Merge bitcoin/bitcoin#30598: assumeutxo: Drop block height from metadata

00618e8745192d209c23e3ae873c077e58168957 assumeutxo: Drop block height from metadata (Fabian Jahr)

Pull request description:

  Fixes https://github.com/bitcoin/bitcoin/issues/30514 which has more context and shows how the issue can be reproduced. Since the value in question is removed, there is no test to add to reproduce anything.

  This is an alternative approach to #30516 with much of the [code being suggested there](https://github.com/bitcoin/bitcoin/pull/30516#discussion_r1689146902).

ACKs for top commit:
  maflcko:
    re-ACK 00618e8745192d209c23e3ae873c077e58168957 🎌
  achow101:
    ACK 00618e8745192d209c23e3ae873c077e58168957
  theStack:
    Code-review ACK 00618e8745192d209c23e3ae873c077e58168957
  ismaelsadeeq:
    Re-ACK 00618e8745192d209c23e3ae873c077e58168957
  mzumsande:
    ACK 00618e8745192d209c23e3ae873c077e58168957

Tree-SHA512: db9575247bae838ad7742a27a216faaf55bb11e022f9afdd05752bb09bbf9614717d0ad64304ff5722a16bf41d8dea888af544e4ae26dcaa528c1add0269a4a8

1 files changed, 5 insertions, 8 deletions

diff --git a/src/node/utxo_snapshot.h b/src/node/utxo_snapshot.h
index a7c4135787..e4eb6d60ad 100644
--- a/src/node/utxo_snapshot.h
+++ b/src/node/utxo_snapshot.h
@@ -28,16 +28,17 @@ class Chainstate;
 namespace node {
 //! Metadata describing a serialized version of a UTXO set from which an
 //! assumeutxo Chainstate can be constructed.
+//! All metadata fields come from an untrusted file, so must be validated
+//! before being used. Thus, new fields should be added only if needed.
 class SnapshotMetadata
 {
-    const uint16_t m_version{1};
-    const std::set<uint16_t> m_supported_versions{1};
+    inline static const uint16_t VERSION{2};
+    const std::set<uint16_t> m_supported_versions{VERSION};
     const MessageStartChars m_network_magic;
 public:
     //! The hash of the block that reflects the tip of the chain for the
     //! UTXO set contained in this snapshot.
     uint256 m_base_blockhash;
-    uint32_t m_base_blockheight;
 
 
     //! The number of coins in the UTXO set contained in this snapshot. Used
@@ -50,19 +51,16 @@ public:
     SnapshotMetadata(
         const MessageStartChars network_magic,
         const uint256& base_blockhash,
-        const int base_blockheight,
         uint64_t coins_count) :
             m_network_magic(network_magic),
             m_base_blockhash(base_blockhash),
-            m_base_blockheight(base_blockheight),
             m_coins_count(coins_count) { }
 
     template <typename Stream>
     inline void Serialize(Stream& s) const {
         s << SNAPSHOT_MAGIC_BYTES;
-        s << m_version;
+        s << VERSION;
         s << m_network_magic;
-        s << m_base_blockheight;
         s << m_base_blockhash;
         s << m_coins_count;
     }
@@ -98,7 +96,6 @@ public:
             }
         }
 
-        s >> m_base_blockheight;
         s >> m_base_blockhash;
         s >> m_coins_count;
     }