lightningd: remove --deadline-blocks option.

We will derive it from other factors.

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

lightningd/lightningd.h

@@ -55,9 +55,6 @@ struct config {
 	/* Maximum time for an expiring HTLC (blocks). */
 	u32 max_htlc_expiry;
 
-	/* How many blocks before upstream HTLC expiry do we panic and dump? */
-	u32 deadline_blocks;
-
 	/* Fee rates. */
 	u32 fee_base;
 	s32 fee_per_satoshi;

lightningd/options.c

@@ -238,9 +238,6 @@ static void config_register_opts(struct lightningd *ld)
 	opt_register_arg("--max-htlc-expiry", opt_set_u32, opt_show_u32,
 			 &ld->config.max_htlc_expiry,
 			 "Maximum number of blocks to accept an HTLC before expiry");
-	opt_register_arg("--deadline-blocks", opt_set_u32, opt_show_u32,
-			 &ld->config.deadline_blocks,
-			 "Number of blocks before HTLC timeout before we drop connection");
 	opt_register_arg("--bitcoind-poll", opt_set_time, opt_show_time,
 			 &ld->config.poll_time,
 			 "Time between polling for new transactions");
@@ -338,9 +335,6 @@ static const struct config testnet_config = {
 	/* Don't lock up channel for more than 5 days. */
 	.max_htlc_expiry = 5 * 6 * 24,
 
-	/* If we're closing on HTLC expiry, and you're unresponsive, we abort. */
-	.deadline_blocks = 4,
-
 	/* How often to bother bitcoind. */
 	.poll_time = TIME_FROM_SEC(10),
 
@@ -406,9 +400,6 @@ static const struct config mainnet_config = {
 	/* Don't lock up channel for more than 5 days. */
 	.max_htlc_expiry = 5 * 6 * 24,
 
-	/* If we're closing on HTLC expiry, and you're unresponsive, we abort. */
-	.deadline_blocks = 10,
-
 	/* How often to bother bitcoind. */
 	.poll_time = TIME_FROM_SEC(30),
 
@@ -441,17 +432,6 @@ static void check_config(struct lightningd *ld)
 
 	if (ld->config.anchor_confirms == 0)
 		fatal("anchor-confirms must be greater than zero");
-
-	/* FIXME-OLD #2:
-	 *
-	 * a node MUST estimate the deadline for successful redemption
-	 * for each HTLC it offers.  A node MUST NOT offer a HTLC
-	 * after this deadline */
-	if (ld->config.deadline_blocks >= ld->config.cltv_final
-	    || ld->config.deadline_blocks >= ld->config.cltv_expiry_delta)
-		fatal("Deadline %u can't be more than final/expiry %u/%u",
-		      ld->config.deadline_blocks,
-		      ld->config.cltv_final, ld->config.cltv_expiry_delta);
 }
 
 static void setup_default_config(struct lightningd *ld)

lightningd/peer_htlcs.c

@@ -527,22 +527,19 @@ static void forward_htlc(struct htlc_in *hin,
 		goto fail;
 	}
 
-	/* BOLT #4:
+	/* BOLT #2:
 	 *
-	 * If the `cltv_expiry` is too near, we tell them the the current channel
-	 * setting for the outgoing channel:
-	 * 1. type: UPDATE|14 (`expiry_too_soon`)
-	 * 2. data:
-	 *    * [`2`:`len`]
-	 *    * [`len`:`channel_update`]
+	 * A node MUST estimate a timeout deadline for each HTLC it offers.  A
+	 * node MUST NOT offer an HTLC with a timeout deadline before its
+	 * `cltv_expiry`
 	 */
-	if (get_block_height(next->ld->topology)
-	    + next->ld->config.deadline_blocks >= outgoing_cltv_value) {
+	/* In our case, G = 1, so we need to expire it one after it's expiration.
+	 * But never offer an expired HTLC; that's dumb. */
+	if (get_block_height(next->ld->topology) >= outgoing_cltv_value) {
 		log_debug(hin->key.peer->log,
-			  "Expiry cltv %u too close to current %u + deadline %u",
+			  "Expiry cltv %u too close to current %u",
 			  outgoing_cltv_value,
-			  get_block_height(next->ld->topology),
-			  next->ld->config.deadline_blocks);
+			  get_block_height(next->ld->topology));
 		failcode = WIRE_EXPIRY_TOO_SOON;
 		goto fail;
 	}

tests/utils.py

@@ -20,7 +20,6 @@ BITCOIND_CONFIG = {
 LIGHTNINGD_CONFIG = {
     "bitcoind-poll": "1s",
     "log-level": "debug",
-    "deadline-blocks": 4,
     "cltv-delta": 6,
     "cltv-final": 5,
     "locktime-blocks": 5,