consensus.gno

 1package ics23_mpt
 2
 3import (
 4	"bytes"
 5	"encoding/binary"
 6	"errors"
 7
 8	"gno.land/p/onbloc/verifier/evm/storage"
 9)
10
11var (
12	ErrConsensusStateTooShort = errors.New("ics23mpt: l2 consensus state too short")
13	ErrInvalidCommitmentKey   = errors.New("ics23mpt: invalid commitment key")
14)
15
16// ExtractConsensusState parses the L2 consensus state bytes into a
17// ConsensusState using the byte offsets recorded in this client state. The
18// state-lens client trusts the counterparty's opaque L2 consensus blob and
19// reads timestamp / state root / storage root from fixed offsets.
20func (cs ClientState) ExtractConsensusState(data []byte) (ConsensusState, error) {
21	timestamp, err := extractUint64(data, int(cs.TimestampOffset))
22	if err != nil {
23		return ConsensusState{}, err
24	}
25
26	stateRoot, err := extractBytes32(data, int(cs.StateRootOffset))
27	if err != nil {
28		return ConsensusState{}, err
29	}
30
31	storageRoot, err := extractBytes32(data, int(cs.StorageRootOffset))
32	if err != nil {
33		return ConsensusState{}, err
34	}
35
36	return ConsensusState{
37		Timestamp:   timestamp,
38		StateRoot:   stateRoot,
39		StorageRoot: storageRoot,
40	}, nil
41}
42
43func extractUint64(data []byte, offset int) (uint64, error) {
44	if offset < 0 || offset+8 > len(data) {
45		return 0, ErrConsensusStateTooShort
46	}
47
48	return binary.BigEndian.Uint64(data[offset : offset+8]), nil
49}
50
51func extractBytes32(data []byte, offset int) ([]byte, error) {
52	if offset < 0 || offset+32 > len(data) {
53		return nil, ErrConsensusStateTooShort
54	}
55
56	out := make([]byte, 32)
57	copy(out, data[offset:offset+32])
58
59	return out, nil
60}
61
62// VerifyCommitmentKey checks that proofKey matches the IBC commitment key
63// derived from path. It rejects proofs whose key does not bind to the
64// expected commitment path.
65func VerifyCommitmentKey(path []byte, proofKey []byte) error {
66	expected, err := storage.IBCCommitmentKey(path)
67	if err != nil {
68		return ErrInvalidCommitmentKey
69	}
70
71	if !bytes.Equal(expected[:], proofKey) {
72		return ErrInvalidCommitmentKey
73	}
74
75	return nil
76}