This commit prepares for more manipulation of custom records. A list of
tlv.Record types is more difficult to use than the more basic
map[uint64][]byte.
Furthermore fields and variables are renamed to make them more
consistent.
A unified policy differs between local channels and other channels on
the network. There is more information available for local channels and
this is used in the unified policy.
Previously we used the pathfinding source pubkey to determine whether to
apply the local channel logic or not. If queryroutes is executed with a
source node that isn't the self node, this wouldn't work.
When the (virtual) payment attempt cost is set to zero, probabilities
are no longer a factor in determining the best route. In case of routes
with equal costs, we'd just go with the first one found. This commit
refines this behavior by picking the route with the highest probability.
So even though probability doesn't affect the route cost, it is still
used as a tie breaker.
This prepares for routing to self. When checking the condition at the
start, the loop would terminate immediately because the source is equal
to the target.
This commit modifies the FetchPayment method to return MPPayment structs
converted from the legacy on-disk format. This allows us to attach the
HTLCs to the events given to clients subscribing to the outcome of an
HTLC.
This commit also bubbles up to the routerrpc/router_server, by
populating HTLCAttempts in the response and extracting the legacy route
field from the HTLCAttempts.
Previously we used the a priori probability also for our own untried
channels. This led to local channels that had seen a success already
being prioritized over untried local channels. In some cases, depending
on the configured payment attempt cost, this could lead to the payment
taking a two hop route while a direct payment was also possible.
An InvalidOnionPayload implies that the onion was successfully received
by the reporting node, but that they were unable to extract the
contents. Since we assume our own behavior is correct, this mostly
likely poins to an error in the reporter's implementation or that we
sent an unknown required type. Therefore we only penalize that single
hop, and consider the failure terminal if the receiver reported it.
