Merge #17204: wallet: Do not turn OP_1NEGATE in scriptSig into 0x0181 in signing code (sipa)

dca2863 test: ensure OP_1NEGATE satisfies BIP62 minimal push rule (Jon Atack)
e629d07 Do not turn OP_1NEGATE in scriptSig into 0x0181 in signing code (Pieter Wuille)

Pull request description:

  A rebase of #13084 which additionally modifies the test code (unaddressed in the original, assuming sipa is too busy to deal with this at the moment).

  Relatively simple bugfix so it'd be good to have merged soon.

  Turning OP_1NEGATE into 0x0181 results in a larger-than-necessary data push instead of just actually using the OP_1NEGATE opcode (0x4f). This fails the minimal push rule of BIP 62 and makes the result non-standard.

ACKs for top commit:
  fjahr:
    Code review ACK dca2863
  luke-jr:
    ACK dca2863
  jonatack:
    ACK dca2863

Tree-SHA512: 706d9a2ef20c809dea923e477a873e2fd60db8d0ae64289e510b766a38005c1f31ab0b5883f16b9c7863ff0d3f705e8e413f6121320028ac196b79c3184a4113

Author: laanwj

src/script/sign.cpp

@@ -186,6 +186,8 @@ static CScript PushAll(const std::vector<valtype>& values)
             result << OP_0;
         } else if (v.size() == 1 && v[0] >= 1 && v[0] <= 16) {
             result << CScript::EncodeOP_N(v[0]);
+        } else if (v.size() == 1 && v[0] == 0x81) {
+            result << OP_1NEGATE;
         } else {
             result << v;
         }

src/test/transaction_tests.cpp

@@ -361,6 +361,8 @@ static CScript PushAll(const std::vector<valtype>& values)
             result << OP_0;
         } else if (v.size() == 1 && v[0] >= 1 && v[0] <= 16) {
             result << CScript::EncodeOP_N(v[0]);
+        } else if (v.size() == 1 && v[0] == 0x81) {
+            result << OP_1NEGATE;
         } else {
             result << v;
         }

test/functional/rpc_signrawtransaction.py

@@ -198,10 +198,30 @@ def verify_txn_with_witness_script(self, tx_type):
         assert_equal(spending_tx_signed['complete'], True)
         self.nodes[0].sendrawtransaction(spending_tx_signed['hex'])
 
+    def OP_1NEGATE_test(self):
+        self.log.info("Test OP_1NEGATE (0x4f) satisfies BIP62 minimal push standardness rule")
+        hex_str = (
+            "0200000001FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF"
+            "FFFFFFFF00000000044F024F9CFDFFFFFF01F0B9F5050000000023210277777777"
+            "77777777777777777777777777777777777777777777777777777777AC66030000"
+        )
+        prev_txs = [
+            {
+                "txid": "FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF",
+                "vout": 0,
+                "scriptPubKey": "A914AE44AB6E9AA0B71F1CD2B453B69340E9BFBAEF6087",
+                "redeemScript": "4F9C",
+                "amount": 1,
+            }
+        ]
+        txn = self.nodes[0].signrawtransactionwithwallet(hex_str, prev_txs)
+        assert txn["complete"]
+
     def run_test(self):
         self.successful_signing_test()
         self.script_verification_error_test()
         self.witness_script_test()
+        self.OP_1NEGATE_test()
         self.test_with_lock_outputs()