lnd.xprv/watchtower/blob/type.go

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package blob
import (
"fmt"
"strings"
)
// Flag represents a specify option that can be present in a Type.
type Flag uint16
const (
// FlagReward signals that the justice transaction should contain an
// additional output for itself. Signatures sent by the client should
// include the reward script negotiated during session creation. Without
// the flag, there is only one output sweeping clients funds back to
// them solely.
FlagReward Flag = 1
// FlagCommitOutputs signals that the blob contains the information
// required to sweep commitment outputs.
FlagCommitOutputs Flag = 1 << 1
// FlagAnchorChannel signals that this blob is meant to spend an anchor
// channel, and therefore must expect a P2WSH-style to-remote output if
// one exists.
FlagAnchorChannel Flag = 1 << 2
)
// Type returns a Type consisting solely of this flag enabled.
func (f Flag) Type() Type {
return Type(f)
}
// String returns the name of the flag.
func (f Flag) String() string {
switch f {
case FlagReward:
return "FlagReward"
case FlagCommitOutputs:
return "FlagCommitOutputs"
case FlagAnchorChannel:
return "FlagAnchorChannel"
default:
return "FlagUnknown"
}
}
// Type is a bit vector composed of Flags that govern various aspects of
// reconstructing the justice transaction from an encrypted blob. The flags can
// be used to signal behaviors such as which inputs are being swept, which
// outputs should be added to the justice transaction, or modify serialization
// of the blob itself.
type Type uint16
const (
// TypeAltruistCommit sweeps only commitment outputs to a sweep address
// controlled by the user, and does not give the tower a reward.
TypeAltruistCommit = Type(FlagCommitOutputs)
// TypeAltruistAnchorCommit sweeps only commitment outputs from an
// anchor commitment to a sweep address controlled by the user, and does
// not give the tower a reward.
TypeAltruistAnchorCommit = Type(FlagCommitOutputs | FlagAnchorChannel)
// TypeRewardCommit sweeps only commitment outputs to a sweep address
// controlled by the user, and pays a negotiated reward to the tower.
TypeRewardCommit = Type(FlagCommitOutputs | FlagReward)
)
// Has returns true if the Type has the passed flag enabled.
func (t Type) Has(flag Flag) bool {
return Flag(t)&flag == flag
}
// TypeFromFlags creates a single Type from an arbitrary list of flags.
func TypeFromFlags(flags ...Flag) Type {
var typ Type
for _, flag := range flags {
typ |= Type(flag)
}
return typ
}
// IsAnchorChannel returns true if the blob type is for an anchor channel.
func (t Type) IsAnchorChannel() bool {
return t.Has(FlagAnchorChannel)
}
// knownFlags maps the supported flags to their name.
var knownFlags = map[Flag]struct{}{
FlagReward: {},
FlagCommitOutputs: {},
FlagAnchorChannel: {},
}
// String returns a human readable description of a Type.
func (t Type) String() string {
var (
hrPieces []string
hasUnknownFlags bool
)
// Iterate through the possible flags from highest to lowest. This will
// ensure that the human readable names will be in the same order as the
// bits (left to right) if the type were to be printed in big-endian
// byte order.
for f := Flag(1 << 15); f != 0; f >>= 1 {
// If this flag is known, we'll add a human-readable name or its
// inverse depending on whether the type has this flag set.
if _, ok := knownFlags[f]; ok {
if t.Has(f) {
hrPieces = append(hrPieces, f.String())
} else {
hrPieces = append(hrPieces, "No-"+f.String())
}
} else {
// Make note of any unknown flags that this type has
// set. If any are present, we'll prepend the bit-wise
// representation of the type in the final string.
if t.Has(f) {
hasUnknownFlags = true
}
}
}
// If there were no unknown flags, we'll simply return the list of human
// readable pieces.
if !hasUnknownFlags {
return fmt.Sprintf("[%s]", strings.Join(hrPieces, "|"))
}
// Otherwise, we'll prepend the bit-wise representation to the human
// readable names.
return fmt.Sprintf("%016b[%s]", t, strings.Join(hrPieces, "|"))
}
// supportedTypes is the set of all configurations known to be supported by the
// package.
var supportedTypes = map[Type]struct{}{
TypeAltruistCommit: {},
TypeRewardCommit: {},
TypeAltruistAnchorCommit: {},
}
// IsSupportedType returns true if the given type is supported by the package.
func IsSupportedType(blobType Type) bool {
_, ok := supportedTypes[blobType]
return ok
}
// SupportedTypes returns a list of all supported blob types.
func SupportedTypes() []Type {
supported := make([]Type, 0, len(supportedTypes))
for t := range supportedTypes {
supported = append(supported, t)
}
return supported
}