mixable transactions must be rct for v3

src/cryptonote_core/blockchain.cpp

@@ -2262,6 +2262,15 @@ bool Blockchain::check_tx_inputs(const transaction& tx, tx_verification_context
       if (txin.type() == typeid(txin_to_key))
       {
         const txin_to_key& in_to_key = boost::get<txin_to_key>(txin);
+        if (in_to_key.amount == 0)
+        {
+          // always consider rct inputs mixable. Even if there's not enough rct
+          // inputs on the chain to mix with, this is going to be the case for
+          // just a few blocks right after the fork at most
+          ++n_mixable;
+        }
+        else
+        {
           uint64_t n_outputs = m_db->get_num_outputs(in_to_key.amount);
           LOG_PRINT_L2("output size " << print_money(in_to_key.amount) << ": " << n_outputs << " available");
           // n_outputs includes the output we're considering
@@ -2269,10 +2278,23 @@ bool Blockchain::check_tx_inputs(const transaction& tx, tx_verification_context
             ++n_unmixable;
           else
             ++n_mixable;
+        }
         if (in_to_key.key_offsets.size() - 1 < mixin)
           mixin = in_to_key.key_offsets.size() - 1;
       }
     }
+
+    // for v3, we force txes with all mixable inputs to be rct
+    if (m_hardfork->get_current_version() >= 3)
+    {
+      if (n_unmixable == 0 && tx.version == 1)
+      {
+        LOG_PRINT_L1("Tx " << get_transaction_hash(tx) << " is not rct and does not have unmixable inputs");
+        tvc.m_not_rct = true;
+        return false;
+      }
+    }
+
     if (mixin < 2)
     {
       if (n_unmixable == 0)

src/cryptonote_core/verification_context.h

@@ -47,6 +47,7 @@ namespace cryptonote
     bool m_too_big;
     bool m_overspend;
     bool m_fee_too_low;
+    bool m_not_rct;
   };
 
   struct block_verification_context

src/rpc/core_rpc_server.cpp

@@ -483,6 +483,8 @@ namespace cryptonote
         res.reason = "overspend";
       if ((res.fee_too_low = tvc.m_fee_too_low))
         res.reason = "fee too low";
+      if ((res.not_rct = tvc.m_not_rct))
+        res.reason = "tx is not ringct";
       return true;
     }
 

src/rpc/core_rpc_server_commands_defs.h

@@ -376,6 +376,7 @@ namespace cryptonote
       bool too_big;
       bool overspend;
       bool fee_too_low;
+      bool not_rct;
 
       BEGIN_KV_SERIALIZE_MAP()
         KV_SERIALIZE(status)
@@ -388,6 +389,7 @@ namespace cryptonote
         KV_SERIALIZE(too_big)
         KV_SERIALIZE(overspend)
         KV_SERIALIZE(fee_too_low)
+        KV_SERIALIZE(not_rct)
       END_KV_SERIALIZE_MAP()
     };
   };