multi token sessionkey validator [WIP]

[kanthgithub]

MultiToken SessionKey Validator Module

Description

• MultiTokenSessionKeyValidator Module is an advanced version of ERC20SessionKeyValidator
• Validator Module contains multiple ERC20 tokens with a cumulative-spending Limit in USD
• An erc7579 MultiToken SessionKey Module, which will allow a user to deploy a session key with the following constraints.
  1. select a list of assets.
  2. choose a cumulative spending limit. The cumulative spending limit must be compared to USD

Key features:

1. allowedList of Tokens

   • Tokens allowed to be validated on the Validator

   • Tokens are initialised during deployment of SessionKeyValidator

   • OraclePriceProvider addresses should be configured for all tokens during contract constructor

   • After the Validator is deployed, AllowedList of tokens can be added/removed by owner

   • Any new tokens added to the validator should also include the OracleProviderAddress

         function addAllowedTokens(address[] memory _tokens, address[] memory _priceFeeds) external onlyOwner {
         _addAllowedTokens(_tokens, _priceFeeds);
     }
     
     function _addAllowedTokens(address[] memory _tokens, address[] memory _priceFeeds) internal {
         for (uint256 i = 0; i < _tokens.length; i++) {
             allowedTokens.add(_tokens[i]);
             priceFeeds[_tokens[i]] = IAggregatorV3Interface(_priceFeeds[i]);
         }
     }

   • OracleProviderAddress for a specific token can be updated via updatePriceFeeds

         function updatePriceFeeds(address[] memory _tokens, address[] memory _priceFeeds) external onlyOwner {
         _updatePriceFeeds(_tokens, _priceFeeds);
     }
     
     function _updatePriceFeeds(address[] memory _tokens, address[] memory _priceFeeds) internal {
         for (uint256 i = 0; i < _tokens.length; i++) {
             priceFeeds[_tokens[i]] = IAggregatorV3Interface(_priceFeeds[i]);
         }
     }

2. CumulativeSpendingLimit (USD)

   • Spending limit in USD-Value of all tokens in the Validator
   • Limit is used to verify the total tokens spent via this validator for a sessionKey
   • SpendingLimit is managed in storage mapping for each sessionKey (sessionKey -> cumulativeSpendingLimit)
   • check on SpendingLimit is done on each validateUserOp / validateSessionKeyParams call

3. Oracle Price Query

       function getTokenPriceInUsd(address token) internal view returns (uint256) {
   
           (, int256 price, ,uint256 updatedAt, ) = priceFeeds[token].latestRoundData();
   
           if(price == 0) {
               revert MTSKV_InvalidTokenPrice(token);
           }
   
           if(block.timestamp - updatedAt >= stalenessThresholdInSeconds) {
               revert MTSKV_StaleTokenPrice(token);
           }
   
           return uint256(price);
       }

4. CumulativeSpendingLimit in USD estimation

          function estimateTotalSpentAmountInUsd(
     address sessionKey,
     address token,
     uint256 amount
   ) public view returns (uint256) {
     (uint256 tokenPriceUSD, uint8 feedDecimals) = getTokenPriceInUsd(token);
   
     uint8 tokenDecimals = IERC20(token).decimals();
     uint256 scaledAmount;
   
     if (tokenDecimals < USD_AMOUNT_DECIMALS) {
         // If token has fewer than 18 decimals, scale the amount up to 18 decimals
         scaledAmount = amount * (10 ** (USD_AMOUNT_DECIMALS - tokenDecimals));
     } else if(tokenDecimals > USD_AMOUNT_DECIMALS) {
         // If token has more than 18 decimals, scale the amount down to 18 decimals
         scaledAmount = amount / (10 ** (tokenDecimals - USD_AMOUNT_DECIMALS));            
     } else {
         scaledAmount = amount;
     }
   
     uint256 amountInUsd = (scaledAmount * tokenPriceUSD) / (10 ** feedDecimals);
   
     // add the amountInUsd with the totalSpentInUsd for the session key
     return amountInUsd + totalSpentInUsd[sessionKey];
   }
   
       function checkSpendingLimit(address sessionKey, address user, address token, uint256 amount) public view returns (bool) {
           MultiTokenSessionData memory data = multiTokenSessionData[sessionKey][user];
           return estimateTotalSpentAmountInUsd(sessionKey, token, amount) <= data.cumulativeSpendingLimitInUsd;
       }

How Has This Been Tested?

Types of changes

• New feature (non-breaking change which adds functionality)