The 'domain' is not recalculated in case of a hard fork

[code423n4]

Handle

pauliax

Vulnerability details

Impact

The variable domain in contract Swivel is cached in the contract storage and will not change after being initialized. However, if a hard fork happens after the contract deployment, the domain would become invalid on one of the forked chains due to the block.chainid has changed. A similar issue was reported in a previous contest and was assigned a severity of low: code-423n4/2021-06-realitycards-findings#166

Recommended Mitigation Steps

An elegant solution that you may consider applying is from Sushi Trident: https://github.com/sushiswap/trident/blob/concentrated/contracts/pool/concentrated/TridentNFT.sol#L47-L62