In order to facilitate persistence during the funding process, added
the isPending flag to channels so that when the daemon restarts, we can
properly re-initialize the chain notifier and update the state of
channels that were going through the funding process.
In this commit the initial implementation of revocation hash
generation 'elkrem' was replaced with 'shachain' Rusty Russel
implementation which currently enshrined in the spec. This alghoritm has
the same asymptotic characteristics but has more complex scheme
to determine wish hash we can drop and what needs to be stored
in order to be able to achive full compression.
Introduce TimelockShift which is used to make sure the commitment
transaction is spendable by setting the locktime with it so that
it is larger than 500,000,000, thus interpreting it as Unix epoch
timestamp and not a block height. It is also smaller than the current
timestamp which has bit (1 << 30) set, so there is no risk of having
the commitment transaction be rejected. This way we can safely use
the lower 24 bits of the locktime field for part of the obscured
commitment transaction number.
Add tests to assert maximum state can be used. Also test
that more than one input in the commitment transaction
will fail and that having state number larger than
maxStateHint will fail.
Fix SetStateNumHint and GetStateNumHint to properly
set and get the stateNumHints using the lower 24 bits
of the locktime of the commitment transaction as the
lower 24 bits of the obfuscated state number and the
lower 24 bits of the sequence field as the higher 24
bits.
This commit fixes a bug in the wallet’s internal reservation manager
that prevented it from cleaning up the resources used by a reservation
after it was finished running through the workflow.
We fix this issue by ensuring the reservations context is deleted from
the funding limbo.
It is the callers responsibility to properly .Cancel() a reservation in
the case of an error during the funding workflow.
This commit adds an additional case of the closeObserver that will
properly handle the case of a channel being closed by a de-sync’d
commitment transaction from the PoV of the local node. In the case of a
minor 1-state divergence, the commitment transaction broadcast by the
remote node will be 1 state ahead of the commitment transaction we have
locally. This should be seen as a regular unilateral close as they
remote peer didn’t violate the channel contract in any way.
We address this case by changing the `==` to a `>=`.
This commit updates the set of channel state machine tests to properly
compile and execute with the latest set of changes to the state
machine.
Most of the changes within this commit are just renaming and field
changes as a result of the new wire messages.
The more substantial change is due to the change in semantics of the
new state machine w.r.t what has and has not been ACK’d when a new
state transition is implemented. In the case of a concurrent update
(both sides add to the log before a state transition), both sides need
to trigger a state update in order to ensure their updates have been
included.
This commit updates the internal channel state machine to the one as
described within the spec and currently implemented within the rest of
the other Lightning implementations.
At a high level the following modifications have been made:
* When signing we no loner include the index of the remote party’s
log
that our signature covers. Instead we include ALL of our current
updates, but only the updates of the remote party that we’ve
ACK’d.
* A pending change is considered ACK’d once a revocation message
has been received, locking in the changes in the remote party’s
commitment transaction.
* When sending a new commitment, we remember the index of our
log at that point so we can mark that portion of the log as ACK’d
once we receive a revocation message from the remote party.
* When receiving a new commitment signature, we include ALL of
the remote party’s changes that we’ve received but only our set
of changes that’ve been ACK’d by the remote party.
* Implicitly a revocation message now also implicitly serves to ACK
all the changes that were included in the CommitSig message
received before it.
The resulting change is a rather minor diff. However, with this state
machine it’s important to note that the order to sig/revoke messages
has been swapped. A proper exchange now looks like the following:
* Alice -> Add, Add, Add
* Alice -> Sig
* Revoke <- Bob
* Sig <- Bob
* Alice -> Revoke
One other thing that’s worth noting is that with this state machine,
since what’s included in an update is implicit, both side may need to
at times send a new commitment update in the case of a concurrent state
transition initiated by both sides.
Finally, all counters/indexes have been made 64-bit integers in order
to properly match the spec.
This commit adds a new struct to the channel state machine: updateLog.
updateLog encapsulates the update log linked list itself, a series of
new counters we’ll need in order to switch to the spec’s state machine
and also the index into the log itself. This new struct serves to
simplify much of the logic surrounding the update log and also
elminates a bit of code duplication within the current state machine.
This commit only adds the new struct. The rest of the state machine
will be updated in a later commit to use the new log and its new
counters.
This commit fixes a bug in the LightingChannel commitment state machine
which could occasionally result in the total number of satoshis sent or
received being counted twice if a redundant state transition were
initiated.
To fix this bug, we now only increment the number of satoshi
sent/recv’d iff it’s the first time the HTLC has been processed.
This commit ensures that when a channel’s closeObserver is signaled to
exit before a channel closure has been detected, then the resources
dedicated to the pending spend notification can be freed up.
rHashMap is used to store the PaymentDescriptor belonging to a received
HTLC's revocation hash. This improves the efficiency of looking up
PaymentDescriptors from their RHash whenever we want to settle or cancel
that HTLC.
This commit fixes a bug which would cause the node on the _receiving_
side of a channel force close to be blind of their immediately funds
on-chain. The root of the issue was that within the btcwallet
implementation of the WalletController method ‘NewRawKey’, the wallet
wouldn’t request notifications for the new address, as the direct
function from the waddrmgr was used which skips registration of the new
address.
To fix, this, we now ensure that btcwallet will receive notifications
for keys used within the raw p2wkh commitment output. This ensures that
the wallet is aware of funds that are made available as a result of a
channel force closure by the channel counter party.
This commit fixes a slight scripting related issue as a result of
default policy in Bitcoin Core 0.13.1. With this version of Bitcoin
Core, nodes will now enforce a policy that ensures the first argument
of OP_IF is either an empty vector or a 0x01 value. Our current sent of
functions to generate the witness for the delay clause of the
commitment transaction instead uses a 0x00 value rather than an empty
byte vector.
With this commit we fix the issue by ensuring that we use an empty
vector rather an 0x00 for forcing the commitment delay script pathway.
This commit adds the ability to cancel a channel’s internal
closeObserver goroutine by adding a new public facing Stop method.
Additionally, we now make passing a ChainNotifier interface completely
optional. If the ChainNotifier isn’t passed in as a constructor, then
the closeObserver goroutine will never be launched. This new feature
lets the caller ensure that only a single closeObsever for any given
channels exists.
This commit removes the BlockChainIO interface as a dependency to the
LightningChannel struct as the interface is no longer used within the
operation of the LightningChannel.
This commit ensures that we now properly handle and propagate errors
that arise when attempting to create a new channel after the funding
transaction is believed to be confirmed.
A previous edge case would arise when a user attempted to create a new
channel, but their corresponding btcd node wasn’t yet fully synced.
This commit fixes a prior bug in the wallet triggered by the creation
of a channel using the single funder workflow, but pushing exactly
*half* of the channel over to the other side. The prior logic to
determine who the initiator would result in a disagreement over who
created the channel initially. This wouldn’t manifest until the channel
was attempted to be closed cooperatively. As both side disagreed about
who created the channel they would apply the closing fee to different
outputs, thereby creating mismatched closing transaction. The signature
would fail to validate as the closer will create a different
transaction from that of the responder.
This commit fixes the issue by properly detecting who initially created
the channel.
This commit fixes a bug introduced by the past attempt to Make Logging
Great Again. Since we unset the curve parameters when reading/writing
the messages, if we have a lingering reference that’s active elsewhere
in the daemon, then we’ll modify that reference. To fix this, we now
explicitly set the Curve parameters in two areas.
A similar commit has been pushed to lightning-onion.
This commit modifies the closeObserver goroutine to ensure that a close
summary has been inserted into the database before signalling any
observers that a unilateral channel closure was detected. This fixes a
slight bug where a peer would force close a channel, but we wouldn’t
properly detect that and clean up the channel state if had a failed
cooperative channel closure.
This commit modifies the logic of the closeObserver slightly to not
incorrectly mark the broadcast of the commitment transaction triggered
by a cooperative channel closure as an unprompted broadcast.
This commit adds support to the wallet’s internal funding workflow for
pushing a certain amount of BTC to the responder’s side for a single
funder workflow as part of the first commitment.
This commit modifies the logic around adding cancel entries to the
update log for the commitment state machine slightly by also including
the r-hash of the HTLC that’s been cancelled in the entry for the
cancellation. With this change, we can accurately track which HTLC is
being cancelled within outer sub-systems.
This commit alters the new HTLC cancellation logic to instead allow the
canceller of an HTLC to cancel the HTLC by the payment hash rather than
the index of the HTLC.
This commit adds the ability to send/recv HTLC cancellation to the
commitment state machine. Previously this feature had been
unimplemented within the state machine, with only adds/settles working.
With this change, there’s now now no concept of “timing” out HTLC’s,
only the cancellation of HTLC’s which may be triggered for various
reasons.
This commit makes a large number of minor changes concerning API usage
within the deamon to match the latest version on the upstream btcsuite
libraries.
The major changes are the switch from wire.ShaHash to chainhash.Hash,
and that wire.NewMsgTx() now takes a paramter indicating the version of
the transaction to be created.
This commit partially rectifies a quick hack that was previously thrown
in to address an issue discovered due to possible state inconsistencies
between an active channel object and the daemon’s breachAbrbiter.
A prior commit has modified the interaction between the peer and the
breachArbiter to eliminate the state in consistency. Therefore, we no
longer need to access the database to ensure that we’re observing the
latest channel state in order to correctly make a decision about
whether a broadcast commitment transaction is a breach or not.
This commit fixes an unnoticed bug within btcwallet’s implementation of
the BlockChainIO interface, specifically the GetUtxo method. In order
to maintain compatibility with Bitcoin Core’s gettxout method, btcd
doesn’t return an error if the targeted output is actually spent.
We weren’t properly detecting this, but we do now by creating a new
error which is returned in the case of a nil error but a nil return
value.
This commit slightly modifies the channel reservation workflow to
expose the new information conerning the exact confirmation location of
the channel provided by the ChainNotifier. The DispatchChan() method of
the ChannelReservation now also returns the blockHeight and txIndex
where the transaction was ultimately confirmed. This information will
be needed by the fundingManager so it can properly generate the
authenticated channel announcement proofs.
This commit fixes a bug within the btcwallet implementation of the
BlockChainIO interface. The exact nature of the bug was a rounding
error that would only manifest if the value of the UTXO was below 1
BTC.
The tests within this package currently test channels with mostly whole
values of BTC, as a result the bug went unnoticed until now.
The fix itself is trivial: convert to an int64 AFTER performing the
multiplication to convert to satoshis from Bitcoin.
This commit modifies the attributes of the LightningChannel struct to
publicly expose the funding keys used within the channel for the local
and remote party. Exposing these keys publicly will allow callers to
use the keys involved to generate authenticated channel advertisements
for the routing layer.
This commit expands the data returned by the current GetCurrentHeight
to also return the current best block hash, expanding the method into
GetBestBlock. Additionally, the current best BlockHash is also now
displayed within the GetInfo RPC call.
This commit fixes a lingering bug within the channel funding
reservation workflow that caused the address of a channel counter-party
to not be written to disk, resulting in an error on start up. To fix
this, we now properly populate the node’s TCP address when initiating
the reservation.
This commit adds a new method to the WalletController interface:
IsSynced. The role of the function is to query the local wallet about
if it thinks it has fully synced to the tip of the current main chain.
This function can be useful within U.I’s to block off certain
functionality until the wallet is fully synced to the main chain.
This commit modifies the channel closing logic to remove the hard coded
bools indicating which side is attempting the closure. With the recent
changes, the initiator must always pay the channel closure fees.
This information is recently stored on disk, therefore we can use the
boolean to ensure that the closure transaction is created properly no
matter who initiates the close.
This fixes a bug.
This commit introduces a new sub-system into the daemon whose job it is
to vigilantly watch for any potential channel breaches throughout the
up-time of the daemon. The logic which was moved from the utxoNursery
in a prior commit now resides within the breachArbiter.
Upon start-up the breachArbiter will query the database for all active
channels, launching a goroutine for each channel in order to be able to
take action if a channel breach is detected. The breachArbiter is also
responsible for notifying the htlcSwitch about channel breaches in
order to black-list the breached linked during any multi-hop forwarding
decisions.
This commit adds detection of contract breaches within the commitment
state-machine for a channel. A contract breach is defined as the event
wherein a channel counter-party broadcasts a previously revoked
commitment transaction. Such an event immediately closes a channel as
the funds are now in a state of dispute.
Once a breach is detected, a snapshot of the breached state is
retrieved from the database’s revocation log. This snapshot is then
used to generate the revocation leaf used within this particular state
along with all the other information ncessary to sweep ALL active funds
within the channel. This information is encapsulated within the
BreachRetribution struct which is sent over a new channel dedicated to
sending/receiving BreachRetributions.
This commit modifies the logic within the state machine to properly
populate the new field of `OutputIndex` which the HTLC stored within a
channel delta.
With this change, in the future we’ll be able to quickly locate a
particular HTLC output in the scenario that the commitment transaction
has been broadcast on-chain and we need to sweep it. Allocating a few
extra bytes on-disk saves us from the guess-and-check logic+code
required otherwise.
This commit adds some necessary locking to ensure that all updates to
the internal state of the commitment state machine are fully serial and
thread-safe. This change is required to ensure future actions w.r.t
taking action once a revoked commitment transaction has been broadcast
are not carried out while the channel’s state is being updated.
This commit extends the SignDescriptor with a single attribute, the
‘PrivateTweak’. The duties of the Signer interface have also been
augmented to properly derive a private key using the specified tweak,
iff it’s non-nil.
As currently defined in order to generate the proper private key based
off of a PrivateTweak, the signer is to add the tweak value to the
private key for the specified public key. This generated value is to be
used for signing within the specified context.
This change paves the way for automatic revoked output sweeping with
signatures generated directly by the Signer interface, maintaining the
structure of the abstraction.
A test has been added at the interface level in order to excerise each
WalletController’s implementation of the key derivation as currently
defined.
This commit converts the rearming two commitment spend functions to use
the lnwallet.Signer interface directly rather than manually manage
private keys during the signing process. This commit is in preparation
for implementation of fully automated revoked uncooperative closure
detection and retribution.
This commit finalizes the implementation of #58 by integrating passing
around the obfuscate state hints into the funding workflow of the
wallet, and also the daemon’s funding manager.
In order to amend the tests, the functions to set and receive the state
hints are now publicly exported.
This commit modifies the channel state machine slightly to encode the
current state number using 30-bits of the sequence number within the
commitment transaction’s only input.
Such a modification reduces up the processing time required to punish
the counter party for breaching the contract established within the
channel by broadcasting an older revoked state.
This fixes#58 with a minor modification to what was originally
suggested.
This commit adds two utility functions along with corresponding tests
for adding obfuscated state number hints to each commitment
transaction.
Such a feature reduces the search time to recover the necessary
material to punish a counterpaty for broadcasting an invalid state from
O(N), to O(1), where N is the number of states in the channel’s
transcript. By encoding the obsfucated state number, either side is
able to quickly obtain the ncessary state to excerise “justice”.
This commit modifies the existing channel reservation workflow slightly
to thread through the IP address that we were able to reach the node
at, or the one which the node reached us via. Additionally, rather than
using OpenChannel.FullSync() at the end of the reservation workflow, we
now use OpenChannel.FullSyncWithAddr() in order to create the
relationship in the database between the channel, and the p2p node we
created the channel with.
All tests, as well as a portion of the fundingManager have been updated
accordingly,
This commit modifies the lnwallet code and related tests in order to
adhere to the recent field-name change to channeldb.OpenChannel.
Instead of having the field ‘TheirLNID’ which is the sha256 of the
node’s public key, we now instead use the public key directly in all
contexts.
This commit consists of a mass variable renaming to call the pkScript being executed for segwit outputs the `witnessScript` instead of `redeemScript`. The latter naming convention is generally considered to be reserved for the context of BIP 16 execution. With segwit to be deployed soon, we should be using the correct terminology uniformly through the codebase.
In addition some minor typos throughout the codebase has been fixed.
This commit returns the BtcWallet wrapper struct back to conformance to
the WalletController interface by adding support for
SubscribeTransactions.
The implementation of the lnwallet.TransactionSubscription consists
simply of a proxy goroutine which forwards notifications from the
wallet’s internal NotificaitonServer.
This commit adds a new simple interface related to the WalletController
which allows for subscribing to new notifications as transactions
relevant to the wallet are seen on at the network and/or mined. The
TransactionSubscription interface will prove useful for building higher
level UI’s on-top of the daemon which update the presentation layer in
response to received notifications.
This commit implements the new ListTransactionDetails method within
btcwallet’s concrete implementation of the WalletController interface.
Both mined and unmined transactions are currently returned via the same
method. Unmined transactions are indicated by their lack of an
inclusion block hash and lack of confirmations.
This commit modifies the prior funding workflow to account for fees
when creating the funding output. As a stop gap, the current fee for
the commitment transaction is now hard-coded at 5k satoshis. Once the
fee models are in place this should instead be some high multiple of
the current “average” fee rate within the network, continuing, the
proper fee should be adjusted from the commitment transaction has
outputs are added/removed.
This commit introduces the concept of a manually initiated “force”
closer within the channel state machine. A force closure is a closure
initiated by a local subsystem which broadcasts the current commitment
state directly on-chain rather than attempting to cooperatively
negotiate a closure with the remote party.
A force closure returns a ForceCloseSummary which includes all the
details required for claiming all rightfully owned outputs within the
broadcast commitment transaction.
Additionally two new publicly exported channels are introduced, one
which is closed due a locally initiated force closure, and the other
which is closed once we detect that the remote party has executed a
unilateral closure by broadcasting their version of the commitment
transaction.
This commit slightly modifies btcwallet’s SignOutputRaw method to work
properly in the case that the pkScript of the output being spent isn’t
one of the template pkScripts (p2pkh, multi-sig, etc). Rather than
examining the address, we now attempt to find the private key which
matches the public key passed within the sign descriptor.
This commit adds full persistence logic of the current lowest
un-revoked height within each commitment chain. The newly added
channeldb methods for record state transitions within both commitment
chains are now utilized. This un-settled HTLC state is now read upon
initialization, with the proper log entries inserted into the state
update log which reflect the garbage collected log right before the
restart.
A new set of tests have been added to exercise a few edge cases around
HTLC persistence to ensure the in-memory log is properly restored based
on the on-disk snapshot.
This commit implements a state update log which is intended the record
the relevant information for each state transition on disk. For each
state transition a delta should be written recording the new state. A
new method is also provided which is able to retrieve a previous
channel state based on a state update #.
At the moment no measures has been taken to optimize the space
utilization of each update on disk. There are several low-hanging
fruits which can be addressed at a later point. Ultimately the update
log itself should be implemented with an append-only flat file at the
storage level. In any case, the high level abstraction should be able
to maintained independent of differences in the on-disk format itself.
This commit removes a flaky assertion within the interaction tests. Due
to differences in final coin selection across tests due to the
pseudo-random nature of map iterations, a single output might be
selected rather than two as we previously expected.
Additionally a duplicate test has been removed, and the locked output tests
simplified a bit.
This commit performs a major refactor of the current wallet,
reservation, and channel code in order to call into a WalletController
implementation rather than directly into btcwallet.
The current set of wallets tests have been modified in order to test
against *all* registered WalletController implementations rather than
only btcwallet. As a result, all future WalletControllers primary need
to ensure that their implementation passes the current set of tests
(which will be expanded into the future), providing an easy path of
integration assurance.
Rather than directly holding the private keys throughout funding and
channel creation, the burden of securing keys has been shifted to the
specified WalletController and Signer interfaces. All signing is done
via the Signer interface rather than directly, increasing flexibility
dramatically.
During channel funding, rather than creating a txscript.Engine to
verify commitment signatures, regular ECDSA sig verification is now
used instead. This is faster and more efficient.
Finally certain fields/methods within ChannelReservation and
LightningChannel have been exposed publicly in order to restrict the
amount of modifications the prior tests needed to undergo in order to
support testing directly agains the WalletController interface.
This commit modifies the elkrem root derivation for each newly created
channel. First a master elkrem root is derived from the rood HD seed
generated from private wallet data. Next, a HKDF is used with the
secret being the master elkrem root.
This file is no longer needed as each implementation of the
WalletController is expected to handle its own set up via an instance
of the WalletDriver factory struct.
This commit adds the first concrete implementation of the
WalletController interface: BtcWallet. This implementation is simply a
series of wrapper functions are the base btcwallet struct.
Additionally, for ease of use both the BlockChain IO and Signer
interface are also implemented by BtcWallet. Finally a new WalletDriver
implementation has been implemented, and will be register by the init()
method within this new package.
This commit revamps the previous WalletController interface, edging it
closer to a more complete version.
Additionally, this commit also introduces two new interfaces:
BlockchainIO, and Singer along with a new factor driver struct, the
WalletDriver.
This BlockChainIO abstracts read-only access to the blockchain, while
the Singer interface abstracts the signing of inputs from the base
wallet paving the way to hardware wallets, air-gapped signing, etc.
Finally, in order to provide an easy method for selecting a particular
concrete implementation of a WalletController interface, the concept of
registering “WalletDriver”s has been introduced. A wallet driver is
essentially the encapsulation of a factory function capable of create a
new instance of a Wallet Controller.
This commit removes the wrapper functions used to rely on the coinset
package for coin selection. In a future commit the prior behavior will
be replaced by a custom coin selection implementation which estimates
the size of the funding transaction.
This commit refactors the code within lnwallet interacting with the
ChainNotifier to accept, and call against the implementation rather
than a single concrete implementation.
LightningWallet no longer creates it’s own BtcdNotifier implementation
doing construction, now instead accepting a pre-started `ChainNotifier`
interface. All imports have been updated to reflect the new naming
scheme.
This commit fixes a bug in the lockTimeToSequence function when mapping
a block-based relative lock time to the proper sequence number.
Applying the mask isn’t necessary since the values are expected to be
blow 65K blocks.
This commit adds a basic test for cooperative channel closure. The
current test ensures correctness of the cooperative closure procedure
initiated by either the channel initiator, or the channel responder.
This commit adds glide integration in order to make lnd builds fully
reproducible. Rather than using “go get” users should now manually pull down
the repo, use glide to fetch+install the dependancies, then manually install
all related binaries.
With this change we no longer have to chase dependancies making breaking API
changes under us. We can manually update the managed dependancies once a new
stable release of a defendant package is released.
Additionally, reproducible builds are a strong requirement in order to securely
distribute future major releases of lnd.
This commit adds a new method, “PendingUpdates” to the channel state
machine which is intended to be a source to give callers a hint as to
when an additional commitment signature should be sent independent of
any request/response book keeping.
This commit patrons the state update logs properly within the channel
state machine. This change fixes a number of bugs caused by treating a
central log as two logically distinct logs. Rather than having a bit
indicating if the entry is incoming/outgoing, an entry is added to a
remote or local log depending on which modification method is used.
As a result the code is much easier to follow due to separation of
concerts.
Finally, when attempting to sign a new update with an exhausted
renovation window a distinct error is returned in order to allow higher
level callers to properly back-off and handle the protocol event.
This commit fixes a slight bug in the channel state machine’s code
executed when processing a revocation messages. With this commit after
processing a revocation, log entries which we should forward to the
downstream or upstream peer for settling/adding HTLC’s are now properly
returned.
The testa have also been updated to ensure to correct htlc’s are
returned “for forwarding”.
We no longer track HTLC’s by their r-hash within the log into the
index, as we may have multiple HTLC’s that can be redeemed by the same
pre-image. Instead we now use a separate index which is keyed by a
log-index.
Additionally, the SettleHTLC method now also returns the index of the
HTLC being settled which allows the remote party to quickly locate the
HTLC within their log.
This commit also introduces a few trace/debug log messages which will
likely be pruned in the near future
This commit finishes the initial draft of the commitment state machine.
A full re-write of the prior protocol which combines aspects of the
former ‘lnstate’ package has replaced the prior un-finished
stop-and-wait protocol.
This new protocol is designed to operate in an asynchronous environment
and to facilitate non-blocking batched and pipelined updates to the
committed channel states. The protocol is also de-synchronized meaning
that either side can propose new commitment states independent of the
actions of the other party.
The state machine implemented is very similar to that of c-lightning,
however we allow multiple unrevoked commentates in order to minimize
blocking, and also to reduce latency across several hops in a
bi-directional setting.
The current implementation consists of 3 main data structures: a
commitment chain which consist of unrevoked commitment transactions
(one for each side), and a (mostly) append-only log of HTLC updates
shared between both sides. New commitments proposed index into the log
denoting which updates they include, this allows both parties to
progress chains independent of one another. Revoked commitments, reduce
the length of the chain by one, and free up space within the revocation
window.
At this point only basic tests are in place for the state machine,
however more extensive testing infrastructure along with formal proofs
using PlusCall are planned.
This commit changes prior behavior which stored a “hot” commitment
transaction, meaning one which all the sigScript fully assembled and
able to be broadcast.
Instead, we now store the current signature for our commitment
transaction as a separate field within the database and within memory.
As a result, this eliminates a class of bugs which would erroneously
broadcast a fully loaded commitment transaction, either leading to a
loss of funds, or suspending availability to funds for a period of
time.
This update the wallet to implement the new single funder workflow
which uses revocation keys rather than revocation hashes for the
commitment transactions.
The derivation is current bed on an HKDF invocation using our private
key as the secret, and the node’s channel multi-sig key as the salt.
This scheme allows us to derive the key on the fly given data known to
only us and the remote node.
The current derivation is just a place-holder and will be re-visited at
a later time.
With this commit, the reservation workflow for the single funder use
case is now aware of the usage of revocation keys.
The changes are relatively minor:
* contributions now have RevocationKeys instead of RevocationHashes
* CompleteReservationSingle now takes the initiators revocation key
This commit implements the “send coins” RPC request which was
introduced at both the lnrpc and command line level in a prior commit.
A small refactoring has taken place w.r.t to sendmany+sendcoins in
order to eliminate some code duplication.
This commit updates the previous HTLC and commitment scripts to their
current latest evolution.
The HTLC scripts have been optimized for space savings, the
functionality itself has remained relatively unchanged. A trade off was
made to add additional bytes into the sigScript in order to avoid
extraneous CHECKSIG’s. The rationale is that an extra 1-2 bytes in the
sigScript to guide execution, are worthwhile since they’re in the
witness, and witness data may be pruned in the near future.
The primary change is within the commitment transaction itself. Instead
of using revocation hashes, we now use signature based revocation. This
saves space in the Script, and optimizes away an extra hashing
operation. Elkrem/shachain is still used but, we now use the pre-images
to homomorphically derive a public key which the other party will be
able to sign with, once we disclose the pre-image itself.
Finally, we have switched to using SHA-256 everywhere uniformly for
both revocation hashes, and payment hashes. The rationale is that the
output of ripemd160 is too small for modern security margins, and that
other coins/chains are more likely to have SHA-256 implemented, than
ripemd160.
A set of tests has also been included which contain (mostly) exhaustive
tests of all possible redemption paths for both commitment and HTLC.
This unifies some inconstancies across the code-base with hashes being
32 vs 20 bytes. All hashes, whether payment or revocation are now
uniformly 32 bytes everywhere. As a result, only OP_SHA256 will be used
within commitment and HTLC scripts. The rationale for using sha256
instead of hash160 for the HTLC payment pre-image is that alternative
chains are more likely to have sha256 implemented, rather than
ripemd160.
A forthcoming commit will update the current commitment, and HTLC
scripts.
This commit introduces the fundingManger which is used as a bridge
between the wallet’s internal ‘ChannelReservation’ workflow, and the
wire protocol’s funding messages.
The funding manger is responsible for progressing the workflow, and
communicating any errors generated during the workflow back to the
source peer.
This commit adds additional test cases to test both cases (initiator vs
responder) for a single funder channel workflow. Additionally, the
previous dual funder tests have been extended in order to detect proper
funding channel broadcast, and the ChainNotifier’s role in notifying
upstream callers that a funding transaction has been embedded in the
chain at a sufficient depth.
At this point the tests certainly need to be cleaned up. bobNode should
be replaced with a second instance of the wallet modeling a remote
peer.
This commit modifies the existing workflow to add additional paths to
be used when on the responding side of a single funder workflow.
Additionally, several bugs encountered within the existing dual funder
workflow logic have been fixed, and modified to account for the wallet
being on the igniting side of a single funder workflow.
The previous logic incorrectly assumed the returned address was already
a p2wkh address. Instead, a p2sh address was returned. So we now
correctly craft both the sigScript and witness stack for a nested p2sh
spend.
This is required since for single funder channels, we don’t contribute
any funds so we don’t need to select any change or coins for input into
the funding transaction.
This commit adds 3 methods to lnwallet.ChannelReservation intended to
facilitating a single funder channel workflow between two nodes. A
single funder workflow is characterized as the initiator committing all
the funds to a channel, with the responder only providing public keys,
and a revocation hash.
The workflow remains the same for the initiator of the funding
transaction, however for the responder, the following methods are
instead called in order:
* .ProcessSingleConribution()
* .CompleteSingleContribution()
* .FinalizeReservation()
These methods are required for the responder as they are never able to
construct the full funding transaction, and only receive the out point
of the funding transaction once available.
A cooperative closure of a LightningChannel proceeds in two steps.
First, the party who wishes to close the channel sends a signature for
the closing transaction. Next, the responder reconstructs the closing
transaction identically as the initiator did using a canonical
input/output ordering, and the currently settled balance within the
channel. At this point, the responder then broadcasts the closure
transaction. It is the responsibility of the initiator to watch for
this transaction broadcast within the network to clean up any resources
they committed to the active channel.
Only nested p2sh or pure witness outputs are used when selecting coins
for inputs to a funding transaction.
The funding transaction output now uses p2wsh rather than regular p2sh.
All tests have been updated accordingly.
