netdev - Re: [PATCH iproute2] Add "show" subcommand to "ip fou"

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Date:   Fri, 3 Nov 2017 10:25:37 -0700
From:   Tom Herbert <tom@...bertland.com>
To:     Greg Greenway <ggreenway@...le.com>
Cc:     Stephen Hemminger <stephen@...workplumber.org>,
        Linux Kernel Network Developers <netdev@...r.kernel.org>
Subject: Re: [PATCH iproute2] Add "show" subcommand to "ip fou"

On Fri, Nov 3, 2017 at 10:19 AM, Greg Greenway <ggreenway@...le.com> wrote:
> On Nov 1, 2017, at 2:03 PM, Stephen Hemminger <stephen@...workplumber.org> wrote:
>>
>> On Tue, 31 Oct 2017 13:00:47 -0700
>> Greg Greenway <ggreenway@...le.com> wrote:
>>
>>> +    if (tb[FOU_ATTR_AF]) {
>>> +            family = rta_getattr_u8(tb[FOU_ATTR_AF]);
>>> +            if (family == AF_INET)
>>> +                    family_str = "AF_INET";
>>> +            else if (family == AF_INET6)
>>> +                    family_str = "AF_INET6";
>>> +            else
>>> +                    family_str = "unknown";
>>> +            fprintf(fp, "af %s ", family_str);
>>
>> The unwritten rule for ip commands is that the show function
>> must format the output with same command syntax as the other commands set/add/delete.
>> Since there is no "af AF_INET" option to ip fou, this breaks that convention.
>> Either ignore the address family, change the add command, or output with same
>> syntax (-6); preferably the latter.
>
> That makes sense.  Here's a corrected version.  It also avoids a trailing-space in the output.
>
> From: Greg Greenway <ggreenway@...le.com>
> Date: Tue, 31 Oct 2017 12:47:35 -0700
> Subject: [PATCH] Add "show" subcommand to "ip fou".
>
> Sample output:
>
> $ sudo ./ip/ip fou add port 111 ipproto 11
> $ sudo ./ip/ip fou add port 222 ipproto 22 -6
> $ ./ip/ip fou show
> port 222 ipproto 22 -6
> port 111 ipproto 11
>
> Signed-off-by: Greg Greenway <ggreenway@...le.com>
> ---
>  ip/ipfou.c | 60 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 60 insertions(+)
>
> diff --git a/ip/ipfou.c b/ip/ipfou.c
> index 00dbe15..ecbaf11 100644
> --- a/ip/ipfou.c
> +++ b/ip/ipfou.c
> @@ -28,6 +28,7 @@ static void usage(void)
>         fprintf(stderr, "Usage: ip fou add port PORT "
>                 "{ ipproto PROTO  | gue } [ -6 ]\n");
>         fprintf(stderr, "       ip fou del port PORT [ -6 ]\n");
> +       fprintf(stderr, "       ip fou show\n");
>         fprintf(stderr, "\n");
>         fprintf(stderr, "Where: PROTO { ipproto-name | 1..255 }\n");
>         fprintf(stderr, "       PORT { 1..65535 }\n");
> @@ -134,6 +135,63 @@ static int do_del(int argc, char **argv)
>         return 0;
>  }
>
> +static int print_fou_mapping(const struct sockaddr_nl *who,
> +                                struct nlmsghdr *n, void *arg)
> +{
> +       FILE *fp = (FILE *)arg;
> +       struct genlmsghdr *ghdr;
> +       struct rtattr *tb[FOU_ATTR_MAX + 1];
> +       int len = n->nlmsg_len;
> +       unsigned family;
> +
> +       if (n->nlmsg_type != genl_family)
> +               return 0;
> +
> +       len -= NLMSG_LENGTH(GENL_HDRLEN);
> +       if (len < 0)
> +               return -1;
> +
> +       ghdr = NLMSG_DATA(n);
> +       parse_rtattr(tb, FOU_ATTR_MAX, (void *) ghdr + GENL_HDRLEN, len);
> +
> +       if (tb[FOU_ATTR_PORT])
> +               fprintf(fp, "port %u", ntohs(rta_getattr_u16(tb[FOU_ATTR_PORT])));
> +       if (tb[FOU_ATTR_TYPE] && rta_getattr_u8(tb[FOU_ATTR_TYPE]) == FOU_ENCAP_GUE)
> +               fprintf(fp, " gue");
> +       else if (tb[FOU_ATTR_IPPROTO])
> +               fprintf(fp, " ipproto %u", rta_getattr_u8(tb[FOU_ATTR_IPPROTO]));
> +       if (tb[FOU_ATTR_AF]) {
> +               family = rta_getattr_u8(tb[FOU_ATTR_AF]);
> +               if (family == AF_INET6)
> +                       fprintf(fp, " -6");
> +       }
> +       fprintf(fp, "\n");
> +
> +       return 0;
> +}
> +
> +static int do_show(int argc, char **argv)
> +{
> +       FOU_REQUEST(req, 4096, FOU_CMD_GET, NLM_F_REQUEST | NLM_F_DUMP);
> +
> +       if (argc > 0) {
> +               fprintf(stderr, "\"ip fou show\" does not take any arguments.\n");
> +               return -1;
> +       }
> +
> +       if (rtnl_send(&genl_rth, &req.n, req.n.nlmsg_len) < 0) {
> +               perror("Cannot send show request");
> +               exit(1);
> +       }
> +
> +       if (rtnl_dump_filter(&genl_rth, print_fou_mapping, stdout) < 0) {
> +               fprintf(stderr, "Dump terminated\n");
> +               return 1;
> +       }
> +
> +       return 0;
> +}
> +
>  int do_ipfou(int argc, char **argv)
>  {
>         if (argc < 1)
> @@ -149,6 +207,8 @@ int do_ipfou(int argc, char **argv)
>                 return do_add(argc-1, argv+1);
>         if (matches(*argv, "delete") == 0)
>                 return do_del(argc-1, argv+1);
> +       if (matches(*argv, "show") == 0)
> +               return do_show(argc-1, argv+1);
>         fprintf(stderr, "Command \"%s\" is unknown, try \"ip fou help\".\n", *argv);
>         exit(-1);
>  }
> --
> 2.7.4
>
Acked-by: Tom Herbert <tom@...bertland.com>