aboutsummaryrefslogtreecommitdiff
path: root/src/node/psbt.cpp
blob: 26023d5a4cb06c93719b2f9a511c05b54fe462e0 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
// Copyright (c) 2009-2021 The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.

#include <coins.h>
#include <consensus/amount.h>
#include <consensus/tx_verify.h>
#include <node/psbt.h>
#include <policy/policy.h>
#include <policy/settings.h>
#include <tinyformat.h>

#include <numeric>

PSBTAnalysis AnalyzePSBT(PartiallySignedTransaction psbtx)
{
    // Go through each input and build status
    PSBTAnalysis result;

    bool calc_fee = true;

    CAmount in_amt = 0;

    result.inputs.resize(psbtx.tx->vin.size());

    const PrecomputedTransactionData txdata = PrecomputePSBTData(psbtx);

    for (unsigned int i = 0; i < psbtx.tx->vin.size(); ++i) {
        PSBTInput& input = psbtx.inputs[i];
        PSBTInputAnalysis& input_analysis = result.inputs[i];

        // We set next role here and ratchet backwards as required
        input_analysis.next = PSBTRole::EXTRACTOR;

        // Check for a UTXO
        CTxOut utxo;
        if (psbtx.GetInputUTXO(utxo, i)) {
            if (!MoneyRange(utxo.nValue) || !MoneyRange(in_amt + utxo.nValue)) {
                result.SetInvalid(strprintf("PSBT is not valid. Input %u has invalid value", i));
                return result;
            }
            in_amt += utxo.nValue;
            input_analysis.has_utxo = true;
        } else {
            if (input.non_witness_utxo && psbtx.tx->vin[i].prevout.n >= input.non_witness_utxo->vout.size()) {
                result.SetInvalid(strprintf("PSBT is not valid. Input %u specifies invalid prevout", i));
                return result;
            }
            input_analysis.has_utxo = false;
            input_analysis.is_final = false;
            input_analysis.next = PSBTRole::UPDATER;
            calc_fee = false;
        }

        if (!utxo.IsNull() && utxo.scriptPubKey.IsUnspendable()) {
            result.SetInvalid(strprintf("PSBT is not valid. Input %u spends unspendable output", i));
            return result;
        }

        // Check if it is final
        if (!utxo.IsNull() && !PSBTInputSigned(input)) {
            input_analysis.is_final = false;

            // Figure out what is missing
            SignatureData outdata;
            bool complete = SignPSBTInput(DUMMY_SIGNING_PROVIDER, psbtx, i, &txdata, 1, &outdata);

            // Things are missing
            if (!complete) {
                input_analysis.missing_pubkeys = outdata.missing_pubkeys;
                input_analysis.missing_redeem_script = outdata.missing_redeem_script;
                input_analysis.missing_witness_script = outdata.missing_witness_script;
                input_analysis.missing_sigs = outdata.missing_sigs;

                // 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_analysis.next = PSBTRole::SIGNER;
                } else {
                    input_analysis.next = PSBTRole::UPDATER;
                }
            } else {
                input_analysis.next = PSBTRole::FINALIZER;
            }
        } else if (!utxo.IsNull()){
            input_analysis.is_final = true;
        }
    }

    // Calculate next role for PSBT by grabbing "minimum" PSBTInput next role
    result.next = PSBTRole::EXTRACTOR;
    for (unsigned int i = 0; i < psbtx.tx->vin.size(); ++i) {
        PSBTInputAnalysis& input_analysis = result.inputs[i];
        result.next = std::min(result.next, input_analysis.next);
    }
    assert(result.next > PSBTRole::CREATOR);

    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) {
                if (!MoneyRange(a) || !MoneyRange(b.nValue) || !MoneyRange(a + b.nValue)) {
                    return CAmount(-1);
                }
                return a += b.nValue;
            }
        );
        if (!MoneyRange(out_amt)) {
            result.SetInvalid("PSBT is not valid. Output amount invalid");
            return result;
        }

        // Get the fee
        CAmount fee = in_amt - out_amt;
        result.fee = fee;

        // 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];
            Coin newcoin;

            if (!SignPSBTInput(DUMMY_SIGNING_PROVIDER, psbtx, i, nullptr, 1) || !psbtx.GetInputUTXO(newcoin.out, i)) {
                success = false;
                break;
            } else {
                mtx.vin[i].scriptSig = input.final_script_sig;
                mtx.vin[i].scriptWitness = input.final_script_witness;
                newcoin.nHeight = 1;
                view.AddCoin(psbtx.tx->vin[i].prevout, std::move(newcoin), true);
            }
        }

        if (success) {
            CTransaction ctx = CTransaction(mtx);
            size_t size = GetVirtualTransactionSize(ctx, GetTransactionSigOpCost(ctx, view, STANDARD_SCRIPT_VERIFY_FLAGS));
            result.estimated_vsize = size;
            // Estimate fee rate
            CFeeRate feerate(fee, size);
            result.estimated_feerate = feerate;
        }

    }

    return result;
}