package core import ( "errors" "golang.org/x/net/context" "log" "net" "strings" "time" ) // XXX on failures, decide how long to wait before trying again // XXX limit and queue global attempts? // XXX circ/stream/fetch monitoring type OnionConnector struct { Network *Network NeverGiveUp bool AttemptCount int } // Attempt to connect to 'address', which must be a .onion address and port, // using the Network from this OnionConnector instance. // // If NeverGiveUp is set, failed connections will be retried automatically, // with appropriate backoff periods, and an error is only returned in fatal // situations. The backoff is defined by AttemptCount on the OnionConnector // instance -- it is not reset after Connect returns. // // If the Network is not ready, this function will wait and monitor the // Network's status. // // Context can be used to set a timeout, deadline, or cancel function for // the connection attempt. func (oc *OnionConnector) Connect(address string, c context.Context) (net.Conn, error) { if oc.Network == nil { return nil, errors.New("No network configured for connector") } host, _, err := net.SplitHostPort(address) if err != nil || !strings.HasSuffix(host, ".onion") { return nil, errors.New("Invalid address") } options := &net.Dialer{ Cancel: c.Done(), Timeout: 0, // XXX should use timeout } for { // XXX This waits to know SOCKS info, but does not wait for connection // ready state; should it? proxy, err := oc.Network.WaitForProxyDialer(options, c) if err != nil { return nil, err } conn, err := proxy.Dial("tcp", address) if err != nil { if c.Err() != nil { return nil, c.Err() } if !oc.NeverGiveUp { return nil, err } log.Printf("Connection attempt to %s failed: %s", address, err) if err := oc.Backoff(c); err != nil { return nil, err } continue } return conn, nil } } func (oc *OnionConnector) Backoff(c context.Context) error { oc.AttemptCount++ // XXX This should actually do backoff and be less dumb waitCtx, finish := context.WithTimeout(c, 10*time.Second) defer finish() <-waitCtx.Done() return c.Err() }