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Merge pull request #924 from statechannels/cmk.n-hop-defund
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Generlise virtualdefund to be n-hop
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@NiloCK
NiloCK authored Oct 6, 2022
2 parents a7dd002 + fbd1e36 commit 4f962d8
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Showing 3 changed files with 91 additions and 72 deletions.
2 changes: 1 addition & 1 deletion protocols/virtualdefund/serde.go
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Original file line number Diff line number Diff line change
Expand Up @@ -18,7 +18,7 @@ type jsonObjective struct {
VFixed state.FixedPart
InitialOutcome outcome.SingleAssetExit
FinalOutcome outcome.SingleAssetExit
Signatures [3]state.Signature
Signatures []state.Signature

ToMyLeft []byte
ToMyRight []byte
Expand Down
159 changes: 89 additions & 70 deletions protocols/virtualdefund/virtualdefund.go
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Original file line number Diff line number Diff line change
Expand Up @@ -52,18 +52,20 @@ type Objective struct {
// VFixed is the fixed channel information for the virtual channel
VFixed state.FixedPart

// Signatures are the signatures for the final virtual state from each participant
// Signatures are ordered by participant order: Signatures[0] is Alice's signature, Signatures[1] is Irene's signature, Signatures[2] is Bob's signature
// Signatures gets updated as participants sign and send states to each other.
Signatures [3]state.Signature
// Signatures are the signatures for the final virtual state from each participant.
//
// Signatures are ordered by participant order: Signatures[0] is Alice's signature,
// Signatures[last] is Bob's signature, Signatures[1,...,n] are the intermediaries'
// signatures.
Signatures []state.Signature

ToMyLeft *consensus_channel.ConsensusChannel
ToMyRight *consensus_channel.ConsensusChannel

// MyRole is the index of the participant in the participants list
// 0 is Alice
// 1 is Irene
// 2 is Bob
// 1...n is Irene, Ivan, ... (the n intermediaries)
// n+1 is Bob
MyRole uint
}

Expand Down Expand Up @@ -98,42 +100,56 @@ func NewObjective(request ObjectiveRequest,

initialOutcome := V.PostFundState().Outcome[0]

// This logic assumes a single hop virtual channel.
// Currently this is the only type of virtual channel supported.
alice := V.Participants[0]
intermediary := V.Participants[1]
bob := V.Participants[2]
bob := V.Participants[len(V.Participants)-1]

var toMyLeft, toMyRight *consensus_channel.ConsensusChannel
var leftLedger, rightLedger *consensus_channel.ConsensusChannel
var ok bool

switch myAddress {
case alice:
toMyRight, ok = getConsensusChannel(intermediary)
if !ok {
return Objective{}, fmt.Errorf("could not find a ledger channel between %v and %v", alice, intermediary)
}
case intermediary:
toMyLeft, ok = getConsensusChannel(alice)
if myAddress == alice {
rightOfAlice := V.Participants[1]
rightLedger, ok = getConsensusChannel(rightOfAlice)
if !ok {
return Objective{}, fmt.Errorf("could not find a ledger channel between %v and %v", alice, intermediary)
return Objective{}, fmt.Errorf("could not find a ledger channel between %v and %v", alice, rightOfAlice)
}
toMyRight, ok = getConsensusChannel(bob)
} else if myAddress == bob {
leftOfBob := V.Participants[len(V.Participants)-2]
leftLedger, ok = getConsensusChannel(leftOfBob)
if !ok {
return Objective{}, fmt.Errorf("could not find a ledger channel between %v and %v", intermediary, bob)
return Objective{}, fmt.Errorf("could not find a ledger channel between %v and %v", leftOfBob, bob)
}
case bob:
toMyLeft, ok = getConsensusChannel(intermediary)
if !ok {
return Objective{}, fmt.Errorf("could not find a ledger channel between %v and %v", intermediary, bob)
} else {
intermediaries := V.Participants[1 : len(V.Participants)-1]
foundMyself := false

for i, intermediary := range intermediaries {
if myAddress == intermediary {
foundMyself = true
// I am intermediary `i` and participant `p`
p := i + 1 // participants[p] === intermediaries[i]

leftOfMe := V.Participants[p-1]
rightOfMe := V.Participants[p+1]

leftLedger, ok = getConsensusChannel(leftOfMe)
if !ok {
return Objective{}, fmt.Errorf("could not find a ledger channel between %v and %v", leftOfMe, myAddress)
}
rightLedger, ok = getConsensusChannel(bob)
if !ok {
return Objective{}, fmt.Errorf("could not find a ledger channel between %v and %v", myAddress, rightOfMe)
}

break
}
}
default:
return Objective{}, fmt.Errorf("client address not found in an expected participant index")

if !foundMyself {
return Objective{}, fmt.Errorf("client address not found in an expected participant index")
}
}

if largestPaymentAmount == nil {

largestPaymentAmount = big.NewInt(0)
}

Expand All @@ -154,10 +170,10 @@ func NewObjective(request ObjectiveRequest,
FinalOutcome: finalOutcome,
MinimumPaymentAmount: largestPaymentAmount,
VFixed: V.FixedPart,
Signatures: [3]state.Signature{},
Signatures: make([]state.Signature, len(V.FixedPart.Participants)),
MyRole: V.MyIndex,
ToMyLeft: toMyLeft,
ToMyRight: toMyRight,
ToMyLeft: leftLedger,
ToMyRight: rightLedger,
}, nil
}

Expand Down Expand Up @@ -250,9 +266,8 @@ func (o *Objective) finalState() state.State {

// Id returns the objective id.
func (o *Objective) Id() protocols.ObjectiveId {
vId := o.VFixed.ChannelId() //TODO: Handle error
return protocols.ObjectiveId(ObjectivePrefix + vId.String())

id := o.VId().String()
return protocols.ObjectiveId(ObjectivePrefix + id)
}

// Approve returns an approved copy of the objective.
Expand Down Expand Up @@ -280,27 +295,26 @@ func (o *Objective) Reject() (protocols.Objective, protocols.SideEffects) {

// OwnsChannel returns the channel that the objective is funding.
func (o *Objective) OwnsChannel() types.Destination {
vId := o.VFixed.ChannelId()
return vId
return o.VId()
}

// GetStatus returns the status of the objective.
func (o *Objective) GetStatus() protocols.ObjectiveStatus {
return o.Status
}

// Relable returns related channels that need to be stored along with the objective.
// Related returns channels that need to be stored along with the objective.
func (o *Objective) Related() []protocols.Storable {
relatable := []protocols.Storable{}
related := []protocols.Storable{}

if o.ToMyLeft != nil {
relatable = append(relatable, o.ToMyLeft)
related = append(related, o.ToMyLeft)
}

if o.ToMyRight != nil {
relatable = append(relatable, o.ToMyRight)
related = append(related, o.ToMyRight)
}
return relatable
return related
}

// Clone returns a deep copy of the receiver.
Expand All @@ -315,9 +329,9 @@ func (o *Objective) clone() Objective {
if o.MinimumPaymentAmount != nil {
clone.MinimumPaymentAmount = big.NewInt(0).Set(o.MinimumPaymentAmount)
}
clone.Signatures = [3]state.Signature{}
for i, s := range o.Signatures {
clone.Signatures[i] = state.CloneSignature(s)
clone.Signatures = []state.Signature{}
for _, sig := range o.Signatures {
clone.Signatures = append(clone.Signatures, state.CloneSignature(sig))
}
clone.MyRole = o.MyRole

Expand Down Expand Up @@ -347,7 +361,7 @@ func (o *Objective) hasFinalStateFromAlice() bool {
return !o.FinalOutcome.Equal(outcome.SingleAssetExit{})
}

// Crank inspects the extended state and declares a list of Effects to be executed
// Crank inspects the extended state and declares a list of Effects to be executed.
func (o *Objective) Crank(secretKey *[]byte) (protocols.Objective, protocols.SideEffects, protocols.WaitingFor, error) {
updated := o.clone()
sideEffects := protocols.SideEffects{}
Expand Down Expand Up @@ -388,23 +402,23 @@ func (o *Objective) Crank(secretKey *[]byte) (protocols.Objective, protocols.Sid
return &updated, sideEffects, WaitingForSignedFinal, nil
}

if !updated.isAlice() && !updated.isLeftDefunded() {
if !updated.isAlice() && !updated.leftHasDefunded() {
ledgerSideEffects, err := updated.updateLedgerToRemoveGuarantee(updated.ToMyLeft, secretKey)
if err != nil {
return o, protocols.SideEffects{}, WaitingForNothing, fmt.Errorf("error updating ledger funding: %w", err)
}
sideEffects.Merge(ledgerSideEffects)
}

if !updated.isBob() && !updated.isRightDefunded() {
if !updated.isBob() && !updated.rightHasDefunded() {
ledgerSideEffects, err := updated.updateLedgerToRemoveGuarantee(updated.ToMyRight, secretKey)
if err != nil {
return o, protocols.SideEffects{}, WaitingForNothing, fmt.Errorf("error updating ledger funding: %w", err)
}
sideEffects.Merge(ledgerSideEffects)
}

if fullyDefunded := updated.isLeftDefunded() && updated.isRightDefunded(); !fullyDefunded {
if fullyDefunded := updated.leftHasDefunded() && updated.rightHasDefunded(); !fullyDefunded {
return &updated, sideEffects, WaitingForCompleteLedgerDefunding, nil
}

Expand All @@ -414,8 +428,12 @@ func (o *Objective) Crank(secretKey *[]byte) (protocols.Objective, protocols.Sid

}

// fullySigned returns whether we have a signature from every partciapant
// fullySigned returns whether we have a signature from every partciapant.
func (o *Objective) fullySigned() bool {
if len(o.Signatures) != len(o.VFixed.Participants) {
return false
}

for _, sig := range o.Signatures {
if isZero(sig) {
return false
Expand All @@ -424,14 +442,14 @@ func (o *Objective) fullySigned() bool {
return true
}

// isAlice returns true if the receiver represents participant 0 in the virtualdefund protocol
// isAlice returns true if the receiver represents participant 0 in the virtualdefund protocol.
func (o *Objective) isAlice() bool {
return o.MyRole == 0
}

// isBob returns true if the receiver represents participant 2 in the virtualdefund protocol
// isBob returns true if the receiver represents the last participant in the virtualdefund protocol.
func (o *Objective) isBob() bool {
return o.MyRole == 2
return int(o.MyRole) == len(o.VFixed.Participants)-1
}

// ledgerProposal generates a ledger proposal to remove the guarantee for V for ledger
Expand Down Expand Up @@ -487,25 +505,24 @@ func (o *Objective) updateLedgerToRemoveGuarantee(ledger *consensus_channel.Cons

// VId returns the channel id of the virtual channel.
func (o *Objective) VId() types.Destination {
vId := o.VFixed.ChannelId() // TODO Deal with error

return vId
return o.VFixed.ChannelId()
}

// signedBy returns whether we have a valid signature for the given participant
func (o *Objective) signedBy(participant uint) bool {
return !isZero(o.Signatures[participant])
}

// signedByMe returns whether the current participant has signed the final state
// signedByMe returns whether the current participant has signed the final state.
func (o *Objective) signedByMe() bool {
return o.signedBy(o.MyRole)

}

// isRightDefunded returns whether the ledger channel ToMyRight has been defunded
// If ToMyRight==nil then we return true
func (o *Objective) isRightDefunded() bool {
// rightHasDefunded returns whether the ledger channel ToMyRight has removed
// its funding for the target channel.
//
// If ToMyRight==nil then we return true.
func (o *Objective) rightHasDefunded() bool {
if o.ToMyRight == nil {
return true
}
Expand All @@ -514,9 +531,11 @@ func (o *Objective) isRightDefunded() bool {
return !included
}

// isLeftDefunded returns whether the ledger channel ToMyLeft has been defunded
// If ToMyLeft==nil then we return true
func (o *Objective) isLeftDefunded() bool {
// leftHasDefunded returns whether the ledger channel ToMyLeft has removed
// its funding for the target channel.
//
// If ToMyLeft==nil then we return true.
func (o *Objective) leftHasDefunded() bool {
if o.ToMyLeft == nil {
return true
}
Expand All @@ -525,10 +544,10 @@ func (o *Objective) isLeftDefunded() bool {
return !included
}

// validateSignature returns whether the given signature is valid for the given participant
// If a signature is invalid an error will be returned containing the reason
// validateSignature returns whether the given signature is valid for the given participant.
// If a signature is invalid an error will be returned containing the reason.
func (o *Objective) validateSignature(sig state.Signature, participantIndex uint) (bool, error) {
if participantIndex > 2 {
if participantIndex >= uint(len(o.VFixed.Participants)) {
return false, fmt.Errorf("participant index %d is out of bounds", participantIndex)
}

Expand All @@ -538,7 +557,7 @@ func (o *Objective) validateSignature(sig state.Signature, participantIndex uint
return false, fmt.Errorf("failed to recover signer from signature: %w", err)
}
if signer != o.VFixed.Participants[participantIndex] {
return false, fmt.Errorf("signature is for %s, expected signature from %s ", signer, o.VFixed.Participants[participantIndex])
return false, fmt.Errorf("signature is from %s, but expected signature from %s ", signer, o.VFixed.Participants[participantIndex])
}
return true, nil
}
Expand Down Expand Up @@ -588,7 +607,7 @@ func (o *Objective) Update(op protocols.ObjectivePayload) (protocols.Objective,
}

incomingSignatures := ss.Signatures()
for i := uint(0); i < 3; i++ {
for i := range o.VFixed.Participants {
existingSig := o.Signatures[i]
incomingSig := incomingSignatures[i]

Expand All @@ -605,7 +624,7 @@ func (o *Objective) Update(op protocols.ObjectivePayload) (protocols.Objective,
}
}
// Otherwise we validate the incoming signature and update our signatures
isValid, err := updated.validateSignature(incomingSig, i)
isValid, err := updated.validateSignature(incomingSig, uint(i))
if isValid {
// Update the signature
updated.Signatures[i] = incomingSig
Expand Down
2 changes: 1 addition & 1 deletion protocols/virtualdefund/virtualdefund_test.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -202,7 +202,7 @@ func TestConstructObjectiveFromState(t *testing.T) {
InitialOutcome: data.vInitial.Outcome[0],
FinalOutcome: data.vFinal.Outcome[0],
VFixed: data.vFinal.FixedPart(),
Signatures: [3]state.Signature{},
Signatures: make([]state.Signature, 3),
ToMyLeft: left,
ToMyRight: right,
MinimumPaymentAmount: big.NewInt(int64(data.paid)),
Expand Down

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