Merge pull request #38 from Once-Upon/benguyen0214/ou-1152-token-airdrop

Token airdrop
Once-Upon · Dec 5, 2023 · 3e58764 · 3e58764
2 parents cdb81fa + 8703f01
commit 3e58764
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Showing 3 changed files with 39 additions and 27 deletions.
diff --git a/src/helpers/constants.ts b/src/helpers/constants.ts
@@ -14,8 +14,6 @@ export const TOKEN_SWAP_CONTRACTS = [
   '0xdef1c0ded9bec7f1a1670819833240f027b25eff', // 0x Exchange Proxy. NOTE - This is both an erc20 swap and erc721 swap contract. This address is in both contract lists.
 ];
 
-export const AIRDROP_THRESHOLD = 10;
-
 export const KNOWN_ADDRESSES = {
   NULL: '0x0000000000000000000000000000000000000000',
   WETH: '0xc02aaa39b223fe8d0a0e5c4f27ead9083c756cc2',

diff --git a/src/heuristics/tokenAirdrop/tokenAirdrop.spec.ts b/src/heuristics/tokenAirdrop/tokenAirdrop.spec.ts
@@ -2,7 +2,6 @@ import { Transaction } from '../../types';
 import { detectTokenAirdrop } from './tokenAirdrop';
 import tokenAirdrop0x9559fbd9 from '../../test/transactions/tokenAirdrop-0x9559fbd9.json';
 import tokenAirdrop0xe2a9a20b from '../../test/transactions/tokenAirdrop-0xe2a9a20b.json';
-import tokenAirdrop0x4c7af9a2 from '../../test/transactions/tokenAirdrop-0x4c7af9a2.json';
 import tokenAirdrop0xb312ecc2 from '../../test/transactions/tokenAirdrop-0xb312ecc2.json';
 import catchall0xc35c01ac from '../../test/transactions/catchall-0xc35c01ac.json';
 
@@ -19,14 +18,9 @@ describe('Token Airdrop', () => {
     expect(tokenAirdrop2).toBe(true);
 
     const tokenAirdrop3 = detectTokenAirdrop(
-      tokenAirdrop0x4c7af9a2 as Transaction,
-    );
-    expect(tokenAirdrop3).toBe(true);
-
-    const tokenAirdrop4 = detectTokenAirdrop(
       tokenAirdrop0xb312ecc2 as Transaction,
     );
-    expect(tokenAirdrop4).toBe(true);
+    expect(tokenAirdrop3).toBe(true);
   });
 
   it('Should not detect token airdrop transaction', () => {

diff --git a/src/heuristics/tokenAirdrop/tokenAirdrop.ts b/src/heuristics/tokenAirdrop/tokenAirdrop.ts
@@ -1,5 +1,7 @@
 import { Transaction } from '../../types';
-import { AIRDROP_THRESHOLD, KNOWN_ADDRESSES } from '../../helpers/constants';
+import { KNOWN_ADDRESSES } from '../../helpers/constants';
+
+const AIRDROP_THRESHOLD = 10;
 
 export function tokenAirdropContextualizer(
   transaction: Transaction,
@@ -10,6 +12,13 @@ export function tokenAirdropContextualizer(
   return generateTokenAirdropContext(transaction);
 }
 
+/**
+ * Detection criteria
+ *
+ * Only 1 address in netAssetTransfers is sending, all other addresses are receiving. It's ok if the only sending address is the null (airdrop via mints)
+ * All assets sent are the same asset (contract address)
+ * There are more than AIRDROP_THRESHOLD number of receivers. A receiver can receive more than one airdrop.
+ */
 export function detectTokenAirdrop(transaction: Transaction): boolean {
   /**
    * There is a degree of overlap between the 'detect' and 'generateContext' functions,
@@ -21,28 +30,39 @@ export function detectTokenAirdrop(transaction: Transaction): boolean {
     return false;
   }
 
-  const airdropTracker: Record<
-    string,
-    { amount: number; assetTransfers: Set<any> }
-  > = {};
-
-  for (const assetTransfer of transaction.assetTransfers) {
-    const transferKey = `${assetTransfer.from}-${assetTransfer.asset}-${assetTransfer.type}`;
-    if (!airdropTracker[transferKey]) {
-      airdropTracker[transferKey] = {
-        amount: 0,
-        assetTransfers: new Set(),
-      };
+  // check if only 1 address is sending
+  const sendAddresses = Object.keys(transaction.netAssetTransfers).filter(
+    (address) => transaction.netAssetTransfers[address].sent.length > 0,
+  );
+  if (sendAddresses.length > 1) {
+    return false;
+  }
+  // check if all other addresses are receiving
+  for (const address in transaction.netAssetTransfers) {
+    if (address === sendAddresses[0]) {
+      continue;
     }
-    airdropTracker[transferKey].amount++;
-    airdropTracker[transferKey].assetTransfers.add(assetTransfer);
 
-    if (airdropTracker[transferKey].amount > AIRDROP_THRESHOLD) {
-      return true;
+    const sent = transaction.netAssetTransfers[address]?.sent;
+    const received = transaction.netAssetTransfers[address]?.received;
+    if (sent?.length || !received?.length) {
+      return false;
     }
   }
+  // check if all assets sent are the same contract
+  const assetsSent = transaction.netAssetTransfers[sendAddresses[0]].sent;
+  if (!assetsSent.every((ele) => ele.asset === assetsSent[0].asset)) {
+    return false;
+  }
+  // check if there are more than AIRDROP_THRESHOLD number of receivers
+  if (
+    Object.keys(transaction.netAssetTransfers).length - 1 <
+    AIRDROP_THRESHOLD
+  ) {
+    return false;
+  }
 
-  return false;
+  return true;
 }
 
 function generateTokenAirdropContext(transaction: Transaction): Transaction {