mesh-sdk/go/delivery/enrolment.go

package delivery

import (
	"crypto/sha256"
	"encoding/base64"
	"encoding/hex"
	"encoding/json"
	"fmt"
	"net/netip"
	"strings"
	"time"

	"git.novox.be/novox/mesh-sdk/go/catalogue"
)

// **The state of the seat mesh-enrolment** (novox/hq ADR 0587 §2, issue 774): the holder's bucket `enrolments`, holding
// no secret, with two kinds of key. `node.<node>`, one per open enrolment, holds an Enrolment; `address.<address>`
// reserves one private-network address for one open enrolment and holds only the node's name. Every write is a
// compare-and-set at the revision read. The bucket keeps per-key expiry (`key-ttl`): a key at stage live carries the
// token's expiry, at asked and redeeming none (§5). It is read by the holder and, as a named reader, by the grants part,
// which composes the user `enrol.<node>` from a key at live and the vault's hash (§4). These constants are the seat's
// contract: every reader takes the names from here.
const (
	// EnrolmentModule is the module holding the seat mesh-enrolment.
	EnrolmentModule = catalogue.EnrolmentSeat
	// EnrolmentsState is its state, EnrolmentsBucket the bucket, EnrolmentsRead the name a reader's manifest declares.
	EnrolmentsState  = "enrolments"
	EnrolmentsBucket = EnrolmentModule + "_" + EnrolmentsState
	EnrolmentsRead   = EnrolmentModule + "." + EnrolmentsState

	// The stages of an open enrolment (§2, §4, §5).
	EnrolmentAsked     = "asked"
	EnrolmentLive      = "live"
	EnrolmentRedeeming = "redeeming"

	// DefaultTokenLife is a token's life when issue names none; MostTokenLife the longest it may name (§4).
	DefaultTokenLife = time.Hour
	MostTokenLife    = 24 * time.Hour

	// EnrolmentUserPrefix is the bus user a joining machine dials as, `enrol.<node>` (§4).
	EnrolmentUserPrefix = "enrol."

	enrolmentNodePrefix    = "node."
	enrolmentAddressPrefix = "address."
)

// Enrolment is one key `node.<node>` of `enrolments`: the node's name, the private-network address chosen at issue, the
// why, the caller as the runtime proved it, the ask's id, the stage, when it was issued and when the token expires, and
// from redeem the digest of the public keys presented (KeysDigest). No secret and nothing derived from the token.
type Enrolment struct {
	V          int       `json:"v"`
	Node       string    `json:"node"`
	Address    string    `json:"address"`
	Why        string    `json:"why"`
	Caller     string    `json:"caller"`
	Ask        string    `json:"ask,omitempty"`
	Stage      string    `json:"stage"`
	Issued     time.Time `json:"issued"`
	Expires    time.Time `json:"expires"`
	KeysDigest string    `json:"keys-digest,omitempty"`
}

// EnrolmentAddress is one key `address.<address>`: the node the address is reserved for, and nothing else.
type EnrolmentAddress struct {
	V    int    `json:"v"`
	Node string `json:"node"`
}

// EnrolmentNodeKey is a node's key in `enrolments`.
func EnrolmentNodeKey(node string) string { return enrolmentNodePrefix + node }

// EnrolmentAddressKey is an address's key in `enrolments`: the address as it is, its dots kept (a key's tokens).
func EnrolmentAddressKey(address string) string { return enrolmentAddressPrefix + address }

// EnrolmentKeyNode is the node a key `node.<node>` names, and whether it is one.
func EnrolmentKeyNode(key string) (string, bool) {
	node, ok := strings.CutPrefix(key, enrolmentNodePrefix)
	return node, ok && checkName("node", node) == nil
}

// EnrolmentKeyAddress is the address a key `address.<address>` names, and whether it is one.
func EnrolmentKeyAddress(key string) (string, bool) {
	address, ok := strings.CutPrefix(key, enrolmentAddressPrefix)
	if !ok {
		return "", false
	}
	_, err := netip.ParseAddr(address)
	return address, err == nil
}

// EnrolmentUser is the bus user a node enrols as.
func EnrolmentUser(node string) string { return EnrolmentUserPrefix + node }

func (e Enrolment) check() error {
	if err := checkName("node", e.Node); err != nil {
		return err
	}
	if _, err := netip.ParseAddr(e.Address); err != nil {
		return fmt.Errorf("delivery: the enrolment of %s names the address %q, which is not an address", e.Node, e.Address)
	}
	if strings.TrimSpace(e.Why) == "" || strings.TrimSpace(e.Caller) == "" {
		return fmt.Errorf("delivery: the enrolment of %s names no why or no caller", e.Node)
	}
	switch e.Stage {
	case EnrolmentAsked, EnrolmentLive:
		if e.KeysDigest != "" {
			return fmt.Errorf("delivery: the enrolment of %s at %s names presented keys, which only a redeem gives", e.Node, e.Stage)
		}
	case EnrolmentRedeeming:
		if err := checkDigest(e.KeysDigest, "the enrolment's keys digest"); err != nil {
			return err
		}
	default:
		return fmt.Errorf("delivery: the enrolment of %s is at stage %q, not asked, live or redeeming", e.Node, e.Stage)
	}
	if e.Issued.IsZero() || !e.Expires.After(e.Issued) {
		return fmt.Errorf("delivery: the enrolment of %s names no issue or an expiry not after it", e.Node)
	}
	return nil
}

// EncodeEnrolment is e as JSON at Version; it refuses what DecodeEnrolment refuses.
func EncodeEnrolment(e Enrolment) ([]byte, error) {
	if err := e.check(); err != nil {
		return nil, err
	}
	e.V = Version
	return json.Marshal(e)
}

// DecodeEnrolment reads a key `node.<node>`; it refuses an unknown version (ErrUnknownVersion), a node that is not a
// name, an address that is not one, an unknown stage, presented keys before redeem or none at it, and an expiry not
// after the issue.
func DecodeEnrolment(data []byte) (Enrolment, error) {
	var e Enrolment
	if err := decode(data, &e); err != nil {
		return Enrolment{}, err
	}
	if err := e.check(); err != nil {
		return Enrolment{}, err
	}
	return e, nil
}

// EncodeEnrolmentAddress is a key `address.<address>` reserving it for node.
func EncodeEnrolmentAddress(node string) ([]byte, error) {
	if err := checkName("node", node); err != nil {
		return nil, err
	}
	return json.Marshal(EnrolmentAddress{V: Version, Node: node})
}

// DecodeEnrolmentAddress reads a key `address.<address>`.
func DecodeEnrolmentAddress(data []byte) (EnrolmentAddress, error) {
	var a EnrolmentAddress
	if err := decode(data, &a); err != nil {
		return EnrolmentAddress{}, err
	}
	if err := checkName("node", a.Node); err != nil {
		return EnrolmentAddress{}, err
	}
	return a, nil
}

// TokenLife is the life issue's `expires` names: DefaultTokenLife when empty, refused when it is not a duration, not
// positive or longer than MostTokenLife.
func TokenLife(expires string) (time.Duration, error) {
	if strings.TrimSpace(expires) == "" {
		return DefaultTokenLife, nil
	}
	d, err := time.ParseDuration(strings.TrimSpace(expires))
	if err != nil || d <= 0 || d > MostTokenLife {
		return 0, fmt.Errorf("delivery: a token lasts a duration up to %s, such as 1h, not %q", MostTokenLife, expires)
	}
	return d, nil
}

// EnrolmentExpiry is what enrolment-expired carries (§2): the node, and the enrolment-issued event that carried the
// key's content, by its sequence on the events' stream, since the bus deleted the key before the holder heard of it.
type EnrolmentExpiry struct {
	V      int    `json:"v"`
	Node   string `json:"node"`
	Issued uint64 `json:"issued-event"`
}

// **Redeem** (§6): what a joining node-engine sends, and what the holder answers. Shared by the holder and the engine,
// which live in two repositories.

// Redeem is the redeem verb's call: the node, the public halves of its keys and its identity key's signature over
// RedeemProof. No token: the bus's login check verified it.
type Redeem struct {
	Node       string          `json:"node"`
	PublicKey  string          `json:"public_key"`
	OverlayKey string          `json:"overlay_key,omitempty"`
	SealingKey string          `json:"sealing_key"`
	ServingKey string          `json:"serving_key,omitempty"`
	Profile    map[string]any  `json:"profile,omitempty"`
	Tunnel     json.RawMessage `json:"tunnel,omitempty"`
	Proof      string          `json:"proof"`
}

// RedeemProof is the bytes a node signs with its identity key when it redeems: its name and every public key it
// presents, so a proof cannot be moved to another node or other keys. The holder builds the same bytes.
func RedeemProof(node, public, overlay, sealing, serving string) []byte {
	return []byte("novox-mesh-redeem v1\x00" + node + "\x00" + public + "\x00" + overlay + "\x00" + sealing + "\x00" + serving)
}

// KeysDigest is the digest of the public keys a redeem presents, `sha256:<hex>`: what the key at redeeming and the
// events carry, the one hash an event carries (§1).
func KeysDigest(public, overlay, sealing, serving string) string {
	sum := sha256.Sum256([]byte(strings.Join([]string{public, overlay, sealing, serving}, "\x00")))
	return "sha256:" + hex.EncodeToString(sum[:])
}

// KeysDigest is r's keys' digest.
func (r Redeem) KeysDigest() string {
	return KeysDigest(r.PublicKey, r.OverlayKey, r.SealingKey, r.ServingKey)
}

// ProofBytes is r's proof decoded from base64.
func (r Redeem) ProofBytes() ([]byte, error) { return base64.StdEncoding.DecodeString(r.Proof) }

// RedeemAnswer is what redeem answers (§6): the node, the login it dials as next, its account sealed to the sealing key it
// presented (base64), its certificate as PEM, the vault's public signing half (base64), and the vault's signature over
// SignedBytes under the context of KindEnrolment. The engine refuses an answer not signed by the key its token carries.
type RedeemAnswer struct {
	Node        string `json:"node"`
	Login       string `json:"login"`
	Account     string `json:"account"`
	Certificate string `json:"certificate"`
	Signer      string `json:"signer"`
	Signature   string `json:"signature,omitempty"`
}

// SignedBytes is what the vault signs of a: a without its signature, as JSON.
func (a RedeemAnswer) SignedBytes() []byte {
	a.Signature = ""
	raw, _ := json.Marshal(a)
	return raw
}

// **The vault's enrolment verbs** (ADR 0561 §5, ADR 0587 §3, §5), asked by mesh-enrolment alone.
const (
	EnrolmentTokenVerb = "enrolment-token"
	NodeAccountVerb    = "node-account"
)

// EnrolmentTokenAnswer is what enrolment-token answers: what the joining machine must trust (the bus's address, its
// certificate's fingerprint, the vault's public signing key in base64), never the token; Sealed holds the token sealed
// to the operator key when asked with sealed, relayed by tokens as it is; Dropped says a drop left neither the token
// nor its hash.
type EnrolmentTokenAnswer struct {
	Node        string `json:"node"`
	Broker      string `json:"broker,omitempty"`
	Fingerprint string `json:"fingerprint,omitempty"`
	Signer      string `json:"signer,omitempty"`
	Sealed      string `json:"sealed,omitempty"`
	Dropped     bool   `json:"dropped,omitempty"`
}

// NodeAccountAnswer is what node-account answers: the login minted, the account sealed to the sealing key the node
// presented (base64), never in the clear; Retired says a retire left no account.
type NodeAccountAnswer struct {
	Node    string `json:"node"`
	Login   string `json:"login,omitempty"`
	Account string `json:"account,omitempty"`
	Retired bool   `json:"retired,omitempty"`
}