Setting up a farm meant reading five fields off each printer's screen into
printers.toml, and the serial is the one that punishes a typo: 15 unspaced
alphanumerics that address Bambu's MQTT topics, so a wrong character
produces a gateway that connects to the broker, subscribes to a topic no
printer publishes, and reports nothing.
Two mechanisms, because they fail in different places:
SSDP (`listen_ssdp`) hears the announcements Bambu printers send to
239.255.255.250 unsolicited, on 2021 and 1990. It learns the most - the
model and the operator's own name for the printer come only from here - but
multicast does not cross a router, so it finds nothing from a gateway on a
different VLAN than its printers, which is an ordinary way to run a
workshop.
The TLS certificate (`identify`) is the dependable one. Every Bambu printer
puts its serial in the subject CN of the certificate it presents on 8883,
readable with no credentials, no MQTT session and across subnets. Verified
against both real printers: a P1P gives CN = 01S09B441900143 (issuer
BBL CA, TLS 1.2) and an H2C CN = 31B8BP5A1800585 (BBL Device CA O1C2-V2,
TLS 1.3), each an exact match for what printers.toml already said. A blind
sweep of their /24 found exactly those two and nothing else, in 24s.
Reading an unverifiable certificate is deliberate and worth being plain
about: it is being read as a name tag, not trusted. There is nothing to
verify it against - the serial is what is being learned, and a P1P does not
chain to the bundled Bambu CA at all. Trust is still decided by
BambuTls::resolve and the trust-on-first-connect pinning, where credentials
actually get sent. `to_string` and not the deprecated `as_utf8`, which
truncates at an interior NUL; `valid_serial` would reject the untruncated
form anyway, which is why the shape is checked rather than the name
trusted. `entries_by_nid` on the subject specifically, because an issuer's
CN sits earlier in the DER and anything scanning for the first CN reports
the certificate authority as the printer.
Three decisions that are not incidental:
It prints a [[printer]] block and does not write printers.toml. Discovery
cannot learn an access code - that code is the only thing between anyone on
the network and control of the machine - so every block is incomplete by
construction, and fleet::load rejects an empty access_code. Writing a
half-finished entry in would stop the gateway starting.
`vendor = "bambu"`, never a guessed v1/v2. That value auto-detects on
connect, and a firmware update can move a physical printer between dialects,
so a guess in a file goes stale silently. There is a tempting correlation in
the two printers to hand - the v1 machine negotiated TLS 1.2 and the v2 one
TLS 1.3 - but two samples is not evidence.
A sweep refuses anything larger than a /24. 256 addresses is every printer
anyone has on one segment, and a mistyped /8 would be sixteen million
connection attempts across somebody's network.
The SSDP path has not received a real announcement: the only host available
to test from is routed to the printers rather than on their segment, so
their multicast cannot arrive. Hence the parser is tolerant - a header
spelled differently costs one field, not the printer - and `raw` mode dumps
every datagram, so the first run on a real segment is a test that shows its
working rather than only its conclusion.
openssl is named directly for the CN read. It is already in the tree -
native-tls is openssl on Linux - so this adds nothing to the build, and
Apache-2.0 passes `cargo deny check licenses`.
README/certs/README/.env.example/printers.example.toml were all still
describing this as a learning-stage stub with no real printer protocol
clients - rewritten to reflect the real Bambu MQTT client, cert
auto-pinning, and marlin serial connection that now exist.
- Remove examples/fetch_bambu_cert.rs: its manual fetch-and-save workflow
is now what BambuPrinter::connect()'s ensure_trusted does automatically
on every connect, so it has no remaining use case.
- Fix examples/printer_polymorphism.rs, which no longer compiled -
dispatch_gcode was replaced by real methods earlier this session;
swapped in print_status() as the vendor-only-extension example.
- Remove Config::bambu_ca_cert_overrides/bambu_require_valid_cert and the
.env vars documenting them - confirmed dead (nothing read them),
fully superseded by printers.toml's per-printer ca_cert_path/
require_valid_cert plus automatic trust-on-first-connect pinning.
- Fix stale doc comments in printer/mod.rs and printer/bambu.rs that
described certificate trust and MQTT as not built yet, or referencing
the now-removed example.
No behavior change in the daemon itself - verified with cargo build
--examples and a live run of printer_polymorphism and auto_connect_bambu
against the real P1P/H2C printers.
- GenericPrinter grows upload_project_file, send_gcode_line, and a
generic upload_gcode<P> driver that streams a whole gcode file line by
line through any vendor's send_gcode_line.
- PrusaSerialPrinter's connect/send_gcode_line are real (not stubs): a
held-open MarlinSerialConnection (src/printer/marlin_serial.rs) writes
each line and waits for Marlin's "ok" before sending the next. Config
changed from com_port: i16 to port: String + baud_rate: u32 to hold a
real device path.
- Bambu: BambuGenericPrinter + BambuV1Printer/BambuV2Printer collapsed
into one BambuPrinter, since which MQTT/BambuMQTT version (v3.1.1/v1
vs v5/v2) a printer speaks is discovered at connect() time (or forced),
not something config should pick a type for - the same physical
printer can change after a firmware update. printers.toml gets a new
"bambu" vendor (auto-detect, the default) alongside bambu_v1/bambu_v2
(force a specific one).
- Bambu's gcode_line request is now built for real via
continuum-schema-instance against continuum-schemas' JSON Schema,
picking the v1 or v2 schema directory based on the detected protocol
version, instead of a hand-written serde struct.
- Added rumqttc as a dependency (not wired up yet - the real MQTT
v5-then-v3.1.1 fallback connect and the publish/receive plumbing are
still stubs).
Completes the GenericPrinter -> BambuGenericPrinter -> BambuV1/V2 chain this
project wanted from the start. BambuGenericPrinter holds the fields and
behavior every Bambu printer shares (access code, serial number, CA trust,
the TLS test/fetch methods); BambuV1Printer and BambuV2Printer each *have*
one (composition) and are now genuinely separate types, ready to carry
flavour-specific report-schema fields later. Also threads through a new
'sn' (serial number) field the real MQTT topics will need.
Adds real 'fetch the CA automatically' capability, verified against a live
TLS server (not just compiled):
- BambuGenericPrinter::fetch_certificate() does trust-on-first-connect —
connects once with verification disabled, captures the certificate the
printer actually presents via native_tls's peer_certificate()/to_der(),
and returns it as PEM. Deliberately a method you call once by hand
(examples/fetch_bambu_cert.rs), not something connect() falls back to
silently, since TOFU trusts whoever's on the network the moment you run
it. Verified end-to-end against a local openssl s_server: the fetched
PEM's SHA-256 fingerprint exactly matched the server's real certificate.
- Verified the other direction too: test_bambu_certs (bundled-CA mode)
correctly REJECTS that same test server's cert, since it wasn't signed
by the real Bambu CA.
Splitting BambuV1Printer/BambuV2Printer into distinct types broke the
PrinterHandle::BambuV1(x) | PrinterHandle::BambuV2(x) or-pattern in both
examples (or-patterns require every alternative to bind the same type) —
fixed by giving each variant its own match arm.
New:
- printers.example.toml (committed template) / printers.toml (gitignored,
real hosts + access codes don't belong in git) — a list of real printers
with vendor, host, access_code/api_key/com_port, and an optional
per-printer CA override.
- src/fleet.rs loads that file into ready-to-use PrinterHandles, matching
vendor strings to the right constructor.
- BambuPrinter::test_tls_handshake() does a real (blocking, one-shot) TLS
handshake to port 8883 using that printer's configured BambuTls trust
mode — no MQTT protocol, just 'does the certificate verify'. Added
native-tls and toml as direct dependencies for this.
- examples/test_bambu_certs.rs loads printers.toml and runs the handshake
test against every Bambu entry.
Also fixes a real bug found while testing against unreachable IPs: plain
TcpStream::connect has no timeout and hung indefinitely on an offline
printer — switched to connect_timeout (5s).
Verified with cargo check --all-targets (0 errors) and by actually running
test_bambu_certs against a local printers.toml (correctly errored on a
missing cert file, then correctly timed out against unreachable test IPs
instead of hanging).
octoturge