netlink: Make nl_*_dup() use a separate datagram for each request

nl_req() is designed to handle a single netlink request message: it only
receives a single reply datagram for the request, and only waits for a
single NLMSG_DONE or NLMSG_ERROR message at the beginning to clear out
things from previous requests.

However, in both nl_addr_dup() and nl_route_dup() we can send multiple
request messages as a single datagram, with a single nl_req() call.
This can easily mean that the replies nl_req() collects get out of
sync with requests.  We only get away with this because after we call
these functions we don't make any netlink calls where we need to parse
the replies.

This is fragile, so alter nl_*_dup() to make an nl_req() call for each
address it is adding in the target namespace.

For nl_route_dup() this fixes an additional minor problem: because
routes can have dependencies, some of the route add requests might
fail on the first attempt, so we need to repeat the requests a number
of times.  When we did that, we weren't updating the sequence number
on each new attempt.  This works, but not updating the sequence number
for each new request isn't ideal.  Now that we're making the requests
one at a time, it's easier to make sure we update the sequence number
each time.

Link: https://bugs.passt.top/show_bug.cgi?id=67
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

0 files changed, 0 insertions, 0 deletions