Re: [B.A.T.M.A.N.] [RFC 1/3] batman-adv: bandwidth meter implementation

The bandwith meter module is a simple, kernel-space replacement for bandwith
measurements tool like iperf and netper. It is intended to approximate TCP
behaviour.

It is invoked through ``batctl bw": the protocol is connection oriented,
with cumulative acknowledgment and sliding window. Sender keeps a timeout,
which is checked by a worker function regoularly invoked through the
workqueue mechanism. If the timeout is expired at the time worker is
executed, the whole window is re-transmitted.

Struct bw_vars, one for each connection, are collected into a linked list.
Thus access to them is protected with a spinlock.

Another spinlock prevents more than one instance of multiple_send to run
concurrently. Ack code is mutually exclusive (two ack handler cannot run at
the same time for differnent acks), but they are not mutually exclusive
with send_remaining_window, that is to say the ack handler shifts the
window ``while" send_remaining_window is running. Maybe some atomic
variable (window_first) is needed to avoid problems.

When the test is over, the results are returned to batctl through a call to
the function batadv_socket_receive_packet(), before freeing struct
batadv_bw_vars.

The function only accepts struct batadv_icmp_packet_rr, so that structure is
used and a cast is done to struct batadv_bw_result.

The test interruptable with CTRL-C. A receiver side timeout avoids
unlimited waitings for sender packets: after one second of inactivity, the
receiver abort the ongoing test.

Signed-off-by: Edo Monticelli <redacted>
---
 Makefile         |    2 +-
 Makefile.kbuild  |    1 +
 bw_meter.c       |  513
++++++++++++++++++++++++++++++++++++++++++++++++++++++ bw_meter.h       |  
 7 +
 icmp_socket.c    |   18 ++
 main.c           |    2 +
 packet.h         |   22 ++-
 routing.c        |   15 ++-
 soft-interface.c |    5 +
 types.h          |   36 ++++
 10 files changed, 614 insertions(+), 7 deletions(-)
 create mode 100644 bw_meter.c
 create mode 100644 bw_meter.h

diff --git a/Makefile b/Makefile
index bd8d30c..12aebe5 100644
--- a/Makefile
+++ b/Makefile

@@ -20,7 +20,7 @@

 # changing the CONFIG_* line to 'y' enables the related feature
 # B.A.T.M.A.N. debugging:
-export CONFIG_BATMAN_ADV_DEBUG=n
+export CONFIG_BATMAN_ADV_DEBUG=y
 # B.A.T.M.A.N. bridge loop avoidance:
 export CONFIG_BATMAN_ADV_BLA=y