Activate new protocol with fork.

This defines a new time-activated "fork", Fork::CustomRewardAddresses.
For now, it is scheduled at timestamp 2000000000; that will be set to
the actual activation time once it is determined.

When this fork becomes active (i.e. the current best block's timestamp
goes beyond the activation time), we require peers to use the new protocol
version that supports custom reward addresses.  The fork has no other
(in particular, no consensus-level) consequences.

Author: domob1812

divi/src/ForkActivation.cpp

@@ -27,6 +27,8 @@ const std::unordered_map<Fork, int64_t,std::hash<int>> ACTIVATION_TIMES = {
   {Fork::UniformLotteryWinners, unixTimestampForDec31stMidnight},
   /* FIXME: Schedule for a real time.  */
   {Fork::CheckLockTimeVerify, 2000000000},
+  /** FIXME: Set actual time once scheduled.  */
+  {Fork::CustomRewardAddresses, 2000000000},
 };
 
 } // anonymous namespace

divi/src/ForkActivation.h

@@ -23,6 +23,13 @@ enum Fork
   HardenedStakeModifier,
   UniformLotteryWinners,
   CheckLockTimeVerify,
+
+  /**
+   * Custom reward addresses for masternodes.  This is activated like other
+   * forks based on block time; but it only affects the network protocol
+   * we require from peers, not the actual consensus logic.
+   */
+  CustomRewardAddresses,
 };
 
 /**

divi/src/main.cpp

@@ -21,6 +21,7 @@
 #include "coins.h"
 #include <defaultValues.h>
 #include "FeeRate.h"
+#include "ForkActivation.h"
 #include "init.h"
 #include "kernel.h"
 #include "libzerocoin/bignum.h"

divi/src/version.cpp

@@ -1,21 +1,29 @@
 #include <version.h>
 
+#include <chain.h>
 #include <chainparams.h>
+#include <ForkActivation.h>
 #include <Settings.h>
 
+extern CChain chainActive;
 extern Settings& settings;
 
-// Note: whenever a protocol update is needed toggle between both implementations (comment out the formerly active one)
-//       so we can leave the existing clients untouched (old SPORK will stay on so they don't see even older clients).
-//       Those old clients won't react to the changes of the other (new) SPORK because at the time of their implementation
-//       it was the one which was commented out
 int ActiveProtocol()
 {
     if (settings.ParameterIsSet("-activeversion"))
         return settings.GetArg("-activeversion", 0);
 
+    /* On regtest, we set the new protocol as active without any further
+       ado.  This allows proper testing of the changed logic.  */
     if (Params().NetworkID() == CBaseChainParams::REGTEST)
         return MN_REWARD_SCRIPT_VERSION;
 
+    /* Otherwise, the protocol update is tied to time-based activation of
+       a network fork (which in fact does not fork consensus but just the
+       network protocol).  */
+    const CBlockIndex* tip = chainActive.Tip();
+    if (tip != nullptr && ActivationState(tip).IsActive(Fork::CustomRewardAddresses))
+        return MN_REWARD_SCRIPT_VERSION;
+
     return MIN_PEER_PROTO_VERSION_AFTER_ENFORCEMENT;
 }