-// Convert a net.Addr to its compact IP representation. Either 4 or 16 bytes
-// per "yourip" field of http://www.bittorrent.org/beps/bep_0010.html.
-func addrCompactIP(addr net.Addr) (string, error) {
- host, _, err := net.SplitHostPort(addr.String())
- if err != nil {
- return "", err
- }
- ip := net.ParseIP(host)
- if v4 := ip.To4(); v4 != nil {
- if len(v4) != 4 {
- panic(v4)
- }
- return string(v4), nil
- }
- return string(ip.To16()), nil
-}
-
-func handshakeWriter(w io.Writer, bb <-chan []byte, done chan<- error) {
- var err error
- for b := range bb {
- _, err = w.Write(b)
- if err != nil {
- break
- }
- }
- done <- err
-}
-
-type (
- peerExtensionBytes [8]byte
- peerID [20]byte
-)
-
-func (pex *peerExtensionBytes) SupportsExtended() bool {
- return pex[5]&0x10 != 0
-}
-
-func (pex *peerExtensionBytes) SupportsDHT() bool {
- return pex[7]&0x01 != 0
-}
-
-func (pex *peerExtensionBytes) SupportsFast() bool {
- return pex[7]&0x04 != 0
-}
-
-type handshakeResult struct {
- peerExtensionBytes
- peerID
- metainfo.Hash
-}
-
-// ih is nil if we expect the peer to declare the InfoHash, such as when the
-// peer initiated the connection. Returns ok if the handshake was successful,
-// and err if there was an unexpected condition other than the peer simply
-// abandoning the handshake.
-func handshake(sock io.ReadWriter, ih *metainfo.Hash, peerID [20]byte, extensions peerExtensionBytes) (res handshakeResult, ok bool, err error) {
- // Bytes to be sent to the peer. Should never block the sender.
- postCh := make(chan []byte, 4)
- // A single error value sent when the writer completes.
- writeDone := make(chan error, 1)
- // Performs writes to the socket and ensures posts don't block.
- go handshakeWriter(sock, postCh, writeDone)
-
- defer func() {
- close(postCh) // Done writing.
- if !ok {
- return
- }
- if err != nil {
- panic(err)
- }
- // Wait until writes complete before returning from handshake.
- err = <-writeDone
- if err != nil {
- err = fmt.Errorf("error writing: %s", err)
- }
- }()
-
- post := func(bb []byte) {
- select {
- case postCh <- bb:
- default:
- panic("mustn't block while posting")
- }
- }
-
- post([]byte(pp.Protocol))
- post(extensions[:])
- if ih != nil { // We already know what we want.
- post(ih[:])
- post(peerID[:])
- }
- var b [68]byte
- _, err = io.ReadFull(sock, b[:68])
- if err != nil {
- err = nil
- return
- }
- if string(b[:20]) != pp.Protocol {
- return
- }
- missinggo.CopyExact(&res.peerExtensionBytes, b[20:28])
- missinggo.CopyExact(&res.Hash, b[28:48])
- missinggo.CopyExact(&res.peerID, b[48:68])
- peerExtensions.Add(hex.EncodeToString(res.peerExtensionBytes[:]), 1)
-
- // TODO: Maybe we can just drop peers here if we're not interested. This
- // could prevent them trying to reconnect, falsely believing there was
- // just a problem.
- if ih == nil { // We were waiting for the peer to tell us what they wanted.
- post(res.Hash[:])
- post(peerID[:])
- }
-
- ok = true
- return
-}
-
-// Wraps a raw connection and provides the interface we want for using the
-// connection in the message loop.
-type deadlineReader struct {
- nc net.Conn
- r io.Reader
-}
-
-func (r deadlineReader) Read(b []byte) (int, error) {
- // Keep-alives should be received every 2 mins. Give a bit of gracetime.
- err := r.nc.SetReadDeadline(time.Now().Add(150 * time.Second))
- if err != nil {
- return 0, fmt.Errorf("error setting read deadline: %s", err)
- }
- return r.r.Read(b)
-}
-
-func handleEncryption(
- rw io.ReadWriter,
- skeys mse.SecretKeyIter,
- policy EncryptionPolicy,
-) (
- ret io.ReadWriter,
- headerEncrypted bool,
- cryptoMethod uint32,
- err error,
-) {
- if !policy.ForceEncryption {
- var protocol [len(pp.Protocol)]byte
- _, err = io.ReadFull(rw, protocol[:])
- if err != nil {
- return
- }
- rw = struct {
- io.Reader
- io.Writer
- }{
- io.MultiReader(bytes.NewReader(protocol[:]), rw),
- rw,
- }
- if string(protocol[:]) == pp.Protocol {
- ret = rw
- return
- }
- }
- headerEncrypted = true
- ret, err = mse.ReceiveHandshake(rw, skeys, func(provides uint32) uint32 {
- cryptoMethod = func() uint32 {
- switch {
- case policy.ForceEncryption:
- return mse.CryptoMethodRC4
- case policy.DisableEncryption:
- return mse.CryptoMethodPlaintext
- case policy.PreferNoEncryption && provides&mse.CryptoMethodPlaintext != 0:
- return mse.CryptoMethodPlaintext
- default:
- return mse.DefaultCryptoSelector(provides)
- }
- }()
- return cryptoMethod
- })
- return
-}
-