Merge #14890: rpc: Avoid creating non-standard raw transactions

fa4c8679ed rpc: Avoid creating non-standard raw transactions (MarcoFalke)

Pull request description:

  Multiple OP_RETURN outputs in a transaction are not standard and unlikely to be relayed, so avoid creating them.

  Apart from that, the logic was broken in that it duplicated the same hex-data for each data output: Closes #14868.

Tree-SHA512: b08d08062b5622e8a7b497e490ccaf53b06e844c863fda3bf3f932a98684a809e8341aeb98232059a795afb32d8770a6c5591a66f8e6ee372b672af245607887

src/rpc/rawtransaction.cpp

@@ -397,7 +397,6 @@ CMutableTransaction ConstructTransaction(const UniValue& inputs_in, const UniVal
         rawTx.vin.push_back(in);
     }
 
-    std::set<CTxDestination> destinations;
     if (!outputs_is_obj) {
         // Translate array of key-value pairs into dict
         UniValue outputs_dict = UniValue(UniValue::VOBJ);
@@ -413,8 +412,17 @@ CMutableTransaction ConstructTransaction(const UniValue& inputs_in, const UniVal
         }
         outputs = std::move(outputs_dict);
     }
+
+    // Duplicate checking
+    std::set<CTxDestination> destinations;
+    bool has_data{false};
+
     for (const std::string& name_ : outputs.getKeys()) {
         if (name_ == "data") {
+            if (has_data) {
+                throw JSONRPCError(RPC_INVALID_PARAMETER, "Invalid parameter, duplicate key: data");
+            }
+            has_data = true;
             std::vector<unsigned char> data = ParseHexV(outputs[name_].getValStr(), "Data");
 
             CTxOut out(0, CScript() << OP_RETURN << data);
@@ -466,7 +474,8 @@ static UniValue createrawtransaction(const JSONRPCRequest& request)
                                 },
                         },
                         },
-                    {"outputs", RPCArg::Type::ARR, /* opt */ false, /* default_val */ "", "a json array with outputs (key-value pairs).\n"
+                    {"outputs", RPCArg::Type::ARR, /* opt */ false, /* default_val */ "", "a json array with outputs (key-value pairs), where none of the keys are duplicated.\n"
+                            "That is, each address can only appear once and there can only be one 'data' object.\n"
                             "For compatibility reasons, a dictionary, which holds the key-value pairs directly, is also\n"
                             "                             accepted as second parameter.",
                         {
@@ -1608,7 +1617,8 @@ UniValue createpsbt(const JSONRPCRequest& request)
                                 },
                         },
                         },
-                    {"outputs", RPCArg::Type::ARR, /* opt */ false, /* default_val */ "", "a json array with outputs (key-value pairs).\n"
+                    {"outputs", RPCArg::Type::ARR, /* opt */ false, /* default_val */ "", "a json array with outputs (key-value pairs), where none of the keys are duplicated.\n"
+                            "That is, each address can only appear once and there can only be one 'data' object.\n"
                             "For compatibility reasons, a dictionary, which holds the key-value pairs directly, is also\n"
                             "                             accepted as second parameter.",
                         {

src/test/rpc_tests.cpp

@@ -129,9 +129,6 @@ BOOST_AUTO_TEST_CASE(rpc_createraw_op_return)
 {
     BOOST_CHECK_NO_THROW(CallRPC("createrawtransaction [{\"txid\":\"a3b807410df0b60fcb9736768df5823938b2f838694939ba45f3c0a1bff150ed\",\"vout\":0}] {\"data\":\"68656c6c6f776f726c64\"}"));
 
-    // Allow more than one data transaction output
-    BOOST_CHECK_NO_THROW(CallRPC("createrawtransaction [{\"txid\":\"a3b807410df0b60fcb9736768df5823938b2f838694939ba45f3c0a1bff150ed\",\"vout\":0}] {\"data\":\"68656c6c6f776f726c64\",\"data\":\"68656c6c6f776f726c64\"}"));
-
     // Key not "data" (bad address)
     BOOST_CHECK_THROW(CallRPC("createrawtransaction [{\"txid\":\"a3b807410df0b60fcb9736768df5823938b2f838694939ba45f3c0a1bff150ed\",\"vout\":0}] {\"somedata\":\"68656c6c6f776f726c64\"}"), std::runtime_error);
 

src/wallet/rpcwallet.cpp

@@ -4023,7 +4023,8 @@ UniValue walletcreatefundedpsbt(const JSONRPCRequest& request)
                             },
                         },
                         },
-                    {"outputs", RPCArg::Type::ARR, /* opt */ false, /* default_val */ "", "a json array with outputs (key-value pairs).\n"
+                    {"outputs", RPCArg::Type::ARR, /* opt */ false, /* default_val */ "", "a json array with outputs (key-value pairs), where none of the keys are duplicated.\n"
+                            "That is, each address can only appear once and there can only be one 'data' object.\n"
                             "For compatibility reasons, a dictionary, which holds the key-value pairs directly, is also\n"
                             "                             accepted as second parameter.",
                         {

test/functional/rpc_rawtransaction.py

@@ -100,6 +100,8 @@ class RawTransactionsTest(BitcoinTestFramework):
         assert_raises_rpc_error(-3, "Amount out of range", self.nodes[0].createrawtransaction, [], {address: -1})
         assert_raises_rpc_error(-8, "Invalid parameter, duplicated address: %s" % address, self.nodes[0].createrawtransaction, [], multidict([(address, 1), (address, 1)]))
         assert_raises_rpc_error(-8, "Invalid parameter, duplicated address: %s" % address, self.nodes[0].createrawtransaction, [], [{address: 1}, {address: 1}])
+        assert_raises_rpc_error(-8, "Invalid parameter, duplicate key: data", self.nodes[0].createrawtransaction, [], [{"data": 'aa'}, {"data": "bb"}])
+        assert_raises_rpc_error(-8, "Invalid parameter, duplicate key: data", self.nodes[0].createrawtransaction, [], multidict([("data", 'aa'), ("data", "bb")]))
         assert_raises_rpc_error(-8, "Invalid parameter, key-value pair must contain exactly one key", self.nodes[0].createrawtransaction, [], [{'a': 1, 'b': 2}])
         assert_raises_rpc_error(-8, "Invalid parameter, key-value pair not an object as expected", self.nodes[0].createrawtransaction, [], [['key-value pair1'], ['2']])
 
@@ -127,19 +129,12 @@ class RawTransactionsTest(BitcoinTestFramework):
             bytes_to_hex_str(tx.serialize()),
             self.nodes[2].createrawtransaction(inputs=[{'txid': txid, 'vout': 9}], outputs=[{address: 99}, {address2: 99}]),
         )
-        # Two data outputs
-        tx.deserialize(BytesIO(hex_str_to_bytes(self.nodes[2].createrawtransaction(inputs=[{'txid': txid, 'vout': 9}], outputs=multidict([('data', '99'), ('data', '99')])))))
-        assert_equal(len(tx.vout), 2)
-        assert_equal(
-            bytes_to_hex_str(tx.serialize()),
-            self.nodes[2].createrawtransaction(inputs=[{'txid': txid, 'vout': 9}], outputs=[{'data': '99'}, {'data': '99'}]),
-        )
         # Multiple mixed outputs
-        tx.deserialize(BytesIO(hex_str_to_bytes(self.nodes[2].createrawtransaction(inputs=[{'txid': txid, 'vout': 9}], outputs=multidict([(address, 99), ('data', '99'), ('data', '99')])))))
+        tx.deserialize(BytesIO(hex_str_to_bytes(self.nodes[2].createrawtransaction(inputs=[{'txid': txid, 'vout': 9}], outputs=multidict([(address, 99), (address2, 99), ('data', '99')])))))
         assert_equal(len(tx.vout), 3)
         assert_equal(
             bytes_to_hex_str(tx.serialize()),
-            self.nodes[2].createrawtransaction(inputs=[{'txid': txid, 'vout': 9}], outputs=[{address: 99}, {'data': '99'}, {'data': '99'}]),
+            self.nodes[2].createrawtransaction(inputs=[{'txid': txid, 'vout': 9}], outputs=[{address: 99}, {address2: 99}, {'data': '99'}]),
         )
 
         for type in ["bech32", "p2sh-segwit", "legacy"]: