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Fix MQTT v5.0 "beyond size" error in PUBACK parsing #53

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Merged
xHasKx merged 2 commits into from
Mar 27, 2026
Merged

Fix MQTT v5.0 "beyond size" error in PUBACK parsing #53

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4cc5237
fixed PUBACK parsing implementation gap
haukepribnow Mar 25, 2026
0895b9d
Merge branch 'v5ackfix' into master
haukepribnow Mar 25, 2026
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17 changes: 12 additions & 5 deletions mqtt/protocol5.lua
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Original file line number Diff line number Diff line change
Expand Up @@ -980,24 +980,31 @@ local function parse_packet_puback(ptype, flags, input)
return false, packet_type[ptype]..": unexpected flags value: "..flags
end
local read_data = input.read_func

-- DOC: 3.4.2 PUBACK Variable Header
-- Bytes 1 & 2: Packet Identifier
local packet_id, err = parse_uint16(read_data)
if not packet_id then
return false, packet_type[ptype]..": failed to parse packet_id: "..err
end
local packet = setmetatable({type=ptype, packet_id=packet_id, rc=0, properties={}, user_properties={}}, packet_mt)
-- If Remaining Length > 2, we have at least a Reason Code
if input.available > 0 then
-- DOC: 3.4.2.1 PUBACK Reason Code
-- DOC: 3.4.2.1 PUBACK Reason Code (Byte 3)
local rc, ok
rc, err = parse_uint8(read_data)
if not rc then
return false, packet_type[ptype]..": failed to parse rc: "..err
end
packet.rc = rc
-- DOC: 3.4.2.2 PUBACK Properties
ok, err = parse_properties(ptype, read_data, input, packet)
if not ok then
return false, packet_type[ptype]..": failed to parse packet properties: "..err

-- DOC: 3.4.2.2.1 If Remaining Length > 3, we have a Property Length field (Byte 4)
if input.available > 0 then
-- DOC: 3.4.2.2 PUBACK Properties
ok, err = parse_properties(ptype, read_data, input, packet)
if not ok then
return false, packet_type[ptype]..": failed to parse packet properties: "..err
end
end
end
return packet
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