lnd.xprv/chanacceptor/merge.go
carla 5679dde1bc
multi: add channel open parameters to channel acceptor
Add more fields to channel acceptor response so that users can have more
fine grained control over their incoming channels. With our chained
acceptor, it is possible that we get inconsistent responses from
multiple chained acceptors. We create a conjugate repsponse from all the
set fields in our various responses, but fail if we get different, non-
zero responses from our various acceptors. Separate merge functions are
used per type so that we avoid unexpected outcomes comparing interfaces
(panic on comparing types that aren't comparable), with casting used
where applicable to avoid code duplication.
2020-11-10 21:09:10 +02:00

153 lines
3.5 KiB
Go

package chanacceptor
import (
"bytes"
"fmt"
"github.com/btcsuite/btcutil"
"github.com/lightningnetwork/lnd/lnwire"
)
const (
// We use field names in our errors for more readable errors. Create
// consts for them here so that we can exactly match in our unit tests.
fieldCSV = "csv delay"
fieldHtlcLimit = "htlc limit"
fieldMinDep = "min depth"
fieldReserve = "reserve"
fieldMinIn = "min htlc in"
fieldInFlightTotal = "in flight total"
fieldUpfrontShutdown = "upfront shutdown"
)
// fieldMismatchError returns a merge error for a named field when we get two
// channel acceptor responses which have different values set.
func fieldMismatchError(name string, current, new interface{}) error {
return fmt.Errorf("multiple values set for: %v, %v and %v",
name, current, new)
}
// mergeInt64 merges two int64 values, failing if they have different non-zero
// values.
func mergeInt64(name string, current, new int64) (int64, error) {
switch {
case current == 0:
return new, nil
case new == 0:
return current, nil
case current != new:
return 0, fieldMismatchError(name, current, new)
default:
return new, nil
}
}
// mergeMillisatoshi merges two msat values, failing if they have different
// non-zero values.
func mergeMillisatoshi(name string, current,
new lnwire.MilliSatoshi) (lnwire.MilliSatoshi, error) {
switch {
case current == 0:
return new, nil
case new == 0:
return current, nil
case current != new:
return 0, fieldMismatchError(name, current, new)
default:
return new, nil
}
}
// mergeDeliveryAddress merges two delivery address values, failing if they have
// different non-zero values.
func mergeDeliveryAddress(name string, current,
new lnwire.DeliveryAddress) (lnwire.DeliveryAddress, error) {
switch {
case current == nil:
return new, nil
case new == nil:
return current, nil
case !bytes.Equal(current, new):
return nil, fieldMismatchError(name, current, new)
default:
return new, nil
}
}
// mergeResponse takes two channel accept responses, and attempts to merge their
// fields, failing if any fields conflict (are non-zero and not equal). It
// returns a new response that has all the merged fields in it.
func mergeResponse(current, new ChannelAcceptResponse) (ChannelAcceptResponse,
error) {
csv, err := mergeInt64(
fieldCSV, int64(current.CSVDelay), int64(new.CSVDelay),
)
if err != nil {
return current, err
}
current.CSVDelay = uint16(csv)
htlcLimit, err := mergeInt64(
fieldHtlcLimit, int64(current.HtlcLimit),
int64(new.HtlcLimit),
)
if err != nil {
return current, err
}
current.HtlcLimit = uint16(htlcLimit)
minDepth, err := mergeInt64(
fieldMinDep, int64(current.MinAcceptDepth),
int64(new.MinAcceptDepth),
)
if err != nil {
return current, err
}
current.MinAcceptDepth = uint16(minDepth)
reserve, err := mergeInt64(
fieldReserve, int64(current.Reserve), int64(new.Reserve),
)
if err != nil {
return current, err
}
current.Reserve = btcutil.Amount(reserve)
current.MinHtlcIn, err = mergeMillisatoshi(
fieldMinIn, current.MinHtlcIn, new.MinHtlcIn,
)
if err != nil {
return current, err
}
current.InFlightTotal, err = mergeMillisatoshi(
fieldInFlightTotal, current.InFlightTotal,
new.InFlightTotal,
)
if err != nil {
return current, err
}
current.UpfrontShutdown, err = mergeDeliveryAddress(
fieldUpfrontShutdown, current.UpfrontShutdown,
new.UpfrontShutdown,
)
if err != nil {
return current, err
}
return current, nil
}