blocksim: skip tx from and to coinbase

Squashed commit of the following:

commit 0de303f
Author: Chris Hager <[email protected]>
Date:   Mon Aug 16 21:54:34 2021 +0200

    blocksim: skip tx to coinbase

commit 0b9486a
Author: Chris Hager <[email protected]>
Date:   Mon Aug 16 21:52:27 2021 +0200

    check simblock tx from cb

Author: metachris

README.md

@@ -1,3 +1,7 @@
 Fork of [ethrpc](https://github.com/onrik/ethrpc) with Flashbots RPC calls.
 
 https://docs.flashbots.net/flashbots-auction/searchers/advanced/rpc-endpoint
+
+TODO:
+
+* Simulate block: account for outgoing transactions from coinbase (pool paying miners)

flashbotsrpc.go

@@ -611,6 +611,23 @@ func (rpc *FlashbotsRPC) FlashbotsSimulateBlock(privKey *ecdsa.PrivateKey, block
 	txs := make([]string, 0)
 	for _, tx := range block.Transactions() {
 		// fmt.Println("tx", i, tx.Hash(), "type", tx.Type())
+		from, fromErr := types.Sender(types.LatestSignerForChainID(tx.ChainId()), tx)
+		txIsFromCoinbase := fromErr == nil && from == block.Coinbase()
+		if txIsFromCoinbase {
+			if rpc.Debug {
+				fmt.Printf("- skip tx from coinbase: %s\n", tx.Hash())
+			}
+			continue
+		}
+
+		to := tx.To()
+		txIsToCoinbase := to != nil && *to == block.Coinbase()
+		if txIsToCoinbase {
+			if rpc.Debug {
+				fmt.Printf("- skip tx to coinbase: %s\n", tx.Hash())
+			}
+			continue
+		}
 
 		rlp := TxToRlp(tx)