handshake.go

   1 package torrent
   2
   3 import (
   4         "bytes"
   5         "fmt"
   6         "io"
   7         "net"
   8         "time"
   9
  10         "github.com/anacrolix/torrent/mse"
  11         pp "github.com/anacrolix/torrent/peer_protocol"
  12 )
  13
  14 // Wraps a raw connection and provides the interface we want for using the
  15 // connection in the message loop.
  16 type deadlineReader struct {
  17         nc net.Conn
  18         r  io.Reader
  19 }
  20
  21 func (r deadlineReader) Read(b []byte) (int, error) {
  22         // Keep-alives should be received every 2 mins. Give a bit of gracetime.
  23         err := r.nc.SetReadDeadline(time.Now().Add(150 * time.Second))
  24         if err != nil {
  25                 return 0, fmt.Errorf("error setting read deadline: %s", err)
  26         }
  27         return r.r.Read(b)
  28 }
  29
  30 func handleEncryption(
  31         rw io.ReadWriter,
  32         skeys mse.SecretKeyIter,
  33         policy EncryptionPolicy,
  34 ) (
  35         ret io.ReadWriter,
  36         headerEncrypted bool,
  37         cryptoMethod mse.CryptoMethod,
  38         err error,
  39 ) {
  40         if !policy.ForceEncryption {
  41                 var protocol [len(pp.Protocol)]byte
  42                 _, err = io.ReadFull(rw, protocol[:])
  43                 if err != nil {
  44                         return
  45                 }
  46                 rw = struct {
  47                         io.Reader
  48                         io.Writer
  49                 }{
  50                         io.MultiReader(bytes.NewReader(protocol[:]), rw),
  51                         rw,
  52                 }
  53                 if string(protocol[:]) == pp.Protocol {
  54                         ret = rw
  55                         return
  56                 }
  57         }
  58         headerEncrypted = true
  59         ret, cryptoMethod, err = mse.ReceiveHandshake(rw, skeys, func(provides mse.CryptoMethod) mse.CryptoMethod {
  60                 switch {
  61                 case policy.ForceEncryption:
  62                         return mse.CryptoMethodRC4
  63                 case policy.DisableEncryption:
  64                         return mse.CryptoMethodPlaintext
  65                 case policy.PreferNoEncryption && provides&mse.CryptoMethodPlaintext != 0:
  66                         return mse.CryptoMethodPlaintext
  67                 default:
  68                         return mse.DefaultCryptoSelector(provides)
  69                 }
  70         })
  71         return
  72 }
  73
  74 type PeerExtensionBits = pp.PeerExtensionBits