"context"
"net"
"strconv"
+ "syscall"
+ "github.com/anacrolix/log"
"github.com/anacrolix/missinggo/perf"
"github.com/anacrolix/missinggo/v2"
"github.com/pkg/errors"
Close() error
}
-func listen(n network, addr string, f firewallCallback) (socket, error) {
+func listen(n network, addr string, f firewallCallback, logger log.Logger) (socket, error) {
switch {
case n.Tcp:
return listenTcp(n.String(), addr)
case n.Udp:
- return listenUtp(n.String(), addr, f)
+ return listenUtp(n.String(), addr, f, logger)
default:
panic(n)
}
}
+// Dialing TCP from a local port limits us to a single outgoing TCP connection to each remote
+// client. Instead, this should be a last resort if we need to use holepunching, and only then to
+// connect to other clients that actually try to holepunch TCP.
+const dialTcpFromListenPort = false
+
+var tcpListenConfig = net.ListenConfig{
+ Control: func(network, address string, c syscall.RawConn) (err error) {
+ controlErr := c.Control(func(fd uintptr) {
+ if dialTcpFromListenPort {
+ err = setReusePortSockOpts(fd)
+ }
+ })
+ if err != nil {
+ return
+ }
+ err = controlErr
+ return
+ },
+ // BitTorrent connections manage their own keep-alives.
+ KeepAlive: -1,
+}
+
func listenTcp(network, address string) (s socket, err error) {
- l, err := net.Listen(network, address)
- return tcpSocket{
+ l, err := tcpListenConfig.Listen(context.Background(), network, address)
+ if err != nil {
+ return
+ }
+ netDialer := net.Dialer{
+ // We don't want fallback, as we explicitly manage the IPv4/IPv6 distinction ourselves,
+ // although it's probably not triggered as I think the network is already constrained to
+ // tcp4 or tcp6 at this point.
+ FallbackDelay: -1,
+ // BitTorrent connections manage their own keepalives.
+ KeepAlive: tcpListenConfig.KeepAlive,
+ Control: func(network, address string, c syscall.RawConn) (err error) {
+ controlErr := c.Control(func(fd uintptr) {
+ err = setSockNoLinger(fd)
+ if err != nil {
+ // Failing to disable linger is undesirable, but not fatal.
+ log.Levelf(log.Debug, "error setting linger socket option on tcp socket: %v", err)
+ err = nil
+ }
+ // This is no longer required I think, see
+ // https://github.com/anacrolix/torrent/discussions/856. I added this originally to
+ // allow dialling out from the client's listen port, but that doesn't really work. I
+ // think Linux older than ~2013 doesn't support SO_REUSEPORT.
+ if dialTcpFromListenPort {
+ err = setReusePortSockOpts(fd)
+ }
+ })
+ if err == nil {
+ err = controlErr
+ }
+ return
+ },
+ }
+ if dialTcpFromListenPort {
+ netDialer.LocalAddr = l.Addr()
+ }
+ s = tcpSocket{
Listener: l,
NetworkDialer: NetworkDialer{
Network: network,
- Dialer: DefaultNetDialer,
+ Dialer: &netDialer,
},
- }, err
+ }
+ return
}
type tcpSocket struct {
NetworkDialer
}
-func listenAll(networks []network, getHost func(string) string, port int, f firewallCallback) ([]socket, error) {
+func listenAll(networks []network, getHost func(string) string, port int, f firewallCallback, logger log.Logger) ([]socket, error) {
if len(networks) == 0 {
return nil, nil
}
nahs = append(nahs, networkAndHost{n, getHost(n.String())})
}
for {
- ss, retry, err := listenAllRetry(nahs, port, f)
+ ss, retry, err := listenAllRetry(nahs, port, f, logger)
if !retry {
return ss, err
}
Host string
}
-func listenAllRetry(nahs []networkAndHost, port int, f firewallCallback) (ss []socket, retry bool, err error) {
+func listenAllRetry(nahs []networkAndHost, port int, f firewallCallback, logger log.Logger) (ss []socket, retry bool, err error) {
ss = make([]socket, 1, len(nahs))
portStr := strconv.FormatInt(int64(port), 10)
- ss[0], err = listen(nahs[0].Network, net.JoinHostPort(nahs[0].Host, portStr), f)
+ ss[0], err = listen(nahs[0].Network, net.JoinHostPort(nahs[0].Host, portStr), f, logger)
if err != nil {
return nil, false, errors.Wrap(err, "first listen")
}
}()
portStr = strconv.FormatInt(int64(missinggo.AddrPort(ss[0].Addr())), 10)
for _, nah := range nahs[1:] {
- s, err := listen(nah.Network, net.JoinHostPort(nah.Host, portStr), f)
+ s, err := listen(nah.Network, net.JoinHostPort(nah.Host, portStr), f, logger)
if err != nil {
return ss,
missinggo.IsAddrInUse(err) && port == 0,
return
}
+// This isn't aliased from go-libutp since that assumes CGO.
type firewallCallback func(net.Addr) bool
-func listenUtp(network, addr string, fc firewallCallback) (socket, error) {
- us, err := NewUtpSocket(network, addr, fc)
+func listenUtp(network, addr string, fc firewallCallback, logger log.Logger) (socket, error) {
+ us, err := NewUtpSocket(network, addr, fc, logger)
return utpSocketSocket{us, network}, err
}