From 845a42e73aa619274b424dcb03add7a2ba17f6ef Mon Sep 17 00:00:00 2001
From: Lawrence Forman <me@merklejerk.com>
Date: Tue, 30 Jun 2020 15:58:06 -0400
Subject: [PATCH] `@0x/asset-proxy`: Fix DFB instability

---
 contracts/asset-proxy/CHANGELOG.json          |  9 ++++++++
 .../src/bridges/DexForwarderBridge.sol        | 13 +++++------
 .../asset-proxy/test/dex_forwarder_bridge.ts  | 22 +++++++++----------
 3 files changed, 25 insertions(+), 19 deletions(-)

diff --git a/contracts/asset-proxy/CHANGELOG.json b/contracts/asset-proxy/CHANGELOG.json
index a630a14dcc..b6ef247c7f 100644
--- a/contracts/asset-proxy/CHANGELOG.json
+++ b/contracts/asset-proxy/CHANGELOG.json
@@ -1,4 +1,13 @@
 [
+    {
+        "version": "3.3.1",
+        "changes": [
+            {
+                "note": "Fix instability with DFB.",
+                "pr": 2616
+            }
+        ]
+    },
     {
         "version": "3.3.0",
         "changes": [
diff --git a/contracts/asset-proxy/contracts/src/bridges/DexForwarderBridge.sol b/contracts/asset-proxy/contracts/src/bridges/DexForwarderBridge.sol
index 9faf278041..33c763f2bb 100644
--- a/contracts/asset-proxy/contracts/src/bridges/DexForwarderBridge.sol
+++ b/contracts/asset-proxy/contracts/src/bridges/DexForwarderBridge.sol
@@ -75,14 +75,18 @@ contract DexForwarderBridge is
         freesGasTokensFromCollector
         returns (bytes4 success)
     {
-        require(msg.sender == _getERC20BridgeProxyAddress(), "DexForwarderBridge/SENDER_NOT_AUTHORIZED");
+        require(
+            msg.sender == _getERC20BridgeProxyAddress(),
+            "DexForwarderBridge/SENDER_NOT_AUTHORIZED"
+        );
         TransferFromState memory state;
         (
             state.inputToken,
             state.calls
         ) = abi.decode(bridgeData, (address, BridgeCall[]));
 
-        state.initialInputTokenBalance = IERC20Token(state.inputToken).balanceOf(address(this));
+        state.initialInputTokenBalance =
+            IERC20Token(state.inputToken).balanceOf(address(this));
 
         for (uint256 i = 0; i < state.calls.length; ++i) {
             // Stop if the we've sold all our input tokens.
@@ -122,11 +126,6 @@ contract DexForwarderBridge is
                 );
             }
         }
-        // Revert if we were not able to sell our entire input token balance.
-        require(
-            state.totalInputTokenSold >= state.initialInputTokenBalance,
-            "DexForwarderBridge/INCOMPLETE_FILL"
-        );
         // Always succeed.
         return BRIDGE_SUCCESS;
     }
diff --git a/contracts/asset-proxy/test/dex_forwarder_bridge.ts b/contracts/asset-proxy/test/dex_forwarder_bridge.ts
index 687dc02c1e..2954fea693 100644
--- a/contracts/asset-proxy/test/dex_forwarder_bridge.ts
+++ b/contracts/asset-proxy/test/dex_forwarder_bridge.ts
@@ -30,7 +30,6 @@ blockchainTests.resets('DexForwarderBridge unit tests', env => {
     const BRIDGE_SUCCESS = '0xdc1600f3';
     const BRIDGE_FAILURE = '0xffffffff';
     const BRIDGE_REVERT_ERROR = 'oopsie';
-    const INCOMPLETE_FILL_REVERT = 'DexForwarderBridge/INCOMPLETE_FILL';
     const NOT_AUTHORIZED_REVERT = 'DexForwarderBridge/SENDER_NOT_AUTHORIZED';
     const DEFAULTS = {
         toAddress: randomAddress(),
@@ -165,27 +164,26 @@ blockchainTests.resets('DexForwarderBridge unit tests', env => {
             await callBridgeTransferFromAsync({ bridgeData, sellAmount: ZERO_AMOUNT });
         });
 
-        it('fails with no bridge calls and an input balance', async () => {
+        it('succeeds with no bridge calls and an input balance', async () => {
             const bridgeData = dexForwarderBridgeDataEncoder.encode({
                 inputToken,
                 calls: [],
             });
-            return expect(callBridgeTransferFromAsync({ bridgeData, sellAmount: new BigNumber(1) })).to.revertWith(
-                INCOMPLETE_FILL_REVERT,
-            );
+            await callBridgeTransferFromAsync({
+                bridgeData,
+                sellAmount: new BigNumber(1),
+            });
         });
 
-        it('fails if entire input token balance is not consumed', async () => {
+        it('succeeds if entire input token balance is not consumed', async () => {
             const bridgeData = dexForwarderBridgeDataEncoder.encode({
                 inputToken,
                 calls: allBridgeCalls,
             });
-            return expect(
-                callBridgeTransferFromAsync({
-                    bridgeData,
-                    sellAmount: totalFillableInputAmount.plus(1),
-                }),
-            ).to.revertWith(INCOMPLETE_FILL_REVERT);
+            await callBridgeTransferFromAsync({
+                bridgeData,
+                sellAmount: totalFillableInputAmount.plus(1),
+            });
         });
 
         it('fails if not authorized', async () => {