les: implement ultralight client (#16904)

For more information about this light client mode, read
https://hackmd.io/s/HJy7jjZpm

3 files changed, 60 insertions, 0 deletions

diff --git a/cmd/geth/config.go b/cmd/geth/config.go
index 62eeef701..f316380ce 100644
--- a/cmd/geth/config.go
+++ b/cmd/geth/config.go
@@ -125,6 +125,7 @@ func makeConfigNode(ctx *cli.Context) (*node.Node, gethConfig) {
 	}
 
 	// Apply flags.
+	utils.SetULC(ctx, &cfg.Eth)
 	utils.SetNodeConfig(ctx, &cfg.Node)
 	stack, err := node.New(&cfg.Node)
 	if err != nil {
diff --git a/cmd/geth/main.go b/cmd/geth/main.go
index fb5ec20eb..2be2bca95 100644
--- a/cmd/geth/main.go
+++ b/cmd/geth/main.go
@@ -82,6 +82,10 @@ var (
 		utils.TxPoolAccountQueueFlag,
 		utils.TxPoolGlobalQueueFlag,
 		utils.TxPoolLifetimeFlag,
+		utils.ULCModeConfigFlag,
+		utils.OnlyAnnounceModeFlag,
+		utils.ULCTrustedNodesFlag,
+		utils.ULCMinTrustedFractionFlag,
 		utils.SyncModeFlag,
 		utils.GCModeFlag,
 		utils.LightServFlag,
diff --git a/cmd/utils/flags.go b/cmd/utils/flags.go
index 33650685c..a80cdd6cd 100644
--- a/cmd/utils/flags.go
+++ b/cmd/utils/flags.go
@@ -19,6 +19,7 @@ package utils
 
 import (
 	"crypto/ecdsa"
+	"encoding/json"
 	"fmt"
 	"io/ioutil"
 	"math/big"
@@ -161,6 +162,23 @@ var (
 		Usage: "Document Root for HTTPClient file scheme",
 		Value: DirectoryString{homeDir()},
 	}
+	ULCModeConfigFlag = cli.StringFlag{
+		Name:  "ulc.config",
+		Usage: "Config file to use for ultra light client mode",
+	}
+	OnlyAnnounceModeFlag = cli.BoolFlag{
+		Name:  "ulc.onlyannounce",
+		Usage: "ULC server sends announcements only",
+	}
+	ULCMinTrustedFractionFlag = cli.IntFlag{
+		Name:  "ulc.fraction",
+		Usage: "Minimum % of trusted ULC servers required to announce a new head",
+	}
+	ULCTrustedNodesFlag = cli.StringFlag{
+		Name:  "ulc.trusted",
+		Usage: "List of trusted ULC servers",
+	}
+
 	defaultSyncMode = eth.DefaultConfig.SyncMode
 	SyncModeFlag    = TextMarshalerFlag{
 		Name:  "syncmode",
@@ -871,6 +889,40 @@ func setIPC(ctx *cli.Context, cfg *node.Config) {
 	}
 }
 
+// SetULC setup ULC config from file if given.
+func SetULC(ctx *cli.Context, cfg *eth.Config) {
+	// ULC config isn't loaded from global config and ULC config and ULC trusted nodes are not defined.
+	if cfg.ULC == nil && !(ctx.GlobalIsSet(ULCModeConfigFlag.Name) || ctx.GlobalIsSet(ULCTrustedNodesFlag.Name)) {
+		return
+	}
+	cfg.ULC = &eth.ULCConfig{}
+
+	path := ctx.GlobalString(ULCModeConfigFlag.Name)
+	if path != "" {
+		cfgData, err := ioutil.ReadFile(path)
+		if err != nil {
+			Fatalf("Failed to unmarshal ULC configuration: %v", err)
+		}
+
+		err = json.Unmarshal(cfgData, &cfg.ULC)
+		if err != nil {
+			Fatalf("Failed to unmarshal ULC configuration: %s", err.Error())
+		}
+	}
+
+	if trustedNodes := ctx.GlobalString(ULCTrustedNodesFlag.Name); trustedNodes != "" {
+		cfg.ULC.TrustedServers = strings.Split(trustedNodes, ",")
+	}
+
+	if trustedFraction := ctx.GlobalInt(ULCMinTrustedFractionFlag.Name); trustedFraction > 0 {
+		cfg.ULC.MinTrustedFraction = trustedFraction
+	}
+	if cfg.ULC.MinTrustedFraction <= 0 && cfg.ULC.MinTrustedFraction > 100 {
+		log.Error("MinTrustedFraction is invalid", "MinTrustedFraction", cfg.ULC.MinTrustedFraction, "Changed to default", eth.DefaultULCMinTrustedFraction)
+		cfg.ULC.MinTrustedFraction = eth.DefaultULCMinTrustedFraction
+	}
+}
+
 // makeDatabaseHandles raises out the number of allowed file handles per process
 // for Geth and returns half of the allowance to assign to the database.
 func makeDatabaseHandles() int {
@@ -1222,6 +1274,9 @@ func SetEthConfig(ctx *cli.Context, stack *node.Node, cfg *eth.Config) {
 	if ctx.GlobalIsSet(LightPeersFlag.Name) {
 		cfg.LightPeers = ctx.GlobalInt(LightPeersFlag.Name)
 	}
+	if ctx.GlobalIsSet(OnlyAnnounceModeFlag.Name) {
+		cfg.OnlyAnnounce = ctx.GlobalBool(OnlyAnnounceModeFlag.Name)
+	}
 	if ctx.GlobalIsSet(NetworkIdFlag.Name) {
 		cfg.NetworkId = ctx.GlobalUint64(NetworkIdFlag.Name)
 	}