output_script.cpp

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// Copyright (c) 2010 Satoshi Nakamoto
// Copyright (c) 2009-present The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.

#include <key_io.h>
#include <outputtype.h>
#include <pubkey.h>
#include <rpc/protocol.h>
#include <rpc/request.h>
#include <rpc/server.h>
#include <rpc/util.h>
#include <script/descriptor.h>
#include <script/script.h>
#include <script/signingprovider.h>
#include <tinyformat.h>
#include <univalue.h>
#include <util/check.h>
#include <util/strencodings.h>

#include <cstdint>
#include <memory>
#include <optional>
#include <string>
#include <string_view>
#include <tuple>
#include <vector>

static RPCHelpMan validateaddress()
{
    return RPCHelpMan{
        "validateaddress",
        "Return information about the given bitcoin address.\n",
        {
            {"address", RPCArg::Type::STR, RPCArg::Optional::NO, "The bitcoin address to validate"},
        },
        RPCResult{
            RPCResult::Type::OBJ, "", "",
            {
                {RPCResult::Type::BOOL, "isvalid", "If the address is valid or not"},
                {RPCResult::Type::STR, "address", /*optional=*/true, "The bitcoin address validated"},
                {RPCResult::Type::STR_HEX, "scriptPubKey", /*optional=*/true, "The hex-encoded output script generated by the address"},
                {RPCResult::Type::BOOL, "isscript", /*optional=*/true, "If the key is a script"},
                {RPCResult::Type::BOOL, "iswitness", /*optional=*/true, "If the address is a witness address"},
                {RPCResult::Type::NUM, "witness_version", /*optional=*/true, "The version number of the witness program"},
                {RPCResult::Type::STR_HEX, "witness_program", /*optional=*/true, "The hex value of the witness program"},
                {RPCResult::Type::STR, "error", /*optional=*/true, "Error message, if any"},
                {RPCResult::Type::ARR, "error_locations", /*optional=*/true, "Indices of likely error locations in address, if known (e.g. Bech32 errors)",
                    {
                        {RPCResult::Type::NUM, "index", "index of a potential error"},
                    }},
            }
        },
        RPCExamples{
            HelpExampleCli("validateaddress", "\"" + EXAMPLE_ADDRESS[0] + "\"") +
            HelpExampleRpc("validateaddress", "\"" + EXAMPLE_ADDRESS[0] + "\"")
        },
        [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
        {
            std::string error_msg;
            std::vector<int> error_locations;
            CTxDestination dest = DecodeDestination(request.params[0].get_str(), error_msg, &error_locations);
            const bool isValid = IsValidDestination(dest);
            CHECK_NONFATAL(isValid == error_msg.empty());

            UniValue ret(UniValue::VOBJ);
            ret.pushKV("isvalid", isValid);
            if (isValid) {
                std::string currentAddress = EncodeDestination(dest);
                ret.pushKV("address", currentAddress);

                CScript scriptPubKey = GetScriptForDestination(dest);
                ret.pushKV("scriptPubKey", HexStr(scriptPubKey));

                UniValue detail = DescribeAddress(dest);
                ret.pushKVs(std::move(detail));
            } else {
                UniValue error_indices(UniValue::VARR);
                for (int i : error_locations) error_indices.push_back(i);
                ret.pushKV("error_locations", std::move(error_indices));
                ret.pushKV("error", error_msg);
            }

            return ret;
        },
    };
}

static RPCHelpMan createmultisig()
{
    return RPCHelpMan{
        "createmultisig",
        "Creates a multi-signature address with n signatures of m keys required.\n"
        "It returns a json object with the address and redeemScript.\n",
        {
            {"nrequired", RPCArg::Type::NUM, RPCArg::Optional::NO, "The number of required signatures out of the m keys."},
            {"keys", RPCArg::Type::ARR, RPCArg::Optional::NO, "The hex-encoded public keys.",
                {
                    {"key", RPCArg::Type::STR_HEX, RPCArg::Optional::OMITTED, "The hex-encoded public key"},
                }},
            {"address_type", RPCArg::Type::STR, RPCArg::Default{"legacy"}, "The address type to use. Options are \"legacy\", \"p2sh-segwit\", and \"bech32\"."},
        },
        RPCResult{
            RPCResult::Type::OBJ, "", "",
            {
                {RPCResult::Type::STR, "address", "The value of the new multisig address."},
                {RPCResult::Type::STR_HEX, "redeemScript", "The string value of the hex-encoded redemption script."},
                {RPCResult::Type::STR, "descriptor", "The descriptor for this multisig"},
                {RPCResult::Type::ARR, "warnings", /*optional=*/true, "Any warnings resulting from the creation of this multisig",
                {
                    {RPCResult::Type::STR, "", ""},
                }},
            }
        },
        RPCExamples{
            "\nCreate a multisig address from 2 public keys\n"
            + HelpExampleCli("createmultisig", "2 \"[\\\"03789ed0bb717d88f7d321a368d905e7430207ebbd82bd342cf11ae157a7ace5fd\\\",\\\"03dbc6764b8884a92e871274b87583e6d5c2a58819473e17e107ef3f6aa5a61626\\\"]\"") +
            "\nAs a JSON-RPC call\n"
            + HelpExampleRpc("createmultisig", "2, [\"03789ed0bb717d88f7d321a368d905e7430207ebbd82bd342cf11ae157a7ace5fd\",\"03dbc6764b8884a92e871274b87583e6d5c2a58819473e17e107ef3f6aa5a61626\"]")
                },
        [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
        {
            int required = request.params[0].getInt<int>();

            // Get the public keys
            const UniValue& keys = request.params[1].get_array();
            std::vector<CPubKey> pubkeys;
            pubkeys.reserve(keys.size());
            for (unsigned int i = 0; i < keys.size(); ++i) {
                pubkeys.push_back(HexToPubKey(keys[i].get_str()));
            }

            // Get the output type
            auto address_type{self.Arg<std::string_view>("address_type")};
            auto output_type{ParseOutputType(address_type)};
            if (!output_type) {
                throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, tfm::format("Unknown address type '%s'", address_type));
            } else if (output_type.value() == OutputType::BECH32M) {
                throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "createmultisig cannot create bech32m multisig addresses");
            }

            FlatSigningProvider keystore;
            CScript inner;
            const CTxDestination dest = AddAndGetMultisigDestination(required, pubkeys, output_type.value(), keystore, inner);

            // Make the descriptor
            std::unique_ptr<Descriptor> descriptor = InferDescriptor(GetScriptForDestination(dest), keystore);

            UniValue result(UniValue::VOBJ);
            result.pushKV("address", EncodeDestination(dest));
            result.pushKV("redeemScript", HexStr(inner));
            result.pushKV("descriptor", descriptor->ToString());

            UniValue warnings(UniValue::VARR);
            if (descriptor->GetOutputType() != output_type.value()) {
                // Only warns if the user has explicitly chosen an address type we cannot generate
                warnings.push_back("Unable to make chosen address type, please ensure no uncompressed public keys are present.");
            }
            PushWarnings(warnings, result);

            return result;
        },
    };
}

static RPCHelpMan getdescriptorinfo()
{
    const std::string EXAMPLE_DESCRIPTOR = "wpkh([d34db33f/84h/0h/0h]0279be667ef9dcbbac55a06295Ce870b07029Bfcdb2dce28d959f2815b16f81798)";

    return RPCHelpMan{
        "getdescriptorinfo",
        "Analyses a descriptor.\n",
        {
            {"descriptor", RPCArg::Type::STR, RPCArg::Optional::NO, "The descriptor."},
        },
        RPCResult{
            RPCResult::Type::OBJ, "", "",
            {
                {RPCResult::Type::STR, "descriptor", "The descriptor in canonical form, without private keys. For a multipath descriptor, only the first will be returned."},
                {RPCResult::Type::ARR, "multipath_expansion", /*optional=*/true, "All descriptors produced by expanding multipath derivation elements. Only if the provided descriptor specifies multipath derivation elements.",
                {
                    {RPCResult::Type::STR, "", ""},
                }},
                {RPCResult::Type::STR, "checksum", "The checksum for the input descriptor"},
                {RPCResult::Type::BOOL, "isrange", "Whether the descriptor is ranged"},
                {RPCResult::Type::BOOL, "issolvable", "Whether the descriptor is solvable"},
                {RPCResult::Type::BOOL, "hasprivatekeys", "Whether the input descriptor contained at least one private key"},
            }
        },
        RPCExamples{
            "Analyse a descriptor\n" +
            HelpExampleCli("getdescriptorinfo", "\"" + EXAMPLE_DESCRIPTOR + "\"") +
            HelpExampleRpc("getdescriptorinfo", "\"" + EXAMPLE_DESCRIPTOR + "\"")
        },
        [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
        {
            FlatSigningProvider provider;
            std::string error;
            auto descs = Parse(self.Arg<std::string_view>("descriptor"), provider, error);
            if (descs.empty()) {
                throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, error);
            }

            UniValue result(UniValue::VOBJ);
            result.pushKV("descriptor", descs.at(0)->ToString());

            if (descs.size() > 1) {
                UniValue multipath_descs(UniValue::VARR);
                for (const auto& d : descs) {
                    multipath_descs.push_back(d->ToString());
                }
                result.pushKV("multipath_expansion", multipath_descs);
            }

            result.pushKV("checksum", GetDescriptorChecksum(request.params[0].get_str()));
            result.pushKV("isrange", descs.at(0)->IsRange());
            result.pushKV("issolvable", descs.at(0)->IsSolvable());
            result.pushKV("hasprivatekeys", provider.keys.size() > 0);
            return result;
        },
    };
}

static UniValue DeriveAddresses(const Descriptor* desc, int64_t range_begin, int64_t range_end, FlatSigningProvider& key_provider)
{
    UniValue addresses(UniValue::VARR);

    for (int64_t i = range_begin; i <= range_end; ++i) {
        FlatSigningProvider provider;
        std::vector<CScript> scripts;
        if (!desc->Expand(i, key_provider, scripts, provider)) {
            throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Cannot derive script without private keys");
        }

        for (const CScript& script : scripts) {
            CTxDestination dest;
            if (!ExtractDestination(script, dest)) {
                // ExtractDestination no longer returns true for P2PK since it doesn't have a corresponding address
                // However combo will output P2PK and should just ignore that script
                if (scripts.size() > 1 && std::get_if<PubKeyDestination>(&dest)) {
                    continue;
                }
                throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Descriptor does not have a corresponding address");
            }

            addresses.push_back(EncodeDestination(dest));
        }
    }

    // This should not be possible, but an assert seems overkill:
    if (addresses.empty()) {
        throw JSONRPCError(RPC_MISC_ERROR, "Unexpected empty result");
    }

    return addresses;
}

static RPCHelpMan deriveaddresses()
{
    const std::string EXAMPLE_DESCRIPTOR = "wpkh([d34db33f/84h/0h/0h]xpub6DJ2dNUysrn5Vt36jH2KLBT2i1auw1tTSSomg8PhqNiUtx8QX2SvC9nrHu81fT41fvDUnhMjEzQgXnQjKEu3oaqMSzhSrHMxyyoEAmUHQbY/0/*)#cjjspncu";

    return RPCHelpMan{
        "deriveaddresses",
        "Derives one or more addresses corresponding to an output descriptor.\n"
         "Examples of output descriptors are:\n"
         "    pkh(<pubkey>)                                     P2PKH outputs for the given pubkey\n"
         "    wpkh(<pubkey>)                                    Native segwit P2PKH outputs for the given pubkey\n"
         "    sh(multi(<n>,<pubkey>,<pubkey>,...))              P2SH-multisig outputs for the given threshold and pubkeys\n"
         "    raw(<hex script>)                                 Outputs whose output script equals the specified hex-encoded bytes\n"
         "    tr(<pubkey>,multi_a(<n>,<pubkey>,<pubkey>,...))   P2TR-multisig outputs for the given threshold and pubkeys\n"
         "\nIn the above, <pubkey> either refers to a fixed public key in hexadecimal notation, or to an xpub/xprv optionally followed by one\n"
         "or more path elements separated by \"/\", where \"h\" represents a hardened child key.\n"
        "For more information on output descriptors, see the documentation in the doc/descriptors.md file.\n",
        {
            {"descriptor", RPCArg::Type::STR, RPCArg::Optional::NO, "The descriptor."},
            {"range", RPCArg::Type::RANGE, RPCArg::Optional::OMITTED, "If a ranged descriptor is used, this specifies the end or the range (in [begin,end] notation) to derive."},
        },
        {
            RPCResult{"for single derivation descriptors",
                RPCResult::Type::ARR, "", "",
                {
                    {RPCResult::Type::STR, "address", "the derived addresses"},
                }
            },
            RPCResult{"for multipath descriptors",
                RPCResult::Type::ARR, "", "The derived addresses for each of the multipath expansions of the descriptor, in multipath specifier order",
                {
                    {
                        RPCResult::Type::ARR, "", "The derived addresses for a multipath descriptor expansion",
                        {
                            {RPCResult::Type::STR, "address", "the derived address"},
                        },
                    },
                },
            },
        },
        RPCExamples{
            "First three native segwit receive addresses\n" +
            HelpExampleCli("deriveaddresses", "\"" + EXAMPLE_DESCRIPTOR + "\" \"[0,2]\"") +
            HelpExampleRpc("deriveaddresses", "\"" + EXAMPLE_DESCRIPTOR + "\", \"[0,2]\"")
        },
        [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
        {
            auto desc_str{self.Arg<std::string_view>("descriptor")};

            int64_t range_begin = 0;
            int64_t range_end = 0;

            if (request.params.size() >= 2 && !request.params[1].isNull()) {
                std::tie(range_begin, range_end) = ParseDescriptorRange(request.params[1]);
            }

            FlatSigningProvider key_provider;
            std::string error;
            auto descs = Parse(desc_str, key_provider, error, /* require_checksum = */ true);
            if (descs.empty()) {
                throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, error);
            }
            auto& desc = descs.at(0);
            if (!desc->IsRange() && request.params.size() > 1) {
                throw JSONRPCError(RPC_INVALID_PARAMETER, "Range should not be specified for an un-ranged descriptor");
            }

            if (desc->IsRange() && request.params.size() == 1) {
                throw JSONRPCError(RPC_INVALID_PARAMETER, "Range must be specified for a ranged descriptor");
            }

            UniValue addresses = DeriveAddresses(desc.get(), range_begin, range_end, key_provider);

            if (descs.size() == 1) {
                return addresses;
            }

            UniValue ret(UniValue::VARR);
            ret.push_back(addresses);
            for (size_t i = 1; i < descs.size(); ++i) {
                ret.push_back(DeriveAddresses(descs.at(i).get(), range_begin, range_end, key_provider));
            }
            return ret;
        },
    };
}

void RegisterOutputScriptRPCCommands(CRPCTable& t)
{
    static const CRPCCommand commands[]{
        {"util", &validateaddress},
        {"util", &createmultisig},
        {"util", &deriveaddresses},
        {"util", &getdescriptorinfo},
    };
    for (const auto& c : commands) {
        t.appendCommand(c.name, &c);
    }
}