les: limit LES peer count and improve peer configuration logic (#16010)

* les: limit number of LES connections

* eth, cmd/utils: light vs max peer configuration logic

1 files changed, 23 insertions, 3 deletions

diff --git a/cmd/utils/flags.go b/cmd/utils/flags.go
index 58bb95243..833cd95de 100644
--- a/cmd/utils/flags.go
+++ b/cmd/utils/flags.go
@@ -179,7 +179,7 @@ var (
 	LightPeersFlag = cli.IntFlag{
 		Name:  "lightpeers",
 		Usage: "Maximum number of LES client peers",
-		Value: 20,
+		Value: eth.DefaultConfig.LightPeers,
 	}
 	LightKDFFlag = cli.BoolFlag{
 		Name:  "lightkdf",
@@ -791,20 +791,40 @@ func SetP2PConfig(ctx *cli.Context, cfg *p2p.Config) {
 	setBootstrapNodes(ctx, cfg)
 	setBootstrapNodesV5(ctx, cfg)
 
+	lightClient := ctx.GlobalBool(LightModeFlag.Name) || ctx.GlobalString(SyncModeFlag.Name) == "light"
+	lightServer := ctx.GlobalInt(LightServFlag.Name) != 0
+	lightPeers := ctx.GlobalInt(LightPeersFlag.Name)
+
 	if ctx.GlobalIsSet(MaxPeersFlag.Name) {
 		cfg.MaxPeers = ctx.GlobalInt(MaxPeersFlag.Name)
+	} else {
+		if lightServer {
+			cfg.MaxPeers += lightPeers
+		}
+		if lightClient && ctx.GlobalIsSet(LightPeersFlag.Name) && cfg.MaxPeers < lightPeers {
+			cfg.MaxPeers = lightPeers
+		}
 	}
+	if !(lightClient || lightServer) {
+		lightPeers = 0
+	}
+	ethPeers := cfg.MaxPeers - lightPeers
+	if lightClient {
+		ethPeers = 0
+	}
+	log.Info("Maximum peer count", "ETH", ethPeers, "LES", lightPeers, "total", cfg.MaxPeers)
+
 	if ctx.GlobalIsSet(MaxPendingPeersFlag.Name) {
 		cfg.MaxPendingPeers = ctx.GlobalInt(MaxPendingPeersFlag.Name)
 	}
-	if ctx.GlobalIsSet(NoDiscoverFlag.Name) || ctx.GlobalBool(LightModeFlag.Name) {
+	if ctx.GlobalIsSet(NoDiscoverFlag.Name) || lightClient {
 		cfg.NoDiscovery = true
 	}
 
 	// if we're running a light client or server, force enable the v5 peer discovery
 	// unless it is explicitly disabled with --nodiscover note that explicitly specifying
 	// --v5disc overrides --nodiscover, in which case the later only disables v4 discovery
-	forceV5Discovery := (ctx.GlobalBool(LightModeFlag.Name) || ctx.GlobalInt(LightServFlag.Name) > 0) && !ctx.GlobalBool(NoDiscoverFlag.Name)
+	forceV5Discovery := (lightClient || lightServer) && !ctx.GlobalBool(NoDiscoverFlag.Name)
 	if ctx.GlobalIsSet(DiscoveryV5Flag.Name) {
 		cfg.DiscoveryV5 = ctx.GlobalBool(DiscoveryV5Flag.Name)
 	} else if forceV5Discovery {