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authorRemco Bloemen <remco@wicked.ventures>2018-06-26 03:21:15 +0800
committerAmir Bandeali <abandeali1@gmail.com>2018-06-27 03:23:19 +0800
commit4caf1271e42cea743cb24a93bbf832982e656cb2 (patch)
tree67b23f2fa72146b94e4adef6ac80d2bd429e13cc /packages/contracts/src
parent6921943afffa4a8588e652caf194ce5abb3976e1 (diff)
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Golf ERC721 transferFrom
Diffstat (limited to 'packages/contracts/src')
-rw-r--r--packages/contracts/src/contracts/current/protocol/AssetProxy/MixinERC721Transfer.sol168
-rw-r--r--packages/contracts/src/contracts/current/protocol/AssetProxy/libs/LibTransferErrors.sol1
2 files changed, 166 insertions, 3 deletions
diff --git a/packages/contracts/src/contracts/current/protocol/AssetProxy/MixinERC721Transfer.sol b/packages/contracts/src/contracts/current/protocol/AssetProxy/MixinERC721Transfer.sol
index c170917ea..e00e43889 100644
--- a/packages/contracts/src/contracts/current/protocol/AssetProxy/MixinERC721Transfer.sol
+++ b/packages/contracts/src/contracts/current/protocol/AssetProxy/MixinERC721Transfer.sol
@@ -19,17 +19,179 @@
pragma solidity ^0.4.24;
pragma experimental ABIEncoderV2;
+import "./mixins/MAuthorizable.sol";
import "../../utils/LibBytes/LibBytes.sol";
-import "../../tokens/ERC721Token/ERC721Token.sol";
import "./libs/LibTransferErrors.sol";
contract MixinERC721Transfer is
- LibTransferErrors
+ LibTransferErrors,
+ MAuthorizable
{
using LibBytes for bytes;
bytes4 constant SAFE_TRANSFER_FROM_SELECTOR = bytes4(keccak256("safeTransferFrom(address,address,uint256,bytes)"));
-
+ /// @dev Internal version of `transferFrom`.
+ /// @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 transferFrom(
+ bytes assetData,
+ address from,
+ address to,
+ uint256 amount
+ )
+ external
+ onlyAuthorized()
+ {
+ // `transferFrom`.
+ // The function is marked `external`, so no abi decodeding is done for
+ // us. Instead, we expect the `calldata` memory to contain the
+ // following:
+ //
+ // | Area | Offset | Length | Contents |
+ // |----------|--------|---------|-------------------------------------|
+ // | Header | 0 | 4 | function selector |
+ // | Params | | 4 * 32 | function parameters: |
+ // | | 4 | | 1. offset to assetData (*) |
+ // | | 36 | | 2. from |
+ // | | 68 | | 3. to |
+ // | | 100 | | 4. amount |
+ // | Data | | | assetData: |
+ // | | 132 | 32 | assetData Length |
+ // | | 164 | ** | assetData Contents |
+ //
+ // (*): offset is computed from start of function parameters, so offset
+ // by an additional 4 bytes in the calldata.
+ //
+ // WARNING: The ABIv2 specification allows additional padding between
+ // the Params and Data section. This will result in a larger
+ // offset to assetData.
+
+ // Asset data itself is encoded as follows:
+ //
+ // | Area | Offset | Length | Contents |
+ // |----------|--------|---------|-------------------------------------|
+ // | Header | 0 | 4 | function selector |
+ // | Params | | 3 * 32 | function parameters: |
+ // | | 4 | 12 + 20 | 1. token address |
+ // | | 36 | | 2. tokenId |
+ // | | 68 | | 3. offset to receiverData (*) |
+ // | Data | | | receiverData: |
+ // | | 100 | 32 | receiverData Length |
+ // | | 132 | ** | receiverData Contents |
+
+ // We construct calldata for the `token.safeTransferFrom` ABI.
+ // The layout of this calldata is in the table below.
+ //
+ // | Area | Offset | Length | Contents |
+ // |----------|--------|---------|-------------------------------------|
+ // | Header | 0 | 4 | function selector |
+ // | Params | | 4 * 32 | function parameters: |
+ // | | 4 | | 1. from |
+ // | | 36 | | 2. to |
+ // | | 68 | | 3. tokenId |
+ // | | 100 | | 4. offset to receiverData (*) |
+ // | Data | | | receiverData: |
+ // | | 132 | 32 | receiverData Length |
+ // | | 164 | ** | receiverData Contents |
+
+ // bytes4 safeTransferFromSelector = SAFE_TRANSFER_FROM_SELECTOR;
+ // bool success;
+ assembly {
+ // There exists only 1 of each token.
+ // require(amount == 1, "INVALID_AMOUNT")
+ if sub(calldataload(100), 1) {
+ // Revert with `Error("INVALID_AMOUNT")`
+ mstore(0, 0x08c379a000000000000000000000000000000000000000000000000000000000)
+ mstore(32, 0x0000002000000000000000000000000000000000000000000000000000000000)
+ mstore(64, 0x0000000e494e56414c49445f414d4f554e540000000000000000000000000000)
+ mstore(96, 0)
+ revert(0, 100)
+ }
+
+ // Require assetData to be at least 132 bytes
+ let offset := calldataload(4)
+ if lt(calldataload(add(offset, 4)), 132) {
+ // Revert with `Error("ASSET_DATA_TO_SHORT")`
+ mstore(0, 0x08c379a000000000000000000000000000000000000000000000000000000000)
+ mstore(32, 0x0000002000000000000000000000000000000000000000000000000000000000)
+ mstore(64, 0x0000001341535345545f444154415f544f5f53484f5254000000000000000000)
+ mstore(96, 0)
+ revert(0, 100)
+ }
+
+ /////// Setup State ///////
+ // `cdStart` is the start of the calldata for
+ // `token.safeTransferFrom` (equal to free memory ptr).
+ let cdStart := mload(64)
+ // `dataAreaLength` is the total number of words
+ // needed to store `receiverData`
+ // As-per the ABI spec, this value is padded up to
+ // the nearest multiple of 32,
+ // and includes 32-bytes for length.
+ // It's calculated as folows:
+ // - Unpadded length in bytes = `mload(receiverData) + 32`
+ // - Add 31 to convert rounding down to rounding up.
+ // Combined with the previous and this is `63`.
+ // - Round down to nearest multiple of 32 by clearing
+ // bits 0x1F. This is done with `and` and a mask.
+
+ /////// Setup Header Area ///////
+ // This area holds the 4-byte `transferFromSelector`.
+ // Any trailing data in transferFromSelector will be
+ // overwritten in the next `mstore` call.
+ mstore(cdStart, 0xb88d4fde00000000000000000000000000000000000000000000000000000000)
+
+ /////// Setup Params Area ///////
+ // Each parameter is padded to 32-bytes.
+ // The entire Params Area is 128 bytes.
+ // Notes:
+ // 1. A 20-byte mask is applied to addresses
+ // to zero-out the unused bytes.
+ // 2. The offset to `receiverData` is the length
+ // of the Params Area (128 bytes).
+
+ let length := calldataload(add(offset, 104))
+ let token := calldataload(add(offset, 40))
+
+ // Round length up to multiple of 32
+ length := and(add(length, 31), 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFE0)
+
+ // Copy `from` and `to`
+ calldatacopy(add(cdStart, 4), 36, 64)
+
+ // TokenId
+ mstore(add(cdStart, 68), calldataload(add(offset, 72)))
+
+ // Offset to receiverData
+ mstore(add(cdStart, 100), 128)
+
+ // receiverData (including length)
+ calldatacopy(add(cdStart, 132), add(offset, 104), add(length, 32))
+
+ /////// Call `token.safeTransferFrom` using the calldata ///////
+ let success := call(
+ gas, // forward all gas
+ token, // call address of token contract
+ 0, // don't send any ETH
+ cdStart, // pointer to start of input
+ add(length, 164), // length of input
+ 0, // write output to null
+ 0 // output size is 0 bytes
+ )
+
+ if iszero(success) {
+ // Revert with `Error("TRANSFER_FAILED")`
+ mstore(0, 0x08c379a000000000000000000000000000000000000000000000000000000000)
+ mstore(32, 0x0000002000000000000000000000000000000000000000000000000000000000)
+ mstore(64, 0x0000000f5452414e534645525f4641494c454400000000000000000000000000)
+ mstore(96, 0)
+ revert(0, 100)
+ }
+ }
+ }
+
/// @dev Internal version of `transferFrom`.
/// @param assetData Encoded byte array.
/// @param from Address to transfer asset from.
diff --git a/packages/contracts/src/contracts/current/protocol/AssetProxy/libs/LibTransferErrors.sol b/packages/contracts/src/contracts/current/protocol/AssetProxy/libs/LibTransferErrors.sol
index 88187f196..98bca31b2 100644
--- a/packages/contracts/src/contracts/current/protocol/AssetProxy/libs/LibTransferErrors.sol
+++ b/packages/contracts/src/contracts/current/protocol/AssetProxy/libs/LibTransferErrors.sol
@@ -25,4 +25,5 @@ contract LibTransferErrors {
/// Transfer errors ///
string constant INVALID_AMOUNT = "INVALID_AMOUNT"; // Transfer amount must equal 1.
string constant TRANSFER_FAILED = "TRANSFER_FAILED"; // Transfer failed.
+ string constant ASSET_DATA_TO_SHORT = "ASSET_DATA_TO_SHORT"; // Asset data to short
}