Bitcoin Core  27.99.0
P2P Digital Currency
external_signer.cpp
Go to the documentation of this file.
1 // Copyright (c) 2018-2022 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 <external_signer.h>
6 
7 #include <chainparams.h>
8 #include <common/run_command.h>
9 #include <core_io.h>
10 #include <psbt.h>
11 #include <util/strencodings.h>
12 
13 #include <algorithm>
14 #include <stdexcept>
15 #include <string>
16 #include <vector>
17 
18 ExternalSigner::ExternalSigner(const std::string& command, const std::string chain, const std::string& fingerprint, const std::string name): m_command(command), m_chain(chain), m_fingerprint(fingerprint), m_name(name) {}
19 
20 std::string ExternalSigner::NetworkArg() const
21 {
22  return " --chain " + m_chain;
23 }
24 
25 bool ExternalSigner::Enumerate(const std::string& command, std::vector<ExternalSigner>& signers, const std::string chain)
26 {
27  // Call <command> enumerate
28  const UniValue result = RunCommandParseJSON(command + " enumerate");
29  if (!result.isArray()) {
30  throw std::runtime_error(strprintf("'%s' received invalid response, expected array of signers", command));
31  }
32  for (const UniValue& signer : result.getValues()) {
33  // Check for error
34  const UniValue& error = signer.find_value("error");
35  if (!error.isNull()) {
36  if (!error.isStr()) {
37  throw std::runtime_error(strprintf("'%s' error", command));
38  }
39  throw std::runtime_error(strprintf("'%s' error: %s", command, error.getValStr()));
40  }
41  // Check if fingerprint is present
42  const UniValue& fingerprint = signer.find_value("fingerprint");
43  if (fingerprint.isNull()) {
44  throw std::runtime_error(strprintf("'%s' received invalid response, missing signer fingerprint", command));
45  }
46  const std::string& fingerprintStr{fingerprint.get_str()};
47  // Skip duplicate signer
48  bool duplicate = false;
49  for (const ExternalSigner& signer : signers) {
50  if (signer.m_fingerprint.compare(fingerprintStr) == 0) duplicate = true;
51  }
52  if (duplicate) break;
53  std::string name;
54  const UniValue& model_field = signer.find_value("model");
55  if (model_field.isStr() && model_field.getValStr() != "") {
56  name += model_field.getValStr();
57  }
58  signers.emplace_back(command, chain, fingerprintStr, name);
59  }
60  return true;
61 }
62 
63 UniValue ExternalSigner::DisplayAddress(const std::string& descriptor) const
64 {
65  return RunCommandParseJSON(m_command + " --fingerprint " + m_fingerprint + NetworkArg() + " displayaddress --desc " + descriptor);
66 }
67 
69 {
70  return RunCommandParseJSON(m_command + " --fingerprint " + m_fingerprint + NetworkArg() + " getdescriptors --account " + strprintf("%d", account));
71 }
72 
74 {
75  // Serialize the PSBT
76  DataStream ssTx{};
77  ssTx << psbtx;
78  // parse ExternalSigner master fingerprint
79  std::vector<unsigned char> parsed_m_fingerprint = ParseHex(m_fingerprint);
80  // Check if signer fingerprint matches any input master key fingerprint
81  auto matches_signer_fingerprint = [&](const PSBTInput& input) {
82  for (const auto& entry : input.hd_keypaths) {
83  if (parsed_m_fingerprint == MakeUCharSpan(entry.second.fingerprint)) return true;
84  }
85  for (const auto& entry : input.m_tap_bip32_paths) {
86  if (parsed_m_fingerprint == MakeUCharSpan(entry.second.second.fingerprint)) return true;
87  }
88  return false;
89  };
90 
91  if (!std::any_of(psbtx.inputs.begin(), psbtx.inputs.end(), matches_signer_fingerprint)) {
92  error = "Signer fingerprint " + m_fingerprint + " does not match any of the inputs:\n" + EncodeBase64(ssTx.str());
93  return false;
94  }
95 
96  const std::string command = m_command + " --stdin --fingerprint " + m_fingerprint + NetworkArg();
97  const std::string stdinStr = "signtx " + EncodeBase64(ssTx.str());
98 
99  const UniValue signer_result = RunCommandParseJSON(command, stdinStr);
100 
101  if (signer_result.find_value("error").isStr()) {
102  error = signer_result.find_value("error").get_str();
103  return false;
104  }
105 
106  if (!signer_result.find_value("psbt").isStr()) {
107  error = "Unexpected result from signer";
108  return false;
109  }
110 
111  PartiallySignedTransaction signer_psbtx;
112  std::string signer_psbt_error;
113  if (!DecodeBase64PSBT(signer_psbtx, signer_result.find_value("psbt").get_str(), signer_psbt_error)) {
114  error = strprintf("TX decode failed %s", signer_psbt_error);
115  return false;
116  }
117 
118  psbtx = signer_psbtx;
119 
120  return true;
121 }
const auto command
Double ended buffer combining vector and stream-like interfaces.
Definition: streams.h:147
Enables interaction with an external signing device or service, such as a hardware wallet.
std::string m_chain
Bitcoin mainnet, testnet, etc.
UniValue DisplayAddress(const std::string &descriptor) const
Display address on the device.
UniValue GetDescriptors(const int account)
Get receive and change Descriptor(s) from device for a given account.
bool SignTransaction(PartiallySignedTransaction &psbt, std::string &error)
Sign PartiallySignedTransaction on the device.
std::string NetworkArg() const
std::string m_fingerprint
Master key fingerprint of the signer.
std::string m_command
The command which handles interaction with the external signer.
static bool Enumerate(const std::string &command, std::vector< ExternalSigner > &signers, const std::string chain)
Obtain a list of signers.
ExternalSigner(const std::string &command, const std::string chain, const std::string &fingerprint, const std::string name)
const std::string & get_str() const
bool isArray() const
Definition: univalue.h:85
const UniValue & find_value(std::string_view key) const
Definition: univalue.cpp:233
bool isNull() const
Definition: univalue.h:79
const std::string & getValStr() const
Definition: univalue.h:68
const std::vector< UniValue > & getValues() const
bool isStr() const
Definition: univalue.h:83
CRPCCommand m_command
Definition: interfaces.cpp:517
bool DecodeBase64PSBT(PartiallySignedTransaction &psbt, const std::string &base64_tx, std::string &error)
Decode a base64ed PSBT into a PartiallySignedTransaction.
Definition: psbt.cpp:536
const char * name
Definition: rest.cpp:48
UniValue RunCommandParseJSON(const std::string &str_command, const std::string &str_std_in)
Execute a command which returns JSON, and parse the result.
Definition: run_command.cpp:16
constexpr auto MakeUCharSpan(V &&v) -> decltype(UCharSpanCast(Span{std::forward< V >(v)}))
Like the Span constructor, but for (const) unsigned char member types only.
Definition: span.h:304
std::vector< Byte > ParseHex(std::string_view hex_str)
Like TryParseHex, but returns an empty vector on invalid input.
Definition: strencodings.h:65
A structure for PSBTs which contain per-input information.
Definition: psbt.h:194
A version of CTransaction with the PSBT format.
Definition: psbt.h:947
std::vector< PSBTInput > inputs
Definition: psbt.h:952
#define strprintf
Format arguments and return the string or write to given std::ostream (see tinyformat::format doc for...
Definition: tinyformat.h:1162
std::string EncodeBase64(Span< const unsigned char > input)