bcli: register --dev-max-fee-multiplier on our side

That way we pass the real min_acceptable (SLOW/2) and max_acceptable
(URGENT * 10) feerates to lightningd.

lightningd/bitcoind.c

@@ -153,8 +153,7 @@ static void bitcoin_plugin_send(struct bitcoind *bitcoind,
  *   - `htlc_resolution` is used for resolving onchain HTLCs
  *   - `penalty` is used for resolving revoked transactions
  *   - `min` is the minimum acceptable feerate
- *   - `max` is the maximum acceptable feerate, note that it will be multiplied by the
- *   config's  `max_fee_multiplier`.
+ *   - `max` is the maximum acceptable feerate
  *
  * Plugin response:
  * {

lightningd/chaintopology.c

@@ -870,12 +870,6 @@ u32 feerate_min(struct lightningd *ld, bool *unknown)
 	return min;
 }
 
-/* BOLT #2:
- *
- * Given the variance in fees, and the fact that the transaction may be
- * spent in the future, it's a good idea for the fee payer to keep a good
- * margin (say 5x the expected fee requirement)
- */
 u32 feerate_max(struct lightningd *ld, bool *unknown)
 {
 	u32 feerate;
@@ -900,7 +894,7 @@ u32 feerate_max(struct lightningd *ld, bool *unknown)
 		if (feehistory[i] > feerate)
 			feerate = feehistory[i];
 	}
-	return feerate * ld->config.max_fee_multiplier;
+	return feerate;
 }
 
 /* On shutdown, channels get deleted last.  That frees from our list, so

lightningd/lightningd.h

@@ -61,10 +61,6 @@ struct config {
 	/* ipv6 bind disable */
 	bool no_ipv6_bind;
 
-	/* Accept fee changes only if they are in the range our_fee -
-	 * our_fee*multiplier */
-	u32 max_fee_multiplier;
-
 	/* Are we allowed to use DNS lookup for peers. */
 	bool use_dns;
 

lightningd/options.c

@@ -518,13 +518,6 @@ static void dev_register_opts(struct lightningd *ld)
 	opt_register_arg("--dev-bitcoind-poll", opt_set_u32, opt_show_u32,
 			 &ld->topology->poll_seconds,
 			 "Time between polling for new transactions");
-	opt_register_arg("--dev-max-fee-multiplier", opt_set_u32, opt_show_u32,
-			 &ld->config.max_fee_multiplier,
-			 "Allow the fee proposed by the remote end to be up to "
-			 "multiplier times higher than our own. Small values "
-			 "will cause channels to be closed more often due to "
-			 "fee fluctuations, large values may result in large "
-			 "fees.");
 
 	opt_register_noarg("--dev-fast-gossip", opt_set_bool,
 			   &ld->dev_fast_gossip,
@@ -598,9 +591,6 @@ static const struct config testnet_config = {
 	/* Rescan 5 hours of blocks on testnet, it's reorg happy */
 	.rescan = 30,
 
-	/* Fees may be in the range our_fee - 10*our_fee */
-	.max_fee_multiplier = 10,
-
 	.use_dns = true,
 
 	/* Sets min_effective_htlc_capacity - at 1000$/BTC this is 10ct */
@@ -659,9 +649,6 @@ static const struct config mainnet_config = {
 	/* Rescan 2.5 hours of blocks on startup, it's not so reorg happy */
 	.rescan = 15,
 
-	/* Fees may be in the range our_fee - 10*our_fee */
-	.max_fee_multiplier = 10,
-
 	.use_dns = true,
 
 	/* Sets min_effective_htlc_capacity - at 1000$/BTC this is 10ct */

plugins/bcli.c

@@ -59,6 +59,10 @@ struct bitcoind {
 
 	/* Passthrough parameters for bitcoin-cli */
 	char *rpcuser, *rpcpass, *rpcconnect, *rpcport;
+
+	/* The factor to time the urgent feerate by to get the maximum
+	 * acceptable feerate. */
+	u32 max_fee_multiplier;
 };
 
 static struct bitcoind *bitcoind;
@@ -535,7 +539,14 @@ static struct command_result *estimatefees_final_step(struct bitcoin_cli *bcli)
 	/* We divide the slow feerate for the minimum acceptable, lightningd
 	 * will use floor if it's hit, though. */
 	json_add_u64(response, "min_acceptable", stash->slow / 2);
-	json_add_u64(response, "max_acceptable", stash->urgent);
+	/* BOLT #2:
+	*
+	* Given the variance in fees, and the fact that the transaction may be
+	* spent in the future, it's a good idea for the fee payer to keep a good
+	* margin (say 5x the expected fee requirement)
+	*/
+	json_add_u64(response, "max_acceptable",
+		     stash->urgent * bitcoind->max_fee_multiplier);
 
 	return command_finished(bcli->cmd, response);
 }
@@ -910,6 +921,7 @@ int main(int argc, char *argv[])
 	bitcoind->rpcpass = NULL;
 	bitcoind->rpcconnect = NULL;
 	bitcoind->rpcport = NULL;
+	bitcoind->max_fee_multiplier = 10;
 
 	plugin_main(argv, init, PLUGIN_STATIC, commands, ARRAY_SIZE(commands),
 		    NULL, 0, NULL, 0,
@@ -942,5 +954,15 @@ int main(int argc, char *argv[])
 				  "how long to keep retrying to contact bitcoind"
 				  " before fatally exiting",
 				  u64_option, &bitcoind->retry_timeout),
+#if DEVELOPER
+		    plugin_option("dev-max-fee-multiplier",
+				  "string",
+				  "Allow the fee proposed by the remote end to"
+				  " be up to multiplier times higher than our "
+				  "own. Small values will cause channels to be"
+				  " closed more often due to fee fluctuations,"
+				  " large values may result in large fees.",
+				  u32_option, &bitcoind->max_fee_multiplier),
+#endif /* DEVELOPER */
 		    NULL);
 }