add a discovery module to handle peer discovery

this package abstract the communication between node and beacon chain

Signed-off-by: Leo Chen <leo@harmony.one>

discovery/discovery.go

@@ -0,0 +1,62 @@
+package discovery
+
+import (
+	"fmt"
+
+	"github.com/dedis/kyber"
+	"github.com/harmony-one/harmony/p2p"
+)
+
+type ConfigEntry struct {
+	IP          string
+	Port        string
+	Role        string
+	ShardID     string
+	ValidatorID int // Validator ID in its shard.
+	leader      p2p.Peer
+	self        p2p.Peer
+	peers       []p2p.Peer
+	pubK        kyber.Scalar
+	priK        kyber.Point
+}
+
+func (config ConfigEntry) String() string {
+	return fmt.Sprintf("idc: %v:%v", config.IP, config.Port)
+}
+
+func New(pubK kyber.Scalar, priK kyber.Point) *ConfigEntry {
+	var config ConfigEntry
+	config.pubK = pubK
+	config.priK = priK
+
+	config.peers = make([]p2p.Peer, 0)
+
+	return &config
+}
+
+func (config *ConfigEntry) StartClientMode(idcIP, idcPort string) error {
+	config.IP = "myip"
+	config.Port = "myport"
+
+	fmt.Printf("idc ip/port: %v/%v\n", idcIP, idcPort)
+
+	// ...
+	// TODO: connect to idc, and wait unless acknowledge
+	return nil
+}
+
+func (config *ConfigEntry) GetShardID() string {
+	return config.ShardID
+}
+
+func (config *ConfigEntry) GetPeers() []p2p.Peer {
+	return config.peers
+}
+
+func (config *ConfigEntry) GetLeader() p2p.Peer {
+	return config.leader
+}
+
+func (config *ConfigEntry) GetSelfPeer() p2p.Peer {
+	return config.self
+}