forked from osmocom/wireshark
bf26f538c6
Libpcap assumes that packet length is greater or equal to captured data length. However, due to a bug in libpcap, it was possible for libpcap to generate isochronous URB packets (WTAP_ENCAP_USB_LINUX_MMAPPED) with captured data length greater than packet length. The discrepancy comes from slightly different semantics in Linux kernel. Linux kernel usbmon packet documentation mentions: unsigned int length; /* 32: Length of data (submitted or actual) */ unsigned int len_cap; /* 36: Delivered length */ Wireshark shows usbmon packet length as URB length (usb.urb_len) and len_cap as Data length (usb.data_len). For usbmon isochronous IN packets containing data (URB complete), usbmon length is "actual". Actual length is the sum of payload packets length received from device. Delivered length refers to the amount of data associated with usbmon packet, that is the isochronous descriptors and actual isochronous data. There can be multiple isochronous descriptors in single URB and the actual payload in special cases can be noncontiguous (there can be gaps). Libpcap when reading usbmon capture calculates packet length based on usbmon packet structure size (64), "actual length" and number of isochronous descriptors. This gives expected packet length as long as there are no gaps between isochronous data. If there are gaps, the calculated packet length will be smaller than delivered length. Wireshark should show the frame length and captured length as provided by the capture engine, even if the capture length is greater than frame length. Silently limiting captured length essentially hides the issue from the user and allows misbehaving capture engine to go unnoticed. Passing unmodified Frame Length and Capture Length to dissectors (and thus complete tvb) allows USB dissector to show all ISO Data fields captured on Linux usbmon interface using bugged libpcap. Fixes #18021 |
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.. | ||
.editorconfig | ||
5views.c | ||
5views.h | ||
CMakeLists.txt | ||
README | ||
README.airmagnet | ||
README.developer | ||
aethra.c | ||
aethra.h | ||
ascend-int.h | ||
ascend_parser.lemon | ||
ascend_scanner.l | ||
ascendtext.c | ||
ascendtext.h | ||
atm.c | ||
atm.h | ||
ber.c | ||
ber.h | ||
blf.c | ||
blf.h | ||
btsnoop.c | ||
btsnoop.h | ||
busmaster.c | ||
busmaster.h | ||
busmaster_parser.lemon | ||
busmaster_priv.h | ||
busmaster_scanner.l | ||
camins.c | ||
camins.h | ||
candump.c | ||
candump.h | ||
candump_parser.lemon | ||
candump_priv.h | ||
candump_scanner.l | ||
capsa.c | ||
capsa.h | ||
catapult_dct2000.c | ||
catapult_dct2000.h | ||
commview.c | ||
commview.h | ||
cosine.c | ||
cosine.h | ||
csids.c | ||
csids.h | ||
daintree-sna.c | ||
daintree-sna.h | ||
dbs-etherwatch.c | ||
dbs-etherwatch.h | ||
dct3trace.c | ||
dct3trace.h | ||
dpa400.c | ||
dpa400.h | ||
erf-common.h | ||
erf.c | ||
erf.h | ||
erf_record.h | ||
eri_enb_log.c | ||
eri_enb_log.h | ||
eyesdn.c | ||
eyesdn.h | ||
file_access.c | ||
file_wrappers.c | ||
file_wrappers.h | ||
hcidump.c | ||
hcidump.h | ||
i4b_trace.h | ||
i4btrace.c | ||
i4btrace.h | ||
ipfix.c | ||
ipfix.h | ||
iptrace.c | ||
iptrace.h | ||
iseries.c | ||
iseries.h | ||
json.c | ||
json.h | ||
k12.c | ||
k12.h | ||
k12text.l | ||
lanalyzer.c | ||
lanalyzer.h | ||
libpcap.c | ||
libpcap.h | ||
log3gpp.c | ||
log3gpp.h | ||
logcat.c | ||
logcat.h | ||
logcat_text.c | ||
logcat_text.h | ||
merge.c | ||
merge.h | ||
mime_file.c | ||
mime_file.h | ||
mp2t.c | ||
mp2t.h | ||
mp4.c | ||
mp4.h | ||
mpeg.c | ||
mpeg.h | ||
mplog.c | ||
mplog.h | ||
netmon.c | ||
netmon.h | ||
netscaler.c | ||
netscaler.h | ||
netscreen.c | ||
netscreen.h | ||
nettl.c | ||
nettl.h | ||
nettrace_3gpp_32_423.c | ||
nettrace_3gpp_32_423.h | ||
netxray.c | ||
netxray.h | ||
ngsniffer.c | ||
ngsniffer.h | ||
observer.c | ||
observer.h | ||
packetlogger.c | ||
packetlogger.h | ||
pcap-common.c | ||
pcap-common.h | ||
pcap-encap.h | ||
pcapng.c | ||
pcapng.h | ||
pcapng_module.h | ||
peekclassic.c | ||
peekclassic.h | ||
peektagged.c | ||
peektagged.h | ||
pppdump.c | ||
pppdump.h | ||
radcom.c | ||
radcom.h | ||
required_file_handlers.h | ||
rfc7468.c | ||
rfc7468.h | ||
ruby_marshal.c | ||
ruby_marshal.h | ||
secrets-types.h | ||
snoop.c | ||
snoop.h | ||
socketcan.h | ||
stanag4607.c | ||
stanag4607.h | ||
systemd_journal.c | ||
systemd_journal.h | ||
tnef.c | ||
tnef.h | ||
toshiba.c | ||
toshiba.h | ||
visual.c | ||
visual.h | ||
vms.c | ||
vms.h | ||
vwr.c | ||
vwr.h | ||
wtap-int.h | ||
wtap.c | ||
wtap.h | ||
wtap_modules.h | ||
wtap_opttypes.c | ||
wtap_opttypes.h |
README
NOTE: this documents the original intent behind libwiretap. Currently, it is being developed solely as a library for reading capture files, rather than packet capture. The list of file formats is also out-of-date. Wiretap is a library that is being developed as a future replacement for libpcap, the current standard Unix library for packet capturing. Libpcap is great in that it is very platform independent and has a wonderful BPF optimizing engine. But it has some shortcomings as well. These shortcomings came to a head during the development of Wireshark (https://www.wireshark.org/), a packet analyzer. As such, I began developing wiretap so that: 1. The library can easily be amended with new packet filtering objects. Libpcap is very TCP/IP-oriented. I want to filter on IPX objects, SNA objects, etc. I also want any decent programmer to be able to add new filters to the library. 2. The library can read file formats from many packet-capturing utilities. Libpcap only reads Libpcap files. 3. The library can capture on more than one network interface at a time, and save this trace in one file. 4. Network names can be resolved immediately after a trace and saved in the trace file. That way, I can ship a trace of my firewall-protected network to a colleague, and he'll see the proper hostnames for the IP addresses in the packet capture, even though he doesn't have access to the DNS server behind my LAN's firewall. 5. I want to look into the possibility of compressing packet data when saved to a file, like Sniffer. 6. The packet-filter can be optimized for the host OS. Not all OSes have BPF; SunOS has NIT and Solaris has DLPI, which both use the CMU/Stanford packet-filter pseudomachine. RMON has another type of packet-filter syntax which we could support. Wiretap is very good at reading many file formats, as per #2 above. Wiretap has no filter capability at present; it currently doesn't support packet capture, so it wouldn't be useful there, and filtering when reading a capture file is done by Wireshark, using a more powerful filtering mechanism than that provided by BPF. File Formats ============ Libpcap ------- The "libpcap" file format was determined by reading the "libpcap" code; wiretap reads the "libpcap" file format with its own code, rather than using the "libpcap" library's code to read it. Sniffer (compressed and uncompressed) ------- The uncompressed Sniffer format is documented in the Sniffer manual. Unfortunately, Sniffer manuals tend to document only the format for the Sniffer model they document. Token-Ring and ethernet seems to work well, though. If you have an ATM Sniffer file, both Guy and Gilbert would be *very* interested in receiving a sample. (see 'AUTHORS' file for our e-mail addresses). LANalyzer --------- The LANalyzer format is available from http://www.novell.com. Search their knowledge base for "Trace File Format". Network Monitor --------------- Microsoft's Network Monitor file format is supported, at least under Ethernet and token-ring. If you have capture files of other datalink types, please send them to Guy. "snoop" ------- The Solaris 2.x "snoop" program's format is documented in RFC 1761. "iptrace" --------- This is the capture program that comes with AIX 3.x and 4.x. AIX 3 uses the iptrace 1.0 file format, while AIX4 uses iptrace 2.0. iptrace has an undocumented, yet very simple, file format. The interesting thing about iptrace is that it will record packets coming in from all network interfaces; a single iptrace file can contain multiple datalink types. Sniffer Basic (NetXRay)/Windows Sniffer Pro ------------------------------------------- Network Associates' Sniffer Basic (formerly NetXRay from Cinco Networks) file format is now supported, at least for Ethernet and token-ring. Network Associates' Windows Sniffer Pro appears to use a variant of that format; it's supported to the same extent. RADCOM WAN/LAN Analyzers ------------------------ Olivier Abad has added code to read Ethernet and LAPB captures from RADCOM WAN/LAN Analyzers (see https://web.archive.org/web/20031231213434/http://www.radcom-inc.com/). Lucent/Ascend access products ----------------------------- Gerald HP-UX nettl ----------- nettl is used on HP-UX to trace various streams based subsystems. Wiretap can read nettl files containing IP frames (NS_LS_IP subsystem) and LAPB frames (SX25L2 subsystem). It has been tested with files generated on HP-UX 9.04 and 10.20. Use the following commands to generate a trace : # IP capture. 0x30000000 means PDU in and PDU out : nettl -tn 0x30000000 -e NS_LS_IP -f tracefile # X25 capture. You must specify an interface : nettl -tn 0x30000000 -e SX25l2 -d /dev/x25_0 -f tracefile # stop capture. subsystem is NS_LS_IP or SX25L2 : nettl -tf -e subsystem One may be able to specify "-tn pduin pduout" rather than "-tn 0x30000000"; the nettl man page for HP-UX 10.30 implies that it should work. There is also basic support for nettl files containing NS_LS_DRIVER, NS_LS_TCP, NS_LS_UDP, NS_LS_LOOPBACK, unknown type 0xb9, and NS_LS_ICMP. However, NS_LS_ICMP will not be decoded since WTAP lacks a raw ICMP encapsulation type. Toshiba ISDN Router ------------------- An under-documented command that the router supports in a telnet session is "snoop" (not related to the Solaris "snoop" command). If you give it the "dump" option (either by letting "snoop" query you for its next argument, or typing "snoop dump" on the command line), you'll get a hex dump of all packets across the router (except of your own telnet session -- good thinking Toshiba!). You can select a certain channel to sniff (LAN, B1, B2, D), but the default is all channels. You save this hex dump to disk with 'script' or by 'telnet | tee'. Wiretap will read the ASCII hex dump and convert it to binary data. ISDN4BSD "i4btrace" utility --------------------------- Bert Driehuis Cisco Secure Intrusion Detection System iplogging facility ----------------------------------------------------------- Mike Hall pppd logs (pppdump-format files) -------------------------------- Gilbert VMS TCPTRACE ------------ Compaq VMS's TCPIPTRACE format is supported. This is the capture program that comes with TCP/IP or UCX as supplied by Compaq or Digital Equipment Corporation. Under UCX 4.x, it is invoked as TCPIPTRACE. Under TCPIP 5.x, it is invoked as TCPTRACE. TCPTRACE produces an ascii text based format, that has changed slightly over time. DBS Etherwatch (text format) ---------------------------- Text output from DBS Etherwatch is supported. DBS Etherwatch is available from: https://web.archive.org/web/20070612033348/http://www.users.bigpond.com/dbsneddon/software.htm. Catapult DCT2000 (.out files) ----------------------------- DCT2000 test systems produce ascii text-based .out files for ports that have logging enabled. When being read, the data part of the message is prefixed with a short header that provides some context (context+port, direction, original timestamp, etc). You can choose to suppress the reading of non-standard protocols (i.e. messages between layers rather than the well-known link-level protocols usually found on board ports). Gilbert Ramirez <gram@alumni.rice.edu> Guy Harris <guy@alum.mit.edu> STANAG 4607 ----------- Initial support for the STANAG 4607 protocol. Documentation at: https://web.archive.org/web/20130223054955/http://www.nato.int/structur/AC/224/standard/4607/4607.htm