p2p: add back disable dht option (#5111)

## Motivation
p2p option disable-dht was removed by mistake

CHANGELOG.md

@@ -19,8 +19,8 @@ expected to be ~1.5 GiB.
 A new config `poet-request-timeout` has been added, that defines the timeout for requesting PoET proofs.
 It defaults to 9 minutes so there is enough time to retry if the request fails.
 
-Config option and flag `p2p-disable-legacy-discovery` and `disable-dht` have been dropped. DHT has been the
-only p2p discovery mechanism since release v1.1.2.
+Config option and flag `p2p-disable-legacy-discovery` is dropped. DHT has been the only p2p discovery
+mechanism since release v1.1.2.
 
 Support for old certificate sync protocol is dropped. This update is incompatible with v1.0.x series.
 

p2p/README.md

@@ -57,7 +57,7 @@ for them if needed.
 
 ### Configuration for private node
 
-Set min-peers to the number of peers in the config.
+Set min-peers to the number of peers in the config and disable-dht.
 low-peers and high-peers should not be lower than min-peers.
 
 ```json
@@ -67,6 +67,7 @@ low-peers and high-peers should not be lower than min-peers.
         "min-peers": 1,
         "low-peers": 10,
         "high-peers": 20,
+        "disable-dht": true,
         "bootnodes": [],
         "direct": [
             "/ip4/0.0.0.0/tcp/7513/p2p/12D3KooWRfy4Sj4rDHDuBaYw3Mg5d2puwiCyqBCWMziFquaGQ5g8"

p2p/dhtdiscovery/discovery.go

@@ -84,6 +84,12 @@ func WithDir(path string) Opt {
 	}
 }
 
+func DisableDHT() Opt {
+	return func(d *Discovery) {
+		d.disableDht = true
+	}
+}
+
 func New(h host.Host, opts ...Opt) (*Discovery, error) {
 	ctx, cancel := context.WithCancel(context.Background())
 	d := Discovery{
@@ -104,17 +110,20 @@ func New(h host.Host, opts ...Opt) (*Discovery, error) {
 	if len(d.bootnodes) == 0 {
 		d.logger.Warn("no bootnodes in the config")
 	}
-	err := d.newDht(ctx, h, d.public, d.server, d.dir)
-	if err != nil {
-		return nil, err
+	if !d.disableDht {
+		err := d.newDht(ctx, h, d.public, d.server, d.dir)
+		if err != nil {
+			return nil, err
+		}
 	}
 	return &d, nil
 }
 
 type Discovery struct {
-	public bool
-	server bool
-	dir    string
+	public     bool
+	server     bool
+	disableDht bool
+	dir        string
 
 	logger *zap.Logger
 	eg     errgroup.Group
@@ -180,11 +189,13 @@ func (d *Discovery) Start() {
 func (d *Discovery) Stop() {
 	d.cancel()
 	d.eg.Wait()
-	if err := d.dht.Close(); err != nil {
-		d.logger.Error("error closing dht", zap.Error(err))
-	}
-	if err := d.datastore.Close(); err != nil {
-		d.logger.Error("error closing level datastore", zap.Error(err))
+	if !d.disableDht {
+		if err := d.dht.Close(); err != nil {
+			d.logger.Error("error closing dht", zap.Error(err))
+		}
+		if err := d.datastore.Close(); err != nil {
+			d.logger.Error("error closing level datastore", zap.Error(err))
+		}
 	}
 }
 

p2p/host.go

@@ -83,6 +83,7 @@ type Config struct {
 	DisableNatPort           bool        `mapstructure:"disable-natport"`
 	DisableConnectionManager bool        `mapstructure:"disable-connection-manager"`
 	DisableResourceManager   bool        `mapstructure:"disable-resource-manager"`
+	DisableDHT               bool        `mapstructure:"disable-dht"`
 	Flood                    bool        `mapstructure:"flood"`
 	Listen                   string      `mapstructure:"listen"`
 	Bootnodes                []string    `mapstructure:"bootnodes"`

p2p/upgrade.go

@@ -132,6 +132,9 @@ func Upgrade(h host.Host, opts ...Opt) (*Host, error) {
 	if cfg.PrivateNetwork {
 		dopts = append(dopts, discovery.Private())
 	}
+	if cfg.DisableDHT {
+		dopts = append(dopts, discovery.DisableDHT())
+	}
 	if cfg.Bootnode {
 		dopts = append(dopts, discovery.Server())
 	} else {