rpc|llmq|test: Implement verifychainlock (#4119)

* llmq: Make CLSIG_REQUESTID_PREFIX available outside of quorums_chainlocks.cpp

* rpc: Implement `verifychainlock`

* test: Add rpc_verifychainlock.py

* rpc: Fix help text

Co-authored-by: UdjinM6 <UdjinM6@users.noreply.github.com>

Co-authored-by: UdjinM6 <UdjinM6@users.noreply.github.com>

src/llmq/quorums_chainlocks.cpp

@@ -17,7 +17,7 @@
 namespace llmq
 {
 
-static const std::string CLSIG_REQUESTID_PREFIX = "clsig";
+const std::string CLSIG_REQUESTID_PREFIX = "clsig";
 
 CChainLocksHandler* chainLocksHandler;
 

src/llmq/quorums_chainlocks.h

@@ -22,6 +22,8 @@ class CScheduler;
 namespace llmq
 {
 
+extern const std::string CLSIG_REQUESTID_PREFIX;
+
 class CChainLockSig
 {
 public:

src/rpc/rpcquorums.cpp

@@ -15,6 +15,10 @@
 #include <llmq/quorums_signing.h>
 #include <llmq/quorums_signing_shares.h>
 
+namespace llmq {
+extern const std::string CLSIG_REQUESTID_PREFIX;
+}
+
 void quorum_list_help()
 {
     throw std::runtime_error(
@@ -652,6 +656,48 @@ UniValue quorum(const JSONRPCRequest& request)
     }
 }
 
+void verifychainlock_help()
+{
+    throw std::runtime_error(
+            "verifychainlock \"blockHash\" \"signature\" ( blockHeight )\n"
+            "Test if a quorum signature is valid for a ChainLock.\n"
+            "\nArguments:\n"
+            "1. \"blockHash\"           (string, required) The block hash of the ChainLock.\n"
+            "2. \"signature\"           (string, required) The signature of the ChainLock.\n"
+            "3. blockHeight           (integer, optional) The height of the ChainLock. There will be an internal lookup of \"blockHash\" if this is not provided.\n"
+    );
+}
+
+UniValue verifychainlock(const JSONRPCRequest& request)
+{
+    if (request.fHelp || request.params.size() < 2 || request.params.size() > 3) {
+        verifychainlock_help();
+    }
+
+    const uint256 nBlockHash = ParseHashV(request.params[0], "blockHash");
+
+    CBLSSignature chainLockSig;
+    if (!chainLockSig.SetHexStr(request.params[1].get_str())) {
+        throw JSONRPCError(RPC_INVALID_PARAMETER, "invalid signature format");
+    }
+
+    int nBlockHeight;
+    if (request.params[2].isNull()) {
+        LOCK(cs_main);
+        const CBlockIndex* pIndex = LookupBlockIndex(nBlockHash);
+        if (pIndex == nullptr) {
+            throw JSONRPCError(RPC_INTERNAL_ERROR, "blockHash not found");
+        }
+        nBlockHeight = pIndex->nHeight;
+    } else {
+        nBlockHeight = ParseInt32V(request.params[2], "blockHeight");
+    }
+
+    const auto llmqType = Params().GetConsensus().llmqTypeChainLocks;
+    const uint256 nRequestId = ::SerializeHash(std::make_pair(llmq::CLSIG_REQUESTID_PREFIX, nBlockHeight));
+    return llmq::CSigningManager::VerifyRecoveredSig(llmqType, nBlockHeight, nRequestId, nBlockHash, chainLockSig);
+}
+
 void verifyislock_help()
 {
     throw std::runtime_error(
@@ -713,6 +759,7 @@ static const CRPCCommand commands[] =
 { //  category              name                      actor (function)
   //  --------------------- ------------------------  -----------------------
     { "evo",                "quorum",                 &quorum,                 {}  },
+    { "evo",                "verifychainlock",        &verifychainlock,        {"blockHash", "signature", "blockHeight"} },
     { "evo",                "verifyislock",           &verifyislock,           {"id", "txid", "signature", "maxHeight"}  },
 };
 

test/functional/rpc_verifychainlock.py

@@ -0,0 +1,61 @@
+#!/usr/bin/env python3
+# Copyright (c) 2021 The Dash Core developers
+# Distributed under the MIT software license, see the accompanying
+# file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+from test_framework.test_framework import DashTestFramework
+from test_framework.util import assert_raises_rpc_error
+
+'''
+rpc_verifychainlock.py
+
+Test verifychainlock rpc
+
+'''
+
+
+class RPCVerifyChainLockTest(DashTestFramework):
+    def set_test_params(self):
+        # -whitelist is needed to avoid the trickling logic on node0
+        self.set_dash_test_params(5, 3, [["-whitelist=127.0.0.1"], [], [], [], []], fast_dip3_enforcement=True)
+        self.set_dash_llmq_test_params(3, 2)
+
+    def run_test(self):
+        node0 = self.nodes[0]
+        node1 = self.nodes[1]
+        self.activate_dip8()
+        self.nodes[0].spork("SPORK_17_QUORUM_DKG_ENABLED", 0)
+        self.wait_for_sporks_same()
+        self.mine_quorum()
+        self.wait_for_chainlocked_block(node0, node0.generate(1)[0])
+        chainlock = node0.getbestchainlock()
+        block_hash = chainlock["blockhash"]
+        height = chainlock["height"]
+        chainlock_signature = chainlock["signature"]
+        # No "blockHeight"
+        assert node0.verifychainlock(block_hash, chainlock_signature)
+        # Invalid "blockHeight"
+        assert not node0.verifychainlock(block_hash, chainlock_signature, 0)
+        # Valid "blockHeight"
+        assert node0.verifychainlock(block_hash, chainlock_signature, height)
+        # Invalid "blockHash"
+        assert not node0.verifychainlock(node0.getblockhash(0), chainlock_signature, height)
+        # Isolate node1, mine a block on node0 and wait for its ChainLock
+        node1.setnetworkactive(False)
+        node0.generate(1)
+        self.wait_for_chainlocked_block(node0, node0.generate(1)[0])
+        chainlock = node0.getbestchainlock()
+        assert chainlock != node1.getbestchainlock()
+        block_hash = chainlock["blockhash"]
+        height = chainlock["height"]
+        chainlock_signature = chainlock["signature"]
+        # Now it should verify on node0 without "blockHeight" but fail on node1
+        assert node0.verifychainlock(block_hash, chainlock_signature)
+        assert_raises_rpc_error(-32603, "blockHash not found", node1.verifychainlock, block_hash, chainlock_signature)
+        # But they should still both verify with the height provided
+        assert node0.verifychainlock(block_hash, chainlock_signature, height)
+        assert node1.verifychainlock(block_hash, chainlock_signature, height)
+
+
+if __name__ == '__main__':
+    RPCVerifyChainLockTest().main()

test/functional/test_runner.py

@@ -162,6 +162,7 @@ BASE_SCRIPTS= [
     'rpc_masternode.py',
     'rpc_mnauth.py',
     'rpc_verifyislock.py',
+    'rpc_verifychainlock.py',
     'p2p_fingerprint.py',
     'rpc_platform_filter.py',
     'feature_dip0020_activation.py',