On Wed, Nov 15, 2017 at 11:59:18AM +0900, Masatake YAMATO wrote:
> Linux network subsystem assigns an unique integer to a network
> namespace.
>
> term0# ip netns add UTIL-LINUX-LSNS-TEST-NS
> term0# ip netns list
> UTIL-LINUX-LSNS-TEST-NS
> term0# ip link add name lsns-vetha type veth peer name lsns-vethb
> term0 # ip link set lsns-vethb netns UTIL-LINUX-LSNS-TEST-NS
> term0# ip netns list
> UTIL-LINUX-LSNS-TEST-NS (id: 0)
> term0# ip link show dev lsns-vetha
> 230: lsns-vetha@if229: <BROADCAST,MULTICAST> mtu 1500 qdisc noop ...
> link/ether 3e:27:68:ba:b3:95 brd ff:ff:ff:ff:ff:ff link-netnsid 0
> In this example 0 is assigned to UTIL-LINUX-LSNS-TEST-NS net namespace.
> The name, UTIL-LINUX-LSNS-TEST-NS, and it semantics is given and defined
> by iproute2 in userland; and nothing to do with util-linux.
>
> However, the id, 0, is managed in linux kernel. If lsns can show
> the ids, it helps users understand the state of network namespaces.
Where iproute2 stores the logical name of the namespace (e.g.
UTIL-LINUX-LSNS-TEST-NS)? Cannot we read it? :-)
> +static int netnsid_xasputs(char **str, int netnsid)
> +{
> + if (netnsid >= 0)
> + return xasprintf(&str, "%d", netnsid);
> +#ifdef NETNSA_NSID_NOT_ASSIGNED
> + else if (netnsid == NETNSA_NSID_NOT_ASSIGNED)
> + return xasprintf(&str, "%s", "unassigned");
> +#endif
> + else
> + return xasprintf(&str, "%s", "n/a");
We usually use blank space rather than n/a if data are not available.
In this case "return NULL;" is good enough.
> +#ifdef HAVE_LINUX_NET_NAMESPACE_H
> + netlink_fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
> +#endif
> + if (netlink_fd < 0)
> + netlink_fd = -errno;
I guess this if() is unnecessary. The rest of the code check for
netlink_fd < 0.
It would be also nice to call socket() only if NETNSID column is wanted.
What about to add NETNSID collumn to the default output only if "--type net"
specified on lsns command line?
I'm ready to do all the changes (you don't have to resend the patch).
Karel
--
Karel Zak <kzak@xxxxxxxxxx>
http://karelzak.blogspot.com
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