reject poc requests txns if chainvar set

Author: andymck

include/blockchain_vars.hrl

@@ -173,6 +173,9 @@
 %% from POC targets :: boolean()
 -define(poc_activity_filter_enabled, poc_activity_filter_enabled).
 
+%% If set to true, all incoming poc request txns will be rejected : boolean
+-define(poc_reject_requests, poc_reject_requests).
+
 %% Number of blocks to wait before a hotspot can be eligible to participate in a poc
 %% challenge. This would avoid new hotspots getting challenged before they sync to an
 %% acceptable height.

src/transactions/v1/blockchain_txn_poc_request_v1.erl

@@ -154,6 +154,11 @@ is_valid(Txn, Chain) ->
     BaseTxn = Txn#blockchain_txn_poc_request_v1_pb{signature = <<>>},
     EncodedTxn = blockchain_txn_poc_request_v1_pb:encode_msg(BaseTxn),
 
+    %% if this var is enabled reject request txns
+    case blockchain:config(?poc_reject_requests, Ledger) of
+        {ok, true} -> throw({error, poc_requests_not_accepted});
+        _ -> ok
+    end,
     case blockchain_txn:validate_fields([{{secret_hash, ?MODULE:secret_hash(Txn)}, {binary, 32}},
                                          {{onion_key_hash, ?MODULE:secret_hash(Txn)}, {binary, 32}},
                                          {{block_hash, ?MODULE:secret_hash(Txn)}, {binary, 32}}]) of
@@ -274,7 +279,6 @@ maybe_log_duration(Type, Start) ->
         _ -> ok
     end.
 
-
 %% ------------------------------------------------------------------
 %% EUNIT Tests
 %% ------------------------------------------------------------------

src/transactions/v1/blockchain_txn_vars_v1.erl

@@ -1036,7 +1036,12 @@ validate_var(?poc_proposal_gc_window_check, Value) ->
         false -> ok;
         _ -> throw({error, {poc_proposal_gc_window_check, Value}})
     end;
-
+validate_var(?poc_reject_requests, Value) ->
+    case Value of
+        true -> ok;
+        false -> ok;
+        _ -> throw({error, {poc_reject_requests, Value}})
+    end;
 validate_var(?poc_challenge_sync_interval, Value) ->
     validate_int(Value, "poc_challenge_sync_interval", 10, 1440, false);
 validate_var(?poc_path_limit, undefined) ->