[Qemu-devel] [PATCH RFC 0/4] Dumping traffic when using netdev devices

[Miguel Di Ciurcio Filho <miguel.filho@gmail.com>]

Hello,

This is a prototype suggestion. I mostly copied and pasted the code from
net/dump.c into net.c and made some adjustments. There is no command line
parsing involved yet, just the internals and small changes in net/tap.c and
net/slirp.c do make the thing work.

In my tests, using tap as backend, e1000 as a guest device and running iperf from
guest to host, the overhead of dumping the traffic caused a loss of around 30%
of performance.

I opened the dumped files in wireshark and they looked fine. When using slirp
all requests were dumped fine too.

Bugs/limitations:
- I have no clue on how to deal with tap+vhost, is it necessary?
- When using virtio-net, I'm not sure how to handle iovec when vnet_hdr=on
- Create a function to add dump to a netdev on the fly, is it necessary?
- Handle cleanups

Miguel Di Ciurcio Filho (4):
  net/dump: Make pcap structures public
  net: Introduce NetClientDump and auxiliary functions
  net/tap: Suggested support for NetClientDump
  net/slirp: Suggested support for NetClientDump

 net.c         |   90 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 net.h         |    8 +++++
 net/dump.c    |   21 -------------
 net/dump.h    |   21 +++++++++++++
 net/slirp.c   |    3 ++
 net/tap.c     |    3 ++
 qemu-common.h |    1 +
 7 files changed, 126 insertions(+), 21 deletions(-)