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 // Handles stream encryption for inbound connections.
  31 func handleEncryption(
  32         rw io.ReadWriter,
  33         skeys mse.SecretKeyIter,
  34         policy HeaderObfuscationPolicy,
  35         selector mse.CryptoSelector,
  36 ) (
  37         ret io.ReadWriter,
  38         headerEncrypted bool,
  39         cryptoMethod mse.CryptoMethod,
  40         err error,
  41 ) {
  42         // Tries to start an unencrypted stream.
  43         if !policy.RequirePreferred || !policy.Preferred {
  44                 var protocol [len(pp.Protocol)]byte
  45                 _, err = io.ReadFull(rw, protocol[:])
  46                 if err != nil {
  47                         return
  48                 }
  49                 // Put the protocol back into the stream.
  50                 rw = struct {
  51                         io.Reader
  52                         io.Writer
  53                 }{
  54                         io.MultiReader(bytes.NewReader(protocol[:]), rw),
  55                         rw,
  56                 }
  57                 if string(protocol[:]) == pp.Protocol {
  58                         ret = rw
  59                         return
  60                 }
  61                 if policy.RequirePreferred {
  62                         // We are here because we require unencrypted connections.
  63                         err = fmt.Errorf("unexpected protocol string %q and header obfuscation disabled", protocol)
  64                         return
  65                 }
  66         }
  67         headerEncrypted = true
  68         ret, cryptoMethod, err = mse.ReceiveHandshake(rw, skeys, selector)
  69         return
  70 }
  71
  72 type PeerExtensionBits = pp.PeerExtensionBits