From 8f0cd90c6ce08c30d07bdfdba28b3a0e2c929dfe Mon Sep 17 00:00:00 2001
From: Matt Corallo <git@bluematt.me>
Date: Fri, 4 Feb 2022 17:39:46 +0000
Subject: [PATCH] fix serialization backwards compat

---
 lightning/src/ln/channel.rs | 28 +++++++++++++++++++++++-----
 1 file changed, 23 insertions(+), 5 deletions(-)

diff --git a/lightning/src/ln/channel.rs b/lightning/src/ln/channel.rs
index 72f6df1e..82ad6c88 100644
--- a/lightning/src/ln/channel.rs
+++ b/lightning/src/ln/channel.rs
@@ -39,7 +39,7 @@ use util::events::ClosureReason;
 use util::ser::{Readable, ReadableArgs, Writeable, Writer, VecWriter};
 use util::logger::Logger;
 use util::errors::APIError;
-use util::config::{UserConfig,ChannelConfig,ChannelHandshakeConfig};
+use util::config::{UserConfig,ChannelConfig};
 use util::scid_utils::scid_from_parts;
 
 use io;
@@ -5193,7 +5193,6 @@ impl<Signer: Sign> Writeable for Channel<Signer> {
 		self.config.forwarding_fee_proportional_millionths.write(writer)?;
 		self.config.cltv_expiry_delta.write(writer)?;
 		self.config.announced_channel.write(writer)?;
-		// self.config.commit_upfront_shutdown_pubkey.write(writer)?;
 		self.commit_upfront_shutdown_pubkey.write(writer)?;
 
 		self.channel_id.write(writer)?;
@@ -5437,6 +5436,7 @@ impl<Signer: Sign> Writeable for Channel<Signer> {
 			(9, self.target_closing_feerate_sats_per_kw, option),
 			(11, self.monitor_pending_finalized_fulfills, vec_type),
 			(13, self.channel_creation_height, required),
+			(15, self.commit_upfront_shutdown_pubkey, required),
 		});
 
 		Ok(())
@@ -5458,12 +5458,12 @@ impl<'a, Signer: Sign, K: Deref> ReadableArgs<(&'a K, u32)> for Channel<Signer>
 			config.as_mut().unwrap().forwarding_fee_proportional_millionths = Readable::read(reader)?;
 			config.as_mut().unwrap().cltv_expiry_delta = Readable::read(reader)?;
 			config.as_mut().unwrap().announced_channel = Readable::read(reader)?;
-			// config.as_mut().unwrap().commit_upfront_shutdown_pubkey = Readable::read(reader)?;
+			config.as_mut().unwrap().commit_upfront_shutdown_pubkey = Some(Readable::read(reader)?);
 		} else {
 			// Read the 8 bytes of backwards-compatibility ChannelConfig data.
 			let mut _val: u64 = Readable::read(reader)?;
 		}
-		let handshake_config = Some(ChannelHandshakeConfig::default());		let channel_id = Readable::read(reader)?;
+		let channel_id = Readable::read(reader)?;
 		let channel_state = Readable::read(reader)?;
 		let channel_value_satoshis = Readable::read(reader)?;
 
@@ -5677,6 +5677,7 @@ impl<'a, Signer: Sign, K: Deref> ReadableArgs<(&'a K, u32)> for Channel<Signer>
 		// only, so we default to that if none was written.
 		let mut channel_type = Some(ChannelTypeFeatures::only_static_remote_key());
 		let mut channel_creation_height = Some(serialized_height);
+		let mut commit_upfront_shutdown_pubkey = None;
 		read_tlv_fields!(reader, {
 			(0, announcement_sigs, option),
 			(1, minimum_depth, option),
@@ -5689,6 +5690,7 @@ impl<'a, Signer: Sign, K: Deref> ReadableArgs<(&'a K, u32)> for Channel<Signer>
 			(9, target_closing_feerate_sats_per_kw, option),
 			(11, monitor_pending_finalized_fulfills, vec_type),
 			(13, channel_creation_height, option),
+			(15, commit_upfront_shutdown_pubkey, option),
 		});
 
 		let chan_features = channel_type.as_ref().unwrap();
@@ -5703,12 +5705,28 @@ impl<'a, Signer: Sign, K: Deref> ReadableArgs<(&'a K, u32)> for Channel<Signer>
 			return Err(DecodeError::InvalidValue);
 		}
 
+		if commit_upfront_shutdown_pubkey.is_none() {
+			// commit_upfront_shutdown_pubkey has moved around a good bit, in version 1
+			// serialization, it was written out as a part of the explicit field list of the
+			// `ChannelConfig`. Then, it was written out as a field in the `ChannelConfig` itself.
+			// Now, it is written out explicitly as its own TLV (as the field has moved to
+			// `ChannelHandshakeConfig`).
+			// Thus, if its not in a TLV, we here pull it from the `ChannelConfig`, and if we can't
+			// find it at all, fail.
+			let legacy_commit_upfront_shutdown_pubkey = config.as_ref().unwrap().commit_upfront_shutdown_pubkey;
+			if let Some(val) = legacy_commit_upfront_shutdown_pubkey {
+				commit_upfront_shutdown_pubkey = Some(val);
+			} else {
+				return Err(DecodeError::InvalidValue);
+			}
+		}
+
 		let mut secp_ctx = Secp256k1::new();
 		secp_ctx.seeded_randomize(&keys_source.get_secure_random_bytes());
 
 		Ok(Channel {
 			user_id,
-			commit_upfront_shutdown_pubkey: handshake_config.unwrap().commit_upfront_shutdown_pubkey,
+			commit_upfront_shutdown_pubkey: commit_upfront_shutdown_pubkey.unwrap(),
 			config: config.unwrap(),
 			channel_id,
 			channel_state,
-- 
2.30.2