9 "github.com/anacrolix/log"
10 "github.com/anacrolix/missinggo/perf"
11 "github.com/anacrolix/missinggo/v2"
12 "github.com/pkg/errors"
15 type Listener interface {
16 // Accept waits for and returns the next connection to the listener.
17 Accept() (net.Conn, error)
19 // Addr returns the listener's network address.
23 type socket interface {
29 func listen(n network, addr string, f firewallCallback, logger log.Logger) (socket, error) {
32 return listenTcp(n.String(), addr)
34 return listenUtp(n.String(), addr, f, logger)
40 var tcpListenConfig = net.ListenConfig{
41 Control: func(network, address string, c syscall.RawConn) (err error) {
42 controlErr := c.Control(func(fd uintptr) {
43 err = setReusePortSockOpts(fd)
51 // BitTorrent connections manage their own keep-alives.
55 func listenTcp(network, address string) (s socket, err error) {
56 l, err := tcpListenConfig.Listen(context.Background(), network, address)
59 NetworkDialer: NetworkDialer{
62 // My hope is that dialling out from a consistent port will improve the
63 // hole-punching behaviour. It might also prevent duplicate connections to the same
64 // peer if the peer does the same thing. There should probably be a fallback dialer
65 // if we fail to configure the socket to reuse ports for whatever reason.
67 // We don't want fallback, as we explicitly manage the IPv4/IPv6 distinction
68 // ourselves, although it's probably not triggered as I think the network is already
69 // constrained to tcp4 or tcp6 at this point.
71 // BitTorrent connections manage their own keep-alives.
72 KeepAlive: tcpListenConfig.KeepAlive,
73 Control: func(network, address string, c syscall.RawConn) (err error) {
74 controlErr := c.Control(func(fd uintptr) {
75 err = setSockNoLinger(fd)
77 // Failing to disable linger is undesirable, but not fatal.
78 log.Printf("error setting linger socket option on tcp socket: %v", err)
80 err = setReusePortSockOpts(fd)
92 type tcpSocket struct {
97 func listenAll(networks []network, getHost func(string) string, port int, f firewallCallback, logger log.Logger) ([]socket, error) {
98 if len(networks) == 0 {
101 var nahs []networkAndHost
102 for _, n := range networks {
103 nahs = append(nahs, networkAndHost{n, getHost(n.String())})
106 ss, retry, err := listenAllRetry(nahs, port, f, logger)
113 type networkAndHost struct {
118 func listenAllRetry(nahs []networkAndHost, port int, f firewallCallback, logger log.Logger) (ss []socket, retry bool, err error) {
119 ss = make([]socket, 1, len(nahs))
120 portStr := strconv.FormatInt(int64(port), 10)
121 ss[0], err = listen(nahs[0].Network, net.JoinHostPort(nahs[0].Host, portStr), f, logger)
123 return nil, false, errors.Wrap(err, "first listen")
126 if err != nil || retry {
127 for _, s := range ss {
133 portStr = strconv.FormatInt(int64(missinggo.AddrPort(ss[0].Addr())), 10)
134 for _, nah := range nahs[1:] {
135 s, err := listen(nah.Network, net.JoinHostPort(nah.Host, portStr), f, logger)
138 missinggo.IsAddrInUse(err) && port == 0,
139 errors.Wrap(err, "subsequent listen")
146 // This isn't aliased from go-libutp since that assumes CGO.
147 type firewallCallback func(net.Addr) bool
149 func listenUtp(network, addr string, fc firewallCallback, logger log.Logger) (socket, error) {
150 us, err := NewUtpSocket(network, addr, fc, logger)
151 return utpSocketSocket{us, network}, err
154 // utpSocket wrapper, additionally wrapped for the torrent package's socket interface.
155 type utpSocketSocket struct {
160 func (me utpSocketSocket) DialerNetwork() string {
164 func (me utpSocketSocket) Dial(ctx context.Context, addr string) (conn net.Conn, err error) {
165 defer perf.ScopeTimerErr(&err)()
166 return me.utpSocket.DialContext(ctx, me.network, addr)