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author | Zsolt Felfoldi <zsfelfoldi@gmail.com> | 2016-10-19 19:04:55 +0800 |
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committer | Felix Lange <fjl@twurst.com> | 2016-11-09 09:12:53 +0800 |
commit | 49da42983af7a775695166689e5bf701bcec4f81 (patch) | |
tree | 2c325a4852695697cc9616a3eac99a432711abdb /p2p/discv5/net.go | |
parent | 7db7109a5b53c339f00e9c05ac826b3dbd1f98e1 (diff) | |
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p2p/discv5: added new topic discovery package
Diffstat (limited to 'p2p/discv5/net.go')
-rw-r--r-- | p2p/discv5/net.go | 1200 |
1 files changed, 1200 insertions, 0 deletions
diff --git a/p2p/discv5/net.go b/p2p/discv5/net.go new file mode 100644 index 000000000..afc92e99f --- /dev/null +++ b/p2p/discv5/net.go @@ -0,0 +1,1200 @@ +// Copyright 2016 The go-ethereum Authors +// This file is part of the go-ethereum library. +// +// The go-ethereum library is free software: you can redistribute it and/or modify +// it under the terms of the GNU Lesser General Public License as published by +// the Free Software Foundation, either version 3 of the License, or +// (at your option) any later version. +// +// The go-ethereum library is distributed in the hope that it will be useful, +// but WITHOUT ANY WARRANTY; without even the implied warranty of +// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +// GNU Lesser General Public License for more details. +// +// You should have received a copy of the GNU Lesser General Public License +// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>. + +package discv5 + +import ( + "bytes" + "crypto/ecdsa" + "errors" + "fmt" + "net" + "time" + + "github.com/ethereum/go-ethereum/common" + "github.com/ethereum/go-ethereum/common/mclock" + "github.com/ethereum/go-ethereum/crypto" + "github.com/ethereum/go-ethereum/crypto/sha3" + "github.com/ethereum/go-ethereum/logger" + "github.com/ethereum/go-ethereum/logger/glog" + "github.com/ethereum/go-ethereum/p2p/nat" + "github.com/ethereum/go-ethereum/rlp" +) + +var ( + errInvalidEvent = errors.New("invalid in current state") + errNoQuery = errors.New("no pending query") + errWrongAddress = errors.New("unknown sender address") +) + +const ( + autoRefreshInterval = 1 * time.Hour + seedCount = 30 + seedMaxAge = 5 * 24 * time.Hour +) + +const testTopic = "foo" + +const ( + printDebugLogs = false + printTestImgLogs = false +) + +func debugLog(s string) { + if printDebugLogs { + fmt.Println(s) + } +} + +// BootNodes are the enode URLs of the P2P bootstrap nodes for the experimental RLPx v5 "Topic Discovery" network +// warning: local bootnodes for testing!!! +var BootNodes = []*Node{ + //MustParseNode("enode://6f974ede10d07334e7e651c1501cb540d087dd3a6dea81432620895c913f281790b49459d72cb8011bfbbfbd24fad956356189c31b7181a96cd44ccfb68bfc71@127.0.0.1:30301"), + MustParseNode("enode://0cc5f5ffb5d9098c8b8c62325f3797f56509bff942704687b6530992ac706e2cb946b90a34f1f19548cd3c7baccbcaea354531e5983c7d1bc0dee16ce4b6440b@40.118.3.223:30305"), +} + +// Network manages the table and all protocol interaction. +type Network struct { + db *nodeDB // database of known nodes + conn transport + + closed chan struct{} // closed when loop is done + closeReq chan struct{} // 'request to close' + refreshReq chan []*Node // lookups ask for refresh on this channel + refreshResp chan (<-chan struct{}) // ...and get the channel to block on from this one + read chan ingressPacket // ingress packets arrive here + timeout chan timeoutEvent + queryReq chan *findnodeQuery // lookups submit findnode queries on this channel + tableOpReq chan func() + tableOpResp chan struct{} + topicRegisterReq chan topicRegisterReq + topicSearchReq chan topicSearchReq + bucketFillChn chan chan struct{} + + // State of the main loop. + tab *Table + topictab *topicTable + ticketStore *ticketStore + nursery []*Node + nodes map[NodeID]*Node // tracks active nodes with state != known + timeoutTimers map[timeoutEvent]*time.Timer + + // Revalidation queues. + // Nodes put on these queues will be pinged eventually. + slowRevalidateQueue []*Node + fastRevalidateQueue []*Node + + // Buffers for state transition. + sendBuf []*ingressPacket +} + +// transport is implemented by the UDP transport. +// it is an interface so we can test without opening lots of UDP +// sockets and without generating a private key. +type transport interface { + sendPing(remote *Node, remoteAddr *net.UDPAddr, topics []Topic) (hash []byte) + sendNeighbours(remote *Node, nodes []*Node) + sendFindnodeHash(remote *Node, target common.Hash) + sendTopicRegister(remote *Node, topics []Topic, topicIdx int, pong []byte) + sendTopicNodes(remote *Node, queryHash common.Hash, nodes []*Node) + + send(remote *Node, ptype nodeEvent, p interface{}) (hash []byte) + + localAddr() *net.UDPAddr + Close() +} + +type findnodeQuery struct { + remote *Node + target common.Hash + reply chan<- []*Node + nresults int // counter for received nodes +} + +type topicRegisterReq struct { + add bool + topic Topic +} + +type topicSearchReq struct { + topic Topic + found chan<- string +} + +type timeoutEvent struct { + ev nodeEvent + node *Node +} + +func newNetwork(conn transport, ourPubkey ecdsa.PublicKey, natm nat.Interface, dbPath string) (*Network, error) { + ourID := PubkeyID(&ourPubkey) + + var db *nodeDB + if dbPath != "<no database>" { + var err error + if db, err = newNodeDB(dbPath, Version, ourID); err != nil { + return nil, err + } + } + + tab := newTable(ourID, conn.localAddr()) + net := &Network{ + db: db, + conn: conn, + tab: tab, + topictab: newTopicTable(db, tab.self), + ticketStore: newTicketStore(), + refreshReq: make(chan []*Node), + refreshResp: make(chan (<-chan struct{})), + closed: make(chan struct{}), + closeReq: make(chan struct{}), + read: make(chan ingressPacket, 100), + timeout: make(chan timeoutEvent), + timeoutTimers: make(map[timeoutEvent]*time.Timer), + tableOpReq: make(chan func()), + tableOpResp: make(chan struct{}), + queryReq: make(chan *findnodeQuery), + topicRegisterReq: make(chan topicRegisterReq), + topicSearchReq: make(chan topicSearchReq), + bucketFillChn: make(chan chan struct{}, 1), + nodes: make(map[NodeID]*Node), + } + go net.loop() + return net, nil +} + +// Close terminates the network listener and flushes the node database. +func (net *Network) Close() { + net.conn.Close() + select { + case <-net.closed: + case net.closeReq <- struct{}{}: + <-net.closed + } +} + +// Self returns the local node. +// The returned node should not be modified by the caller. +func (net *Network) Self() *Node { + return net.tab.self +} + +// ReadRandomNodes fills the given slice with random nodes from the +// table. It will not write the same node more than once. The nodes in +// the slice are copies and can be modified by the caller. +func (net *Network) ReadRandomNodes(buf []*Node) (n int) { + net.reqTableOp(func() { n = net.tab.readRandomNodes(buf) }) + return n +} + +// SetFallbackNodes sets the initial points of contact. These nodes +// are used to connect to the network if the table is empty and there +// are no known nodes in the database. +func (net *Network) SetFallbackNodes(nodes []*Node) error { + nursery := make([]*Node, 0, len(nodes)) + for _, n := range nodes { + if err := n.validateComplete(); err != nil { + return fmt.Errorf("bad bootstrap/fallback node %q (%v)", n, err) + } + // Recompute cpy.sha because the node might not have been + // created by NewNode or ParseNode. + cpy := *n + cpy.sha = crypto.Keccak256Hash(n.ID[:]) + nursery = append(nursery, &cpy) + } + net.reqRefresh(nursery) + return nil +} + +// Resolve searches for a specific node with the given ID. +// It returns nil if the node could not be found. +func (net *Network) Resolve(targetID NodeID) *Node { + result := net.lookup(crypto.Keccak256Hash(targetID[:]), true) + for _, n := range result { + if n.ID == targetID { + return n + } + } + return nil +} + +// Lookup performs a network search for nodes close +// to the given target. It approaches the target by querying +// nodes that are closer to it on each iteration. +// The given target does not need to be an actual node +// identifier. +// +// The local node may be included in the result. +func (net *Network) Lookup(targetID NodeID) []*Node { + return net.lookup(crypto.Keccak256Hash(targetID[:]), false) +} + +func (net *Network) lookup(target common.Hash, stopOnMatch bool) []*Node { + var ( + asked = make(map[NodeID]bool) + seen = make(map[NodeID]bool) + reply = make(chan []*Node, alpha) + result = nodesByDistance{target: target} + pendingQueries = 0 + ) + // Get initial answers from the local node. + result.push(net.tab.self, bucketSize) + for { + // Ask the α closest nodes that we haven't asked yet. + for i := 0; i < len(result.entries) && pendingQueries < alpha; i++ { + n := result.entries[i] + if !asked[n.ID] { + asked[n.ID] = true + pendingQueries++ + net.reqQueryFindnode(n, target, reply) + } + } + if pendingQueries == 0 { + // We have asked all closest nodes, stop the search. + break + } + // Wait for the next reply. + for _, n := range <-reply { + if n != nil && !seen[n.ID] { + seen[n.ID] = true + result.push(n, bucketSize) + if stopOnMatch && n.sha == target { + return result.entries + } + } + } + pendingQueries-- + } + return result.entries +} + +func (net *Network) RegisterTopic(topic Topic, stop <-chan struct{}) { + select { + case net.topicRegisterReq <- topicRegisterReq{true, topic}: + case <-net.closed: + return + } + select { + case <-net.closed: + case <-stop: + select { + case net.topicRegisterReq <- topicRegisterReq{false, topic}: + case <-net.closed: + } + } +} + +func (net *Network) SearchTopic(topic Topic, stop <-chan struct{}, found chan<- string) { + select { + case net.topicSearchReq <- topicSearchReq{topic, found}: + case <-net.closed: + return + } + select { + case <-net.closed: + case <-stop: + select { + case net.topicSearchReq <- topicSearchReq{topic, nil}: + case <-net.closed: + } + } +} + +func (net *Network) reqRefresh(nursery []*Node) <-chan struct{} { + select { + case net.refreshReq <- nursery: + return <-net.refreshResp + case <-net.closed: + return net.closed + } +} + +func (net *Network) reqQueryFindnode(n *Node, target common.Hash, reply chan []*Node) bool { + q := &findnodeQuery{remote: n, target: target, reply: reply} + select { + case net.queryReq <- q: + return true + case <-net.closed: + return false + } +} + +func (net *Network) reqReadPacket(pkt ingressPacket) { + select { + case net.read <- pkt: + case <-net.closed: + } +} + +func (net *Network) reqTableOp(f func()) (called bool) { + select { + case net.tableOpReq <- f: + <-net.tableOpResp + return true + case <-net.closed: + return false + } +} + +// TODO: external address handling. + +func (net *Network) loop() { + var ( + refreshTimer = time.NewTicker(autoRefreshInterval) + refreshDone chan struct{} // closed when the 'refresh' lookup has ended + ) + + // Tracking the next ticket to register. + var ( + nextTicket *ticketRef + nextRegisterTimer *time.Timer + nextRegisterTime <-chan time.Time + ) + defer func() { + if nextRegisterTimer != nil { + nextRegisterTimer.Stop() + } + }() + resetNextTicket := func() { + t, timeout := net.ticketStore.nextFilteredTicket() + if t != nextTicket { + nextTicket = t + if nextRegisterTimer != nil { + nextRegisterTimer.Stop() + nextRegisterTime = nil + } + if t != nil { + nextRegisterTimer = time.NewTimer(timeout) + nextRegisterTime = nextRegisterTimer.C + } + } + } + + // Tracking registration and search lookups. + var ( + topicRegisterLookupTarget lookupInfo + topicRegisterLookupDone chan []*Node + topicRegisterLookupTick = time.NewTimer(0) + topicSearchLookupTarget lookupInfo + ) + topicSearchLookupDone := make(chan []*Node, 1) + <-topicRegisterLookupTick.C + + statsDump := time.NewTicker(10 * time.Second) + +loop: + for { + resetNextTicket() + + select { + case <-net.closeReq: + debugLog("<-net.closeReq") + break loop + + // Ingress packet handling. + case pkt := <-net.read: + debugLog("<-net.read") + n := net.internNode(&pkt) + prestate := n.state + status := "ok" + if err := net.handle(n, pkt.ev, &pkt); err != nil { + status = err.Error() + } + if glog.V(logger.Detail) { + glog.Infof("<<< (%d) %v from %x@%v: %v -> %v (%v)", + net.tab.count, pkt.ev, pkt.remoteID[:8], pkt.remoteAddr, prestate, n.state, status) + } + // TODO: persist state if n.state goes >= known, delete if it goes <= known + + // State transition timeouts. + case timeout := <-net.timeout: + debugLog("<-net.timeout") + if net.timeoutTimers[timeout] == nil { + // Stale timer (was aborted). + continue + } + delete(net.timeoutTimers, timeout) + prestate := timeout.node.state + status := "ok" + if err := net.handle(timeout.node, timeout.ev, nil); err != nil { + status = err.Error() + } + if glog.V(logger.Detail) { + glog.Infof("--- (%d) %v for %x@%v: %v -> %v (%v)", + net.tab.count, timeout.ev, timeout.node.ID[:8], timeout.node.addr(), prestate, timeout.node.state, status) + } + + // Querying. + case q := <-net.queryReq: + debugLog("<-net.queryReq") + if !q.start(net) { + q.remote.deferQuery(q) + } + + // Interacting with the table. + case f := <-net.tableOpReq: + debugLog("<-net.tableOpReq") + f() + net.tableOpResp <- struct{}{} + + // Topic registration stuff. + case req := <-net.topicRegisterReq: + debugLog("<-net.topicRegisterReq") + if !req.add { + net.ticketStore.removeRegisterTopic(req.topic) + continue + } + net.ticketStore.addTopic(req.topic, true) + // If we're currently waiting idle (nothing to look up), give the ticket store a + // chance to start it sooner. This should speed up convergence of the radius + // determination for new topics. + // if topicRegisterLookupDone == nil { + if topicRegisterLookupTarget.target == (common.Hash{}) { + debugLog("topicRegisterLookupTarget == null") + if topicRegisterLookupTick.Stop() { + <-topicRegisterLookupTick.C + } + target, delay := net.ticketStore.nextRegisterLookup() + topicRegisterLookupTarget = target + topicRegisterLookupTick.Reset(delay) + } + + case nodes := <-topicRegisterLookupDone: + debugLog("<-topicRegisterLookupDone") + net.ticketStore.registerLookupDone(topicRegisterLookupTarget, nodes, func(n *Node) []byte { + net.ping(n, n.addr()) + return n.pingEcho + }) + target, delay := net.ticketStore.nextRegisterLookup() + topicRegisterLookupTarget = target + topicRegisterLookupTick.Reset(delay) + topicRegisterLookupDone = nil + + case <-topicRegisterLookupTick.C: + debugLog("<-topicRegisterLookupTick") + if (topicRegisterLookupTarget.target == common.Hash{}) { + target, delay := net.ticketStore.nextRegisterLookup() + topicRegisterLookupTarget = target + topicRegisterLookupTick.Reset(delay) + topicRegisterLookupDone = nil + } else { + topicRegisterLookupDone = make(chan []*Node) + target := topicRegisterLookupTarget.target + go func() { topicRegisterLookupDone <- net.lookup(target, false) }() + } + + case <-nextRegisterTime: + debugLog("<-nextRegisterTime") + net.ticketStore.ticketRegistered(*nextTicket) + //fmt.Println("sendTopicRegister", nextTicket.t.node.addr().String(), nextTicket.t.topics, nextTicket.idx, nextTicket.t.pong) + net.conn.sendTopicRegister(nextTicket.t.node, nextTicket.t.topics, nextTicket.idx, nextTicket.t.pong) + + case req := <-net.topicSearchReq: + debugLog("<-net.topicSearchReq") + if req.found == nil { + net.ticketStore.removeSearchTopic(req.topic) + continue + } + net.ticketStore.addSearchTopic(req.topic, req.found) + if (topicSearchLookupTarget.target == common.Hash{}) { + topicSearchLookupDone <- nil + } + + case nodes := <-topicSearchLookupDone: + debugLog("<-topicSearchLookupDone") + net.ticketStore.searchLookupDone(topicSearchLookupTarget, nodes, func(n *Node) []byte { + net.ping(n, n.addr()) + return n.pingEcho + }, func(n *Node, topic Topic) []byte { + return net.conn.send(n, topicQueryPacket, topicQuery{Topic: topic}) // TODO: set expiration + }) + topicSearchLookupTarget = net.ticketStore.nextSearchLookup() + target := topicSearchLookupTarget.target + if (target != common.Hash{}) { + go func() { topicSearchLookupDone <- net.lookup(target, false) }() + } + + case <-statsDump.C: + debugLog("<-statsDump.C") + /*r, ok := net.ticketStore.radius[testTopic] + if !ok { + fmt.Printf("(%x) no radius @ %v\n", net.tab.self.ID[:8], time.Now()) + } else { + topics := len(net.ticketStore.tickets) + tickets := len(net.ticketStore.nodes) + rad := r.radius / (maxRadius/10000+1) + fmt.Printf("(%x) topics:%d radius:%d tickets:%d @ %v\n", net.tab.self.ID[:8], topics, rad, tickets, time.Now()) + }*/ + + tm := mclock.Now() + for topic, r := range net.ticketStore.radius { + if printTestImgLogs { + rad := r.radius / (maxRadius/1000000 + 1) + minrad := r.minRadius / (maxRadius/1000000 + 1) + fmt.Printf("*R %d %v %016x %v\n", tm/1000000, topic, net.tab.self.sha[:8], rad) + fmt.Printf("*MR %d %v %016x %v\n", tm/1000000, topic, net.tab.self.sha[:8], minrad) + } + } + for topic, t := range net.topictab.topics { + wp := t.wcl.nextWaitPeriod(tm) + if printTestImgLogs { + fmt.Printf("*W %d %v %016x %d\n", tm/1000000, topic, net.tab.self.sha[:8], wp/1000000) + } + } + + // Periodic / lookup-initiated bucket refresh. + case <-refreshTimer.C: + debugLog("<-refreshTimer.C") + // TODO: ideally we would start the refresh timer after + // fallback nodes have been set for the first time. + if refreshDone == nil { + refreshDone = make(chan struct{}) + net.refresh(refreshDone) + } + case doneChn := <-net.bucketFillChn: + debugLog("bucketFill") + net.bucketFill(doneChn) + case newNursery := <-net.refreshReq: + debugLog("<-net.refreshReq") + if newNursery != nil { + net.nursery = newNursery + } + if refreshDone == nil { + refreshDone = make(chan struct{}) + net.refresh(refreshDone) + } + net.refreshResp <- refreshDone + case <-refreshDone: + debugLog("<-net.refreshDone") + refreshDone = nil + } + } + debugLog("loop stopped") + + glog.V(logger.Debug).Infof("shutting down") + if net.conn != nil { + net.conn.Close() + } + if refreshDone != nil { + // TODO: wait for pending refresh. + //<-refreshResults + } + // Cancel all pending timeouts. + for _, timer := range net.timeoutTimers { + timer.Stop() + } + if net.db != nil { + net.db.close() + } + close(net.closed) +} + +// Everything below runs on the Network.loop goroutine +// and can modify Node, Table and Network at any time without locking. + +func (net *Network) refresh(done chan<- struct{}) { + var seeds []*Node + if net.db != nil { + seeds = net.db.querySeeds(seedCount, seedMaxAge) + } + if len(seeds) == 0 { + seeds = net.nursery + } + if len(seeds) == 0 { + glog.V(logger.Detail).Info("no seed nodes found") + close(done) + return + } + for _, n := range seeds { + if glog.V(logger.Debug) { + var age string + if net.db != nil { + age = time.Since(net.db.lastPong(n.ID)).String() + } else { + age = "unknown" + } + glog.Infof("seed node (age %s): %v", age, n) + } + n = net.internNodeFromDB(n) + if n.state == unknown { + net.transition(n, verifyinit) + } + // Force-add the seed node so Lookup does something. + // It will be deleted again if verification fails. + net.tab.add(n) + } + // Start self lookup to fill up the buckets. + go func() { + net.Lookup(net.tab.self.ID) + close(done) + }() +} + +func (net *Network) bucketFill(done chan<- struct{}) { + target := net.tab.chooseBucketFillTarget() + go func() { + net.lookup(target, false) + close(done) + }() +} + +func (net *Network) BucketFill() { + done := make(chan struct{}) + select { + case net.bucketFillChn <- done: + <-done + case <-net.closed: + close(done) + } +} + +// Node Interning. + +func (net *Network) internNode(pkt *ingressPacket) *Node { + if n := net.nodes[pkt.remoteID]; n != nil { + return n + } + n := NewNode(pkt.remoteID, pkt.remoteAddr.IP, uint16(pkt.remoteAddr.Port), uint16(pkt.remoteAddr.Port)) + n.state = unknown + net.nodes[pkt.remoteID] = n + return n +} + +func (net *Network) internNodeFromDB(dbn *Node) *Node { + if n := net.nodes[dbn.ID]; n != nil { + return n + } + n := NewNode(dbn.ID, dbn.IP, dbn.UDP, dbn.TCP) + n.state = unknown + net.nodes[n.ID] = n + return n +} + +func (net *Network) internNodeFromNeighbours(rn rpcNode) (n *Node, err error) { + if rn.ID == net.tab.self.ID { + return nil, errors.New("is self") + } + n = net.nodes[rn.ID] + if n == nil { + // We haven't seen this node before. + n, err = nodeFromRPC(rn) + n.state = unknown + if err == nil { + net.nodes[n.ID] = n + } + return n, err + } + if !bytes.Equal(n.IP, rn.IP) || n.UDP != rn.UDP || n.TCP != rn.TCP { + err = fmt.Errorf("metadata mismatch: got %v, want %v", rn, n) + } + return n, err +} + +// nodeNetGuts is embedded in Node and contains fields. +type nodeNetGuts struct { + // This is a cached copy of sha3(ID) which is used for node + // distance calculations. This is part of Node in order to make it + // possible to write tests that need a node at a certain distance. + // In those tests, the content of sha will not actually correspond + // with ID. + sha common.Hash + + // State machine fields. Access to these fields + // is restricted to the Network.loop goroutine. + state *nodeState + pingEcho []byte // hash of last ping sent by us + pingTopics []Topic // topic set sent by us in last ping + deferredQueries []*findnodeQuery // queries that can't be sent yet + pendingNeighbours *findnodeQuery // current query, waiting for reply + queryTimeouts int +} + +func (n *nodeNetGuts) deferQuery(q *findnodeQuery) { + n.deferredQueries = append(n.deferredQueries, q) +} + +func (n *nodeNetGuts) startNextQuery(net *Network) { + if len(n.deferredQueries) == 0 { + return + } + nextq := n.deferredQueries[0] + if nextq.start(net) { + n.deferredQueries = append(n.deferredQueries[:0], n.deferredQueries[1:]...) + } +} + +func (q *findnodeQuery) start(net *Network) bool { + // Satisfy queries against the local node directly. + if q.remote == net.tab.self { + closest := net.tab.closest(crypto.Keccak256Hash(q.target[:]), bucketSize) + q.reply <- closest.entries + return true + } + if q.remote.state.canQuery && q.remote.pendingNeighbours == nil { + net.conn.sendFindnodeHash(q.remote, q.target) + net.timedEvent(respTimeout, q.remote, neighboursTimeout) + q.remote.pendingNeighbours = q + return true + } + // If the node is not known yet, it won't accept queries. + // Initiate the transition to known. + // The request will be sent later when the node reaches known state. + if q.remote.state == unknown { + net.transition(q.remote, verifyinit) + } + return false +} + +// Node Events (the input to the state machine). + +type nodeEvent uint + +//go:generate stringer -type=nodeEvent + +const ( + invalidEvent nodeEvent = iota // zero is reserved + + // Packet type events. + // These correspond to packet types in the UDP protocol. + pingPacket + pongPacket + findnodePacket + neighborsPacket + findnodeHashPacket + topicRegisterPacket + topicQueryPacket + topicNodesPacket + + // Non-packet events. + // Event values in this category are allocated outside + // the packet type range (packet types are encoded as a single byte). + pongTimeout nodeEvent = iota + 256 + pingTimeout + neighboursTimeout +) + +// Node State Machine. + +type nodeState struct { + name string + handle func(*Network, *Node, nodeEvent, *ingressPacket) (next *nodeState, err error) + enter func(*Network, *Node) + canQuery bool +} + +func (s *nodeState) String() string { + return s.name +} + +var ( + unknown *nodeState + verifyinit *nodeState + verifywait *nodeState + remoteverifywait *nodeState + known *nodeState + contested *nodeState + unresponsive *nodeState +) + +func init() { + unknown = &nodeState{ + name: "unknown", + enter: func(net *Network, n *Node) { + net.tab.delete(n) + n.pingEcho = nil + // Abort active queries. + for _, q := range n.deferredQueries { + q.reply <- nil + } + n.deferredQueries = nil + if n.pendingNeighbours != nil { + n.pendingNeighbours.reply <- nil + n.pendingNeighbours = nil + } + n.queryTimeouts = 0 + }, + handle: func(net *Network, n *Node, ev nodeEvent, pkt *ingressPacket) (*nodeState, error) { + switch ev { + case pingPacket: + net.handlePing(n, pkt) + net.ping(n, pkt.remoteAddr) + return verifywait, nil + default: + return unknown, errInvalidEvent + } + }, + } + + verifyinit = &nodeState{ + name: "verifyinit", + enter: func(net *Network, n *Node) { + net.ping(n, n.addr()) + }, + handle: func(net *Network, n *Node, ev nodeEvent, pkt *ingressPacket) (*nodeState, error) { + switch ev { + case pingPacket: + net.handlePing(n, pkt) + return verifywait, nil + case pongPacket: + err := net.handleKnownPong(n, pkt) + return remoteverifywait, err + case pongTimeout: + return unknown, nil + default: + return verifyinit, errInvalidEvent + } + }, + } + + verifywait = &nodeState{ + name: "verifywait", + handle: func(net *Network, n *Node, ev nodeEvent, pkt *ingressPacket) (*nodeState, error) { + switch ev { + case pongPacket: + err := net.handleKnownPong(n, pkt) + return known, err + case pongTimeout: + return unknown, nil + default: + return verifywait, errInvalidEvent + } + }, + } + + remoteverifywait = &nodeState{ + name: "remoteverifywait", + enter: func(net *Network, n *Node) { + net.timedEvent(respTimeout, n, pingTimeout) + }, + handle: func(net *Network, n *Node, ev nodeEvent, pkt *ingressPacket) (*nodeState, error) { + switch ev { + case pingPacket: + net.handlePing(n, pkt) + return remoteverifywait, nil + case pingTimeout: + return known, nil + default: + return remoteverifywait, errInvalidEvent + } + }, + } + + known = &nodeState{ + name: "known", + canQuery: true, + enter: func(net *Network, n *Node) { + n.queryTimeouts = 0 + n.startNextQuery(net) + // Insert into the table and start revalidation of the last node + // in the bucket if it is full. + last := net.tab.add(n) + if last != nil && last.state == known { + // TODO: do this asynchronously + net.transition(last, contested) + } + }, + handle: func(net *Network, n *Node, ev nodeEvent, pkt *ingressPacket) (*nodeState, error) { + switch ev { + case pingPacket: + net.handlePing(n, pkt) + return known, nil + case pongPacket: + err := net.handleKnownPong(n, pkt) + return known, err + default: + return net.handleQueryEvent(n, ev, pkt) + } + }, + } + + contested = &nodeState{ + name: "contested", + canQuery: true, + enter: func(net *Network, n *Node) { + net.ping(n, n.addr()) + }, + handle: func(net *Network, n *Node, ev nodeEvent, pkt *ingressPacket) (*nodeState, error) { + switch ev { + case pongPacket: + // Node is still alive. + err := net.handleKnownPong(n, pkt) + return known, err + case pongTimeout: + net.tab.deleteReplace(n) + return unresponsive, nil + case pingPacket: + net.handlePing(n, pkt) + return contested, nil + default: + return net.handleQueryEvent(n, ev, pkt) + } + }, + } + + unresponsive = &nodeState{ + name: "unresponsive", + canQuery: true, + handle: func(net *Network, n *Node, ev nodeEvent, pkt *ingressPacket) (*nodeState, error) { + switch ev { + case pingPacket: + net.handlePing(n, pkt) + return known, nil + case pongPacket: + err := net.handleKnownPong(n, pkt) + return known, err + default: + return net.handleQueryEvent(n, ev, pkt) + } + }, + } +} + +// handle processes packets sent by n and events related to n. +func (net *Network) handle(n *Node, ev nodeEvent, pkt *ingressPacket) error { + if pkt != nil { + if err := net.checkPacket(n, ev, pkt); err != nil { + return err + } + // Start the background expiration goroutine after the first + // successful communication. Subsequent calls have no effect if it + // is already running. We do this here instead of somewhere else + // so that the search for seed nodes also considers older nodes + // that would otherwise be removed by the expirer. + if net.db != nil { + net.db.ensureExpirer() + } + } + if n.state == nil { + n.state = unknown //??? + } + next, err := n.state.handle(net, n, ev, pkt) + net.transition(n, next) + return err +} + +func (net *Network) checkPacket(n *Node, ev nodeEvent, pkt *ingressPacket) error { + // Replay prevention checks. + switch ev { + case pingPacket, findnodeHashPacket, neighborsPacket: + // TODO: check date is > last date seen + // TODO: check ping version + case pongPacket: + if !bytes.Equal(pkt.data.(*pong).ReplyTok, n.pingEcho) { + // fmt.Println("pong reply token mismatch") + return fmt.Errorf("pong reply token mismatch") + } + n.pingEcho = nil + } + // Address validation. + // TODO: Ideally we would do the following: + // - reject all packets with wrong address except ping. + // - for ping with new address, transition to verifywait but keep the + // previous node (with old address) around. if the new one reaches known, + // swap it out. + return nil +} + +func (net *Network) transition(n *Node, next *nodeState) { + if n.state != next { + n.state = next + if next.enter != nil { + next.enter(net, n) + } + } + + // TODO: persist/unpersist node +} + +func (net *Network) timedEvent(d time.Duration, n *Node, ev nodeEvent) { + timeout := timeoutEvent{ev, n} + net.timeoutTimers[timeout] = time.AfterFunc(d, func() { + select { + case net.timeout <- timeout: + case <-net.closed: + } + }) +} + +func (net *Network) abortTimedEvent(n *Node, ev nodeEvent) { + timer := net.timeoutTimers[timeoutEvent{ev, n}] + if timer != nil { + timer.Stop() + delete(net.timeoutTimers, timeoutEvent{ev, n}) + } +} + +func (net *Network) ping(n *Node, addr *net.UDPAddr) { + debugLog(fmt.Sprintf("ping(node = %x)", n.ID[:8])) + n.pingTopics = net.ticketStore.regTopicSet() + n.pingEcho = net.conn.sendPing(n, addr, n.pingTopics) + net.timedEvent(respTimeout, n, pongTimeout) +} + +func (net *Network) handlePing(n *Node, pkt *ingressPacket) { + debugLog(fmt.Sprintf("handlePing(node = %x)", n.ID[:8])) + ping := pkt.data.(*ping) + n.TCP = ping.From.TCP + t := net.topictab.getTicket(n, ping.Topics) + + pong := &pong{ + To: makeEndpoint(n.addr(), n.TCP), // TODO: maybe use known TCP port from DB + ReplyTok: pkt.hash, + Expiration: uint64(time.Now().Add(expiration).Unix()), + } + ticketToPong(t, pong) + net.conn.send(n, pongPacket, pong) +} + +func (net *Network) handleKnownPong(n *Node, pkt *ingressPacket) error { + debugLog(fmt.Sprintf("handleKnownPong(node = %x)", n.ID[:8])) + net.abortTimedEvent(n, pongTimeout) + now := mclock.Now() + ticket, err := pongToTicket(now, n.pingTopics, n, pkt) + if err == nil { + // fmt.Printf("(%x) ticket: %+v\n", net.tab.self.ID[:8], pkt.data) + net.ticketStore.addTicket(now, pkt.data.(*pong).ReplyTok, ticket) + } else { + debugLog(fmt.Sprintf(" error: %v", err)) + } + + n.pingEcho = nil + n.pingTopics = nil + return err +} + +func (net *Network) handleQueryEvent(n *Node, ev nodeEvent, pkt *ingressPacket) (*nodeState, error) { + switch ev { + case findnodePacket: + target := crypto.Keccak256Hash(pkt.data.(*findnode).Target[:]) + results := net.tab.closest(target, bucketSize).entries + net.conn.sendNeighbours(n, results) + return n.state, nil + case neighborsPacket: + err := net.handleNeighboursPacket(n, pkt.data.(*neighbors)) + return n.state, err + case neighboursTimeout: + if n.pendingNeighbours != nil { + n.pendingNeighbours.reply <- nil + n.pendingNeighbours = nil + } + n.queryTimeouts++ + if n.queryTimeouts > maxFindnodeFailures && n.state == known { + return contested, errors.New("too many timeouts") + } + return n.state, nil + + // v5 + + case findnodeHashPacket: + results := net.tab.closest(pkt.data.(*findnodeHash).Target, bucketSize).entries + net.conn.sendNeighbours(n, results) + return n.state, nil + case topicRegisterPacket: + //fmt.Println("got topicRegisterPacket") + regdata := pkt.data.(*topicRegister) + pong, err := net.checkTopicRegister(regdata) + if err != nil { + //fmt.Println(err) + return n.state, fmt.Errorf("bad waiting ticket: %v", err) + } + net.topictab.useTicket(n, pong.TicketSerial, regdata.Topics, int(regdata.Idx), pong.Expiration, pong.WaitPeriods) + return n.state, nil + case topicQueryPacket: + // TODO: handle expiration + topic := pkt.data.(*topicQuery).Topic + results := net.topictab.getEntries(topic) + if _, ok := net.ticketStore.tickets[topic]; ok { + results = append(results, net.tab.self) // we're not registering in our own table but if we're advertising, return ourselves too + } + if len(results) > 10 { + results = results[:10] + } + var hash common.Hash + copy(hash[:], pkt.hash) + net.conn.sendTopicNodes(n, hash, results) + return n.state, nil + case topicNodesPacket: + p := pkt.data.(*topicNodes) + if net.ticketStore.gotTopicNodes(n, p.Echo, p.Nodes) { + n.queryTimeouts++ + if n.queryTimeouts > maxFindnodeFailures && n.state == known { + return contested, errors.New("too many timeouts") + } + } + return n.state, nil + + default: + return n.state, errInvalidEvent + } +} + +func (net *Network) checkTopicRegister(data *topicRegister) (*pong, error) { + var pongpkt ingressPacket + if err := decodePacket(data.Pong, &pongpkt); err != nil { + return nil, err + } + if pongpkt.ev != pongPacket { + return nil, errors.New("is not pong packet") + } + if pongpkt.remoteID != net.tab.self.ID { + return nil, errors.New("not signed by us") + } + // check that we previously authorised all topics + // that the other side is trying to register. + if rlpHash(data.Topics) != pongpkt.data.(*pong).TopicHash { + return nil, errors.New("topic hash mismatch") + } + if data.Idx < 0 || int(data.Idx) >= len(data.Topics) { + return nil, errors.New("topic index out of range") + } + return pongpkt.data.(*pong), nil +} + +func rlpHash(x interface{}) (h common.Hash) { + hw := sha3.NewKeccak256() + rlp.Encode(hw, x) + hw.Sum(h[:0]) + return h +} + +func (net *Network) handleNeighboursPacket(n *Node, req *neighbors) error { + if n.pendingNeighbours == nil { + return errNoQuery + } + net.abortTimedEvent(n, neighboursTimeout) + + nodes := make([]*Node, len(req.Nodes)) + for i, rn := range req.Nodes { + nn, err := net.internNodeFromNeighbours(rn) + if err != nil { + glog.V(logger.Debug).Infof("invalid neighbour from %x: %v", n.ID[:8], err) + continue + } + nodes[i] = nn + // Start validation of query results immediately. + // This fills the table quickly. + // TODO: generates way too many packets, maybe do it via queue. + if nn.state == unknown { + net.transition(nn, verifyinit) + } + } + // TODO: don't ignore second packet + n.pendingNeighbours.reply <- nodes + n.pendingNeighbours = nil + // Now that this query is done, start the next one. + n.startNextQuery(net) + return nil +} |