From 088e38d3bbea9694b319bc34e0d2e70d210c38b4 Mon Sep 17 00:00:00 2001
From: Sebastian Falbesoner <sebastian.falbesoner@gmail.com>
Date: Tue, 23 Aug 2022 16:10:59 +0200
Subject: [PATCH] add chain interface methods for using BIP 157 block filters

This is useful for speeding up wallet rescans and is based on an
earlier version from PR #15845 ("wallet: Fast rescan with BIP157 block
filters"), which was never merged.

Co-authored-by: MacroFake <falke.marco@gmail.com>
---
 src/interfaces/chain.h  |  8 ++++++++
 src/node/interfaces.cpp | 16 ++++++++++++++++
 2 files changed, 24 insertions(+)

diff --git a/src/interfaces/chain.h b/src/interfaces/chain.h
index 5fc0e540a94..7a3d88b18f5 100644
--- a/src/interfaces/chain.h
+++ b/src/interfaces/chain.h
@@ -5,6 +5,7 @@
 #ifndef BITCOIN_INTERFACES_CHAIN_H
 #define BITCOIN_INTERFACES_CHAIN_H
 
+#include <blockfilter.h>
 #include <primitives/transaction.h> // For CTransactionRef
 #include <util/settings.h>          // For util::SettingsValue
 
@@ -143,6 +144,13 @@ public:
     //! or one of its ancestors.
     virtual std::optional<int> findLocatorFork(const CBlockLocator& locator) = 0;
 
+    //! Returns whether a block filter index is available.
+    virtual bool hasBlockFilterIndex(BlockFilterType filter_type) = 0;
+
+    //! Returns whether any of the elements match the block via a BIP 157 block filter
+    //! or std::nullopt if the block filter for this block couldn't be found.
+    virtual std::optional<bool> blockFilterMatchesAny(BlockFilterType filter_type, const uint256& block_hash, const GCSFilter::ElementSet& filter_set) = 0;
+
     //! Return whether node has the block and optionally return block metadata
     //! or contents.
     virtual bool findBlock(const uint256& hash, const FoundBlock& block={}) = 0;
diff --git a/src/node/interfaces.cpp b/src/node/interfaces.cpp
index 8a0011a629e..979c6254633 100644
--- a/src/node/interfaces.cpp
+++ b/src/node/interfaces.cpp
@@ -4,10 +4,12 @@
 
 #include <addrdb.h>
 #include <banman.h>
+#include <blockfilter.h>
 #include <chain.h>
 #include <chainparams.h>
 #include <deploymentstatus.h>
 #include <external_signer.h>
+#include <index/blockfilterindex.h>
 #include <init.h>
 #include <interfaces/chain.h>
 #include <interfaces/handler.h>
@@ -536,6 +538,20 @@ public:
         }
         return std::nullopt;
     }
+    bool hasBlockFilterIndex(BlockFilterType filter_type) override
+    {
+        return GetBlockFilterIndex(filter_type) != nullptr;
+    }
+    std::optional<bool> blockFilterMatchesAny(BlockFilterType filter_type, const uint256& block_hash, const GCSFilter::ElementSet& filter_set) override
+    {
+        const BlockFilterIndex* block_filter_index{GetBlockFilterIndex(filter_type)};
+        if (!block_filter_index) return std::nullopt;
+
+        BlockFilter filter;
+        const CBlockIndex* index{WITH_LOCK(::cs_main, return chainman().m_blockman.LookupBlockIndex(block_hash))};
+        if (index == nullptr || !block_filter_index->LookupFilter(index, filter)) return std::nullopt;
+        return filter.GetFilter().MatchAny(filter_set);
+    }
     bool findBlock(const uint256& hash, const FoundBlock& block) override
     {
         WAIT_LOCK(cs_main, lock);