| 1 | package maintenanceguard |
| 2 | |
| 3 | import ( |
| 4 | "bytes" |
| 5 | "context" |
| 6 | "errors" |
| 7 | "os" |
| 8 | ) |
| 9 | |
| 10 | // Store is structural so release, provision and host can share these rules |
| 11 | // without importing each other. Put uses empty ETag for create-only writes. |
| 12 | type Store interface { |
| 13 | Get(context.Context, string) ([]byte, string, error) |
| 14 | Put(context.Context, string, []byte, string) (string, error) |
| 15 | } |
| 16 | type Repository struct{ store Store } |
| 17 | |
| 18 | func New(store Store) *Repository { return &Repository{store: store} } |
| 19 | |
| 20 | type ReferenceKind string |
| 21 | |
| 22 | const ( |
| 23 | RequestReference ReferenceKind = "requests" |
| 24 | AttemptReference ReferenceKind = "attempts" |
| 25 | ReceiptReference ReferenceKind = "receipts" |
| 26 | ) |
| 27 | |
| 28 | func (k ReferenceKind) valid() bool { |
| 29 | return k == RequestReference || k == AttemptReference || k == ReceiptReference |
| 30 | } |
| 31 | |
| 32 | // PutReference stores permanent, nonsecret metadata. Expiring private payloads |
| 33 | // belong elsewhere: active guards must keep resolving these immutable bytes. |
| 34 | // The caller validates metadata, ownership and any encrypted payload bindings. |
| 35 | func (r *Repository) PutReference(ctx context.Context, host string, kind ReferenceKind, id string, raw []byte) (Reference, error) { |
| 36 | if !kind.valid() || len(raw) == 0 || len(raw) > MaxReferenceBytes { |
| 37 | return Reference{}, ErrInvalid |
| 38 | } |
| 39 | key, e := refKey(host, string(kind), id) |
| 40 | if e != nil { |
| 41 | return Reference{}, e |
| 42 | } |
| 43 | if e = r.putImmutable(ctx, key, raw); e != nil { |
| 44 | return Reference{}, e |
| 45 | } |
| 46 | return Reference{ID: id, Digest: digest(raw)}, nil |
| 47 | } |
| 48 | func (r *Repository) putImmutable(ctx context.Context, key string, raw []byte) error { |
| 49 | old, _, e := r.store.Get(ctx, key) |
| 50 | if e == nil { |
| 51 | if bytes.Equal(old, raw) { |
| 52 | return nil |
| 53 | } |
| 54 | return ErrConflict |
| 55 | } |
| 56 | if !errors.Is(e, os.ErrNotExist) { |
| 57 | return e |
| 58 | } |
| 59 | _, e = r.store.Put(ctx, key, raw, "") |
| 60 | return e |
| 61 | } |
| 62 | func (r *Repository) checkReference(ctx context.Context, host string, kind ReferenceKind, ref Reference) error { |
| 63 | if !ref.valid() { |
| 64 | return ErrInvalid |
| 65 | } |
| 66 | key, e := refKey(host, string(kind), ref.ID) |
| 67 | if e != nil { |
| 68 | return e |
| 69 | } |
| 70 | raw, _, e := r.store.Get(ctx, key) |
| 71 | if e != nil || len(raw) == 0 || len(raw) > MaxReferenceBytes || digest(raw) != ref.Digest { |
| 72 | return ErrUnavailable |
| 73 | } |
| 74 | return nil |
| 75 | } |
| 76 | func (r *Repository) checkGuardReferences(ctx context.Context, g Guard) error { |
| 77 | for _, v := range []struct { |
| 78 | kind ReferenceKind |
| 79 | ref Reference |
| 80 | }{{RequestReference, g.Request}, {AttemptReference, g.Attempt}} { |
| 81 | if e := r.checkReference(ctx, g.Identity.Host, v.kind, v.ref); e != nil { |
| 82 | return e |
| 83 | } |
| 84 | } |
| 85 | if g.Evidence != nil { |
| 86 | return r.checkReference(ctx, g.Identity.Host, ReceiptReference, *g.Evidence) |
| 87 | } |
| 88 | return nil |
| 89 | } |
| 90 | |
amadan