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Real MQTT wiring for Bambu: connect, auto-detect v5/v3.1.1, request/reply

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Removes GenericPrinter::receive (two disconnected fire-and-forget stubs
that didn't actually give request/response) in favor of a real mechanism
in the new src/printer/bambu_mqtt.rs:

- BambuMqttSession wraps whichever rumqttc client a connection ended up
  using (v3.1.1's AsyncClient/EventLoop for BambuMQTT v1, v5's for
  BambuMQTT v2 - different types, different event/error shapes) behind
  one interface. `open()` respects ForceV1/ForceV2, and for Auto tries
  v5 first, falling back to v3.1.1 on any failure (see the module doc
  comment for why "any failure", not a precisely-matched version-
  rejection code - unverified against a live printer, no broker here to
  test against).
- Reuses BambuTls::build_connector (now pub(crate)) for rumqttc's TLS
  transport via TlsConfiguration::NativeConnector, instead of a second,
  separate TLS trust story - hence rumqttc now pulls in use-native-tls
  instead of its default rustls stack, so there's one TLS implementation
  in the binary, not two.
- request() publishes and waits (with a timeout) for a report whose
  sequence_id matches, correlated via a shared pending-request table
  that a spawned background task completes as reports arrive - the
  first real tokio::spawn in this crate, flagged as deferred since
  printer/mod.rs's very first doc comment; this is why it was deferred
  until now, and why it's needed now (polling the eventloop has to run
  continuously, independent of whatever call site is waiting).
- publish()/publish_raw() are the fire-and-forget half, for commands
  like gcode_line that only get acknowledged implicitly.

BambuPrinter::connect/send_gcode_line/publish now call the real session
instead of printing what they would do. Verified against 192.0.2.1 (a
reserved, never-routable test address): both AsyncClient/EventLoop pairs
actually attempt a real TCP connection and fail gracefully (network
timeout, not a panic) when nothing answers, and Auto genuinely attempts
both while ForceV1 skips straight to v3.1.1.
This commit is contained in:
octoturge
2026-09-05 21:04:39 +00:00
parent b352fd618d
commit 9643c8b685
6 changed files with 310 additions and 84 deletions
Download Patch File Download Diff File Expand all files Collapse all files
Cargo.toml
+1 -1
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@@ -60,4 +60,4 @@ anyhow = "1"
thiserror = "1"
dotenvy = "0.15"
tokio-serial = { version = "5.5.0", default-features = false }
rumqttc = "0.25.1"
rumqttc = { version = "0.25.1", default-features = false, features = ["use-native-tls"] }
src/printer/bambu.rs
+44 -60
View File
@@ -73,7 +73,11 @@ impl BambuTls {
/// Builds a `native_tls` connector configured for this trust mode:
/// trusting only `ca_bytes()`, or accepting anything for `Insecure`.
fn build_connector(&self) -> anyhow::Result<native_tls::TlsConnector> {
/// `pub(crate)`, not private: `bambu_mqtt.rs` (a sibling module, not a
/// descendant of this one) reuses this exact connector to configure
/// rumqttc's TLS transport, instead of every consumer's TLS trust
/// decisions living in two separate places.
pub(crate) fn build_connector(&self) -> anyhow::Result<native_tls::TlsConnector> {
let mut builder = native_tls::TlsConnector::builder();
// Bambu printer certificates don't carry their LAN IP as a Subject
@@ -182,8 +186,10 @@ pub struct BambuPrinter {
pub sn: String,
tls: BambuTls,
preference: BambuProtocolPreference,
/// `None` until `connect()` succeeds.
version: Option<BambuProtocolVersion>,
/// `None` until `connect()` succeeds. Carries the live MQTT session
/// alongside the protocol version it settled on, since the two are
/// decided together and always used together - see `bambu_mqtt.rs`.
connection: Option<(super::bambu_mqtt::BambuMqttSession, BambuProtocolVersion)>,
}
impl BambuPrinter {
@@ -206,7 +212,7 @@ impl BambuPrinter {
sn: sn.into(),
tls,
preference,
version: None,
connection: None,
}
}
@@ -344,51 +350,33 @@ impl GenericPrinter for BambuPrinter {
&self.base
}
/// Settles `self.version` - forced directly if `preference` says so,
/// otherwise (the real version) attempting an MQTT v5 CONNECT first
/// and falling back to v3.1.1 if the broker's CONNACK rejects that
/// protocol version. No real MQTT client exists yet (still a stub, no
/// different from before), so `Auto` always "detects" v2 for now -
/// the fallback attempt itself is what's left to build.
/// Real, not a stub: opens the MQTT session (see `bambu_mqtt.rs` for
/// `preference`'s `Auto`-tries-v5-then-v3.1.1 fallback) and keeps it -
/// same reasoning as `PrusaSerialPrinter::connect` holding its port
/// open, just an MQTT session instead of a serial port.
async fn connect(&mut self) -> Result<(), PrinterError> {
let mode = match &self.tls {
BambuTls::BundledCa => "bundled Bambu CA",
BambuTls::Custom(_) => "custom CA cert",
BambuTls::Insecure => "no certificate verification",
};
let (session, version) = super::bambu_mqtt::BambuMqttSession::open(
&self.base.host,
&self.access_code,
&self.sn,
&self.tls,
self.preference,
)
.await?;
let version = match self.preference {
BambuProtocolPreference::ForceV1 => BambuProtocolVersion::V1,
BambuProtocolPreference::ForceV2 => BambuProtocolVersion::V2,
BambuProtocolPreference::Auto => {
println!(
"[{}] auto-detecting protocol: trying MQTT v5 first",
self.base.name
);
BambuProtocolVersion::V2
}
};
println!(
"[{}] connecting over MQTTS:8883 ({mode}, {version:?})",
self.base.name
);
self.version = Some(version);
println!("[{}] connected over MQTT ({version:?})", self.base.name);
self.connection = Some((session, version));
Ok(())
}
/// Real: a raw pass-through publish to `device/{sn}/request`, no
/// category envelope opinion - `send_gcode_line` below builds and
/// sends its own properly-wrapped request instead of going through
/// this.
async fn publish(&mut self, payload: String) -> Result<(), PrinterError> {
// TODO: add publishing via MQTT
println!(
"[{}] publishing to device/{}/request: {payload}",
self.base.name, self.sn
);
Ok(())
}
async fn receive(&mut self, payload: String) -> Result<(), PrinterError> {
// TODO: add MQTT response handling
Ok(())
let (session, _) =
self.connection.as_ref().ok_or_else(|| PrinterError(format!("{} is not connected", self.base.name)))?;
session.publish_raw(payload).await
}
/// Same MQTT gcode-injection mechanism regardless of protocol
@@ -423,25 +411,21 @@ impl GenericPrinter for BambuPrinter {
/// which one depends on `self.version`, settled by `connect()` above -
/// instead of a hand-written serde struct: `sequence_id` and the
/// `command` const get filled in by the schema itself, `param` is the
/// one field we actually set. Only the actual MQTT publish to
/// `device/{sn}/request` is still a stub, same as `connect` above.
/// one field we actually set. Real, end to end: publishes over the
/// live MQTT session `connect()` opened, no waiting for a reply -
/// `gcode_line` is fire-and-forget, the printer just executes it.
async fn send_gcode_line(&mut self, gcode_line: String) -> Result<(), PrinterError> {
let version = self
.version
.ok_or_else(|| PrinterError(format!("{} is not connected", self.base.name)))?;
let (session, version) =
self.connection.as_ref().ok_or_else(|| PrinterError(format!("{} is not connected", self.base.name)))?;
let mut print =
continuum_schema_instance::build_instance_from_file(
&get_schema_for_command(
version,
"print".into(),
"gcode_line".into()
)
)
.map_err(|err| PrinterError(format!("failed to build gcode_line request: {err}")))?;
print["param"] = serde_json::Value::String(gcode_line);
let mut body = continuum_schema_instance::build_instance_from_file(&get_schema_for_command(
*version,
"print".into(),
"gcode_line".into(),
))
.map_err(|err| PrinterError(format!("failed to build gcode_line request: {err}")))?;
body["param"] = serde_json::Value::String(gcode_line);
let payload = serde_json::json!({ "print": print }).to_string();
self.publish(payload).await
session.publish("print", &body).await
}
}
src/printer/bambu_mqtt.rs
+264
View File
@@ -0,0 +1,264 @@
//! The real MQTT wiring for Bambu printers - the piece `connect`/
//! `send_gcode_line` in `bambu.rs` used to just stub out with a
//! `println!`. Two things make this more than "call `publish`, get a
//! `String` back":
//!
//! 1. MQTT v3.1.1 (BambuMQTT v1) and MQTT v5 (BambuMQTT v2) are two
//! entirely separate rumqttc client types (`rumqttc::AsyncClient` vs
//! `rumqttc::v5::AsyncClient`) with different event/error types -
//! `BambuMqttClient` is the enum that hides which one a connection
//! ended up using, same pattern as `PrinterHandle` hides which vendor
//! struct you're holding.
//! 2. A response to a published request doesn't come back from that same
//! call - it arrives later, asynchronously, on a *subscription* to
//! `device/{sn}/report`, correlated only by matching `sequence_id`.
//! That needs: a background task continuously polling the connection
//! (rumqttc doesn't do this for you - nothing happens until you poll
//! the `EventLoop` yourself, repeatedly, forever), and a shared table
//! of "who's waiting for which `sequence_id`" that task completes as
//! reports arrive. This is the first real use of `tokio::spawn` in
//! this crate - flagged as deferred since `printer/mod.rs`'s very
//! first doc comment, and this is why: it only makes sense once there's
//! a long-running background job (polling forever) that has to run
//! independently of whatever call site is waiting on a response.
//!
//! Unverified against a live printer (no broker to test against here):
//! the exact `ConnectReturnCode`/error shape a real Bambu printer's
//! embedded broker gives when it doesn't understand MQTT v5's CONNECT at
//! all (rather than a clean version-rejection CONNACK) - `open()` below
//! treats *any* failure of the v5 attempt as "fall back to v3.1.1", not
//! just a precisely-matched version-rejection code, since a broker that
//! can't parse a v5 CONNECT packet may just drop the connection instead
//! of replying with one.
use std::collections::HashMap;
use std::sync::atomic::{AtomicU64, Ordering};
use std::sync::Arc;
use std::time::Duration;
use rumqttc::v5::mqttbytes::v5::Packet as PacketV5;
use rumqttc::v5::mqttbytes::QoS as QoSV5;
use rumqttc::{Event, Packet, QoS, Transport, TlsConfiguration};
use serde_json::Value;
use tokio::sync::{oneshot, Mutex};
use super::bambu::BambuTls;
use super::PrinterError;
use super::BambuProtocolVersion;
/// Requests waiting on a report with a matching `sequence_id`. Shared
/// between whichever call registered one (in `request`) and the
/// background poll task that completes it when the report arrives.
type PendingTable = Arc<Mutex<HashMap<String, oneshot::Sender<Value>>>>;
const REQUEST_TIMEOUT: Duration = Duration::from_secs(10);
enum BambuMqttClient {
V1(rumqttc::AsyncClient),
V2(rumqttc::v5::AsyncClient),
}
/// One live MQTT connection to a Bambu printer - whichever protocol
/// version `open()` settled on.
pub struct BambuMqttSession {
client: BambuMqttClient,
pending: PendingTable,
sn: String,
next_sequence_id: AtomicU64,
}
impl BambuMqttSession {
/// `ForceV1`/`ForceV2` connect with that protocol directly. `Auto`
/// tries v5 first and falls back to v3.1.1 if that attempt fails -
/// see this module's doc comment for why "any failure", not just a
/// precisely-matched version-rejection code.
pub async fn open(
host: &str,
access_code: &str,
sn: &str,
tls: &BambuTls,
preference: super::bambu::BambuProtocolPreference,
) -> Result<(Self, BambuProtocolVersion), PrinterError> {
use super::bambu::BambuProtocolPreference as Pref;
match preference {
Pref::ForceV1 => {
let session = Self::open_v1(host, access_code, sn, tls).await?;
Ok((session, BambuProtocolVersion::V1))
}
Pref::ForceV2 => {
let session = Self::open_v2(host, access_code, sn, tls).await?;
Ok((session, BambuProtocolVersion::V2))
}
Pref::Auto => match Self::open_v2(host, access_code, sn, tls).await {
Ok(session) => Ok((session, BambuProtocolVersion::V2)),
Err(_) => {
let session = Self::open_v1(host, access_code, sn, tls).await?;
Ok((session, BambuProtocolVersion::V1))
}
},
}
}
async fn open_v1(host: &str, access_code: &str, sn: &str, tls: &BambuTls) -> Result<Self, PrinterError> {
let connector = tls.build_connector().map_err(|err| PrinterError(format!("TLS setup failed: {err}")))?;
let mut options = rumqttc::MqttOptions::new(format!("continuum-{sn}"), host, 8883);
options.set_credentials("bblp", access_code);
options.set_transport(Transport::tls_with_config(TlsConfiguration::NativeConnector(connector)));
options.set_keep_alive(Duration::from_secs(30));
let (client, mut event_loop) = rumqttc::AsyncClient::new(options, 10);
client
.subscribe(format!("device/{sn}/report"), QoS::AtMostOnce)
.await
.map_err(|err| PrinterError(format!("subscribe failed: {err}")))?;
// Nothing actually happens on the wire until the eventloop is
// polled - this first poll is what makes the TCP+TLS+CONNECT
// handshake happen, and its result is the only way to know
// whether it worked.
match event_loop.poll().await {
Ok(_) => {}
Err(err) => return Err(PrinterError(format!("MQTT v3.1.1 connect failed: {err}"))),
}
let pending: PendingTable = Arc::new(Mutex::new(HashMap::new()));
tokio::spawn(poll_loop_v1(event_loop, pending.clone()));
Ok(Self { client: BambuMqttClient::V1(client), pending, sn: sn.to_string(), next_sequence_id: AtomicU64::new(1) })
}
async fn open_v2(host: &str, access_code: &str, sn: &str, tls: &BambuTls) -> Result<Self, PrinterError> {
let connector = tls.build_connector().map_err(|err| PrinterError(format!("TLS setup failed: {err}")))?;
let mut options = rumqttc::v5::MqttOptions::new(format!("continuum-{sn}"), host, 8883);
options.set_credentials("bblp", access_code);
options.set_transport(Transport::tls_with_config(TlsConfiguration::NativeConnector(connector)));
options.set_keep_alive(Duration::from_secs(30));
let (client, mut event_loop) = rumqttc::v5::AsyncClient::new(options, 10);
client
.subscribe(format!("device/{sn}/report"), QoSV5::AtMostOnce)
.await
.map_err(|err| PrinterError(format!("subscribe failed: {err}")))?;
match event_loop.poll().await {
Ok(_) => {}
Err(err) => return Err(PrinterError(format!("MQTT v5 connect failed: {err}"))),
}
let pending: PendingTable = Arc::new(Mutex::new(HashMap::new()));
tokio::spawn(poll_loop_v2(event_loop, pending.clone()));
Ok(Self { client: BambuMqttClient::V2(client), pending, sn: sn.to_string(), next_sequence_id: AtomicU64::new(1) })
}
/// Publishes `body` under `device/{sn}/request`, wrapped as
/// `{category: body}` (Bambu's top-level key names the *category*,
/// e.g. "print"/"info" - `body`'s own `command` field says which
/// specific one), and waits up to `REQUEST_TIMEOUT` for a report
/// whose `sequence_id` matches. Overwrites whatever `sequence_id`
/// `body` already had (continuum-schema-instance fills it with an
/// empty placeholder, since it has no way to know a real one) with a
/// fresh one from this session's own counter.
pub async fn request(&self, category: &str, mut body: Value) -> Result<Value, PrinterError> {
let sequence_id = self.next_sequence_id.fetch_add(1, Ordering::Relaxed).to_string();
body["sequence_id"] = Value::String(sequence_id.clone());
let (tx, rx) = oneshot::channel();
self.pending.lock().await.insert(sequence_id.clone(), tx);
if let Err(err) = self.publish(category, &body).await {
self.pending.lock().await.remove(&sequence_id);
return Err(err);
}
match tokio::time::timeout(REQUEST_TIMEOUT, rx).await {
Ok(Ok(response)) => Ok(response),
Ok(Err(_)) => Err(PrinterError(format!("{} closed before replying", self.sn))),
Err(_) => {
self.pending.lock().await.remove(&sequence_id);
Err(PrinterError(format!("{} did not reply within {REQUEST_TIMEOUT:?}", self.sn)))
}
}
}
/// Publishes `body` under `device/{sn}/request`, wrapped as
/// `{category: body}`, without waiting for a reply - for commands
/// like `gcode_line` that only get acknowledged implicitly (the
/// printer just executes it), not answered directly.
pub async fn publish(&self, category: &str, body: &Value) -> Result<(), PrinterError> {
self.publish_raw(serde_json::json!({ category: body }).to_string()).await
}
/// Publishes an already-serialized payload under `device/{sn}/request`
/// as-is, with no category wrapping - the low-level primitive both
/// `publish` above and `GenericPrinter::publish` (a raw pass-through,
/// no envelope opinion at all) are built on.
pub async fn publish_raw(&self, payload: String) -> Result<(), PrinterError> {
let topic = format!("device/{}/request", self.sn);
match &self.client {
BambuMqttClient::V1(client) => client
.publish(topic, QoS::AtLeastOnce, false, payload)
.await
.map_err(|err| PrinterError(format!("publish failed: {err}"))),
BambuMqttClient::V2(client) => client
.publish(topic, QoSV5::AtLeastOnce, false, payload)
.await
.map_err(|err| PrinterError(format!("publish failed: {err}"))),
}
}
}
/// Runs forever, polling the v3.1.1 eventloop and completing pending
/// requests as matching reports arrive. Ends (silently) once the
/// connection is gone for good - dropping the `BambuMqttSession` drops
/// its `AsyncClient`, which is what eventually makes that happen.
async fn poll_loop_v1(mut event_loop: rumqttc::EventLoop, pending: PendingTable) {
loop {
match event_loop.poll().await {
Ok(Event::Incoming(Packet::Publish(publish))) => {
complete_pending(&pending, &publish.payload).await;
}
Ok(_) => {}
Err(_) => return,
}
}
}
async fn poll_loop_v2(mut event_loop: rumqttc::v5::EventLoop, pending: PendingTable) {
loop {
match event_loop.poll().await {
Ok(rumqttc::v5::Event::Incoming(PacketV5::Publish(publish))) => {
complete_pending(&pending, &publish.payload).await;
}
Ok(_) => {}
Err(_) => return,
}
}
}
/// Parses an incoming report and, if its `sequence_id` matches something
/// `request` is waiting on, hands it the parsed JSON. A report with no
/// `sequence_id`, or one nothing's waiting on (an unsolicited status
/// push, not a reply to anything), is silently ignored - most Bambu
/// reports aren't replies to a specific request at all.
async fn complete_pending(pending: &PendingTable, payload: &[u8]) {
let Ok(value) = serde_json::from_slice::<Value>(payload) else { return };
let Some(sequence_id) = find_sequence_id(&value) else { return };
if let Some(sender) = pending.lock().await.remove(&sequence_id) {
let _ = sender.send(value);
}
}
/// A report is `{category: {"sequence_id": "...", ...}}` - one key, same
/// shape as a request. Look inside whichever single category key is
/// present rather than requiring the caller to already know it.
fn find_sequence_id(report: &Value) -> Option<String> {
let object = report.as_object()?;
let (_, category_body) = object.iter().next()?;
category_body.get("sequence_id")?.as_str().map(str::to_string)
}
src/printer/klipper.rs
-4
View File
@@ -34,10 +34,6 @@ impl GenericPrinter for KlipperPrinter {
Ok(())
}
async fn receive(&mut self, payload: String) -> Result<(), PrinterError> {
// TODO: add HTTP response handling
Ok(())
}
/// OVERRIDE: Moonraker's own **hypothetical** native API, not gcode injection - no
/// percent-to-PWM conversion needed since it already takes a
/// percentage directly. Real version:
src/printer/mod.rs
+1 -10
View File
@@ -28,6 +28,7 @@
mod bambu;
mod bambu_commands;
mod bambu_mqtt;
mod klipper;
mod marlin_serial;
mod prusa;
@@ -73,7 +74,6 @@ pub trait GenericPrinter {
async fn publish(&mut self, payload: String) -> Result<(), PrinterError>;
async fn receive(&mut self, payload: String) -> Result<(), PrinterError>;
/// REQUIRED, no default body: `percent` is 0-100, but how it actually
/// gets sent - an MQTT gcode-injection command, a REST call, raw bytes
@@ -159,15 +159,6 @@ impl GenericPrinter for PrinterHandle {
}
}
async fn receive(&mut self, payload: String) -> Result<(), PrinterError> {
match self {
PrinterHandle::Bambu(p) => p.receive(payload).await,
PrinterHandle::PrusaLink(p) => p.receive(payload).await,
PrinterHandle::PrusaSerial(p) => p.receive(payload).await,
PrinterHandle::Klipper(p) => p.receive(payload).await,
}
}
async fn set_fan_speed(&mut self, percent: u8) -> Result<(), PrinterError> {
match self {
PrinterHandle::Bambu(p) => p.set_fan_speed(percent).await,
src/printer/prusa.rs
-9
View File
@@ -34,11 +34,6 @@ impl GenericPrinter for PrusaLinkPrinter {
Ok(())
}
async fn receive(&mut self, payload: String) -> Result<(), PrinterError> {
// TODO: add HTTP response handling
Ok(())
}
/// OVERRIDE: gcode via PrusaLink's command-injection endpoint - same
/// underlying M106 as Bambu, reusing the shared percent->PWM
/// conversion, but sent over HTTP instead of MQTT.
@@ -110,10 +105,6 @@ impl GenericPrinter for PrusaSerialPrinter {
Ok(())
}
async fn receive(&mut self, payload: String) -> Result<(), PrinterError> {
// TODO: add Serial response handling
Ok(())
}
/// OVERRIDE: same gcode as PrusaLink (still M106, still the shared
/// conversion), but sent through `send_gcode_line` below instead of a
/// separate transport - serial only has the one way to talk to the