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@0x/contracts-asset-proxy: Remove unecessary token allowance when coming from WETH.

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This commit is contained in:
Lawrence Forman
2019-10-05 22:37:51 -05:00
parent ef6e691646
commit dbf22583b5
2 changed files with 19 additions and 45 deletions
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41
contracts/asset-proxy/contracts/src/bridges/UniswapBridge.sol
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@@ -40,7 +40,6 @@ contract UniswapBridge is
// Struct to hold `withdrawTo()` local variables in memory and to avoid
// stack overflows.
struct WithdrawToState {
address exchangeTokenAddress;
IUniswapExchange exchange;
uint256 fromTokenBalance;
IEtherToken weth;
@@ -82,15 +81,11 @@ contract UniswapBridge is
return BRIDGE_SUCCESS;
}
// Get the exchange token for the token pair.
state.exchangeTokenAddress = _getUniswapExchangeTokenAddressForTokenPair(
// Get the exchange for the token pair.
state.exchange = _getUniswapExchangeForTokenPair(
fromTokenAddress,
toTokenAddress
);
// Get the exchange.
state.exchange = _getUniswapExchangeForToken(state.exchangeTokenAddress);
// Grant an allowance to the exchange.
_grantExchangeAllowance(state.exchange, state.exchangeTokenAddress);
// Get our balance of `fromTokenAddress` token.
state.fromTokenBalance = IERC20Token(fromTokenAddress).balanceOf(address(this));
// Get the weth contract.
@@ -113,6 +108,8 @@ contract UniswapBridge is
// Convert from a token to WETH.
} else if (toTokenAddress == address(state.weth)) {
// Grant the exchange an allowance.
_grantExchangeAllowance(state.exchange, fromTokenAddress);
// Buy as much ETH with `fromTokenAddress` token as possible.
uint256 ethBought = state.exchange.tokenToEthSwapInput(
// Sell all tokens we hold.
@@ -129,6 +126,8 @@ contract UniswapBridge is
// Convert from one token to another.
} else {
// Grant the exchange an allowance.
_grantExchangeAllowance(state.exchange, fromTokenAddress);
// Buy as much `toTokenAddress` token with `fromTokenAddress` token
// and transfer it to `to`.
state.exchange.tokenToTokenTransferInput(
@@ -193,36 +192,26 @@ contract UniswapBridge is
IERC20Token(tokenAddress).approve(address(exchange), uint256(-1));
}
/// @dev Retrieves the uniswap exchange token address for a given token pair.
/// @dev Retrieves the uniswap exchange for a given token pair.
/// In the case of a WETH-token exchange, this will be the non-WETH token.
/// In th ecase of a token-token exchange, this will be the first token.
/// @param fromTokenAddress The address of the token we are converting from.
/// @param toTokenAddress The address of the token we are converting to.
/// @return exchangeTokenAddress The address of the token for the uniswap
/// exchange.
function _getUniswapExchangeTokenAddressForTokenPair(
/// @return exchange The uniswap exchange.
function _getUniswapExchangeForTokenPair(
address fromTokenAddress,
address toTokenAddress
)
private
view
returns (address exchangeTokenAddress)
{
// Whichever isn't WETH is the exchange token.
if (fromTokenAddress != address(getWethContract())) {
return fromTokenAddress;
}
return toTokenAddress;
}
/// @dev Retrieves the uniswap exchange contract for a given token.
/// @return exchange The exchange contract for the token.
function _getUniswapExchangeForToken(address tokenAddress)
private
view
returns (IUniswapExchange exchange)
{
exchange = getUniswapExchangeFactoryContract().getExchange(tokenAddress);
address exchangeTokenAddress = fromTokenAddress;
// Whichever isn't WETH is the exchange token.
if (fromTokenAddress == address(getWethContract())) {
exchangeTokenAddress = toTokenAddress;
}
exchange = getUniswapExchangeFactoryContract().getExchange(exchangeTokenAddress);
require(address(exchange) != address(0), "NO_UNISWAP_EXCHANGE_FOR_TOKEN");
return exchange;
}