diff options
| -rw-r--r-- | lua/file-zip.lua | 14 |
1 files changed, 7 insertions, 7 deletions
diff --git a/lua/file-zip.lua b/lua/file-zip.lua index b50e62b..dcfb165 100644 --- a/lua/file-zip.lua +++ b/lua/file-zip.lua @@ -192,22 +192,22 @@ end -- Returns the length of the data and the length of the data descriptor. local function find_data_desc(tvb) local dd_offset = 0 - local length = tvb:len() + local data = tvb:raw(tvb:offset()) -- Scans (byte for byte) for the size field and try to confirm the validity -- of this length field. It might still have a false positive, but at least - -- it allows for a linear search. - while dd_offset + 8 < length do + -- it allows for a linear scan through the file (without consulting CD). + while dd_offset + 8 < #data do -- Size field is at offset 4 (if sig exists) or at offset 8 otherwise. local size_offset - if tvb(dd_offset, 4):le_uint() == 0x08074b50 then + if Struct.unpack("<I4", data, dd_offset + 1) == 0x08074b50 then + -- Expecting Data descriptor past the signature (of length 16) + if dd_offset + 16 > #data then return end size_offset = dd_offset + 8 - -- If overflowing, size must be invalid. - if size_offset + 4 > length then return end else size_offset = dd_offset + 4 end -- Validata size or continue with next byte on failure. - local comp_size = tvb(size_offset, 4):le_uint() + local comp_size = Struct.unpack("<I4", data, size_offset + 1) if comp_size == dd_offset then return dd_offset, (size_offset - dd_offset) + 8 else |