netdev - Re: iproute2 bug in json output for encap

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Date:   Fri, 14 Apr 2023 08:21:03 -0700
From:   Stephen Hemminger <stephen@...workplumber.org>
To:     Lars Ekman <uablrek@...il.com>
Cc:     netdev@...r.kernel.org
Subject: Re: iproute2 bug in json output for encap

On Fri, 14 Apr 2023 10:29:15 +0200
Lars Ekman <uablrek@...il.com> wrote:

> The destination is lost in json printout and replaced by the encap 
> destination. The destination can even be ipv6 for an ipv4 route.
> 
> Example:
> 
> vm-002 ~ # ip route add 10.0.0.0/24 proto 5 dev ip6tnl6 encap ip6 dst 
> fd00::192.168.2.221
> vm-002 ~ # ip route show proto 5
> 10.0.0.0/24  encap ip6 id 0 src :: dst fd00::c0a8:2dd hoplimit 0 tc 0 
> dev ip6tnl6 scope link
> vm-002 ~ # ip -j route show proto 5 | jq
> [
>    {
>      "dst": "fd00::c0a8:2dd",
>      "encap": "ip6",
>      "id": 0,
>      "src": "::",
>      "hoplimit": 0,
>      "tc": 0,
>      "dev": "ip6tnl6",
>      "scope": "link",
>      "flags": []
>    }
> ]
> 

Both JSON and regular output show the same address which is coming from
the kernel.  I.e not a JSON problem. Also, you don't need to use jq
ip has -p flag to pretty print.

I can not reproduce this with current kernel and iproute2.
# ip route add 192.168.11.0/24 proto 5 dev dummy0 encap ip6 dst fd00::192.168.2.221

# ip route show proto 5
192.168.11.0/24  encap ip6 id 0 src :: dst fd00::c0a8:2dd hoplimit 0 tc 0 dev dummy0 scope link 

# ip -j -p route show proto 5
[ {
        "dst": "192.168.11.0/24",
        "encap": "ip6",
        "id": 0,
        "src": "::",
        "dst": "fd00::c0a8:2dd",
        "hoplimit": 0,
        "tc": 0,
        "dev": "dummy0",
        "scope": "link",
        "flags": [ ]
    } ]


# ip -V
ip utility, iproute2-6.1.0, libbpf 1.1.0
# uname -r
6.1.0-7-amd64