options: be more conservative with timeouts on mainnet.

As per https://github.com/lightningnetwork/lightning-rfc/pull/785

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Changelog-Changed: config: the default CLTV expiry is now 34 blocks, and final expiry 18 blocks as per new BOLT recommendations.

Makefile

@@ -24,7 +24,7 @@ CCANDIR := ccan
 
 # Where we keep the BOLT RFCs
 BOLTDIR := ../lightning-rfc/
-BOLTVERSION := c053ce7afb4cbf88615877a0d5fc7b8dbe2b9ba0
+BOLTVERSION := 886bf7a430db706b483b7b02d64a82bf175c0b46
 
 -include config.vars
 

lightningd/options.c

@@ -639,16 +639,16 @@ static const struct config mainnet_config = {
 	/* BOLT #2:
 	 *
 	 * 1. the `cltv_expiry_delta` for channels, `3R+2G+2S`: if in doubt, a
-	 *   `cltv_expiry_delta` of 12 is reasonable (R=2, G=1, S=2)
+	 *   `cltv_expiry_delta` of at least 34 is reasonable (R=2, G=2, S=12)
 	 */
-	/* R = 2, G = 1, S = 3 */
-	.cltv_expiry_delta = 14,
+	/* R = 2, G = 2, S = 12 */
+	.cltv_expiry_delta = 34,
 
 	/* BOLT #2:
 	 *
 	 * 4. the minimum `cltv_expiry` accepted for terminal payments: the
 	 *    worst case for the terminal node C is `2R+G+S` blocks */
-	.cltv_final = 10,
+	.cltv_final = 18,
 
 	/* Send commit 10msec after receiving; almost immediately. */
 	.commit_time_ms = 10,

lightningd/peer_htlcs.c

@@ -2278,7 +2278,7 @@ void free_htlcs(struct lightningd *ld, const struct channel *channel)
  *
  * 2. the deadline for offered HTLCs: the deadline after which the channel has
  *    to be failed and timed out on-chain. This is `G` blocks after the HTLC's
- *    `cltv_expiry`: 1 block is reasonable.
+ *    `cltv_expiry`: 1 or 2 blocks is reasonable.
  */
 static u32 htlc_out_deadline(const struct htlc_out *hout)
 {
@@ -2290,7 +2290,7 @@ static u32 htlc_out_deadline(const struct htlc_out *hout)
  * 3. the deadline for received HTLCs this node has fulfilled: the deadline
  * after which the channel has to be failed and the HTLC fulfilled on-chain
  * before its `cltv_expiry`. See steps 4-7 above, which imply a deadline of
- * `2R+G+S` blocks before `cltv_expiry`: 7 blocks is reasonable.
+ * `2R+G+S` blocks before `cltv_expiry`: 18 blocks is reasonable.
  */
 /* We approximate this, by using half the cltv_expiry_delta (3R+2G+2S),
  * rounded up. */