A given protocol's packet format may depend, for example, on which
lower-level protocol is transporting the protocol in question. For
example, protocols that run atop both byte-stream protocols such as TCP
and TLS, and packet-oriented protocols such as UDP or DTLS, might begin
the packet with a length when running atop a byte-stream protocol, to
indicate where this packet ends and the next packet begins in the byte
stream, but not do so when running atop a packet-oriented protocol.
Dissectors can handle this in various ways:
For example, the dissector could attempt to determine the protocol over
which the packet was transported.
Unfortunately, many of those mechanisms do so by fetching data from the
packet_info structure, and many items in that structure act as global
variables, so that, for example, if there are two two PDUs for protocol
A inside a TCP segment, and the first protocol for PDU A contains a PDU
for protocol B, and protocol B's dissector, or a dissector it calls,
modifies the information in the packet_info structure so that it no
longer indicates that the parent protocol is TCP, the second PDU for
protocol A might not be correctly dissected.
Another such mechanism is to query the previous element in the layers
structure of the packet_info structure, which is a list of protocol IDs.
Unfortunately, that is not a list of earlier protocols in the protocol
stack, it's a list of earlier protocols in the dissection, which means
that, in the above example, when the second PDU for protocol A is
dissected, the list is {...,TCP,A,B,...,A}, which means that the
previous element in the list is not TCP, so, again, the second PDU for
protocol A will not be correctly dissected.
An alternative is to have multiple dissectors for the same protocol,
with the part of the protocol that's independent of the protocol
transporting the PDU being dissected by common code. Protocol B might
have an "over a byte-stream transport" dissector and an "over a packet
transport" dissector, with the first dissector being registered for use
over TCP and TLS and the other dissector being registered for use over
packet protocols. This mechanism, unlike the other mechanisms, is not
dependent on information in the packet_info structure that might be
affected by dissectors other than the one for the protocol that
transports protocol B.
Furthermore, in a LINKTYPE_WIRESHARK_UPPER_PDU pcap or pcapng packet for
protocol B, there might not be any information to indicate the protocol
that transports protocol B, so there would have to be separate
dissectors for protocol B, with separate names, so that a tag giving the
protocol name would differ for B-over-byte-stream and B-over-packets.
So:
We rename EXP_PDU_TAG_PROTO_NAME and EXP_PDU_TAG_HEUR_PROTO_NAME to
EXP_PDU_TAG_DISSECTOR_NAME and EXP_PDU_TAG_HEUR_DISSECTOR_NAME, to
emphasize that they are *not* protocol names, they are dissector names
(which has always been the case - if there's a protocol with that name,
but no dissector with that name, Wireshark will not be able to handle
the packet, as it will try to look up a dissector given that name and
fail).
We fix that exported PDU dissector to refer to those tags as dissector
names, not protocol names.
We update documentation to refer to them as DISSECTOR_NAME tags, not
PROTO_NAME tags. (If there is any documentation for this outside the
Wireshark source, it should be updated as well.)
We add comments for calls to dissector_handle_get_dissector_name() where
the dissector name is shown to the user, to indicate that it might be
that the protocol name should be used.
We update the TLS and DTLS dissectors to show the encapsulated protocol
as the string returned by dissector_handle_get_long_name(); as the
default is "Application Data", it appeaers that a descriptive name,
rather than a short API name, should be used. (We continue to use the
dissector name in debugging messages, to indicate which dissector was
called.)
For the upcoming 4.0 release, switch the default file format for
text2pcap to pcapng from pcap, to match other tools and the GUI
behavior. Update the documentation and release notes appropriately.
Deprecate the old -n flag; since pcapng is the default this has no
effect. Changing the output capture file format is supported with
the -F option, consistent with the other command line tools.
Related to #18009.
Update the text2pcap man page and the Import from Hexdump WSUG
page to clarify how to use it, for grammar, and to remove a few
things that are no longer relevant. (E.g., it's no longer the case that
files without an EOL don't work.)
Fix#15563, #15564.
Add an option to text2pcap to specify the encapsulation type
via wiretap encapsulation type short names instead of pcap
link layer types, similar to editcap.
Update the documentation to reflect this.
In text2pcap and Import from Hex Dump, allow fake IP headers with
the appropriate versions when the Raw IP, Raw IPv4, and Raw IPv6
encapsulations are specified. In such cases, do not add a dummy
Ethernet header.
Continue to reject other encapsulations besides these, Ethernet,
and Wireshark Upper PDU when appropriate. Add some checks for the
encapsulation type in text_import as well, instead of just assuming
that the callers handle it correctly.
Support all possible file formats that wiretap writes, using the
same "-F" flag that other CLI tools like editcap, mergecap, and tshark
support. Default is still pcap for now; a future commit will switch
to pcapng and remove the "-n" option, to match other CLI tools.
Add support in text2pcap for the regex mode added to "Import from
Hex Dump" in 3.6.0 The input and output indicators cannot (yet?)
be configured, and are set to the default of allowing any of "iI<"
for inbound and "oO>" for outbound. This reaches feature parity
between text2pcap and Import from Hex Dump, fixes#16724.
(There might be some more cleanups to do, including docs.)
Remove the '-d' option from text2pcap, and move the two levels
of debug messages in text2pcap and text_import to either
LOG_LEVEL_DEBUG or LOG_LEVEL_NOISY as appropriate.
Add docs/diagnostic-options.adoc, which is a snippet that documents our
various --log-* options. Include it in the dumpcap, rawshark, and tshark
man pages.
Make the ws_log_print_usage output more consistent.
Move our attributes.adoc includes to the very top of each man page.
Older versions of Asciidoctor complain if it's not at the top. and
additionally generate <file>.man instead of <file>.<section> if we don't
explictly supply an output file.
Add the program version to more commonly-used commands. We were labeling
output with "Output" and "Example output". Use "Example output"
everywhere. Other miscellaneous updates.
Convert doc/*.pod to Asciidoctor. This:
* Means we use the same markup for our man pages, the guides, and
release notes.
* Lets us add versions to our man pages.
* Gives us more formatting options, e.g. AsciiDoc supports `commands`,
nested lists and makes it easy to include version information. The
manpage backend doesn't seem to support tables very well,
unfortunately.
Convert our CMake configuration to produce *roff and html man pages
using Asciidoctor. Add a "manarg" block macro which makes our synopses
wrap correctly.
Similar to the release notes, guides, and FAQ, if Asciidoctor isn't
found the man pages won't be generated or installed.
Move Asciidoctor to the list of package build dependencies in various
places.
This commit includes the conversion script (pod2adoc.py), which will be
removed later.
Line count sanity check:
Man page .pod .adoc
androiddump 260 280
asn2deb 93 105
capinfos 401 471
captype 54 55
ciscodump 241 269
dftest 42 42
dpauxmon 153 169
dumpcap 464 534
editcap 528 583
etwdump 136 156
extcap 157 181
idl2deb 91 103
idl2wrs 120 100
mergecap 206 207
mmdbresolve 75 75
randpkt 107 111
randpktdump 158 184
rawshark 558 610
reordercap 76 78
sdjournal 145 157
sshdump 272 302
text2pcap 274 312
tshark 2135 2360
udpdump 133 151
wireshark-filter 486 479
wireshark 2967 3420
Guy Harris