package torrent import ( "bufio" "context" "crypto/rand" "crypto/sha1" "encoding/binary" "errors" "expvar" "fmt" "io" "math" "net" "net/http" "net/netip" "sort" "strconv" "strings" "time" "github.com/anacrolix/chansync/events" "github.com/anacrolix/dht/v2" "github.com/anacrolix/dht/v2/krpc" "github.com/anacrolix/log" "github.com/anacrolix/missinggo/perf" "github.com/anacrolix/missinggo/pubsub" "github.com/anacrolix/missinggo/v2" "github.com/anacrolix/missinggo/v2/bitmap" "github.com/anacrolix/missinggo/v2/pproffd" "github.com/anacrolix/sync" "github.com/anacrolix/torrent/generics" "github.com/anacrolix/torrent/option" request_strategy "github.com/anacrolix/torrent/request-strategy" "github.com/davecgh/go-spew/spew" "github.com/dustin/go-humanize" "github.com/google/btree" "github.com/pion/datachannel" "golang.org/x/time/rate" "github.com/anacrolix/chansync" "github.com/anacrolix/torrent/bencode" "github.com/anacrolix/torrent/internal/limiter" "github.com/anacrolix/torrent/iplist" "github.com/anacrolix/torrent/metainfo" "github.com/anacrolix/torrent/mse" pp "github.com/anacrolix/torrent/peer_protocol" "github.com/anacrolix/torrent/storage" "github.com/anacrolix/torrent/tracker" "github.com/anacrolix/torrent/webtorrent" ) // Clients contain zero or more Torrents. A Client manages a blocklist, the // TCP/UDP protocol ports, and DHT as desired. type Client struct { // An aggregate of stats over all connections. First in struct to ensure 64-bit alignment of // fields. See #262. stats ConnStats _mu lockWithDeferreds event sync.Cond closed chansync.SetOnce config *ClientConfig logger log.Logger peerID PeerID defaultStorage *storage.Client onClose []func() dialers []Dialer listeners []Listener dhtServers []DhtServer ipBlockList iplist.Ranger // Set of addresses that have our client ID. This intentionally will // include ourselves if we end up trying to connect to our own address // through legitimate channels. dopplegangerAddrs map[string]struct{} badPeerIPs map[netip.Addr]struct{} torrents map[InfoHash]*Torrent pieceRequestOrder map[interface{}]*request_strategy.PieceRequestOrder acceptLimiter map[ipStr]int dialRateLimiter *rate.Limiter numHalfOpen int websocketTrackers websocketTrackers activeAnnounceLimiter limiter.Instance webseedHttpClient *http.Client } type ipStr string func (cl *Client) BadPeerIPs() (ips []string) { cl.rLock() ips = cl.badPeerIPsLocked() cl.rUnlock() return } func (cl *Client) badPeerIPsLocked() (ips []string) { ips = make([]string, len(cl.badPeerIPs)) i := 0 for k := range cl.badPeerIPs { ips[i] = k.String() i += 1 } return } func (cl *Client) PeerID() PeerID { return cl.peerID } // Returns the port number for the first listener that has one. No longer assumes that all port // numbers are the same, due to support for custom listeners. Returns zero if no port number is // found. func (cl *Client) LocalPort() (port int) { for i := 0; i < len(cl.listeners); i += 1 { if port = addrPortOrZero(cl.listeners[i].Addr()); port != 0 { return } } return } func writeDhtServerStatus(w io.Writer, s DhtServer) { dhtStats := s.Stats() fmt.Fprintf(w, " ID: %x\n", s.ID()) spew.Fdump(w, dhtStats) } // Writes out a human readable status of the client, such as for writing to a // HTTP status page. func (cl *Client) WriteStatus(_w io.Writer) { cl.rLock() defer cl.rUnlock() w := bufio.NewWriter(_w) defer w.Flush() fmt.Fprintf(w, "Listen port: %d\n", cl.LocalPort()) fmt.Fprintf(w, "Peer ID: %+q\n", cl.PeerID()) fmt.Fprintf(w, "Extension bits: %v\n", cl.config.Extensions) fmt.Fprintf(w, "Announce key: %x\n", cl.announceKey()) fmt.Fprintf(w, "Banned IPs: %d\n", len(cl.badPeerIPsLocked())) cl.eachDhtServer(func(s DhtServer) { fmt.Fprintf(w, "%s DHT server at %s:\n", s.Addr().Network(), s.Addr().String()) writeDhtServerStatus(w, s) }) spew.Fdump(w, &cl.stats) torrentsSlice := cl.torrentsAsSlice() fmt.Fprintf(w, "# Torrents: %d\n", len(torrentsSlice)) fmt.Fprintln(w) sort.Slice(torrentsSlice, func(l, r int) bool { return torrentsSlice[l].infoHash.AsString() < torrentsSlice[r].infoHash.AsString() }) for _, t := range torrentsSlice { if t.name() == "" { fmt.Fprint(w, "") } else { fmt.Fprint(w, t.name()) } fmt.Fprint(w, "\n") if t.info != nil { fmt.Fprintf( w, "%f%% of %d bytes (%s)", 100*(1-float64(t.bytesMissingLocked())/float64(t.info.TotalLength())), *t.length, humanize.Bytes(uint64(*t.length))) } else { w.WriteString("") } fmt.Fprint(w, "\n") t.writeStatus(w) fmt.Fprintln(w) } } // Filters things that are less than warning from UPnP discovery. func upnpDiscoverLogFilter(m log.Msg) bool { level, ok := m.GetLevel() return !m.HasValue(UpnpDiscoverLogTag) || (!level.LessThan(log.Warning) && ok) } func (cl *Client) initLogger() { logger := cl.config.Logger if logger.IsZero() { logger = log.Default if !cl.config.Debug { logger = logger.FilterLevel(log.Info).WithFilter(upnpDiscoverLogFilter) } } cl.logger = logger.WithValues(cl) } func (cl *Client) announceKey() int32 { return int32(binary.BigEndian.Uint32(cl.peerID[16:20])) } // Initializes a bare minimum Client. *Client and *ClientConfig must not be nil. func (cl *Client) init(cfg *ClientConfig) { cl.config = cfg generics.MakeMap(&cl.dopplegangerAddrs) cl.torrents = make(map[metainfo.Hash]*Torrent) cl.dialRateLimiter = rate.NewLimiter(10, 10) cl.activeAnnounceLimiter.SlotsPerKey = 2 cl.event.L = cl.locker() cl.ipBlockList = cfg.IPBlocklist cl.webseedHttpClient = &http.Client{ Transport: &http.Transport{ Proxy: cfg.HTTPProxy, MaxConnsPerHost: 10, }, } } func NewClient(cfg *ClientConfig) (cl *Client, err error) { if cfg == nil { cfg = NewDefaultClientConfig() cfg.ListenPort = 0 } var client Client client.init(cfg) cl = &client go cl.acceptLimitClearer() cl.initLogger() defer func() { if err != nil { cl.Close() cl = nil } }() storageImpl := cfg.DefaultStorage if storageImpl == nil { // We'd use mmap by default but HFS+ doesn't support sparse files. storageImplCloser := storage.NewFile(cfg.DataDir) cl.onClose = append(cl.onClose, func() { if err := storageImplCloser.Close(); err != nil { cl.logger.Printf("error closing default storage: %s", err) } }) storageImpl = storageImplCloser } cl.defaultStorage = storage.NewClient(storageImpl) if cfg.PeerID != "" { missinggo.CopyExact(&cl.peerID, cfg.PeerID) } else { o := copy(cl.peerID[:], cfg.Bep20) _, err = rand.Read(cl.peerID[o:]) if err != nil { panic("error generating peer id") } } sockets, err := listenAll(cl.listenNetworks(), cl.config.ListenHost, cl.config.ListenPort, cl.firewallCallback) if err != nil { return } // Check for panics. cl.LocalPort() for _, _s := range sockets { s := _s // Go is fucking retarded. cl.onClose = append(cl.onClose, func() { go s.Close() }) if peerNetworkEnabled(parseNetworkString(s.Addr().Network()), cl.config) { cl.dialers = append(cl.dialers, s) cl.listeners = append(cl.listeners, s) if cl.config.AcceptPeerConnections { go cl.acceptConnections(s) } } } go cl.forwardPort() if !cfg.NoDHT { for _, s := range sockets { if pc, ok := s.(net.PacketConn); ok { ds, err := cl.NewAnacrolixDhtServer(pc) if err != nil { panic(err) } cl.dhtServers = append(cl.dhtServers, AnacrolixDhtServerWrapper{ds}) cl.onClose = append(cl.onClose, func() { ds.Close() }) } } } cl.websocketTrackers = websocketTrackers{ PeerId: cl.peerID, Logger: cl.logger, GetAnnounceRequest: func(event tracker.AnnounceEvent, infoHash [20]byte) (tracker.AnnounceRequest, error) { cl.lock() defer cl.unlock() t, ok := cl.torrents[infoHash] if !ok { return tracker.AnnounceRequest{}, errors.New("torrent not tracked by client") } return t.announceRequest(event), nil }, Proxy: cl.config.HTTPProxy, OnConn: func(dc datachannel.ReadWriteCloser, dcc webtorrent.DataChannelContext) { cl.lock() defer cl.unlock() t, ok := cl.torrents[dcc.InfoHash] if !ok { cl.logger.WithDefaultLevel(log.Warning).Printf( "got webrtc conn for unloaded torrent with infohash %x", dcc.InfoHash, ) dc.Close() return } go t.onWebRtcConn(dc, dcc) }, } return } func (cl *Client) AddDhtServer(d DhtServer) { cl.dhtServers = append(cl.dhtServers, d) } // Adds a Dialer for outgoing connections. All Dialers are used when attempting to connect to a // given address for any Torrent. func (cl *Client) AddDialer(d Dialer) { cl.lock() defer cl.unlock() cl.dialers = append(cl.dialers, d) for _, t := range cl.torrents { t.openNewConns() } } func (cl *Client) Listeners() []Listener { return cl.listeners } // Registers a Listener, and starts Accepting on it. You must Close Listeners provided this way // yourself. func (cl *Client) AddListener(l Listener) { cl.listeners = append(cl.listeners, l) if cl.config.AcceptPeerConnections { go cl.acceptConnections(l) } } func (cl *Client) firewallCallback(net.Addr) bool { cl.rLock() block := !cl.wantConns() || !cl.config.AcceptPeerConnections cl.rUnlock() if block { torrent.Add("connections firewalled", 1) } else { torrent.Add("connections not firewalled", 1) } return block } func (cl *Client) listenOnNetwork(n network) bool { if n.Ipv4 && cl.config.DisableIPv4 { return false } if n.Ipv6 && cl.config.DisableIPv6 { return false } if n.Tcp && cl.config.DisableTCP { return false } if n.Udp && cl.config.DisableUTP && cl.config.NoDHT { return false } return true } func (cl *Client) listenNetworks() (ns []network) { for _, n := range allPeerNetworks { if cl.listenOnNetwork(n) { ns = append(ns, n) } } return } // Creates an anacrolix/dht Server, as would be done internally in NewClient, for the given conn. func (cl *Client) NewAnacrolixDhtServer(conn net.PacketConn) (s *dht.Server, err error) { cfg := dht.ServerConfig{ IPBlocklist: cl.ipBlockList, Conn: conn, OnAnnouncePeer: cl.onDHTAnnouncePeer, PublicIP: func() net.IP { if connIsIpv6(conn) && cl.config.PublicIp6 != nil { return cl.config.PublicIp6 } return cl.config.PublicIp4 }(), StartingNodes: cl.config.DhtStartingNodes(conn.LocalAddr().Network()), OnQuery: cl.config.DHTOnQuery, Logger: cl.logger.WithContextText(fmt.Sprintf("dht server on %v", conn.LocalAddr().String())), } if f := cl.config.ConfigureAnacrolixDhtServer; f != nil { f(&cfg) } s, err = dht.NewServer(&cfg) if err == nil { go func() { ts, err := s.Bootstrap() if err != nil { cl.logger.Printf("error bootstrapping dht: %s", err) } log.Fstr("%v completed bootstrap (%+v)", s, ts).AddValues(s, ts).Log(cl.logger) }() } return } func (cl *Client) Closed() events.Done { return cl.closed.Done() } func (cl *Client) eachDhtServer(f func(DhtServer)) { for _, ds := range cl.dhtServers { f(ds) } } // Stops the client. All connections to peers are closed and all activity will come to a halt. func (cl *Client) Close() (errs []error) { var closeGroup sync.WaitGroup // For concurrent cleanup to complete before returning cl.lock() for _, t := range cl.torrents { err := t.close(&closeGroup) if err != nil { errs = append(errs, err) } } for i := range cl.onClose { cl.onClose[len(cl.onClose)-1-i]() } cl.closed.Set() cl.unlock() cl.event.Broadcast() closeGroup.Wait() // defer is LIFO. We want to Wait() after cl.unlock() return } func (cl *Client) ipBlockRange(ip net.IP) (r iplist.Range, blocked bool) { if cl.ipBlockList == nil { return } return cl.ipBlockList.Lookup(ip) } func (cl *Client) ipIsBlocked(ip net.IP) bool { _, blocked := cl.ipBlockRange(ip) return blocked } func (cl *Client) wantConns() bool { if cl.config.AlwaysWantConns { return true } for _, t := range cl.torrents { if t.wantConns() { return true } } return false } // TODO: Apply filters for non-standard networks, particularly rate-limiting. func (cl *Client) rejectAccepted(conn net.Conn) error { if !cl.wantConns() { return errors.New("don't want conns right now") } ra := conn.RemoteAddr() if rip := addrIpOrNil(ra); rip != nil { if cl.config.DisableIPv4Peers && rip.To4() != nil { return errors.New("ipv4 peers disabled") } if cl.config.DisableIPv4 && len(rip) == net.IPv4len { return errors.New("ipv4 disabled") } if cl.config.DisableIPv6 && len(rip) == net.IPv6len && rip.To4() == nil { return errors.New("ipv6 disabled") } if cl.rateLimitAccept(rip) { return errors.New("source IP accepted rate limited") } if cl.badPeerIPPort(rip, missinggo.AddrPort(ra)) { return errors.New("bad source addr") } } return nil } func (cl *Client) acceptConnections(l Listener) { for { conn, err := l.Accept() torrent.Add("client listener accepts", 1) conn = pproffd.WrapNetConn(conn) cl.rLock() closed := cl.closed.IsSet() var reject error if !closed && conn != nil { reject = cl.rejectAccepted(conn) } cl.rUnlock() if closed { if conn != nil { conn.Close() } return } if err != nil { log.Fmsg("error accepting connection: %s", err).SetLevel(log.Debug).Log(cl.logger) continue } go func() { if reject != nil { torrent.Add("rejected accepted connections", 1) log.Fmsg("rejecting accepted conn: %v", reject).SetLevel(log.Debug).Log(cl.logger) conn.Close() } else { go cl.incomingConnection(conn) } log.Fmsg("accepted %q connection at %q from %q", l.Addr().Network(), conn.LocalAddr(), conn.RemoteAddr(), ).SetLevel(log.Debug).Log(cl.logger) torrent.Add(fmt.Sprintf("accepted conn remote IP len=%d", len(addrIpOrNil(conn.RemoteAddr()))), 1) torrent.Add(fmt.Sprintf("accepted conn network=%s", conn.RemoteAddr().Network()), 1) torrent.Add(fmt.Sprintf("accepted on %s listener", l.Addr().Network()), 1) }() } } // Creates the PeerConn.connString for a regular net.Conn PeerConn. func regularNetConnPeerConnConnString(nc net.Conn) string { return fmt.Sprintf("%s-%s", nc.LocalAddr(), nc.RemoteAddr()) } func (cl *Client) incomingConnection(nc net.Conn) { defer nc.Close() if tc, ok := nc.(*net.TCPConn); ok { tc.SetLinger(0) } c := cl.newConnection(nc, false, nc.RemoteAddr(), nc.RemoteAddr().Network(), regularNetConnPeerConnConnString(nc)) defer func() { cl.lock() defer cl.unlock() c.close() }() c.Discovery = PeerSourceIncoming cl.runReceivedConn(c) } // Returns a handle to the given torrent, if it's present in the client. func (cl *Client) Torrent(ih metainfo.Hash) (t *Torrent, ok bool) { cl.lock() defer cl.unlock() t, ok = cl.torrents[ih] return } func (cl *Client) torrent(ih metainfo.Hash) *Torrent { return cl.torrents[ih] } type DialResult struct { Conn net.Conn Dialer Dialer } func countDialResult(err error) { if err == nil { torrent.Add("successful dials", 1) } else { torrent.Add("unsuccessful dials", 1) } } func reducedDialTimeout(minDialTimeout, max time.Duration, halfOpenLimit, pendingPeers int) (ret time.Duration) { ret = max / time.Duration((pendingPeers+halfOpenLimit)/halfOpenLimit) if ret < minDialTimeout { ret = minDialTimeout } return } // Returns whether an address is known to connect to a client with our own ID. func (cl *Client) dopplegangerAddr(addr string) bool { _, ok := cl.dopplegangerAddrs[addr] return ok } // Returns a connection over UTP or TCP, whichever is first to connect. func (cl *Client) dialFirst(ctx context.Context, addr string) (res DialResult) { return DialFirst(ctx, addr, cl.dialers) } // Returns a connection over UTP or TCP, whichever is first to connect. func DialFirst(ctx context.Context, addr string, dialers []Dialer) (res DialResult) { { t := perf.NewTimer(perf.CallerName(0)) defer func() { if res.Conn == nil { t.Mark(fmt.Sprintf("returned no conn (context: %v)", ctx.Err())) } else { t.Mark("returned conn over " + res.Dialer.DialerNetwork()) } }() } ctx, cancel := context.WithCancel(ctx) // As soon as we return one connection, cancel the others. defer cancel() left := 0 resCh := make(chan DialResult, left) for _, _s := range dialers { left++ s := _s go func() { resCh <- DialResult{ dialFromSocket(ctx, s, addr), s, } }() } // Wait for a successful connection. func() { defer perf.ScopeTimer()() for ; left > 0 && res.Conn == nil; left-- { res = <-resCh } }() // There are still incompleted dials. go func() { for ; left > 0; left-- { conn := (<-resCh).Conn if conn != nil { conn.Close() } } }() if res.Conn != nil { go torrent.Add(fmt.Sprintf("network dialed first: %s", res.Conn.RemoteAddr().Network()), 1) } return res } func dialFromSocket(ctx context.Context, s Dialer, addr string) net.Conn { c, err := s.Dial(ctx, addr) // This is a bit optimistic, but it looks non-trivial to thread this through the proxy code. Set // it now in case we close the connection forthwith. if tc, ok := c.(*net.TCPConn); ok { tc.SetLinger(0) } countDialResult(err) return c } func forgettableDialError(err error) bool { return strings.Contains(err.Error(), "no suitable address found") } func (cl *Client) noLongerHalfOpen(t *Torrent, addr string) { if _, ok := t.halfOpen[addr]; !ok { panic("invariant broken") } delete(t.halfOpen, addr) cl.numHalfOpen-- for _, t := range cl.torrents { t.openNewConns() } } // Performs initiator handshakes and returns a connection. Returns nil *connection if no connection // for valid reasons. func (cl *Client) initiateProtocolHandshakes( ctx context.Context, nc net.Conn, t *Torrent, outgoing, encryptHeader bool, remoteAddr PeerRemoteAddr, network, connString string, ) ( c *PeerConn, err error, ) { c = cl.newConnection(nc, outgoing, remoteAddr, network, connString) c.headerEncrypted = encryptHeader ctx, cancel := context.WithTimeout(ctx, cl.config.HandshakesTimeout) defer cancel() dl, ok := ctx.Deadline() if !ok { panic(ctx) } err = nc.SetDeadline(dl) if err != nil { panic(err) } 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 PeerRemoteAddr, obfuscatedHeader bool) (*PeerConn, error) { dialCtx, cancel := context.WithTimeout(context.Background(), func() time.Duration { cl.rLock() defer cl.rUnlock() return t.dialTimeout() }()) defer cancel() dr := cl.dialFirst(dialCtx, addr.String()) nc := dr.Conn if nc == nil { if dialCtx.Err() != nil { return nil, fmt.Errorf("dialing: %w", dialCtx.Err()) } return nil, errors.New("dial failed") } c, err := cl.initiateProtocolHandshakes(context.Background(), nc, t, true, obfuscatedHeader, addr, dr.Dialer.DialerNetwork(), regularNetConnPeerConnConnString(nc)) if err != nil { nc.Close() } return c, err } // Returns nil connection and nil error if no connection could be established // for valid reasons. func (cl *Client) establishOutgoingConn(t *Torrent, addr PeerRemoteAddr) (c *PeerConn, err error) { torrent.Add("establish outgoing connection", 1) obfuscatedHeaderFirst := cl.config.HeaderObfuscationPolicy.Preferred c, err = cl.establishOutgoingConnEx(t, addr, obfuscatedHeaderFirst) 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. return } // Try again with encryption if we didn't earlier, or without if we did. c, err = cl.establishOutgoingConnEx(t, addr, !obfuscatedHeaderFirst) 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 } // Called to dial out and run a connection. The addr we're given is already // considered half-open. func (cl *Client) outgoingConnection(t *Torrent, addr PeerRemoteAddr, ps PeerSource, trusted bool) { cl.dialRateLimiter.Wait(context.Background()) c, err := cl.establishOutgoingConn(t, addr) if err == nil { c.conn.SetWriteDeadline(time.Time{}) } cl.lock() defer cl.unlock() // Don't release lock between here and addPeerConn, unless it's for // failure. cl.noLongerHalfOpen(t, addr.String()) if err != nil { if cl.config.Debug { cl.logger.Printf("error establishing outgoing connection to %v: %v", addr, err) } return } defer c.close() c.Discovery = ps c.trusted = trusted t.runHandshookConnLoggingErr(c) } // The port number for incoming peer connections. 0 if the client isn't listening. func (cl *Client) incomingPeerPort() int { return cl.LocalPort() } func (cl *Client) initiateHandshakes(c *PeerConn, t *Torrent) error { if c.headerEncrypted { var rw io.ReadWriter var err error rw, c.cryptoMethod, err = mse.InitiateHandshake( struct { io.Reader io.Writer }{c.r, c.w}, t.infoHash[:], nil, cl.config.CryptoProvides, ) c.setRW(rw) if err != nil { return fmt.Errorf("header obfuscation handshake: %w", err) } } ih, err := cl.connBtHandshake(c, &t.infoHash) if err != nil { return fmt.Errorf("bittorrent protocol handshake: %w", err) } if ih != t.infoHash { return errors.New("bittorrent protocol handshake: peer infohash didn't match") } return nil } // Calls f with any secret keys. Note that it takes the Client lock, and so must be used from code // that won't also try to take the lock. This saves us copying all the infohashes everytime. func (cl *Client) forSkeys(f func([]byte) bool) { cl.rLock() defer cl.rUnlock() if false { // Emulate the bug from #114 var firstIh InfoHash for ih := range cl.torrents { firstIh = ih break } for range cl.torrents { if !f(firstIh[:]) { break } } return } for ih := range cl.torrents { if !f(ih[:]) { break } } } func (cl *Client) handshakeReceiverSecretKeys() mse.SecretKeyIter { if ret := cl.config.Callbacks.ReceiveEncryptedHandshakeSkeys; ret != nil { return ret } return cl.forSkeys } // Do encryption and bittorrent handshakes as receiver. func (cl *Client) receiveHandshakes(c *PeerConn) (t *Torrent, err error) { defer perf.ScopeTimerErr(&err)() var rw io.ReadWriter rw, c.headerEncrypted, c.cryptoMethod, err = handleEncryption(c.rw(), cl.handshakeReceiverSecretKeys(), cl.config.HeaderObfuscationPolicy, cl.config.CryptoSelector) c.setRW(rw) if err == nil || err == mse.ErrNoSecretKeyMatch { if c.headerEncrypted { torrent.Add("handshakes received encrypted", 1) } else { torrent.Add("handshakes received unencrypted", 1) } } else { torrent.Add("handshakes received with error while handling encryption", 1) } if err != nil { if err == mse.ErrNoSecretKeyMatch { err = nil } return } if cl.config.HeaderObfuscationPolicy.RequirePreferred && c.headerEncrypted != cl.config.HeaderObfuscationPolicy.Preferred { err = errors.New("connection does not have required header obfuscation") return } ih, err := cl.connBtHandshake(c, nil) if err != nil { return nil, fmt.Errorf("during bt handshake: %w", err) } cl.lock() t = cl.torrents[ih] cl.unlock() return } var successfulPeerWireProtocolHandshakePeerReservedBytes expvar.Map func init() { torrent.Set( "successful_peer_wire_protocol_handshake_peer_reserved_bytes", &successfulPeerWireProtocolHandshakePeerReservedBytes) } func (cl *Client) connBtHandshake(c *PeerConn, ih *metainfo.Hash) (ret metainfo.Hash, err error) { res, err := pp.Handshake(c.rw(), ih, cl.peerID, cl.config.Extensions) if err != nil { return } successfulPeerWireProtocolHandshakePeerReservedBytes.Add(res.PeerExtensionBits.String(), 1) ret = res.Hash c.PeerExtensionBytes = res.PeerExtensionBits c.PeerID = res.PeerID c.completedHandshake = time.Now() if cb := cl.config.Callbacks.CompletedHandshake; cb != nil { cb(c, res.Hash) } return } func (cl *Client) runReceivedConn(c *PeerConn) { err := c.conn.SetDeadline(time.Now().Add(cl.config.HandshakesTimeout)) if err != nil { panic(err) } t, err := cl.receiveHandshakes(c) if err != nil { log.Fmsg( "error receiving handshakes on %v: %s", c, err, ).SetLevel(log.Debug). Add( "network", c.Network, ).Log(cl.logger) torrent.Add("error receiving handshake", 1) cl.lock() cl.onBadAccept(c.RemoteAddr) cl.unlock() return } if t == nil { torrent.Add("received handshake for unloaded torrent", 1) log.Fmsg("received handshake for unloaded torrent").SetLevel(log.Debug).Log(cl.logger) cl.lock() cl.onBadAccept(c.RemoteAddr) cl.unlock() return } torrent.Add("received handshake for loaded torrent", 1) c.conn.SetWriteDeadline(time.Time{}) cl.lock() defer cl.unlock() t.runHandshookConnLoggingErr(c) } // Client lock must be held before entering this. func (cl *Client) runHandshookConn(c *PeerConn, t *Torrent) error { c.setTorrent(t) for i, b := range cl.config.MinPeerExtensions { if c.PeerExtensionBytes[i]&b != b { return fmt.Errorf("peer did not meet minimum peer extensions: %x", c.PeerExtensionBytes[:]) } } if c.PeerID == cl.peerID { if c.outgoing { connsToSelf.Add(1) addr := c.RemoteAddr.String() cl.dopplegangerAddrs[addr] = struct{}{} } /* else { // Because the remote address is not necessarily the same as its client's torrent listen // address, we won't record the remote address as a doppleganger. Instead, the initiator // can record *us* as the doppleganger. } */ t.logger.WithLevel(log.Debug).Printf("local and remote peer ids are the same") return nil } c.r = deadlineReader{c.conn, c.r} completedHandshakeConnectionFlags.Add(c.connectionFlags(), 1) if connIsIpv6(c.conn) { torrent.Add("completed handshake over ipv6", 1) } if err := t.addPeerConn(c); err != nil { return fmt.Errorf("adding connection: %w", err) } defer t.dropConnection(c) c.startWriter() cl.sendInitialMessages(c, t) c.initUpdateRequestsTimer() err := c.mainReadLoop() if err != nil { return fmt.Errorf("main read loop: %w", err) } return nil } const check = false func (p *Peer) initUpdateRequestsTimer() { if check { if p.updateRequestsTimer != nil { panic(p.updateRequestsTimer) } } p.updateRequestsTimer = time.AfterFunc(math.MaxInt64, p.updateRequestsTimerFunc) } const peerUpdateRequestsTimerReason = "updateRequestsTimer" func (c *Peer) updateRequestsTimerFunc() { c.locker().Lock() defer c.locker().Unlock() if c.closed.IsSet() { return } if c.isLowOnRequests() { // If there are no outstanding requests, then a request update should have already run. return } if d := time.Since(c.lastRequestUpdate); d < updateRequestsTimerDuration { // These should be benign, Timer.Stop doesn't guarantee that its function won't run if it's // already been fired. torrent.Add("spurious timer requests updates", 1) return } c.updateRequests(peerUpdateRequestsTimerReason) } // Maximum pending requests we allow peers to send us. If peer requests are buffered on read, this // instructs the amount of memory that might be used to cache pending writes. Assuming 512KiB // (1<<19) cached for sending, for 16KiB (1<<14) chunks. const localClientReqq = 1 << 5 // See the order given in Transmission's tr_peerMsgsNew. func (cl *Client) sendInitialMessages(conn *PeerConn, torrent *Torrent) { if conn.PeerExtensionBytes.SupportsExtended() && cl.config.Extensions.SupportsExtended() { conn.write(pp.Message{ Type: pp.Extended, ExtendedID: pp.HandshakeExtendedID, ExtendedPayload: func() []byte { msg := pp.ExtendedHandshakeMessage{ M: map[pp.ExtensionName]pp.ExtensionNumber{ pp.ExtensionNameMetadata: metadataExtendedId, }, V: cl.config.ExtendedHandshakeClientVersion, Reqq: localClientReqq, YourIp: pp.CompactIp(conn.remoteIp()), Encryption: cl.config.HeaderObfuscationPolicy.Preferred || !cl.config.HeaderObfuscationPolicy.RequirePreferred, Port: cl.incomingPeerPort(), MetadataSize: torrent.metadataSize(), // TODO: We can figured these out specific to the socket // used. Ipv4: pp.CompactIp(cl.config.PublicIp4.To4()), Ipv6: cl.config.PublicIp6.To16(), } if !cl.config.DisablePEX { msg.M[pp.ExtensionNamePex] = pexExtendedId } return bencode.MustMarshal(msg) }(), }) } func() { if conn.fastEnabled() { if torrent.haveAllPieces() { conn.write(pp.Message{Type: pp.HaveAll}) conn.sentHaves.AddRange(0, bitmap.BitRange(conn.t.NumPieces())) return } else if !torrent.haveAnyPieces() { conn.write(pp.Message{Type: pp.HaveNone}) conn.sentHaves.Clear() return } } conn.postBitfield() }() if conn.PeerExtensionBytes.SupportsDHT() && cl.config.Extensions.SupportsDHT() && cl.haveDhtServer() { conn.write(pp.Message{ Type: pp.Port, Port: cl.dhtPort(), }) } } func (cl *Client) dhtPort() (ret uint16) { if len(cl.dhtServers) == 0 { return } return uint16(missinggo.AddrPort(cl.dhtServers[len(cl.dhtServers)-1].Addr())) } func (cl *Client) haveDhtServer() bool { return len(cl.dhtServers) > 0 } // Process incoming ut_metadata message. func (cl *Client) gotMetadataExtensionMsg(payload []byte, t *Torrent, c *PeerConn) error { var d pp.ExtendedMetadataRequestMsg err := bencode.Unmarshal(payload, &d) if _, ok := err.(bencode.ErrUnusedTrailingBytes); ok { } else if err != nil { return fmt.Errorf("error unmarshalling bencode: %s", err) } piece := d.Piece switch d.Type { case pp.DataMetadataExtensionMsgType: c.allStats(add(1, func(cs *ConnStats) *Count { return &cs.MetadataChunksRead })) if !c.requestedMetadataPiece(piece) { return fmt.Errorf("got unexpected piece %d", piece) } c.metadataRequests[piece] = false begin := len(payload) - d.PieceSize() if begin < 0 || begin >= len(payload) { return fmt.Errorf("data has bad offset in payload: %d", begin) } t.saveMetadataPiece(piece, payload[begin:]) c.lastUsefulChunkReceived = time.Now() err = t.maybeCompleteMetadata() if err != nil { // Log this at the Torrent-level, as we don't partition metadata by Peer yet, so we // don't know who to blame. TODO: Also errors can be returned here that aren't related // to verifying metadata, which should be fixed. This should be tagged with metadata, so // log consumers can filter for this message. t.logger.WithDefaultLevel(log.Warning).Printf("error completing metadata: %v", err) } return err case pp.RequestMetadataExtensionMsgType: if !t.haveMetadataPiece(piece) { c.write(t.newMetadataExtensionMessage(c, pp.RejectMetadataExtensionMsgType, d.Piece, nil)) return nil } start := (1 << 14) * piece c.logger.WithDefaultLevel(log.Debug).Printf("sending metadata piece %d", piece) c.write(t.newMetadataExtensionMessage(c, pp.DataMetadataExtensionMsgType, piece, t.metadataBytes[start:start+t.metadataPieceSize(piece)])) return nil case pp.RejectMetadataExtensionMsgType: return nil default: return errors.New("unknown msg_type value") } } func (cl *Client) badPeerAddr(addr PeerRemoteAddr) bool { if ipa, ok := tryIpPortFromNetAddr(addr); ok { return cl.badPeerIPPort(ipa.IP, ipa.Port) } return false } func (cl *Client) badPeerIPPort(ip net.IP, port int) bool { if port == 0 { return true } if cl.dopplegangerAddr(net.JoinHostPort(ip.String(), strconv.FormatInt(int64(port), 10))) { return true } if _, ok := cl.ipBlockRange(ip); ok { return true } ipAddr, ok := netip.AddrFromSlice(ip) if !ok { panic(ip) } if _, ok := cl.badPeerIPs[ipAddr]; ok { return true } return false } // Return a Torrent ready for insertion into a Client. func (cl *Client) newTorrent(ih metainfo.Hash, specStorage storage.ClientImpl) (t *Torrent) { return cl.newTorrentOpt(AddTorrentOpts{ InfoHash: ih, Storage: specStorage, }) } // Return a Torrent ready for insertion into a Client. func (cl *Client) newTorrentOpt(opts AddTorrentOpts) (t *Torrent) { // use provided storage, if provided storageClient := cl.defaultStorage if opts.Storage != nil { storageClient = storage.NewClient(opts.Storage) } t = &Torrent{ cl: cl, infoHash: opts.InfoHash, peers: prioritizedPeers{ om: btree.New(32), getPrio: func(p PeerInfo) peerPriority { ipPort := p.addr() return bep40PriorityIgnoreError(cl.publicAddr(ipPort.IP), ipPort) }, }, conns: make(map[*PeerConn]struct{}, 2*cl.config.EstablishedConnsPerTorrent), halfOpen: make(map[string]PeerInfo), pieceStateChanges: pubsub.NewPubSub(), storageOpener: storageClient, maxEstablishedConns: cl.config.EstablishedConnsPerTorrent, metadataChanged: sync.Cond{ L: cl.locker(), }, webSeeds: make(map[string]*Peer), gotMetainfoC: make(chan struct{}), } t.smartBanCache.Hash = sha1.Sum t.smartBanCache.Init() t.networkingEnabled.Set() t.logger = cl.logger.WithContextValue(t) if opts.ChunkSize == 0 { opts.ChunkSize = defaultChunkSize } t.setChunkSize(opts.ChunkSize) return } // A file-like handle to some torrent data resource. type Handle interface { io.Reader io.Seeker io.Closer io.ReaderAt } func (cl *Client) AddTorrentInfoHash(infoHash metainfo.Hash) (t *Torrent, new bool) { return cl.AddTorrentInfoHashWithStorage(infoHash, nil) } // Adds a torrent by InfoHash with a custom Storage implementation. // If the torrent already exists then this Storage is ignored and the // existing torrent returned with `new` set to `false` func (cl *Client) AddTorrentInfoHashWithStorage(infoHash metainfo.Hash, specStorage storage.ClientImpl) (t *Torrent, new bool) { cl.lock() defer cl.unlock() t, ok := cl.torrents[infoHash] if ok { return } new = true t = cl.newTorrent(infoHash, specStorage) cl.eachDhtServer(func(s DhtServer) { if cl.config.PeriodicallyAnnounceTorrentsToDht { go t.dhtAnnouncer(s) } }) cl.torrents[infoHash] = t cl.clearAcceptLimits() t.updateWantPeersEvent() // Tickle Client.waitAccept, new torrent may want conns. cl.event.Broadcast() return } // Adds a torrent by InfoHash with a custom Storage implementation. // If the torrent already exists then this Storage is ignored and the // existing torrent returned with `new` set to `false` func (cl *Client) AddTorrentOpt(opts AddTorrentOpts) (t *Torrent, new bool) { infoHash := opts.InfoHash cl.lock() defer cl.unlock() t, ok := cl.torrents[infoHash] if ok { return } new = true t = cl.newTorrentOpt(opts) cl.eachDhtServer(func(s DhtServer) { if cl.config.PeriodicallyAnnounceTorrentsToDht { go t.dhtAnnouncer(s) } }) cl.torrents[infoHash] = t cl.clearAcceptLimits() t.updateWantPeersEvent() // Tickle Client.waitAccept, new torrent may want conns. cl.event.Broadcast() return } type AddTorrentOpts struct { InfoHash InfoHash Storage storage.ClientImpl ChunkSize pp.Integer } // Add or merge a torrent spec. Returns new if the torrent wasn't already in the client. See also // Torrent.MergeSpec. func (cl *Client) AddTorrentSpec(spec *TorrentSpec) (t *Torrent, new bool, err error) { t, new = cl.AddTorrentOpt(AddTorrentOpts{ InfoHash: spec.InfoHash, Storage: spec.Storage, ChunkSize: spec.ChunkSize, }) modSpec := *spec if new { // ChunkSize was already applied by adding a new Torrent, and MergeSpec disallows changing // it. modSpec.ChunkSize = 0 } err = t.MergeSpec(&modSpec) if err != nil && new { t.Drop() } return } type stringAddr string var _ net.Addr = stringAddr("") func (stringAddr) Network() string { return "" } func (me stringAddr) String() string { return string(me) } // The trackers will be merged with the existing ones. If the Info isn't yet known, it will be set. // spec.DisallowDataDownload/Upload will be read and applied // The display name is replaced if the new spec provides one. Note that any `Storage` is ignored. func (t *Torrent) MergeSpec(spec *TorrentSpec) error { if spec.DisplayName != "" { t.SetDisplayName(spec.DisplayName) } t.initialPieceCheckDisabled = spec.DisableInitialPieceCheck if spec.InfoBytes != nil { err := t.SetInfoBytes(spec.InfoBytes) if err != nil { return err } } cl := t.cl cl.AddDhtNodes(spec.DhtNodes) cl.lock() defer cl.unlock() useTorrentSources(spec.Sources, t) for _, url := range spec.Webseeds { t.addWebSeed(url) } for _, peerAddr := range spec.PeerAddrs { t.addPeer(PeerInfo{ Addr: stringAddr(peerAddr), Source: PeerSourceDirect, Trusted: true, }) } if spec.ChunkSize != 0 { panic("chunk size cannot be changed for existing Torrent") } t.addTrackers(spec.Trackers) t.maybeNewConns() t.dataDownloadDisallowed.SetBool(spec.DisallowDataDownload) t.dataUploadDisallowed = spec.DisallowDataUpload return nil } func useTorrentSources(sources []string, t *Torrent) { // TODO: bind context to the lifetime of *Torrent so that it's cancelled if the torrent closes ctx := context.Background() for i := 0; i < len(sources); i += 1 { s := sources[i] go func() { if err := useTorrentSource(ctx, s, t); err != nil { t.logger.WithDefaultLevel(log.Warning).Printf("using torrent source %q: %v", s, err) } else { t.logger.Printf("successfully used source %q", s) } }() } } func useTorrentSource(ctx context.Context, source string, t *Torrent) (err error) { ctx, cancel := context.WithCancel(ctx) defer cancel() go func() { select { case <-t.GotInfo(): case <-t.Closed(): case <-ctx.Done(): } cancel() }() var req *http.Request if req, err = http.NewRequestWithContext(ctx, http.MethodGet, source, nil); err != nil { panic(err) } var resp *http.Response if resp, err = http.DefaultClient.Do(req); err != nil { return } var mi metainfo.MetaInfo err = bencode.NewDecoder(resp.Body).Decode(&mi) resp.Body.Close() if err != nil { if ctx.Err() != nil { return nil } return } return t.MergeSpec(TorrentSpecFromMetaInfo(&mi)) } func (cl *Client) dropTorrent(infoHash metainfo.Hash, wg *sync.WaitGroup) (err error) { t, ok := cl.torrents[infoHash] if !ok { err = fmt.Errorf("no such torrent") return } err = t.close(wg) if err != nil { panic(err) } delete(cl.torrents, infoHash) return } func (cl *Client) allTorrentsCompleted() bool { for _, t := range cl.torrents { if !t.haveInfo() { return false } if !t.haveAllPieces() { return false } } return true } // Returns true when all torrents are completely downloaded and false if the // client is stopped before that. func (cl *Client) WaitAll() bool { cl.lock() defer cl.unlock() for !cl.allTorrentsCompleted() { if cl.closed.IsSet() { return false } cl.event.Wait() } return true } // Returns handles to all the torrents loaded in the Client. func (cl *Client) Torrents() []*Torrent { cl.lock() defer cl.unlock() return cl.torrentsAsSlice() } func (cl *Client) torrentsAsSlice() (ret []*Torrent) { for _, t := range cl.torrents { ret = append(ret, t) } return } func (cl *Client) AddMagnet(uri string) (T *Torrent, err error) { spec, err := TorrentSpecFromMagnetUri(uri) if err != nil { return } T, _, err = cl.AddTorrentSpec(spec) return } func (cl *Client) AddTorrent(mi *metainfo.MetaInfo) (T *Torrent, err error) { ts, err := TorrentSpecFromMetaInfoErr(mi) if err != nil { return } T, _, err = cl.AddTorrentSpec(ts) return } func (cl *Client) AddTorrentFromFile(filename string) (T *Torrent, err error) { mi, err := metainfo.LoadFromFile(filename) if err != nil { return } return cl.AddTorrent(mi) } func (cl *Client) DhtServers() []DhtServer { return cl.dhtServers } func (cl *Client) AddDhtNodes(nodes []string) { for _, n := range nodes { hmp := missinggo.SplitHostMaybePort(n) ip := net.ParseIP(hmp.Host) if ip == nil { cl.logger.Printf("won't add DHT node with bad IP: %q", hmp.Host) continue } ni := krpc.NodeInfo{ Addr: krpc.NodeAddr{ IP: ip, Port: hmp.Port, }, } cl.eachDhtServer(func(s DhtServer) { s.AddNode(ni) }) } } func (cl *Client) banPeerIP(ip net.IP) { generics.MakeMapIfNilAndSet(&cl.badPeerIPs, netip.MustParseAddr(ip.String()), struct{}{}) } func (cl *Client) newConnection(nc net.Conn, outgoing bool, remoteAddr PeerRemoteAddr, network, connString string) (c *PeerConn) { if network == "" { panic(remoteAddr) } c = &PeerConn{ Peer: Peer{ outgoing: outgoing, choking: true, peerChoking: true, PeerMaxRequests: 250, RemoteAddr: remoteAddr, Network: network, callbacks: &cl.config.Callbacks, }, connString: connString, conn: nc, } // TODO: Need to be much more explicit about this, including allowing non-IP bannable addresses. if remoteAddr != nil { netipAddrPort, err := netip.ParseAddrPort(remoteAddr.String()) if err == nil { c.bannableAddr = option.Some(netipAddrPort.Addr()) } } c.peerImpl = c c.logger = cl.logger.WithDefaultLevel(log.Warning).WithContextValue(c) c.setRW(connStatsReadWriter{nc, c}) c.r = &rateLimitedReader{ l: cl.config.DownloadRateLimiter, r: c.r, } c.logger.WithDefaultLevel(log.Debug).Printf("initialized with remote %v over network %v (outgoing=%t)", remoteAddr, network, outgoing) for _, f := range cl.config.Callbacks.NewPeer { f(&c.Peer) } return } func (cl *Client) onDHTAnnouncePeer(ih metainfo.Hash, ip net.IP, port int, portOk bool) { cl.lock() defer cl.unlock() t := cl.torrent(ih) if t == nil { return } t.addPeers([]PeerInfo{{ Addr: ipPortAddr{ip, port}, Source: PeerSourceDhtAnnouncePeer, }}) } func firstNotNil(ips ...net.IP) net.IP { for _, ip := range ips { if ip != nil { return ip } } return nil } func (cl *Client) eachListener(f func(Listener) bool) { for _, s := range cl.listeners { if !f(s) { break } } } func (cl *Client) findListener(f func(Listener) bool) (ret Listener) { for i := 0; i < len(cl.listeners); i += 1 { if ret = cl.listeners[i]; f(ret) { return } } return nil } func (cl *Client) publicIp(peer net.IP) net.IP { // TODO: Use BEP 10 to determine how peers are seeing us. if peer.To4() != nil { return firstNotNil( cl.config.PublicIp4, cl.findListenerIp(func(ip net.IP) bool { return ip.To4() != nil }), ) } return firstNotNil( cl.config.PublicIp6, cl.findListenerIp(func(ip net.IP) bool { return ip.To4() == nil }), ) } func (cl *Client) findListenerIp(f func(net.IP) bool) net.IP { l := cl.findListener( func(l Listener) bool { return f(addrIpOrNil(l.Addr())) }, ) if l == nil { return nil } return addrIpOrNil(l.Addr()) } // Our IP as a peer should see it. func (cl *Client) publicAddr(peer net.IP) IpPort { return IpPort{IP: cl.publicIp(peer), Port: uint16(cl.incomingPeerPort())} } // ListenAddrs addresses currently being listened to. func (cl *Client) ListenAddrs() (ret []net.Addr) { cl.lock() ret = make([]net.Addr, len(cl.listeners)) for i := 0; i < len(cl.listeners); i += 1 { ret[i] = cl.listeners[i].Addr() } cl.unlock() return } func (cl *Client) onBadAccept(addr PeerRemoteAddr) { ipa, ok := tryIpPortFromNetAddr(addr) if !ok { return } ip := maskIpForAcceptLimiting(ipa.IP) if cl.acceptLimiter == nil { cl.acceptLimiter = make(map[ipStr]int) } cl.acceptLimiter[ipStr(ip.String())]++ } func maskIpForAcceptLimiting(ip net.IP) net.IP { if ip4 := ip.To4(); ip4 != nil { return ip4.Mask(net.CIDRMask(24, 32)) } return ip } func (cl *Client) clearAcceptLimits() { cl.acceptLimiter = nil } func (cl *Client) acceptLimitClearer() { for { select { case <-cl.closed.Done(): return case <-time.After(15 * time.Minute): cl.lock() cl.clearAcceptLimits() cl.unlock() } } } func (cl *Client) rateLimitAccept(ip net.IP) bool { if cl.config.DisableAcceptRateLimiting { return false } return cl.acceptLimiter[ipStr(maskIpForAcceptLimiting(ip).String())] > 0 } func (cl *Client) rLock() { cl._mu.RLock() } func (cl *Client) rUnlock() { cl._mu.RUnlock() } func (cl *Client) lock() { cl._mu.Lock() } func (cl *Client) unlock() { cl._mu.Unlock() } func (cl *Client) locker() *lockWithDeferreds { return &cl._mu } func (cl *Client) String() string { return fmt.Sprintf("<%[1]T %[1]p>", cl) } // Returns connection-level aggregate stats at the Client level. See the comment on // TorrentStats.ConnStats. func (cl *Client) ConnStats() ConnStats { return cl.stats.Copy() }