From 6c9180f9729cb9785892cc2d844dcc42821d6ff9 Mon Sep 17 00:00:00 2001 From: Matt Corallo Date: Wed, 22 Jan 2020 18:31:57 -0500 Subject: [PATCH] Clean up documentation around spendable outputs significantly. * Fixed a number of grammar issues * Clarified the docs for users who are intimately farmiliar with arbitrary lines of text copied from the BOLTs * Added a bit more text so that things are easier to read and less disjoint. * Clarified exactly how the witness stack should look since I had to go dig for it. --- lightning/src/chain/keysinterface.rs | 57 +++++++++++++++++----------- lightning/src/util/events.rs | 5 ++- 2 files changed, 38 insertions(+), 24 deletions(-) diff --git a/lightning/src/chain/keysinterface.rs b/lightning/src/chain/keysinterface.rs index 689a1660..b65cd0df 100644 --- a/lightning/src/chain/keysinterface.rs +++ b/lightning/src/chain/keysinterface.rs @@ -30,43 +30,56 @@ use ln::msgs; use std::sync::Arc; use std::sync::atomic::{AtomicUsize, Ordering}; -/// When on-chain outputs are created by rust-lightning an event is generated which informs the -/// user thereof. This enum describes the format of the output and provides the OutPoint. +/// When on-chain outputs are created by rust-lightning (which our counterparty is not able to +/// claim at any point in the future) an event is generated which you must track and be able to +/// spend on-chain. The information needed to do this is provided in this enum, including the +/// outpoint describing which txid and output index is available, the full output which exists at +/// that txid/index, and any keys or other information required to sign. pub enum SpendableOutputDescriptor { - /// Outpoint with an output to a script which was provided via KeysInterface, thus you should - /// have stored somewhere how to spend script_pubkey! - /// Outputs from a justice tx, claim tx or preimage tx + /// An output to a script which was provided via KeysInterface, thus you should already know + /// how to spend it. No keys are provided as rust-lightning was never given any keys - only the + /// script_pubkey as it appears in the output. + /// These may include outputs from a transaction punishing our counterparty or claiming an HTLC + /// on-chain using the payment preimage or after it has timed out. StaticOutput { - /// The outpoint spendable by user wallet + /// The outpoint which is spendable outpoint: OutPoint, - /// The output which is referenced by the given outpoint + /// The output which is referenced by the given outpoint. output: TxOut, }, - /// Outpoint commits to a P2WSH - /// P2WSH should be spend by the following witness : - /// 0 - /// With input nSequence set to_self_delay. - /// Outputs from a HTLC-Success/Timeout tx/commitment tx + /// An output to a P2WSH script which can be spent with a single signature after a CSV delay. + /// The private key which should be used to sign the transaction is provided, as well as the + /// full witness redeemScript which is hashed in the output script_pubkey. + /// The witness in the spending input should be: + /// + /// + /// Note that the nSequence field in the input must be set to_self_delay (which corresponds to + /// the transaction not being broadcastable until at least to_self_delay blocks after the input + /// confirms). + /// These are generally the result of a "revocable" output to us, spendable only by us unless + /// it is an output from us having broadcast an old state (which should never happen). DynamicOutputP2WSH { - /// Outpoint spendable by user wallet + /// The outpoint which is spendable outpoint: OutPoint, - /// local_delayedkey = delayed_payment_basepoint_secret + SHA256(per_commitment_point || delayed_payment_basepoint) OR + /// The secret key which must be used to sign the spending transaction key: SecretKey, - /// witness redeemScript encumbering output. + /// The witness redeemScript which is hashed to create the script_pubkey in the given output witness_script: Script, - /// nSequence input must commit to self_delay to satisfy script's OP_CSV + /// The nSequence value which must be set in the spending input to satisfy the OP_CSV in + /// the witness_script. to_self_delay: u16, /// The output which is referenced by the given outpoint output: TxOut, }, - /// Outpoint commits to a P2WPKH - /// P2WPKH should be spend by the following witness : - /// - /// Outputs to_remote from a commitment tx + /// An output to a P2WPKH, spendable exclusively by the given private key. + /// The witness in the spending input, is, thus, simply: + /// + /// These are generally the result of our counterparty having broadcast the current state, + /// allowing us to claim the non-HTLC-encumbered outputs immediately. DynamicOutputP2WPKH { - /// Outpoint spendable by user wallet + /// The outpoint which is spendable outpoint: OutPoint, - /// localkey = payment_basepoint_secret + SHA256(per_commitment_point || payment_basepoint + /// The secret key which must be used to sign the spending transaction key: SecretKey, /// The output which is reference by the given outpoint output: TxOut, diff --git a/lightning/src/util/events.rs b/lightning/src/util/events.rs index e810368d..eda6fc7e 100644 --- a/lightning/src/util/events.rs +++ b/lightning/src/util/events.rs @@ -99,8 +99,9 @@ pub enum Event { time_forwardable: Duration, }, /// Used to indicate that an output was generated on-chain which you should know how to spend. - /// Such an output will *not* ever be spent by rust-lightning, so you need to store them - /// somewhere and spend them when you create on-chain spends. + /// Such an output will *not* ever be spent by rust-lightning, and are not at risk of your + /// counterparty spending them due to some kind of timeout. Thus, you need to store them + /// somewhere and spend them when you create on-chain transactions. SpendableOutputs { /// The outputs which you should store as spendable by you. outputs: Vec, -- 2.30.2