min commission rate check on create validator (#11)

add MustUpdateValidatorCommission

x/staking/keeper/msg_server.go

@@ -74,6 +74,11 @@ func (k msgServer) CreateValidator(goCtx context.Context, msg *types.MsgCreateVa
 	if err != nil {
 		return nil, err
 	}
+
+	if msg.Commission.Rate.LT(k.MinCommissionRate(ctx)) {
+		return nil, sdkerrors.Wrapf(types.ErrCommissionLTMinRate, "cannot set validator commission to less than minimum rate of %s", k.MinCommissionRate(ctx))
+	}
+
 	commission := types.NewCommissionWithTime(
 		msg.Commission.Rate, msg.Commission.MaxRate,
 		msg.Commission.MaxChangeRate, ctx.BlockHeader().Time,

x/staking/keeper/msg_server_test.go

@@ -0,0 +1,42 @@
+package keeper_test
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+	tmproto "github.com/tendermint/tendermint/proto/tendermint/types"
+
+	"github.com/cosmos/cosmos-sdk/simapp"
+	sdk "github.com/cosmos/cosmos-sdk/types"
+	"github.com/cosmos/cosmos-sdk/x/staking"
+	stakingtypes "github.com/cosmos/cosmos-sdk/x/staking/types"
+)
+
+func TestCreateValidatorWithLessThanMinCommission(t *testing.T) {
+	PKS := simapp.CreateTestPubKeys(1)
+	valConsPk1 := PKS[0]
+
+	app := simapp.Setup(false)
+	ctx := app.BaseApp.NewContext(false, tmproto.Header{})
+
+	addrs := simapp.AddTestAddrs(app, ctx, 3, sdk.NewInt(1234))
+
+	// set min commission rate to non-zero
+	params := app.StakingKeeper.GetParams(ctx)
+	params.MinCommissionRate = sdk.NewDecWithPrec(1, 2)
+	app.StakingKeeper.SetParams(ctx, params)
+
+	// create validator with 0% commission
+	msg, err := stakingtypes.NewMsgCreateValidator(
+		sdk.ValAddress(addrs[0]),
+		valConsPk1,
+		sdk.NewInt64Coin(sdk.DefaultBondDenom, 100),
+		stakingtypes.Description{},
+		stakingtypes.NewCommissionRates(sdk.NewDec(0), sdk.NewDecWithPrec(5, 1), sdk.NewDec(0)),
+		sdk.OneInt())
+	require.NoError(t, err)
+
+	sh := staking.NewHandler(app.StakingKeeper)
+	_, err = sh(ctx, msg)
+	require.Error(t, err)
+}

x/staking/keeper/validator.go

@@ -148,6 +148,23 @@ func (k Keeper) UpdateValidatorCommission(ctx sdk.Context,
 	return commission, nil
 }
 
+// MustUpdateValidatorCommission updates a validator's commission rate,
+// ignoring the max change rate.
+func (k Keeper) MustUpdateValidatorCommission(ctx sdk.Context,
+	validator types.Validator, newRate sdk.Dec) (types.Commission, error) {
+	commission := validator.Commission
+	blockTime := ctx.BlockHeader().Time
+
+	if newRate.LT(k.MinCommissionRate(ctx)) {
+		return commission, fmt.Errorf("cannot set validator commission to less than minimum rate of %s", k.MinCommissionRate(ctx))
+	}
+
+	commission.Rate = newRate
+	commission.UpdateTime = blockTime
+
+	return commission, nil
+}
+
 // remove the validator record and associated indexes
 // except for the bonded validator index which is only handled in ApplyAndReturnTendermintUpdates
 // TODO, this function panics, and it's not good.

x/staking/types/errors.go

@@ -49,4 +49,5 @@ var (
 	ErrInvalidHistoricalInfo           = sdkerrors.Register(ModuleName, 37, "invalid historical info")
 	ErrNoHistoricalInfo                = sdkerrors.Register(ModuleName, 38, "no historical info found")
 	ErrEmptyValidatorPubKey            = sdkerrors.Register(ModuleName, 39, "empty validator public key")
+	ErrCommissionLTMinRate             = sdkerrors.Register(ModuleName, 40, "commission cannot be less than min rate")
 )