| 1 | package hostops |
| 2 | |
| 3 | import ( |
| 4 | "context" |
| 5 | "crypto/rand" |
| 6 | "crypto/sha256" |
| 7 | "crypto/subtle" |
| 8 | "encoding/hex" |
| 9 | "encoding/json" |
| 10 | "errors" |
| 11 | "os" |
| 12 | "time" |
| 13 | |
| 14 | "github.com/carlosframework/platform/internal/release" |
| 15 | ) |
| 16 | |
| 17 | // The shared mail-resource gate serializes every enabled SES, DNS and |
| 18 | // email-index mutation deployment-wide. It has no expiry and no takeover: |
| 19 | // a gate retained after an uncertain effect waits for fenced |
| 20 | // reconciliation. Possession is proved by a secret token whose SHA-256 is |
| 21 | // stored; reading the gate object is not possession. |
| 22 | type MailGateOwner struct{ Console, Enrollment, Controller string } |
| 23 | type MailGateScope struct{ Account, App, AppID, Operation string } |
| 24 | |
| 25 | type MailGateLease struct { |
| 26 | ID string |
| 27 | Owner MailGateOwner |
| 28 | Scope MailGateScope |
| 29 | token string |
| 30 | // revision of the held state this lease wrote |
| 31 | revision uint64 |
| 32 | } |
| 33 | |
| 34 | type mailGate struct { |
| 35 | V int `json:"v"` |
| 36 | Revision uint64 `json:"revision"` |
| 37 | State string `json:"state"` |
| 38 | ID string `json:"id"` |
| 39 | Owner MailGateOwner `json:"owner"` |
| 40 | Scope MailGateScope `json:"scope"` |
| 41 | TokenSHA256 string `json:"token_sha256"` |
| 42 | HeldAt time.Time `json:"held_at,omitempty"` |
| 43 | // Members is every app operation/effect this hold admitted, recorded |
| 44 | // BEFORE the member's operation or effect exists, so a reconciler finds |
| 45 | // every effect the hold could have issued without scanning admissions. |
| 46 | Members []MailGateMember `json:"members,omitempty"` |
| 47 | // Reconciling is set by the reconciler's fencing CAS (revision bumped, |
| 48 | // token cleared): no lease of the old holder checks any more. |
| 49 | Reconciling bool `json:"reconciling,omitempty"` |
| 50 | // Reconciled is the evidence of the last fenced reconciliation. |
| 51 | Reconciled *MailGateReconciliation `json:"reconciled,omitempty"` |
| 52 | } |
| 53 | |
| 54 | // MailGateMember names one app effect admitted under a held gate. |
| 55 | type MailGateMember struct { |
| 56 | Account string `json:"account"` |
| 57 | App string `json:"app"` |
| 58 | AppID string `json:"app_id"` |
| 59 | Operation string `json:"operation"` |
| 60 | Effect string `json:"effect"` |
| 61 | } |
| 62 | |
| 63 | type mailGateLeaseKey struct{} |
| 64 | |
| 65 | func WithMailGateLease(ctx context.Context, l *MailGateLease) context.Context { |
| 66 | return context.WithValue(ctx, mailGateLeaseKey{}, l) |
| 67 | } |
| 68 | func MailGateLeaseFrom(ctx context.Context) (*MailGateLease, bool) { |
| 69 | l, ok := ctx.Value(mailGateLeaseKey{}).(*MailGateLease) |
| 70 | return l, ok && l != nil |
| 71 | } |
| 72 | |
| 73 | func (w *ControlWriter) readMailGate(ctx context.Context) (mailGate, string, error) { |
| 74 | body, tag, err := w.raw.Get(ctx, MailGateKey) |
| 75 | if errors.Is(err, os.ErrNotExist) { |
| 76 | return mailGate{V: 1, State: "free"}, "", nil |
| 77 | } |
| 78 | if err != nil { |
| 79 | return mailGate{}, "", err |
| 80 | } |
| 81 | var g mailGate |
| 82 | if err = json.Unmarshal(body, &g); err != nil { |
| 83 | return mailGate{}, "", err |
| 84 | } |
| 85 | if g.V != 1 || g.Revision == 0 || (g.State != "free" && g.State != "held") || tag == "" { |
| 86 | return mailGate{}, "", ErrIdentity |
| 87 | } |
| 88 | return g, tag, nil |
| 89 | } |
| 90 | |
| 91 | func tokenDigest(token string) string { |
| 92 | sum := sha256.Sum256([]byte(token)) |
| 93 | return hex.EncodeToString(sum[:]) |
| 94 | } |
| 95 | |
| 96 | func (w *ControlWriter) AcquireMailGate(ctx context.Context, owner MailGateOwner, scope MailGateScope) (*MailGateLease, error) { |
| 97 | if err := w.ready(); err != nil { |
| 98 | return nil, err |
| 99 | } |
| 100 | if owner.Console == "" || owner.Enrollment == "" || owner.Controller == "" { |
| 101 | return nil, ErrIdentity |
| 102 | } |
| 103 | g, tag, err := w.readMailGate(ctx) |
| 104 | if err != nil { |
| 105 | return nil, err |
| 106 | } |
| 107 | if g.State != "free" { |
| 108 | return nil, ErrPending |
| 109 | } |
| 110 | var id, secret [16]byte |
| 111 | if _, err = rand.Read(id[:]); err != nil { |
| 112 | return nil, err |
| 113 | } |
| 114 | if _, err = rand.Read(secret[:]); err != nil { |
| 115 | return nil, err |
| 116 | } |
| 117 | token := hex.EncodeToString(secret[:]) |
| 118 | g.Revision++ |
| 119 | g.State, g.ID, g.Owner, g.Scope, g.TokenSHA256, g.HeldAt = "held", hex.EncodeToString(id[:]), owner, scope, tokenDigest(token), w.now().UTC() |
| 120 | g.Members, g.Reconciling = nil, false |
| 121 | body, err := json.Marshal(g) |
| 122 | if err != nil { |
| 123 | return nil, err |
| 124 | } |
| 125 | if _, err = w.raw.Put(ctx, MailGateKey, body, tag); err != nil { |
| 126 | return nil, err |
| 127 | } |
| 128 | return &MailGateLease{ID: g.ID, Owner: owner, Scope: scope, token: token, revision: g.Revision}, nil |
| 129 | } |
| 130 | |
| 131 | // CheckMailGate proves the exact held revision belongs to this lease. |
| 132 | func (w *ControlWriter) CheckMailGate(ctx context.Context, l *MailGateLease) error { |
| 133 | if err := w.ready(); err != nil { |
| 134 | return err |
| 135 | } |
| 136 | if l == nil || l.token == "" { |
| 137 | return ErrPending |
| 138 | } |
| 139 | g, _, err := w.readMailGate(ctx) |
| 140 | if err != nil { |
| 141 | return err |
| 142 | } |
| 143 | if g.State != "held" || g.ID != l.ID || g.Owner != l.Owner || g.Revision != l.revision || |
| 144 | subtle.ConstantTimeCompare([]byte(g.TokenSHA256), []byte(tokenDigest(l.token))) != 1 { |
| 145 | return ErrPending |
| 146 | } |
| 147 | return nil |
| 148 | } |
| 149 | |
| 150 | // ReleaseMailGate frees the gate only from this lease's exact held revision. |
| 151 | // Callers release only after every issued effect under the gate settled |
| 152 | // complete; an uncertain effect retains the gate. |
| 153 | func (w *ControlWriter) ReleaseMailGate(ctx context.Context, l *MailGateLease) error { |
| 154 | if err := w.CheckMailGate(ctx, l); err != nil { |
| 155 | return err |
| 156 | } |
| 157 | g, tag, err := w.readMailGate(ctx) |
| 158 | if err != nil { |
| 159 | return err |
| 160 | } |
| 161 | if g.Revision != l.revision { |
| 162 | return ErrPending |
| 163 | } |
| 164 | g.Revision++ |
| 165 | g.State, g.TokenSHA256, g.HeldAt, g.Members = "free", "", time.Time{}, nil |
| 166 | body, err := json.Marshal(g) |
| 167 | if err != nil { |
| 168 | return err |
| 169 | } |
| 170 | _, err = w.raw.Put(ctx, MailGateKey, body, tag) |
| 171 | return err |
| 172 | } |
| 173 | |
| 174 | // RecordMailGateMember durably names one app effect this lease is about to |
| 175 | // admit. It must succeed before the member's BeginExclusive/ResumeExclusive |
| 176 | // and Issue. The revision is unchanged (the ETag CAS orders it), so the |
| 177 | // lease keeps checking. |
| 178 | func (w *ControlWriter) RecordMailGateMember(ctx context.Context, l *MailGateLease, m MailGateMember) error { |
| 179 | if m.Account == "" || m.App == "" || m.AppID == "" || m.Operation == "" || m.Effect == "" { |
| 180 | return ErrIdentity |
| 181 | } |
| 182 | for attempt := 1; ; attempt++ { |
| 183 | if err := w.CheckMailGate(ctx, l); err != nil { |
| 184 | return err |
| 185 | } |
| 186 | g, tag, err := w.readMailGate(ctx) |
| 187 | if err != nil { |
| 188 | return err |
| 189 | } |
| 190 | if g.Revision != l.revision || g.Reconciling { |
| 191 | return ErrPending |
| 192 | } |
| 193 | for _, have := range g.Members { |
| 194 | if have == m { |
| 195 | return nil |
| 196 | } |
| 197 | } |
| 198 | g.Members = append(g.Members, m) |
| 199 | body, err := json.Marshal(g) |
| 200 | if err != nil { |
| 201 | return err |
| 202 | } |
| 203 | if _, err = w.raw.Put(ctx, MailGateKey, body, tag); err == nil || !errors.Is(err, release.ErrCASConflict) || attempt >= casRetries { |
| 204 | return err |
| 205 | } |
| 206 | } |
| 207 | } |
| 208 | |
amadan