Mercurial > prosody-modules
view mod_pubsub_mqtt/mqtt.lib.lua @ 4651:8231774f5bfd
mod_cloud_notify_encrypted: Ensure body substring remains valid UTF-8
The `body:sub()` call risks splitting the string in the middle of a
multi-byte UTF-8 sequence. This should have been caught by util.stanza
validation, but that would have caused some havoc, at the very least causing
the notification to not be sent.
There have been no reports of this happening. Likely because this module
isn't widely deployed among users with languages that use many longer UTF-8
sequences.
The util.encodings.utf8.valid() function is O(n) where only the last
sequence really needs to be checked, but it's in C and expected to be fast.
author | Kim Alvefur <zash@zash.se> |
---|---|
date | Sun, 22 Aug 2021 13:22:59 +0200 |
parents | 7dbde05b48a9 |
children | d2a84e6aed2b |
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local bit = require "bit"; local stream_mt = {}; stream_mt.__index = stream_mt; function stream_mt:read_bytes(n_bytes) module:log("debug", "Reading %d bytes... (buffer: %d)", n_bytes, #self.buffer); local data = self.buffer; if not data then module:log("debug", "No data, pausing."); data = coroutine.yield(); module:log("debug", "Have %d bytes of data now (want %d)", #data, n_bytes); end if #data >= n_bytes then data, self.buffer = data:sub(1, n_bytes), data:sub(n_bytes+1); elseif #data < n_bytes then module:log("debug", "Not enough data (only %d bytes out of %d), pausing.", #data, n_bytes); self.buffer = data..coroutine.yield(); module:log("debug", "Now we have %d bytes, reading...", #data); return self:read_bytes(n_bytes); end module:log("debug", "Returning %d bytes (buffer: %d)", #data, #self.buffer); return data; end function stream_mt:read_string() local len1, len2 = self:read_bytes(2):byte(1,2); local len = bit.lshift(len1, 8) + len2; return self:read_bytes(len), len+2; end local packet_type_codes = { "connect", "connack", "publish", "puback", "pubrec", "pubrel", "pubcomp", "subscribe", "subak", "unsubscribe", "unsuback", "pingreq", "pingresp", "disconnect" }; function stream_mt:read_packet() local packet = {}; local header = self:read_bytes(1):byte(); packet.type = packet_type_codes[bit.rshift(bit.band(header, 0xf0), 4)]; packet.dup = bit.band(header, 0x08) == 0x08; packet.qos = bit.rshift(bit.band(header, 0x06), 1); packet.retain = bit.band(header, 0x01) == 0x01; -- Get length local length, multiplier = 0, 1; repeat local digit = self:read_bytes(1):byte(); length = length + bit.band(digit, 0x7f)*multiplier; multiplier = multiplier*128; until bit.band(digit, 0x80) == 0; packet.length = length; if packet.type == "connect" then if self:read_string() ~= "MQIsdp" then module:log("warn", "Unexpected packet signature!"); packet.type = nil; -- Invalid packet else packet.version = self:read_bytes(1):byte(); packet.connect_flags = self:read_bytes(1):byte(); packet.keepalive_timer = self:read_bytes(1):byte(); length = length - 11; end elseif packet.type == "publish" then packet.topic = self:read_string(); length = length - (#packet.topic+2); if packet.qos == 1 or packet.qos == 2 then packet.id = self:read_bytes(2); length = length - 2; end elseif packet.type == "subscribe" then if packet.qos == 1 or packet.qos == 2 then packet.id = self:read_bytes(2); length = length - 2; end local topics = {}; while length > 0 do local topic, len = self:read_string(); table.insert(topics, topic); self:read_bytes(1); -- QoS not used length = length - (len+1); end packet.topics = topics; end if length > 0 then packet.data = self:read_bytes(length); end return packet; end local function new_parser(self) return coroutine.wrap(function (data) self.buffer = data; while true do data = coroutine.yield(self:read_packet()); module:log("debug", "Parser: %d new bytes", #data); self.buffer = (self.buffer or "")..data; end end); end function stream_mt:feed(data) module:log("debug", "Feeding %d bytes", #data); local packets = {}; local packet = self.parser(data); while packet do module:log("debug", "Received packet"); table.insert(packets, packet); packet = self.parser(""); end module:log("debug", "Returning %d packets", #packets); return packets; end local function new_stream() local stream = setmetatable({}, stream_mt); stream.parser = new_parser(stream); return stream; end local function serialize_packet(packet) local type_num = 0; for i, v in ipairs(packet_type_codes) do -- FIXME: I'm so tired right now. if v == packet.type then type_num = i; break; end end local header = string.char(bit.lshift(type_num, 4)); if packet.type == "publish" then local topic = packet.topic or ""; packet.data = string.char(bit.band(#topic, 0xff00), bit.band(#topic, 0x00ff))..topic..packet.data; elseif packet.type == "suback" then local t = {}; for _, topic in ipairs(packet.topics) do table.insert(t, string.char(bit.band(#topic, 0xff00), bit.band(#topic, 0x00ff))..topic.."\000"); end packet.data = table.concat(t); end -- Get length local length = #(packet.data or ""); repeat local digit = length%128; length = math.floor(length/128); if length > 0 then digit = bit.bor(digit, 0x80); end header = header..string.char(digit); -- FIXME: ... until length <= 0; return header..(packet.data or ""); end return { new_stream = new_stream; serialize_packet = serialize_packet; };