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Handle UTF-16 correctly in Wireshark dissector

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sfan5 2021-01-29 16:08:49 +01:00
parent 674d67f312
commit 9388c23e86
1 changed files with 2 additions and 31 deletions
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33
util/wireshark/minetest.lua
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@ -299,7 +299,7 @@ do
t:add(f_length, buffer(2,2)) t:add(f_length, buffer(2,2))
local textlen = buffer(2,2):uint() local textlen = buffer(2,2):uint()
if minetest_check_length(buffer, 4 + textlen*2, t) then if minetest_check_length(buffer, 4 + textlen*2, t) then
t:add(f_message, minetest_convert_utf16(buffer(4, textlen*2), "Converted chat message")) t:add(f_message, buffer(4, textlen*2), buffer(4, textlen*2):ustring())
end end
end end
} }
@ -1379,35 +1379,6 @@ function minetest_check_length(tvb, min_len, t)
end end
end end
-- Takes a Tvb or TvbRange (i.e. part of a packet) that
-- contains a UTF-16 string and returns a TvbRange containing
-- string converted to ASCII. Any characters outside the range
-- 0x20 to 0x7e are replaced by a question mark.
-- Parameter: tvb: Tvb or TvbRange that contains the UTF-16 data
-- Parameter: name: will be the name of the newly created Tvb.
-- Returns: New TvbRange containing the ASCII string.
-- TODO: Handle surrogates (should only produce one question mark)
-- TODO: Remove this when Wireshark supports UTF-16 strings natively.
function minetest_convert_utf16(tvb, name)
local hex, pos, char
hex = ""
for pos = 0, tvb:len() - 2, 2 do
char = tvb(pos, 2):uint()
if (char >= 0x20 and char <= 0x7e) or char == 0x0a then
hex = hex .. string.format(" %02x", char)
else
hex = hex .. " 3F"
end
end
if hex == "" then
-- This is a hack to avoid a failed assertion in tvbuff.c
-- (function: ensure_contiguous_no_exception)
return ByteArray.new("00"):tvb(name):range(0,0)
else
return ByteArray.new(hex):tvb(name):range()
end
end
-- Decodes a variable-length string as ASCII text -- Decodes a variable-length string as ASCII text
-- t_textlen, t_text should be the ProtoFields created by minetest_field_helper -- t_textlen, t_text should be the ProtoFields created by minetest_field_helper
-- alternatively t_text can be a ProtoField.string and t_textlen can be nil -- alternatively t_text can be a ProtoField.string and t_textlen can be nil
@ -1438,7 +1409,7 @@ function minetest_decode_helper_utf16(tvb, t, lentype, offset, f_textlen, f_text
end end
local textlen = tvb(offset, n):uint() * 2 local textlen = tvb(offset, n):uint() * 2
if minetest_check_length(tvb, offset + n + textlen, t) then if minetest_check_length(tvb, offset + n + textlen, t) then
t:add(f_text, minetest_convert_utf16(tvb(offset + n, textlen), "UTF-16 text")) t:add(f_text, tvb(offset + n, textlen), tvb(offset + n, textlen):ustring())
return offset + n + textlen return offset + n + textlen
end end
end end