Users commonly want to know what their balance was when a channel
was closed, which this provides in a somewhat simplified manner.
It does not consider pending HTLCs and will always overstate our
balance by transaction fees.
A `DNSResolverMessageHandler` which handles resolution requests
should want the `NodeFeatures` included in the node's
`node_announcement` to include `dns_resolver` to indicate to the
world that it provides that service. Here we enable this by
requesting extra feature flags from the `DNSResolverMessageHandler`
in the features `OnionMessenger`, in turn, provides to
`PeerManager` (which builds the `node_announcement`).
This feature bit is used to indicate that a node will make DNS
queries on behalf of onion message senders, returning DNSSEC TXT
proofs for the requested names.
It is used to signal support for bLIP 32 resolution and can be used
to find nodes from which we can try to resolve BIP 32 HRNs.
While `message_received` purports to be called on every message,
prior to the message, doing so on `Init` messages means we have to
call `message_received` while holding the per-peer mutex, which
can cause some lock contention.
Instead, here, we call `message_received` after processing `Init`
messages (which is probably more useful anyway - the peer isn't
really "connected" until we've processed the `Init` messages),
allowing us to call it unlocked.
`creates_and_pays_for_offer_with_retry` intends to check that we
re-send a BOLT 12 `invoice_request` in response to a
`message_received` call, but doesn't actually test that there were
no messages in the outbound buffer after the initial send, which we
do here.
This adds a new utility struct, `OMNameResolver`, which implements
the core functionality required to resolve Human Readable Names,
namely generating `DNSSECQuery` onion messages, tracking the state
of requests, and ultimately receiving and verifying `DNSSECProof`
onion messages.
It tracks pending requests with a `PaymentId`, allowing for easy
integration into `ChannelManager` in a coming commit - mapping
received proofs to `PaymentId`s which we can then complete by
handing them `Offer`s to pay.
It does not, directly, implement `DNSResolverMessageHandler`, but
an implementation of `DNSResolverMessageHandler` becomes trivial
with `OMNameResolver` handling the inbound messages and creating
the messages to send.
BIP 353 `HumanReadableName`s are represented as `₿user@domain` and
can be resolved using DNS into a `bitcoin:` URI. In the next
commit, we will add such a resolver using onion messages to fetch
records from the DNS, which will rely on this new type to get name
information from outside LDK.
This creates the initial DNSSEC proof and query messages in a new
module in `onion_message`, as well as a new message handler to
handle them.
In the coming commits, a default implementation will be added which
verifies DNSSEC proofs which can be used to resolve BIP 353 URIs
without relying on anything outside of the lightning network.
When we make a DNSSEC query with a reply path, we don't want to
allow the DNS resolver to attempt to respond to various nodes to
try to detect (through timining or other analysis) whether we were
the one who made the query. Thus, we need to include a nonce in the
context in our reply path, which we set up here by creating a new
context type for DNS resolutions.
We often process many gossip messages in parallel across different
peer connections, making the `NetworkGraph` mutexes fairly
contention-sensitive (not to mention the potential that we want to
send a payment and need to find a path to do so).
Because we need to look up a node's public key to validate a
signature on `channel_update` messages, we always need to take a
`NetworkGraph::channels` lock before we can validate the message.
For simplicity, and to avoid taking a lock twice, we'd always
validated the `channel_update` signature while holding the same
lock, but here we address the contention issues by doing a
`channel_update` validation in three stages.
First we take a read lock on `NetworkGraph::channels` and check if
the `channel_update` is new, then release the lock and validate the
message signature, and finally take a write lock, (re-check if the
`channel_update` is new) and update the graph.
DefaultRouter::create_blinded_payment_paths may creat a one-hop blinded
path with the recipient as the introduction node. Update the privacy
section of DefaultRouter's docs to indicate this as is done in the docs
for DefaultMessageRouter.
ChannelManager is parameterized by a Router, which must also implement
MessageRouter. Instead, add a MessageRouter parameter such that the
Router and MessageRouter traits can be de-coupled. This simplifies using
something other than DefaultMessageRouter, which DefaultRouter currently
delegates to.
We expect our users to have fully idempotent `Event` handling as we
may replay events on restart for one of a number of reasons. This
isn't a big deal as long as all our events have some kind of
identifier users can use to check if the `Event` has already been
handled.
For outbound payments, this is the `PaymentId` they provide in the
send methods, however for inbound payments we don't have a great
option.
`PaymentHash` largely suffices - users can simply always claim in
response to a `PaymentClaimable` of sufficient value and treat a
`PaymentClaimed` event as duplicate any time they see a second one
for the same `PaymentHash`. This mostly works, but may result in
accepting duplicative payments if someone (incorrectly) pays twice
for the same `PaymentHash`.
Users could also fail for duplicative `PaymentClaimable` events of
the same `PaymentHash`, but doing so may result in spuriously
failing a payment if the `PaymentClaimable` event is a replay and
they never saw a corresponding `PaymentClaimed` event.
While none of this will result in spuriously thinking they've been
paid when they have not, it does result in some pretty awkward
semantics which we'd rather avoid our users having to deal with.
Instead, here, we add a new `PaymentId` which is simply an HMAC of
the HTLCs (as Channel ID, HTLC ID pairs) which were included in the
payment.
In the next commit we'll start generating `PaymentId`s for inbound
payments randomly by HMAC'ing the HTLC set of the payment. Here we
start by defining the HMAC secret for these HMACs.
This requires one small test adaptation and a full_stack_target
fuzz change because it changes the RNG consumption.
In the next commit we'll change the order of HTLCs in
`PaymentClaim[able,ed]` events. This shouldn't break anything, but
our current functional tests check that the HTLCs are provided in
the order they expect (the order they were received). Instead, here
we only validate that each claimed HTLC matches one expected path.
