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Documentation

Overview

Package header contains all services related to generating, requesting, syncing and storing ExtendedHeaders.

An ExtendedHeader is similar to a regular block header from celestia-core, but "extended" by adding the DataAvailabilityHeader (DAH), ValidatorSet and Commit in order to allow for light and full nodes to reconstruct block data by referencing the DAH.

ExtendedHeaders are generated by bridge nodes that listen to the celestia-core network for blocks, validate and extend the block data in order to generate the DAH, and request both the ValidatorSet and Commit for that block height from the celestia-core network. Bridge nodes then package that data up into an ExtendedHeader and broadcast it to the 'header-sub' GossipSub topic (HeaderSub). All nodes subscribed to HeaderSub will receive and validate the ExtendedHeader, and store it, making it available to all other dependent services (such as the DataAvailabilitySampler, or DASer) to access.

There are 5 main components in the header package:

1. core.Listener listens for new blocks from the celestia-core network (run by bridge nodes only), extends them, generates a new ExtendedHeader, and publishes it to the HeaderSub.
2. p2p.Subscriber listens for new ExtendedHeaders from the Celestia Data Availability (DA) network (via the HeaderSub)
3. p2p.Exchange or core.Exchange request ExtendedHeaders from other celestia DA nodes (default for full and light nodes) or from a celestia-core node connection (bridge nodes only)
4. Syncer manages syncing of past and recent ExtendedHeaders from either the DA network or a celestia-core connection (bridge nodes only).
5. Store manages storing ExtendedHeaders and making them available for access by other dependent services.

For bridge nodes, the general flow of the header Service is as follows:

1. core.Listener listens for new blocks from the celestia-core connection
2. core.Listener validates the block and generates the ExtendedHeader, simultaneously storing the extended block shares to disk
3. core.Listener publishes the new ExtendedHeader to HeaderSub, notifying all subscribed peers of the new ExtendedHeader
4. Syncer is already subscribed to the HeaderSub, so it receives new ExtendedHeaders locally from the core.Listener and stores them to disk via Store. - If the celestia-core connection is started simultaneously with the bridge node, then the celestia-core connection will handle the syncing component, piping every synced block to the core.Listener - If the celestia-core connection is already synced to the network, the Syncer handles requesting past headers up to the network head from the celestia-core connection (using core.Exchange rather than p2p.Exchange).

For full and light nodes, the general flow of the header Service is as follows:

1. Syncer listens for new ExtendedHeaders from HeaderSub
2. If there is a gap between the local head of chain and the new, validated network head, the Syncer kicks off a sync routine to request all ExtendedHeaders between local head and network head.
3. While the Syncer requests headers between the local head and network head in batches, it appends them to the subjective chain via Store with the last batched header as the new local head.

Index

• Variables
• func ExtendedHeaderToProto(eh *ExtendedHeader) (*header_pb.ExtendedHeader, error)
• func MarshalExtendedHeader(in *ExtendedHeader) (_ []byte, err error)
• func MsgID(pmsg *pb.Message) string
• type ConstructFn
• type ExtendedHeader
  • func MakeExtendedHeader(h *core.Header, comm *core.Commit, vals *core.ValidatorSet, ...) (*ExtendedHeader, error)
  • func ProtoToExtendedHeader(pb *header_pb.ExtendedHeader) (*ExtendedHeader, error)
  • func UnmarshalExtendedHeader(data []byte) (*ExtendedHeader, error)
  • func (eh *ExtendedHeader) ChainID() string
  • func (eh *ExtendedHeader) Equals(header *ExtendedHeader) bool
  • func (eh *ExtendedHeader) Hash() libhead.Hash
  • func (eh *ExtendedHeader) Height() uint64
  • func (eh *ExtendedHeader) IsZero() bool
  • func (eh *ExtendedHeader) LastHeader() libhead.Hash
  • func (eh *ExtendedHeader) MarshalBinary() ([]byte, error)
  • func (eh *ExtendedHeader) MarshalJSON() ([]byte, error)
  • func (eh *ExtendedHeader) New() *ExtendedHeader
  • func (eh *ExtendedHeader) Time() time.Time
  • func (eh *ExtendedHeader) UnmarshalBinary(data []byte) error
  • func (eh *ExtendedHeader) UnmarshalJSON(data []byte) error
  • func (eh *ExtendedHeader) Validate() error
  • func (eh *ExtendedHeader) Verify(untrst *ExtendedHeader) error
• type RawHeader

Variables

var (
	ErrValidatorHashMismatch           = errors.New("validator hash mismatch")
	ErrLastHeaderHashMismatch          = errors.New("last header hash mismatch")
	ErrVerifyCommitLightTrustingFailed = errors.New("commit light trusting verification failed")
)

Functions

func ExtendedHeaderToProto

func ExtendedHeaderToProto(eh *ExtendedHeader) (*header_pb.ExtendedHeader, error)

func MarshalExtendedHeader

func MarshalExtendedHeader(in *ExtendedHeader) (_ []byte, err error)

MarshalExtendedHeader serializes given ExtendedHeader to bytes using protobuf. Paired with UnmarshalExtendedHeader.

func MsgID

func MsgID(pmsg *pb.Message) string

msgID computes an id for a pubsub message TODO(@Wondertan): This cause additional allocations per each recvd message in the topic

Find a way to avoid those.

Types

type ConstructFn

type ConstructFn = func(
	*core.Header,
	*core.Commit,
	*core.ValidatorSet,
	*rsmt2d.ExtendedDataSquare,
) (*ExtendedHeader, error)

ConstructFn aliases a function that creates an ExtendedHeader.

type ExtendedHeader

type ExtendedHeader struct {
	RawHeader    `json:"header"`
	Commit       *core.Commit       `json:"commit"`
	ValidatorSet *core.ValidatorSet `json:"validator_set"`
	DAH          *share.Root        `json:"dah"`
}

ExtendedHeader represents a wrapped "raw" header that includes information necessary for Celestia Nodes to be notified of new block headers and perform Data Availability Sampling.

func MakeExtendedHeader

func MakeExtendedHeader(
	h *core.Header,
	comm *core.Commit,
	vals *core.ValidatorSet,
	eds *rsmt2d.ExtendedDataSquare,
) (*ExtendedHeader, error)

MakeExtendedHeader assembles new ExtendedHeader.

func ProtoToExtendedHeader

func ProtoToExtendedHeader(pb *header_pb.ExtendedHeader) (*ExtendedHeader, error)

func UnmarshalExtendedHeader

func UnmarshalExtendedHeader(data []byte) (*ExtendedHeader, error)

UnmarshalExtendedHeader deserializes given data into a new ExtendedHeader using protobuf. Paired with MarshalExtendedHeader.

func (*ExtendedHeader) ChainID

func (eh *ExtendedHeader) ChainID() string

func (*ExtendedHeader) Equals

func (eh *ExtendedHeader) Equals(header *ExtendedHeader) bool

Equals returns whether the hash and height of the given header match.

func (*ExtendedHeader) Hash

func (eh *ExtendedHeader) Hash() libhead.Hash

Hash returns Hash of the wrapped RawHeader. NOTE: It purposely overrides Hash method of RawHeader to get it directly from Commit without recomputing.

func (*ExtendedHeader) Height

func (eh *ExtendedHeader) Height() uint64

func (*ExtendedHeader) IsZero

func (eh *ExtendedHeader) IsZero() bool

func (*ExtendedHeader) LastHeader

func (eh *ExtendedHeader) LastHeader() libhead.Hash

LastHeader returns the Hash of the last wrapped RawHeader.

func (*ExtendedHeader) MarshalBinary

func (eh *ExtendedHeader) MarshalBinary() ([]byte, error)

MarshalBinary marshals ExtendedHeader to binary.

func (*ExtendedHeader) MarshalJSON

func (eh *ExtendedHeader) MarshalJSON() ([]byte, error)

MarshalJSON marshals an ExtendedHeader to JSON. The ValidatorSet is wrapped with amino encoding, to be able to unmarshal the crypto.PubKey type back from JSON.

func (*ExtendedHeader) New

func (eh *ExtendedHeader) New() *ExtendedHeader

func (*ExtendedHeader) Time

func (eh *ExtendedHeader) Time() time.Time

func (*ExtendedHeader) UnmarshalBinary

func (eh *ExtendedHeader) UnmarshalBinary(data []byte) error

UnmarshalBinary unmarshals ExtendedHeader from binary.

func (*ExtendedHeader) UnmarshalJSON

func (eh *ExtendedHeader) UnmarshalJSON(data []byte) error

UnmarshalJSON unmarshals an ExtendedHeader from JSON. The ValidatorSet is wrapped with amino encoding, to be able to unmarshal the crypto.PubKey type back from JSON.

func (*ExtendedHeader) Validate

func (eh *ExtendedHeader) Validate() error

Validate performs *basic* validation to check for missed/incorrect fields.

func (*ExtendedHeader) Verify

func (eh *ExtendedHeader) Verify(untrst *ExtendedHeader) error

Verify validates given untrusted Header against trusted ExtendedHeader.

type RawHeader

type RawHeader = core.Header

RawHeader is an alias to core.Header. It is "raw" because it is not yet wrapped to include the DataAvailabilityHeader.