Implement CWallet::SignTransaction using ScriptPubKeyMan::SignTransac…

…tion

Summary:
Backport of Core [[bitcoin/bitcoin#18115 | PR18115]] part [3/9] : bitcoin/bitcoin@f37de92

Depends on D8095

Test Plan:
  ninja all check-all

Reviewers: #bitcoin_abc, PiRK

Reviewed By: PiRK

Differential Revision: https://reviews.bitcoinabc.org/D8096

src/wallet/wallet.cpp

@@ -2707,39 +2707,79 @@ bool CWallet::SelectCoins(const std::vector<COutput> &vAvailableCoins,
     return res;
 }
 
-bool CWallet::SignTransaction(CMutableTransaction &tx) {
+bool CWallet::SignTransaction(CMutableTransaction &tx) const {
     AssertLockHeld(cs_wallet);
-    // sign the new tx
-    int nIn = 0;
-    for (CTxIn &input : tx.vin) {
+
+    // Build coins map
+    std::map<COutPoint, Coin> coins;
+    for (auto &input : tx.vin) {
         auto mi = mapWallet.find(input.prevout.GetTxId());
         if (mi == mapWallet.end() ||
             input.prevout.GetN() >= mi->second.tx->vout.size()) {
             return false;
         }
-        const CScript &scriptPubKey =
-            mi->second.tx->vout[input.prevout.GetN()].scriptPubKey;
-        const Amount amount = mi->second.tx->vout[input.prevout.GetN()].nValue;
-        SignatureData sigdata;
-        SigHashType sigHashType = SigHashType().withForkId();
+        const CWalletTx &wtx = mi->second;
+        coins[input.prevout] =
+            Coin(wtx.tx->vout[input.prevout.GetN()], wtx.m_confirm.block_height,
+                 wtx.IsCoinBase());
+    }
+    std::map<int, std::string> input_errors;
+    return SignTransaction(tx, coins, SigHashType().withForkId(), input_errors);
+}
+
+bool CWallet::SignTransaction(CMutableTransaction &tx,
+                              const std::map<COutPoint, Coin> &coins,
+                              SigHashType sighash,
+                              std::map<int, std::string> &input_errors) const {
+    // Sign the tx with ScriptPubKeyMans
+    // Because each ScriptPubKeyMan can sign more than one input, we need to
+    // keep track of each ScriptPubKeyMan that has signed this transaction. Each
+    // iteration, we may sign more txins than the txin that is specified in that
+    // iteration. We assume that each input is signed by only one
+    // ScriptPubKeyMan.
+    std::set<uint256> visited_spk_mans;
+    for (size_t i = 0; i < tx.vin.size(); i++) {
+        // Get the prevout
+        CTxIn &txin = tx.vin[i];
+        auto coin = coins.find(txin.prevout);
+        if (coin == coins.end() || coin->second.IsSpent()) {
+            input_errors[i] = "Input not found or already spent";
+            continue;
+        }
 
-        std::unique_ptr<SigningProvider> provider =
-            GetSigningProvider(scriptPubKey);
-        if (!provider) {
-            // We don't know about this scriptpbuKey;
-            return false;
+        // Check if this input is complete
+        SignatureData sigdata =
+            DataFromTransaction(tx, i, coin->second.GetTxOut());
+        if (sigdata.complete) {
+            continue;
         }
 
-        if (!ProduceSignature(*provider,
-                              MutableTransactionSignatureCreator(
-                                  &tx, nIn, amount, sigHashType),
-                              scriptPubKey, sigdata)) {
-            return false;
+        // Input needs to be signed, find the right ScriptPubKeyMan
+        std::set<ScriptPubKeyMan *> spk_mans =
+            GetScriptPubKeyMans(coin->second.GetTxOut().scriptPubKey, sigdata);
+        if (spk_mans.size() == 0) {
+            input_errors[i] = "Unable to sign input, missing keys";
+            continue;
+        }
+
+        for (auto &spk_man : spk_mans) {
+            // If we've already been signed by this spk_man, skip it
+            if (visited_spk_mans.count(spk_man->GetID()) > 0) {
+                continue;
+            }
+
+            // Sign the tx.
+            // spk_man->SignTransaction will return true if the transaction is
+            // complete, so we can exit early and return true if that happens.
+            if (spk_man->SignTransaction(tx, coins, sighash, input_errors)) {
+                return true;
+            }
+
+            // Add this spk_man to visited_spk_mans so we can skip it later
+            visited_spk_mans.insert(spk_man->GetID());
         }
-        UpdateInput(input, sigdata);
-        nIn++;
     }
-    return true;
+    return false;
 }
 
 bool CWallet::FundTransaction(CMutableTransaction &tx, Amount &nFeeRet,
@@ -4676,6 +4716,18 @@ ScriptPubKeyMan *CWallet::GetScriptPubKeyMan(const OutputType &type,
     return it->second;
 }
 
+std::set<ScriptPubKeyMan *>
+CWallet::GetScriptPubKeyMans(const CScript &script,
+                             SignatureData &sigdata) const {
+    std::set<ScriptPubKeyMan *> spk_mans;
+    for (const auto &spk_man_pair : m_spk_managers) {
+        if (spk_man_pair.second->CanProvide(script, sigdata)) {
+            spk_mans.insert(spk_man_pair.second.get());
+        }
+    }
+    return spk_mans;
+}
+
 ScriptPubKeyMan *CWallet::GetScriptPubKeyMan(const CScript &script) const {
     SignatureData sigdata;
     for (const auto &spk_man_pair : m_spk_managers) {

src/wallet/wallet.h

@@ -1097,8 +1097,14 @@ class CWallet final : public WalletStorage,
                          bool lockUnspents,
                          const std::set<int> &setSubtractFeeFromOutputs,
                          CCoinControl coinControl);
-    bool SignTransaction(CMutableTransaction &tx)
+    // Fetch the inputs and sign with SIGHASH_ALL.
+    bool SignTransaction(CMutableTransaction &tx) const
         EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
+    // Sign the tx given the input coins and sighash.
+    bool SignTransaction(CMutableTransaction &tx,
+                         const std::map<COutPoint, Coin> &coins,
+                         SigHashType sighash,
+                         std::map<int, std::string> &input_errors) const;
 
     /**
      * Create a new transaction paying the recipients with a set of coins
@@ -1427,6 +1433,11 @@ class CWallet final : public WalletStorage,
     //! Get the ScriptPubKeyMan by id
     ScriptPubKeyMan *GetScriptPubKeyMan(const uint256 &id) const;
 
+    //! Get all of the ScriptPubKeyMans for a script given additional
+    //! information in sigdata (populated by e.g. a psbt)
+    std::set<ScriptPubKeyMan *>
+    GetScriptPubKeyMans(const CScript &script, SignatureData &sigdata) const;
+
     //! Get the SigningProvider for a script
     std::unique_ptr<SigningProvider>
     GetSigningProvider(const CScript &script) const;