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Wraplock

Reference documentation for the wraplock contract.

The source for this contract can be obtained on its Github repository.

Overview​

This contract publishes user and administration interfaces for managing the locking and unlocking of native tokens on the source chain of the token bridge:

  • User actions: cancela, cancelb, withdrawa, withdrawb
  • Administrative actions: init, addcontract, delcontract, enable, disable
  • Inline action (for IBC Bridge to prove): emitxfer
  • Notifications: transfer

Structs​

STRUCT xfer​

Data structure used as an argument to the emitxfer action.

Fields

  • {name} owner - sender of the transfer
  • {extended_asset} quantity - object of the transfer
  • {name} beneficiary - receiver of the transfer

Tables​

TABLE contractmap​

This table contains the data records used for mapping between native token contracts and wrapped token contracts.

Fields

  • {name} native_token_contract - name of the native token contract
  • {name} paired_wraptoken_contract - name of the wrapped token contract

TABLE global​

This table contains a singleton entry with the global configuration parameters of this contract instance (see init).

Fields

  • {checksum256} chain_id - the chain ID of this chain
  • {name} bridge_contract - account where the IBC Bridge contract is deployed on this chain
  • {checksum256} paired_chain_id - the chain ID of the chain at the other end of this Wrap Lock / Token bridge
  • {bool} enabled - set to false if this contract is currently set to refuse all incoming requests

TABLE processed​

This table is used to hold action receipt digests of accepted proven actions, to prevent replay attacks.

Fields

  • {uint64_t} id - key for this action receipt digest
  • {checksum256} receipt_digest - hash of the action receipt that has already been accepted

TABLE reserves​

This table contains the reserve account balances (i.e. the deposited and locked tokens), scoped by the contract of the deposited token.

Fields

  • {asset} balance - a deposited (locked) token balance

Actions​

ACTION init​

Allows contract account to set which chains and associated bridge contracts are used for interchain transfers.

Authority

  • get_self()

Parameters

  • {checksum256} chain_id - the id of the chain running this contract
  • {name} bridge_contract - the bridge contract on this chain
  • {checksum256} paired_chain_id - the id of the chain hosting the wrapped tokens

ACTION addcontract​

Allows contract account to add support for an asset contract for interchain transfers.

Authority

  • get_self()

Parameters

  • {name} native_token_contract - the token contract being enabled for interchain transfers
  • {name} paired_wraptoken_contract - the corresponding wraptoken contract which transfers are sent to/from

ACTION delcontract​

Allows contract account to disable support for an asset contract for interchain transfers.

Authority

  • get_self()

Parameters

  • {name} native_token_contract - the token contract being disabled for interchain transfers

ACTION disable​

Disable all user actions on the contract.

Authority

  • get_self()

Parameters

None.

ACTION enable​

Enable all user actions on the contract.

Authority

  • get_self()

Parameters

None.

ACTION withdrawa​

Allows prover account to redeem native tokens and send them to the beneficiary indentified in the actionproof.

Authority

  • None.

Parameters

  • {name} prover - the calling account whose ram is used for storing the action receipt digest to prevent replay attacks
  • {bridge::heavyproof} blockproof - the heavy proof data structure
  • {bridge::actionproof} actionproof - the proof structure for the emitxfer action associated with the retire action on the wrapped tokens chain

ACTION withdrawb​

Allows prover account to redeem native tokens and send them to the beneficiary indentified in the actionproof.

Authority

  • prover

Parameters

  • {name} prover - the calling account whose ram is used for storing the action receipt digest to prevent replay attacks
  • {bridge::lightproof} blockproof - the light proof data structure
  • {bridge::actionproof} actionproof - the proof structure for the emitxfer action associated with the retire action on the wrapped tokens chain

ACTION cancela​

Allows prover account to cancel a token transfer and return them to the beneficiary indentified in the actionproof.

Authority

  • prover

Parameters

  • {name} prover - the calling account whose ram is used for storing the action receipt digest to prevent replay attacks
  • {bridge::heavyproof} blockproof - the heavy proof data structure
  • {bridge::actionproof} actionproof - the proof structure for the emitxfer action associated with the retiring transfer action on the native chain

ACTION cancelb​

Allows prover account to cancel a token transfer and return them to the beneficiary indentified in the actionproof.

Authority

  • prover

Parameters

  • {name} prover - the calling account whose ram is used for storing the action receipt digest to prevent replay attacks
  • {bridge::lightproof} blockproof - the light proof data structure
  • {bridge::actionproof} actionproof - the proof structure for the emitxfer action associated with the retiring transfer action on the native chain

ACTION emitxfer​

This is an action that is called inline by this contract when tokens are locked (by the transfer notification). Proof of this action is then used on the wrapped token chain.

Authority

  • get_self()

Parameters

  • {wraplock::xfer} xfer - struct that contains the parameters of the token lock

Notifications​

NOTIFICATION *::transfer​

On receiving a transfer notification from any contract (assuming the source contract conforms to the eosio.token interface), makes an internal deposit(from, to, quantity, memo) call (with the same, matching arguments from the transfer notification), which locks the quantity of tokens sent inside this contract's reserves table, and calls the emitxfer action inline so that can be used as the basis for a proof of locking for the issue or cancel actions on the wrapped token chain.

Parameters

  • {name} from - the owner of the tokens to be sent to the wrapped token chain
  • {name} to - this contract account
  • {asset} quantity - the asset to be sent to the wrapped token chain
  • {string} memo - the beneficiary account on the wrapped token chain