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import binascii
import struct
from typing import Tuple
def dump_packet(prefix: str, data: bytes) -> None:
try:
data = to_string(data)
print(prefix, ": ", data, sep="")
except struct.error:
data = binascii.b2a_hex(data).decode('utf8')
print(prefix, " (not decoded): 0x", data, sep="")
def remaining_length(packet: bytes) -> Tuple[bytes, int]:
l = min(5, len(packet)) # noqa: E741
all_bytes = struct.unpack("!" + "B" * l, packet[:l])
mult = 1
rl = 0
for i in range(1, l - 1):
byte = all_bytes[i]
rl += (byte & 127) * mult
mult *= 128
if byte & 128 == 0:
packet = packet[i + 1:]
break
return (packet, rl)
def to_hex_string(packet: bytes) -> str:
if not packet:
return ""
s = ""
while len(packet) > 0:
packet0 = struct.unpack("!B", packet[0])
s = s+hex(packet0[0]) + " "
packet = packet[1:]
return s
def to_string(packet: bytes) -> str:
if not packet:
return ""
packet0 = struct.unpack("!B%ds" % (len(packet)-1), bytes(packet))
packet0 = packet0[0]
cmd = packet0 & 0xF0
if cmd == 0x00:
# Reserved
return "0x00"
elif cmd == 0x10:
# CONNECT
(packet, rl) = remaining_length(packet)
pack_format = "!H" + str(len(packet) - 2) + 's'
(slen, packet) = struct.unpack(pack_format, packet)
pack_format = "!" + str(slen) + 'sBBH' + str(len(packet) - slen - 4) + 's'
(protocol, proto_ver, flags, keepalive, packet) = struct.unpack(pack_format, packet)
kind = ("clean-session" if flags & 2 else "durable")
s = f"CONNECT, proto={protocol}{proto_ver}, keepalive={keepalive}, {kind}"
pack_format = "!H" + str(len(packet) - 2) + 's'
(slen, packet) = struct.unpack(pack_format, packet)
pack_format = "!" + str(slen) + 's' + str(len(packet) - slen) + 's'
(client_id, packet) = struct.unpack(pack_format, packet)
s = s + ", id=" + str(client_id)
if flags & 4:
pack_format = "!H" + str(len(packet) - 2) + 's'
(slen, packet) = struct.unpack(pack_format, packet)
pack_format = "!" + str(slen) + 's' + str(len(packet) - slen) + 's'
(will_topic, packet) = struct.unpack(pack_format, packet)
s = s + ", will-topic=" + str(will_topic)
pack_format = "!H" + str(len(packet) - 2) + 's'
(slen, packet) = struct.unpack(pack_format, packet)
pack_format = "!" + str(slen) + 's' + str(len(packet) - slen) + 's'
(will_message, packet) = struct.unpack(pack_format, packet)
s = s + ", will-message=" + will_message
s = s + ", will-qos=" + str((flags & 24) >> 3)
s = s + ", will-retain=" + str((flags & 32) >> 5)
if flags & 128:
pack_format = "!H" + str(len(packet) - 2) + 's'
(slen, packet) = struct.unpack(pack_format, packet)
pack_format = "!" + str(slen) + 's' + str(len(packet) - slen) + 's'
(username, packet) = struct.unpack(pack_format, packet)
s = s + ", username=" + str(username)
if flags & 64:
pack_format = "!H" + str(len(packet) - 2) + 's'
(slen, packet) = struct.unpack(pack_format, packet)
pack_format = "!" + str(slen) + 's' + str(len(packet) - slen) + 's'
(password, packet) = struct.unpack(pack_format, packet)
s = s + ", password=" + str(password)
if flags & 1:
s = s + ", reserved=1"
return s
elif cmd == 0x20:
# CONNACK
if len(packet) == 4:
(cmd, rl, resv, rc) = struct.unpack('!BBBB', packet)
return "CONNACK, rl="+str(rl)+", res="+str(resv)+", rc="+str(rc)
elif len(packet) == 5:
(cmd, rl, flags, reason_code, proplen) = struct.unpack('!BBBBB', packet)
return "CONNACK, rl="+str(rl)+", flags="+str(flags)+", rc="+str(reason_code)+", proplen="+str(proplen)
else:
return "CONNACK, (not decoded)"
elif cmd == 0x30:
# PUBLISH
dup = (packet0 & 0x08) >> 3
qos = (packet0 & 0x06) >> 1
retain = (packet0 & 0x01)
(packet, rl) = remaining_length(packet)
pack_format = "!H" + str(len(packet) - 2) + 's'
(tlen, packet) = struct.unpack(pack_format, packet)
pack_format = "!" + str(tlen) + 's' + str(len(packet) - tlen) + 's'
(topic, packet) = struct.unpack(pack_format, packet)
s = "PUBLISH, rl=" + str(rl) + ", topic=" + str(topic) + ", qos=" + str(qos) + ", retain=" + str(retain) + ", dup=" + str(dup)
if qos > 0:
pack_format = "!H" + str(len(packet) - 2) + 's'
(mid, packet) = struct.unpack(pack_format, packet)
s = s + ", mid=" + str(mid)
s = s + ", payload=" + str(packet)
return s
elif cmd == 0x40:
# PUBACK
if len(packet) == 5:
(cmd, rl, mid, reason_code) = struct.unpack('!BBHB', packet)
return "PUBACK, rl="+str(rl)+", mid="+str(mid)+", reason_code="+str(reason_code)
else:
(cmd, rl, mid) = struct.unpack('!BBH', packet)
return "PUBACK, rl="+str(rl)+", mid="+str(mid)
elif cmd == 0x50:
# PUBREC
if len(packet) == 5:
(cmd, rl, mid, reason_code) = struct.unpack('!BBHB', packet)
return "PUBREC, rl="+str(rl)+", mid="+str(mid)+", reason_code="+str(reason_code)
else:
(cmd, rl, mid) = struct.unpack('!BBH', packet)
return "PUBREC, rl="+str(rl)+", mid="+str(mid)
elif cmd == 0x60:
# PUBREL
dup = (packet0 & 0x08) >> 3
(cmd, rl, mid) = struct.unpack('!BBH', packet)
return "PUBREL, rl=" + str(rl) + ", mid=" + str(mid) + ", dup=" + str(dup)
elif cmd == 0x70:
# PUBCOMP
(cmd, rl, mid) = struct.unpack('!BBH', packet)
return "PUBCOMP, rl=" + str(rl) + ", mid=" + str(mid)
elif cmd == 0x80:
# SUBSCRIBE
(packet, rl) = remaining_length(packet)
pack_format = "!H" + str(len(packet) - 2) + 's'
(mid, packet) = struct.unpack(pack_format, packet)
s = "SUBSCRIBE, rl=" + str(rl) + ", mid=" + str(mid)
topic_index = 0
while len(packet) > 0:
pack_format = "!H" + str(len(packet) - 2) + 's'
(tlen, packet) = struct.unpack(pack_format, packet)
pack_format = "!" + str(tlen) + 'sB' + str(len(packet) - tlen - 1) + 's'
(topic, qos, packet) = struct.unpack(pack_format, packet)
s = s + ", topic" + str(topic_index) + "=" + str(topic) + "," + str(qos)
return s
elif cmd == 0x90:
# SUBACK
(packet, rl) = remaining_length(packet)
pack_format = "!H" + str(len(packet) - 2) + 's'
(mid, packet) = struct.unpack(pack_format, packet)
pack_format = "!" + "B" * len(packet)
granted_qos = struct.unpack(pack_format, packet)
s = "SUBACK, rl=" + str(rl) + ", mid=" + str(mid) + ", granted_qos=" + str(granted_qos[0])
for i in range(1, len(granted_qos) - 1):
s = s + ", " + str(granted_qos[i])
return s
elif cmd == 0xA0:
# UNSUBSCRIBE
(packet, rl) = remaining_length(packet)
pack_format = "!H" + str(len(packet) - 2) + 's'
(mid, packet) = struct.unpack(pack_format, packet)
s = "UNSUBSCRIBE, rl=" + str(rl) + ", mid=" + str(mid)
topic_index = 0
while len(packet) > 0:
pack_format = "!H" + str(len(packet) - 2) + 's'
(tlen, packet) = struct.unpack(pack_format, packet)
pack_format = "!" + str(tlen) + 's' + str(len(packet) - tlen) + 's'
(topic, packet) = struct.unpack(pack_format, packet)
s = s + ", topic" + str(topic_index) + "=" + str(topic)
return s
elif cmd == 0xB0:
# UNSUBACK
(cmd, rl, mid) = struct.unpack('!BBH', packet)
return "UNSUBACK, rl=" + str(rl) + ", mid=" + str(mid)
elif cmd == 0xC0:
# PINGREQ
(cmd, rl) = struct.unpack('!BB', packet)
return "PINGREQ, rl=" + str(rl)
elif cmd == 0xD0:
# PINGRESP
(cmd, rl) = struct.unpack('!BB', packet)
return "PINGRESP, rl=" + str(rl)
elif cmd == 0xE0:
# DISCONNECT
if len(packet) == 3:
(cmd, rl, reason_code) = struct.unpack('!BBB', packet)
return "DISCONNECT, rl="+str(rl)+", reason_code="+str(reason_code)
else:
(cmd, rl) = struct.unpack('!BB', packet)
return "DISCONNECT, rl="+str(rl)
elif cmd == 0xF0:
# AUTH
(cmd, rl) = struct.unpack('!BB', packet)
return "AUTH, rl="+str(rl)
raise ValueError(f"Unknown packet type {cmd}")
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