| 1 | package release |
| 2 | |
| 3 | import ( |
| 4 | "bytes" |
| 5 | "context" |
| 6 | "crypto/ed25519" |
| 7 | "errors" |
| 8 | "os" |
| 9 | ) |
| 10 | |
| 11 | // SystemPublication retains the exact CAS and signed bytes across retries. |
| 12 | type SystemPublication struct { |
| 13 | Component string `json:"component"` |
| 14 | Channel string `json:"channel"` |
| 15 | ID string `json:"id"` |
| 16 | ExpectedETag string `json:"expected_etag"` |
| 17 | Before []byte `json:"before,omitempty"` |
| 18 | After []byte `json:"after"` |
| 19 | } |
| 20 | |
| 21 | func (p SystemPublication) Verify(pub ed25519.PublicKey) (*SystemPointer, error) { |
| 22 | next, err := verifySystemPointer(pub, p.After, p.Component, p.Channel) |
| 23 | if err != nil { |
| 24 | return nil, err |
| 25 | } |
| 26 | if next.ActivationID != p.ID || next.CancellationID != "" { |
| 27 | return nil, ErrBadSystemPointer |
| 28 | } |
| 29 | return next, nil |
| 30 | } |
| 31 | |
| 32 | func PublishSystemPublication(ctx context.Context, s Store, pub ed25519.PublicKey, p SystemPublication) (*SystemPointer, error) { |
| 33 | next, err := p.Verify(pub) |
| 34 | if err != nil { |
| 35 | return nil, err |
| 36 | } |
| 37 | key := SystemPointerKey(p.Component, p.Channel) |
| 38 | _, err = s.Put(ctx, key, p.After, p.ExpectedETag) |
| 39 | if err == nil { |
| 40 | return next, nil |
| 41 | } |
| 42 | // A failed response can follow a committed write. Only these exact signed |
| 43 | // bytes prove completion; a different pointer never authorizes another CAS. |
| 44 | raw, _, readErr := s.Get(ctx, key) |
| 45 | if readErr == nil && bytes.Equal(raw, p.After) { |
| 46 | return next, nil |
| 47 | } |
| 48 | return nil, err |
| 49 | } |
| 50 | |
| 51 | // CancelSystemPublication competes with publication on its original pointer |
| 52 | // ETag. The fence must be durable before the actor reservation is removed. |
| 53 | func CancelSystemPublication(ctx context.Context, s Store, sg Signer, p SystemPublication) error { |
| 54 | if p.ID == "" { |
| 55 | return ErrBadSystemPointer |
| 56 | } |
| 57 | if _, err := p.Verify(sg.verifyPub()); err != nil { |
| 58 | return err |
| 59 | } |
| 60 | before := &SystemPointer{Schema: 1, Component: p.Component, Channel: p.Channel} |
| 61 | if len(p.Before) != 0 { |
| 62 | var err error |
| 63 | before, err = verifySystemPointer(sg.verifyPub(), p.Before, p.Component, p.Channel) |
| 64 | if err != nil { |
| 65 | return err |
| 66 | } |
| 67 | } |
| 68 | before.CancellationID = p.ID |
| 69 | fence, err := SignRootEnvelope(sg, before) |
| 70 | if err != nil { |
| 71 | return err |
| 72 | } |
| 73 | key := SystemPointerKey(p.Component, p.Channel) |
| 74 | raw, etag, err := s.Get(ctx, key) |
| 75 | if err == nil && bytes.Equal(raw, fence) { |
| 76 | return nil |
| 77 | } |
| 78 | if err != nil && !errors.Is(err, os.ErrNotExist) { |
| 79 | return err |
| 80 | } |
| 81 | if etag != p.ExpectedETag || (err == nil && bytes.Equal(raw, p.After)) { |
| 82 | return ErrCASConflict |
| 83 | } |
| 84 | _, err = s.Put(ctx, key, fence, p.ExpectedETag) |
| 85 | if err == nil { |
| 86 | return nil |
| 87 | } |
| 88 | raw, _, readErr := s.Get(ctx, key) |
| 89 | if readErr == nil && bytes.Equal(raw, fence) { |
| 90 | return nil |
| 91 | } |
| 92 | return err |
| 93 | } |
| 94 | |
amadan