feat(protocol): implement releaseEther & releaseERC20 (#13008)

Co-authored-by: David <david@taiko.xyz> Co-authored-by: jeff <113397187+cyberhorsey@users.noreply.github.com>
taikoxyz · Jan 25, 2023 · 088933e · 088933e
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diff --git a/packages/protocol/CHANGELOG.md b/packages/protocol/CHANGELOG.md
@@ -2,43 +2,41 @@
 
 ## [0.1.0](https://github.com/taikoxyz/taiko-mono/compare/protocol-v0.0.1...protocol-v0.1.0) (2023-01-19)
 
-
 ### Features
 
-* **bridge:** add getMessageStatusSlot function ([#12940](https://github.com/taikoxyz/taiko-mono/issues/12940)) ([9837fa3](https://github.com/taikoxyz/taiko-mono/commit/9837fa3dceb5d702b2247879af52988be4da333d))
-* **bridge:** bridge transactions ([#411](https://github.com/taikoxyz/taiko-mono/issues/411)) ([19dd7ab](https://github.com/taikoxyz/taiko-mono/commit/19dd7abd4a2f5bc83e43d31938e43501472ff108))
-* **bridge:** implement the bridge relayer ([#191](https://github.com/taikoxyz/taiko-mono/issues/191)) ([9f49e4c](https://github.com/taikoxyz/taiko-mono/commit/9f49e4c87304853c9d94693434d23a6b8258eac6))
-* **deployment:** fund L1 bridge ([#400](https://github.com/taikoxyz/taiko-mono/issues/400)) ([e7ef53e](https://github.com/taikoxyz/taiko-mono/commit/e7ef53e27cb906d7128a3e512e7082e4176786e4))
-* **docs:** autocommit changes to solidity docs and omit private state vars and functions ([#490](https://github.com/taikoxyz/taiko-mono/issues/490)) ([dbf8db9](https://github.com/taikoxyz/taiko-mono/commit/dbf8db97635e4fa7c1808c55e62c20f5e987935d))
-* **genesis:** support deterministic L2 pre-deployed contract addresses ([#358](https://github.com/taikoxyz/taiko-mono/issues/358)) ([cd34f17](https://github.com/taikoxyz/taiko-mono/commit/cd34f17382400f0ee3bfa85c8ef6a1f5acdb749a))
-* migrate to nextra ([#12947](https://github.com/taikoxyz/taiko-mono/issues/12947)) ([ac11959](https://github.com/taikoxyz/taiko-mono/commit/ac1195940d1ab450e95367e6008162de1d22f0ab))
-* **protocol:** add `TaikoL1.getBlockProvers` ([#340](https://github.com/taikoxyz/taiko-mono/issues/340)) ([c54f810](https://github.com/taikoxyz/taiko-mono/commit/c54f810d3251f97fcc1e061478044b93bfc0cf28))
-* **protocol:** allow empty L2 blocks  ([#406](https://github.com/taikoxyz/taiko-mono/issues/406)) ([6d1abf7](https://github.com/taikoxyz/taiko-mono/commit/6d1abf7bd8565bf0377a42b823a6ad98959c340a))
-* **protocol:** allow whitelisting proposers ([#375](https://github.com/taikoxyz/taiko-mono/issues/375)) ([80b99a4](https://github.com/taikoxyz/taiko-mono/commit/80b99a4afe6f68f9bca6d7b07e584e57c2ea7f0b))
-* **protocol:** enhance ZKP handling & change proofs order ([#288](https://github.com/taikoxyz/taiko-mono/issues/288)) ([5fdfdfa](https://github.com/taikoxyz/taiko-mono/commit/5fdfdfad4207792411f5e92dcee5c603dbeaeee3))
-* **protocol:** expose getUncleProofDelay function ([#7058](https://github.com/taikoxyz/taiko-mono/issues/7058)) ([dd0f011](https://github.com/taikoxyz/taiko-mono/commit/dd0f01179ab328d0d8ebb20a07204df821b36a77))
-* **protocol:** implement & simulate tokenomics ([#376](https://github.com/taikoxyz/taiko-mono/issues/376)) ([191eb11](https://github.com/taikoxyz/taiko-mono/commit/191eb110990d60b49883eb3f3d7841c33421d067))
-* **protocol:** invalidBlock must from golden touch address with 0 gasprice ([#482](https://github.com/taikoxyz/taiko-mono/issues/482)) ([ecb9cc5](https://github.com/taikoxyz/taiko-mono/commit/ecb9cc543513e61ae9efbdfb17cacda87ce3f70d))
-* **protocol:** preprocess variables for test ([#445](https://github.com/taikoxyz/taiko-mono/issues/445)) ([31584b4](https://github.com/taikoxyz/taiko-mono/commit/31584b47c11749711dcb3c61dc74581991141de3))
-* **protocol:** whitelist provers & temporarily disable coverage check ([#296](https://github.com/taikoxyz/taiko-mono/issues/296)) ([06ceee2](https://github.com/taikoxyz/taiko-mono/commit/06ceee2599d01802683cca6b57e3fb6710946cd1))
-* **ui:** Template / initial repo for UI ([#304](https://github.com/taikoxyz/taiko-mono/issues/304)) ([a396511](https://github.com/taikoxyz/taiko-mono/commit/a39651133d4c3bd8b6eea5db93daec7698600707))
-
+- **bridge:** add getMessageStatusSlot function ([#12940](https://github.com/taikoxyz/taiko-mono/issues/12940)) ([9837fa3](https://github.com/taikoxyz/taiko-mono/commit/9837fa3dceb5d702b2247879af52988be4da333d))
+- **bridge:** bridge transactions ([#411](https://github.com/taikoxyz/taiko-mono/issues/411)) ([19dd7ab](https://github.com/taikoxyz/taiko-mono/commit/19dd7abd4a2f5bc83e43d31938e43501472ff108))
+- **bridge:** implement the bridge relayer ([#191](https://github.com/taikoxyz/taiko-mono/issues/191)) ([9f49e4c](https://github.com/taikoxyz/taiko-mono/commit/9f49e4c87304853c9d94693434d23a6b8258eac6))
+- **deployment:** fund L1 bridge ([#400](https://github.com/taikoxyz/taiko-mono/issues/400)) ([e7ef53e](https://github.com/taikoxyz/taiko-mono/commit/e7ef53e27cb906d7128a3e512e7082e4176786e4))
+- **docs:** autocommit changes to solidity docs and omit private state vars and functions ([#490](https://github.com/taikoxyz/taiko-mono/issues/490)) ([dbf8db9](https://github.com/taikoxyz/taiko-mono/commit/dbf8db97635e4fa7c1808c55e62c20f5e987935d))
+- **genesis:** support deterministic L2 pre-deployed contract addresses ([#358](https://github.com/taikoxyz/taiko-mono/issues/358)) ([cd34f17](https://github.com/taikoxyz/taiko-mono/commit/cd34f17382400f0ee3bfa85c8ef6a1f5acdb749a))
+- migrate to nextra ([#12947](https://github.com/taikoxyz/taiko-mono/issues/12947)) ([ac11959](https://github.com/taikoxyz/taiko-mono/commit/ac1195940d1ab450e95367e6008162de1d22f0ab))
+- **protocol:** add `TaikoL1.getBlockProvers` ([#340](https://github.com/taikoxyz/taiko-mono/issues/340)) ([c54f810](https://github.com/taikoxyz/taiko-mono/commit/c54f810d3251f97fcc1e061478044b93bfc0cf28))
+- **protocol:** allow empty L2 blocks ([#406](https://github.com/taikoxyz/taiko-mono/issues/406)) ([6d1abf7](https://github.com/taikoxyz/taiko-mono/commit/6d1abf7bd8565bf0377a42b823a6ad98959c340a))
+- **protocol:** allow whitelisting proposers ([#375](https://github.com/taikoxyz/taiko-mono/issues/375)) ([80b99a4](https://github.com/taikoxyz/taiko-mono/commit/80b99a4afe6f68f9bca6d7b07e584e57c2ea7f0b))
+- **protocol:** enhance ZKP handling & change proofs order ([#288](https://github.com/taikoxyz/taiko-mono/issues/288)) ([5fdfdfa](https://github.com/taikoxyz/taiko-mono/commit/5fdfdfad4207792411f5e92dcee5c603dbeaeee3))
+- **protocol:** expose getUncleProofDelay function ([#7058](https://github.com/taikoxyz/taiko-mono/issues/7058)) ([dd0f011](https://github.com/taikoxyz/taiko-mono/commit/dd0f01179ab328d0d8ebb20a07204df821b36a77))
+- **protocol:** implement & simulate tokenomics ([#376](https://github.com/taikoxyz/taiko-mono/issues/376)) ([191eb11](https://github.com/taikoxyz/taiko-mono/commit/191eb110990d60b49883eb3f3d7841c33421d067))
+- **protocol:** invalidBlock must from golden touch address with 0 gasprice ([#482](https://github.com/taikoxyz/taiko-mono/issues/482)) ([ecb9cc5](https://github.com/taikoxyz/taiko-mono/commit/ecb9cc543513e61ae9efbdfb17cacda87ce3f70d))
+- **protocol:** preprocess variables for test ([#445](https://github.com/taikoxyz/taiko-mono/issues/445)) ([31584b4](https://github.com/taikoxyz/taiko-mono/commit/31584b47c11749711dcb3c61dc74581991141de3))
+- **protocol:** whitelist provers & temporarily disable coverage check ([#296](https://github.com/taikoxyz/taiko-mono/issues/296)) ([06ceee2](https://github.com/taikoxyz/taiko-mono/commit/06ceee2599d01802683cca6b57e3fb6710946cd1))
+- **ui:** Template / initial repo for UI ([#304](https://github.com/taikoxyz/taiko-mono/issues/304)) ([a396511](https://github.com/taikoxyz/taiko-mono/commit/a39651133d4c3bd8b6eea5db93daec7698600707))
 
 ### Bug Fixes
 
-* **bridge:** Token Vault sendEther messages with processing fees are impossible to send ([#277](https://github.com/taikoxyz/taiko-mono/issues/277)) ([10d9bbc](https://github.com/taikoxyz/taiko-mono/commit/10d9bbc63ca624cc80c729942301eac334c960df))
-* **pnpm:** conflict with eslint command and use pnpm instead of npm ([#273](https://github.com/taikoxyz/taiko-mono/issues/273)) ([134cd5a](https://github.com/taikoxyz/taiko-mono/commit/134cd5a75fcf3e78feac5762985d09658404735e))
-* **preprocess:** fix hardhat preprocessor configs ([#368](https://github.com/taikoxyz/taiko-mono/issues/368)) ([8bdbb3e](https://github.com/taikoxyz/taiko-mono/commit/8bdbb3e3f5f30d11e4f9213690db316f2148568c))
-* **protocol:** Add EtherTransferred event to EtherVault [#12971](https://github.com/taikoxyz/taiko-mono/issues/12971) ([5791f3a](https://github.com/taikoxyz/taiko-mono/commit/5791f3af85df462cc5aabbdf2b14d957d49c9f00))
-* **protocol:** fix `BlockVerified` event ([#381](https://github.com/taikoxyz/taiko-mono/issues/381)) ([fe479c8](https://github.com/taikoxyz/taiko-mono/commit/fe479c8ff22b0da59ec75cc9e0dea04e38ebbb92))
-* **protocol:** fix `TokenVault.sendERC20` ([#420](https://github.com/taikoxyz/taiko-mono/issues/420)) ([d42b953](https://github.com/taikoxyz/taiko-mono/commit/d42b953c51e66948d7a6563042f7a521ee2d557a))
-* **protocol:** fix an occantional error in `test:tokenomics` ([#12950](https://github.com/taikoxyz/taiko-mono/issues/12950)) ([005364c](https://github.com/taikoxyz/taiko-mono/commit/005364c11c327f6dcaad7872c5064eb81e52f35b))
-* **protocol:** Fix bug in getProposedBlock ([#11679](https://github.com/taikoxyz/taiko-mono/issues/11679)) ([a6a596c](https://github.com/taikoxyz/taiko-mono/commit/a6a596cf10ecfa517a781e8c487b2d74f05a9526))
-* **protocol:** let `LibZKP.verify` return `true` ([#12676](https://github.com/taikoxyz/taiko-mono/issues/12676)) ([d0f17a6](https://github.com/taikoxyz/taiko-mono/commit/d0f17a6dc8921df49a63831d91170a7c11476bd9))
-* **protocol:** Remove enableDestChain functionality ([#12341](https://github.com/taikoxyz/taiko-mono/issues/12341)) ([362d083](https://github.com/taikoxyz/taiko-mono/commit/362d083497cc74b3bcd05a406beeff2101a422ef))
-* **protocol:** update avg proof time and avg block time ([#391](https://github.com/taikoxyz/taiko-mono/issues/391)) ([3681483](https://github.com/taikoxyz/taiko-mono/commit/3681483efe97c38a488563594c003dabfa23b2de))
-* **test:** fix the occasional `noNetwork` error in integration tests ([#7562](https://github.com/taikoxyz/taiko-mono/issues/7562)) ([a8e82d5](https://github.com/taikoxyz/taiko-mono/commit/a8e82d5c2d65d293d17953ff357816483eb25e00))
-* **test:** fix two occasional errors when running bridge tests ([#305](https://github.com/taikoxyz/taiko-mono/issues/305)) ([fb91e0d](https://github.com/taikoxyz/taiko-mono/commit/fb91e0d482df9a510e582dcf267aadd8892fcebd))
-* **test:** Fixed integration test case  ([#483](https://github.com/taikoxyz/taiko-mono/issues/483)) ([4b0893e](https://github.com/taikoxyz/taiko-mono/commit/4b0893e3b0a723cd9115fd0c03e4ec4d1e0d1a38))
-* **test:** making tests type-safe  ([#318](https://github.com/taikoxyz/taiko-mono/issues/318)) ([66ec7cc](https://github.com/taikoxyz/taiko-mono/commit/66ec7cc143af58dda8fde0d6adc30a4758685d1e))
-* **tests:** cleanup tests to prepare for tokenomics testing ([#11316](https://github.com/taikoxyz/taiko-mono/issues/11316)) ([d63fae3](https://github.com/taikoxyz/taiko-mono/commit/d63fae30f1e3415d6f377adeab90c062fed5ad42))
+- **bridge:** Token Vault sendEther messages with processing fees are impossible to send ([#277](https://github.com/taikoxyz/taiko-mono/issues/277)) ([10d9bbc](https://github.com/taikoxyz/taiko-mono/commit/10d9bbc63ca624cc80c729942301eac334c960df))
+- **pnpm:** conflict with eslint command and use pnpm instead of npm ([#273](https://github.com/taikoxyz/taiko-mono/issues/273)) ([134cd5a](https://github.com/taikoxyz/taiko-mono/commit/134cd5a75fcf3e78feac5762985d09658404735e))
+- **preprocess:** fix hardhat preprocessor configs ([#368](https://github.com/taikoxyz/taiko-mono/issues/368)) ([8bdbb3e](https://github.com/taikoxyz/taiko-mono/commit/8bdbb3e3f5f30d11e4f9213690db316f2148568c))
+- **protocol:** Add EtherTransferred event to EtherVault [#12971](https://github.com/taikoxyz/taiko-mono/issues/12971) ([5791f3a](https://github.com/taikoxyz/taiko-mono/commit/5791f3af85df462cc5aabbdf2b14d957d49c9f00))
+- **protocol:** fix `BlockVerified` event ([#381](https://github.com/taikoxyz/taiko-mono/issues/381)) ([fe479c8](https://github.com/taikoxyz/taiko-mono/commit/fe479c8ff22b0da59ec75cc9e0dea04e38ebbb92))
+- **protocol:** fix `TokenVault.sendERC20` ([#420](https://github.com/taikoxyz/taiko-mono/issues/420)) ([d42b953](https://github.com/taikoxyz/taiko-mono/commit/d42b953c51e66948d7a6563042f7a521ee2d557a))
+- **protocol:** fix an occantional error in `test:tokenomics` ([#12950](https://github.com/taikoxyz/taiko-mono/issues/12950)) ([005364c](https://github.com/taikoxyz/taiko-mono/commit/005364c11c327f6dcaad7872c5064eb81e52f35b))
+- **protocol:** Fix bug in getProposedBlock ([#11679](https://github.com/taikoxyz/taiko-mono/issues/11679)) ([a6a596c](https://github.com/taikoxyz/taiko-mono/commit/a6a596cf10ecfa517a781e8c487b2d74f05a9526))
+- **protocol:** let `LibZKP.verify` return `true` ([#12676](https://github.com/taikoxyz/taiko-mono/issues/12676)) ([d0f17a6](https://github.com/taikoxyz/taiko-mono/commit/d0f17a6dc8921df49a63831d91170a7c11476bd9))
+- **protocol:** Remove enableDestChain functionality ([#12341](https://github.com/taikoxyz/taiko-mono/issues/12341)) ([362d083](https://github.com/taikoxyz/taiko-mono/commit/362d083497cc74b3bcd05a406beeff2101a422ef))
+- **protocol:** update avg proof time and avg block time ([#391](https://github.com/taikoxyz/taiko-mono/issues/391)) ([3681483](https://github.com/taikoxyz/taiko-mono/commit/3681483efe97c38a488563594c003dabfa23b2de))
+- **test:** fix the occasional `noNetwork` error in integration tests ([#7562](https://github.com/taikoxyz/taiko-mono/issues/7562)) ([a8e82d5](https://github.com/taikoxyz/taiko-mono/commit/a8e82d5c2d65d293d17953ff357816483eb25e00))
+- **test:** fix two occasional errors when running bridge tests ([#305](https://github.com/taikoxyz/taiko-mono/issues/305)) ([fb91e0d](https://github.com/taikoxyz/taiko-mono/commit/fb91e0d482df9a510e582dcf267aadd8892fcebd))
+- **test:** Fixed integration test case ([#483](https://github.com/taikoxyz/taiko-mono/issues/483)) ([4b0893e](https://github.com/taikoxyz/taiko-mono/commit/4b0893e3b0a723cd9115fd0c03e4ec4d1e0d1a38))
+- **test:** making tests type-safe ([#318](https://github.com/taikoxyz/taiko-mono/issues/318)) ([66ec7cc](https://github.com/taikoxyz/taiko-mono/commit/66ec7cc143af58dda8fde0d6adc30a4758685d1e))
+- **tests:** cleanup tests to prepare for tokenomics testing ([#11316](https://github.com/taikoxyz/taiko-mono/issues/11316)) ([d63fae3](https://github.com/taikoxyz/taiko-mono/commit/d63fae30f1e3415d6f377adeab90c062fed5ad42))
diff --git a/packages/protocol/contracts/bridge/Bridge.sol b/packages/protocol/contracts/bridge/Bridge.sol
@@ -10,6 +10,7 @@ import "../common/EssentialContract.sol";
 import "./IBridge.sol";
 import "./libs/LibBridgeData.sol";
 import "./libs/LibBridgeProcess.sol";
+import "./libs/LibBridgeRelease.sol";
 import "./libs/LibBridgeRetry.sol";
 import "./libs/LibBridgeSend.sol";
 import "./libs/LibBridgeStatus.sol";
@@ -65,6 +66,19 @@ contract Bridge is EssentialContract, IBridge {
             });
     }
 
+    function releaseEther(
+        IBridge.Message calldata message,
+        bytes calldata proof
+    ) external nonReentrant {
+        return
+            LibBridgeRelease.releaseEther({
+                state: state,
+                resolver: AddressResolver(this),
+                message: message,
+                proof: proof
+            });
+    }
+
     function processMessage(
         Message calldata message,
         bytes calldata proof
@@ -142,7 +156,9 @@ contract Bridge is EssentialContract, IBridge {
             LibBridgeSend.isDestChainEnabled(AddressResolver(this), _chainId);
     }
 
-    function hashMessage(Message memory message) public pure returns (bytes32) {
+    function hashMessage(
+        Message calldata message
+    ) public pure override returns (bytes32) {
         return LibBridgeData.hashMessage(message);
     }
 

diff --git a/packages/protocol/contracts/bridge/EtherVault.sol b/packages/protocol/contracts/bridge/EtherVault.sol
@@ -33,7 +33,7 @@ contract EtherVault is EssentialContract {
 
     event Authorized(address indexed addr, bool authorized);
 
-    event EtherTransferred(address indexed to, uint256 amount);
+    event EtherReleased(address indexed to, uint256 amount);
 
     /*********************
      * Modifiers         *
@@ -65,12 +65,28 @@ contract EtherVault is EssentialContract {
      *********************/
 
     /**
-     * Send Ether from EtherVault to the sender, checking they are authorized.
+     * Transfer Ether from EtherVault to the sender, checking that the sender
+     * is authorized.
      * @param amount Amount of ether to send.
      */
-    function receiveEther(uint256 amount) public onlyAuthorized nonReentrant {
+    function releaseEther(uint256 amount) public onlyAuthorized nonReentrant {
         msg.sender.sendEther(amount);
-        emit EtherTransferred(msg.sender, amount);
+        emit EtherReleased(msg.sender, amount);
+    }
+
+    /**
+     * Transfer Ether from EtherVault to an desinated address, checking that the
+     * sender is authorized.
+     * @param recipient Address to receive Ether
+     * @param amount Amount of ether to send.
+     */
+    function releaseEtherTo(
+        address recipient,
+        uint256 amount
+    ) public onlyAuthorized nonReentrant {
+        require(recipient != address(0), "EV:recipient");
+        recipient.sendEther(amount);
+        emit EtherReleased(recipient, amount);
     }
 
     /**

diff --git a/packages/protocol/contracts/bridge/IBridge.sol b/packages/protocol/contracts/bridge/IBridge.sol
@@ -35,15 +35,22 @@ interface IBridge {
     }
 
     event SignalSent(address sender, bytes32 msgHash);
-
     event MessageSent(bytes32 indexed msgHash, Message message);
+    event EtherReleased(bytes32 indexed msgHash, address to, uint256 amount);
 
     /// Sends a message to the destination chain and takes custody
     /// of Ether required in this contract. All extra Ether will be refunded.
     function sendMessage(
         Message memory message
     ) external payable returns (bytes32 msgHash);
 
+    // Release Ether with a proof that the message processing on the destination
+    // chain has been failed.
+    function releaseEther(
+        IBridge.Message calldata message,
+        bytes calldata proof
+    ) external;
+
     /// Checks if a msgHash has been stored on the bridge contract by the
     /// current address.
     function isMessageSent(bytes32 msgHash) external view returns (bool);
@@ -65,4 +72,8 @@ interface IBridge {
 
     /// Returns the bridge state context.
     function context() external view returns (Context memory context);
+
+    function hashMessage(
+        IBridge.Message calldata message
+    ) external pure returns (bytes32);
 }