document limitation to EVM chains

Author: Amxx

contracts/crosschain/axelar/AxelarGatewayAdapter.sol

@@ -15,6 +15,12 @@ import {IERC7786Receiver} from "../../interfaces/IERC7786.sol";
  *
  * The contract implements AxelarExecutable's {_execute} function to execute the message, converting Axelar's native
  * workflow into the standard ERC-7786.
+ *
+ * NOTE: While both ERC-7786 and Axelar do support non-evm chains, this adaptor does not. This limitation comes from
+ * the translation of the ERC-7930 interoperable address (binary objects -- bytes) to strings. This is necessary
+ * because Axelar uses string to represend addresses. For EVM network, this adapter uses a checksum hex string
+ * representation. Other networks would require a different encoding. Ideally we would have a single encoding for all
+ * networks (could be base58, base64, ...) but Axelar doesn't support that.
  */
 // slither-disable-next-line locked-ether
 contract AxelarGatewayAdapter is IERC7786GatewaySource, Ownable, AxelarExecutable {
@@ -38,6 +44,7 @@ contract AxelarGatewayAdapter is IERC7786GatewaySource, Ownable, AxelarExecutabl
     error UnsupportedNativeTransfer();
     error InvalidOriginGateway(string axelarSourceChain, string axelarSourceAddress);
     error ReceiverExecutionFailed();
+    error UnsupportedChainType(bytes2 chainType);
     error UnsupportedERC7930Chain(bytes erc7930binary);
     error UnsupportedAxelarChain(string axelar);
     error InvalidChainIdentifier(bytes erc7930binary);
@@ -132,7 +139,7 @@ contract AxelarGatewayAdapter is IERC7786GatewaySource, Ownable, AxelarExecutabl
         (bytes2 chainType, bytes calldata chainReference, ) = recipient.parseV1Calldata();
         bytes memory remoteGateway = getRemoteGateway(chainType, chainReference);
         string memory axelarDestination = getAxelarChain(InteroperableAddress.formatV1(chainType, chainReference, ""));
-        string memory axelarTarget = address(bytes20(remoteGateway)).toChecksumHexString(); // TODO non-evm chains?
+        string memory axelarTarget = _stringifyAddress(chainType, remoteGateway);
 
         gateway().callContract(axelarDestination, axelarTarget, adapterPayload);
 
@@ -162,18 +169,31 @@ contract AxelarGatewayAdapter is IERC7786GatewaySource, Ownable, AxelarExecutabl
             (bytes, bytes, bytes)
         );
 
-        // Axelar to ERC-7930 translation
-        bytes memory addr = getRemoteGateway(getErc7930Chain(axelarSourceChain));
+        // variable lifecycle: avoid stack-too-deep
+        {
+            // Axelar to ERC-7930 translation
+            (bytes2 chainType, bytes memory chainReference, ) = getErc7930Chain(axelarSourceChain).parseV1();
+            bytes memory addr = getRemoteGateway(chainType, chainReference);
 
-        // check message validity
-        // - `axelarSourceAddress` is the remote gateway on the origin chain.
-        require(
-            address(bytes20(addr)).toChecksumHexString().equal(axelarSourceAddress), // TODO non-evm chains?
-            InvalidOriginGateway(axelarSourceChain, axelarSourceAddress)
-        );
+            // check message validity
+            // - `axelarSourceAddress` is the remote gateway on the origin chain.
+            require(
+                _stringifyAddress(chainType, addr).equal(axelarSourceAddress),
+                InvalidOriginGateway(axelarSourceChain, axelarSourceAddress)
+            );
+        }
 
         (, address target) = recipient.parseEvmV1();
         bytes4 result = IERC7786Receiver(target).receiveMessage(commandId, sender, payload);
         require(result == IERC7786Receiver.receiveMessage.selector, ReceiverExecutionFailed());
     }
+
+    /// @dev ERC-7930 to Axelar address translation. Currently only supports EVM chains.
+    function _stringifyAddress(bytes2 chainType, bytes memory addr) internal virtual returns (string memory) {
+        if (chainType == 0) {
+            return address(bytes20(addr)).toChecksumHexString();
+        } else {
+            revert UnsupportedChainType(chainType);
+        }
+    }
 }