Motivation
Each key may only appear once, i.e. there can only be one 'data' output, and no address may be duplicated.
https://bitcoincore.org/en/doc/29.0.0/rpc/rawtransactions/createrawtransaction/
If and when #32406 gets merged, it will be helpful to use multiple data outputs while creating a transaction.
Related comment: #32406 (comment)
Possible solution
Remove the check for duplicate data key.
Relevant function:
std::vector<std::pair<CTxDestination, CAmount>> ParseOutputs(const UniValue& outputs)
{
// Duplicate checking
std::set<CTxDestination> destinations;
std::vector<std::pair<CTxDestination, CAmount>> parsed_outputs;
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");
CTxDestination destination{CNoDestination{CScript() << OP_RETURN << data}};
CAmount amount{0};
parsed_outputs.emplace_back(destination, amount);
} else {
CTxDestination destination{DecodeDestination(name_)};
CAmount amount{AmountFromValue(outputs[name_])};
if (!IsValidDestination(destination)) {
throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, std::string("Invalid Bitcoin address: ") + name_);
}
if (!destinations.insert(destination).second) {
throw JSONRPCError(RPC_INVALID_PARAMETER, std::string("Invalid parameter, duplicated address: ") + name_);
}
parsed_outputs.emplace_back(destination, amount);
}
}
return parsed_outputs;
}
Useful Skills
- Compiling Bitcoin Core from source
- Running the C++ unit tests and the Python functional tests
Guidance for new contributors
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