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Always return errors when handshakes or dialing fails 

I intend to use xerrors-style error handling for special cases.
This commit is contained in:
Matt Joiner 2019-07-19 16:15:46 +10:00
parent 63d215568a
commit 338287486f
5 changed files with 41 additions and 44 deletions
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66
client.go
View File

@ -37,6 +37,7 @@ import (
"github.com/dustin/go-humanize"
"github.com/google/btree"
"golang.org/x/time/rate"
"golang.org/x/xerrors"
)
// Clients contain zero or more Torrents. A Client manages a blocklist, the
@ -617,16 +618,13 @@ func (cl *Client) handshakesConnection(ctx context.Context, nc net.Conn, t *Torr
if err != nil {
panic(err)
}
ok, err = cl.initiateHandshakes(c, t)
if !ok {
c = nil
}
err = cl.initiateHandshakes(c, t)
return
}
// Returns nil connection and nil error if no connection could be established
// for valid reasons.
func (cl *Client) establishOutgoingConnEx(t *Torrent, addr IpPort, obfuscatedHeader bool) (c *connection, err error) {
func (cl *Client) establishOutgoingConnEx(t *Torrent, addr IpPort, obfuscatedHeader bool) (*connection, error) {
ctx, cancel := context.WithTimeout(context.Background(), func() time.Duration {
cl.rLock()
defer cl.rUnlock()
@ -636,14 +634,16 @@ func (cl *Client) establishOutgoingConnEx(t *Torrent, addr IpPort, obfuscatedHea
dr := cl.dialFirst(ctx, addr.String())
nc := dr.Conn
if nc == nil {
return
}
defer func() {
if c == nil || err != nil {
nc.Close()
if ctx.Err() != nil {
return nil, ctx.Err()
}
}()
return cl.handshakesConnection(ctx, nc, t, obfuscatedHeader, addr, dr.Network)
return nil, errors.New("dial failed")
}
c, err := cl.handshakesConnection(ctx, nc, t, obfuscatedHeader, addr, dr.Network)
if err != nil {
nc.Close()
}
return c, err
}
// Returns nil connection and nil error if no connection could be established
@ -652,13 +652,11 @@ func (cl *Client) establishOutgoingConn(t *Torrent, addr IpPort) (c *connection,
torrent.Add("establish outgoing connection", 1)
obfuscatedHeaderFirst := cl.config.HeaderObfuscationPolicy.Preferred
c, err = cl.establishOutgoingConnEx(t, addr, obfuscatedHeaderFirst)
if err != nil {
//cl.logger.Printf("error establish connection to %s (obfuscatedHeader=%t): %v", addr, obfuscatedHeaderFirst, err)
}
if c != nil {
if err == nil {
torrent.Add("initiated conn with preferred header obfuscation", 1)
return
}
//cl.logger.Printf("error establishing connection to %s (obfuscatedHeader=%t): %v", addr, obfuscatedHeaderFirst, err)
if cl.config.HeaderObfuscationPolicy.RequirePreferred {
// We should have just tried with the preferred header obfuscation. If it was required,
// there's nothing else to try.
@ -666,9 +664,10 @@ func (cl *Client) establishOutgoingConn(t *Torrent, addr IpPort) (c *connection,
}
// Try again with encryption if we didn't earlier, or without if we did.
c, err = cl.establishOutgoingConnEx(t, addr, !obfuscatedHeaderFirst)
if c != nil {
if err == nil {
torrent.Add("initiated conn with fallback header obfuscation", 1)
}
//cl.logger.Printf("error establishing fallback connection to %v: %v", addr, err)
return
}
@ -688,9 +687,6 @@ func (cl *Client) outgoingConnection(t *Torrent, addr IpPort, ps peerSource) {
}
return
}
if c == nil {
return
}
defer c.Close()
c.Discovery = ps
cl.runHandshookConn(c, t)
@ -702,9 +698,10 @@ func (cl *Client) incomingPeerPort() int {
return cl.LocalPort()
}
func (cl *Client) initiateHandshakes(c *connection, t *Torrent) (ok bool, err error) {
func (cl *Client) initiateHandshakes(c *connection, t *Torrent) error {
if c.headerEncrypted {
var rw io.ReadWriter
var err error
rw, c.cryptoMethod, err = mse.InitiateHandshake(
struct {
io.Reader
@ -716,14 +713,17 @@ func (cl *Client) initiateHandshakes(c *connection, t *Torrent) (ok bool, err er
)
c.setRW(rw)
if err != nil {
return
return xerrors.Errorf("header obfuscation handshake: %w", err)
}
}
ih, ok, err := cl.connBTHandshake(c, &t.infoHash)
if ih != t.infoHash {
ok = false
ih, err := cl.connBtHandshake(c, &t.infoHash)
if err != nil {
return xerrors.Errorf("bittorrent protocol handshake: %w", err)
}
return
if ih != t.infoHash {
return errors.New("bittorrent protocol handshake: peer infohash didn't match")
}
return nil
}
// Calls f with any secret keys.
@ -775,12 +775,9 @@ func (cl *Client) receiveHandshakes(c *connection) (t *Torrent, err error) {
err = errors.New("connection not have required header obfuscation")
return
}
ih, ok, err := cl.connBTHandshake(c, nil)
ih, err := cl.connBtHandshake(c, nil)
if err != nil {
err = fmt.Errorf("error during bt handshake: %s", err)
return
}
if !ok {
err = xerrors.Errorf("during bt handshake: %w", err)
return
}
cl.lock()
@ -789,10 +786,9 @@ func (cl *Client) receiveHandshakes(c *connection) (t *Torrent, err error) {
return
}
// Returns !ok if handshake failed for valid reasons.
func (cl *Client) connBTHandshake(c *connection, ih *metainfo.Hash) (ret metainfo.Hash, ok bool, err error) {
res, ok, err := pp.Handshake(c.rw(), ih, cl.peerID, cl.extensionBytes)
if err != nil || !ok {
func (cl *Client) connBtHandshake(c *connection, ih *metainfo.Hash) (ret metainfo.Hash, err error) {
res, err := pp.Handshake(c.rw(), ih, cl.peerID, cl.extensionBytes)
if err != nil {
return
}
ret = res.Hash

1
go.mod
View File

@ -34,6 +34,7 @@ require (
golang.org/x/net v0.0.0-20190628185345-da137c7871d7
golang.org/x/sys v0.0.0-20190712062909-fae7ac547cb7 // indirect
golang.org/x/time v0.0.0-20190308202827-9d24e82272b4
golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7
)
go 1.13

2
go.sum
View File

@ -189,3 +189,5 @@ golang.org/x/time v0.0.0-20181108054448-85acf8d2951c h1:fqgJT0MGcGpPgpWU7VRdRjuA
golang.org/x/time v0.0.0-20181108054448-85acf8d2951c/go.mod h1:tRJNPiyCQ0inRvYxbN9jk5I+vvW/OXSQhTDSoE431IQ=
golang.org/x/time v0.0.0-20190308202827-9d24e82272b4 h1:SvFZT6jyqRaOeXpc5h/JSfZenJ2O330aBsf7JfSUXmQ=
golang.org/x/time v0.0.0-20190308202827-9d24e82272b4/go.mod h1:tRJNPiyCQ0inRvYxbN9jk5I+vvW/OXSQhTDSoE431IQ=
golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7 h1:9zdDQZ7Thm29KFXgAX/+yaf3eVbP7djjWp/dXAppNCc=
golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=

13
peer_protocol/handshake.go
View File

@ -5,6 +5,8 @@ import (
"fmt"
"io"
"golang.org/x/xerrors"
"github.com/anacrolix/missinggo"
"github.com/anacrolix/torrent/metainfo"
)
@ -75,7 +77,7 @@ type HandshakeResult struct {
func Handshake(
sock io.ReadWriter, ih *metainfo.Hash, peerID [20]byte, extensions PeerExtensionBits,
) (
res HandshakeResult, ok bool, err error,
res HandshakeResult, err error,
) {
// Bytes to be sent to the peer. Should never block the sender.
postCh := make(chan []byte, 4)
@ -86,11 +88,8 @@ func Handshake(
defer func() {
close(postCh) // Done writing.
if !ok {
return
}
if err != nil {
panic(err)
return
}
// Wait until writes complete before returning from handshake.
err = <-writeDone
@ -116,10 +115,11 @@ func Handshake(
var b [68]byte
_, err = io.ReadFull(sock, b[:68])
if err != nil {
err = nil
err = xerrors.Errorf("while reading: %w", err)
return
}
if string(b[:20]) != Protocol {
err = xerrors.Errorf("unexpected protocol string")
return
}
missinggo.CopyExact(&res.PeerExtensionBits, b[20:28])
@ -135,6 +135,5 @@ func Handshake(
post(peerID[:])
}
ok = true
return
}

3
torrent_test.go
View File

@ -183,9 +183,8 @@ func TestTorrentMetainfoIncompleteMetadata(t *testing.T) {
var pex PeerExtensionBits
pex.SetBit(pp.ExtensionBitExtended)
hr, ok, err := pp.Handshake(nc, &ih, [20]byte{}, pex)
hr, err := pp.Handshake(nc, &ih, [20]byte{}, pex)
require.NoError(t, err)
assert.True(t, ok)
assert.True(t, hr.PeerExtensionBits.GetBit(pp.ExtensionBitExtended))
assert.EqualValues(t, cl.PeerID(), hr.PeerID)
assert.EqualValues(t, ih, hr.Hash)