feat(parachain): Create struct for Approval Distribution Message (#3326)

lib/parachain/approval_distribution_message.go

@@ -0,0 +1,216 @@
+// Copyright 2021 ChainSafe Systems (ON)
+// SPDX-License-Identifier: LGPL-3.0-only
+
+package parachain
+
+import (
+	"fmt"
+
+	"github.com/ChainSafe/gossamer/lib/common"
+	"github.com/ChainSafe/gossamer/lib/crypto/sr25519"
+	"github.com/ChainSafe/gossamer/pkg/scale"
+)
+
+type AssignmentCertKindValues interface {
+	RelayVRFModulo | RelayVRFDelay
+}
+
+// AssignmentCertKind different kinds of input or criteria that can prove a validator's assignment
+// to check a particular parachain.
+type AssignmentCertKind struct {
+	inner any
+}
+
+func setAssignmentCertKind[Value AssignmentCertKindValues](mvdt *AssignmentCertKind, value Value) {
+	mvdt.inner = value
+}
+
+func (mvdt *AssignmentCertKind) SetValue(value any) (err error) {
+	switch value := value.(type) {
+	case RelayVRFModulo:
+		setAssignmentCertKind(mvdt, value)
+		return
+
+	case RelayVRFDelay:
+		setAssignmentCertKind(mvdt, value)
+		return
+
+	default:
+		return fmt.Errorf("unsupported type")
+	}
+}
+
+func (mvdt AssignmentCertKind) IndexValue() (index uint, value any, err error) {
+	switch mvdt.inner.(type) {
+	case RelayVRFModulo:
+		return 0, mvdt.inner, nil
+
+	case RelayVRFDelay:
+		return 1, mvdt.inner, nil
+
+	}
+	return 0, nil, scale.ErrUnsupportedVaryingDataTypeValue
+}
+
+func (mvdt AssignmentCertKind) Value() (value any, err error) {
+	_, value, err = mvdt.IndexValue()
+	return
+}
+
+func (mvdt AssignmentCertKind) ValueAt(index uint) (value any, err error) {
+	switch index {
+	case 0:
+		return *new(RelayVRFModulo), nil
+
+	case 1:
+		return *new(RelayVRFDelay), nil
+
+	}
+	return nil, scale.ErrUnknownVaryingDataTypeValue
+}
+
+// NewAssignmentCertKindVDT constructor for AssignmentCertKind
+func NewAssignmentCertKindVDT() AssignmentCertKind {
+	return AssignmentCertKind{}
+}
+
+// RelayVRFModulo an assignment story based on the VRF that authorized the relay-chain block where the
+// candidate was included combined with a sample number.
+type RelayVRFModulo struct {
+	// Sample the sample number used in this cert.
+	Sample uint32
+}
+
+// NewRelayVRFModulo constructor for RelayVRFModulo
+func NewRelayVRFModulo() RelayVRFModulo {
+	return RelayVRFModulo{}
+}
+
+// RelayVRFDelay an assignment story based on the VRF that authorized the relay-chain block where the
+// candidate was included combined with the index of a particular core.
+type RelayVRFDelay struct {
+	// CoreIndex the unique (during session) index of a core.
+	CoreIndex uint32
+}
+
+// NewVRFDelay constructor for RelayVRFDelay
+func NewVRFDelay() RelayVRFDelay {
+	return RelayVRFDelay{}
+}
+
+// VrfSignature represents VRF signature, which itself consists of a VRF pre-output and DLEQ proof
+type VrfSignature struct {
+	// Output VRF output
+	Output [sr25519.VRFOutputLength]byte `scale:"1"`
+	// Proof VRF proof
+	Proof [sr25519.VRFProofLength]byte `scale:"2"`
+}
+
+// AssignmentCert is a certification of assignment
+type AssignmentCert struct {
+	// Kind the criterion which is claimed to be met by this cert.
+	Kind AssignmentCertKind `scale:"1"`
+	// Vrf the VRF signature showing the criterion is met.
+	Vrf VrfSignature `scale:"2"`
+}
+
+// IndirectAssignmentCert is an assignment criterion which refers to the candidate under which the assignment is
+// relevant by block hash.
+type IndirectAssignmentCert struct {
+	// BlockHash a block hash where the canidate appears.
+	BlockHash common.Hash `scale:"1"`
+	// Validator the validator index.
+	Validator ValidatorIndex `scale:"2"`
+	// Cert the cert itself.
+	Cert AssignmentCert `scale:"3"`
+}
+
+// CandidateIndex represents the index of the candidate in the list of candidates fully included as-of the block.
+type CandidateIndex uint32
+
+// Assignment holds indirect assignment cert and candidate index
+type Assignment struct {
+	IndirectAssignmentCert IndirectAssignmentCert `scale:"1"`
+	CandidateIndex         CandidateIndex         `scale:"2"`
+}
+
+// Assignments for candidates in recent, unfinalized blocks.
+type Assignments []Assignment
+
+// IndirectSignedApprovalVote represents a signed approval vote which references the candidate indirectly via the block.
+type IndirectSignedApprovalVote struct {
+	// BlockHash a block hash where the candidate appears.
+	BlockHash common.Hash `scale:"1"`
+	// CandidateIndex the index of the candidate in the list of candidates fully included as-of the block.
+	CandidateIndex CandidateIndex `scale:"2"`
+	// ValidatorIndex the validator index.
+	ValidatorIndex ValidatorIndex `scale:"3"`
+	// Signature the signature of the validator.
+	Signature ValidatorSignature `scale:"4"`
+}
+
+// Approvals for candidates in some recent, unfinalized block.
+type Approvals []IndirectSignedApprovalVote
+
+// ApprovalDistributionMessage network messages used by approval distribution subsystem.
+type ApprovalDistributionMessageValues interface {
+	Assignments | Approvals
+}
+
+// ApprovalDistributionMessage network messages used by approval distribution subsystem.
+type ApprovalDistributionMessage struct {
+	inner any
+}
+
+func setApprovalDistributionMessage[Value ApprovalDistributionMessageValues](mvdt *ApprovalDistributionMessage, value Value) {
+	mvdt.inner = value
+}
+
+func (mvdt *ApprovalDistributionMessage) SetValue(value any) (err error) {
+	switch value := value.(type) {
+	case Assignments:
+		setApprovalDistributionMessage(mvdt, value)
+		return
+
+	case Approvals:
+		setApprovalDistributionMessage(mvdt, value)
+		return
+
+	default:
+		return fmt.Errorf("unsupported type")
+	}
+}
+
+func (mvdt ApprovalDistributionMessage) IndexValue() (index uint, value any, err error) {
+	switch mvdt.inner.(type) {
+	case Assignments:
+		return 0, mvdt.inner, nil
+
+	case Approvals:
+		return 1, mvdt.inner, nil
+
+	}
+	return 0, nil, scale.ErrUnsupportedVaryingDataTypeValue
+}
+
+func (mvdt ApprovalDistributionMessage) Value() (value any, err error) {
+	_, value, err = mvdt.IndexValue()
+	return
+}
+
+func (mvdt ApprovalDistributionMessage) ValueAt(index uint) (value any, err error) {
+	switch index {
+	case 0:
+		return *new(Assignments), nil
+
+	case 1:
+		return *new(Approvals), nil
+
+	}
+	return nil, scale.ErrUnknownVaryingDataTypeValue
+}
+
+// NewApprovalDistributionMessageVDT ruturns a new ApprovalDistributionMessage VaryingDataType
+func NewApprovalDistributionMessageVDT() ApprovalDistributionMessage {
+	return ApprovalDistributionMessage{}
+}