2 files changed, 14 insertions, 0 deletions
diff --git a/src/interfaces/chain.cpp b/src/interfaces/chain.cpp
index cfaf79f709..1c1fbe7387 100644
--- a/src/interfaces/chain.cpp
+++ b/src/interfaces/chain.cpp
@@ -267,6 +267,14 @@ public:
         WAIT_LOCK(cs_main, lock);
         return FillBlock(LookupBlockIndex(hash), block, lock);
     }
+    bool findAncestorByHash(const uint256& block_hash, const uint256& ancestor_hash, const FoundBlock& ancestor_out) override
+    {
+        WAIT_LOCK(cs_main, lock);
+        const CBlockIndex* block = LookupBlockIndex(block_hash);
+        const CBlockIndex* ancestor = LookupBlockIndex(ancestor_hash);
+        if (block && ancestor && block->GetAncestor(ancestor->nHeight) != ancestor) ancestor = nullptr;
+        return FillBlock(ancestor, ancestor_out, lock);
+    }
     void findCoins(std::map<COutPoint, Coin>& coins) override { return FindCoins(m_node, coins); }
     double guessVerificationProgress(const uint256& block_hash) override
     {
diff --git a/src/interfaces/chain.h b/src/interfaces/chain.h
index 3778ab9a8b..7504f4cfb6 100644
--- a/src/interfaces/chain.h
+++ b/src/interfaces/chain.h
@@ -150,6 +150,12 @@ public:
     //! or contents.
     virtual bool findBlock(const uint256& hash, const FoundBlock& block={}) = 0;
 
+    //! Return whether block descends from a specified ancestor, and
+    //! optionally return ancestor information.
+    virtual bool findAncestorByHash(const uint256& block_hash,
+        const uint256& ancestor_hash,
+        const FoundBlock& ancestor_out={}) = 0;
+
     //! Look up unspent output information. Returns coins in the mempool and in
     //! the current chain UTXO set. Iterates through all the keys in the map and
     //! populates the values.