isodump(5) Linux IEEE 1394 isodump(5)NAME
isodump - format of IEEE 1394 isochronous packets dump file
DESCRIPTION
The isodump format stores a series of IEEE 1394 isochronous stream packets (possibly from multiple channels), including their headers. Its
main use is as the output format of dumpiso(1) and the input format of sendiso(1).
The 32 byte header starts at offset 0 with the string "1394 isodump v1" followed by a zero byte. The next 8 bytes form a 64 bit big endian
integer, which represents a bit mask of the channels that were dumped. A set bit at position (1 << x) signifies that channel x was being
listened on. The following 8 bytes are set to zero.
The iso packets follow the header and are appended to the data stream in the order they were received. The packets consist of the header
quadlet as originally received and the data quadlets following directly. The CRC quadlets after header and data do not appear and every-
thing is in big endian, as seen on the bus.
There is no further framing of the packets in the format, packet boundaries can be found by looking at the data size field in the header
quadlet of each packet. The data size field appears in the most significant 16 bits of the header quadlet, contain the size in bytes (the
actual packet is padded to a multiple of four bytes) and do not include the header packet.
COMPATIBILITY
This format was introduced with the iso send and dump tools distributed with libraw1394. No one else uses it so far.
SEE ALSO sendiso(1), dumpiso(1)AUTHOR
Andreas Bombe <aeb@debian.org>
libraw1394 2.0.9 isodump v1 isodump(5)
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PCAP-SAVEFILE(5@) PCAP-SAVEFILE(5@)
NAME
pcap-savefile - libpcap savefile format
DESCRIPTION
NOTE: applications and libraries should, if possible, use libpcap to read savefiles, rather than having their own code to read savefiles.
If, in the future, a new file format is supported by libpcap, applications and libraries using libpcap to read savefiles will be able to
read the new format of savefiles, but applications and libraries using their own code to read savefiles will have to be changed to support
the new file format.
``Savefiles'' read and written by libpcap and applications using libpcap start with a per-file header. The format of the per-file header
is:
+------------------------------+
| Magic number |
+--------------+---------------+
|Major version | Minor version |
+--------------+---------------+
| Time zone offset |
+------------------------------+
| Time stamp accuracy |
+------------------------------+
| Snapshot length |
+------------------------------+
| Link-layer header type |
+------------------------------+
All fields in the per-file header are in the byte order of the host writing the file. The first field in the per-file header is a 4-byte
magic number, with the value 0xa1b2c3d4. The magic number, when read by a host with the same byte order as the host that wrote the file,
will have the value 0xa1b2c3d4, and, when read by a host with the opposite byte order as the host that wrote the file, will have the value
0xd4c3b2a1. That allows software reading the file to determine whether the byte order of the host that wrote the file is the same as the
byte order of the host on which the file is being read, and thus whether the values in the per-file and per-packet headers need to be byte-
swapped.
Following this are:
A 2-byte file format major version number; the current version number is 2.
A 2-byte file format minor version number; the current version number is 4.
A 4-byte time zone offset; this is always 0.
A 4-byte number giving the accuracy of time stamps in the file; this is always 0.
A 4-byte number giving the "snapshot length" of the capture; packets longer than the snapshot length are truncated to the snapshot
length, so that, if the snapshot length is N, only the first N bytes of a packet longer than N bytes will be saved in the capture.
a 4-byte number giving the link-layer header type for packets in the capture; see pcap-linktype(7) for the LINKTYPE_ values that can
appear in this field.
Following the per-file header are zero or more packets; each packet begins with a per-packet header, which is immediately followed by the
raw packet data. The format of the per-packet header is:
+---------------------------------------+
| Time stamp, seconds value |
+---------------------------------------+
| Time stamp, microseconds value |
+---------------------------------------+
| Length of captured packet data |
+---------------------------------------+
|Un-truncated length of the packet data |
+---------------------------------------+
All fields in the per-packet header are in the byte order of the host writing the file. The per-packet header begins with a time stamp
giving the approximate time the packet was captured; the time stamp consists of a 4-byte value, giving the time in seconds since January 1,
1970, 00:00:00 UTC, followed by a 4-byte value, giving the time in microseconds since that second. Following that are a 4-byte value giv-
ing the number of bytes of captured data that follow the per-packet header and a 4-byte value giving the number of bytes that would have
been present had the packet not been truncated by the snapshot length. The two lengths will be equal if the number of bytes of packet data
are less than or equal to the snapshot length.
SEE ALSO pcap(3PCAP), pcap-linktype(7)
21 October 2008 PCAP-SAVEFILE(5@)