staking: refactor address from pub key function and add test for uncompressed key (#225)

Author: abarmat

contracts/Staking.sol

@@ -633,20 +633,30 @@ contract Staking is Governed {
 
         // Only allocations with a token amount are allowed
         require(_tokens > 0, "Allocation: cannot allocate zero tokens");
+
         // Need to have tokens in our stake to be able to allocate
         require(indexerStake.hasTokens(), "Allocation: indexer has no stakes");
+
         // Need to have free capacity not used for other purposes to allocate
         require(
             getIndexerCapacity(indexer) >= _tokens,
             "Allocation: not enough tokens available to allocate"
         );
+
         // Can only allocate tokens to a SubgraphDeployment if not currently allocated
         require(
             indexerStake.hasAllocation(_subgraphDeploymentID) == false,
             "Allocation: cannot allocate if already allocated"
         );
+
+        // Channel public key must be in uncompressed format
+        require(
+            uint8(_channelPubKey[0]) == 4 && _channelPubKey.length == 65,
+            "Allocation: invalid channel public key"
+        );
+
         // Cannot reuse a channelID that has been used in the past
-        address channelID = publicKeyToAddress(bytes(_channelPubKey[1:])); // solium-disable-line
+        address channelID = address(uint256(keccak256(bytes(_channelPubKey[1:])))); // solium-disable-line
         require(isChannel(channelID) == false, "Allocation: channel ID already in use");
 
         // Allocate and setup channel
@@ -969,15 +979,4 @@ contract Staking is Governed {
         }
         return id;
     }
-
-    /**
-     * @dev Convert an uncompressed public key to an Ethereum address
-     * @param _publicKey Public key in uncompressed format without the 1 byte prefix
-     * @return An Ethereum address corresponding to the public key
-     */
-    function publicKeyToAddress(bytes memory _publicKey) private pure returns (address) {
-        uint256 mask = 2**(8 * 21) - 1;
-        uint256 value = uint256(keccak256(_publicKey));
-        return address(value & mask);
-    }
 }

test/staking/general.test.ts

@@ -1,6 +1,6 @@
 import { expect, use } from 'chai'
 import { Event, Wallet } from 'ethers'
-import { BigNumber } from 'ethers/utils'
+import { computePublicKey, BigNumber } from 'ethers/utils'
 import { AddressZero } from 'ethers/constants'
 import { solidity } from 'ethereum-waffle'
 
@@ -526,6 +526,20 @@ describe('Staking', () => {
           await expect(tx).to.be.revertedWith('Allocation: cannot allocate zero tokens')
         })
 
+        it('reject allocate with invalid public key', async function() {
+          const invalidChannelPubKey = computePublicKey(channelPubKey, true)
+          const tx = staking
+            .connect(indexer)
+            .allocate(
+              subgraphDeploymentID,
+              toGRT('100'),
+              invalidChannelPubKey,
+              channelProxy.address,
+              price,
+            )
+          await expect(tx).to.be.revertedWith('Allocation: invalid channel public key')
+        })
+
         context('> when allocated', function() {
           beforeEach(async function() {
             await allocate(toGRT('10'))