[Bug report] Unable to remove 'default' routes using the CLI tools

[Roopa Prabhu]

Thanks tony for the commit id.

I will try to reproduce your problem today.

On 3/18/13 10:32 AM, Tony Cheneau wrote:
> Hello,
>
> I just ran a git-bisect and can new affirm that the issue has been
> introduced with commit a2207c7beb80050671d209650aaaeba429658e49 (just
> before version 3.2.15). I joined a patch, that disable the issue for
> now, but I don't believe it should be applied to the tree, as it does
> not fix the real problem. Unfortunately, I don't have time or in-depth
> knowledge of the code to actually fix the issue properly.
>
> Please note that I was only interested in the "route" submodule, so it
> is the only one I tested. It could also affect some other submodules
> (given previous commits seem to affect similar portions of the code in
> those others submodules).
>
> I'd be interested to know if I'm the only one having this issue.
>
> Regards,
> Tony
>
> P.-S.: I cc'ed Roopa, because both of us had a private email exchange
> about this topic.
>
> Le 2013-02-05 23:43, Tony Cheneau a écrit :
>> Hello,
>>
>> For my own purposes, I'm building a bunch of python wrappers around
>> libraries exposed by CLI tools (that is the functions exposed in the
>> netlink/cli directory). To be more precise, I'm using cython to glue
>> the libnl C code within a python wrapper. While performing my tests, I
>> found out a odd behavior when playing with default routes: I could not
>> always remove them. To me, it qualifies as a bug, but it might be an
>> intended behavior. This issue is also present with the nl-route-delete
>> binary, so I'll use this tool for my bug report. Finally, I must add
>> that I'm using the current git tree tip.
>>
>> So, first step is to add multiple default routes (lines starting with
>> # are indicates the command I inputted):
>> # ./nl-route-add -d default -n via=10.0.0.3,dev=eth0
>> Added inet default via 10.0.0.3 dev eth0
>> # ./nl-route-add -d default -n via=10.0.0.2,dev=eth0
>> Added inet default via 10.0.0.2 dev eth0
>> # ./nl-route-add -d default -n via=10.0.0.1,dev=eth0
>> Added inet default via 10.0.0.1 dev eth0
>>
>> Then I try listing current routes:
>> # ./nl-route-list|grep default
>> inet default table main type unicast via 10.0.20.200 dev eth0
>> inet6 default table unspec type unreachable via dev lo
>>
>> I find it weird enough that the route does not show up. Only the
>> initial route to my default gateway shows up (it was set before I run
>> any of the previous commands).
>> However, if I try adding a route again, I obtain the following
>> message (that would indicate that the previous commands went through):
>> # ./nl-route-add -d default -n via=10.0.0.1,dev=eth0
>> Error: Unable to add route: Object exists
>>
>> Now, this is the part that motivates me to write this bug report, if
>> I try to remove the default routes using symmetrical command
>> "nl-route-delete", I obtain the following:
>> # ./nl-route-delete -d default -n via=10.0.0.3,dev=eth0
>> Deleted 0 routes
>> # ./nl-route-delete -d default -n via=10.0.0.2,dev=eth0
>> Deleted 0 routes
>> # ./nl-route-delete -d default -n via=10.0.0.1,dev=eth0
>> Deleted 0 routes
>>
>> However, if I remove the next-hop selector, it works (I omitted the
>> part when I removed my default gateway, because I lost connection on
>> this one and could not retrieve the output):
>> # ./nl-route-delete -d default
>> Deleted inet default table main type unicast via 10.0.0.3 dev eth0
>> Deleted 1 routes
>> # ./nl-route-delete -d default
>> Deleted inet default table main type unicast via 10.0.0.2 dev eth0
>> Deleted 1 routes
>> # ./nl-route-delete -d default
>> Deleted inet default table main type unicast via 10.0.0.1 dev eth0
>> Deleted 1 routes
>>
>> It also works if I reverse the ordering when removing routes (when no
>> default gateway is set):
>> # ./nl-route-add -d default -n via=10.0.0.3,dev=eth0
>> Added inet default via 10.0.0.3 dev eth0
>> # ./nl-route-add -d default -n via=10.0.0.2,dev=eth0
>> Added inet default via 10.0.0.2 dev eth0
>> # ./nl-route-add -d default -n via=10.0.0.1,dev=eth0
>> Added inet default via 10.0.0.1 dev eth0
>> # ./nl-route-delete -d default -n via=10.0.0.1,dev=eth0
>> Deleted 0 routes
>> # ./nl-route-delete -d default -n via=10.0.0.3
>> Deleted inet default table main type unicast via 10.0.0.3 dev eth0
>> Deleted 1 routes
>> # ./nl-route-delete -d default -n via=10.0.0.2
>> Deleted inet default table main type unicast via 10.0.0.2 dev eth0
>> Deleted 1 routes
>> # ./nl-route-delete -d default -n via=10.0.0.1
>> Deleted inet default table main type unicast via 10.0.0.1 dev eth0
>> Deleted 1 routes
>>
>> The same phenomena seems to occur when using IPv6 addresses.
>>
>> (As a side note, I wanted to add that I'm aware of the various python
>> bindings existing for libnl, but, to the best of my knowledge, none of
>> them seems to control the netlink "route" sub-system that I need.)
>>
>> Regards,
>> Tony Cheneau
>>
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