Implement ONLY_BILL_FIRST_AUTHORIZER protocol feature

libraries/chain/controller.cpp

@@ -1088,7 +1088,13 @@ struct controller_impl {
          trx_context.init_for_deferred_trx( gtrx.published );
 
          if( trx_context.enforce_whiteblacklist && pending->_block_status == controller::block_status::incomplete ) {
-            check_actor_list( trx_context.bill_to_accounts ); // Assumes bill_to_accounts is the set of actors authorizing the transaction
+            flat_set<account_name> actors;
+            for( const auto& act : trx_context.trx.actions ) {
+               for( const auto& auth : act.authorization ) {
+                  actors.insert( auth.actor );
+               }
+            }
+            check_actor_list( actors );
          }
 
          trx_context.exec();

libraries/chain/include/eosio/chain/protocol_feature_manager.hpp

@@ -19,7 +19,8 @@ enum class builtin_protocol_feature_t : uint32_t {
    replace_deferred,
    fix_linkauth_restriction,
    disallow_empty_producer_schedule,
-   restrict_action_to_self
+   restrict_action_to_self,
+   only_bill_first_authorizer
 };
 
 struct protocol_feature_subjective_restrictions {

libraries/chain/include/eosio/chain/transaction.hpp

@@ -66,7 +66,8 @@ namespace eosio { namespace chain {
                                                      bool allow_duplicate_keys = false) const;
 
       uint32_t total_actions()const { return context_free_actions.size() + actions.size(); }
-      account_name first_authorizor()const {
+
+      account_name first_authorizer()const {
          for( const auto& a : actions ) {
             for( const auto& u : a.authorization )
                return u.actor;

libraries/chain/protocol_feature_manager.cpp

@@ -86,6 +86,17 @@ Builtin protocol feature: RESTRICT_ACTION_TO_SELF
 Disallows bypass of authorization checks by unprivileged contracts when sending inline actions or deferred transactions.
 The original protocol rules allow a bypass of authorization checks for actions sent by a contract to itself.
 This protocol feature removes that bypass.
+*/
+            {}
+         } )
+         (  builtin_protocol_feature_t::only_bill_first_authorizer, builtin_protocol_feature_spec{
+            "ONLY_BILL_FIRST_AUTHORIZER",
+            fc::variant("2f1f13e291c79da5a2bbad259ed7c1f2d34f697ea460b14b565ac33b063b73e2").as<digest_type>(),
+            // SHA256 hash of the raw message below within the comment delimiters (do not modify message below).
+/*
+Builtin protocol feature: ONLY_BILL_FIRST_AUTHORIZER
+
+Adds CPU and network bandwidth usage to only the first authorizer of a transaction.
 */
             {}
          } )

libraries/chain/transaction_context.cpp

@@ -218,9 +218,13 @@ namespace bacc = boost::accumulators;
          validate_cpu_usage_to_bill( billed_cpu_time_us, false ); // Fail early if the amount to be billed is too high
 
       // Record accounts to be billed for network and CPU usage
-      for( const auto& act : trx.actions ) {
-         for( const auto& auth : act.authorization ) {
-            bill_to_accounts.insert( auth.actor );
+      if( control.is_builtin_activated(builtin_protocol_feature_t::only_bill_first_authorizer) ) {
+         bill_to_accounts.insert( trx.first_authorizer() );
+      } else {
+         for( const auto& act : trx.actions ) {
+            for( const auto& auth : act.authorization ) {
+               bill_to_accounts.insert( auth.actor );
+            }
          }
       }
       validate_ram_usage.reserve( bill_to_accounts.size() );
@@ -583,7 +587,7 @@ namespace bacc = boost::accumulators;
                          + static_cast<uint64_t>(config::transaction_id_net_usage) ); // Will exit early if net usage cannot be payed.
       }
 
-      auto first_auth = trx.first_authorizor();
+      auto first_auth = trx.first_authorizer();
 
       uint32_t trx_size = 0;
       const auto& cgto = control.mutable_db().create<generated_transaction_object>( [&]( auto& gto ) {

unittests/auth_tests.cpp

@@ -371,7 +371,8 @@ BOOST_AUTO_TEST_CASE( any_auth ) { try {
 
 BOOST_AUTO_TEST_CASE(no_double_billing) {
 try {
-   TESTER chain;
+   validating_tester chain( validating_tester::default_config() );
+   chain.execute_setup_policy( setup_policy::preactivate_feature_and_new_bios );
 
    chain.produce_block();
 
@@ -490,7 +491,7 @@ BOOST_AUTO_TEST_CASE( linkauth_special ) { try {
    chain.create_account(N(tester));
    chain.create_account(N(tester2));
    chain.produce_blocks();
-   
+
    chain.push_action(config::system_account_name, updateauth::get_name(), tester_account, fc::mutable_variant_object()
            ("account", "tester")
            ("permission", "first")