jschoubben
ceaa616d01
A node that reports file-references gets the digest and size of each file over 64 KiB that may travel so, and the content is put in the bucket declaration-files before the declaration is sent; others get every content inline. The controller alone writes the bucket and node-engines read an object by name (the four grants the node-engine's own fetch makes, no list, no write). An object goes a day after no node's latest declaration names it. The near-limit condition warns at 75 percent, and a test holds the control node's declaration, in the reference form, under half the bus's largest message.
95 lines
3.7 KiB
Go
95 lines
3.7 KiB
Go
package link
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import (
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"context"
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"encoding/json"
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"fmt"
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"time"
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)
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// Signer is whatever holds the control plane's signing key.
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type Signer interface {
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Sign(ctx context.Context, message []byte) ([]byte, error)
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}
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// ActingGate is what every send passes before it is made (novox/hq to-be 45 §6): whether this process
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// may act under the controller's lease. Set by the controller; nil passes every send — a test, a tool.
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var ActingGate func(ctx context.Context) error
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// Declare sends a node what it should be, signed.
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//
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// The signature is over the declaration exactly as it is published — the same bytes the node
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// verifies. Anything that re-encoded between here and there would produce a signature over
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// something else, and the node would refuse a declaration that was genuinely the mesh's.
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//
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// Published to the node's own queue, which its account alone may read.
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func Declare(ctx context.Context, bus Bus, signer Signer, node string,
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declaration []byte, timeout time.Duration) error {
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if !json.Valid(declaration) {
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return fmt.Errorf("refusing to send %s something that is not a declaration", node)
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}
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// **At the send, not only where it was composed**: a lease lost between the two stops this one.
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if ActingGate != nil {
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if err := ActingGate(ctx); err != nil {
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return fmt.Errorf("%s was not sent its declaration: %w", node, err)
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}
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}
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signature, err := signer.Sign(ctx, declaration)
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if err != nil {
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return fmt.Errorf("cannot sign a declaration for %s: %w", node, err)
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}
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body, err := Envelope(declaration, signature)
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if err != nil {
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return err
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}
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// **Measured before it is sent** (novox/hq issue 1689): the bare bus error said only "maximum payload
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// exceeded", on 2026-10-21 for the control node's declaration, 2 KB over. The limit is the connection's own.
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if limit := payloadLimitOf(bus); limit > 0 {
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size := int64(len(body))
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if DeclarationMeasured != nil {
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DeclarationMeasured(ctx, node, size, limit)
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}
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if size > limit {
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return fmt.Errorf("%s's declaration is %d bytes on the wire (%d bytes of declaration, signed and encoded), "+
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"over the bus's largest message of %d bytes by %d: it cannot be sent (novox/hq issue 1689)",
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node, size, len(declaration), limit, size-limit)
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}
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}
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publish, cancel := context.WithTimeout(ctx, timeout)
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defer cancel()
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return bus.PublishDeclaration(publish, node, body)
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}
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// Envelope is the message a declaration goes on the bus as: the declaration and its signature, each as base64 in one JSON
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// document. Its length is what the bus's largest message bounds.
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func Envelope(declaration, signature []byte) ([]byte, error) {
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return json.Marshal(Signed{Declaration: declaration, Signature: signature})
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}
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// NearTheLimit is the share of the bus's largest message at which a declaration is said to be near it: three quarters, so that
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// a declaration which should stay far from the limit raises the condition while there is still room to act (novox/hq ADR 0486
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// §8; the first fix of issue 1689 warned at nine tenths while every file was still inline).
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const NearTheLimit = 0.75
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// DeclarationMeasured is told, at every send of a declaration, its size on the wire and the bus's largest message,
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// so the controller raises a condition when it nears the limit and clears it when it is back under (issue 1689).
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// Set by the controller; nil in a test or a tool.
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var DeclarationMeasured func(ctx context.Context, node string, size, limit int64)
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// payloadLimiter is a bus that knows its largest message.
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type payloadLimiter interface{ MaxPayload() int64 }
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// payloadLimitOf is the bus's largest message in bytes, or 0 when the bus does not say.
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func payloadLimitOf(bus Bus) int64 {
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if l, ok := bus.(payloadLimiter); ok {
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return l.MaxPayload()
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}
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return 0
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}
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