When updating the channel routing policy, we encounter an inaccurate
precision error when calculating the routing fee. The issue stems from
the way the IEEE 754 standard works.
The solution here is to add a uint64 parameter (as mentioned in the
issue) and keep the float64 fee_rate parameter but rounding the product
of the base and fee rate.
This commit adds a new unique intercept message ID that is different for
each message sent to an RPC middleware. This will allow us to re-purpose
the existing request ID field into its original intention, which was to
have a unique ID for a full gRPC request/response pair or gRPC stream as
a whole.
To make it possible to use a remote lnrpc server as a signer for our
wallet, we need to change our main interface to sign the message instead
of the message's digest. Otherwise we'd need to alter the
lnrpc.SignMessage RPC to accept a digest instead of only the message
which has security implications.
The FundingPsbtFinalize step is a safety measure that assures the final
signed funding transaction has the same TXID as was registered during
the funding flow and was used for the commitment transactions.
This step is cumbersome to use if the whole funding process is completed
external to lnd. We allow the finalize step to be skipped for such
cases. The API user/script will need to make sure things are verified
(and possibly cleaned up) properly.
With the middleware handler in place, we now need to add a new gRPC
interceptor to the interceptor chain that will send messages to the
registered middlewares for each event that could be of interest to them.
With this commit we introduce the concept of RPC middleware: A mechanism
similar to the existing channel or HTLC interceptors but this time for
gRPC messages themselves.
An RPC middleware can register itself to the main RPC server to get
notified each time a new gRPC request comes in, a gRPC response is sent
back or a streaming RPC is connected. The middleware can
validate/inspect incoming requests and modify/overwrite outgoing
responses.
Since this also opens the door for malicious software to interfere with
lnd in a negative way, we bind everything to macaroons with custom
caveat conditions: A middleware declares upon registration which custom
caveat name it can handle. Only client requests that send a macaroon
with that custom caveat will then be given to the middleware for
inspection. The only exception is if the middleware instead registers
to use the read-only mode. In that mode it will be able to intercept
all requests/responses, even those not made with a special encumbered
macaroon. But the middleware won't be able to alter responses in the
read-only mode. Therefore requests with the default, unencumbered macaroons
can never be modified by any middleware.
The RPC DeletePayment allows deleteing single payment from its ID. When calling with `FailedHtlcsOnly` set in the request only failed HTLCs of this payment will be deleted.
This field will be examined later down the stack along with the set of
feature bits to determine if explicit channel commitment type
negotiation is possible or not.
To avoid a naming conflict with etcd, we rename our very generic
rpc.proto to lightning.proto to match the service name that's declared
within. This will break many external tutorials and possibly also our
API docs but the change needs to be done eventually.
