handler.go

package bank

import (
	metrics "github.com/armon/go-metrics"

	"github.com/cosmos/cosmos-sdk/telemetry"
	sdk "github.com/cosmos/cosmos-sdk/types"
	sdkerrors "github.com/cosmos/cosmos-sdk/types/errors"
	"github.com/cosmos/cosmos-sdk/x/bank/keeper"
	"github.com/cosmos/cosmos-sdk/x/bank/types"
)

// NewHandler returns a handler for "bank" type messages.
func NewHandler(k keeper.Keeper) sdk.Handler {
	return func(ctx sdk.Context, msg sdk.Msg) (*sdk.Result, error) {
		ctx = ctx.WithEventManager(sdk.NewEventManager())

		switch msg := msg.(type) {
		case *types.MsgSend:
			return handleMsgSend(ctx, k, msg)

		case *types.MsgMultiSend:
			return handleMsgMultiSend(ctx, k, msg)

		default:
			return nil, sdkerrors.Wrapf(sdkerrors.ErrUnknownRequest, "unrecognized bank message type: %T", msg)
		}
	}
}

// Handle MsgSend.
func handleMsgSend(ctx sdk.Context, k keeper.Keeper, msg *types.MsgSend) (*sdk.Result, error) {
	if err := k.SendEnabledCoins(ctx, msg.Amount...); err != nil {
		return nil, err
	}

	from, err := sdk.AccAddressFromBech32(msg.FromAddress)
	if err != nil {
		return nil, err
	}
	to, err := sdk.AccAddressFromBech32(msg.ToAddress)
	if err != nil {
		return nil, err
	}

	if k.BlockedAddr(to) {
		return nil, sdkerrors.Wrapf(sdkerrors.ErrUnauthorized, "%s is not allowed to receive funds", msg.ToAddress)
	}

	err = k.SendCoins(ctx, from, to, msg.Amount)
	if err != nil {
		return nil, err
	}

	defer func() {
		for _, a := range msg.Amount {
			telemetry.SetGaugeWithLabels(
				[]string{"tx", "msg", "send"},
				float32(a.Amount.Int64()),
				[]metrics.Label{telemetry.NewLabel("denom", a.Denom)},
			)
		}
	}()

	ctx.EventManager().EmitEvent(
		sdk.NewEvent(
			sdk.EventTypeMessage,
			sdk.NewAttribute(sdk.AttributeKeyModule, types.AttributeValueCategory),
		),
	)

	return &sdk.Result{Events: ctx.EventManager().ABCIEvents()}, nil
}

// Handle MsgMultiSend.
func handleMsgMultiSend(ctx sdk.Context, k keeper.Keeper, msg *types.MsgMultiSend) (*sdk.Result, error) {
	// NOTE: totalIn == totalOut should already have been checked
	for _, in := range msg.Inputs {
		if err := k.SendEnabledCoins(ctx, in.Coins...); err != nil {
			return nil, err
		}
	}

	for _, out := range msg.Outputs {
		accAddr, err := sdk.AccAddressFromBech32(out.Address)
		if err != nil {
			panic(err)
		}
		if k.BlockedAddr(accAddr) {
			return nil, sdkerrors.Wrapf(sdkerrors.ErrUnauthorized, "%s is not allowed to receive transactions", out.Address)
		}
	}

	err := k.InputOutputCoins(ctx, msg.Inputs, msg.Outputs)
	if err != nil {
		return nil, err
	}

	ctx.EventManager().EmitEvent(
		sdk.NewEvent(
			sdk.EventTypeMessage,
			sdk.NewAttribute(sdk.AttributeKeyModule, types.AttributeValueCategory),
		),
	)

	return &sdk.Result{Events: ctx.EventManager().ABCIEvents()}, nil
}