attempt 2 at fixing ban-on-tx-now-in-block

server.go

@@ -389,11 +389,13 @@ func (sp *serverPeer) addBanScore(persistent, transient uint32, reason string) b
 	}
 	score := sp.banScore.Increase(persistent, transient)
 	if score > warnThreshold {
-		peerLog.Warnf("Misbehaving peer %s: %s -- ban score increased to %d",
-			sp, reason, score)
+		peerLog.Warnf("Misbehaving peer %s: %s -- ban score increased to %d", sp, reason, score)
 		if score > cfg.BanThreshold {
-			peerLog.Warnf("Misbehaving peer %s -- banning and disconnecting",
-				sp)
+			if sp.server.ConnectedCount() <= 1 {
+				peerLog.Warnf("Refusing to ban peer %s as it is the only peer", sp)
+				return false
+			}
+			peerLog.Warnf("Misbehaving peer %s -- banning and disconnecting", sp)
 			sp.server.BanPeer(sp)
 			sp.Disconnect()
 			return true
@@ -1346,10 +1348,12 @@ func (sp *serverPeer) OnNotFound(p *peer.Peer, msg *wire.MsgNotFound) {
 		// This is an expected situation if transactions in the mempool make it into a block before
 		// this node knows about said block. We don't want to ban them for that alone
 		peerLog.Debugf("%d transactions not found on %s", numTxns, sp)
-		txStr := pickNoun(uint64(numTxns), "transaction", "transactions")
-		reason := fmt.Sprintf("%d %v not found on %s", numTxns, txStr, sp)
-		if sp.addBanScore(0, 25, reason) {
-			return // if they fail us four times in one minute, they're gone -- hitting them at new-block should be rare
+		if numBlocks+numTxns < wire.MaxInvPerMsg { // if our message is full then it is likely followed by another one that isn't
+			txStr := pickNoun(uint64(numTxns), "transaction", "transactions")
+			reason := fmt.Sprintf("%d %v not found on %s", numTxns, txStr, sp)
+			if sp.addBanScore(0, 20, reason) {
+				return // if they fail us five times in one minute, they're gone -- hitting them at new-block should be rare
+			}
 		}
 	}