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

fa4c8679ed94f215ce895938f7c3c169a2ce101e 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

1 files changed, 13 insertions, 3 deletions

diff --git a/src/rpc/rawtransaction.cpp b/src/rpc/rawtransaction.cpp
index f5f6c344ea..472b65f975 100644
--- a/src/rpc/rawtransaction.cpp
+++ b/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.",
                         {