Merge #15508: Refactor analyzepsbt for use outside RPC code

892eff05f1 Add documentation of struct PSBTAnalysis et al (Glenn Willen)
ef22fe8c1f Refactor analyzepsbt for use outside RPC code (Glenn Willen)
afd20a25f2 Move PSBT decoding functions from core_io to psbt.cpp (Glenn Willen)

Pull request description:

  Refactor the analyzepsbt RPC into (1) an AnalyzePSBT function, which returns
  its output as a new strongly-typed PSBTAnalysis struct, and (2) a thin wrapper
  which converts the struct into a UniValue for RPC use.

  ----

  As with my previous refactoring PR, I need this because I am creating a dependency on this code from the GUI. Per discussion in #bitcoin-core-dev on IRC, since we don't want to create a dependency on UniValue in anything outside RPC, I introduced some new structs to hold the info we get when analyzing a PSBT. For the field types, I used whatever types are already used internally for this data (e.g. CAmount, CFeeRate, CKeyID), and only convert to int/string etc. in the wrapper.

  @achow101, maybe take the first look? :-)

ACKs for commit 892eff:
  sipa:
    utACK 892eff05f115c0b002d0e0b6ffc3ab418480d25c
  achow101:
    utACK 892eff05f115c0b002d0e0b6ffc3ab418480d25c
  ryanofsky:
    utACK 892eff05f115c0b002d0e0b6ffc3ab418480d25c. Just small cleanups since the last review: removing unneeded include, forward decl, adding const ref

Tree-SHA512: eb278b0a82717ebc3eb0c08dc5bb4eefb996a317a6a3a8ecf51cd88110ddbb188ad3482cdd9563e557995e73aca5a282c1f6e352bc598155f1203b7b46fe5dee

1 files changed, 36 insertions, 128 deletions

diff --git a/src/rpc/rawtransaction.cpp b/src/rpc/rawtransaction.cpp
index a68ad67ae5..8d9c207011 100644
--- a/src/rpc/rawtransaction.cpp
+++ b/src/rpc/rawtransaction.cpp
@@ -1943,148 +1943,56 @@ UniValue analyzepsbt(const JSONRPCRequest& request)
         throw JSONRPCError(RPC_DESERIALIZATION_ERROR, strprintf("TX decode failed %s", error));
     }
 
-    // Go through each input and build status
+    PSBTAnalysis psbta = AnalyzePSBT(psbtx);
+
     UniValue result(UniValue::VOBJ);
     UniValue inputs_result(UniValue::VARR);
-    bool calc_fee = true;
-    bool all_final = true;
-    bool only_missing_sigs = true;
-    bool only_missing_final = false;
-    CAmount in_amt = 0;
-    for (unsigned int i = 0; i < psbtx.tx->vin.size(); ++i) {
-        PSBTInput& input = psbtx.inputs[i];
+    for (const auto& input : psbta.inputs) {
         UniValue input_univ(UniValue::VOBJ);
         UniValue missing(UniValue::VOBJ);
 
-        // Check for a UTXO
-        CTxOut utxo;
-        if (psbtx.GetInputUTXO(utxo, i)) {
-            in_amt += utxo.nValue;
-            input_univ.pushKV("has_utxo", true);
-        } else {
-            input_univ.pushKV("has_utxo", false);
-            input_univ.pushKV("is_final", false);
-            input_univ.pushKV("next", "updater");
-            calc_fee = false;
-        }
+        input_univ.pushKV("has_utxo", input.has_utxo);
+        input_univ.pushKV("is_final", input.is_final);
+        input_univ.pushKV("next", PSBTRoleName(input.next));
 
-        // Check if it is final
-        if (!utxo.IsNull() && !PSBTInputSigned(input)) {
-            input_univ.pushKV("is_final", false);
-            all_final = false;
-
-            // Figure out what is missing
-            SignatureData outdata;
-            bool complete = SignPSBTInput(DUMMY_SIGNING_PROVIDER, psbtx, i, 1, &outdata);
-
-            // Things are missing
-            if (!complete) {
-                if (!outdata.missing_pubkeys.empty()) {
-                    // Missing pubkeys
-                    UniValue missing_pubkeys_univ(UniValue::VARR);
-                    for (const CKeyID& pubkey : outdata.missing_pubkeys) {
-                        missing_pubkeys_univ.push_back(HexStr(pubkey));
-                    }
-                    missing.pushKV("pubkeys", missing_pubkeys_univ);
-                }
-                if (!outdata.missing_redeem_script.IsNull()) {
-                    // Missing redeemScript
-                    missing.pushKV("redeemscript", HexStr(outdata.missing_redeem_script));
-                }
-                if (!outdata.missing_witness_script.IsNull()) {
-                    // Missing witnessScript
-                    missing.pushKV("witnessscript", HexStr(outdata.missing_witness_script));
-                }
-                if (!outdata.missing_sigs.empty()) {
-                    // Missing sigs
-                    UniValue missing_sigs_univ(UniValue::VARR);
-                    for (const CKeyID& pubkey : outdata.missing_sigs) {
-                        missing_sigs_univ.push_back(HexStr(pubkey));
-                    }
-                    missing.pushKV("signatures", missing_sigs_univ);
-                }
-                input_univ.pushKV("missing", missing);
-
-                // If we are only missing signatures and nothing else, then next is signer
-                if (outdata.missing_pubkeys.empty() && outdata.missing_redeem_script.IsNull() && outdata.missing_witness_script.IsNull() && !outdata.missing_sigs.empty()) {
-                    input_univ.pushKV("next", "signer");
-                } else {
-                    only_missing_sigs = false;
-                    input_univ.pushKV("next", "updater");
-                }
-            } else {
-                only_missing_final = true;
-                input_univ.pushKV("next", "finalizer");
+        if (!input.missing_pubkeys.empty()) {
+            UniValue missing_pubkeys_univ(UniValue::VARR);
+            for (const CKeyID& pubkey : input.missing_pubkeys) {
+                missing_pubkeys_univ.push_back(HexStr(pubkey));
             }
-        } else if (!utxo.IsNull()){
-            input_univ.pushKV("is_final", true);
+            missing.pushKV("pubkeys", missing_pubkeys_univ);
+        }
+        if (!input.missing_redeem_script.IsNull()) {
+            missing.pushKV("redeemscript", HexStr(input.missing_redeem_script));
+        }
+        if (!input.missing_witness_script.IsNull()) {
+            missing.pushKV("witnessscript", HexStr(input.missing_witness_script));
+        }
+        if (!input.missing_sigs.empty()) {
+            UniValue missing_sigs_univ(UniValue::VARR);
+            for (const CKeyID& pubkey : input.missing_sigs) {
+                missing_sigs_univ.push_back(HexStr(pubkey));
+            }
+            missing.pushKV("signatures", missing_sigs_univ);
+        }
+        if (!missing.getKeys().empty()) {
+            input_univ.pushKV("missing", missing);
         }
         inputs_result.push_back(input_univ);
     }
     result.pushKV("inputs", inputs_result);
 
-    if (all_final) {
-        only_missing_sigs = false;
-        result.pushKV("next", "extractor");
+    if (psbta.estimated_vsize != nullopt) {
+        result.pushKV("estimated_vsize", (int)*psbta.estimated_vsize);
     }
-    if (calc_fee) {
-        // Get the output amount
-        CAmount out_amt = std::accumulate(psbtx.tx->vout.begin(), psbtx.tx->vout.end(), CAmount(0),
-            [](CAmount a, const CTxOut& b) {
-                return a += b.nValue;
-            }
-        );
-
-        // Get the fee
-        CAmount fee = in_amt - out_amt;
-
-        // Estimate the size
-        CMutableTransaction mtx(*psbtx.tx);
-        CCoinsView view_dummy;
-        CCoinsViewCache view(&view_dummy);
-        bool success = true;
-
-        for (unsigned int i = 0; i < psbtx.tx->vin.size(); ++i) {
-            PSBTInput& input = psbtx.inputs[i];
-            if (SignPSBTInput(DUMMY_SIGNING_PROVIDER, psbtx, i, 1, nullptr, true)) {
-                mtx.vin[i].scriptSig = input.final_script_sig;
-                mtx.vin[i].scriptWitness = input.final_script_witness;
-
-                Coin newcoin;
-                if (!psbtx.GetInputUTXO(newcoin.out, i)) {
-                    success = false;
-                    break;
-                }
-                newcoin.nHeight = 1;
-                view.AddCoin(psbtx.tx->vin[i].prevout, std::move(newcoin), true);
-            } else {
-                success = false;
-                break;
-            }
-        }
-
-        if (success) {
-            CTransaction ctx = CTransaction(mtx);
-            size_t size = GetVirtualTransactionSize(ctx, GetTransactionSigOpCost(ctx, view, STANDARD_SCRIPT_VERIFY_FLAGS));
-            result.pushKV("estimated_vsize", (int)size);
-            // Estimate fee rate
-            CFeeRate feerate(fee, size);
-            result.pushKV("estimated_feerate", ValueFromAmount(feerate.GetFeePerK()));
-        }
-        result.pushKV("fee", ValueFromAmount(fee));
-
-        if (only_missing_sigs) {
-            result.pushKV("next", "signer");
-        } else if (only_missing_final) {
-            result.pushKV("next", "finalizer");
-        } else if (all_final) {
-            result.pushKV("next", "extractor");
-        } else {
-            result.pushKV("next", "updater");
-        }
-    } else {
-        result.pushKV("next", "updater");
+    if (psbta.estimated_feerate != nullopt) {
+        result.pushKV("estimated_feerate", ValueFromAmount(psbta.estimated_feerate->GetFeePerK()));
     }
+    if (psbta.fee != nullopt) {
+        result.pushKV("fee", ValueFromAmount(*psbta.fee));
+    }
+    result.pushKV("next", PSBTRoleName(psbta.next));
+
     return result;
 }