Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Remove defunct email address from header as well.

Add "setcounter" and "getcounter" messages, providing the the ability
to embed up to four counters in outgoing packets. The message specifies
the offset at which the counter should be inserted as well as the
parameters of the counter.

Example usage:

ngctl msg src0: setcounter \
'{ index=0 offset=0x40 flags=1 width=4 increment=1 max_val=12345 }'

Sponsored by: Sandvine Incorporated

Add "settimestamp" and "gettimestamp" messages, providing the the ability
to embed a timestamp (struct timeval) in outgoing packets. The message
specifies the offset at which the timestamp should be inserted.

NG_SOURCE(4) gives an example usage that queues an ICMP packet. Using that
example, the following command will insert a timestamp in the ICMP's data
payload:

ngctl msg src0: settimestamp '{ offset=0x2a flags=1 }'

Sponsored by: Sandvine Incorporated

Implement an upper limit for packets per second sent by node.

Major overhaul and cleanup of ng_source node.

Functional changes:
- Cut struct source_hookinfo. Just use hook_p pointer.
- Remove "start_now" command. "start" command now requires number of
packets to send as argument. "start" command actually starts sending.
Move the code that actually starts sending from ng_source_rcvmsg()
to ng_source_start().
- Remove check for NG_SOURCE_ACTIVE in ng_source_stop(). We can be called
with flag cleared (see begin of ng_source_intr()).
- If NG_SEND_DATA_ONLY() use log(LOG_DEBUG) instead of printf(). Otherwise
we will *flood* console.
- Add ng_connect_t method, which sends NGM_ETHER_GET_IFNAME command
to "output" hook. Cut ng_source_request_output_ifp(). Refactor
ng_source_store_output_ifp() to use ifunit() and don't muck through
interface list.
- Add "setiface" command, which gives ability to configure interface
in case when ng_source_connect() failed. This happens, when we are not
connected directly to ng_ether(4) node.
- Remove KASSERTs, which can never fire.
- Don't check for M_PKTHDR in rcvdata method. netgraph(4) does this
for us.

Style:
- Assign sc_p = NG_NODE_PRIVATE(node) in declaration, to be
consistent with style of other nodes.
- Sort variables.
- u_intXX -> uintXX.
- Dots at ends of comments.

Sponsored by: Rambler

Make some basic grammar and style fixes to ng_source.c and ng_source.h.
The latter was particularly violated by someone's editor in the past, due
to an effect I like to call "premature linewrapping."

/* -> /*- for license, minor formatting changes

Define the new command NGM_SOURCE_START_NOW to allow generation of
traffic for non-ethernet hooks. This commit should have been packaged
with the commit to ng_source.c.

Use a single style of multiple inclusion protection for Netgraph headers.

Reviewed by: archie, harti, emax

Add the netgraph 'source' module.
This is NOT YET CONVERTED TO -current.
This node is a source for preprogrammed packets at a known rate for testing.

I will convert it to -current "in place" but will MFC teh original
pre-conversion variant as that is what is originally submitted.
Man page my me, info from Dave's README.

Submitted by: Dave Chapeskie <dchapeskie@SANDVINE.com>
Obtained from: Sandvine inc.
MFC after: 1 week