DappConfig.sol

Overview

DappConfig.sol defines the DappConfig contract, which serves as the configuration manager for an individual decentralized application (DApp). Its primary role is to store and manage credit configuration parameters, including balances and limits related to token usage within the DApp. The contract ensures secure updates to these configurations and handles incoming token transfers, adjusting balances accordingly. It enforces access control to sensitive operations, allowing only authorized entities to modify the configuration data.

Contract: DappConfig

Purpose

The DappConfig contract maintains the credit configuration state for a single DApp instance. It provides mechanisms for initializing the configuration, updating credit balances, managing authorized public keys, and processing incoming token transfers. This contract is designed to interact primarily with the DappRoot entity (as the deployer and owner) and internal system messages for secure updates.

State Variables

Variable	Type	Visibility	Description
`version`	`string constant`	internal	Contract version identifier ("1.0.0").
`_data`	`CreditConfig`	internal	Stores credit configuration data including balances and limits.
`_owner`	`address`	internal	Owner address, set to a fixed address expected to be `DappRoot`.
`_dapp_id`	`uint256`	internal	Unique identifier for the DApp instance.
`_authorityAddress`	`optional(address)`	public	Optional address authorized to append new public keys.
`_keys`	`uint256[]`	public	Dynamic array storing authorized public keys.

Constructor

constructor (
    uint256 dapp_id,
    CreditConfig data,
    optional(address) authorityAddress
)

Parameters:
- dapp_id: The unique identifier for the DApp, provided during deployment.
- data: Initial credit configuration, including balances and limits.
- authorityAddress: Optional address authorized to manage public keys.
Functionality:
- Extracts the dapp_id from the contract's code salt.
- Sets _owner to a fixed address (expected to be the DappRoot).
- Requires the deploying address to be _owner, enforcing deployment restrictions.
- Initializes _data with the supplied credit config.
- Sets _authorityAddress if provided.

Usage Example:

CreditConfig initialConfig = CreditConfig({ /* fields initialized */ });
optional(address) authority = someAuthorityAddress;
DappConfig config = new DappConfig(dappId, initialConfig, authority);

Requirements:
- Deployment transaction sender must be the DappRoot contract.

Methods

appendPubkey

function appendPubkey(uint256 pubkey) public senderIs(_authorityAddress.get()) accept

Purpose: Appends a new public key to the _keys array, allowing authorized entities to extend the list of recognized keys.
Parameters:
- pubkey: The public key to be appended.
Access Control: Only callable by the _authorityAddress.
Implementation Details:
- Checks if the maximum size of _keys (MAX_SIZE_OF_KEYS) is reached; if so, silently returns.
- Otherwise, appends the new pubkey.
Usage Example:
```
config.appendPubkey(newPubkey);
```

setNewConfig

function setNewConfig(int128 value) public internalMsg senderIs(address(this)) functionID(5)

Purpose: Updates the credit configuration by deducting a specified amount from the available balance.
Parameters:
- value: The amount to deduct (signed integer).
Access Control: Only callable internally by the contract itself (i.e., through an internal message).
Functionality: Decreases _data.available_balance by value.
Usage Context: Expected to be invoked by the internal system or block producer to reflect token minting or spending.

setNewUnlimit

function setNewUnlimit(bool is_unlimit) public internalMsg senderIs(address(this))

Purpose: Sets or clears the "unlimited" flag in the credit configuration.
Parameters:
- is_unlimit: Boolean flag indicating whether the credit is unlimited.
Access Control: Only callable internally by the contract itself.
Functionality: Updates _data.is_unlimit accordingly.

receive (Fallback function)

receive() external

Purpose: Handles incoming currency transfers to the contract.
Functionality:
- Accepts the incoming message.
- Adds the amount of ECC_SHELL currency received to _data.available_balance.
- Checks the contract's balance against a minimum threshold (MIN_BALANCE).
- If below minimum, triggers conversion of ECC_SHELL tokens to increase the balance.
- Burns surplus ECC_SHELL tokens beyond a defined threshold (BALANCE_ECC).
Implementation Details:
- Uses constants CURRENCIES_ID_SHELL, MIN_BALANCE, BALANCE_ECC.
- Performs conversions and burning via external calls to gosh.cnvrtshellq and gosh.burnecc.
Usage: Automatically invoked when the contract receives funds.

getDetails

function getDetails() external view returns(uint256 dapp_id, CreditConfig data)

Purpose: Provides read-only access to the DApp configuration details.
Returns:
- dapp_id: The unique DApp identifier.
- data: The current credit configuration structure.

Usage Example:

(uint256 id, CreditConfig configData) = config.getDetails();

Important Implementation Details

Access Control: Enforced via modifiers such as senderIs and internalMsg, ensuring that only authorized addresses or internal contract calls can modify sensitive state.
CreditConfig: A custom data structure (not defined within this file) that encapsulates credit-related data including balances and flags. Refer to the relevant CreditConfig topic for its definition.
Token Handling: The contract deals with ECC_SHELL currency tokens, managing their balance, conversion, and burning through interactions with an external gosh contract.
Owner Address: The _owner is set to a hardcoded address, expected to represent the DappRoot contract. This ensures that only the root can deploy DappConfig instances.
Public Key Management: Authorized keys for signature verification or authorization can be appended by an _authorityAddress. The maximum number of keys is capped by MAX_SIZE_OF_KEYS.

Interactions with Other System Components

DappRoot Contract: Only the DappRoot contract can deploy instances of DappConfig, enforcing a hierarchical relationship.
gosh Contract: The contract interacts with gosh for operations such as converting and burning ECC_SHELL tokens.
Modifiers Library: Inherits from Modifiers, which provides access control and other behavioral checks. See Modifiers for details.
DappLib Library: Imports DappLib.sol, although its functions are not explicitly invoked in the shown code. This may provide additional utilities related to DApp configuration or credit management.
CreditConfig Structure: This data structure is crucial for storing credit parameters and is manipulated throughout the contract. Its definition and usage are documented in CreditConfig.

Visual Diagram

classDiagram
class DappConfig {
-string version
-CreditConfig _data
-address _owner
-uint256 _dapp_id
-optional(address) _authorityAddress
-uint256[] _keys
+constructor(dapp_id, data, authorityAddress)
+appendPubkey()
+setNewConfig()
+setNewUnlimit()
+receive()
+getDetails()
}
DappConfig ..|> Modifiers

This class diagram highlights the main attributes and methods of the DappConfig contract, illustrating its role as a specialized configuration manager with secure update capabilities and token handling logic.