1 // Copyright (c) 2009-2020 The Bitcoin Core developers
2 // Distributed under the MIT software license, see the accompanying
3 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
4
5 #include <amount.h>
6 #include <coins.h>
7 #include <consensus/tx_verify.h>
8 #include <node/psbt.h>
9 #include <policy/policy.h>
10 #include <policy/settings.h>
11 #include <tinyformat.h>
12
13 #include <numeric>
14
AnalyzePSBT(PartiallySignedTransaction psbtx)15 PSBTAnalysis AnalyzePSBT(PartiallySignedTransaction psbtx)
16 {
17 // Go through each input and build status
18 PSBTAnalysis result;
19
20 bool calc_fee = true;
21
22 CAmount in_amt = 0;
23
24 result.inputs.resize(psbtx.tx->vin.size());
25
26 for (unsigned int i = 0; i < psbtx.tx->vin.size(); ++i) {
27 PSBTInput& input = psbtx.inputs[i];
28 PSBTInputAnalysis& input_analysis = result.inputs[i];
29
30 // We set next role here and ratchet backwards as required
31 input_analysis.next = PSBTRole::EXTRACTOR;
32
33 // Check for a UTXO
34 CTxOut utxo;
35 if (psbtx.GetInputUTXO(utxo, i)) {
36 if (!MoneyRange(utxo.nValue) || !MoneyRange(in_amt + utxo.nValue)) {
37 result.SetInvalid(strprintf("PSBT is not valid. Input %u has invalid value", i));
38 return result;
39 }
40 in_amt += utxo.nValue;
41 input_analysis.has_utxo = true;
42 } else {
43 if (input.non_witness_utxo && psbtx.tx->vin[i].prevout.n >= input.non_witness_utxo->vout.size()) {
44 result.SetInvalid(strprintf("PSBT is not valid. Input %u specifies invalid prevout", i));
45 return result;
46 }
47 input_analysis.has_utxo = false;
48 input_analysis.is_final = false;
49 input_analysis.next = PSBTRole::UPDATER;
50 calc_fee = false;
51 }
52
53 if (!utxo.IsNull() && utxo.scriptPubKey.IsUnspendable()) {
54 result.SetInvalid(strprintf("PSBT is not valid. Input %u spends unspendable output", i));
55 return result;
56 }
57
58 // Check if it is final
59 if (!utxo.IsNull() && !PSBTInputSigned(input)) {
60 input_analysis.is_final = false;
61
62 // Figure out what is missing
63 SignatureData outdata;
64 bool complete = SignPSBTInput(DUMMY_SIGNING_PROVIDER, psbtx, i, 1, &outdata);
65
66 // Things are missing
67 if (!complete) {
68 input_analysis.missing_pubkeys = outdata.missing_pubkeys;
69 input_analysis.missing_redeem_script = outdata.missing_redeem_script;
70 input_analysis.missing_witness_script = outdata.missing_witness_script;
71 input_analysis.missing_sigs = outdata.missing_sigs;
72
73 // If we are only missing signatures and nothing else, then next is signer
74 if (outdata.missing_pubkeys.empty() && outdata.missing_redeem_script.IsNull() && outdata.missing_witness_script.IsNull() && !outdata.missing_sigs.empty()) {
75 input_analysis.next = PSBTRole::SIGNER;
76 } else {
77 input_analysis.next = PSBTRole::UPDATER;
78 }
79 } else {
80 input_analysis.next = PSBTRole::FINALIZER;
81 }
82 } else if (!utxo.IsNull()){
83 input_analysis.is_final = true;
84 }
85 }
86
87 // Calculate next role for PSBT by grabbing "minimum" PSBTInput next role
88 result.next = PSBTRole::EXTRACTOR;
89 for (unsigned int i = 0; i < psbtx.tx->vin.size(); ++i) {
90 PSBTInputAnalysis& input_analysis = result.inputs[i];
91 result.next = std::min(result.next, input_analysis.next);
92 }
93 assert(result.next > PSBTRole::CREATOR);
94
95 if (calc_fee) {
96 // Get the output amount
97 CAmount out_amt = std::accumulate(psbtx.tx->vout.begin(), psbtx.tx->vout.end(), CAmount(0),
98 [](CAmount a, const CTxOut& b) {
99 if (!MoneyRange(a) || !MoneyRange(b.nValue) || !MoneyRange(a + b.nValue)) {
100 return CAmount(-1);
101 }
102 return a += b.nValue;
103 }
104 );
105 if (!MoneyRange(out_amt)) {
106 result.SetInvalid(strprintf("PSBT is not valid. Output amount invalid"));
107 return result;
108 }
109
110 // Get the fee
111 CAmount fee = in_amt - out_amt;
112 result.fee = fee;
113
114 // Estimate the size
115 CMutableTransaction mtx(*psbtx.tx);
116 CCoinsView view_dummy;
117 CCoinsViewCache view(&view_dummy);
118 bool success = true;
119
120 for (unsigned int i = 0; i < psbtx.tx->vin.size(); ++i) {
121 PSBTInput& input = psbtx.inputs[i];
122 Coin newcoin;
123
124 if (!SignPSBTInput(DUMMY_SIGNING_PROVIDER, psbtx, i, 1, nullptr, true) || !psbtx.GetInputUTXO(newcoin.out, i)) {
125 success = false;
126 break;
127 } else {
128 mtx.vin[i].scriptSig = input.final_script_sig;
129 mtx.vin[i].scriptWitness = input.final_script_witness;
130 newcoin.nHeight = 1;
131 view.AddCoin(psbtx.tx->vin[i].prevout, std::move(newcoin), true);
132 }
133 }
134
135 if (success) {
136 CTransaction ctx = CTransaction(mtx);
137 size_t size = GetVirtualTransactionSize(ctx, GetTransactionSigOpCost(ctx, view, STANDARD_SCRIPT_VERIFY_FLAGS));
138 result.estimated_vsize = size;
139 // Estimate fee rate
140 CFeeRate feerate(fee, size);
141 result.estimated_feerate = feerate;
142 }
143
144 }
145
146 return result;
147 }
148