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

928af61cdb2c4de1c3d10e6fda13bbba5ca0bba9 allow send rpc take external inputs and solving data (Andrew Chow)
e39b5a5e7aa4d015257565ca79dc7b1f7a65e074 Tests for funding with external inputs (Andrew Chow)
38f5642cccf2b6708e58f5e2af5ecdcf752e61ec allow fundtx rpcs to work with external inputs (Andrew Chow)
d5cfb864ae16da62399bc97ab1ed54d32cf0cce9 Allow Coin Selection be able to take external inputs (Andrew Chow)
a00eb388e8046fe105666445dff6c91e8f8664cb 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 https://github.com/bitcoin/bitcoin/commit/928af61cdb2c4de1c3d10e6fda13bbba5ca0bba9
  meshcollider:
    Re-utACK 928af61cdb2c4de1c3d10e6fda13bbba5ca0bba9
  instagibbs:
    crACK 928af61cdb2c4de1c3d10e6fda13bbba5ca0bba9
  yanmaani:
    utACK 928af61.

Tree-SHA512: bc7a6ef8961a7f4971ea5985d75e2d6dc50c2a90b44c664a1c4b0f1be5c1c97823516358fdaab35771a4701dbefc0862127b1d0d4bfd02b4f20d2befa4434700

1 files changed, 12 insertions, 11 deletions

diff --git a/src/wallet/wallet.cpp b/src/wallet/wallet.cpp
index 1c18cdb1bc..bf6d8e7510 100644
--- a/src/wallet/wallet.cpp
+++ b/src/wallet/wallet.cpp
@@ -1448,19 +1448,13 @@ bool CWallet::AddWalletFlags(uint64_t flags)
 
 // Helper for producing a max-sized low-S low-R signature (eg 71 bytes)
 // or a max-sized low-S signature (e.g. 72 bytes) if use_max_sig is true
-bool CWallet::DummySignInput(CTxIn &tx_in, const CTxOut &txout, bool use_max_sig) const
+bool DummySignInput(const SigningProvider& provider, CTxIn &tx_in, const CTxOut &txout, bool use_max_sig)
 {
     // Fill in dummy signatures for fee calculation.
     const CScript& scriptPubKey = txout.scriptPubKey;
     SignatureData sigdata;
 
-    std::unique_ptr<SigningProvider> provider = GetSolvingProvider(scriptPubKey);
-    if (!provider) {
-        // We don't know about this scriptpbuKey;
-        return false;
-    }
-
-    if (!ProduceSignature(*provider, use_max_sig ? DUMMY_MAXIMUM_SIGNATURE_CREATOR : DUMMY_SIGNATURE_CREATOR, scriptPubKey, sigdata)) {
+    if (!ProduceSignature(provider, use_max_sig ? DUMMY_MAXIMUM_SIGNATURE_CREATOR : DUMMY_SIGNATURE_CREATOR, scriptPubKey, sigdata)) {
         return false;
     }
     UpdateInput(tx_in, sigdata);
@@ -1468,14 +1462,21 @@ bool CWallet::DummySignInput(CTxIn &tx_in, const CTxOut &txout, bool use_max_sig
 }
 
 // Helper for producing a bunch of max-sized low-S low-R signatures (eg 71 bytes)
-bool CWallet::DummySignTx(CMutableTransaction &txNew, const std::vector<CTxOut> &txouts, bool use_max_sig) const
+bool CWallet::DummySignTx(CMutableTransaction &txNew, const std::vector<CTxOut> &txouts, const CCoinControl* coin_control) const
 {
     // Fill in dummy signatures for fee calculation.
     int nIn = 0;
     for (const auto& txout : txouts)
     {
-        if (!DummySignInput(txNew.vin[nIn], txout, use_max_sig)) {
-            return false;
+        CTxIn& txin = txNew.vin[nIn];
+        // Use max sig if watch only inputs were used or if this particular input is an external input
+        // to ensure a sufficient fee is attained for the requested feerate.
+        const bool use_max_sig = coin_control && (coin_control->fAllowWatchOnly || coin_control->IsExternalSelected(txin.prevout));
+        const std::unique_ptr<SigningProvider> provider = GetSolvingProvider(txout.scriptPubKey);
+        if (!provider || !DummySignInput(*provider, txin, txout, use_max_sig)) {
+            if (!coin_control || !DummySignInput(coin_control->m_external_provider, txin, txout, use_max_sig)) {
+                return false;
+            }
         }
 
         nIn++;