psbt: Change m_tap_tree to store just the tuples

achow101 · achow101 · commit 0577d423adda · 2022-10-06T15:32:51.000-04:00
Instead of having an entire TaprootBuilder which may or may not be
complete, and could potentially have future changes that interact oddly
with taproot tree tuples, have m_tap_tree be just the tuples.

When needed in other a TaprootBuilder for actual use, the tuples will be
added to a a TaprootBuilder that, in the future, can take in whatever
other data is needed as well.
diff --git a/src/psbt.cpp b/src/psbt.cpp
@@ -218,8 +218,14 @@ void PSBTOutput::FillSignatureData(SignatureData& sigdata) const
     for (const auto& key_pair : hd_keypaths) {
         sigdata.misc_pubkeys.emplace(key_pair.first.GetID(), key_pair);
     }
-    if (m_tap_tree.has_value() && m_tap_internal_key.IsFullyValid()) {
-        TaprootSpendData spenddata = m_tap_tree->GetSpendData();
+    if (!m_tap_tree.empty() && m_tap_internal_key.IsFullyValid()) {
+        TaprootBuilder builder;
+        for (const auto& [depth, leaf_ver, script] : m_tap_tree) {
+            builder.Add((int)depth, script, (int)leaf_ver, /*track=*/true);
+        }
+        assert(builder.IsComplete());
+        builder.Finalize(m_tap_internal_key);
+        TaprootSpendData spenddata = builder.GetSpendData();
 
         sigdata.tr_spenddata.internal_key = m_tap_internal_key;
         sigdata.tr_spenddata.Merge(spenddata);
@@ -244,7 +250,7 @@ void PSBTOutput::FromSignatureData(const SignatureData& sigdata)
         m_tap_internal_key = sigdata.tr_spenddata.internal_key;
     }
     if (sigdata.tr_builder.has_value()) {
-        m_tap_tree = sigdata.tr_builder;
+        m_tap_tree = sigdata.tr_builder->GetTreeTuples();
     }
     for (const auto& [pubkey, leaf_origin] : sigdata.taproot_misc_pubkeys) {
         m_tap_bip32_paths.emplace(pubkey, leaf_origin);
@@ -265,7 +271,7 @@ void PSBTOutput::Merge(const PSBTOutput& output)
     if (redeem_script.empty() && !output.redeem_script.empty()) redeem_script = output.redeem_script;
     if (witness_script.empty() && !output.witness_script.empty()) witness_script = output.witness_script;
     if (m_tap_internal_key.IsNull() && !output.m_tap_internal_key.IsNull()) m_tap_internal_key = output.m_tap_internal_key;
-    if (!m_tap_tree.has_value() && output.m_tap_tree.has_value()) m_tap_tree = output.m_tap_tree;
+    if (m_tap_tree.empty() && !output.m_tap_tree.empty()) m_tap_tree = output.m_tap_tree;
 }
 bool PSBTInputSigned(const PSBTInput& input)
 {
diff --git a/src/psbt.h b/src/psbt.h
@@ -713,7 +713,7 @@ struct PSBTOutput
     CScript witness_script;
     std::map<CPubKey, KeyOriginInfo> hd_keypaths;
     XOnlyPubKey m_tap_internal_key;
-    std::optional<TaprootBuilder> m_tap_tree;
+    std::vector<std::tuple<uint8_t, uint8_t, CScript>> m_tap_tree;
     std::map<XOnlyPubKey, std::pair<std::set<uint256>, KeyOriginInfo>> m_tap_bip32_paths;
     std::map<std::vector<unsigned char>, std::vector<unsigned char>> unknown;
     std::set<PSBTProprietary> m_proprietary;
@@ -754,15 +754,11 @@ struct PSBTOutput
         }
 
         // Write taproot tree
-        if (m_tap_tree.has_value()) {
+        if (!m_tap_tree.empty()) {
             SerializeToVector(s, PSBT_OUT_TAP_TREE);
             std::vector<unsigned char> value;
             CVectorWriter s_value(s.GetType(), s.GetVersion(), value, 0);
-            const auto& tuples = m_tap_tree->GetTreeTuples();
-            for (const auto& tuple : tuples) {
-                uint8_t depth = std::get<0>(tuple);
-                uint8_t leaf_ver = std::get<1>(tuple);
-                CScript script = std::get<2>(tuple);
+            for (const auto& [depth, leaf_ver, script] : m_tap_tree) {
                 s_value << depth;
                 s_value << leaf_ver;
                 s_value << script;
@@ -858,13 +854,13 @@ struct PSBTOutput
                     } else if (key.size() != 1) {
                         throw std::ios_base::failure("Output Taproot tree key is more than one byte type");
                     }
-                    m_tap_tree.emplace();
                     std::vector<unsigned char> tree_v;
                     s >> tree_v;
                     SpanReader s_tree(s.GetType(), s.GetVersion(), tree_v);
                     if (s_tree.empty()) {
                         throw std::ios_base::failure("Output Taproot tree must not be empty");
                     }
+                    TaprootBuilder builder;
                     while (!s_tree.empty()) {
                         uint8_t depth;
                         uint8_t leaf_ver;
@@ -878,9 +874,10 @@ struct PSBTOutput
                         if ((leaf_ver & ~TAPROOT_LEAF_MASK) != 0) {
                             throw std::ios_base::failure("Output Taproot tree has a leaf with an invalid leaf version");
                         }
-                        m_tap_tree->Add((int)depth, script, (int)leaf_ver, true /* track */);
+                        m_tap_tree.push_back(std::make_tuple(depth, leaf_ver, script));
+                        builder.Add((int)depth, script, (int)leaf_ver, true /* track */);
                     }
-                    if (!m_tap_tree->IsComplete()) {
+                    if (!builder.IsComplete()) {
                         throw std::ios_base::failure("Output Taproot tree is malformed");
                     }
                     break;
@@ -934,11 +931,6 @@ struct PSBTOutput
             }
         }
 
-        // Finalize m_tap_tree so that all of the computed things are computed
-        if (m_tap_tree.has_value() && m_tap_tree->IsComplete() && m_tap_internal_key.IsFullyValid()) {
-            m_tap_tree->Finalize(m_tap_internal_key);
-        }
-
         if (!found_sep) {
             throw std::ios_base::failure("Separator is missing at the end of an output map");
         }
diff --git a/src/rpc/rawtransaction.cpp b/src/rpc/rawtransaction.cpp
@@ -1241,13 +1241,9 @@ static RPCHelpMan decodepsbt()
         }
 
         // Taproot tree
-        if (output.m_tap_tree.has_value()) {
+        if (!output.m_tap_tree.empty()) {
             UniValue tree(UniValue::VARR);
-            const auto& tuples = output.m_tap_tree->GetTreeTuples();
-            for (const auto& tuple : tuples) {
-                uint8_t depth = std::get<0>(tuple);
-                uint8_t leaf_ver = std::get<1>(tuple);
-                CScript script = std::get<2>(tuple);
+            for (const auto& [depth, leaf_ver, script] : output.m_tap_tree) {
                 UniValue elem(UniValue::VOBJ);
                 elem.pushKV("depth", (int)depth);
                 elem.pushKV("leaf_ver", (int)leaf_ver);
