package whisper import ( "fmt" "time" "github.com/ethereum/go-ethereum/common" "github.com/ethereum/go-ethereum/p2p" "github.com/ethereum/go-ethereum/rlp" "gopkg.in/fatih/set.v0" ) // peer represents a whisper protocol peer connection. type peer struct { host *Whisper peer *p2p.Peer ws p2p.MsgReadWriter known *set.Set // Messages already known by the peer to avoid wasting bandwidth quit chan struct{} } // newPeer creates and initializes a new whisper peer connection, returning either // the newly constructed link or a failure reason. func newPeer(host *Whisper, remote *p2p.Peer, rw p2p.MsgReadWriter) (*peer, error) { p := &peer{ host: host, peer: remote, ws: rw, known: set.New(), quit: make(chan struct{}), } if err := p.handshake(); err != nil { return nil, err } return p, nil } // start initiates the peer updater, periodically broadcasting the whisper packets // into the network. func (self *peer) start() { go self.update() self.peer.Debugln("whisper started") } // stop terminates the peer updater, stopping message forwarding to it. func (self *peer) stop() { close(self.quit) self.peer.Debugln("whisper stopped") } // handshake sends the protocol initiation status message to the remote peer and // verifies the remote status too. func (self *peer) handshake() error { // Send the handshake status message asynchronously errc := make(chan error, 1) go func() { errc <- p2p.SendItems(self.ws, statusCode, protocolVersion) }() // Fetch the remote status packet and verify protocol match packet, err := self.ws.ReadMsg() if err != nil { return err } if packet.Code != statusCode { return fmt.Errorf("peer sent %x before status packet", packet.Code) } s := rlp.NewStream(packet.Payload, uint64(packet.Size)) if _, err := s.List(); err != nil { return fmt.Errorf("bad status message: %v", err) } peerVersion, err := s.Uint() if err != nil { return fmt.Errorf("bad status message: %v", err) } if peerVersion != protocolVersion { return fmt.Errorf("protocol version mismatch %d != %d", peerVersion, protocolVersion) } // Wait until out own status is consumed too if err := <-errc; err != nil { return fmt.Errorf("failed to send status packet: %v", err) } return nil } // update executes periodic operations on the peer, including message transmission // and expiration. func (self *peer) update() { // Start the tickers for the updates expire := time.NewTicker(expirationCycle) transmit := time.NewTicker(transmissionCycle) // Loop and transmit until termination is requested for { select { case <-expire.C: self.expire() case <-transmit.C: if err := self.broadcast(); err != nil { self.peer.Infoln("broadcast failed:", err) return } case <-self.quit: return } } } // mark marks an envelope known to the peer so that it won't be sent back. func (self *peer) mark(envelope *Envelope) { self.known.Add(envelope.Hash()) } // marked checks if an envelope is already known to the remote peer. func (self *peer) marked(envelope *Envelope) bool { return self.known.Has(envelope.Hash()) } // expire iterates over all the known envelopes in the host and removes all // expired (unknown) ones from the known list. func (self *peer) expire() { // Assemble the list of available envelopes available := set.NewNonTS() for _, envelope := range self.host.envelopes() { available.Add(envelope.Hash()) } // Cross reference availability with known status unmark := make(map[common.Hash]struct{}) self.known.Each(func(v interface{}) bool { if !available.Has(v.(common.Hash)) { unmark[v.(common.Hash)] = struct{}{} } return true }) // Dump all known but unavailable for hash, _ := range unmark { self.known.Remove(hash) } } // broadcast iterates over the collection of envelopes and transmits yet unknown // ones over the network. func (self *peer) broadcast() error { // Fetch the envelopes and collect the unknown ones envelopes := self.host.envelopes() transmit := make([]*Envelope, 0, len(envelopes)) for _, envelope := range envelopes { if !self.marked(envelope) { transmit = append(transmit, envelope) self.mark(envelope) } } // Transmit the unknown batch (potentially empty) if err := p2p.Send(self.ws, messagesCode, transmit); err != nil { return err } self.peer.DebugDetailln("broadcasted", len(transmit), "message(s)") return nil }