1 files changed, 35 insertions, 13 deletions
diff --git a/packages/contracts/src/contracts/current/protocol/AssetProxy/ERC20Proxy.sol b/packages/contracts/src/contracts/current/protocol/AssetProxy/ERC20Proxy.sol
index 2c321e134..dd25bf41a 100644
--- a/packages/contracts/src/contracts/current/protocol/AssetProxy/ERC20Proxy.sol
+++ b/packages/contracts/src/contracts/current/protocol/AssetProxy/ERC20Proxy.sol
@@ -34,34 +34,30 @@ contract ERC20Proxy is
     uint8 constant PROXY_ID = 1;
 
     /// @dev Internal version of `transferFrom`.
-    /// @param assetMetadata Encoded byte array.
+    /// @param assetData Encoded byte array.
     /// @param from Address to transfer asset from.
     /// @param to Address to transfer asset to.
     /// @param amount Amount of asset to transfer.
     function transferFromInternal(
-        bytes memory assetMetadata,
+        bytes memory assetData,
         address from,
         address to,
         uint256 amount
     )
         internal
     {
-        // Data must be intended for this proxy.
-        uint256 length = assetMetadata.length;
+        // Decode asset data.
+        (
+            uint8 proxyId,
+            address token
+        ) = decodeERC20AssetData(assetData);
 
+        // Data must be intended for this proxy.
         require(
-            length == 21,
-            LENGTH_21_REQUIRED
-        );
-        // TODO: Is this too inflexible in the future?
-        require(
-            uint8(assetMetadata[length - 1]) == PROXY_ID,
+            proxyId == PROXY_ID,
             ASSET_PROXY_ID_MISMATCH
         );
 
-        // Decode metadata.
-        address token = readAddress(assetMetadata, 0);
-
         // Transfer tokens.
         bool success = IERC20Token(token).transferFrom(from, to, amount);
         require(
@@ -79,4 +75,30 @@ contract ERC20Proxy is
     {
         return PROXY_ID;
     }
+
+    /// @dev Decodes ERC20 Asset data.
+    /// @param assetData Encoded byte array.
+    /// @return proxyId Intended ERC20 proxy id.
+    /// @return token ERC20 token address.
+    function decodeERC20AssetData(bytes memory assetData)
+        internal
+        pure
+        returns (
+            uint8 proxyId,
+            address token
+        )
+    {
+        // Validate encoded data length
+        uint256 length = assetData.length;
+        require(
+            length == 21,
+            LENGTH_21_REQUIRED
+        );
+
+        // Decode data
+        token = readAddress(assetData, 0);
+        proxyId = uint8(assetData[length - 1]);
+
+        return (proxyId, token);
+    }
 }