Implement analyzepsbt RPC and tests

1 files changed, 198 insertions, 0 deletions

diff --git a/src/rpc/rawtransaction.cpp b/src/rpc/rawtransaction.cpp
index 866158e003..ac41207404 100644
--- a/src/rpc/rawtransaction.cpp
+++ b/src/rpc/rawtransaction.cpp
@@ -7,6 +7,7 @@
 #include <coins.h>
 #include <compat/byteswap.h>
 #include <consensus/validation.h>
+#include <consensus/tx_verify.h>
 #include <core_io.h>
 #include <index/txindex.h>
 #include <init.h>
@@ -30,6 +31,8 @@
 #include <validation.h>
 #include <validationinterface.h>
 
+
+#include <numeric>
 #include <stdint.h>
 
 #include <univalue.h>
@@ -1829,6 +1832,200 @@ UniValue joinpsbts(const JSONRPCRequest& request)
     return EncodeBase64((unsigned char*)ssTx.data(), ssTx.size());
 }
 
+UniValue analyzepsbt(const JSONRPCRequest& request)
+{
+    if (request.fHelp || request.params.size() != 1) {
+        throw std::runtime_error(
+            RPCHelpMan{"analyzepsbt",
+            "\nAnalyzes and provides information about the current status of a PSBT and its inputs\n",
+            {
+                {"psbt", RPCArg::Type::STR, RPCArg::Optional::NO, "A base64 string of a PSBT"}
+            },
+            RPCResult {
+                "{\n"
+                "  \"inputs\" : [                      (array of json objects)\n"
+                "    {\n"
+                "      \"has_utxo\" : true|false     (boolean) Whether a UTXO is provided\n"
+                "      \"is_final\" : true|false     (boolean) Whether the input is finalized\n"
+                "      \"missing\" : {               (json object, optional) Things that are missing that are required to complete this input\n"
+                "        \"pubkeys\" : [             (array)\n"
+                "          \"keyid\"                 (string) Public key ID, hash160 of the public key, of a public key whose BIP 32 derivation path is missing\n"
+                "        ]\n"
+                "        \"signatures\" : [          (array)\n"
+                "          \"keyid\"                 (string) Public key ID, hash160 of the public key, of a public key whose signature is missing\n"
+                "        ]\n"
+                "        \"redeemscript\" : \"hash\"   (string) Hash160 of the redeemScript that is missing\n"
+                "        \"witnessscript\" : \"hash\"  (string) SHA256 of the witnessScript that is missing\n"
+                "      }\n"
+                "      \"next\" : \"role\"           (string) Role of the next person that this input needs to go to\n"
+                "    }\n"
+                "    ,...\n"
+                "  ]\n"
+                "  \"estimated_vsize\" : vsize       (numeric) Estimated vsize of the final signed transaction\n"
+                "  \"estimated_feerate\" : feerate   (numeric, optional) Estimated feerate of the final signed transaction. Shown only if all UTXO slots in the PSBT have been filled.\n"
+                "  \"fee\" : fee                     (numeric, optional) The transaction fee paid. Shown only if all UTXO slots in the PSBT have been filled.\n"
+                "  \"next\" : \"role\"                 (string) Role of the next person that this psbt needs to go to\n"
+                "}\n"
+            },
+            RPCExamples {
+                HelpExampleCli("analyzepsbt", "\"psbt\"")
+            }}.ToString());
+    }
+
+    RPCTypeCheck(request.params, {UniValue::VSTR});
+
+    // Unserialize the transaction
+    PartiallySignedTransaction psbtx;
+    std::string error;
+    if (!DecodeBase64PSBT(psbtx, request.params[0].get_str(), error)) {
+        throw JSONRPCError(RPC_DESERIALIZATION_ERROR, strprintf("TX decode failed %s", error));
+    }
+
+    // Go through each input and build status
+    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];
+        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;
+        }
+
+        // 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");
+            }
+        } else if (!utxo.IsNull()){
+            input_univ.pushKV("is_final", true);
+        }
+        inputs_result.push_back(input_univ);
+    }
+    result.pushKV("inputs", inputs_result);
+
+    if (all_final) {
+        only_missing_sigs = false;
+        result.pushKV("next", "extractor");
+    }
+    if (calc_fee) {
+        // Get the output amount
+        CAmount out_amt = std::accumulate(psbtx.tx->vout.begin(), psbtx.tx->vout.end(), 0,
+            [](int 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", feerate.ToString());
+        }
+        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");
+    }
+    return result;
+}
+
 // clang-format off
 static const CRPCCommand commands[] =
 { //  category              name                            actor (function)            argNames
@@ -1849,6 +2046,7 @@ static const CRPCCommand commands[] =
     { "rawtransactions",    "converttopsbt",                &converttopsbt,             {"hexstring","permitsigdata","iswitness"} },
     { "rawtransactions",    "utxoupdatepsbt",               &utxoupdatepsbt,            {"psbt"} },
     { "rawtransactions",    "joinpsbts",                    &joinpsbts,                 {"txs"} },
+    { "rawtransactions",    "analyzepsbt",                  &analyzepsbt,               {"psbt"} },
 
     { "blockchain",         "gettxoutproof",                &gettxoutproof,             {"txids", "blockhash"} },
     { "blockchain",         "verifytxoutproof",             &verifytxoutproof,          {"proof"} },