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Factor offsets into calldata locations

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This commit is contained in:
Amir Bandeali
2018-11-11 20:08:24 -08:00
parent 8b80d28029
commit 037e63ab49
2 changed files with 57 additions and 20 deletions
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68
packages/contracts/contracts/protocol/AssetProxy/MultiAssetProxy.sol
View File

@@ -49,7 +49,7 @@ contract MultiAssetProxy is
// To lookup a value in a mapping, we load from the storage location keccak256(k, p),
// where k is the key left padded to 32 bytes and p is the storage slot
mstore(0, and(caller, 0xffffffffffffffffffffffffffffffffffffffff))
mstore(0, caller)
mstore(32, authorized_slot)
// Revert if authorized[msg.sender] == false
@@ -63,7 +63,7 @@ contract MultiAssetProxy is
}
// `transferFrom`.
// The function is marked `external`, so no abi decodeding is done for
// The function is marked `external`, so no abi decoding is done for
// us. Instead, we expect the `calldata` memory to contain the
// following:
//
@@ -107,20 +107,43 @@ contract MultiAssetProxy is
// | | 132 + a | b | nestedAssetData Contents (offsets) |
// | | 132 + a + b | | nestedAssetData[0, ..., len] |
// Load offset to `amounts`
// We must add 4 (function selector) + 32 (assetData len) + 4 (assetProxyId) to the assetData offset
// In order to find the offset to `amounts`, we must add:
// 4 (function selector)
// + assetDataOffset
// + 32 (assetData len)
// + 4 (assetProxyId)
let amountsOffset := calldataload(add(assetDataOffset, 40))
// Load offsets to `nestedAssetData`
// In order to find the offset to `nestedAssetData`, we must add:
// 4 (function selector)
// + assetDataOffset
// + 32 (assetData len)
// + 4 (assetProxyId)
// + 32 (amounts offset)
let nestedAssetDataOffset := calldataload(add(assetDataOffset, 72))
// In order to find the start of the `amounts` contents, we must add:
// 4 (function selector)
// + assetDataOffset
// + 32 (assetData len)
// + 4 (assetProxyId)
// + amountsOffset
// + 32 (amounts len)
let amountsContentsStart := add(assetDataOffset, add(amountsOffset, 72))
// Load number of elements in `amounts`
// We must add 4 (function selector) + 128 (4 params * 32) + 32 (assetData len) + 4 (assetProxyId) + 32 (amounts len) to the amounts offset
let amountsContentsStart := add(amountsOffset, 200)
let amountsLen := calldataload(sub(amountsContentsStart, 32))
// In order to find the start of the `nestedAssetData` contents, we must add:
// 4 (function selector)
// + assetDataOffset
// + 32 (assetData len)
// + 4 (assetProxyId)
// + nestedAssetDataOffset
// + 32 (nestedAssetData len)
let nestedAssetDataContentsStart := add(assetDataOffset, add(nestedAssetDataOffset, 72))
// Load number of elements in `nestedAssetData`
let nestedAssetDataContentsStart := add(nestedAssetDataOffset, 200)
let nestedAssetDataLen := calldataload(sub(nestedAssetDataContentsStart, 32))
// Revert if number of elements in `amounts` differs from number of elements in `nestedAssetData`
@@ -172,9 +195,20 @@ contract MultiAssetProxy is
// Load offset to `nestedAssetData[i]`
let nestedAssetDataElementOffset := calldataload(add(nestedAssetDataContentsStart, i))
// In order to find the start of the `nestedAssetData[i]` contents, we must add:
// 4 (function selector)
// + assetDataOffset
// + 32 (assetData len)
// + 4 (assetProxyId)
// + nestedAssetDataOffset
// + 32 (nestedAssetData len)
// + nestedAssetDataElementOffset
// + 32 (nestedAssetDataElement len)
let nestedAssetDataElementContentsStart := add(assetDataOffset, add(nestedAssetDataOffset, add(nestedAssetDataElementOffset, 104)))
// Load length of `nestedAssetData[i]`
let nestedAssetDataElementContentsStart := add(nestedAssetDataElementOffset, 264)
let nestedAssetDataElementLen := calldataload(sub(nestedAssetDataElementContentsStart, 32))
let nestedAssetDataElementLenStart := sub(nestedAssetDataElementContentsStart, 32)
let nestedAssetDataElementLen := calldataload(nestedAssetDataElementLenStart)
// Revert if the `nestedAssetData` does not contain a 4 byte `assetProxyId`
if lt(nestedAssetDataElementLen, 4) {
@@ -208,7 +242,7 @@ contract MultiAssetProxy is
// Copy `nestedAssetData[i]` from calldata to memory
calldatacopy(
132, // memory slot after `amounts[i]`
nestedAssetDataElementOffset, // location of `nestedAssetData[i]` in calldata
nestedAssetDataElementLenStart, // location of `nestedAssetData[i]` in calldata
add(nestedAssetDataElementLen, 32) // `nestedAssetData[i].length` plus 32 byte length
)
@@ -219,12 +253,18 @@ contract MultiAssetProxy is
0, // don't send any ETH
0, // pointer to start of input
add(164, nestedAssetDataElementLen), // length of input
100, // write output over memory that won't be reused
512 // reserve 512 bytes for output
0, // write output over memory that won't be reused
0 // reserve 512 bytes for output
)
// Revert with reason given by AssetProxy if `transferFrom` call failed
if iszero(success) {
revert(100, returndatasize())
returndatacopy(
0, // copy to memory at 0
0, // copy from return data at 0
returndatasize() // copy all return data
)
revert(0, returndatasize())
}
}

9
packages/contracts/contracts/protocol/AssetProxy/interfaces/IAssetData.sol
View File

@@ -27,21 +27,18 @@ pragma experimental ABIEncoderV2;
interface IAssetData {
function ERC20Token(address tokenContract)
external
pure;
external;
function ERC721Token(
address tokenContract,
uint256 tokenId
)
external
pure;
external;
function MultiAsset(
uint256[] amounts,
bytes[] nestedAssetData
)
external
pure;
external;
}