67 lines
3.2 KiB
Go
67 lines
3.2 KiB
Go
package buscompose
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import (
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"fmt"
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"slices"
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"sort"
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"strings"
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)
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// A module's ledger and the one account that writes it (issue 1966 D5; novox/hq ADR 0597 §9, design 25 § 12.4).
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//
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// **Only the tool runner's ledger credential publishes on a ledger's history** (ADR 0597 §9): one per module assignment,
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// named ledger.<machine>.<module> (KindLedger), scoped to the subjects of that module's ledger histories and snapshots, and
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// gone when the module is unassigned from the machine. The module's own account, its processes and the machine's tool
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// runner hold no publish there, so a raw publish on a history is refused by the bus. The subjects are `mesh.ledger.<module>.
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// <local name>.history.<instance>` and `mesh.ledger.<module>.<local name>.snapshot.<instance>`, one subject per instance
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// (design 25 § 12.4); the bus module that creates the ledger's history stream (B2) takes them from here.
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// LedgerHistorySubject is the subject a ledger's history is on, without the instance: an operation on instance I is on
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// `<LedgerHistorySubject>.<I>`.
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func LedgerHistorySubject(module, local string) string {
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return "mesh.ledger." + module + "." + local + ".history"
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}
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// LedgerSnapshotSubject is the subject a ledger's instances' snapshots are on, without the instance.
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func LedgerSnapshotSubject(module, local string) string {
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return "mesh.ledger." + module + "." + local + ".snapshot"
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}
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// LedgerPublishGrants are the publish patterns a module's ledger account is granted: the histories and the snapshots of the
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// ledgers named, every instance of each, and nothing else. Sorted.
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func LedgerPublishGrants(module string, locals []string) []string {
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var out []string
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for _, local := range locals {
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out = append(out, LedgerHistorySubject(module, local)+".>", LedgerSnapshotSubject(module, local)+".>")
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}
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sort.Strings(out)
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return out
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}
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// writesLedger is a module's ledger account publishing on that module's own ledgers' histories and snapshots, and no other
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// principal (ADR 0597 §9).
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func writesLedger(p Principal, pattern string) bool {
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return p.Kind == KindLedger && slices.Contains(LedgerPublishGrants(p.Module, p.Ledgers), pattern)
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}
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// ledgerSubjects are the subjects no principal but a ledger account may publish on, for the writers table.
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var ledgerSubjects = []string{"mesh.ledger.*.*.history.>", "mesh.ledger.*.*.snapshot.>"}
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// ledgerPermissions are a ledger account's whole authority: publishing on its module's ledgers, and its own reply space for
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// the stream's acknowledgements. Refused when it names no ledger or a name that is no subject token.
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func ledgerPermissions(p Principal) (Permissions, error) {
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pub := LedgerPublishGrants(p.Module, p.Ledgers)
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if len(p.Ledgers) == 0 {
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return Permissions{}, fmt.Errorf("%s asks for no ledger, so its account would publish nowhere", p.Username())
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}
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for _, l := range p.Ledgers {
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if !safeSubject.MatchString(l) || strings.Contains(l, "_") {
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return Permissions{}, fmt.Errorf("%s: %q cannot be part of a subject: a permission is a subject pattern, and this would widen it", p.Username(), l)
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}
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}
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if err := CheckWriters(p, pub); err != nil {
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return Permissions{}, err
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}
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return Permissions{Publish: pub, Subscribe: []string{p.inbox()}}, nil
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}
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