Add calendar/address-book sharing backend

Introduce internal/db, a small SQLite-backed store (pure-Go modernc.org/sqlite, no CGO) at <data_dir>/nidus.db holding calendar_shares and addressbook_shares grant tables (owner, resource name, shared-with user, read/write permission). This is the first step towards user management and a web UI: a real datastore that a future admin CLI/UI can build on, instead of the static config.yaml. Wire sharing into the CalDAV/CardDAV backends: - ListCalendars/ListAddressBooks now also include resources shared with the requesting user, exposed under the synthetic local name "<owner>~<name>" in the grantee's own home-set — no separate account, no data copying, the object still physically lives under the owner's store.Store namespace. - All read paths (Get/List/QueryCalendarObjects, address book equivalents) resolve the synthetic name back to (owner, real name) and require any share (read or write) to exist. - All write paths (Put/Delete object, DeleteCalendar/AddressBook) additionally require a write-permission share; read-only shares get a 403 Forbidden. - CreateCalendar/CreateAddressBook remain scoped to the acting user's own namespace — sharing an existing collection is done via ShareCalendar/ ShareAddressBook, not by creating one directly in someone else's name. Add internal/db/shares_test.go (grant/lookup/update/unshare/list semantics) and internal/{caldav,carddav}/backend_test.go (shared calendar/address book visibility, write permission enforcement, unauthorized access rejection). Update README (features, new "Sharing calendars and address books" section, project layout, dependencies) and copilot-instructions.md to document the new package and sharing model. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
2026-08-18 20:10:31 +02:00
parent 21bac66b07
commit daa51d62b1
12 changed files with 1041 additions and 59 deletions
@@ -0,0 +1,227 @@
+package db
+
+import (
+	"database/sql"
+	"errors"
+	"fmt"
+)
+
+// Permission is the access level granted by a share.
+type Permission string
+
+const (
+	PermRead  Permission = "read"
+	PermWrite Permission = "write"
+)
+
+// ErrShareNotFound is returned when revoking a share that doesn't exist.
+var ErrShareNotFound = errors.New("share not found")
+
+// CalendarShare describes a grant of access to owner's calendar to another
+// user.
+type CalendarShare struct {
+	Owner        string
+	CalendarName string
+	SharedWith   string
+	Permission   Permission
+}
+
+// ShareCalendar grants sharedWith access (read or write) to owner's
+// calendar calName. Calling it again for the same (owner, calName,
+// sharedWith) updates the permission.
+func (d *DB) ShareCalendar(owner, calName, sharedWith string, perm Permission) error {
+	if perm != PermRead && perm != PermWrite {
+		return fmt.Errorf("invalid permission %q", perm)
+	}
+	_, err := d.conn.Exec(`
+		INSERT INTO calendar_shares (owner, calendar_name, shared_with, permission)
+		VALUES (?, ?, ?, ?)
+		ON CONFLICT (owner, calendar_name, shared_with)
+		DO UPDATE SET permission = excluded.permission`,
+		owner, calName, sharedWith, string(perm))
+	if err != nil {
+		return fmt.Errorf("sharing calendar: %w", err)
+	}
+	return nil
+}
+
+// UnshareCalendar revokes sharedWith's access to owner's calendar calName.
+func (d *DB) UnshareCalendar(owner, calName, sharedWith string) error {
+	res, err := d.conn.Exec(`
+		DELETE FROM calendar_shares
+		WHERE owner = ? AND calendar_name = ? AND shared_with = ?`,
+		owner, calName, sharedWith)
+	if err != nil {
+		return fmt.Errorf("unsharing calendar: %w", err)
+	}
+	n, err := res.RowsAffected()
+	if err != nil {
+		return fmt.Errorf("unsharing calendar: %w", err)
+	}
+	if n == 0 {
+		return ErrShareNotFound
+	}
+	return nil
+}
+
+// SharesOfCalendar lists everyone owner's calendar calName has been shared
+// with.
+func (d *DB) SharesOfCalendar(owner, calName string) ([]CalendarShare, error) {
+	rows, err := d.conn.Query(`
+		SELECT owner, calendar_name, shared_with, permission
+		FROM calendar_shares
+		WHERE owner = ? AND calendar_name = ?
+		ORDER BY shared_with`,
+		owner, calName)
+	if err != nil {
+		return nil, fmt.Errorf("listing calendar shares: %w", err)
+	}
+	defer rows.Close()
+	return scanCalendarShares(rows)
+}
+
+// CalendarsSharedWith lists all calendars (from any owner) that have been
+// shared with user.
+func (d *DB) CalendarsSharedWith(user string) ([]CalendarShare, error) {
+	rows, err := d.conn.Query(`
+		SELECT owner, calendar_name, shared_with, permission
+		FROM calendar_shares
+		WHERE shared_with = ?
+		ORDER BY owner, calendar_name`,
+		user)
+	if err != nil {
+		return nil, fmt.Errorf("listing calendars shared with user: %w", err)
+	}
+	defer rows.Close()
+	return scanCalendarShares(rows)
+}
+
+// CalendarShare looks up the share record granting user access to
+// owner's calendar calName, if any.
+func (d *DB) CalendarShareFor(owner, calName, user string) (*CalendarShare, error) {
+	row := d.conn.QueryRow(`
+		SELECT owner, calendar_name, shared_with, permission
+		FROM calendar_shares
+		WHERE owner = ? AND calendar_name = ? AND shared_with = ?`,
+		owner, calName, user)
+
+	var s CalendarShare
+	var perm string
+	if err := row.Scan(&s.Owner, &s.CalendarName, &s.SharedWith, &perm); err != nil {
+		if errors.Is(err, sql.ErrNoRows) {
+			return nil, ErrShareNotFound
+		}
+		return nil, fmt.Errorf("looking up calendar share: %w", err)
+	}
+	s.Permission = Permission(perm)
+	return &s, nil
+}
+
+func scanCalendarShares(rows *sql.Rows) ([]CalendarShare, error) {
+	var shares []CalendarShare
+	for rows.Next() {
+		var s CalendarShare
+		var perm string
+		if err := rows.Scan(&s.Owner, &s.CalendarName, &s.SharedWith, &perm); err != nil {
+			return nil, fmt.Errorf("scanning calendar share: %w", err)
+		}
+		s.Permission = Permission(perm)
+		shares = append(shares, s)
+	}
+	return shares, rows.Err()
+}
+
+// AddressBookShare describes a grant of access to owner's address book to
+// another user.
+type AddressBookShare struct {
+	Owner           string
+	AddressBookName string
+	SharedWith      string
+	Permission      Permission
+}
+
+// ShareAddressBook grants sharedWith access (read or write) to owner's
+// address book bookName.
+func (d *DB) ShareAddressBook(owner, bookName, sharedWith string, perm Permission) error {
+	if perm != PermRead && perm != PermWrite {
+		return fmt.Errorf("invalid permission %q", perm)
+	}
+	_, err := d.conn.Exec(`
+		INSERT INTO addressbook_shares (owner, addressbook_name, shared_with, permission)
+		VALUES (?, ?, ?, ?)
+		ON CONFLICT (owner, addressbook_name, shared_with)
+		DO UPDATE SET permission = excluded.permission`,
+		owner, bookName, sharedWith, string(perm))
+	if err != nil {
+		return fmt.Errorf("sharing address book: %w", err)
+	}
+	return nil
+}
+
+// UnshareAddressBook revokes sharedWith's access to owner's address book
+// bookName.
+func (d *DB) UnshareAddressBook(owner, bookName, sharedWith string) error {
+	res, err := d.conn.Exec(`
+		DELETE FROM addressbook_shares
+		WHERE owner = ? AND addressbook_name = ? AND shared_with = ?`,
+		owner, bookName, sharedWith)
+	if err != nil {
+		return fmt.Errorf("unsharing address book: %w", err)
+	}
+	n, err := res.RowsAffected()
+	if err != nil {
+		return fmt.Errorf("unsharing address book: %w", err)
+	}
+	if n == 0 {
+		return ErrShareNotFound
+	}
+	return nil
+}
+
+// AddressBooksSharedWith lists all address books (from any owner) that
+// have been shared with user.
+func (d *DB) AddressBooksSharedWith(user string) ([]AddressBookShare, error) {
+	rows, err := d.conn.Query(`
+		SELECT owner, addressbook_name, shared_with, permission
+		FROM addressbook_shares
+		WHERE shared_with = ?
+		ORDER BY owner, addressbook_name`,
+		user)
+	if err != nil {
+		return nil, fmt.Errorf("listing address books shared with user: %w", err)
+	}
+	defer rows.Close()
+
+	var shares []AddressBookShare
+	for rows.Next() {
+		var s AddressBookShare
+		var perm string
+		if err := rows.Scan(&s.Owner, &s.AddressBookName, &s.SharedWith, &perm); err != nil {
+			return nil, fmt.Errorf("scanning address book share: %w", err)
+		}
+		s.Permission = Permission(perm)
+		shares = append(shares, s)
+	}
+	return shares, rows.Err()
+}
+
+// AddressBookShareFor looks up the share record granting user access to
+// owner's address book bookName, if any.
+func (d *DB) AddressBookShareFor(owner, bookName, user string) (*AddressBookShare, error) {
+	row := d.conn.QueryRow(`
+		SELECT owner, addressbook_name, shared_with, permission
+		FROM addressbook_shares
+		WHERE owner = ? AND addressbook_name = ? AND shared_with = ?`,
+		owner, bookName, user)
+
+	var s AddressBookShare
+	var perm string
+	if err := row.Scan(&s.Owner, &s.AddressBookName, &s.SharedWith, &perm); err != nil {
+		if errors.Is(err, sql.ErrNoRows) {
+			return nil, ErrShareNotFound
+		}
+		return nil, fmt.Errorf("looking up address book share: %w", err)
+	}
+	s.Permission = Permission(perm)
+	return &s, nil
+}