feat(l2): implement ERC20 bridge #3241

iovoid · 2025-06-19T20:12:09Z

Motivation

We want to be able to bridge ERC20 tokens.

Description

The inner workings are explained on #3223

…ssenger

Co-authored-by: Tomás Grüner <[email protected]>

This reverts commit 2273223.

github-actions · 2025-06-19T20:14:26Z

Lines of code report

Total lines added: 250
Total lines removed: 158
Total lines changed: 408

Detailed view

+--------------------------------------------------+-------+------+
| File                                             | Lines | Diff |
+--------------------------------------------------+-------+------+
| ethrex/crates/l2/contracts/bin/deployer/error.rs | 27    | -2   |
+--------------------------------------------------+-------+------+
| ethrex/crates/l2/contracts/bin/deployer/main.rs  | 623   | -156 |
+--------------------------------------------------+-------+------+
| ethrex/crates/l2/sdk/src/sdk.rs                  | 762   | +250 |
+--------------------------------------------------+-------+------+

crates/l2/contracts/src/l2/CommonBridgeL2.sol

crates/l2/contracts/src/l1/CommonBridge.sol

crates/l2/contracts/src/l2/L1Messenger.sol

crates/l2/contracts/src/l2/interfaces/IERC20L2.sol

Co-authored-by: Manuel Iñaki Bilbao <[email protected]>

MegaRedHand · 2025-06-24T20:39:56Z

crates/l2/contracts/src/l1/CommonBridge.sol

+    /// @notice How much of each L1 token was deposited to each L2 token.
+    /// @dev Stored as L1 -> L2 -> amount
+    /// @dev Prevents L2 tokens from faking their L1 address and stealing tokens
+    mapping (address => mapping (address => uint256)) public depositsERC20;


We should consider moving this to the L2 for reduced gas costs. Opened an issue for that: #3299

crates/l2/contracts/src/l1/CommonBridge.sol

crates/l2/contracts/src/l2/CommonBridgeL2.sol

crates/l2/tests/tests.rs

fkrause98 · 2025-06-24T21:32:56Z

crates/l2/contracts/bin/system_contracts_updater/main.rs

 use genesis_tool::genesis::write_genesis_as_json;
 mod cli;
 mod error;

 fn main() -> Result<(), SystemContractsUpdaterError> {
    let opts = SystemContractsUpdaterOptions::parse();
    compile_contract(&opts.contracts_path, "src/l2/CommonBridgeL2.sol", true)?;
-    compile_contract(&opts.contracts_path, "src/l2/L1Messenger.sol", true)?;
+    compile_contract(&opts.contracts_path, "src/l2/L2ToL1Messenger.sol", true)?;


Can this contract change in the future? Consider this scenario:

You update the code, this yields a new bytecode.

You then add the bytecode to the genesis file like what happens below, on lines 42-45.

If the contract was already deployed, this would result in a different genesis file from the original one, right?

Of course, feel free to correct me.

It would result in a different genesis, but that is intended. The purpose of system_contracts_updater is to update the genesis file with the new bytecode for the system contracts.

As for the contract, it could change albeit very rarely. If you wanted, for example, to allow submitting signed messages on behalf of other users.

crates/l2/contracts/src/example/L2ERC20.sol

crates/l2/contracts/src/l1/CommonBridge.sol

crates/l2/contracts/src/l2/CommonBridgeL2.sol

ManuelBilbao · 2025-06-26T16:34:15Z

crates/l2/sdk/src/sdk.rs

+    }
+}
+
+pub fn download_contract_deps(contracts_path: &Path) -> Result<(), GitError> {


I'm not quite agree putting this in the SDK. @ilitteri what do you think?

ManuelBilbao · 2025-06-26T16:36:17Z

crates/l2/contracts/src/example/L2ERC20.sol

+import "@openzeppelin/contracts/token/ERC20/ERC20.sol";
+import "../l2/interfaces/IERC20L2.sol";
+
+/// @title OnChainProposer contract.


This is incorrect

Fixed in 06232b5.

ManuelBilbao · 2025-06-26T16:37:28Z

crates/l2/contracts/src/example/L2ERC20.sol

+/// @author LambdaClass
+contract TestTokenL2 is ERC20, IERC20L2 {
+    address public L1_TOKEN = address(0);
+    address public constant BRIDGE =  0x000000000000000000000000000000000000FFff;


Should we put the bridge address on the interface so token operators don't mess up?

ManuelBilbao · 2025-06-26T16:41:47Z

crates/l2/contracts/src/l1/CommonBridge.sol

+        IERC20(tokenL1).safeTransferFrom(msg.sender, address(this), amount);
+
+        depositsERC20[tokenL1][tokenL2] += amount;


Should we take care of reentrancy here?

Let's remove that by swapping these two lines (the external call and storage access), just to be sure.

I don't think any attacks are possible, though, since here we're not sending any value out of the bridge. Any token transfers that result in recursive deposits will only further increase this amount, checking that the transfer doesn't revert any of those times.

ManuelBilbao · 2025-06-26T16:46:35Z

crates/l2/contracts/src/l2/CommonBridgeL2.sol

+        try this._mintERC20(tokenL1, tokenL2, destination, amount) {
+        } catch {
+            _withdrawERC20(tokenL1, tokenL2, destination, amount);
+        }


Can we use if (!success) instead of try-catch?

ManuelBilbao · 2025-06-26T16:49:32Z

crates/l2/contracts/src/l2/CommonBridgeL2.sol

+        _withdrawERC20(tokenL1, tokenL2, destination, amount);
+    }
+
+    function _withdrawERC20(address tokenL1, address tokenL2, address destination, uint256 amount) private {


I would use a better name here. Something like sendERC20WithdrawToL1 (there should be better ones)

ManuelBilbao · 2025-06-26T16:57:03Z

crates/l2/contracts/src/l1/CommonBridge.sol

+        IERC20(tokenL1).safeTransfer(msg.sender, claimedAmount);
+    }
+
+    function _claimWithdrawal(


Let's find better names for this functions, we have claimWithdrawal, _claimWithdrawal, claimWithdrawalERC20, _claimWithdrawalProof and _verifyWithdrawProof (if I'm not missing anyone else). It's hard to understand what does each one do

MegaRedHand · 2025-06-26T17:13:42Z

crates/l2/contracts/src/l1/CommonBridge.sol

-    function _deposit(DepositValues memory depositValues) private {
-        require(msg.value > 0, "CommonBridge: amount to deposit is zero");
+    function _deposit(address from, DepositValues memory depositValues) private {
+        depositsERC20[ETH_TOKEN][ETH_TOKEN] += msg.value;


This line is confusing since the function is also being called on non-ETH deposits. We should move it to the caller's side

iovoid and others added 23 commits June 12, 2025 17:24

add L1Messenger contract

b7330b0

fix function name

9c87eee

start rewriting

25cbdd1

Do withdrawal->l1message renames. Merge branch 'main' into feat/l1-me…

7346be0

…ssenger

fix and cleanup

09ea674

Merge branch 'main' into feat/l1-messenger

c402545

rename in based

895d0fe

update docs

a618588

add l1messenger to system contract updater

0212475

fix behavior on single-node tree

d902587

return all proofs in rpc

06cb2ee

rename variables

5655820

clarify that l1message has the hash of the data

1bf5eeb

Send bytes32 hash instead of the whole data

6c0be9b

update docs

52cea43

clarify contract documentation

37af32d

Fix typo

4173ddd

Co-authored-by: Tomás Grüner <[email protected]>

reorder fields

c8573f6

Merge branch 'main' into feat/l1-messenger

acd8840

fix event signature

ef3f7b3

fix merkle on n=1

2273223

Revert "fix merkle on n=1"

d57860f

This reverts commit 2273223.

implement erc20 bridging

df461d3

iovoid changed the title ~~feat(l2): ERC20 bridge~~ feat(l2): implement ERC20 bridge Jun 19, 2025

MegaRedHand reviewed Jun 19, 2025

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crates/l2/contracts/src/l2/CommonBridgeL2.sol Outdated Show resolved Hide resolved

MegaRedHand reviewed Jun 19, 2025

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iovoid added 3 commits June 23, 2025 09:52

use same format for ETH and ERC20

9c897dc

use typechecked call for mint

9a21ea3

update l2 genesis

3e35cc7

iovoid requested review from ManuelBilbao and a team as code owners June 23, 2025 21:01

ManuelBilbao reviewed Jun 23, 2025

View reviewed changes

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ManuelBilbao reviewed Jun 23, 2025

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crates/l2/contracts/src/l2/L1Messenger.sol Outdated Show resolved Hide resolved

crates/l2/contracts/src/l2/interfaces/IERC20L2.sol Outdated Show resolved Hide resolved

iovoid and others added 2 commits June 24, 2025 09:19

Fix typo

b69f916

Co-authored-by: Manuel Iñaki Bilbao <[email protected]>

rename L1Messenger->L2ToL1Messenger

b12f7ec

ManuelBilbao added the L2 Rollup client label Jun 24, 2025

iovoid added 4 commits June 24, 2025 11:21

Merge branch 'main' into feat/erc20-bridge

7e8e08d

fix merge

092dfd3

fix merge

72b6b8c

fix merge

18013bc

iovoid force-pushed the feat/erc20-bridge branch from d2de067 to 18013bc Compare June 24, 2025 18:04

MegaRedHand reviewed Jun 24, 2025

View reviewed changes

fkrause98 reviewed Jun 24, 2025

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fkrause98 reviewed Jun 24, 2025

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crates/l2/contracts/src/l2/CommonBridgeL2.sol Show resolved Hide resolved

fkrause98 reviewed Jun 24, 2025

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crates/l2/contracts/src/l2/CommonBridgeL2.sol Show resolved Hide resolved

fkrause98 reviewed Jun 24, 2025

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fkrause98 reviewed Jun 24, 2025

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MegaRedHand reviewed Jun 24, 2025

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iovoid added 5 commits June 26, 2025 09:52

implement suggestions

fe00936

fix typoed function

4f2b9f1

Merge branch 'main' into feat/erc20-bridge

057256a

clone contract dependencies when running tests

c1e7d3e

clippy

b9dee2f

MegaRedHand approved these changes Jun 26, 2025

View reviewed changes

MegaRedHand requested a review from ManuelBilbao June 26, 2025 15:58

debug tdx ci

53eaa11

ManuelBilbao reviewed Jun 26, 2025

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MegaRedHand reviewed Jun 26, 2025

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fix unchanged comment

06232b5

		IERC20(tokenL1).safeTransferFrom(msg.sender, address(this), amount);

		depositsERC20[tokenL1][tokenL2] += amount;

feat(l2): implement ERC20 bridge #3241

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feat(l2): implement ERC20 bridge #3241

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iovoid commented Jun 19, 2025

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