imp!: improved client interfaces

src/ICS02Client.sol

@@ -6,15 +6,19 @@ import { Strings } from "@openzeppelin/contracts/utils/Strings.sol";
 import { IBCIdentifiers } from "./utils/IBCIdentifiers.sol";
 import { ILightClient } from "./interfaces/ILightClient.sol";
 import { IICS02ClientErrors } from "./errors/IICS02ClientErrors.sol";
+import { Ownable } from "@openzeppelin/contracts/access/Ownable.sol";
 
-contract ICS02Client is IICS02Client, IICS02ClientErrors {
+contract ICS02Client is IICS02Client, IICS02ClientErrors, Ownable {
     /// @dev clientId => counterpartyInfo
     mapping(string => CounterpartyInfo) private counterpartyInfos;
     /// @dev clientId => client
     mapping(string => ILightClient) private clients;
     /// @dev clientType => nextClientSeq
     mapping(string => uint32) private nextClientSeq;
 
+    /// @param owner_ The owner of the contract
+    constructor(address owner_) Ownable(owner_) { }
+
     /// @notice Generates the next client identifier
     /// @param clientType The client type
     /// @return The next client identifier
@@ -28,12 +32,22 @@ contract ICS02Client is IICS02Client, IICS02ClientErrors {
         return string.concat(clientType, "-", Strings.toString(seq));
     }
 
-    function getCounterparty(string calldata clientId) external view returns (CounterpartyInfo memory) {
-        return counterpartyInfos[clientId];
+    function getCounterparty(string calldata clientId) public view returns (CounterpartyInfo memory) {
+        CounterpartyInfo memory counterpartyInfo = counterpartyInfos[clientId];
+        if (bytes(counterpartyInfo.clientId).length == 0) {
+            revert IBCClientNotFound(clientId);
+        }
+
+        return counterpartyInfo;
     }
 
-    function getClient(string calldata clientId) external view returns (ILightClient) {
-        return clients[clientId];
+    function getClient(string calldata clientId) public view returns (ILightClient) {
+        ILightClient client = clients[clientId];
+        if (client == ILightClient(address(0))) {
+            revert IBCClientNotFound(clientId);
+        }
+
+        return client;
     }
 
     function addClient(
@@ -50,17 +64,32 @@ contract ICS02Client is IICS02Client, IICS02ClientErrors {
         return clientId;
     }
 
+    function migrateClient(string calldata subjectClientId, string calldata substituteClientId) external onlyOwner {
+        getClient(subjectClientId); // Ensure subject client exists
+        ILightClient substituteClient = getClient(substituteClientId);
+
+        getCounterparty(subjectClientId); // Ensure subject client's counterparty exists
+        CounterpartyInfo memory substituteCounterpartyInfo = getCounterparty(substituteClientId);
+
+        counterpartyInfos[subjectClientId] = substituteCounterpartyInfo;
+        clients[subjectClientId] = substituteClient;
+    }
+
     function updateClient(
         string calldata clientId,
         bytes calldata updateMsg
     )
         external
         returns (ILightClient.UpdateResult)
     {
-        return clients[clientId].updateClient(updateMsg);
+        return getClient(clientId).updateClient(updateMsg);
     }
 
     function submitMisbehaviour(string calldata clientId, bytes calldata misbehaviourMsg) external {
-        clients[clientId].misbehaviour(misbehaviourMsg);
+        getClient(clientId).misbehaviour(misbehaviourMsg);
+    }
+
+    function upgradeClient(string calldata clientId, bytes calldata upgradeMsg) external {
+        getClient(clientId).upgradeClient(upgradeMsg);
     }
 }

src/ICS26Router.sol

@@ -110,7 +110,7 @@ contract ICS26Router is IICS26Router, IBCStore, Ownable, IICS26RouterErrors, Ree
             kvPair: ILightClientMsgs.KVPair({ path: commitmentPath, value: abi.encodePacked(commitmentBz) })
         });
 
-        ics02Client.getClient(msg_.packet.destChannel).verifyMembership(membershipMsg);
+        ics02Client.getClient(msg_.packet.destChannel).membership(membershipMsg);
         if (msg_.packet.timeoutTimestamp <= block.timestamp) {
             revert IBCInvalidTimeoutTimestamp(msg_.packet.timeoutTimestamp, block.timestamp);
         }
@@ -156,7 +156,7 @@ contract ICS26Router is IICS26Router, IBCStore, Ownable, IICS26RouterErrors, Ree
             kvPair: ILightClientMsgs.KVPair({ path: commitmentPath, value: abi.encodePacked(commitmentBz) })
         });
 
-        ics02Client.getClient(msg_.packet.sourceChannel).verifyMembership(membershipMsg);
+        ics02Client.getClient(msg_.packet.sourceChannel).membership(membershipMsg);
 
         app.onAcknowledgementPacket(
             IIBCAppCallbacks.OnAcknowledgementPacketCallback({
@@ -194,8 +194,7 @@ contract ICS26Router is IICS26Router, IBCStore, Ownable, IICS26RouterErrors, Ree
             kvPair: ILightClientMsgs.KVPair({ path: receiptPath, value: bytes("") })
         });
 
-        uint32 counterpartyTimestamp =
-            ics02Client.getClient(msg_.packet.sourceChannel).verifyMembership(nonMembershipMsg);
+        uint32 counterpartyTimestamp = ics02Client.getClient(msg_.packet.sourceChannel).membership(nonMembershipMsg);
         if (counterpartyTimestamp < msg_.packet.timeoutTimestamp) {
             revert IBCInvalidTimeoutTimestamp(msg_.packet.timeoutTimestamp, counterpartyTimestamp);
         }

src/errors/IICS02ClientErrors.sol

@@ -4,4 +4,7 @@ pragma solidity >=0.8.25;
 interface IICS02ClientErrors {
     /// @param clientType client type
     error IBCInvalidClientType(string clientType);
+
+    /// @param clientId client identifier
+    error IBCClientNotFound(string clientId);
 }

src/interfaces/IICS02Client.sol

@@ -30,6 +30,12 @@ interface IICS02Client is IICS02ClientMsgs {
         external
         returns (string memory);
 
+    /// @notice Migrate the underlying client of the subject client to the substitute client.
+    /// @dev This is a privilaged operation, only the owner of ICS02Client can call this function.
+    /// @param subjectClientId The client identifier of the subject client
+    /// @param substituteClientId The client identifier of the substitute client
+    function migrateClient(string calldata subjectClientId, string calldata substituteClientId) external;
+
     /// @notice Updates the client given the client identifier.
     /// @param clientId The client identifier
     /// @param updateMsg The update message
@@ -45,4 +51,9 @@ interface IICS02Client is IICS02ClientMsgs {
     /// @param clientId The client identifier
     /// @param misbehaviourMsg The misbehaviour message
     function submitMisbehaviour(string calldata clientId, bytes calldata misbehaviourMsg) external;
+
+    /// @notice Upgrades the client with the given client identifier.
+    /// @param clientId The client identifier
+    /// @param upgradeMsg The upgrade message
+    function upgradeClient(string calldata clientId, bytes calldata upgradeMsg) external;
 }

src/interfaces/ILightClient.sol

@@ -13,9 +13,13 @@ interface ILightClient is ILightClientMsgs {
 
     /// @notice Querying the (non)membership of the key-value pairs
     /// @return The unix timestamp of the verification height in the counterparty chain in seconds.
-    function verifyMembership(MsgMembership calldata msg_) external view returns (uint32);
+    function membership(MsgMembership calldata msg_) external view returns (uint32);
 
     /// @notice Misbehaviour handling, moves the light client to the frozen state if misbehaviour is detected
     /// @param misbehaviourMsg The misbehaviour message
     function misbehaviour(bytes calldata misbehaviourMsg) external;
+
+    /// @notice Upgrading the client
+    /// @param upgradeMsg The upgrade message
+    function upgradeClient(bytes calldata upgradeMsg) external;
 }