From 79c74c482becd72cf97d5ceb8e333474c200cb28 Mon Sep 17 00:00:00 2001
From: Constantine Bitensky
 <85228836+constantineatdaglabs@users.noreply.github.com>
Date: Tue, 8 Jun 2021 17:42:13 +0300
Subject: [PATCH] Get connections from Seeder when no connections left (#1742)

Co-authored-by: Constantine Bitensky <constantinebitensky@gmail.com>
---
 app/component_manager.go                      | 21 ----------------
 .../network/connmanager/connmanager.go        | 24 +++++++++++++++++++
 2 files changed, 24 insertions(+), 21 deletions(-)

diff --git a/app/component_manager.go b/app/component_manager.go
index 7e2d09de5..7cce2f2d2 100644
--- a/app/component_manager.go
+++ b/app/component_manager.go
@@ -4,7 +4,6 @@ import (
 	"fmt"
 	"sync/atomic"
 
-	"github.com/kaspanet/kaspad/app/appmessage"
 	"github.com/kaspanet/kaspad/app/protocol"
 	"github.com/kaspanet/kaspad/app/rpc"
 	"github.com/kaspanet/kaspad/domain"
@@ -14,7 +13,6 @@ import (
 	infrastructuredatabase "github.com/kaspanet/kaspad/infrastructure/db/database"
 	"github.com/kaspanet/kaspad/infrastructure/network/addressmanager"
 	"github.com/kaspanet/kaspad/infrastructure/network/connmanager"
-	"github.com/kaspanet/kaspad/infrastructure/network/dnsseed"
 	"github.com/kaspanet/kaspad/infrastructure/network/netadapter"
 	"github.com/kaspanet/kaspad/infrastructure/network/netadapter/id"
 	"github.com/kaspanet/kaspad/util/panics"
@@ -46,8 +44,6 @@ func (a *ComponentManager) Start() {
 		panics.Exit(log, fmt.Sprintf("Error starting the net adapter: %+v", err))
 	}
 
-	a.maybeSeedFromDNS()
-
 	a.connectionManager.Start()
 }
 
@@ -157,23 +153,6 @@ func setupRPC(
 	return rpcManager
 }
 
-func (a *ComponentManager) maybeSeedFromDNS() {
-	if !a.cfg.DisableDNSSeed {
-		dnsseed.SeedFromDNS(a.cfg.NetParams(), a.cfg.DNSSeed, false, nil,
-			a.cfg.Lookup, func(addresses []*appmessage.NetAddress) {
-				// Kaspad uses a lookup of the dns seeder here. Since seeder returns
-				// IPs of nodes and not its own IP, we can not know real IP of
-				// source. So we'll take first returned address as source.
-				a.addressManager.AddAddresses(addresses...)
-			})
-
-		dnsseed.SeedFromGRPC(a.cfg.NetParams(), a.cfg.GRPCSeed, false, nil,
-			func(addresses []*appmessage.NetAddress) {
-				a.addressManager.AddAddresses(addresses...)
-			})
-	}
-}
-
 // P2PNodeID returns the network ID associated with this ComponentManager
 func (a *ComponentManager) P2PNodeID() *id.ID {
 	return a.netAdapter.ID()
diff --git a/infrastructure/network/connmanager/connmanager.go b/infrastructure/network/connmanager/connmanager.go
index ab68e48c6..31b91069f 100644
--- a/infrastructure/network/connmanager/connmanager.go
+++ b/infrastructure/network/connmanager/connmanager.go
@@ -2,6 +2,7 @@ package connmanager
 
 import (
 	"github.com/kaspanet/kaspad/app/appmessage"
+	"github.com/kaspanet/kaspad/infrastructure/network/dnsseed"
 	"github.com/pkg/errors"
 	"net"
 	"sync"
@@ -104,6 +105,7 @@ func (c *ConnectionManager) initiateConnection(address string) error {
 const connectionsLoopInterval = 30 * time.Second
 
 func (c *ConnectionManager) connectionsLoop() {
+
 	for atomic.LoadUint32(&c.stop) == 0 {
 		connections := c.netAdapter.P2PConnections()
 
@@ -119,6 +121,8 @@ func (c *ConnectionManager) connectionsLoop() {
 
 		c.checkIncomingConnections(connSet)
 
+		c.seedFromDNS()
+
 		c.waitTillNextIteration()
 	}
 }
@@ -247,3 +251,23 @@ func (c *ConnectionManager) extractAddressIPs(address string) ([]net.IP, error)
 
 	return []net.IP{ip}, nil
 }
+
+func (c *ConnectionManager) seedFromDNS() {
+	cfg := c.cfg
+	if len(c.activeOutgoing) == 0 && !cfg.DisableDNSSeed {
+		log.Infof("No ongoing connections, trying to get new addresses from seed...")
+
+		dnsseed.SeedFromDNS(cfg.NetParams(), cfg.DNSSeed, false, nil,
+			cfg.Lookup, func(addresses []*appmessage.NetAddress) {
+				// Kaspad uses a lookup of the dns seeder here. Since seeder returns
+				// IPs of nodes and not its own IP, we can not know real IP of
+				// source. So we'll take first returned address as source.
+				_ = c.addressManager.AddAddresses(addresses...)
+			})
+
+		dnsseed.SeedFromGRPC(cfg.NetParams(), cfg.GRPCSeed, false, nil,
+			func(addresses []*appmessage.NetAddress) {
+				_ = c.addressManager.AddAddresses(addresses...)
+			})
+	}
+}