NewtonSanctionsHook

A signed trades hook. It uses an outside price feed, needs signed approvals and controls who adds or removes liquidity.

• Uses an outside price feed

  It reads a price from an outside source (an oracle) and uses it in its rules.

  The code that does this (lookup):

  function _lookup(address[] memory who, bool enforceAge) internal view returns (bool[] memory flags) {
      uint256 updated = sanctionsOracle.getLastUpdateBlockTimestamp();
      // RedStone records the timestamp of the block that updated the list, so a later one is a bad answer
      if (updated > block.timestamp) revert OracleAnswerMalformed();
      if (enforceAge && block.timestamp - updated > maxListAge) {
          revert SanctionsListStale(block.timestamp - updated, maxListAge);
      }
      flags = sanctionsOracle.areSanctioned(who);
      if (flags.length != who.length) revert OracleAnswerMalformed();
  }

• Needs a signed approval

  Some actions need a message signed by an approved address.

  The code that does this (checkIntent):

  function _checkIntent(
      NewtonMessage.Intent memory intent,
      bytes memory intentSignature,
      address actor,
      bytes memory expectedData,
      bytes32 expectedSignatureHash
  ) internal view {
      if (intent.from != actor) revert ActorMismatch(actor, intent.from);
      if (intent.to != actor) revert SubjectMismatch(actor, intent.to);
      if (intent.value != 0) revert IntentValueNotZero(intent.value);
      if (intent.chainId != block.chainid) revert IntentChainMismatch(intent.chainId);
      if (keccak256(intent.functionSignature) != expectedSignatureHash) revert IntentSignatureMismatch();
      if (keccak256(intent.data) != keccak256(expectedData)) revert IntentActionMismatch();
      if (!SignatureChecker.isValidSignatureNow(intent.from, _intentDigest(intent), intentSignature)) {
          revert IntentSignatureInvalid();
      }
  }

• Rules for adding or removing liquidity

  It decides who can add or remove liquidity, or when.

  The code that does this (beforeAddLiquidity):

  function beforeAddLiquidity(
      address sender,
      PoolKey calldata key,
      IPoolManager.ModifyLiquidityParams calldata params,
      bytes calldata hookData
  ) external onlyPoolManager returns (bytes4) {
      _authorize(
          sender,
          key,
          Action.AddLiquidity,
          HookIntent.addLiquidityData(key, params),
          keccak256(bytes(HookIntent.ADD_LIQUIDITY_SIGNATURE)),
          hookData
      );
      return IHooks.beforeAddLiquidity.selector;
  }

• Only approved callers create pools

  New pools with this hook can only be created by approved callers, for example its own factory or launcher.

  The code that does this (beforeInitialize):

  function beforeInitialize(address, PoolKey calldata key, uint160 sqrtPriceX96)
      external
      view
      onlyPoolManager
      returns (bytes4)
  {
      PoolId id = key.toId();
      if (!poolAllowed[id]) revert PoolNotAllowed(id);
      if (sqrtPriceX96 != openingPrice[id]) revert WrongOpeningPrice(sqrtPriceX96, openingPrice[id]);
      return IHooks.beforeInitialize.selector;
  }

• No trading before the start

  Trades are refused until trading has been opened.

  The code that does this (beforeSwap):

  function beforeSwap(address sender, PoolKey calldata key, IPoolManager.SwapParams calldata, bytes calldata)
      external
      view
      onlyPoolManager
      returns (bytes4, BeforeSwapDelta, uint24)
  {
      PoolId id = key.toId();
      if (!tradingOpen[id]) revert TradingClosed(id);
      _screenOnchain(sender, true);
      return (IHooks.beforeSwap.selector, BeforeSwapDeltaLibrary.ZERO_DELTA, 0);
  }

Who controls it: The hook developer can change which routers are trusted. The hook developer can also change: trading, max list age. The hook developer can also call: allow pool, open exit window, close exit window, transfer hook admin, cancel hook admin transfer. The code cannot be changed.

Based on the hook’s published code.