Merge b739240 into 27caa32

include/bitcoin/bitcoin/machine/rule_fork.hpp

@@ -70,6 +70,9 @@ enum rule_fork : uint32_t
     /// Prevent dummy value malleability (soft fork, feature).
     bip147_rule = 1u << 13,
 
+    /// Fix Satoshi's time warp bug (hard fork, feature).
+    time_warp_patch = 1u << 14,
+
     // TODO: future bitcoin forks work forward from << 14.
     // TODO: splitcoin/altcoin forks work backwards from << 30.
     ////time_warp_patch = 1u << 29,

src/chain/chain_state.cpp

@@ -21,6 +21,7 @@
 #include <algorithm>
 #include <cstddef>
 #include <cstdint>
+#include <iterator>
 #include <boost/range/adaptor/reversed.hpp>
 #include <bitcoin/bitcoin/chain/block.hpp>
 #include <bitcoin/bitcoin/chain/chain_state.hpp>
@@ -86,6 +87,8 @@ chain_state::activations chain_state::activation(const data& values,
     const auto difficult = script::is_enabled(forks, rule_fork::difficult);
     const auto retarget = script::is_enabled(forks, rule_fork::retarget);
     const auto mainnet = retarget && difficult;
+    const auto time_warp = script::is_enabled(forks, rule_fork::time_warp_patch
+        );
 
     //*************************************************************************
     // CONSENSUS: Though unspecified in bip34, the satoshi implementation
@@ -191,6 +194,9 @@ chain_state::activations chain_state::activation(const data& values,
         result.minimum_block_version = settings.first_version;
     }
 
+    if (time_warp)
+        result.forks |= (rule_fork::time_warp_patch & forks);
+
     // TODO: add configurable option to apply transaction version policy.
     result.maximum_transaction_version = max_uint32;
     return result;
@@ -481,8 +487,10 @@ chain_state::data chain_state::to_pool(const chain_state& top,
     // Alias configured forks.
     const auto forks = top.forks_;
 
-    // Retargeting is only activated via configuration.
+    // Retargeting and time_warp_patch are only activated via configuration.
     const auto retarget = script::is_enabled(forks, rule_fork::retarget);
+    const auto time_warp = script::is_enabled(forks, rule_fork::time_warp_patch
+        );
 
     // Copy data from presumed previous-height block state.
     auto data = top.data_;
@@ -513,7 +521,8 @@ chain_state::data chain_state::to_pool(const chain_state& top,
     // If promoting from retarget height, move that timestamp into retarget.
     if (retarget &&
         is_retarget_height(height - 1u, settings.retargeting_interval))
-        data.timestamp.retarget = data.timestamp.self;
+        data.timestamp.retarget = (time_warp && height != 1) ?
+            *std::next(data.timestamp.ordered.crbegin()) : data.timestamp.self;
 
     // Replace previous block state with tx pool chain state for next height
     // Preserve top block timestamp for use in computation of staleness.