peer.MTU)
 171                                         if err != nil {
 172                                                 govpn.Printf(
 173                                                         `[tap-failed bind="%s" peer="%s" err="%s"]`,
 174                                                         *bindAddr, peer.ID.String(), err,
 175                                                 )
 176                                                 return
 177                                         }
 178                                         psNew := &PeerState{
 179                                                 peer:       peer,
 180                                                 tap:        tap,
 181                                                 terminator: make(chan struct{}),
 182                                         }
 183                                         go func(peer *govpn.Peer, tap *govpn.TAP, terminator chan struct{}) {
 184                                                 govpn.PeerTapProcessor(peer, tap, terminator)
 185                                                 <-udpBufs
 186                                                 <-udpBufs
 187                                         }(psNew.peer, psNew.tap, psNew.terminator)
 188                                         peers.Store(addr, psNew)
 189                                         knownPeers.Store(addr, &peer)
 190                                         peersByID.Store(*peer.ID, addr)
 191                                         govpn.Printf(
 192                                                 `[peer-created bind="%s" peer="%s"]`,
 193                                                 *bindAddr,
 194                                                 peer.ID.String(),
 195                                         )
 196                                 }(addr, peer)
 197                         }
 198                         udpBufs <- buf
 199                 }
 200         }()
 201 }