Golf the authorization check
This commit is contained in:
Remco Bloemen
committed by
Amir Bandeali
Amir Bandeali
parent
b79588c4a0
commit
394fbebfa8
@@ -31,7 +31,7 @@ contract ERC20Proxy is
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{
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// Id of this proxy.
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bytes4 constant PROXY_ID = bytes4(keccak256("ERC20Token(address)"));
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/// @dev Gets the proxy id associated with the proxy address.
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/// @return Proxy id.
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function getProxyId()
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@@ -41,4 +41,135 @@ contract ERC20Proxy is
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{
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return PROXY_ID;
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}
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/// @dev Internal version of `transferFrom`.
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/// @param assetData Encoded byte array.
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/// @param from Address to transfer asset from.
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/// @param to Address to transfer asset to.
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/// @param amount Amount of asset to transfer.
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function transferFrom(
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bytes assetData,
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address from,
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address to,
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uint256 amount
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)
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external
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{
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bool auth = authorized[msg.sender];
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// `transferFrom`.
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// The function is marked `external`, so no abi decodeding is done for
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// us. Instead, we expect the `calldata` memory to contain the
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// following:
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//
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// | Area | Offset | Length | Contents |
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// |----------|--------|---------|-------------------------------------|
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// | Header | 0 | 4 | function selector |
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// | Params | | 4 * 32 | function parameters: |
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// | | 4 | | 1. offset to assetData (*) |
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// | | 36 | | 2. from |
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// | | 68 | | 3. to |
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// | | 100 | | 4. amount |
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// | Data | | | assetData: |
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// | | 132 | 32 | assetData Length |
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// | | 164 | ** | assetData Contents |
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//
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// (*): offset is computed from start of function parameters, so offset
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// by an additional 4 bytes in the calldata.
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//
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// WARNING: The ABIv2 specification allows additional padding between
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// the Params and Data section. This will result in a larger
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// offset to assetData.
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// Asset data itself is encoded as follows:
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//
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// | Area | Offset | Length | Contents |
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// |----------|--------|---------|-------------------------------------|
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// | Header | 0 | 4 | function selector |
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// | Params | | 1 * 32 | function parameters: |
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// | | 4 | 12 + 20 | 1. token address |
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// Transfer tokens.
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// We do a raw call so we can check the success separate
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// from the return data.
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// We construct calldata for the `token.transferFrom` ABI.
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// The layout of this calldata is in the table below.
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//
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// | Area | Offset | Length | Contents |
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// |----------|--------|---------|-------------------------------------|
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// | Header | 0 | 4 | function selector |
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// | Params | | 3 * 32 | function parameters: |
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// | | 4 | | 1. from |
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// | | 36 | | 2. to |
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// | | 68 | | 3. amount |
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assembly {
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if iszero(auth) {
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// Revert with `Error("SENDER_NOT_AUTHORIZED")`
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mstore(0, 0x08c379a000000000000000000000000000000000000000000000000000000000)
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mstore(32, 0x0000002000000000000000000000000000000000000000000000000000000000)
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mstore(64, 0x0000001553454e4445525f4e4f545f415554484f52495a454400000000000000)
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mstore(96, 0)
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revert(0, 100)
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}
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/////// Token contract address ///////
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// The token address is found as follows:
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// * It is stored at offset 4 in `assetData` contents.
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// * This is stored at offset 32 from `assetData`.
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// * The offset to `assetData` from Params is stored at offset
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// 4 in calldata.
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// * The offset of Params in calldata is 4.
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// So we read location 4 and add 32 + 4 + 4 to it.
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let token := calldataload(add(calldataload(4), 40))
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/////// Setup Header Area ///////
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// This area holds the 4-byte `transferFrom` selector.
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// Any trailing data in transferFromSelector will be
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// overwritten in the next `mstore` call.
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mstore(0, 0x23b872dd00000000000000000000000000000000000000000000000000000000)
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/////// Setup Params Area ///////
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// We copy the fields `from`, `to` and `amount` in bulk
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// from our own calldata to the new calldata.
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calldatacopy(4, 36, 96)
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/////// Call `token.transferFrom` using the calldata ///////
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let success := call(
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gas, // forward all gas
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token, // call address of token contract
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0, // don't send any ETH
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0, // pointer to start of input
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100, // length of input
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0, // write output over input
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32 // output size should be 32 bytes
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)
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/////// Check return data. ///////
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// If there is no return data, we assume the token incorrectly
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// does not return a bool. In this case we expect it to revert
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// on failure, which was handled above.
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// If the token does return data, we require that it is a single
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// nonzero 32 bytes value.
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// So the transfer succeeded if the call succeeded and either
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// returned nothing, or returned a non-zero 32 byte value.
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success := and(success, or(
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iszero(returndatasize),
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and(
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eq(returndatasize, 32),
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gt(mload(0), 0)
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)
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))
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if success {
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return(0, 0)
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}
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// Revert with `Error("TRANSFER_FAILED")`
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mstore(0, 0x08c379a000000000000000000000000000000000000000000000000000000000)
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mstore(32, 0x0000002000000000000000000000000000000000000000000000000000000000)
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mstore(64, 0x0000000f5452414e534645525f4641494c454400000000000000000000000000)
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mstore(96, 0)
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revert(0, 100)
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}
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}
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}
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@@ -27,127 +27,6 @@ contract MixinERC20Transfer is
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MAuthorizable
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{
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using LibBytes for bytes;
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/// @dev Internal version of `transferFrom`.
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/// @param assetData Encoded byte array.
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/// @param from Address to transfer asset from.
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/// @param to Address to transfer asset to.
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/// @param amount Amount of asset to transfer.
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function transferFrom(
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bytes assetData,
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address from,
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address to,
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uint256 amount
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)
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external
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onlyAuthorized()
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{
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// `transferFrom`.
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// The function is marked `external`, so no abi decodeding is done for
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// us. Instead, we expect the `calldata` memory to contain the
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// following:
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//
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// | Area | Offset | Length | Contents |
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// |----------|--------|---------|-------------------------------------|
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// | Header | 0 | 4 | function selector |
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// | Params | | 4 * 32 | function parameters: |
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// | | 4 | | 1. offset to assetData (*) |
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// | | 36 | | 2. from |
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// | | 68 | | 3. to |
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// | | 100 | | 4. amount |
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// | Data | | | assetData: |
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// | | 132 | 32 | assetData Length |
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// | | 164 | ** | assetData Contents |
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//
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// (*): offset is computed from start of function parameters, so offset
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// by an additional 4 bytes in the calldata.
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//
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// WARNING: The ABIv2 specification allows additional padding between
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// the Params and Data section. This will result in a larger
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// offset to assetData.
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// Asset data itself is encoded as follows:
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//
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// | Area | Offset | Length | Contents |
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// |----------|--------|---------|-------------------------------------|
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// | Header | 0 | 4 | function selector |
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// | Params | | 1 * 32 | function parameters: |
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// | | 4 | 12 + 20 | 1. token address |
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// Transfer tokens.
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// We do a raw call so we can check the success separate
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// from the return data.
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// We construct calldata for the `token.transferFrom` ABI.
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// The layout of this calldata is in the table below.
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//
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// | Area | Offset | Length | Contents |
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// |----------|--------|---------|-------------------------------------|
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// | Header | 0 | 4 | function selector |
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// | Params | | 3 * 32 | function parameters: |
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// | | 4 | | 1. from |
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// | | 36 | | 2. to |
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// | | 68 | | 3. amount |
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assembly {
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/////// Token contract address ///////
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// The token address is found as follows:
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// * It is stored at offset 4 in `assetData` contents.
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// * This is stored at offset 32 from `assetData`.
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// * The offset to `assetData` from Params is stored at offset
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// 4 in calldata.
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// * The offset of Params in calldata is 4.
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// So we read location 4 and add 32 + 4 + 4 to it.
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let token := calldataload(add(calldataload(4), 40))
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/////// Setup Header Area ///////
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// This area holds the 4-byte `transferFrom` selector.
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// Any trailing data in transferFromSelector will be
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// overwritten in the next `mstore` call.
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mstore(0, 0x23b872dd00000000000000000000000000000000000000000000000000000000)
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/////// Setup Params Area ///////
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// We copy the fields `from`, `to` and `amount` in bulk
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// from our own calldata to the new calldata.
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calldatacopy(4, 36, 96)
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/////// Call `token.transferFrom` using the calldata ///////
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let success := call(
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gas, // forward all gas
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token, // call address of token contract
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0, // don't send any ETH
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0, // pointer to start of input
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100, // length of input
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0, // write output over input
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32 // output size should be 32 bytes
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)
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/////// Check return data. ///////
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// If there is no return data, we assume the token incorrectly
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// does not return a bool. In this case we expect it to revert
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// on failure, which was handled above.
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// If the token does return data, we require that it is a single
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// nonzero 32 bytes value.
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// So the transfer succeeded if the call succeeded and either
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// returned nothing, or returned a non-zero 32 byte value.
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success := and(success, or(
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iszero(returndatasize),
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and(
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eq(returndatasize, 32),
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gt(mload(0), 0)
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)
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))
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if success {
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return(0, 0)
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}
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// Revert with `Error("TRANSFER_FAILED")`
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mstore(0, 0x08c379a000000000000000000000000000000000000000000000000000000000)
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mstore(32, 0x0000002000000000000000000000000000000000000000000000000000000000)
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mstore(64, 0x0000000f5452414e534645525f4641494c454400000000000000000000000000)
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mstore(96, 0)
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revert(0, 100)
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}
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}
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/// @dev Internal version of `transferFrom`.
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/// @param assetData Encoded byte array.
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