Add a builder for creating offers given a required description and
node_id. Other settings are optional and duplicative settings will
override previous settings for non-Vec fields.
The offer message in BOLT 12 contains a features TLV record. Add a
corresponding OfferFeatures type where the length is not included in the
serialization as it would be redundant with the record length.
Otherwise, define the features to be the same as InvoiceFeatures.
Now that the features contexts track the full set of all known
features, rather than the set of supported features, all defined
features should be listed in the context definition macro.
This adds a compile-time assertion to check that all bits for known
features are set in the context known set.
Now that the `*Features::known` constructor has been removed, there
is no reason to define feature bits as either optional required in
`features.rs` - that logic now belongs in the modules that are
responsible for the given features.
Instead, we only list all features in each context.
As we move towards specify supported/required feature bits in the
module(s) where they are supported, the global `known` feature set
constructors no longer make sense.
Here we (finally) remove the `known` constructor entirely,
modifying tests in the `features` module as required.
Historically, LDK has considered the "set of known/supported
feature bits" to be an LDK-level thing. Increasingly this doesn't
make sense - different message handlers may provide or require
different feature sets.
In a previous PR, we began the process of transitioning with
feature bits sent to peers being sourced from the attached message
handler.
This commit makes further progress by moving the concept of which
feature bits are supported by our ChannelManager into
channelmanager.rs itself, via the new `provided_*_features`
methods, rather than in features.rs via the `known_channel_features`
and `known` methods.
When ChannelMessageHandler implementations wish to return a NodeFeatures which
contain all the known flags that are relevant to channel handling, but not
gossip handling, they currently need to do so by manually constructing a
NodeFeatures with all known flags and then clearing the ones they don't want.
Instead of spreading this logic across the codebase, this consolidates such
construction into one place in features.rs.
When `ChannelMessageHandler` implementations wish to return an
`InitFeatures` which contain all the known flags that are relevant
to channel handling, but not gossip handling, they currently need
to do so by manually constructing an InitFeatures with all known
flags and then clearing the ones they dont want.
Instead of spreading this logic out across the codebase, this
consolidates such construction to one place in features.rs.
This does not, however, ever send the scid_alias feature bit for
outgoing channels, as that would cause the immediately prior
version of LDK to be unable to read channel data.
The take-self-return-Self idiom in Rust is substantially less
usable than it is in Java, where its more common. Because we have
to take self by move, it prevents using the update methods to
actually update features, something we occasionally want to do.
See, eg, the change in lightning-invoice where we previously had
to copy and re-create an entire vec of fields just to update the
features field, which is nuts.
There are a few places where this makes things a little less clean,
but the tradeoff to enable more effecient and broader uses of the
update methods seems worth it.
Note that this feature bit does absolutely nothing. We signal it
(as we already support channel type negotiation), but do not bother
to look to see if peers support it, as we don't care - we simply
look for the TLV entry and deduce if a peer supports channel type
negotiation from that.
The only behavioral change at all here is that we don't barf if a
peer sets channel type negotiation to required via the feature bit
(instead of failing the channel at open-time), but of course no
implementations do this, and likely won't for some time (if ever -
you can simply fail channels with unknown types later, and there's
no reason to refuse connections, really).
As defined in https://github.com/lightning/bolts/pull/906
An upcoming Router interface will be used for finding a Route both when
initially sending a payment and also when retrying failed payment paths.
Unify the three varieties of get_route so the interface can consist of a
single method implemented by the new `find_route` method. Give get_route
pub(crate) visibility so it can still be used in tests.
Its semantics are somewhat different from existing features,
however not enough to merit a different struct entirely.
Specifically, it only supports required features (if you send a
channel_type, the counterparty has to accept it wholesale or try
again, it cannot select only a subset of the flags) and it is
serialized differently (only appearing in TLVs).
In order to avoid significant malloc traffic, messages previously
explicitly stated their serialized length allowing for Vec
preallocation during the message serialization pipeline. This added
some amount of complexity in the serialization code, but did avoid
some realloc() calls.
Instead, here, we drop all the complexity in favor of a fixed 2KiB
buffer for all message serialization. This should not only be
simpler with a similar reduction in realloc() traffic, but also
may reduce heap fragmentation by allocating identically-sized
buffers more often.
When there are fewer known `from` feature bytes than known `to` feature
bytes, an index-out-of-bounds error can occur if the `from` features
have unknown features set in a byte past the greatest known `from`
feature byte.
This was reported by a user when trying to send a payment using the LDK
sample (specifically during route generation when translating a Features
from one context to another)
The problem was we didn't check T::KNOWN_FEATURE_MASK vec length before
indexing into it, due likely to the assumption that known feature vec
lengths are the same across contexts, when they may not be
Instead of relying on users to set an invoice's features correctly,
enforce the semantics inside InvoiceBuilder. For instance, if the user
sets a PaymentSecret then InvoiceBuilder should ensure the appropriate
feature bits are set. Thus, for this example, the TaggedField
abstraction can be retained while still ensuring BOLT 11 semantics at
the builder abstraction.
