Airdrop Contracts

Key Features

• ERC20 Token Distribution: Supports airdropping any ERC20 token

• Merkle Proof Verification: Uses cryptographic proofs to verify claim eligibility

• Gas Efficient: Only stores one Merkle root instead of all user data

• Claim Tracking: Prevents double-claiming by maintaining a record of claimed addresses

• Owner Controls: Allows the owner to update the Merkle root and withdraw unclaimed tokens

GitHub - bio-xyz/airdrop-contractsGitHub

MerkleAirdrop Contract

A contract that implements a Merkle tree–based airdrop for ERC20 tokens with controlled claim processing and robust admin management.

Features

• Merkle Tree Eligibility:

  • Utilizes a stored Merkle root to verify if an address is eligible for the airdrop.

  • The inMerkle() function checks a user's address and claim amount against the Merkle proof.

• Claiming Process:

  • Users can claim tokens via the claim() function if they are eligible.

  • Prevents double claims by tracking claims in a mapping.

  • Emits a Claimed event on successful claims.

• Admin Controls:

  • The owner can update the Merkle root using the updateMerkleRoot() function.

  • Allows the owner to withdraw tokens from the contract with the withdraw() function.

Inheritance

• ReentrancyGuard: Provides protection against reentrancy attacks on critical functions.

• Ownable: Restricts sensitive functions to the contract owner.

Key Functions

• claim(uint256 amount, bytes32[] calldata proof): Allows eligible users to claim their tokens if their Merkle proof is valid.

• inMerkle(address who, uint256 amount, bytes32[] calldata proof): Verifies that the address and claim amount are part of the Merkle tree.

• hasClaimed(address who): Checks whether an address has already claimed the airdrop.

• updateMerkleRoot(bytes32 _root): Enables the owner to update the Merkle root to adjust eligibility.

• withdraw(address recipient, uint256 amount): Allows the owner to withdraw tokens from the contract if needed.

Security Features

• Reentrancy Protection: Critical functions (like claim()) are secured against reentrant calls.

• Safe Transfers: Utilizes the SafeERC20 library to ensure secure token transfers.

• Access Control: Owner-only functions safeguard administrative tasks such as updating the Merkle root and withdrawing tokens.