merge bitcoin#24832: Verify the block filter hash when reading the filter from disk

Author: kwvg

src/bench/gcs_filter.cpp

@@ -5,38 +5,84 @@
 #include <bench/bench.h>
 #include <blockfilter.h>
 
-static void ConstructGCSFilter(benchmark::Bench& bench)
+static const GCSFilter::ElementSet GenerateGCSTestElements()
 {
     GCSFilter::ElementSet elements;
-    for (int i = 0; i < 10000; ++i) {
+
+    // Testing the benchmarks with different number of elements show that a filter
+    // with at least 100,000 elements results in benchmarks that have the same
+    // ns/op. This makes it easy to reason about how long (in nanoseconds) a single
+    // filter element takes to process.
+    for (int i = 0; i < 100000; ++i) {
         GCSFilter::Element element(32);
         element[0] = static_cast<unsigned char>(i);
         element[1] = static_cast<unsigned char>(i >> 8);
         elements.insert(std::move(element));
     }
 
+    return elements;
+}
+
+static void GCSBlockFilterGetHash(benchmark::Bench& bench)
+{
+    auto elements = GenerateGCSTestElements();
+
+    GCSFilter filter({0, 0, BASIC_FILTER_P, BASIC_FILTER_M}, elements);
+    BlockFilter block_filter(BlockFilterType::BASIC_FILTER, {}, filter.GetEncoded(), /*skip_decode_check=*/false);
+
+    bench.run([&] {
+        block_filter.GetHash();
+    });
+}
+
+static void GCSFilterConstruct(benchmark::Bench& bench)
+{
+    auto elements = GenerateGCSTestElements();
+
     uint64_t siphash_k0 = 0;
-    bench.batch(elements.size()).unit("elem").run([&] {
-        GCSFilter filter({siphash_k0, 0, 20, 1 << 20}, elements);
+    bench.run([&]{
+        GCSFilter filter({siphash_k0, 0, BASIC_FILTER_P, BASIC_FILTER_M}, elements);
+
         siphash_k0++;
     });
 }
 
-static void MatchGCSFilter(benchmark::Bench& bench)
+static void GCSFilterDecode(benchmark::Bench& bench)
 {
-    GCSFilter::ElementSet elements;
-    for (int i = 0; i < 10000; ++i) {
-        GCSFilter::Element element(32);
-        element[0] = static_cast<unsigned char>(i);
-        element[1] = static_cast<unsigned char>(i >> 8);
-        elements.insert(std::move(element));
-    }
-    GCSFilter filter({0, 0, 20, 1 << 20}, elements);
+    auto elements = GenerateGCSTestElements();
 
-    bench.unit("elem").run([&] {
-        filter.Match(GCSFilter::Element());
+    GCSFilter filter({0, 0, BASIC_FILTER_P, BASIC_FILTER_M}, elements);
+    auto encoded = filter.GetEncoded();
+
+    bench.run([&] {
+        GCSFilter filter({0, 0, BASIC_FILTER_P, BASIC_FILTER_M}, encoded, /*skip_decode_check=*/false);
+    });
+}
+
+static void GCSFilterDecodeSkipCheck(benchmark::Bench& bench)
+{
+    auto elements = GenerateGCSTestElements();
+
+    GCSFilter filter({0, 0, BASIC_FILTER_P, BASIC_FILTER_M}, elements);
+    auto encoded = filter.GetEncoded();
+
+    bench.run([&] {
+        GCSFilter filter({0, 0, BASIC_FILTER_P, BASIC_FILTER_M}, encoded, /*skip_decode_check=*/true);
     });
 }
 
-BENCHMARK(ConstructGCSFilter);
-BENCHMARK(MatchGCSFilter);
+static void GCSFilterMatch(benchmark::Bench& bench)
+{
+    auto elements = GenerateGCSTestElements();
+
+    GCSFilter filter({0, 0, BASIC_FILTER_P, BASIC_FILTER_M}, elements);
+
+    bench.run([&] {
+        filter.Match(GCSFilter::Element());
+    });
+}
+BENCHMARK(GCSBlockFilterGetHash);
+BENCHMARK(GCSFilterConstruct);
+BENCHMARK(GCSFilterDecode);
+BENCHMARK(GCSFilterDecodeSkipCheck);
+BENCHMARK(GCSFilterMatch);

src/blockfilter.cpp

@@ -47,7 +47,7 @@ GCSFilter::GCSFilter(const Params& params)
     : m_params(params), m_N(0), m_F(0), m_encoded{0}
 {}
 
-GCSFilter::GCSFilter(const Params& params, std::vector<unsigned char> encoded_filter)
+GCSFilter::GCSFilter(const Params& params, std::vector<unsigned char> encoded_filter, bool skip_decode_check)
     : m_params(params), m_encoded(std::move(encoded_filter))
 {
     SpanReader stream{GCS_SER_TYPE, GCS_SER_VERSION, m_encoded, 0};
@@ -59,6 +59,8 @@ GCSFilter::GCSFilter(const Params& params, std::vector<unsigned char> encoded_fi
     }
     m_F = static_cast<uint64_t>(m_N) * static_cast<uint64_t>(m_params.m_M);
 
+    if (skip_decode_check) return;
+
     // Verify that the encoded filter contains exactly N elements. If it has too much or too little
     // data, a std::ios_base::failure exception will be raised.
     BitStreamReader<SpanReader> bitreader{stream};
@@ -219,14 +221,14 @@ static GCSFilter::ElementSet BasicFilterElements(const CBlock& block,
 }
 
 BlockFilter::BlockFilter(BlockFilterType filter_type, const uint256& block_hash,
-                         std::vector<unsigned char> filter)
+                         std::vector<unsigned char> filter, bool skip_decode_check)
     : m_filter_type(filter_type), m_block_hash(block_hash)
 {
     GCSFilter::Params params;
     if (!BuildParams(params)) {
         throw std::invalid_argument("unknown filter_type");
     }
-    m_filter = GCSFilter(params, std::move(filter));
+    m_filter = GCSFilter(params, std::move(filter), skip_decode_check);
 }
 
 BlockFilter::BlockFilter(BlockFilterType filter_type, const CBlock& block, const CBlockUndo& block_undo)

src/blockfilter.h

@@ -60,7 +60,7 @@ class GCSFilter
     explicit GCSFilter(const Params& params = Params());
 
     /** Reconstructs an already-created filter from an encoding. */
-    GCSFilter(const Params& params, std::vector<unsigned char> encoded_filter);
+    GCSFilter(const Params& params, std::vector<unsigned char> encoded_filter, bool skip_decode_check);
 
     /** Builds a new filter from the params and set of elements. */
     GCSFilter(const Params& params, const ElementSet& elements);
@@ -123,7 +123,7 @@ class BlockFilter
 
     //! Reconstruct a BlockFilter from parts.
     BlockFilter(BlockFilterType filter_type, const uint256& block_hash,
-                std::vector<unsigned char> filter);
+                std::vector<unsigned char> filter, bool skip_decode_check);
 
     //! Construct a new BlockFilter of the specified type from a block.
     BlockFilter(BlockFilterType filter_type, const CBlock& block, const CBlockUndo& block_undo);
@@ -165,7 +165,7 @@ class BlockFilter
         if (!BuildParams(params)) {
             throw std::ios_base::failure("unknown filter_type");
         }
-        m_filter = GCSFilter(params, std::move(encoded_filter));
+        m_filter = GCSFilter(params, std::move(encoded_filter), /*skip_decode_check=*/false);
     }
 };
 

src/index/blockfilterindex.cpp

@@ -5,6 +5,7 @@
 #include <map>
 
 #include <dbwrapper.h>
+#include <hash.h>
 #include <index/blockfilterindex.h>
 #include <node/blockstorage.h>
 #include <serialize.h>
@@ -146,18 +147,22 @@ bool BlockFilterIndex::CommitInternal(CDBBatch& batch)
     return BaseIndex::CommitInternal(batch);
 }
 
-bool BlockFilterIndex::ReadFilterFromDisk(const FlatFilePos& pos, BlockFilter& filter) const
+bool BlockFilterIndex::ReadFilterFromDisk(const FlatFilePos& pos, const uint256& hash, BlockFilter& filter) const
 {
     CAutoFile filein(m_filter_fileseq->Open(pos, true), SER_DISK, CLIENT_VERSION);
     if (filein.IsNull()) {
         return false;
     }
 
+    // Check that the hash of the encoded_filter matches the one stored in the db.
     uint256 block_hash;
     std::vector<uint8_t> encoded_filter;
     try {
         filein >> block_hash >> encoded_filter;
-        filter = BlockFilter(GetFilterType(), block_hash, std::move(encoded_filter));
+        uint256 result;
+        CHash256().Write(encoded_filter).Finalize(result);
+        if (result != hash) return error("Checksum mismatch in filter decode.");
+        filter = BlockFilter(GetFilterType(), block_hash, std::move(encoded_filter), /*skip_decode_check=*/true);
     }
     catch (const std::exception& e) {
         return error("%s: Failed to deserialize block filter from disk: %s", __func__, e.what());
@@ -384,7 +389,7 @@ bool BlockFilterIndex::LookupFilter(const CBlockIndex* block_index, BlockFilter&
         return false;
     }
 
-    return ReadFilterFromDisk(entry.pos, filter_out);
+    return ReadFilterFromDisk(entry.pos, entry.hash, filter_out);
 }
 
 bool BlockFilterIndex::LookupFilterHeader(const CBlockIndex* block_index, uint256& header_out)
@@ -428,7 +433,7 @@ bool BlockFilterIndex::LookupFilterRange(int start_height, const CBlockIndex* st
     filters_out.resize(entries.size());
     auto filter_pos_it = filters_out.begin();
     for (const auto& entry : entries) {
-        if (!ReadFilterFromDisk(entry.pos, *filter_pos_it)) {
+        if (!ReadFilterFromDisk(entry.pos, entry.hash, *filter_pos_it)) {
             return false;
         }
         ++filter_pos_it;

src/index/blockfilterindex.h

@@ -32,7 +32,7 @@ class BlockFilterIndex final : public BaseIndex
     FlatFilePos m_next_filter_pos;
     std::unique_ptr<FlatFileSeq> m_filter_fileseq;
 
-    bool ReadFilterFromDisk(const FlatFilePos& pos, BlockFilter& filter) const;
+    bool ReadFilterFromDisk(const FlatFilePos& pos, const uint256& hash, BlockFilter& filter) const;
     size_t WriteFilterToDisk(FlatFilePos& pos, const BlockFilter& filter);
 
     Mutex m_cs_headers_cache;