feat(token-handler)!: added automatic token migration

.changeset/quick-ants-crash.md

@@ -0,0 +1,5 @@
+---
+'@axelar-network/interchain-token-service': minor
+---
+
+Add auto-migration of minter for native interchain tokens

contracts/TokenHandler.sol

@@ -35,6 +35,8 @@ contract TokenHandler is ITokenHandler, ITokenManagerType, ReentrancyGuard, Crea
 
         (uint256 tokenManagerType, address tokenAddress) = ITokenManagerProxy(tokenManager).getImplementationTypeAndTokenAddress();
 
+        _migrateToken(tokenManager, tokenAddress, tokenManagerType);
+
         /// @dev Track the flow amount being received via the message
         ITokenManager(tokenManager).addFlowIn(amount);
 
@@ -44,20 +46,15 @@ contract TokenHandler is ITokenHandler, ITokenManagerType, ReentrancyGuard, Crea
             tokenManagerType == uint256(TokenManagerType.MINT_BURN_FROM)
         ) {
             _mintToken(ITokenManager(tokenManager), tokenAddress, to, amount);
-            return (amount, tokenAddress);
-        }
-
-        if (tokenManagerType == uint256(TokenManagerType.LOCK_UNLOCK)) {
+        } else if (tokenManagerType == uint256(TokenManagerType.LOCK_UNLOCK)) {
             _transferTokenFrom(tokenAddress, tokenManager, to, amount);
-            return (amount, tokenAddress);
-        }
-
-        if (tokenManagerType == uint256(TokenManagerType.LOCK_UNLOCK_FEE)) {
+        } else if (tokenManagerType == uint256(TokenManagerType.LOCK_UNLOCK_FEE)) {
             amount = _transferTokenFromWithFee(tokenAddress, tokenManager, to, amount);
-            return (amount, tokenAddress);
+        } else {
+            revert UnsupportedTokenManagerType(tokenManagerType);
         }
 
-        revert UnsupportedTokenManagerType(tokenManagerType);
+        return (amount, tokenAddress);
     }
 
     /**
@@ -75,6 +72,8 @@ contract TokenHandler is ITokenHandler, ITokenManagerType, ReentrancyGuard, Crea
 
         if (tokenOnly && msg.sender != tokenAddress) revert NotToken(msg.sender, tokenAddress);
 
+        _migrateToken(tokenManager, tokenAddress, tokenManagerType);
+
         if (
             tokenManagerType == uint256(TokenManagerType.NATIVE_INTERCHAIN_TOKEN) || tokenManagerType == uint256(TokenManagerType.MINT_BURN)
         ) {
@@ -176,4 +175,17 @@ contract TokenHandler is ITokenHandler, ITokenManagerType, ReentrancyGuard, Crea
     function _burnTokenFrom(address tokenAddress, address from, uint256 amount) internal {
         IERC20(tokenAddress).safeCall(abi.encodeWithSelector(IERC20BurnableFrom.burnFrom.selector, from, amount));
     }
+
+    /**
+     * @notice This transfers mintership of a native Interchain token to the tokenManager if ITS is still its minter.
+     * It does nothing if ITS is not the minter. This ensures that interchain tokens are auto-migrated without requiring a downtime for ITS.
+     * @param tokenManager The token manager address to transfer mintership to.
+     * @param tokenAddress The address of the token to transfer mintership of.
+     * @param tokenManagerType The token manager type for the token.
+     */
+    function _migrateToken(address tokenManager, address tokenAddress, uint256 tokenManagerType) internal {
+        if (tokenManagerType == uint256(TokenManagerType.NATIVE_INTERCHAIN_TOKEN) && IMinter(tokenAddress).isMinter(address(this))) {
+            IMinter(tokenAddress).transferMintership(tokenManager);
+        }
+    }
 }

test/InterchainTokenService.js

@@ -2981,6 +2981,62 @@ describe('Interchain Token Service', () => {
                 'NotOwner',
             );
         });
+
+        it('Should migrate a token automatically when sending token only once', async () => {
+            const name = 'migrated token';
+            const symbol = 'MT';
+            const decimals = 53;
+            const amount1 = 123;
+            const amount2 = 456;
+            const destinationAddress = '0x1234';
+
+            const [token, tokenManager, tokenId] = await deployFunctions.interchainToken(
+                service,
+                name,
+                symbol,
+                decimals,
+                service.address,
+                amount1 + amount2,
+            );
+
+            await expect(service.interchainTransfer(tokenId, destinationChain, destinationAddress, amount1, '0x', 0))
+                .to.emit(token, 'RolesRemoved')
+                .withArgs(service.address, 1 << MINTER_ROLE)
+                .to.emit(token, 'RolesAdded')
+                .withArgs(tokenManager.address, 1 << MINTER_ROLE);
+
+            await expect(service.interchainTransfer(tokenId, destinationChain, destinationAddress, amount2, '0x', 0))
+                .to.not.emit(token, 'RolesRemoved')
+                .to.not.emit(token, 'RolesAdded');
+        });
+
+        it('Should migrate a token automatically when receiving token', async () => {
+            const name = 'migrated token';
+            const symbol = 'MT';
+            const decimals = 53;
+            const amount = 123;
+            const sourceAddress = '0x1234';
+
+            const [token, tokenManager, tokenId] = await deployFunctions.interchainToken(service, name, symbol, decimals, service.address);
+
+            const payload = defaultAbiCoder.encode(
+                ['uint256', 'bytes32', 'bytes', 'bytes', 'uint256', 'bytes'],
+                [MESSAGE_TYPE_INTERCHAIN_TRANSFER, tokenId, sourceAddress, wallet.address, amount, '0x'],
+            );
+            let commandId = await approveContractCall(gateway, destinationChain, service.address, service.address, payload);
+
+            await expect(service.execute(commandId, destinationChain, service.address, payload))
+                .to.emit(token, 'RolesRemoved')
+                .withArgs(service.address, 1 << MINTER_ROLE)
+                .to.emit(token, 'RolesAdded')
+                .withArgs(tokenManager.address, 1 << MINTER_ROLE);
+
+            commandId = await approveContractCall(gateway, destinationChain, service.address, service.address, payload);
+
+            await expect(service.execute(commandId, destinationChain, service.address, payload))
+                .to.not.emit(token, 'RolesRemoved')
+                .to.not.emit(token, 'RolesAdded');
+        });
     });
 
     describe('Bytecode checks [ @skip-on-coverage ]', () => {