79 lines
2.4 KiB
Python
79 lines
2.4 KiB
Python
import socket
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import struct
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class SimpleMQTT:
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def __init__(self, host, port=1883):
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self.host = host
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self.port = port
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self.sock = None
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def connect(self, client_id, username=None, password=None):
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addr_info = socket.getaddrinfo(self.host, self.port)
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addr = addr_info[0][-1]
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self.sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
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self.sock.connect(addr)
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# Flags: Clean session (bit 1) + optional credentials
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flags = 0x02
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if username:
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flags |= 0x80
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if password:
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flags |= 0x40
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# Variable header: Protocol Name (MQTT) + Level (4) + Flags + KeepAlive (60s)
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var_header = bytearray(
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[0x00, 0x04, ord("M"), ord("Q"), ord("T"), ord("T"), 0x04, flags, 0x00, 0x3C]
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)
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payload = bytearray()
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payload.extend(self._encode_str(client_id))
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if username:
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payload.extend(self._encode_str(username))
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if password:
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payload.extend(self._encode_str(password))
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body = var_header + payload
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packet = bytearray([0x10]) + self._encode_len(len(body)) + body
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self.sock.write(packet)
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# Read CONNACK (4 bytes: 0x20, 0x02, ack_flags, return_code)
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resp = self.sock.read(4)
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if not resp or resp[0] != 0x20 or resp[3] != 0x00:
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code = resp[3] if resp and len(resp) >= 4 else "nil"
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raise RuntimeError(f"MQTT connection failed: code {code}")
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def publish(self, topic, payload, retain=False):
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cmd = 0x30 | (0x01 if retain else 0x00)
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if isinstance(payload, str):
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payload = payload.encode("utf-8")
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body = self._encode_str(topic) + payload
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packet = bytearray([cmd]) + self._encode_len(len(body)) + body
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self.sock.write(packet)
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def disconnect(self):
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try:
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if self.sock:
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self.sock.write(bytearray([0xE0, 0x00]))
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self.sock.close()
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except Exception:
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pass
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finally:
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self.sock = None
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def _encode_str(self, s):
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raw = s.encode("utf-8")
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return struct.pack("!H", len(raw)) + raw
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def _encode_len(self, length):
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encoded = bytearray()
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while True:
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digit = length % 128
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length //= 128
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if length > 0:
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digit |= 0x80
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encoded.append(digit)
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if length == 0:
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break
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return encoded
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