Files
bambuddy/backend/app/services/virtual_printer/bind_server.py
T
maziggy e5b2cee2f1 Fix VP bind server rejecting TLS connections on port 3002 (#559)
BambuStudio uses TLS on port 3002 for certain printer models (e.g. A1
  Mini / N1). The bind server only spoke plain TCP on both ports, so the
  TLS ClientHello was rejected as "invalid frame" and the slicer could
  never discover or connect to the virtual printer.

  Port 3002 now uses TLS (reusing the VP's existing certificate), port
  3000 remains plain TCP. Also updated proxy-mode to use TLSProxy for
  the port 3002 bind proxy instead of raw TCPProxy.
2026-03-01 12:43:13 +01:00

242 lines
8.5 KiB
Python

"""Bind/detect server for virtual printer discovery (ports 3000 + 3002).
Bambu slicers (BambuStudio, OrcaSlicer) connect to a printer on port 3000
or 3002 to perform the "bind with access code" handshake before using
MQTT/FTP.
Port 3000: plain TCP (legacy / some printer models).
Port 3002: TLS (newer firmware, e.g. A1 Mini 01.07.x).
Protocol (same on both ports, only transport differs):
- Framing: 0xA5A5 + uint16_le(total_msg_size) + JSON payload + 0xA7A7
- Slicer sends: {"login":{"command":"detect","sequence_id":"20000"}}
- Printer replies: {"login":{"bind":"free","command":"detect","connect":"lan",
"dev_cap":1,"id":"<serial>","model":"<model>","name":"<name>",
"sequence_id":<int>,"version":"<firmware>"}}
- Connection closes after one exchange.
"""
import asyncio
import json
import logging
import ssl
import struct
from pathlib import Path
logger = logging.getLogger(__name__)
BIND_PORT_PLAIN = 3000
BIND_PORT_TLS = 3002
BIND_PORTS = [BIND_PORT_PLAIN, BIND_PORT_TLS]
FRAME_HEADER = b"\xa5\xa5"
FRAME_TRAILER = b"\xa7\xa7"
HEADER_SIZE = 4 # 2 bytes magic + 2 bytes length
TRAILER_SIZE = 2
class BindServer:
"""Responds to slicer bind/detect requests on ports 3000 and 3002.
In server mode, Bambuddy IS the printer — it responds with its own
identity so the slicer can discover and bind to it.
Port 3000 is plain TCP, port 3002 is TLS. BambuStudio chooses which
port to use based on the printer model discovered via SSDP.
"""
def __init__(
self,
serial: str,
model: str,
name: str,
version: str = "01.00.00.00",
bind_address: str = "0.0.0.0", # nosec B104
cert_path: Path | None = None,
key_path: Path | None = None,
):
self.serial = serial
self.model = model
self.name = name
self.version = version
self.bind_address = bind_address
self.cert_path = cert_path
self.key_path = key_path
self._servers: list[asyncio.Server] = []
self._running = False
def _create_tls_context(self) -> ssl.SSLContext | None:
"""Create SSL context for the TLS bind port (3002)."""
if not self.cert_path or not self.key_path:
return None
ctx = ssl.SSLContext(ssl.PROTOCOL_TLS_SERVER)
ctx.load_cert_chain(str(self.cert_path), str(self.key_path))
ctx.minimum_version = ssl.TLSVersion.TLSv1_2
ctx.verify_mode = ssl.CERT_NONE
return ctx
async def start(self) -> None:
"""Start the bind server on ports 3000 (plain) and 3002 (TLS)."""
if self._running:
return
self._running = True
tls_ctx = self._create_tls_context()
if not tls_ctx:
logger.warning("Bind server: no TLS cert provided, port %s will be plain TCP", BIND_PORT_TLS)
logger.info(
"Starting bind server on ports %s (serial=%s, model=%s, tls=%s)",
BIND_PORTS,
self.serial,
self.model,
tls_ctx is not None,
)
try:
for port in BIND_PORTS:
use_tls = port == BIND_PORT_TLS and tls_ctx is not None
try:
server = await asyncio.start_server(
self._handle_client,
self.bind_address,
port,
ssl=tls_ctx if use_tls else None,
)
self._servers.append(server)
logger.info(
"Bind server listening on %s:%s (%s)",
self.bind_address,
port,
"TLS" if use_tls else "plain",
)
except OSError as e:
if e.errno == 98:
logger.warning("Bind server port %s already in use, skipping", port)
elif e.errno == 13:
logger.warning("Bind server: cannot bind to port %s (permission denied), skipping", port)
else:
logger.warning("Bind server: failed to bind port %s: %s", port, e)
if not self._servers:
logger.error("Bind server: could not bind to any port")
return
# Serve all successfully bound ports
await asyncio.gather(*(s.serve_forever() for s in self._servers))
except asyncio.CancelledError:
logger.debug("Bind server task cancelled")
except Exception as e:
logger.error("Bind server error: %s", e)
finally:
await self.stop()
async def stop(self) -> None:
"""Stop the bind server."""
logger.info("Stopping bind server")
self._running = False
for server in self._servers:
try:
server.close()
await server.wait_closed()
except OSError as e:
logger.debug("Error closing bind server: %s", e)
self._servers = []
async def _handle_client(
self,
reader: asyncio.StreamReader,
writer: asyncio.StreamWriter,
) -> None:
"""Handle a single bind/detect request from a slicer."""
peername = writer.get_extra_info("peername")
client_id = f"{peername[0]}:{peername[1]}" if peername else "unknown"
logger.info("Bind server: client connected from %s", client_id)
try:
# Read the framed message (timeout after 10s)
data = await asyncio.wait_for(reader.read(4096), timeout=10.0)
if not data:
return
# Parse the request
request = self._parse_frame(data)
if request is None:
logger.warning("Bind server: invalid frame from %s", client_id)
return
logger.info("Bind server: received from %s: %s", client_id, request)
# Check if this is a detect command
login = request.get("login", {})
if not isinstance(login, dict) or login.get("command") != "detect":
logger.warning("Bind server: unexpected command from %s: %s", client_id, request)
return
# Build response
response = {
"login": {
"bind": "free",
"command": "detect",
"connect": "lan",
"dev_cap": 1,
"id": self.serial,
"model": self.model,
"name": self.name,
"sequence_id": 3021,
"version": self.version,
}
}
frame = self._build_frame(response)
writer.write(frame)
await writer.drain()
logger.info("Bind server: sent detect response to %s (serial=%s)", client_id, self.serial)
except TimeoutError:
logger.debug("Bind server: timeout waiting for data from %s", client_id)
except Exception as e:
logger.error("Bind server: error handling %s: %s", client_id, e)
finally:
try:
writer.close()
await writer.wait_closed()
except OSError:
pass
logger.debug("Bind server: client %s disconnected", client_id)
def _parse_frame(self, data: bytes) -> dict | None:
"""Parse a framed message: 0xA5A5 + len(u16le) + JSON + 0xA7A7."""
if len(data) < HEADER_SIZE + TRAILER_SIZE:
return None
if data[:2] != FRAME_HEADER:
return None
if data[-2:] != FRAME_TRAILER:
return None
# Length field is total message size (header + json + trailer)
total_len = struct.unpack_from("<H", data, 2)[0]
if total_len != len(data):
logger.debug("Bind frame length mismatch: header says %d, got %d", total_len, len(data))
# JSON payload is between header and trailer
json_bytes = data[HEADER_SIZE:-TRAILER_SIZE]
try:
return json.loads(json_bytes)
except (json.JSONDecodeError, UnicodeDecodeError) as e:
logger.warning("Bind server: failed to parse JSON: %s", e)
return None
def _build_frame(self, payload: dict) -> bytes:
"""Build a framed message: 0xA5A5 + len(u16le) + JSON + 0xA7A7."""
json_bytes = json.dumps(payload, separators=(",", ":")).encode("utf-8")
total_len = HEADER_SIZE + len(json_bytes) + TRAILER_SIZE
header = FRAME_HEADER + struct.pack("<H", total_len)
return header + json_bytes + FRAME_TRAILER