The getroute -> getroutes migrations dropped the legacy
exclude=[self_id] argument in the two probing modules whose askrene
source is a remote node. Nothing replaced it: askrene's gossmap
includes our public channels like anyone else's, and an empty layers
array applies no exclusions. Consequences:
- Dowser capacity probes could route part of the candidate->patron
flow through our own node, counting our own liquidity toward a
candidate's capacity -- retaining weak candidates and over-sizing
the channels ChannelCreator opens.
- ActiveProber probes could pick path[0] = peer->us, degenerating
into a circular us->peer->us payment that measures our own shared
channel's peer->us balance instead of the peer's outward reach,
with SendpayResultMonitor crediting the peer destination_reached
for it.
Introduce AskreneLayer::self_layer_name ("clboss-self"): a tiny
persistent layer whose only content is our node in disabled_nodes,
maintained by AskreneLayer::ensure_self_layer() (idempotent create,
deduped disable). Both modules resolve it before probing and name it
in their getroutes layers array; when askrene is unavailable they
probe without it, as before. Kept separate from the clboss layer --
whose disabled_nodes also carries self -- because that layer's
learned constraints would bias what the probes measure.
CLN v26.06 deprecates getroute in favor of askrene's getroutes.
Replace the Dowser's getroute+listchannels loop (up to ~40 RPC
round-trips) with a single getroutes call and let askrene's
min-cost-flow solver enumerate multi-path capacity directly. Response
parsing follows the getroutes schema; 205/206 (no route / too
expensive) maps to zero capacity.
Size the probe to the caller's threshold. The Dowser is a flow
estimator: callers compare the dowsed flow against a channel size (the
janitor and preinvestigator min-channel acceptance test, the channel
creator's sizing). A fixed probe amount caps the estimate, so any
threshold at or above that cap rejects every candidate regardless of
real capacity. RequestDowser now carries a min_amount; callers that
test against a channel size set it, and the probe runs at
min_amount / reserve_factor so a full-flow result clears the threshold
for any configured channel size. The channel creator dowses at
max-channel so new channels size toward the operator ceiling instead
of being pinned at the min-channel floor. The manual clboss-dowser
command keeps the fixed default probe.
Channel directions can be individually active or inactive, which affects
routing directions.
Thus, a dowsing request in on direction may have a different result in
the opposite direction.
Existing clients of the `Dowser` assume the first argument is the source
(proposal) and the second argument is the destination (patron), but the
`Dowser` used the first argument as the destination instead.
This also flips the `Dowser` direction.
