InvestorVesting

Git Source

Overview

The InvestorVesting contract implements a linear token vesting schedule for investors participating in the Lendefi DAO ecosystem. Derived from OpenZeppelin's VestingWallet, this contract provides a clean, gas-efficient mechanism for token distribution with time-based release controls.

Architecture Analysis

Contract Structure

• Inheritance Model: Implements IVESTING interface and inherits from Context and Ownable2Step

• Storage Design: Uses immutable variables for core parameters (token, start, duration)

• Release Mechanism: On-demand release pattern rather than automatic distribution

• Ownership Model: Two-step ownership transfer for improved security

Vesting Design

• Schedule Type: Pure linear vesting with no cliff period

• Calculation Method: Uses time proportion formula: totalAllocation * (currentTime - startTime) / duration

• Flexibility: Relies on manual release calls rather than automatic distribution

Technical Assessment

Strengths

1. Gas Efficiency:

   • Immutable variables reduce storage operations

   • On-demand release pattern conserves gas

   • Efficient vesting calculation with minimal operations

2. Security Features:

   • Two-step ownership transfers prevent accidental transfers

   • SafeERC20 usage protects against non-standard token implementations

   • Input validation for zero addresses

   • Precise timestamp handling with SafeCast

3. Clean Design:

   • Single-responsibility principle followed throughout

   • Clear separation between calculation and execution

   • Minimal storage footprint

4. Auditability:

   • Simple, straightforward implementation

   • Well-documented functions with comments

   • Clear naming conventions

Potential Concerns

1. Limited Flexibility:

   • No cliff period option for investors

   • No partial release functionality

   • No way to adjust vesting parameters after deployment

2. Transfer Restrictions:

   • Beneficiary (owner) cannot transfer partial rights to another address

   • No streaming of tokens (only discrete releases)

3. Technical Considerations:

   • Mapping for _erc20Released seems unnecessary since only one token is used

   • No recovery mechanism for accidentally sent tokens

   • No events for constructor initialization

4. Edge Cases:

   • No handling for token rebasing or fee-on-transfer tokens

   • Function may fail if token implements hooks that consume excessive gas

Code Quality Assessment

• Documentation: Good NatSpec documentation for functions

• Input Validation: Basic zero address check in constructor

• Event Emissions: Appropriate event for token release

• Variable Naming: Clear and descriptive

• Code Organization: Logical grouping of functions

• Inheritance: Appropriate use of OpenZeppelin contracts

Inherits: IVESTING, Context, Ownable2Step

Investor Vesting contract

Offers flexible withdrawal schedule (gas efficient)

Implements linear vesting schedule for investors

Note: security-contact: [e-mail]

State Variables

_start

start timestamp

uint64 private immutable _start;

_duration

duration seconds

uint64 private immutable _duration;

_token

token address

address private immutable _token;

_erc20Released

amount of tokens released

mapping(address token => uint256 amount) private _erc20Released;

Functions

constructor

Sets the owner to beneficiary address, the start timestamp and the vesting duration of the vesting contract.

constructor(address token, address beneficiary, uint64 startTimestamp, uint64 durationSeconds) Ownable(beneficiary);

release

Release the tokens that have already vested. Emits a {ERC20Released} event.

function release() public virtual;

start

Getter for the start timestamp.

function start() public view virtual returns (uint256);

Returns

Name	Type	Description
<none>	uint256	start timestamp

duration

Getter for the vesting duration.

function duration() public view virtual returns (uint256);

Returns

Name	Type	Description
<none>	uint256	duration seconds

end

Getter for the end timestamp.

function end() public view virtual returns (uint256);

Returns

Name	Type	Description
<none>	uint256	end timnestamp

released

Getter for the amount of token already released

function released() public view virtual returns (uint256);

Returns

Name	Type	Description
<none>	uint256	amount of tokens released so far

releasable

Getter for the amount of vested ERC20 tokens.

function releasable() public view virtual returns (uint256);

Returns

Name	Type	Description
<none>	uint256	amount of vested tokens

vestedAmount

Calculates the amount of tokens that has already vested. Default implementation is a linear vesting curve.

function vestedAmount(uint64 timestamp) internal view virtual returns (uint256);

Parameters

Name	Type	Description
timestamp	uint64	current timestamp

Returns

Name	Type	Description
<none>	uint256	amount vested

_vestingSchedule

Virtual implementation of the vesting formula. This returns the amount vested, as a function of time, for an asset given its total historical allocation.

function _vestingSchedule(uint256 totalAllocation, uint64 timestamp) internal view virtual returns (uint256);

Parameters

Name	Type	Description
totalAllocation	uint256	initial amount
timestamp	uint64	current timestamp

Returns

Name	Type	Description
<none>	uint256	amount vested