From: Wilmer Paulino <wilmer@wilmerpaulino.com>
Date: Fri, 28 Apr 2023 09:06:23 +0000 (-0700)
Subject: Check difficulty transition against `Target` instead of `Work`
X-Git-Tag: v0.0.116-alpha1~37^2~2
X-Git-Url: http://git.bitcoin.ninja/?a=commitdiff_plain;h=4f9bcb9958d0981dbc69fcbee70fcc847f786392;p=rust-lightning

Check difficulty transition against `Target` instead of `Work`

`rust-bitcoin v0.30.0` made some changes in this area that no longer
allow us to work with the previously exposed `U256` type. While `Work`
and `Target` (they're inverses of each other) essentially represent the
same concept, it makes more sense from their API's perspective to only
expose difficulty transitions and adjustments on `Target`s.
---

diff --git a/lightning-block-sync/src/poll.rs b/lightning-block-sync/src/poll.rs
index 9f7e8becf..e7171cf36 100644
--- a/lightning-block-sync/src/poll.rs
+++ b/lightning-block-sync/src/poll.rs
@@ -136,8 +136,11 @@ impl ValidatedBlockHeader {
 
 		if let Network::Bitcoin = network {
 			if self.height % 2016 == 0 {
-				let previous_work = previous_header.header.work();
-				if work > (previous_work << 2) || work < (previous_work >> 2) {
+				let target = self.header.target();
+				let previous_target = previous_header.header.target();
+				let min_target = previous_target >> 2;
+				let max_target = previous_target << 2;
+				if target > max_target || target < min_target {
 					return Err(BlockSourceError::persistent("invalid difficulty transition"))
 				}
 			} else if self.header.bits != previous_header.header.bits {