Steward 0.1.0 (in development): a DHCPv4 server with a web UI, API and CLI

Subnets served per interface, pools, reservations, options at three
levels, leases in SQLite saved before the ACK, ping and decline conflict
checks, validated changes with history and undo, users and tokens, an
audit log, a Kea importer, a sandboxed systemd unit and Debian packages.
Tested with real udhcpc and dhcpcd clients in Docker (scripts/e2e.sh).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/model/auth.go

@@ -0,0 +1,123 @@
+package model
+
+import (
+	"encoding/json"
+	"time"
+)
+
+// Grant gives access to one resource (see internal/auth).
+type Grant struct {
+	Resource string `json:"resource"` // config, leases, audit, *
+	Access   string `json:"access"`   // read or write (write implies read)
+}
+
+// User is a person or a service account.
+type User struct {
+	ID           int64      `json:"id"`
+	Username     string     `json:"username"`
+	PasswordHash string     `json:"-"`
+	HasPassword  bool       `json:"has_password"`
+	Admin        bool       `json:"admin"`
+	Grants       []Grant    `json:"grants"`
+	Disabled     bool       `json:"disabled"`
+	Comment      string     `json:"comment"`
+	CreatedAt    time.Time  `json:"created_at"`
+	UpdatedAt    time.Time  `json:"updated_at"`
+	LastLoginAt  *time.Time `json:"last_login_at,omitempty"`
+}
+
+// Token is an API token. The secret is shown once, when it is made; only
+// its hash is stored.
+type Token struct {
+	ID         int64  `json:"id"`
+	UserID     int64  `json:"user_id"`
+	Username   string `json:"username,omitempty"`
+	Name       string `json:"name"`
+	PublicID   string `json:"public_id"`
+	SecretHash string `json:"-"`
+	// Grants restrict the token to part of its user's permissions; nil
+	// means all of them.
+	Grants     []Grant    `json:"grants"`
+	ExpiresAt  *time.Time `json:"expires_at,omitempty"`
+	CreatedAt  time.Time  `json:"created_at"`
+	LastUsedAt *time.Time `json:"last_used_at,omitempty"`
+	LastUsedIP string     `json:"last_used_ip,omitempty"`
+	RevokedAt  *time.Time `json:"revoked_at,omitempty"`
+}
+
+// Session is a web UI login.
+type Session struct {
+	IDHash     string    `json:"-"`
+	UserID     int64     `json:"user_id"`
+	CSRFToken  string    `json:"-"`
+	CreatedAt  time.Time `json:"created_at"`
+	ExpiresAt  time.Time `json:"expires_at"`
+	LastSeenAt time.Time `json:"last_seen_at"`
+	IP         string    `json:"ip"`
+	UserAgent  string    `json:"user_agent"`
+}
+
+// AuditEvent records an action: logins, users and tokens, changes, lease
+// deletions.
+type AuditEvent struct {
+	ID       int64     `json:"id"`
+	Time     time.Time `json:"time"`
+	UserID   int64     `json:"user_id,omitempty"`
+	Username string    `json:"username,omitempty"`
+	Auth     string    `json:"auth,omitempty"` // session, token, socket
+	TokenID  int64     `json:"token_id,omitempty"`
+	IP       string    `json:"ip,omitempty"`
+	Action   string    `json:"action"`
+	Object   string    `json:"object,omitempty"`
+	Result   string    `json:"result"` // success, failure, denied
+	Detail   string    `json:"detail,omitempty"`
+}
+
+// Object kinds of changes.
+const (
+	KindSettings    = "settings"
+	KindSubnet      = "subnet"
+	KindReservation = "reservation"
+)
+
+// Change is one object's change: Before is nil for a create, After is nil
+// for a delete. Settings have ID 0.
+type Change struct {
+	Kind   string          `json:"kind"`
+	ID     int64           `json:"id"`
+	Label  string          `json:"label"`
+	Before json.RawMessage `json:"before,omitempty"`
+	After  json.RawMessage `json:"after,omitempty"`
+}
+
+// Action describes a change in a word.
+func (c Change) Action() string {
+	switch {
+	case c.Before == nil:
+		return "create"
+	case c.After == nil:
+		return "delete"
+	}
+	return "update"
+}
+
+// Inverse is the change that undoes c.
+func (c Change) Inverse() Change {
+	c.Before, c.After = c.After, c.Before
+	return c
+}
+
+// HistoryEntry is a saved configuration change.
+type HistoryEntry struct {
+	ID          int64     `json:"id"`
+	Time        time.Time `json:"time"`
+	UserID      int64     `json:"user_id,omitempty"`
+	Username    string    `json:"username"`
+	Via         string    `json:"via"` // web, cli, api
+	Description string    `json:"description"`
+	Changes     []Change  `json:"changes"`
+	// RevertOf is the entry this one undid; RevertedBy the entry that
+	// undid this one.
+	RevertOf   int64 `json:"revert_of,omitempty"`
+	RevertedBy int64 `json:"reverted_by,omitempty"`
+}