1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
|
--
-- Zip Archive dissector
-- Author: Peter Wu <peter@lekensteyn.nl>
--
-- Spec: https://en.wikipedia.org/wiki/Zip_(file_format)#File_headers
--
--
-- Dissection of Zip file contents
--
-- takes a table where keys are the field names and values are descriptions of
-- fields. If a value is a table without numeric indicdes, assume that it is a
-- nested tree.
local function make_fields(field_abbr_prefix, field_defs, hfs_out, hfs_list_out)
for name, params in pairs(field_defs) do
if #params == 0 then
-- Assume nested table, flatten it
hfs_out[name] = {}
make_fields(field_abbr_prefix .. name .. ".", params,
hfs_out[name], hfs_list_out)
else
local proto_field_constructor = params[1]
local field_abbr = field_abbr_prefix .. name
local field
if type(params[2]) == "string" then
-- Name was given, use it
field = proto_field_constructor(field_abbr, unpack(params, 2))
else
-- Name was not given, use field name (the suffix)
field = proto_field_constructor(field_abbr, name, unpack(params, 2))
end
hfs_out[name] = field
table.insert(hfs_list_out, field)
end
end
end
local proto_zip = Proto.new("zip_archive", "Zip Archive")
local hf = {}
local general_purpose_flags_def = {
_ = {ProtoField.uint16, "General purpose bit flag", base.HEX},
-- TODO fix wslua documentation, it is wrong on ProtoField.bool.
encrypted = {ProtoField.bool, "Is encrypted", 16, nil, 0x0001},
comp_option = {ProtoField.bool, "Compr-specific options", 16, nil, 0x0006},
has_data_desc = {ProtoField.bool, "Data descriptor present", 16, nil, 0x0008},
enhanced_deflate= {ProtoField.bool, "Enhanced deflating", 16, nil, 0x0010},
compr_patched = {ProtoField.bool, "Compressed patched data", 16, nil, 0x0020},
strong_encrypt = {ProtoField.bool, "Strong encryption", 16, nil, 0x0040},
unused = {ProtoField.bool, "Unused", 16, nil, 0x0780},
lang_encoding = {ProtoField.bool, "Language encoding", 16, {"UTF-8", "System-specific"}, 0x0800},
enhanced_compr = {ProtoField.bool, "Enhanced compression", 16, nil, 0x1000},
hdr_data_masked = {ProtoField.bool, "Local Header data masked", 16, nil, 0x2000},
reserved = {ProtoField.bool, "Reserved", 16, nil, 0xc000},
}
local extra_def = {
_ = {ProtoField.none, "Extensible data fields"},
header_id = {ProtoField.uint16, base.HEX, {
[0xcafe] = "Jar magic number", -- see java/util/jar/JarOutputStream.java
}},
data_size = {ProtoField.uint16, base.DEC},
}
make_fields("zip_archive", {
signature = {ProtoField.uint32, base.HEX},
entry = {
_ = {ProtoField.none, "File entry"},
version = {ProtoField.uint16, base.DEC},
flag = general_purpose_flags_def,
comp_method = {ProtoField.uint16, base.HEX},
lastmod_time = {ProtoField.uint16, base.HEX},
lastmod_date = {ProtoField.uint16, base.HEX},
crc32 = {ProtoField.uint32, base.HEX},
size_comp = {ProtoField.uint32, base.DEC},
size_uncomp = {ProtoField.uint32, base.DEC},
filename_len = {ProtoField.uint16, base.DEC},
extra_len = {ProtoField.uint16, base.DEC},
filename = {ProtoField.string},
extra = extra_def,
data = {ProtoField.bytes},
data_desc = {
_ = {ProtoField.none, "Data descriptor"},
crc32 = {ProtoField.uint32, base.HEX},
size_comp = {ProtoField.uint32, base.DEC},
size_uncomp = {ProtoField.uint32, base.DEC},
},
},
cd = {
_ = {ProtoField.none, "Central Directory Record"},
version_made = {ProtoField.uint16, base.HEX_DEC},
version_extract = {ProtoField.uint16, base.HEX_DEC},
flag = general_purpose_flags_def,
comp_method = {ProtoField.uint16, base.HEX},
lastmod_time = {ProtoField.uint16, base.HEX},
lastmod_date = {ProtoField.uint16, base.HEX},
crc32 = {ProtoField.uint32, base.HEX},
size_comp = {ProtoField.uint32, base.DEC},
size_uncomp = {ProtoField.uint32, base.DEC},
filename_len = {ProtoField.uint16, base.DEC},
extra_len = {ProtoField.uint16, base.DEC},
comment_len = {ProtoField.uint16, base.DEC},
disk_number = {ProtoField.uint16, base.DEC},
attr_intern = {ProtoField.uint16, base.HEX},
attr_extern = {ProtoField.uint32, base.HEX},
relative_offset = {ProtoField.uint32, base.HEX_DEC},
filename = {ProtoField.string},
extra = extra_def,
comment = {ProtoField.string},
},
eocd = {
_ = {ProtoField.none, "End of Central Directory Record"},
disk_number = {ProtoField.uint16, base.DEC},
disk_start = {ProtoField.uint16, base.DEC},
num_entries = {ProtoField.uint16, base.DEC},
num_entries_total = {ProtoField.uint16, base.DEC},
size = {ProtoField.uint32, base.DEC},
relative_offset = {ProtoField.uint32, base.HEX_DEC},
comment_len = {ProtoField.uint16, base.DEC},
},
}, hf, proto_zip.fields)
--[[ This can be used when implementing a "proper" program.
--
-- Parse Zip Archive as follows:
-- 1. Find EOCD, obtain CD offset and length
-- 2. Find first CD. Then for each CD:
-- 2a. Obtain Local File Header offset and data size.
-- 2b. Find Local File Header.
-- ...
--
local function find_eocd(tvb)
if tvb(0, 4):le_uint() ~= 0x06054b50 then
-- Magic not found... possibly comment present
return
end
return {
offset = tvb(16, 4):le_uint(),
length = tvb(12, 4):le_uint(),
}
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()
-- 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
-- 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
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()
if comp_size == dd_offset then
return dd_offset, (size_offset - dd_offset) + 8
else
dd_offset = dd_offset + 1
end
end
end
local function dissect_flags(hfs, tvb, tree)
local flgtree = tree:add_le(hfs._, tvb)
-- TODO why does flag.has_data_desc segfault if tvb is not given?
flgtree:add_le(hfs.encrypted, tvb)
flgtree:add_le(hfs.comp_option, tvb)
flgtree:add_le(hfs.has_data_desc, tvb)
flgtree:add_le(hfs.enhanced_deflate,tvb)
flgtree:add_le(hfs.compr_patched, tvb)
flgtree:add_le(hfs.strong_encrypt, tvb)
flgtree:add_le(hfs.unused, tvb)
flgtree:add_le(hfs.lang_encoding, tvb)
flgtree:add_le(hfs.enhanced_compr, tvb)
flgtree:add_le(hfs.hdr_data_masked, tvb)
flgtree:add_le(hfs.reserved, tvb)
end
local function dissect_extra(hfs, tvb, tree)
local etree = tree:add(hfs._, tvb)
local offset, length = 0, tvb:len()
while offset + 4 <= length do
etree:add_le(hfs.header_id, tvb(offset, 2))
etree:add_le(hfs.data_size, tvb(offset + 2, 2))
local data_size = tvb(offset + 2, 2):le_uint()
offset = offset + 4 + data_size
end
end
local function dissect_one(tvb, offset, pinfo, tree)
local orig_offset = offset
local magic = tvb(offset, 4):le_int()
if magic == 0x04034b50 then -- File entry
local subtree = tree:add_le(hf.entry._, tvb(offset, 30))
-- header
subtree:add_le(hf.signature, tvb(offset, 4))
subtree:add_le(hf.entry.version, tvb(offset + 4, 2))
dissect_flags(hf.entry.flag, tvb(offset + 6, 2), subtree)
subtree:add_le(hf.entry.comp_method, tvb(offset + 8, 2))
subtree:add_le(hf.entry.lastmod_time, tvb(offset + 10, 2))
subtree:add_le(hf.entry.lastmod_date, tvb(offset + 12, 2))
subtree:add_le(hf.entry.crc32, tvb(offset + 14, 4))
subtree:add_le(hf.entry.size_comp, tvb(offset + 18, 4))
subtree:add_le(hf.entry.size_uncomp, tvb(offset + 22, 4))
subtree:add_le(hf.entry.filename_len, tvb(offset + 26, 2))
subtree:add_le(hf.entry.extra_len, tvb(offset + 28, 2))
local flag = tvb(offset + 6, 2):le_uint()
local data_len = tvb(offset + 18, 2):le_uint()
local filename_len = tvb(offset + 26, 2):le_uint()
local extra_len = tvb(offset + 28, 2):le_uint()
-- Optional data descriptor follows data if GP flag bit 3 (0x8) is set
local ddlen
if bit.band(flag, 8) ~= 0 then
local data_offset = offset + 30 + filename_len + extra_len
data_len, ddlen = find_data_desc(tvb(data_offset))
end
-- skip header
offset = offset + 30
subtree:add(hf.entry.filename, tvb(offset, filename_len))
subtree:append_text(": " .. tvb(offset, filename_len):string())
offset = offset + filename_len
if extra_len > 0 then
dissect_extra(hf.entry.extra, tvb(offset, extra_len), subtree)
offset = offset + extra_len
end
if data_len and data_len > 0 then
subtree:add(hf.entry.data, tvb(offset, data_len))
offset = offset + data_len
end
-- Optional data descriptor header
if ddlen then
local dd_offset = offset
local ddtree = subtree:add_le(hf.entry.data_desc._, tvb(dd_offset, ddlen))
if ddlen == 16 then
ddtree:add_le(hf.signature, tvb(dd_offset, 4))
dd_offset = dd_offset + 4
end
ddtree:add_le(hf.entry.data_desc.crc32, tvb(dd_offset, 4))
ddtree:add_le(hf.entry.data_desc.size_comp, tvb(dd_offset + 4, 4))
ddtree:add_le(hf.entry.data_desc.size_uncomp, tvb(dd_offset + 8, 4))
offset = offset + ddlen
end
subtree:set_len(offset - orig_offset)
return offset
elseif magic == 0x02014b50 then -- Central Directory
local subtree = tree:add_le(hf.cd._, tvb(offset, 46))
subtree:add_le(hf.signature, tvb(offset, 2))
subtree:add_le(hf.cd.version_made, tvb(offset + 4, 2))
subtree:add_le(hf.cd.version_extract, tvb(offset + 6, 2))
dissect_flags(hf.cd.flag, tvb(offset + 8, 2), subtree)
subtree:add_le(hf.cd.comp_method, tvb(offset + 10, 2))
subtree:add_le(hf.cd.lastmod_time, tvb(offset + 12, 2))
subtree:add_le(hf.cd.lastmod_date, tvb(offset + 14, 2))
subtree:add_le(hf.cd.crc32, tvb(offset + 16, 4))
subtree:add_le(hf.cd.size_comp, tvb(offset + 20, 4))
subtree:add_le(hf.cd.size_uncomp, tvb(offset + 24, 4))
subtree:add_le(hf.cd.filename_len, tvb(offset + 28, 2))
subtree:add_le(hf.cd.extra_len, tvb(offset + 30, 2))
subtree:add_le(hf.cd.comment_len, tvb(offset + 32, 2))
subtree:add_le(hf.cd.disk_number, tvb(offset + 34, 2))
subtree:add_le(hf.cd.attr_intern, tvb(offset + 36, 2))
subtree:add_le(hf.cd.attr_extern, tvb(offset + 38, 4))
subtree:add_le(hf.cd.relative_offset, tvb(offset + 42, 4))
local filename_len = tvb(offset + 28, 2):le_uint()
local extra_len = tvb(offset + 30, 2):le_uint()
local comment_len = tvb(offset + 32, 2):le_uint()
-- skip header
offset = offset + 46
subtree:add(hf.cd.filename, tvb(offset, filename_len))
subtree:append_text(": " .. tvb(offset, filename_len):string())
offset = offset + filename_len
if extra_len > 0 then
dissect_extra(hf.cd.extra, tvb(offset, extra_len), subtree)
offset = offset + extra_len
end
if comment_len > 0 then
subtree:add(hf.cd.comment, tvb(offset, comment_len))
offset = offset + comment_len
end
subtree:set_len(offset - orig_offset)
return offset
elseif magic == 0x06054b50 then -- End of Central Directory
local subtree = tree:add_le(hf.cd._, tvb(offset, 22))
subtree:add_le(hf.signature, tvb(offset, 4))
subtree:add_le(hf.eocd.disk_number, tvb(offset + 4, 2))
subtree:add_le(hf.eocd.disk_start, tvb(offset + 6, 2))
subtree:add_le(hf.eocd.num_entries, tvb(offset + 8, 2))
subtree:add_le(hf.eocd.num_entries_total, tvb(offset + 10, 2))
subtree:add_le(hf.eocd.size, tvb(offset + 12, 4))
subtree:add_le(hf.eocd.relative_offset, tvb(offset + 16, 4))
subtree:add_le(hf.eocd.comment_len, tvb(offset + 20, 2))
local comment_len = tvb(offset + 20, 2):le_uint()
offset = offset + 22
if comment_len > 0 then
subtree:add(hf.eocd.comment, tvb(offset, comment_len))
offset = offset + comment_len
end
subtree:set_len(offset - orig_offset)
return offset
elseif tvb:raw(offset, 2) == "PK" then
-- Unknown signature
tree:add_le(hf.signature, tvb(offset, 4))
end
end
function proto_zip.dissector(tvb, pinfo, tree)
pinfo.cols.protocol = "zip"
--pinfo.cols.info = ""
local next_offset = 0
while next_offset and next_offset < tvb:len() do
next_offset = dissect_one(tvb, next_offset, pinfo, tree)
end
return next_offset
end
local function zip_heur(tvb, pinfo, tree)
if tvb:raw(0, 2) ~= "PK" then
return false
end
proto_zip.dissector(tvb, pinfo, tree)
return true
end
-- Register MIME types in case a Zip file appears over HTTP.
DissectorTable.get("media_type"):add("application/zip", proto_zip)
DissectorTable.get("media_type"):add("application/java-archive", proto_zip)
-- Ensure that files can directly be opened (after any FileHandler has accepted
-- it, see below).
proto_zip:register_heuristic("wtap_file", zip_heur)
--
-- File handler (for directly interpreting opening a Zip file in Wireshark)
-- Actually, all it does is recognizing a Zip file and passing one packet to the
-- MIME dissector.
--
local zip_fh = FileHandler.new("Zip", "zip", "Zip archive file reader", "rms")
-- Check if file is really a zip file (return true if it is)
function zip_fh.read_open(file, cinfo)
-- XXX improve heuristics?
if file:read(2) ~= "PK" then
return false
end
-- Find end of file and rewind.
local endpos, err = file:seek("end")
if not endpos then error("Error while finding end! " .. err) end
local ok, err = file:seek("set", 0)
if not ok then error("Non-seekable file! " .. err) end
cinfo.encap = wtap_encaps.MIME
cinfo.private_table = {
endpos = endpos,
}
return true
end
-- Read next packet (returns begin offset or false on error)
local function zip_fh_read(file, cinfo, finfo)
local p = cinfo.private_table
local curpos = file:seek("cur")
-- Fal on EOF
if curpos >= p.endpos then return false end
finfo.original_length = p.endpos - curpos
finfo.captured_length = p.endpos - curpos
if not finfo:read_data(file, finfo.captured_length) then
-- Partial read?
print("Hmm, partial read, curpos=" .. curpos .. ", len: " .. finfo.captured_length)
return false
end
return curpos
end
zip_fh.read = zip_fh_read
-- Reads packet at offset (returns true on success and false on failure)
function zip_fh.seek_read(file, cinfo, finfo, offset)
file:seek("set", offset)
-- Return a boolean since WS < 2.4 has an undocumented "feature" where
-- strings (including numbers) are treated as data.
return zip_fh_read(file, cinfo, finfo) ~= false
end
-- Hints for when to invoke this dissector.
zip_fh.extensions = "zip;jar"
register_filehandler(zip_fh)
|