Keepers

The bank module provides these exported keeper interfaces that can be passed to other modules that read or update account balances. Modules should use the least-permissive interface that provides the functionality they require.

Best practices dictate careful review of bank module code to ensure that permissions are limited in the way that you expect.

Blocklisting Addresses

The x/bank module accepts a map of addresses that are considered blocklisted from directly and explicitly receiving funds through means such as MsgSend and MsgMultiSend and direct API calls like SendCoinsFromModuleToAccount.

Typically, these addresses are module accounts. If these addresses receive funds outside the expected rules of the state machine, invariants are likely to be broken and could result in a halted network.

By providing the x/bank module with a blocklisted set of addresses, an error occurs for the operation if a user or client attempts to directly or indirectly send funds to a blocklisted account, for example, by using IBC (opens new window).

Common Types

Input

An input of a multiparty transfer

Copy // Input models transaction input. message Input { string address = 1; repeated cosmos.base.v1beta1.Coin coins = 2; }

Output

An output of a multiparty transfer.

Copy // Output models transaction outputs. message Output { string address = 1; repeated cosmos.base.v1beta1.Coin coins = 2; }

BaseKeeper

The base keeper provides full-permission access: the ability to arbitrary modify any account's balance and mint or burn coins.

Restricted permission to mint per module could be achieved by using baseKeeper with WithMintCoinsRestriction to give specific restrictions to mint (e.g. only minting certain denom).

Copy // Keeper defines a module interface that facilitates the transfer of coins // between accounts. type Keeper interface { SendKeeper WithMintCoinsRestriction(NewRestrictionFn BankMintingRestrictionFn) BaseKeeper InitGenesis(sdk.Context, *types.GenesisState) ExportGenesis(sdk.Context) *types.GenesisState GetSupply(ctx sdk.Context, denom string) sdk.Coin GetPaginatedTotalSupply(ctx sdk.Context, pagination *query.PageRequest) (sdk.Coins, *query.PageResponse, error) IterateTotalSupply(ctx sdk.Context, cb func(sdk.Coin) bool) GetDenomMetaData(ctx sdk.Context, denom string) (types.Metadata, bool) SetDenomMetaData(ctx sdk.Context, denomMetaData types.Metadata) IterateAllDenomMetaData(ctx sdk.Context, cb func(types.Metadata) bool) SendCoinsFromModuleToAccount(ctx sdk.Context, senderModule string, recipientAddr sdk.AccAddress, amt sdk.Coins) error SendCoinsFromModuleToModule(ctx sdk.Context, senderModule, recipientModule string, amt sdk.Coins) error SendCoinsFromAccountToModule(ctx sdk.Context, senderAddr sdk.AccAddress, recipientModule string, amt sdk.Coins) error DelegateCoinsFromAccountToModule(ctx sdk.Context, senderAddr sdk.AccAddress, recipientModule string, amt sdk.Coins) error UndelegateCoinsFromModuleToAccount(ctx sdk.Context, senderModule string, recipientAddr sdk.AccAddress, amt sdk.Coins) error MintCoins(ctx sdk.Context, moduleName string, amt sdk.Coins) error BurnCoins(ctx sdk.Context, moduleName string, amt sdk.Coins) error DelegateCoins(ctx sdk.Context, delegatorAddr, moduleAccAddr sdk.AccAddress, amt sdk.Coins) error UndelegateCoins(ctx sdk.Context, moduleAccAddr, delegatorAddr sdk.AccAddress, amt sdk.Coins) error types.QueryServer }

SendKeeper

The send keeper provides access to account balances and the ability to transfer coins between accounts. The send keeper does not alter the total supply (mint or burn coins).

Copy // SendKeeper defines a module interface that facilitates the transfer of coins // between accounts without the possibility of creating coins. type SendKeeper interface { ViewKeeper InputOutputCoins(ctx sdk.Context, inputs []types.Input, outputs []types.Output) error SendCoins(ctx sdk.Context, fromAddr sdk.AccAddress, toAddr sdk.AccAddress, amt sdk.Coins) error GetParams(ctx sdk.Context) types.Params SetParams(ctx sdk.Context, params types.Params) IsSendEnabledCoin(ctx sdk.Context, coin sdk.Coin) bool IsSendEnabledCoins(ctx sdk.Context, coins ...sdk.Coin) error BlockedAddr(addr sdk.AccAddress) bool }

ViewKeeper

The view keeper provides read-only access to account balances. The view keeper does not have balance alteration functionality. All balance lookups are O(1).

Copy // ViewKeeper defines a module interface that facilitates read only access to // account balances. type ViewKeeper interface { ValidateBalance(ctx sdk.Context, addr sdk.AccAddress) error HasBalance(ctx sdk.Context, addr sdk.AccAddress, amt sdk.Coin) bool GetAllBalances(ctx sdk.Context, addr sdk.AccAddress) sdk.Coins GetAccountsBalances(ctx sdk.Context) []types.Balance GetBalance(ctx sdk.Context, addr sdk.AccAddress, denom string) sdk.Coin LockedCoins(ctx sdk.Context, addr sdk.AccAddress) sdk.Coins SpendableCoins(ctx sdk.Context, addr sdk.AccAddress) sdk.Coins IterateAccountBalances(ctx sdk.Context, addr sdk.AccAddress, cb func(coin sdk.Coin) (stop bool)) IterateAllBalances(ctx sdk.Context, cb func(address sdk.AccAddress, coin sdk.Coin) (stop bool)) }