How to do a RTM_GETNSID?

[TheDiveO]

I'm trying to do a IPRoute().nlm_request(req, RTM_GETNSID). I'm lost as to how to correctly build the request message and send it, even after reading several source code files (and documentation) of pyroute2 for some hours. What I think I understood is this:

req=nsidmsg()
req['family']=socket.AF_UNSPEC
req['attrs'] = [('NETNSA_FD', netnsf.fileno())]
res=IPRoute().nlm_request(req, RTM_GETNSID)

...but is this correct at all? The problem is that I always get a dump of all NETNSA_NSID in form of RTM_NEWNSID events. I would expect a reply of exactly one NETNSA_NSID, the one corresponding with the NETNSA_FD, where the fd is the one from /proc/12345/ns/net.

What am I doing wrong here?

[TheDiveO]

It seems as if there's a problem with the request encoding:

I'm trying to do a `IPRoute().nlm_request(req, RTM_GETNSID)`. I'm using pyroute2 0.5.0.

from pyroute2 import IPRoute
import socket
from pyroute2.netlink import NLM_F_REQUEST
import pyroute2.netlink.rtnl as rtnl
import pyroute2.netlink.rtnl.nsidmsg as nsidmsg

netstack = IPRoute()
with open('/proc/{}/ns/net'.format(12345), "r") as netnsf: # PID 12345
    req = nsidmsg.nsidmsg()
    req['rtgen_family'] = 0

    req['attrs'] = [('NETNSA_FD', netnsf.fileno())]

    req.encode()
    ret = netstack.nlm_request(req, rtnl.RTM_GETNSID, NLM_F_REQUEST)

The request fails with error 22, invalid argument. Strace shows this, indicating that only 25 octets are indicated in the header:

sendto(5, {{len=25, type=0x5a /* NLMSG_??? */, flags=NLM_F_REQUEST, seq=255, pid=31204}, "\x00\x00\x00\x00\x08\x00\x03\x00\x06"}, 28, 0, {sa_family=AF_NETLINK, nl_pid=0, nl_groups=00000000}, 12) = 28

As the FD should be encoded as uint32, I would expect at least three more octets for the FD.

Comparing this to a RTM_GETNSID request from `lsns` I see that the request should have a length of 28.

[Peter Saveliev]

> What am I doing wrong here?

Nothing wrong, it should work. Let me play a bit to investigate.

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[Peter Saveliev]

but pls keep in mind that the functionality isn't released yet :) I just hadn't time to complete it. Will do asap.

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[TheDiveO]

Didn't realize that I did directly hit, without taking aim, some bleeding edge spot. :) At least I have a somewhat terrible hack to get it working, that's what hacks are supposedly for. Thank you for looking into it!