lightningd: allow --commit-fee-max=0 for "no limit"

For testnet, fee estimates are not reliable at all.

Reported-by: Christian Decker
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

daemon/lightningd.c

@@ -117,7 +117,7 @@ static void config_register_opts(struct lightningd_state *dstate)
 			 "Minimum percentage of fee to accept for commitment");
 	opt_register_arg("--commit-fee-max=<percent>", opt_set_u32, opt_show_u32,
 			 &dstate->config.commitment_fee_max_percent,
-			 "Maximum percentage of fee to accept for commitment");
+			 "Maximum percentage of fee to accept for commitment (0 for unlimited)");
 	opt_register_arg("--commit-fee=<percent>", opt_set_u32, opt_show_u32,
 			 &dstate->config.commitment_fee_percent,
 			 "Percentage of fee to request for their commitment");
@@ -226,7 +226,8 @@ static void default_config(struct config *config)
 static void check_config(struct lightningd_state *dstate)
 {
 	/* We do this by ensuring it's less than the minimum we would accept. */
-	if (dstate->config.commitment_fee_max_percent
+	if (dstate->config.commitment_fee_max_percent != 0
+	    && dstate->config.commitment_fee_max_percent
 	    < dstate->config.commitment_fee_min_percent)
 		fatal("Commitment fee invalid min-max %u-%u",
 		      dstate->config.commitment_fee_min_percent,

daemon/packets.c

@@ -308,8 +308,9 @@ Pkt *accept_pkt_open(struct peer *peer, const Pkt *pkt,
 		return pkt_err(peer, "Commitment fee %u below %"PRIu64" x %u%%",
 			       o->initial_fee_rate, feerate,
 			       peer->dstate->config.commitment_fee_min_percent);
-	if (o->initial_fee_rate
+	if (peer->dstate->config.commitment_fee_max_percent != 0
-	    > feerate * peer->dstate->config.commitment_fee_max_percent / 100)
+	    && (o->initial_fee_rate
+		> feerate * peer->dstate->config.commitment_fee_max_percent/100))
 		return pkt_err(peer, "Commitment fee %u above %"PRIu64" x %u%%",
 			       o->initial_fee_rate, feerate,
 			       peer->dstate->config.commitment_fee_max_percent);