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Add Alternative Packet Block
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This modification is based on the proposal submitted to the pcap-ng-formati
mailing list. It introduces two new features:

- Alternative Packet Block
- Simple Option Type
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@saleyn
saleyn committed Aug 16, 2016
1 parent 547a1d4 commit 5c71ad5
Showing 1 changed file with 151 additions and 3 deletions.
154 changes: 151 additions & 3 deletions draft-tuexen-opsawg-pcapng.xml
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Expand Up @@ -632,6 +632,40 @@ Section Header

</section>

<section anchor="section_simple_option" title="Simple Options">

<t>Simple Options are used for represending integer values that fit
into 24 bits of space.

<figure anchor="formatsimpleopt" title="Simple Options Format">
<artwork xml:space="preserve" name="" type="" align="center" alt="" width="" height="">
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Option Code | Option Value |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
</artwork>
</figure>
</t>
<t>A Simple Option has the following fields:
<list style="symbols">

<t>Simple Option Code: The code number for the Simple Option, which
has the upper three bits set to '001'. Given the total size of the
option code equal to 8 bits, there are at most 32 distinct simple
option codes available for each block type.
</t>

<t>Option Value: An integer value stored in 24bits.</t>
</list>

</t>

<t>See <xref target="section_apb"/> for examples of Simple Options
usage.</t>

</section>

</section>

<section title="Data format">
Expand Down Expand Up @@ -1903,11 +1937,125 @@ Section Header

<section title="Experimental Blocks (deserve further investigation)">

<section title="Alternative Packet Blocks (experimental)">
<section anchor="section_apb" title="Alternative Packet Blocks (experimental)">

<t>Alternative Packet Block offers an intermediate layout between
the Simple Packet Block and the Enhanced Packet Block. Just like the
Enhanced Packet Block it stores a timestamp of each packet, but
all other fields in the fixed part of the Alternative Packet
Block's body are made optional and can be stored in the Options
section. The packet's body of this block MAY be compressed.
</t>

<figure anchor="formatapb" title="Alternative Packet Block Format">
<artwork xml:space="preserve" name="" type="" align="left" alt="" width="" height="">
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+---------------------------------------------------------------+
0 | Block Type = 0x00000010 |
+---------------------------------------------------------------+
4 | Block Total Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
8 | Timestamp (High) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
12 | Timestamp (Low) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
16 / /
/ Options (variable) /
/ /
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ /
/ Packet Data /
/ variable length, padded to 32 bits /
/ /
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Block Total Length |
+---------------------------------------------------------------+
</artwork>
</figure>

<t>The permissible options listed in the table below are of
Simple Option type (see <xref target="section_simple_option"/>)
</t>

<t>Can some other packet blocks (besides the ones described in the
previous paragraphs) be useful?</t>
<texttable anchor="options_apb" title="Alternative Packet Block Options">
<ttcol align="left">Name</ttcol>
<ttcol align="left">Code</ttcol>
<ttcol align="left">Length</ttcol>
<ttcol align="left">Multiple allowed?</ttcol>

<c>apb_opt_size</c>
<c>0x2001</c>
<c>-</c>
<c>no</c>

<c>apb_orig_len</c>
<c>0x2002</c>
<c>-</c>
<c>no</c>

<c>apb_iface_id</c>
<c>0x2003</c>
<c>-</c>
<c>no</c>

<c>apb_flags</c>
<c>0x2004</c>
<c>-</c>
<c>no</c>
</texttable>

<t>
<list hangIndent="8" style="hanging">
<t hangText="apb_opt_size:"><vspace blankLines="0"/>
Total byte size of options. If this option is specified, then
the opt_endofopt option is OPTIONAL. The value of apb_opt_size
is the number of octets comprising the entire Options section in
this block. If present, this option MUST be the first one in the
Options data.</t>

<t hangText="apb_orig_len:"><vspace blankLines="0"/>Packet's
Original Length. Actual length of the packet when it was
transmitted on the network. It can be different from captured
packet length, which is the min(snapshot length, bytes left in
the block), if the packet has been truncated by the capture
process.</t>

<t hangText="apb_iface_id:"><vspace blankLines="0"/>It
specifies the interface this packet comes from; the correct
interface will be the one whose Interface Description Block
(within the current Section of the file) is identified by
the same value (see <xref target="section_idb"/>) of this
option. The interface ID MUST be valid, which means that an
matching interface description block MUST exist.</t>

<t hangText="apb_flags:"><vspace blankLines="0"/>Flags that
indicate characteristics of the Packet Data. See
<xref target="apb_flags"/> for permissible bit settings.</t>
</list>
</t>

<texttable title="Alternative Packet Block Flags" anchor="apb_flags">
<ttcol align="left">Bit Number</ttcol>
<ttcol align="left">Description</ttcol>

<c>0-1</c>
<c>Inbound / Outbound packet (00 = information not
available, 01 = inbound, 10 = outbound)</c>

<c>2-4</c>
<c>Reception type (000 = not specified, 001 = unicast,
010 = multicast, 011 = broadcast, 100 = promiscuous).</c>

<c>5-12</c>
<c>Compression type. When specified, the Packet Data
content is compressed. Permissible types:
0 (uncompressed), 1 (lzw), 2 (gzip), 3 (bzip2), 4 (zip),
5 (7z), 6 (lzo), 7 (ucl), 8 (snappy), other???</c>

<c>13-23</c>
<c>Reserved</c>
</texttable>
</section>

<section title="Compression Block (experimental)">
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