add op_return parsing utilities

Signed-off-by: Gregory Hill <[email protected]>

contracts/Script.sol

@@ -17,6 +17,7 @@ library Script {
     bytes1 internal constant OP_CHECKLOCKTIMEVERIFY = 0xb1;
     bytes1 internal constant OP_DROP = 0x75;
     bytes1 internal constant OP_0 = 0x00;
+    bytes1 internal constant OP_RETURN = 0x6a;
 
     // EXCEPTION MESSAGES
     string internal constant ERR_INVALID_SIZE = 'Invalid size';
@@ -65,6 +66,19 @@ library Script {
         return toBytes20(script.slice(2, 20));
     }
 
+    function isOpReturn(bytes memory script) internal pure returns (bool) {
+        return script[0] == OP_RETURN;
+    }
+
+    function OpReturn(bytes memory script)
+        internal
+        pure
+        returns (bytes memory)
+    {
+        bytes memory output = script.slice(1, script.length - 1);
+        return output.slice(1, uint8(output[0]));
+    }
+
     // 04 9f7b2a5c b1 75 76 a9 14 371c20fb2e9899338ce5e99908e64fd30b789313 88 ac
     function isCLTV(bytes memory script)
         internal

contracts/ScriptDelegate.sol

@@ -38,6 +38,14 @@ contract ScriptDelegate {
         return script.P2SH();
     }
 
+    function isOpReturn(bytes memory script) public pure returns (bool) {
+        return script.isOpReturn();
+    }
+
+    function OpReturn(bytes memory script) public pure returns (bytes memory) {
+        return script.OpReturn();
+    }
+
     function isCLTV(bytes memory script)
         public
         pure

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@interlay/btc-relay-sol",
-  "version": "0.3.9",
+  "version": "0.3.10",
   "description": "BTC Relay in Solidity",
   "main": "dist/index.js",
   "types": "dist/index.d.ts",

test/parser.test.ts

@@ -65,4 +65,18 @@ describe('Parser', () => {
     const result = await parser.extractOutputValueAtIndex(p2pkhTx, 1);
     expect(result.toNumber()).to.eq(139296477262);
   });
+
+  const p2wpkhTx =
+    '0x01000000000101747c038ceb0a5ab9edd61d39f3d3c611cd52ccd0f519d9ad93ccf1f81a0f' +
+    'c5d30100000000ffffffff026400000000000000160014867a55207369ad0fe47cf3cfd2ecba' +
+    'ef2446c8b40000000000000000226a2000000000000000000000000000000000000000000000' +
+    '0000000000000000000002473044022049a2913d41700d3076cec041d1d0906fe59c6d384c4a' +
+    'c4e67dc2b9bdc121f300022045a0c6edb241c39b2578bc9c2cb60e60821f18e273da799010bc' +
+    'c2a47c3d7e4e01210290465bd783baaa9d52df3b57e31cef7df72c0cbd10afe6a10e3cfbd947' +
+    '7c8acf00000000';
+
+  it('should successfully extract p2wpkh output', async () => {
+    const result = await parser.extractOutputScriptAtIndex(p2wpkhTx, 1);
+    console.log(result);
+  });
 });

test/scripts.test.ts

@@ -85,4 +85,19 @@ describe('Scripts', () => {
       'tb1q2krsjrpj3z6xm7xvj2xxjy9gcxa755y0exegh6'
     );
   });
+
+  it('should accept op_return', async () => {
+    const result = await parser.isOpReturn(
+      '0x6a200000000000000000000000000000000000000000000000000000000000000000'
+    );
+    expect(result).to.be.true;
+
+    const data = await parser.OpReturn(
+      '0x6a200000000000000000000000000000000000000000000000000000000000000000'
+    );
+
+    expect(data).to.eq(
+      '0x0000000000000000000000000000000000000000000000000000000000000000'
+    );
+  });
 });