BOLT 1 specifies a custom message type range for use with experimental
or application-specific messages. While a `CustomMessageHandler` can be
defined to support more than one message type, defining such a handler
requires a significant amount of boilerplate and can be error prone.
Add a crate exporting a `composite_custom_message_handler` macro for
easily composing pre-defined custom message handlers. The resulting
handler can be further composed with other custom message handlers using
the same macro.
This requires a separate crate since the macro needs to support "or"
patterns in macro_rules, which is only available in edition 2021.
https://doc.rust-lang.org/edition-guide/rust-2021/or-patterns-macro-rules.html
Otherwise, a crate defining a handler for a set of custom messages could
not easily be reused with another custom message handler. Doing so would
require explicitly duplicating the reused handlers type ids, but those
may change when the crate is updated.
It is proportion of the channel value to configure as the
`their_channel_reserve_satoshis` for both outbound and inbound channels.
It decides the minimum balance that the other node has to maintain on their
side, at all times.
To ensure no-std is honored across dependencies, add a crate depending
on lightning crates supporting no-std. This should ensure any
regressions are caught. Otherwise, cargo doesn't seem to catch some
incompatibilities (e.g., f64::log10 unavailable in core) and seemingly
across other dependencies as describe here:
https://blog.dbrgn.ch/2019/12/24/testing-for-no-std-compatibility/
Bolt 12 details the process of picking up route hints from payee
using the lightning invoice. This PR brings the changes to use
multiple route hints from payee picked from the invoice.
The route hints are processed in the following manner:-
- `get_route()` receives the hints in `last_hops`.
- Every `RouteHintHop` in `RouteHint` is processed based on
feasiblity of channel capacity and fees.
- If a `RouteHintHop` then preceeding `RouteHintHop`s are not
processed.
- A direct route is checked from `first_hops_targets` to the
first `RouteHintHop` if the respective `RouteHint` is
processed from the payee's end till the first `RouteHintHop`.
`partial_route_hint_test`, `ignores_empty_last_hops_test`,
`multi_hint_last_hops_test` and `last_hops_with_public_channel_test`
test usage of partial route hints for building optimal route,
processing empty route hint hops, complete usage of private route
hints and presence of public channels in route hints respectively.
Resolves: #945
