NAME¶
ng_source —
netgraph node for traffic
generation
SYNOPSIS¶
#include <sys/types.h>
#include <netgraph/ng_source.h>
DESCRIPTION¶
The
source node acts as a source of packets according to the
parameters set up using control messages and input packets. The
ng_source node type is used primarily for testing and
benchmarking.
HOOKS¶
The
source node has two hooks:
input and
output. The
output hook must
remain connected, its disconnection will shutdown the node.
OPERATION¶
The operation of the node is as follows. Packets received on the
input hook are queued internally. When
output hook is connected,
ng_source
node assumes that its neighbour node is of
ng_ether(4) node
type. The neighbour is queried for its interface name. The
ng_source node then uses queue of the interface for its evil
purposes. The
ng_source node also disables
autosrc option on neighbour
ng_ether(4) node. If interface name cannot be obtained
automatically, it should be configured explicitly with the
NGM_SOURCE_SETIFACE
control message, and
autosrc should be turned off on
ng_ether(4) node manually.
Once interface is configured, upon receipt of a
NGM_SOURCE_START
control message the node starts
sending the previously queued packets out the
output
hook on every clock tick as fast as the connected interface will take them.
While active, on every clock tick the node checks the available space in the
interface queue and sends that many packets out its
output hook. Once the number of packets indicated in the
start message has been sent, or upon receipt of a
NGM_SOURCE_STOP
message, the node stops sending data.
CONTROL MESSAGES¶
This node type supports the generic control messages as well as the following,
which must be sent with the
NGM_SOURCE_COOKIE
attached.
NGM_SOURCE_GET_STATS
(getstats)
- Returns a structure containing the following fields:
- outOctets
- The number of octets/bytes sent out the
output hook.
- outFrames
- The number of frames/packets sent out the
output hook.
- queueOctets
- The number of octets queued from the
input hook.
- queueFrames
- The number of frames queued from the
input hook.
- startTime
- The time the last start message was received.
- endTime
- The time the last end message was received or the
output packet count was reached.
- elapsedTime
- Either endTime
-
startTime or current
time - startTime.
NGM_SOURCE_CLR_STATS
(clrstats)
- Clears and resets the statistics returned by
getstats (except queueOctets and
queueFrames).
NGM_SOURCE_GETCLR_STATS
(getclrstats)
- As getstats but clears the statistics at
the same time.
NGM_SOURCE_START
(start)
- This message requires a single
uint64_t parameter which is the number of packets to
send before stopping. Node starts sending the queued packets out the
output hook. The output hook
must be connected and node must have interface configured.
NGM_SOURCE_STOP
(stop)
- Stops the node if it is active.
NGM_SOURCE_CLR_DATA
(clrdata)
- Clears the packets queued from the
input hook.
NGM_SOURCE_SETIFACE
(setiface)
- This message requires the name of the interface to be
configured as an argument.
NGM_SOURCE_SETPPS
(setpps)
- This message requires a single
uint32_t parameter which puts upper limit on the
amount of packets sent per second.
NGM_SOURCE_SET_TIMESTAMP
(settimestamp)
- This message specifies that a timestamp (in the format of a
struct timeval) should be inserted in the
transmitted packets. This message requires a structure containing the
following fields:
- offset
- The offset from the beginning of the packet at which
the timestamp is to be inserted.
- flags
- Set to 1 to enable the timestamp.
NGM_SOURCE_GET_TIMESTAMP
(gettimestamp)
- Returns the current timestamp settings in the form of the
structure described above.
NGM_SOURCE_SET_COUNTER
(setcounter)
- This message specifies that a counter should be embedded in
transmitted packets. Up to four counters may be independently configured.
This message requires a structure containing the following fields:
- offset
- The offset from the beginning of the packet at which
the counter is to be inserted.
- flags
- Set to 1 to enable the counter.
- width
- The byte width of the counter. It may be 1, 2, or
4.
- next_val
- The value for the next insertion of the counter.
- min_val
- The minimum value to be used by the counter.
- max_val
- The maximum value to be used by the counter.
- increment
- The value to be added to the counter after each
insertion. It may be negative.
- index
- The counter to be configured, from 0 to 3.
NGM_SOURCE_GET_COUNTER
(getcounter)
- This message requires a single
uint8_t parameter which specifies the counter to
query. Returns the current counter settings in the form of the structure
described above.
SHUTDOWN¶
This node shuts down upon receipt of a
NGM_SHUTDOWN
control message, when all hooks have been disconnected, or when the
output hook has been disconnected.
EXAMPLES¶
Attach the node to an
ng_ether(4) node for an interface. If
ng_ether is not already loaded you will need to do so. For
example, these commands load the
ng_ether module and attach
the
output hook of a new
source node
to
orphans hook of the
bge0:
ng_ether node.
kldload ng_ether
ngctl mkpeer bge0: source orphans output
At this point the new node can be referred to as
“
bge0:orphans
”. The node can be given its
own name like this:
ngctl name bge0:orphans src0
After which it can be referred to as
“
src0:
”.
Once created, packets can be sent to the node as raw binary data. Each packet
must be delivered in a separate netgraph message.
The following example uses a short Perl script to convert the hex representation
of an ICMP packet to binary and deliver it to the
source
node's
input hook via
nghook(8):
perl -pe 's/(..)[ \t\n]*/chr(hex($1))/ge' <<EOF | nghook src0: input
ff ff ff ff ff ff 00 00 00 00 00 00 08 00 45 00
00 54 cb 13 00 00 40 01 b9 87 c0 a8 2b 65 0a 00
00 01 08 00 f8 d0 c9 76 00 00 45 37 01 73 00 01
04 0a 08 09 0a 0b 0c 0d 0e 0f 10 11 12 13 14 15
16 17 18 19 1a 1b 1c 1d 1e 1f 20 21 22 23 24 25
26 27 28 29 2a 2b 2c 2d 2e 2f 30 31 32 33 34 35
36 37
EOF
To check that the node has queued these packets you can get the node statistics:
ngctl msg bge0:orphans getstats
Args: { queueOctets=64 queueFrames=1 }
Send as many packets as required out the
output hook:
ngctl msg bge0:orphans start 16
Either wait for them to be sent (periodically fetching stats if desired) or send
the stop message:
ngctl msg bge0:orphans stop
Check the statistics (here we use
getclrstats to also clear
the statistics):
ngctl msg bge0:orphans getclrstats
Args: { outOctets=1024 outFrames=16 queueOctets=64 queueFrames=1
startTime={ tv_sec=1035305880 tv_usec=758036 } endTime={ tv_sec=1035305880
tv_usec=759041 } elapsedTime={ tv_usec=1005 } }
The times are from
struct timevals, the
tv_sec field is seconds since the Epoch and can be
converted into a date string via TCL's [clock format] or via the
date(1) command:
date -r 1035305880
Tue Oct 22 12:58:00 EDT 2002
SEE ALSO¶
netgraph(4),
ng_echo(4),
ng_hole(4),
ng_tee(4),
ngctl(8),
nghook(8)
HISTORY¶
The
ng_source node type was implemented in
FreeBSD 4.8.
AUTHORS¶
Dave Chapeskie