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captoys/toybox/config.capnp
T
dckcandClaude Opus 5.5 f0557d29d6 capsite/toybox: egress through Flower-style switchboard handles
The switchboard now serves a Cap'n Web Handle on each of its sockets:
public (no loopback or private addresses) and local. A socket's labels
are fixed in config, so holding the socket's fd is holding that handle;
constrain(labels) returns a narrower one, as Flower's Constrain returns
a narrower fd. Labels only accumulate: a missing key matches anything,
and a key both sides set must agree (labels.js, shared by both).

The switchboard enforces the labels; toybox's Egress no longer checks
URLs itself. It opens a session to its one switchboard socket, constrains
the handle to the vat's grant, and forwards through it; a WebSocket
crosses the session as a pair of message streams. A vat narrows its own
grant with env.egress.constrain().

Grants are now labels as JSON. One stored before, a bare host[:port],
reads as {host, port}.

pnpm start and the systemd units give toybox the public handle; the
switchboard unit binds the local one in its own 0700 runtime directory.
The tests give their toybox the local handle to reach an echo server,
and check that a toybox holding only the public one never reaches it.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
2026-10-13 21:44:29 -05:00

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Cap'n Proto

# toybox: vats whose code is installed at runtime, each a Durable Object facet.
#
# Sockets have no address here: whoever starts workerd hands them in
# (-S name=fd from systemd, or -s name=addr), so holding a socket is the
# authority it grants. `state` is likewise overridden with -d state=<dir>,
# and the switchboard's address with -e switchboard=<addr>.
using Workerd = import "/workerd/workerd.capnp";
const config :Workerd.Config = (
services = [
(name = "main", worker = .supervisor),
(name = "nowhere", network = (allow = [])),
# the way out: one switchboard socket, i.e. one handle (see switchboard.capnp)
(name = "switchboard", external = (address = "unix:switchboard.sock", http = ())),
(name = "state", disk = (path = "state", writable = true)),
],
sockets = [
# reach a running vat by name
(name = "http", http = (), service = (name = "main", entrypoint = "Public")),
# install code into a vat and (re)start it
(name = "admin", http = (), service = (name = "main", entrypoint = "Admin")),
],
);
const supervisor :Workerd.Worker = (
compatibilityDate = "2026-10-01",
modules = [
(name = "supervisor.js", esModule = embed "supervisor.js"),
(name = "labels.js", esModule = embed "labels.js"),
(name = "capnweb", esModule = embed "node_modules/capnweb/dist/index-workers.js"),
],
durableObjectNamespaces = [(className = "Vat", uniqueKey = "toybox-vat", enableSql = true)],
durableObjectStorage = (localDisk = "state"),
bindings = [
(name = "VATS", durableObjectNamespace = "Vat"),
(name = "LOADER", workerLoader = ()),
(name = "SWITCHBOARD", service = "switchboard"),
],
globalOutbound = "nowhere",
);