txoutproof.cpp raw
1 // Copyright (c) 2010 Satoshi Nakamoto
2 // Copyright (c) 2009-present The Bitcoin Core developers
3 // Distributed under the MIT software license, see the accompanying
4 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
5
6 #include <chain.h>
7 #include <chainparams.h>
8 #include <coins.h>
9 #include <index/txindex.h>
10 #include <merkleblock.h>
11 #include <node/blockstorage.h>
12 #include <primitives/transaction.h>
13 #include <rpc/blockchain.h>
14 #include <rpc/server.h>
15 #include <rpc/server_util.h>
16 #include <rpc/util.h>
17 #include <univalue.h>
18 #include <util/strencodings.h>
19 #include <validation.h>
20
21 using node::GetTransaction;
22
23 static RPCMethod gettxoutproof()
24 {
25 return RPCMethod{
26 "gettxoutproof",
27 "Returns a hex-encoded proof that \"txid\" was included in a block.\n"
28 "\nNOTE: By default this function only works sometimes. This is when there is an\n"
29 "unspent output in the utxo for this transaction. To make it always work,\n"
30 "you need to maintain a transaction index, using the -txindex command line option or\n"
31 "specify the block in which the transaction is included manually (by blockhash).\n",
32 {
33 {"txids", RPCArg::Type::ARR, RPCArg::Optional::NO, "The txids to filter",
34 {
35 {"txid", RPCArg::Type::STR_HEX, RPCArg::Optional::OMITTED, "A transaction hash"},
36 },
37 },
38 {"blockhash", RPCArg::Type::STR_HEX, RPCArg::Optional::OMITTED, "If specified, looks for txid in the block with this hash"},
39 },
40 RPCResult{
41 RPCResult::Type::STR, "data", "A string that is a serialized, hex-encoded data for the proof."
42 },
43 RPCExamples{""},
44 [](const RPCMethod& self, const JSONRPCRequest& request) -> UniValue
45 {
46 std::set<Txid> setTxids;
47 UniValue txids = request.params[0].get_array();
48 if (txids.empty()) {
49 throw JSONRPCError(RPC_INVALID_PARAMETER, "Parameter 'txids' cannot be empty");
50 }
51 for (unsigned int idx = 0; idx < txids.size(); idx++) {
52 auto ret{setTxids.insert(Txid::FromUint256(ParseHashV(txids[idx], "txid")))};
53 if (!ret.second) {
54 throw JSONRPCError(RPC_INVALID_PARAMETER, std::string("Invalid parameter, duplicated txid: ") + txids[idx].get_str());
55 }
56 }
57
58 const CBlockIndex* pblockindex = nullptr;
59 uint256 hashBlock;
60 ChainstateManager& chainman = EnsureAnyChainman(request.context);
61 if (!request.params[1].isNull()) {
62 LOCK(cs_main);
63 hashBlock = ParseHashV(request.params[1], "blockhash");
64 pblockindex = chainman.m_blockman.LookupBlockIndex(hashBlock);
65 if (!pblockindex) {
66 throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Block not found");
67 }
68 } else {
69 LOCK(cs_main);
70 Chainstate& active_chainstate = chainman.ActiveChainstate();
71
72 // Loop through txids and try to find which block they're in. Exit loop once a block is found.
73 for (const auto& tx : setTxids) {
74 const Coin& coin{AccessByTxid(active_chainstate.CoinsTip(), tx)};
75 if (!coin.IsSpent()) {
76 pblockindex = active_chainstate.m_chain[coin.nHeight];
77 break;
78 }
79 }
80 }
81
82
83 // Allow txindex to catch up if we need to query it and before we acquire cs_main.
84 if (g_txindex && !pblockindex) {
85 g_txindex->BlockUntilSyncedToCurrentChain();
86 }
87
88 if (pblockindex == nullptr) {
89 const CTransactionRef tx = GetTransaction(/*block_index=*/nullptr, /*mempool=*/nullptr, *setTxids.begin(), chainman.m_blockman, hashBlock);
90 if (!tx || hashBlock.IsNull()) {
91 throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Transaction not yet in block");
92 }
93
94 LOCK(cs_main);
95 pblockindex = chainman.m_blockman.LookupBlockIndex(hashBlock);
96 if (!pblockindex) {
97 throw JSONRPCError(RPC_INTERNAL_ERROR, "Transaction index corrupt");
98 }
99 }
100
101 {
102 LOCK(cs_main);
103 CheckBlockDataAvailability(chainman.m_blockman, *pblockindex, /*check_for_undo=*/false);
104 }
105 CBlock block;
106 if (!chainman.m_blockman.ReadBlock(block, *pblockindex)) {
107 throw JSONRPCError(RPC_INTERNAL_ERROR, "Can't read block from disk");
108 }
109
110 unsigned int ntxFound = 0;
111 for (const auto& tx : block.vtx) {
112 if (setTxids.contains(tx->GetHash())) {
113 ntxFound++;
114 }
115 }
116 if (ntxFound != setTxids.size()) {
117 throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Not all transactions found in specified or retrieved block");
118 }
119
120 DataStream ssMB{};
121 CMerkleBlock mb(block, setTxids);
122 ssMB << mb;
123 std::string strHex = HexStr(ssMB);
124 return strHex;
125 },
126 };
127 }
128
129 static RPCMethod verifytxoutproof()
130 {
131 return RPCMethod{
132 "verifytxoutproof",
133 "Verifies that a proof points to a transaction in a block, returning the transaction it commits to\n"
134 "and throwing an RPC error if the block is not in our best chain\n",
135 {
136 {"proof", RPCArg::Type::STR_HEX, RPCArg::Optional::NO, "The hex-encoded proof generated by gettxoutproof"},
137 },
138 RPCResult{
139 RPCResult::Type::ARR, "", "",
140 {
141 {RPCResult::Type::STR_HEX, "txid", "The txid(s) which the proof commits to, or empty array if the proof cannot be validated."},
142 }
143 },
144 RPCExamples{""},
145 [](const RPCMethod& self, const JSONRPCRequest& request) -> UniValue
146 {
147 CMerkleBlock merkleBlock;
148 SpanReader{ParseHexV(request.params[0], "proof")} >> merkleBlock;
149
150 UniValue res(UniValue::VARR);
151
152 std::vector<Txid> vMatch;
153 std::vector<unsigned int> vIndex;
154 if (merkleBlock.txn.ExtractMatches(vMatch, vIndex) != merkleBlock.header.hashMerkleRoot)
155 return res;
156
157 ChainstateManager& chainman = EnsureAnyChainman(request.context);
158 LOCK(cs_main);
159
160 const CBlockIndex* pindex = chainman.m_blockman.LookupBlockIndex(merkleBlock.header.GetHash());
161 if (!pindex || !chainman.ActiveChain().Contains(*pindex) || pindex->nTx == 0) {
162 throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Block not found in chain");
163 }
164
165 // Check if proof is valid, only add results if so
166 if (pindex->nTx == merkleBlock.txn.GetNumTransactions()) {
167 for (const auto& txid : vMatch) {
168 res.push_back(txid.GetHex());
169 }
170 }
171
172 return res;
173 },
174 };
175 }
176
177 void RegisterTxoutProofRPCCommands(CRPCTable& t)
178 {
179 static const CRPCCommand commands[]{
180 {"blockchain", &gettxoutproof},
181 {"blockchain", &verifytxoutproof},
182 };
183 for (const auto& c : commands) {
184 t.appendCommand(c.name, &c);
185 }
186 }
187