cmd, eth, internal, les: add txfee cap (#21212)

* cmd, eth, internal, les: add gasprice cap

* cmd/utils, eth: add default value for gasprice cap

* all: use txfee cap

* cmd, eth: add fix

* cmd, internal: address comments

cmd/utils/flags.go

@@ -478,6 +478,11 @@ var (
 		Name:  "rpc.gascap",
 		Usage: "Sets a cap on gas that can be used in eth_call/estimateGas",
 	}
+	RPCGlobalTxFeeCap = cli.Float64Flag{
+		Name:  "rpc.txfeecap",
+		Usage: "Sets a cap on transaction fee (in ether) that can be sent via the RPC APIs (0 = no cap)",
+		Value: eth.DefaultConfig.RPCTxFeeCap,
+	}
 	// Logging and debug settings
 	EthStatsURLFlag = cli.StringFlag{
 		Name:  "ethstats",
@@ -1560,6 +1565,9 @@ func SetEthConfig(ctx *cli.Context, stack *node.Node, cfg *eth.Config) {
 	if ctx.GlobalIsSet(RPCGlobalGasCap.Name) {
 		cfg.RPCGasCap = new(big.Int).SetUint64(ctx.GlobalUint64(RPCGlobalGasCap.Name))
 	}
+	if ctx.GlobalIsSet(RPCGlobalTxFeeCap.Name) {
+		cfg.RPCTxFeeCap = ctx.GlobalFloat64(RPCGlobalTxFeeCap.Name)
+	}
 	if ctx.GlobalIsSet(DNSDiscoveryFlag.Name) {
 		urls := ctx.GlobalString(DNSDiscoveryFlag.Name)
 		if urls == "" {