package torrent import ( "context" "fmt" "net" "net/url" "strconv" "github.com/anacrolix/missinggo" "github.com/anacrolix/missinggo/perf" "github.com/pkg/errors" "golang.org/x/net/proxy" ) type dialer interface { dial(_ context.Context, addr string) (net.Conn, error) } type socket interface { net.Listener dialer } func getProxyDialer(proxyURL string) (proxy.Dialer, error) { fixedURL, err := url.Parse(proxyURL) if err != nil { return nil, err } return proxy.FromURL(fixedURL, proxy.Direct) } func listen(n network, addr, proxyURL string, f firewallCallback) (socket, error) { switch { case n.Tcp: return listenTcp(n.String(), addr, proxyURL) case n.Udp: return listenUtp(n.String(), addr, proxyURL, f) default: panic(n) } } func listenTcp(network, address, proxyURL string) (s socket, err error) { l, err := net.Listen(network, address) if err != nil { return } defer func() { if err != nil { l.Close() } }() // If we don't need the proxy - then we should return default net.Dialer, // otherwise, let's try to parse the proxyURL and return proxy.Dialer if len(proxyURL) != 0 { dl := disabledListener{l} dialer, err := getProxyDialer(proxyURL) if err != nil { return nil, err } return tcpSocket{dl, func(ctx context.Context, addr string) (conn net.Conn, err error) { defer perf.ScopeTimerErr(&err)() return dialer.Dial(network, addr) }}, nil } dialer := net.Dialer{} return tcpSocket{l, func(ctx context.Context, addr string) (conn net.Conn, err error) { defer perf.ScopeTimerErr(&err)() return dialer.DialContext(ctx, network, addr) }}, nil } type disabledListener struct { net.Listener } func (dl disabledListener) Accept() (net.Conn, error) { return nil, fmt.Errorf("tcp listener disabled due to proxy") } type tcpSocket struct { net.Listener d func(ctx context.Context, addr string) (net.Conn, error) } func (me tcpSocket) dial(ctx context.Context, addr string) (net.Conn, error) { return me.d(ctx, addr) } func listenAll(networks []network, getHost func(string) string, port int, proxyURL string, f firewallCallback) ([]socket, error) { if len(networks) == 0 { return nil, nil } var nahs []networkAndHost for _, n := range networks { nahs = append(nahs, networkAndHost{n, getHost(n.String())}) } for { ss, retry, err := listenAllRetry(nahs, port, proxyURL, f) if !retry { return ss, err } } } type networkAndHost struct { Network network Host string } func listenAllRetry(nahs []networkAndHost, port int, proxyURL string, f firewallCallback) (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), proxyURL, f) if err != nil { return nil, false, errors.Wrap(err, "first listen") } defer func() { if err != nil || retry { for _, s := range ss { s.Close() } ss = nil } }() 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), proxyURL, f) if err != nil { return ss, missinggo.IsAddrInUse(err) && port == 0, errors.Wrap(err, "subsequent listen") } ss = append(ss, s) } return } type firewallCallback func(net.Addr) bool func listenUtp(network, addr, proxyURL string, fc firewallCallback) (s socket, err error) { us, err := NewUtpSocket(network, addr, fc) if err != nil { return } // If we don't need the proxy - then we should return default net.Dialer, // otherwise, let's try to parse the proxyURL and return proxy.Dialer if len(proxyURL) != 0 { ds := disabledUtpSocket{us} dialer, err := getProxyDialer(proxyURL) if err != nil { return nil, err } return utpSocketSocket{ds, network, dialer}, nil } return utpSocketSocket{us, network, nil}, nil } type disabledUtpSocket struct { utpSocket } func (ds disabledUtpSocket) Accept() (net.Conn, error) { return nil, fmt.Errorf("utp listener disabled due to proxy") } type utpSocketSocket struct { utpSocket network string d proxy.Dialer } func (me utpSocketSocket) dial(ctx context.Context, addr string) (conn net.Conn, err error) { defer perf.ScopeTimerErr(&err)() if me.d != nil { return me.d.Dial(me.network, addr) } return me.utpSocket.DialContext(ctx, me.network, addr) }