From a4afb9cadbaecb0676e6475ab8d32a52faecb47a Mon Sep 17 00:00:00 2001
From: Jim Posen <jimpo@coinbase.com>
Date: Tue, 23 Jan 2018 17:32:46 -0800
Subject: blockfilter: Additional helper methods to compute hash and header.

---
 src/blockfilter.cpp | 21 +++++++++++++++++++++
 src/blockfilter.h   |  6 ++++++
 2 files changed, 27 insertions(+)

diff --git a/src/blockfilter.cpp b/src/blockfilter.cpp
index 1119b54901..124cbcfd92 100644
--- a/src/blockfilter.cpp
+++ b/src/blockfilter.cpp
@@ -233,3 +233,24 @@ BlockFilter::BlockFilter(BlockFilterType filter_type, const CBlock& block, const
         throw std::invalid_argument("unknown filter_type");
     }
 }
+
+uint256 BlockFilter::GetHash() const
+{
+    const std::vector<unsigned char>& data = GetEncodedFilter();
+
+    uint256 result;
+    CHash256().Write(data.data(), data.size()).Finalize(result.begin());
+    return result;
+}
+
+uint256 BlockFilter::ComputeHeader(const uint256& prev_header) const
+{
+    const uint256& filter_hash = GetHash();
+
+    uint256 result;
+    CHash256()
+        .Write(filter_hash.begin(), filter_hash.size())
+        .Write(prev_header.begin(), prev_header.size())
+        .Finalize(result.begin());
+    return result;
+}
diff --git a/src/blockfilter.h b/src/blockfilter.h
index 010f868aee..46833ac0be 100644
--- a/src/blockfilter.h
+++ b/src/blockfilter.h
@@ -106,6 +106,12 @@ public:
         return m_filter.GetEncoded();
     }
 
+    // Compute the filter hash.
+    uint256 GetHash() const;
+
+    // Compute the filter header given the previous one.
+    uint256 ComputeHeader(const uint256& prev_header) const;
+
     template <typename Stream>
     void Serialize(Stream& s) const {
         s << m_block_hash
-- 
cgit v1.2.3