netdev - Re: [PATCH iproute2] ip_tunnel: determine tunnel address family from the tunnel type

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Date:	Thu, 26 Nov 2015 18:22:05 +0200
From:	Konstantin Shemyak <konstantin@...myak.com>
To:	Stephen Hemminger <shemming@...cade.com>
Cc:	"netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: [PATCH iproute2] ip_tunnel: determine tunnel address family from
 the tunnel type

On 24.11.2015 02:26, Stephen Hemminger wrote:
> On Thu, 12 Nov 2015 21:10:08 +0000
> Konstantin Shemyak <konstantin@...myak.com> wrote:
>
>> When creating an IP tunnel over IPv6, the address family must be passed in
>> the option, e.g.
>>
>> ip -6 tunnel add mode ip6gre local 1::1 remote 2::2
>>
>> This makes it impossible to create both IPv4 and IPv6 tunnels in one batch.
>>
>> In fact the address family option is redundant here, as each tunnel mode is
>> relevant for only one address family.
>> The patch determines whether the applicable address family is AF_INET6
>> instead of the default AF_INET and makes the "-6" option unnecessary for
>> "ip tunnel add".
>>
>> Signed-off-by: Konstantin Shemyak <konstantin@...myak.com>
>> ---
>>   ip/iptunnel.c                          | 26 ++++++++++++++++++++++++++
>>   testsuite/tests/ip/tunnel/add_tunnel.t | 14 ++++++++++++++
>>   2 files changed, 40 insertions(+)
>>   create mode 100755 testsuite/tests/ip/tunnel/add_tunnel.t
>>
>> diff --git a/ip/iptunnel.c b/ip/iptunnel.c
>> index 78fa988..7826a37 100644
>> --- a/ip/iptunnel.c
>> +++ b/ip/iptunnel.c
>> @@ -629,8 +629,34 @@ static int do_6rd(int argc, char **argv)
>>          return tnl_6rd_ioctl(cmd, medium, &ip6rd);
>>   }
>>
>> +static int tunnel_mode_is_ipv6(char *tunnel_mode) {
>> +       char *ipv6_modes[] = {
>> +               "ipv6/ipv6", "ip6ip6",
>> +               "vti6",
>> +               "ip/ipv6", "ipv4/ipv6", "ipip6", "ip4ip6",
>> +               "ip6gre", "gre/ipv6",
>> +               "any/ipv6", "any"
>> +       };
>> +       int i;
>> +
>> +       for (i = 0; i < sizeof(ipv6_modes) / sizeof(char *); i++) {
>> +               if (strcmp(ipv6_modes[i], tunnel_mode) == 0)
>> +                       return 1;
>> +       }
>> +       return 0;
>> +}
>> +
>
> The ipv6_modes table should be static const.

Thank you for the note! attached the corrected patch.

> Also is it possible to use strstr for ipv6 and ip6 or even strchr(tunnel_mode, '6')
> to simplify this?

There is IPv6 tunnel mode 'any', and IPv4 tunnel mode 'ipv6/ip' (aka 
'sit'). It looks to me that attempts to find some substring match
would not make the code much shorter, but definitely less readable.

Konstantin Shemyak.

View attachment "0001-Tunnel-address-family-is-determined-from-the-tunnel-.patch" of type "text/x-patch" (2345 bytes)