p2p: new dialer, peer management without locks

The most visible change is event-based dialing, which should be an
improvement over the timer-based system that we have at the moment.
The dialer gets a chance to compute new tasks whenever peers change or
dials complete. This is better than checking peers on a timer because
dials happen faster. The dialer can now make more precise decisions
about whom to dial based on the peer set and we can test those
decisions without actually opening any sockets.

Peer management is easier to test because the tests can inject
connections at checkpoints (after enc handshake, after protocol
handshake).

Most of the handshake stuff is now part of the RLPx code. It could be
exported or move to its own package because it is no longer entangled
with Server logic.

1 files changed, 482 insertions, 0 deletions

diff --git a/p2p/dial_test.go b/p2p/dial_test.go
new file mode 100644
index 000000000..78568c5ed
--- /dev/null
+++ b/p2p/dial_test.go
@@ -0,0 +1,482 @@
+package p2p
+
+import (
+	"encoding/binary"
+	"reflect"
+	"testing"
+	"time"
+
+	"github.com/davecgh/go-spew/spew"
+	"github.com/ethereum/go-ethereum/p2p/discover"
+)
+
+func init() {
+	spew.Config.Indent = "\t"
+}
+
+type dialtest struct {
+	init   *dialstate // state before and after the test.
+	rounds []round
+}
+
+type round struct {
+	peers []*Peer // current peer set
+	done  []task  // tasks that got done this round
+	new   []task  // the result must match this one
+}
+
+func runDialTest(t *testing.T, test dialtest) {
+	var (
+		vtime   time.Time
+		running int
+	)
+	pm := func(ps []*Peer) map[discover.NodeID]*Peer {
+		m := make(map[discover.NodeID]*Peer)
+		for _, p := range ps {
+			m[p.rw.id] = p
+		}
+		return m
+	}
+	for i, round := range test.rounds {
+		for _, task := range round.done {
+			running--
+			if running < 0 {
+				panic("running task counter underflow")
+			}
+			test.init.taskDone(task, vtime)
+		}
+
+		new := test.init.newTasks(running, pm(round.peers), vtime)
+		if !sametasks(new, round.new) {
+			t.Errorf("round %d: new tasks mismatch:\ngot %v\nwant %v\nstate: %v\nrunning: %v\n",
+				i, spew.Sdump(new), spew.Sdump(round.new), spew.Sdump(test.init), spew.Sdump(running))
+		}
+
+		// Time advances by 16 seconds on every round.
+		vtime = vtime.Add(16 * time.Second)
+		running += len(new)
+	}
+}
+
+type fakeTable []*discover.Node
+
+func (t fakeTable) Self() *discover.Node       { return new(discover.Node) }
+func (t fakeTable) Close()                     {}
+func (t fakeTable) Bootstrap([]*discover.Node) {}
+func (t fakeTable) Lookup(target discover.NodeID) []*discover.Node {
+	return nil
+}
+func (t fakeTable) ReadRandomNodes(buf []*discover.Node) int {
+	return copy(buf, t)
+}
+
+// This test checks that dynamic dials are launched from discovery results.
+func TestDialStateDynDial(t *testing.T) {
+	runDialTest(t, dialtest{
+		init: newDialState(nil, fakeTable{}, 5),
+		rounds: []round{
+			// A discovery query is launched.
+			{
+				peers: []*Peer{
+					{rw: &conn{flags: staticDialedConn, id: uintID(0)}},
+					{rw: &conn{flags: dynDialedConn, id: uintID(1)}},
+					{rw: &conn{flags: dynDialedConn, id: uintID(2)}},
+				},
+				new: []task{&discoverTask{bootstrap: true}},
+			},
+			// Dynamic dials are launched when it completes.
+			{
+				peers: []*Peer{
+					{rw: &conn{flags: staticDialedConn, id: uintID(0)}},
+					{rw: &conn{flags: dynDialedConn, id: uintID(1)}},
+					{rw: &conn{flags: dynDialedConn, id: uintID(2)}},
+				},
+				done: []task{
+					&discoverTask{bootstrap: true, results: []*discover.Node{
+						{ID: uintID(2)}, // this one is already connected and not dialed.
+						{ID: uintID(3)},
+						{ID: uintID(4)},
+						{ID: uintID(5)},
+						{ID: uintID(6)}, // these are not tried because max dyn dials is 5
+						{ID: uintID(7)}, // ...
+					}},
+				},
+				new: []task{
+					&dialTask{dynDialedConn, &discover.Node{ID: uintID(3)}},
+					&dialTask{dynDialedConn, &discover.Node{ID: uintID(4)}},
+					&dialTask{dynDialedConn, &discover.Node{ID: uintID(5)}},
+				},
+			},
+			// Some of the dials complete but no new ones are launched yet because
+			// the sum of active dial count and dynamic peer count is == maxDynDials.
+			{
+				peers: []*Peer{
+					{rw: &conn{flags: staticDialedConn, id: uintID(0)}},
+					{rw: &conn{flags: dynDialedConn, id: uintID(1)}},
+					{rw: &conn{flags: dynDialedConn, id: uintID(2)}},
+					{rw: &conn{flags: dynDialedConn, id: uintID(3)}},
+					{rw: &conn{flags: dynDialedConn, id: uintID(4)}},
+				},
+				done: []task{
+					&dialTask{dynDialedConn, &discover.Node{ID: uintID(3)}},
+					&dialTask{dynDialedConn, &discover.Node{ID: uintID(4)}},
+				},
+			},
+			// No new dial tasks are launched in the this round because
+			// maxDynDials has been reached.
+			{
+				peers: []*Peer{
+					{rw: &conn{flags: staticDialedConn, id: uintID(0)}},
+					{rw: &conn{flags: dynDialedConn, id: uintID(1)}},
+					{rw: &conn{flags: dynDialedConn, id: uintID(2)}},
+					{rw: &conn{flags: dynDialedConn, id: uintID(3)}},
+					{rw: &conn{flags: dynDialedConn, id: uintID(4)}},
+					{rw: &conn{flags: dynDialedConn, id: uintID(5)}},
+				},
+				done: []task{
+					&dialTask{dynDialedConn, &discover.Node{ID: uintID(5)}},
+				},
+				new: []task{
+					&waitExpireTask{Duration: 14 * time.Second},
+				},
+			},
+			// In this round, the peer with id 2 drops off. The query
+			// results from last discovery lookup are reused.
+			{
+				peers: []*Peer{
+					{rw: &conn{flags: staticDialedConn, id: uintID(0)}},
+					{rw: &conn{flags: dynDialedConn, id: uintID(1)}},
+					{rw: &conn{flags: dynDialedConn, id: uintID(3)}},
+					{rw: &conn{flags: dynDialedConn, id: uintID(4)}},
+					{rw: &conn{flags: dynDialedConn, id: uintID(5)}},
+				},
+				new: []task{
+					&dialTask{dynDialedConn, &discover.Node{ID: uintID(6)}},
+				},
+			},
+			// More peers (3,4) drop off and dial for ID 6 completes.
+			// The last query result from the discovery lookup is reused
+			// and a new one is spawned because more candidates are needed.
+			{
+				peers: []*Peer{
+					{rw: &conn{flags: staticDialedConn, id: uintID(0)}},
+					{rw: &conn{flags: dynDialedConn, id: uintID(1)}},
+					{rw: &conn{flags: dynDialedConn, id: uintID(5)}},
+				},
+				done: []task{
+					&dialTask{dynDialedConn, &discover.Node{ID: uintID(6)}},
+				},
+				new: []task{
+					&dialTask{dynDialedConn, &discover.Node{ID: uintID(7)}},
+					&discoverTask{},
+				},
+			},
+			// Peer 7 is connected, but there still aren't enough dynamic peers
+			// (4 out of 5). However, a discovery is already running, so ensure
+			// no new is started.
+			{
+				peers: []*Peer{
+					{rw: &conn{flags: staticDialedConn, id: uintID(0)}},
+					{rw: &conn{flags: dynDialedConn, id: uintID(1)}},
+					{rw: &conn{flags: dynDialedConn, id: uintID(5)}},
+					{rw: &conn{flags: dynDialedConn, id: uintID(7)}},
+				},
+				done: []task{
+					&dialTask{dynDialedConn, &discover.Node{ID: uintID(7)}},
+				},
+			},
+			// Finish the running node discovery with an empty set. A new lookup
+			// should be immediately requested.
+			{
+				peers: []*Peer{
+					{rw: &conn{flags: staticDialedConn, id: uintID(0)}},
+					{rw: &conn{flags: dynDialedConn, id: uintID(1)}},
+					{rw: &conn{flags: dynDialedConn, id: uintID(5)}},
+					{rw: &conn{flags: dynDialedConn, id: uintID(7)}},
+				},
+				done: []task{
+					&discoverTask{},
+				},
+				new: []task{
+					&discoverTask{},
+				},
+			},
+		},
+	})
+}
+
+func TestDialStateDynDialFromTable(t *testing.T) {
+	// This table always returns the same random nodes
+	// in the order given below.
+	table := fakeTable{
+		{ID: uintID(1)},
+		{ID: uintID(2)},
+		{ID: uintID(3)},
+		{ID: uintID(4)},
+		{ID: uintID(5)},
+		{ID: uintID(6)},
+		{ID: uintID(7)},
+		{ID: uintID(8)},
+	}
+
+	runDialTest(t, dialtest{
+		init: newDialState(nil, table, 10),
+		rounds: []round{
+			// Discovery bootstrap is launched.
+			{
+				new: []task{&discoverTask{bootstrap: true}},
+			},
+			// 5 out of 8 of the nodes returned by ReadRandomNodes are dialed.
+			{
+				done: []task{
+					&discoverTask{bootstrap: true},
+				},
+				new: []task{
+					&dialTask{dynDialedConn, &discover.Node{ID: uintID(1)}},
+					&dialTask{dynDialedConn, &discover.Node{ID: uintID(2)}},
+					&dialTask{dynDialedConn, &discover.Node{ID: uintID(3)}},
+					&dialTask{dynDialedConn, &discover.Node{ID: uintID(4)}},
+					&dialTask{dynDialedConn, &discover.Node{ID: uintID(5)}},
+					&discoverTask{bootstrap: false},
+				},
+			},
+			// Dialing nodes 1,2 succeeds. Dials from the lookup are launched.
+			{
+				peers: []*Peer{
+					{rw: &conn{flags: dynDialedConn, id: uintID(1)}},
+					{rw: &conn{flags: dynDialedConn, id: uintID(2)}},
+				},
+				done: []task{
+					&dialTask{dynDialedConn, &discover.Node{ID: uintID(1)}},
+					&dialTask{dynDialedConn, &discover.Node{ID: uintID(2)}},
+					&discoverTask{results: []*discover.Node{
+						{ID: uintID(10)},
+						{ID: uintID(11)},
+						{ID: uintID(12)},
+					}},
+				},
+				new: []task{
+					&dialTask{dynDialedConn, &discover.Node{ID: uintID(10)}},
+					&dialTask{dynDialedConn, &discover.Node{ID: uintID(11)}},
+					&dialTask{dynDialedConn, &discover.Node{ID: uintID(12)}},
+					&discoverTask{bootstrap: false},
+				},
+			},
+			// Dialing nodes 3,4,5 fails. The dials from the lookup succeed.
+			{
+				peers: []*Peer{
+					{rw: &conn{flags: dynDialedConn, id: uintID(1)}},
+					{rw: &conn{flags: dynDialedConn, id: uintID(2)}},
+					{rw: &conn{flags: dynDialedConn, id: uintID(10)}},
+					{rw: &conn{flags: dynDialedConn, id: uintID(11)}},
+					{rw: &conn{flags: dynDialedConn, id: uintID(12)}},
+				},
+				done: []task{
+					&dialTask{dynDialedConn, &discover.Node{ID: uintID(3)}},
+					&dialTask{dynDialedConn, &discover.Node{ID: uintID(4)}},
+					&dialTask{dynDialedConn, &discover.Node{ID: uintID(5)}},
+					&dialTask{dynDialedConn, &discover.Node{ID: uintID(10)}},
+					&dialTask{dynDialedConn, &discover.Node{ID: uintID(11)}},
+					&dialTask{dynDialedConn, &discover.Node{ID: uintID(12)}},
+				},
+			},
+			// Waiting for expiry. No waitExpireTask is launched because the
+			// discovery query is still running.
+			{
+				peers: []*Peer{
+					{rw: &conn{flags: dynDialedConn, id: uintID(1)}},
+					{rw: &conn{flags: dynDialedConn, id: uintID(2)}},
+					{rw: &conn{flags: dynDialedConn, id: uintID(10)}},
+					{rw: &conn{flags: dynDialedConn, id: uintID(11)}},
+					{rw: &conn{flags: dynDialedConn, id: uintID(12)}},
+				},
+			},
+			// Nodes 3,4 are not tried again because only the first two
+			// returned random nodes (nodes 1,2) are tried and they're
+			// already connected.
+			{
+				peers: []*Peer{
+					{rw: &conn{flags: dynDialedConn, id: uintID(1)}},
+					{rw: &conn{flags: dynDialedConn, id: uintID(2)}},
+					{rw: &conn{flags: dynDialedConn, id: uintID(10)}},
+					{rw: &conn{flags: dynDialedConn, id: uintID(11)}},
+					{rw: &conn{flags: dynDialedConn, id: uintID(12)}},
+				},
+			},
+		},
+	})
+}
+
+// This test checks that static dials are launched.
+func TestDialStateStaticDial(t *testing.T) {
+	wantStatic := []*discover.Node{
+		{ID: uintID(1)},
+		{ID: uintID(2)},
+		{ID: uintID(3)},
+		{ID: uintID(4)},
+		{ID: uintID(5)},
+	}
+
+	runDialTest(t, dialtest{
+		init: newDialState(wantStatic, fakeTable{}, 0),
+		rounds: []round{
+			// Static dials are launched for the nodes that
+			// aren't yet connected.
+			{
+				peers: []*Peer{
+					{rw: &conn{flags: dynDialedConn, id: uintID(1)}},
+					{rw: &conn{flags: dynDialedConn, id: uintID(2)}},
+				},
+				new: []task{
+					&dialTask{staticDialedConn, &discover.Node{ID: uintID(3)}},
+					&dialTask{staticDialedConn, &discover.Node{ID: uintID(4)}},
+					&dialTask{staticDialedConn, &discover.Node{ID: uintID(5)}},
+				},
+			},
+			// No new tasks are launched in this round because all static
+			// nodes are either connected or still being dialed.
+			{
+				peers: []*Peer{
+					{rw: &conn{flags: dynDialedConn, id: uintID(1)}},
+					{rw: &conn{flags: dynDialedConn, id: uintID(2)}},
+					{rw: &conn{flags: staticDialedConn, id: uintID(3)}},
+				},
+				done: []task{
+					&dialTask{staticDialedConn, &discover.Node{ID: uintID(3)}},
+				},
+			},
+			// No new dial tasks are launched because all static
+			// nodes are now connected.
+			{
+				peers: []*Peer{
+					{rw: &conn{flags: dynDialedConn, id: uintID(1)}},
+					{rw: &conn{flags: dynDialedConn, id: uintID(2)}},
+					{rw: &conn{flags: staticDialedConn, id: uintID(3)}},
+					{rw: &conn{flags: staticDialedConn, id: uintID(4)}},
+					{rw: &conn{flags: staticDialedConn, id: uintID(5)}},
+				},
+				done: []task{
+					&dialTask{staticDialedConn, &discover.Node{ID: uintID(4)}},
+					&dialTask{staticDialedConn, &discover.Node{ID: uintID(5)}},
+				},
+				new: []task{
+					&waitExpireTask{Duration: 14 * time.Second},
+				},
+			},
+			// Wait a round for dial history to expire, no new tasks should spawn.
+			{
+				peers: []*Peer{
+					{rw: &conn{flags: dynDialedConn, id: uintID(1)}},
+					{rw: &conn{flags: dynDialedConn, id: uintID(2)}},
+					{rw: &conn{flags: staticDialedConn, id: uintID(3)}},
+					{rw: &conn{flags: staticDialedConn, id: uintID(4)}},
+					{rw: &conn{flags: staticDialedConn, id: uintID(5)}},
+				},
+			},
+			// If a static node is dropped, it should be immediately redialed,
+			// irrespective whether it was originally static or dynamic.
+			{
+				peers: []*Peer{
+					{rw: &conn{flags: dynDialedConn, id: uintID(1)}},
+					{rw: &conn{flags: staticDialedConn, id: uintID(3)}},
+					{rw: &conn{flags: staticDialedConn, id: uintID(5)}},
+				},
+				new: []task{
+					&dialTask{staticDialedConn, &discover.Node{ID: uintID(2)}},
+					&dialTask{staticDialedConn, &discover.Node{ID: uintID(4)}},
+				},
+			},
+		},
+	})
+}
+
+// This test checks that past dials are not retried for some time.
+func TestDialStateCache(t *testing.T) {
+	wantStatic := []*discover.Node{
+		{ID: uintID(1)},
+		{ID: uintID(2)},
+		{ID: uintID(3)},
+	}
+
+	runDialTest(t, dialtest{
+		init: newDialState(wantStatic, fakeTable{}, 0),
+		rounds: []round{
+			// Static dials are launched for the nodes that
+			// aren't yet connected.
+			{
+				peers: nil,
+				new: []task{
+					&dialTask{staticDialedConn, &discover.Node{ID: uintID(1)}},
+					&dialTask{staticDialedConn, &discover.Node{ID: uintID(2)}},
+					&dialTask{staticDialedConn, &discover.Node{ID: uintID(3)}},
+				},
+			},
+			// No new tasks are launched in this round because all static
+			// nodes are either connected or still being dialed.
+			{
+				peers: []*Peer{
+					{rw: &conn{flags: staticDialedConn, id: uintID(1)}},
+					{rw: &conn{flags: staticDialedConn, id: uintID(2)}},
+				},
+				done: []task{
+					&dialTask{staticDialedConn, &discover.Node{ID: uintID(1)}},
+					&dialTask{staticDialedConn, &discover.Node{ID: uintID(2)}},
+				},
+			},
+			// A salvage task is launched to wait for node 3's history
+			// entry to expire.
+			{
+				peers: []*Peer{
+					{rw: &conn{flags: dynDialedConn, id: uintID(1)}},
+					{rw: &conn{flags: dynDialedConn, id: uintID(2)}},
+				},
+				done: []task{
+					&dialTask{staticDialedConn, &discover.Node{ID: uintID(3)}},
+				},
+				new: []task{
+					&waitExpireTask{Duration: 14 * time.Second},
+				},
+			},
+			// Still waiting for node 3's entry to expire in the cache.
+			{
+				peers: []*Peer{
+					{rw: &conn{flags: dynDialedConn, id: uintID(1)}},
+					{rw: &conn{flags: dynDialedConn, id: uintID(2)}},
+				},
+			},
+			// The cache entry for node 3 has expired and is retried.
+			{
+				peers: []*Peer{
+					{rw: &conn{flags: dynDialedConn, id: uintID(1)}},
+					{rw: &conn{flags: dynDialedConn, id: uintID(2)}},
+				},
+				new: []task{
+					&dialTask{staticDialedConn, &discover.Node{ID: uintID(3)}},
+				},
+			},
+		},
+	})
+}
+
+// compares task lists but doesn't care about the order.
+func sametasks(a, b []task) bool {
+	if len(a) != len(b) {
+		return false
+	}
+next:
+	for _, ta := range a {
+		for _, tb := range b {
+			if reflect.DeepEqual(ta, tb) {
+				continue next
+			}
+		}
+		return false
+	}
+	return true
+}
+
+func uintID(i uint32) discover.NodeID {
+	var id discover.NodeID
+	binary.BigEndian.PutUint32(id[:], i)
+	return id
+}