| 1 | package hostclaim |
| 2 | |
| 3 | import ( |
| 4 | "encoding/json" |
| 5 | "errors" |
| 6 | "fmt" |
| 7 | "strings" |
| 8 | "time" |
| 9 | ) |
| 10 | |
| 11 | var ErrAckAlreadyApplied = errors.New("hostclaim: execution acknowledgement already applied") |
| 12 | |
| 13 | type ExecutionAcknowledgement struct { |
| 14 | Op string `json:"op"` |
| 15 | Enrollment string `json:"enrollment"` |
| 16 | BootID string `json:"boot_id"` |
| 17 | ControllerID string `json:"controller_id"` |
| 18 | LeaseETag string `json:"lease_etag"` |
| 19 | Expires time.Time `json:"expires"` |
| 20 | } |
| 21 | |
| 22 | // AcknowledgeExecution records the acknowledged lease for one required |
| 23 | // participant. The lease write and durable local state happen before this |
| 24 | // transition. The first acknowledgement binds the participant's boot and |
| 25 | // controller, and later ones only extend the same lease: a replacement must |
| 26 | // carry the same op, enrollment, boot and controller, a lease ETag and a |
| 27 | // strictly later expiry. Anything else is a conflicting acknowledgement and |
| 28 | // is never overwritten. |
| 29 | func AcknowledgeExecution(box string, ack ExecutionAcknowledgement) func(*Claim) error { |
| 30 | return func(c *Claim) error { |
| 31 | if !validBoxReference(box) || c.Op.Kind == "" || c.Op.Kind == KindServing || c.Op.ID == "" || ack.Op != c.Op.ID || |
| 32 | ack.Enrollment == "" || ack.BootID == "" || ack.ControllerID == "" || ack.LeaseETag == "" || ack.Expires.IsZero() || |
| 33 | !stringPresent(c.Op.Participants, box) { |
| 34 | return fmt.Errorf("%w: execution acknowledgement is not for a required active participant", ErrWrongState) |
| 35 | } |
| 36 | raw, err := json.Marshal(ack) |
| 37 | if err != nil { |
| 38 | return err |
| 39 | } |
| 40 | if c.Op.Journal == nil { |
| 41 | c.Op.Journal = map[string]string{} |
| 42 | } |
| 43 | key := "exec_ack." + box |
| 44 | if previous, ok := c.Op.Journal[key]; ok { |
| 45 | if previous == string(raw) { |
| 46 | return ErrAckAlreadyApplied |
| 47 | } |
| 48 | if !extendsAcknowledgement(previous, ack) { |
| 49 | return fmt.Errorf("%w: participant already acknowledged different lease", ErrWrongState) |
| 50 | } |
| 51 | } |
| 52 | c.Op.Journal[key] = string(raw) |
| 53 | return nil |
| 54 | } |
| 55 | } |
| 56 | |
| 57 | // extendsAcknowledgement reports whether next only extends the lease that |
| 58 | // previous acknowledged: the same op, enrollment, boot and controller, a lease |
| 59 | // ETag, and a strictly later expiry. An undecodable previous value never is. |
| 60 | func extendsAcknowledgement(previous string, next ExecutionAcknowledgement) bool { |
| 61 | dec := json.NewDecoder(strings.NewReader(previous)) |
| 62 | dec.DisallowUnknownFields() |
| 63 | var prior ExecutionAcknowledgement |
| 64 | if dec.Decode(&prior) != nil || dec.More() { |
| 65 | return false |
| 66 | } |
| 67 | return prior.Op == next.Op && prior.Enrollment == next.Enrollment && prior.BootID == next.BootID && prior.ControllerID == next.ControllerID && |
| 68 | next.LeaseETag != "" && next.Expires.After(prior.Expires) |
| 69 | } |
| 70 | |
| 71 | func validBoxReference(box string) bool { |
| 72 | if box == "" || len(box) > 128 || strings.ContainsAny(box, "/\\\x00\r\n\t ") { |
| 73 | return false |
| 74 | } |
| 75 | return true |
| 76 | } |
| 77 | |
amadan