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route/link: return -NLE_OPNOTSUPP in rtnl_link_get_kernel() for old kernels

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Older kernels without patch a3d1289126e7b14307074b76bf1677015ea5036f do
not support rtnl_getlink() by ifname. Detect this situation and fail
with -NLE_OPNOTSUPP instead of -NLE_INVAL.

This changes behavior in returning a different error code for this
case.

Acked-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: Thomas Haller <thaller@redhat.com>
This commit is contained in:
Thomas Haller 2014-11-26 18:17:16 +01:00
parent 8b023fd441
commit b54775d316
3 changed files with 26 additions and 2 deletions
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8
include/netlink/utils.h
View file

@ -113,6 +113,14 @@ enum {
NL_CAPABILITY_NL_CONNECT_RETRY_GENERATE_PORT_ON_ADDRINUSE = 4,
#define NL_CAPABILITY_NL_CONNECT_RETRY_GENERATE_PORT_ON_ADDRINUSE NL_CAPABILITY_NL_CONNECT_RETRY_GENERATE_PORT_ON_ADDRINUSE
/**
* Indicate that rtnl_link_get_kernel() fails with -NLE_OPNOTSUPP in case
* of older kernals not supporting lookup by ifname. This changes behavior
* from returning -NLE_INVAL to return -NLE_OPNOTSUPP.
*/
NL_CAPABILITY_ROUTE_LINK_GET_KERNEL_FAIL_OPNOTSUPP = 5,
#define NL_CAPABILITY_ROUTE_LINK_GET_KERNEL_FAIL_OPNOTSUPP NL_CAPABILITY_ROUTE_LINK_GET_KERNEL_FAIL_OPNOTSUPP
__NL_CAPABILITY_MAX
#define NL_CAPABILITY_MAX (__NL_CAPABILITY_MAX - 1)
};

18
lib/route/link.c
View file

@ -1160,6 +1160,11 @@ nla_put_failure:
* pointer or -NLE_OBJ_NOTFOUND is returned if no matching link was
* found.
*
* Older kernels do not support lookup by name. In that case, libnl
* will fail with -NLE_OPNOTSUPP. Note that previous version of libnl
* failed in this case with -NLE_INVAL. You can check libnl behavior
* using NL_CAPABILITY_ROUTE_LINK_GET_KERNEL_FAIL_OPNOTSUPP capability.
*
* @route_doc{link_direct_lookup, Lookup Single Link (Direct Lookup)}
* @return 0 on success or a negative error code.
*/
@ -1169,6 +1174,7 @@ int rtnl_link_get_kernel(struct nl_sock *sk, int ifindex, const char *name,
struct nl_msg *msg = NULL;
struct nl_object *obj;
int err;
int syserr;
if ((err = rtnl_link_build_get_request(ifindex, name, &msg)) < 0)
return err;
@ -1178,8 +1184,18 @@ int rtnl_link_get_kernel(struct nl_sock *sk, int ifindex, const char *name,
if (err < 0)
return err;
if ((err = nl_pickup(sk, link_msg_parser, &obj)) < 0)
if ((err = nl_pickup_keep_syserr(sk, link_msg_parser, &obj, &syserr)) < 0) {
if (syserr == -EINVAL &&
ifindex <= 0 &&
name && *name) {
/* Older kernels do not support lookup by ifname. This was added
* by commit kernel a3d1289126e7b14307074b76bf1677015ea5036f .
* Detect this error case and return NLE_OPNOTSUPP instead of
* NLE_INVAL. */
return -NLE_OPNOTSUPP;
}
return err;
}
/* We have used link_msg_parser(), object is definitely a link */
*result = (struct rtnl_link *) obj;

2
lib/utils.c
View file

@ -1148,7 +1148,7 @@ int nl_has_capability (int capability)
NL_CAPABILITY_ROUTE_LINK_VETH_GET_PEER_OWN_REFERENCE,
NL_CAPABILITY_ROUTE_LINK_CLS_ADD_ACT_OWN_REFERENCE,
NL_CAPABILITY_NL_CONNECT_RETRY_GENERATE_PORT_ON_ADDRINUSE,
0,
NL_CAPABILITY_ROUTE_LINK_GET_KERNEL_FAIL_OPNOTSUPP,
0,
0,
0),