Add a grace period to deregistrations after a hardfork

It is not uncommon to have nodes get decommissioned after a hardfork,
either due to lack of updating or issues with the release. This
implements a 7 day grace period where nodes that do get decommissioned
will not progress into a deregistration (and being hit with the 30 day
funds locked penalty).

src/cryptonote_basic/hardfork.cpp

@@ -117,7 +117,6 @@ std::pair<const hard_fork*, const hard_fork*> get_hard_forks(network_type type)
   return {nullptr, nullptr};
 }
 
-
 std::pair<std::optional<uint64_t>, std::optional<uint64_t>>
 get_hard_fork_heights(network_type nettype, hf version) {
   std::pair<std::optional<uint64_t>, std::optional<uint64_t>> found;

src/cryptonote_config.h

@@ -321,6 +321,8 @@ namespace config
     "LDBEN6Ut4NkMwyaXWZ7kBEAx8X64o6YtDhLXUP26uLHyYT4nFmcaPU2Z2fauqrhTLh4Qfr61pUUZVLaTHqAdycETKM1STrz"sv, // hardfork v11
   };
 
+  inline constexpr uint64_t HARDFORK_DEREGISTRATION_GRACE_PERIOD = 7 * cryptonote::BLOCKS_PER_DAY; // After a hardfork we will decommission sns but wont dereg, allowing time to update
+
   inline constexpr auto UPTIME_PROOF_TOLERANCE = 5min; // How much an uptime proof timestamp can deviate from our timestamp before we refuse it
   inline constexpr auto UPTIME_PROOF_STARTUP_DELAY = 30s; // How long to wait after startup before broadcasting a proof
   inline constexpr auto UPTIME_PROOF_CHECK_INTERVAL = 30s; // How frequently to check whether we need to broadcast a proof
@@ -432,6 +434,8 @@ struct network_config
   uint64_t LIMIT_BATCH_OUTPUTS;
   uint64_t SERVICE_NODE_PAYABLE_AFTER_BLOCKS;
 
+  uint64_t HARDFORK_DEREGISTRATION_GRACE_PERIOD;
+
 
   inline constexpr std::string_view governance_wallet_address(hf hard_fork_version) const {
     const auto wallet_switch =
@@ -466,6 +470,7 @@ inline constexpr network_config mainnet_config{
   config::MIN_BATCH_PAYMENT_AMOUNT,
   config::LIMIT_BATCH_OUTPUTS,
   config::SERVICE_NODE_PAYABLE_AFTER_BLOCKS,
+  config::HARDFORK_DEREGISTRATION_GRACE_PERIOD,
 };
 inline constexpr network_config testnet_config{
   network_type::TESTNET,
@@ -492,6 +497,7 @@ inline constexpr network_config testnet_config{
   config::MIN_BATCH_PAYMENT_AMOUNT,
   config::LIMIT_BATCH_OUTPUTS,
   config::testnet::SERVICE_NODE_PAYABLE_AFTER_BLOCKS,
+  config::HARDFORK_DEREGISTRATION_GRACE_PERIOD,
 };
 inline constexpr network_config devnet_config{
   network_type::DEVNET,
@@ -518,6 +524,7 @@ inline constexpr network_config devnet_config{
   config::MIN_BATCH_PAYMENT_AMOUNT,
   config::LIMIT_BATCH_OUTPUTS,
   config::testnet::SERVICE_NODE_PAYABLE_AFTER_BLOCKS,
+  config::HARDFORK_DEREGISTRATION_GRACE_PERIOD,
 };
 inline constexpr network_config fakenet_config{
   network_type::FAKECHAIN,
@@ -544,6 +551,7 @@ inline constexpr network_config fakenet_config{
   config::MIN_BATCH_PAYMENT_AMOUNT,
   config::LIMIT_BATCH_OUTPUTS,
   config::testnet::SERVICE_NODE_PAYABLE_AFTER_BLOCKS,
+  config::HARDFORK_DEREGISTRATION_GRACE_PERIOD,
 };
 
 inline constexpr const network_config& get_config(network_type nettype)

src/cryptonote_core/service_node_quorum_cop.cpp

@@ -403,6 +403,13 @@ namespace service_nodes
                   }
                 }
 
+                if (vote_for_state == new_state::deregister && height - *cryptonote::get_hard_fork_heights(m_core.get_nettype(), hf_version).first < netconf.HARDFORK_DEREGISTRATION_GRACE_PERIOD) {
+                  LOG_PRINT_L2("Decommissioned service node "
+                               << quorum->workers[node_index]
+                               << " is still not passing required checks, and has no remaining credits left. However it is within the grace period of a hardfork so has not been deregistered.");
+                  continue;
+                }
+
                 quorum_vote_t vote = service_nodes::make_state_change_vote(m_obligations_height, static_cast<uint16_t>(index_in_group), node_index, vote_for_state, reason, my_keys);
                 cryptonote::vote_verification_context vvc;
                 if (!handle_vote(vote, vvc))