Merge bitcoin/bitcoin#17211: Allow fundrawtransaction and walletcreatefundedpsbt to take external inputs

928af61 allow send rpc take external inputs and solving data (Andrew Chow)
e39b5a5 Tests for funding with external inputs (Andrew Chow)
38f5642 allow fundtx rpcs to work with external inputs (Andrew Chow)
d5cfb86 Allow Coin Selection be able to take external inputs (Andrew Chow)
a00eb38 Allow CInputCoin to also be constructed with COutPoint and CTxOut (Andrew Chow)

Pull request description:

  Currently `fundrawtransaction` and `walletcreatefundedpsbt` both do not allow external inputs as the wallet does not have the information necessary to estimate their fees.

  This PR adds an additional argument to both those RPCs which allows the user to specify solving data. This way, the wallet can use that solving data to estimate the size of those inputs. The solving data can be public keys, scripts, or descriptors.

ACKs for top commit:
  prayank23:
    reACK bitcoin/bitcoin@928af61
  meshcollider:
    Re-utACK 928af61
  instagibbs:
    crACK 928af61
  yanmaani:
    utACK 928af61.

Tree-SHA512: bc7a6ef8961a7f4971ea5985d75e2d6dc50c2a90b44c664a1c4b0f1be5c1c97823516358fdaab35771a4701dbefc0862127b1d0d4bfd02b4f20d2befa4434700

Author: meshcollider

src/wallet/coincontrol.h

@@ -9,9 +9,14 @@
 #include <policy/feerate.h>
 #include <policy/fees.h>
 #include <primitives/transaction.h>
+#include <script/keyorigin.h>
+#include <script/signingprovider.h>
 #include <script/standard.h>
 
 #include <optional>
+#include <algorithm>
+#include <map>
+#include <set>
 
 const int DEFAULT_MIN_DEPTH = 0;
 const int DEFAULT_MAX_DEPTH = 9999999;
@@ -53,6 +58,8 @@ class CCoinControl
     int m_min_depth = DEFAULT_MIN_DEPTH;
     //! Maximum chain depth value for coin availability
     int m_max_depth = DEFAULT_MAX_DEPTH;
+    //! SigningProvider that has pubkeys and scripts to do spend size estimation for external inputs
+    FlatSigningProvider m_external_provider;
 
     CCoinControl();
 
@@ -66,11 +73,32 @@ class CCoinControl
         return (setSelected.count(output) > 0);
     }
 
+    bool IsExternalSelected(const COutPoint& output) const
+    {
+        return (m_external_txouts.count(output) > 0);
+    }
+
+    bool GetExternalOutput(const COutPoint& outpoint, CTxOut& txout) const
+    {
+        const auto ext_it = m_external_txouts.find(outpoint);
+        if (ext_it == m_external_txouts.end()) {
+            return false;
+        }
+        txout = ext_it->second;
+        return true;
+    }
+
     void Select(const COutPoint& output)
     {
         setSelected.insert(output);
     }
 
+    void Select(const COutPoint& outpoint, const CTxOut& txout)
+    {
+        setSelected.insert(outpoint);
+        m_external_txouts.emplace(outpoint, txout);
+    }
+
     void UnSelect(const COutPoint& output)
     {
         setSelected.erase(output);
@@ -88,6 +116,7 @@ class CCoinControl
 
 private:
     std::set<COutPoint> setSelected;
+    std::map<COutPoint, CTxOut> m_external_txouts;
 };
 
 #endif // BITCOIN_WALLET_COINCONTROL_H

src/wallet/coinselection.h

@@ -37,6 +37,18 @@ class CInputCoin {
         m_input_bytes = input_bytes;
     }
 
+    CInputCoin(const COutPoint& outpoint_in, const CTxOut& txout_in)
+    {
+        outpoint = outpoint_in;
+        txout = txout_in;
+        effective_value = txout.nValue;
+    }
+
+    CInputCoin(const COutPoint& outpoint_in, const CTxOut& txout_in, int input_bytes) : CInputCoin(outpoint_in, txout_in)
+    {
+        m_input_bytes = input_bytes;
+    }
+
     COutPoint outpoint;
     CTxOut txout;
     CAmount effective_value;

src/wallet/rpcwallet.cpp

@@ -43,6 +43,7 @@
 
 #include <univalue.h>
 
+#include <map>
 
 using interfaces::FoundBlock;
 
@@ -3213,6 +3214,7 @@ void FundTransaction(CWallet& wallet, CMutableTransaction& tx, CAmount& fee_out,
                 {"fee_rate", UniValueType()}, // will be checked by AmountFromValue() in SetFeeEstimateMode()
                 {"feeRate", UniValueType()}, // will be checked by AmountFromValue() below
                 {"psbt", UniValueType(UniValue::VBOOL)},
+                {"solving_data", UniValueType(UniValue::VOBJ)},
                 {"subtractFeeFromOutputs", UniValueType(UniValue::VARR)},
                 {"subtract_fee_from_outputs", UniValueType(UniValue::VARR)},
                 {"replaceable", UniValueType(UniValue::VBOOL)},
@@ -3289,6 +3291,54 @@ void FundTransaction(CWallet& wallet, CMutableTransaction& tx, CAmount& fee_out,
         coinControl.fAllowWatchOnly = ParseIncludeWatchonly(NullUniValue, wallet);
     }
 
+    if (options.exists("solving_data")) {
+        UniValue solving_data = options["solving_data"].get_obj();
+        if (solving_data.exists("pubkeys")) {
+            for (const UniValue& pk_univ : solving_data["pubkeys"].get_array().getValues()) {
+                const std::string& pk_str = pk_univ.get_str();
+                if (!IsHex(pk_str)) {
+                    throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, strprintf("'%s' is not hex", pk_str));
+                }
+                const std::vector<unsigned char> data(ParseHex(pk_str));
+                CPubKey pubkey(data.begin(), data.end());
+                if (!pubkey.IsFullyValid()) {
+                    throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, strprintf("'%s' is not a valid public key", pk_str));
+                }
+                coinControl.m_external_provider.pubkeys.emplace(pubkey.GetID(), pubkey);
+                // Add witness script for pubkeys
+                const CScript wit_script = GetScriptForDestination(WitnessV0KeyHash(pubkey));
+                coinControl.m_external_provider.scripts.emplace(CScriptID(wit_script), wit_script);
+            }
+        }
+
+        if (solving_data.exists("scripts")) {
+            for (const UniValue& script_univ : solving_data["scripts"].get_array().getValues()) {
+                const std::string& script_str = script_univ.get_str();
+                if (!IsHex(script_str)) {
+                    throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, strprintf("'%s' is not hex", script_str));
+                }
+                std::vector<unsigned char> script_data(ParseHex(script_str));
+                const CScript script(script_data.begin(), script_data.end());
+                coinControl.m_external_provider.scripts.emplace(CScriptID(script), script);
+            }
+        }
+
+        if (solving_data.exists("descriptors")) {
+            for (const UniValue& desc_univ : solving_data["descriptors"].get_array().getValues()) {
+                const std::string& desc_str  = desc_univ.get_str();
+                FlatSigningProvider desc_out;
+                std::string error;
+                std::vector<CScript> scripts_temp;
+                std::unique_ptr<Descriptor> desc = Parse(desc_str, desc_out, error, true);
+                if (!desc) {
+                    throw JSONRPCError(RPC_INVALID_PARAMETER, strprintf("Unable to parse descriptor '%s': %s", desc_str, error));
+                }
+                desc->Expand(0, desc_out, scripts_temp, desc_out);
+                coinControl.m_external_provider = Merge(coinControl.m_external_provider, desc_out);
+            }
+        }
+    }
+
     if (tx.vout.size() == 0)
         throw JSONRPCError(RPC_INVALID_PARAMETER, "TX must have at least one output");
 
@@ -3306,6 +3356,19 @@ void FundTransaction(CWallet& wallet, CMutableTransaction& tx, CAmount& fee_out,
         setSubtractFeeFromOutputs.insert(pos);
     }
 
+    // Fetch specified UTXOs from the UTXO set to get the scriptPubKeys and values of the outputs being selected
+    // and to match with the given solving_data. Only used for non-wallet outputs.
+    std::map<COutPoint, Coin> coins;
+    for (const CTxIn& txin : tx.vin) {
+        coins[txin.prevout]; // Create empty map entry keyed by prevout.
+    }
+    wallet.chain().findCoins(coins);
+    for (const auto& coin : coins) {
+        if (!coin.second.out.IsNull()) {
+            coinControl.Select(coin.first, coin.second.out);
+        }
+    }
+
     bilingual_str error;
 
     if (!FundTransaction(wallet, tx, fee_out, change_position, error, lockUnspents, setSubtractFeeFromOutputs, coinControl)) {
@@ -3321,8 +3384,9 @@ static RPCHelpMan fundrawtransaction()
                 "No existing outputs will be modified unless \"subtractFeeFromOutputs\" is specified.\n"
                 "Note that inputs which were signed may need to be resigned after completion since in/outputs have been added.\n"
                 "The inputs added will not be signed, use signrawtransactionwithkey\n"
-                " or signrawtransactionwithwallet for that.\n"
-                "Note that all existing inputs must have their previous output transaction be in the wallet.\n"
+                "or signrawtransactionwithwallet for that.\n"
+                "All existing inputs must either have their previous output transaction be in the wallet\n"
+                "or be in the UTXO set. Solving data must be provided for non-wallet inputs.\n"
                 "Note that all inputs selected must be of standard form and P2SH scripts must be\n"
                 "in the wallet using importaddress or addmultisigaddress (to calculate fees).\n"
                 "You can see whether this is the case by checking the \"solvable\" field in the listunspent output.\n"
@@ -3357,6 +3421,26 @@ static RPCHelpMan fundrawtransaction()
                             {"conf_target", RPCArg::Type::NUM, RPCArg::DefaultHint{"wallet -txconfirmtarget"}, "Confirmation target in blocks"},
                             {"estimate_mode", RPCArg::Type::STR, RPCArg::Default{"unset"}, std::string() + "The fee estimate mode, must be one of (case insensitive):\n"
                             "       \"" + FeeModes("\"\n\"") + "\""},
+                            {"solving_data", RPCArg::Type::OBJ, RPCArg::Optional::OMITTED_NAMED_ARG, "Keys and scripts needed for producing a final transaction with a dummy signature.\n"
+                                "Used for fee estimation during coin selection.",
+                                {
+                                    {"pubkeys", RPCArg::Type::ARR, RPCArg::Default{UniValue::VARR}, "Public keys involved in this transaction.",
+                                        {
+                                            {"pubkey", RPCArg::Type::STR_HEX, RPCArg::Optional::OMITTED, "A public key"},
+                                        },
+                                    },
+                                    {"scripts", RPCArg::Type::ARR, RPCArg::Default{UniValue::VARR}, "Scripts involved in this transaction.",
+                                        {
+                                            {"script", RPCArg::Type::STR_HEX, RPCArg::Optional::OMITTED, "A script"},
+                                        },
+                                    },
+                                    {"descriptors", RPCArg::Type::ARR, RPCArg::Default{UniValue::VARR}, "Descriptors that provide solving data for this transaction.",
+                                        {
+                                            {"descriptor", RPCArg::Type::STR, RPCArg::Optional::OMITTED, "A descriptor"},
+                                        },
+                                    }
+                                }
+                            },
                         },
                         "options"},
                     {"iswitness", RPCArg::Type::BOOL, RPCArg::DefaultHint{"depends on heuristic tests"}, "Whether the transaction hex is a serialized witness transaction.\n"
@@ -4202,6 +4286,26 @@ static RPCHelpMan send()
                     },
                     {"replaceable", RPCArg::Type::BOOL, RPCArg::DefaultHint{"wallet default"}, "Marks this transaction as BIP125 replaceable.\n"
                                                   "Allows this transaction to be replaced by a transaction with higher fees"},
+                    {"solving_data", RPCArg::Type::OBJ, RPCArg::Optional::OMITTED_NAMED_ARG, "Keys and scripts needed for producing a final transaction with a dummy signature.\n"
+                        "Used for fee estimation during coin selection.",
+                        {
+                            {"pubkeys", RPCArg::Type::ARR, RPCArg::Default{UniValue::VARR}, "Public keys involved in this transaction.",
+                                {
+                                    {"pubkey", RPCArg::Type::STR_HEX, RPCArg::Optional::OMITTED, "A public key"},
+                                },
+                            },
+                            {"scripts", RPCArg::Type::ARR, RPCArg::Default{UniValue::VARR}, "Scripts involved in this transaction.",
+                                {
+                                    {"script", RPCArg::Type::STR_HEX, RPCArg::Optional::OMITTED, "A script"},
+                                },
+                            },
+                            {"descriptors", RPCArg::Type::ARR, RPCArg::Default{UniValue::VARR}, "Descriptors that provide solving data for this transaction.",
+                                {
+                                    {"descriptor", RPCArg::Type::STR, RPCArg::Optional::OMITTED, "A descriptor"},
+                                },
+                            }
+                        }
+                    },
                 },
                 "options"},
         },
@@ -4489,7 +4593,9 @@ static RPCHelpMan walletcreatefundedpsbt()
 {
     return RPCHelpMan{"walletcreatefundedpsbt",
                 "\nCreates and funds a transaction in the Partially Signed Transaction format.\n"
-                "Implements the Creator and Updater roles.\n",
+                "Implements the Creator and Updater roles.\n"
+                "All existing inputs must either have their previous output transaction be in the wallet\n"
+                "or be in the UTXO set. Solving data must be provided for non-wallet inputs.\n",
                 {
                     {"inputs", RPCArg::Type::ARR, RPCArg::Optional::OMITTED_NAMED_ARG, "Leave empty to add inputs automatically. See add_inputs option.",
                         {
@@ -4546,6 +4652,26 @@ static RPCHelpMan walletcreatefundedpsbt()
                             {"conf_target", RPCArg::Type::NUM, RPCArg::DefaultHint{"wallet -txconfirmtarget"}, "Confirmation target in blocks"},
                             {"estimate_mode", RPCArg::Type::STR, RPCArg::Default{"unset"}, std::string() + "The fee estimate mode, must be one of (case insensitive):\n"
                             "         \"" + FeeModes("\"\n\"") + "\""},
+                            {"solving_data", RPCArg::Type::OBJ, RPCArg::Optional::OMITTED_NAMED_ARG, "Keys and scripts needed for producing a final transaction with a dummy signature.\n"
+                                "Used for fee estimation during coin selection.",
+                                {
+                                    {"pubkeys", RPCArg::Type::ARR, RPCArg::Default{UniValue::VARR}, "Public keys involved in this transaction.",
+                                        {
+                                            {"pubkey", RPCArg::Type::STR_HEX, RPCArg::Optional::OMITTED, "A public key"},
+                                        },
+                                    },
+                                    {"scripts", RPCArg::Type::ARR, RPCArg::Default{UniValue::VARR}, "Scripts involved in this transaction.",
+                                        {
+                                            {"script", RPCArg::Type::STR_HEX, RPCArg::Optional::OMITTED, "A script"},
+                                        },
+                                    },
+                                    {"descriptors", RPCArg::Type::ARR, RPCArg::Default{UniValue::VARR}, "Descriptors that provide solving data for this transaction.",
+                                        {
+                                            {"descriptor", RPCArg::Type::STR, RPCArg::Optional::OMITTED, "A descriptor"},
+                                        },
+                                    }
+                                }
+                            },
                         },
                         "options"},
                     {"bip32derivs", RPCArg::Type::BOOL, RPCArg::Default{true}, "Include BIP 32 derivation paths for public keys if we know them"},