dex: redesign p2p network topology

- Let p2p server support direct connection and group connection.
- Introduce node meta table to maintain IP of all nodes in node set,
  in memory and let nodes in the network can sync this table.
- Let peerSet able to manage direct connections to notary set and dkg set.

The mechanism to refresh the network topology when configuration round
change is not done yet.

1 files changed, 79 insertions, 0 deletions

diff --git a/dex/nodetable.go b/dex/nodetable.go
new file mode 100644
index 000000000..929b168a8
--- /dev/null
+++ b/dex/nodetable.go
@@ -0,0 +1,79 @@
+package dex
+
+import (
+	"net"
+	"sync"
+
+	"github.com/dexon-foundation/dexon/common"
+	"github.com/dexon-foundation/dexon/crypto/sha3"
+	"github.com/dexon-foundation/dexon/event"
+	"github.com/dexon-foundation/dexon/p2p/enode"
+	"github.com/dexon-foundation/dexon/rlp"
+)
+
+type NodeMeta struct {
+	ID        enode.ID
+	IP        net.IP
+	UDP       int
+	TCP       int
+	Timestamp uint64
+	Sig       []byte
+}
+
+func (n *NodeMeta) Hash() (h common.Hash) {
+	hw := sha3.NewKeccak256()
+	rlp.Encode(hw, n)
+	hw.Sum(h[:0])
+	return h
+}
+
+type newMetasEvent struct{ Metas []*NodeMeta }
+
+type nodeTable struct {
+	mu    sync.RWMutex
+	entry map[enode.ID]*NodeMeta
+	feed  event.Feed
+}
+
+func newNodeTable() *nodeTable {
+	return &nodeTable{
+		entry: make(map[enode.ID]*NodeMeta),
+	}
+}
+
+func (t *nodeTable) Get(id enode.ID) *NodeMeta {
+	t.mu.RLock()
+	defer t.mu.RUnlock()
+	return t.entry[id]
+}
+
+func (t *nodeTable) Add(metas []*NodeMeta) {
+	t.mu.Lock()
+	defer t.mu.Unlock()
+
+	var newMetas []*NodeMeta
+	for _, meta := range metas {
+		// TODO: validate the meta
+		if e, ok := t.entry[meta.ID]; ok && e.Timestamp > meta.Timestamp {
+			continue
+		}
+		t.entry[meta.ID] = meta
+		newMetas = append(newMetas, meta)
+	}
+	t.feed.Send(newMetasEvent{newMetas})
+}
+
+func (t *nodeTable) Metas() []*NodeMeta {
+	t.mu.RLock()
+	defer t.mu.RUnlock()
+	metas := make([]*NodeMeta, 0, len(t.entry))
+	for _, meta := range t.entry {
+		metas = append(metas, meta)
+	}
+	return metas
+}
+
+func (t *nodeTable) SubscribeNewMetasEvent(
+	ch chan<- newMetasEvent) event.Subscription {
+	return t.feed.Subscribe(ch)
+}