p2p, p2p/discover: add signed ENR generation (#17753)

This PR adds enode.LocalNode and integrates it into the p2p
subsystem. This new object is the keeper of the local node
record. For now, a new version of the record is produced every
time the client restarts. We'll make it smarter to avoid that in
the future.

There are a couple of other changes in this commit: discovery now
waits for all of its goroutines at shutdown and the p2p server
now closes the node database after discovery has shut down. This
fixes a leveldb crash in tests. p2p server startup is faster
because it doesn't need to wait for the external IP query
anymore.

1 files changed, 22 insertions, 19 deletions

diff --git a/p2p/discover/table.go b/p2p/discover/table.go
index 7a3e41de1..afd4c9a27 100644
--- a/p2p/discover/table.go
+++ b/p2p/discover/table.go
@@ -72,21 +72,20 @@ type Table struct {
 	ips     netutil.DistinctNetSet
 
 	db         *enode.DB // database of known nodes
+	net        transport
 	refreshReq chan chan struct{}
 	initDone   chan struct{}
 	closeReq   chan struct{}
 	closed     chan struct{}
 
 	nodeAddedHook func(*node) // for testing
-
-	net  transport
-	self *node // metadata of the local node
 }
 
 // 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 {
+	self() *enode.Node
 	ping(enode.ID, *net.UDPAddr) error
 	findnode(toid enode.ID, addr *net.UDPAddr, target encPubkey) ([]*node, error)
 	close()
@@ -100,11 +99,10 @@ type bucket struct {
 	ips          netutil.DistinctNetSet
 }
 
-func newTable(t transport, self *enode.Node, db *enode.DB, bootnodes []*enode.Node) (*Table, error) {
+func newTable(t transport, db *enode.DB, bootnodes []*enode.Node) (*Table, error) {
 	tab := &Table{
 		net:        t,
 		db:         db,
-		self:       wrapNode(self),
 		refreshReq: make(chan chan struct{}),
 		initDone:   make(chan struct{}),
 		closeReq:   make(chan struct{}),
@@ -127,6 +125,10 @@ func newTable(t transport, self *enode.Node, db *enode.DB, bootnodes []*enode.No
 	return tab, nil
 }
 
+func (tab *Table) self() *enode.Node {
+	return tab.net.self()
+}
+
 func (tab *Table) seedRand() {
 	var b [8]byte
 	crand.Read(b[:])
@@ -136,11 +138,6 @@ func (tab *Table) seedRand() {
 	tab.mutex.Unlock()
 }
 
-// Self returns the local node.
-func (tab *Table) Self() *enode.Node {
-	return unwrapNode(tab.self)
-}
-
 // ReadRandomNodes fills the given slice with random nodes from the table. The results
 // are guaranteed to be unique for a single invocation, no node will appear twice.
 func (tab *Table) ReadRandomNodes(buf []*enode.Node) (n int) {
@@ -183,6 +180,10 @@ func (tab *Table) ReadRandomNodes(buf []*enode.Node) (n int) {
 
 // Close terminates the network listener and flushes the node database.
 func (tab *Table) Close() {
+	if tab.net != nil {
+		tab.net.close()
+	}
+
 	select {
 	case <-tab.closed:
 		// already closed.
@@ -257,7 +258,7 @@ func (tab *Table) lookup(targetKey encPubkey, refreshIfEmpty bool) []*node {
 	)
 	// don't query further if we hit ourself.
 	// unlikely to happen often in practice.
-	asked[tab.self.ID()] = true
+	asked[tab.self().ID()] = true
 
 	for {
 		tab.mutex.Lock()
@@ -340,8 +341,8 @@ func (tab *Table) loop() {
 		revalidate     = time.NewTimer(tab.nextRevalidateTime())
 		refresh        = time.NewTicker(refreshInterval)
 		copyNodes      = time.NewTicker(copyNodesInterval)
-		revalidateDone = make(chan struct{})
 		refreshDone    = make(chan struct{})           // where doRefresh reports completion
+		revalidateDone chan struct{}                   // where doRevalidate reports completion
 		waiting        = []chan struct{}{tab.initDone} // holds waiting callers while doRefresh runs
 	)
 	defer refresh.Stop()
@@ -372,9 +373,11 @@ loop:
 			}
 			waiting, refreshDone = nil, nil
 		case <-revalidate.C:
+			revalidateDone = make(chan struct{})
 			go tab.doRevalidate(revalidateDone)
 		case <-revalidateDone:
 			revalidate.Reset(tab.nextRevalidateTime())
+			revalidateDone = nil
 		case <-copyNodes.C:
 			go tab.copyLiveNodes()
 		case <-tab.closeReq:
@@ -382,15 +385,15 @@ loop:
 		}
 	}
 
-	if tab.net != nil {
-		tab.net.close()
-	}
 	if refreshDone != nil {
 		<-refreshDone
 	}
 	for _, ch := range waiting {
 		close(ch)
 	}
+	if revalidateDone != nil {
+		<-revalidateDone
+	}
 	close(tab.closed)
 }
 
@@ -408,7 +411,7 @@ func (tab *Table) doRefresh(done chan struct{}) {
 	// Run self lookup to discover new neighbor nodes.
 	// We can only do this if we have a secp256k1 identity.
 	var key ecdsa.PublicKey
-	if err := tab.self.Load((*enode.Secp256k1)(&key)); err == nil {
+	if err := tab.self().Load((*enode.Secp256k1)(&key)); err == nil {
 		tab.lookup(encodePubkey(&key), false)
 	}
 
@@ -530,7 +533,7 @@ func (tab *Table) len() (n int) {
 
 // bucket returns the bucket for the given node ID hash.
 func (tab *Table) bucket(id enode.ID) *bucket {
-	d := enode.LogDist(tab.self.ID(), id)
+	d := enode.LogDist(tab.self().ID(), id)
 	if d <= bucketMinDistance {
 		return tab.buckets[0]
 	}
@@ -543,7 +546,7 @@ func (tab *Table) bucket(id enode.ID) *bucket {
 //
 // The caller must not hold tab.mutex.
 func (tab *Table) add(n *node) {
-	if n.ID() == tab.self.ID() {
+	if n.ID() == tab.self().ID() {
 		return
 	}
 
@@ -576,7 +579,7 @@ func (tab *Table) stuff(nodes []*node) {
 	defer tab.mutex.Unlock()
 
 	for _, n := range nodes {
-		if n.ID() == tab.self.ID() {
+		if n.ID() == tab.self().ID() {
 			continue // don't add self
 		}
 		b := tab.bucket(n.ID())