From bde7c9fa38775a81d53ac0484fa9c98076a0c7d1 Mon Sep 17 00:00:00 2001
From: Andrew Chow <achow101-github@achow101.com>
Date: Tue, 11 Feb 2020 17:10:25 -0500
Subject: Implement SignTransaction in DescriptorScriptPubKeyMan

---
 src/wallet/scriptpubkeyman.cpp | 11 ++++++++++-
 src/wallet/wallet.cpp          | 41 ++++++++++++-----------------------------
 2 files changed, 22 insertions(+), 30 deletions(-)

diff --git a/src/wallet/scriptpubkeyman.cpp b/src/wallet/scriptpubkeyman.cpp
index 67063ad23c..1eb9dc4d7a 100644
--- a/src/wallet/scriptpubkeyman.cpp
+++ b/src/wallet/scriptpubkeyman.cpp
@@ -1943,7 +1943,16 @@ bool DescriptorScriptPubKeyMan::CanProvide(const CScript& script, SignatureData&
 
 bool DescriptorScriptPubKeyMan::SignTransaction(CMutableTransaction& tx, const std::map<COutPoint, Coin>& coins, int sighash, std::map<int, std::string>& input_errors) const
 {
-    return false;
+    std::unique_ptr<FlatSigningProvider> keys = MakeUnique<FlatSigningProvider>();
+    for (const auto& coin_pair : coins) {
+        std::unique_ptr<FlatSigningProvider> coin_keys = GetSigningProvider(coin_pair.second.out.scriptPubKey, true);
+        if (!coin_keys) {
+            continue;
+        }
+        *keys = Merge(*keys, *coin_keys);
+    }
+
+    return ::SignTransaction(tx, keys.get(), coins, sighash, input_errors);
 }
 
 SigningResult DescriptorScriptPubKeyMan::SignMessage(const std::string& message, const PKHash& pkhash, std::string& str_sig) const
diff --git a/src/wallet/wallet.cpp b/src/wallet/wallet.cpp
index 8f42d1d75f..062162bdf7 100644
--- a/src/wallet/wallet.cpp
+++ b/src/wallet/wallet.cpp
@@ -2428,11 +2428,17 @@ bool CWallet::SignTransaction(CMutableTransaction& tx) const
 
 bool CWallet::SignTransaction(CMutableTransaction& tx, const std::map<COutPoint, Coin>& coins, int 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;
+    // Try to sign with all ScriptPubKeyMans
+    for (ScriptPubKeyMan* spk_man : GetAllScriptPubKeyMans()) {
+        // 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;
+        }
+    }
+
+    // At this point, one input was not fully signed otherwise we would have exited already
+    // Find that input and figure out what went wrong.
     for (unsigned int i = 0; i < tx.vin.size(); i++) {
         // Get the prevout
         CTxIn& txin = tx.vin[i];
@@ -2444,33 +2450,10 @@ bool CWallet::SignTransaction(CMutableTransaction& tx, const std::map<COutPoint,
 
         // Check if this input is complete
         SignatureData sigdata = DataFromTransaction(tx, i, coin->second.out);
-        if (sigdata.complete) {
-            continue;
-        }
-
-        // Input needs to be signed, find the right ScriptPubKeyMan
-        std::set<ScriptPubKeyMan*> spk_mans = GetScriptPubKeyMans(coin->second.out.scriptPubKey, sigdata);
-        if (spk_mans.size() == 0) {
+        if (!sigdata.complete) {
             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());
-        }
     }
     return false;
 }
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