diff --git a/include/netlink/netlink.h b/include/netlink/netlink.h index 61656b3..f8f2082 100644 --- a/include/netlink/netlink.h +++ b/include/netlink/netlink.h @@ -87,6 +87,11 @@ extern int nl_pickup(struct nl_sock *, struct nlmsghdr *, struct nl_parser_param *), struct nl_object **); +extern int nl_pickup_keep_syserr(struct nl_sock *sk, + int (*parser)(struct nl_cache_ops *, struct sockaddr_nl *, + struct nlmsghdr *, struct nl_parser_param *), + struct nl_object **result, + int *syserror); /* Netlink Family Translations */ extern char * nl_nlfamily2str(int, char *, size_t); extern int nl_str2nlfamily(const char *); diff --git a/include/netlink/utils.h b/include/netlink/utils.h index 6b4b787..431502f 100644 --- a/include/netlink/utils.h +++ b/include/netlink/utils.h @@ -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) }; diff --git a/lib/nl.c b/lib/nl.c index 25fd59c..fade848 100644 --- a/lib/nl.c +++ b/lib/nl.c @@ -867,7 +867,7 @@ continue_reading: interrupted = 1; } } - + /* Other side wishes to see an ack for this message */ if (hdr->nlmsg_flags & NLM_F_ACK) { if (cb->cb_set[NL_CB_SEND_ACK]) @@ -955,7 +955,7 @@ skip: err = 0; hdr = nlmsg_next(hdr, &n); } - + nlmsg_free(msg); free(buf); free(creds); @@ -1077,6 +1077,7 @@ struct pickup_param int (*parser)(struct nl_cache_ops *, struct sockaddr_nl *, struct nlmsghdr *, struct nl_parser_param *); struct nl_object *result; + int *syserror; }; static int __store_answer(struct nl_object *obj, struct nl_parser_param *p) @@ -1103,25 +1104,50 @@ static int __pickup_answer(struct nl_msg *msg, void *arg) return pp->parser(NULL, &msg->nm_src, msg->nm_nlh, &parse_arg); } +static int __pickup_answer_syserr(struct sockaddr_nl *nla, struct nlmsgerr *nlerr, void *arg) +{ + *(((struct pickup_param *) arg)->syserror) = nlerr->error; + + return -nl_syserr2nlerr(nlerr->error); +} + /** @endcond */ /** * Pickup netlink answer, parse is and return object - * @arg sk Netlink socket - * @arg parser Parser function to parse answer - * @arg result Result pointer to return parsed object + * @arg sk Netlink socket + * @arg parser Parser function to parse answer + * @arg result Result pointer to return parsed object * * @return 0 on success or a negative error code. */ int nl_pickup(struct nl_sock *sk, - int (*parser)(struct nl_cache_ops *, struct sockaddr_nl *, - struct nlmsghdr *, struct nl_parser_param *), - struct nl_object **result) + int (*parser)(struct nl_cache_ops *, struct sockaddr_nl *, + struct nlmsghdr *, struct nl_parser_param *), + struct nl_object **result) +{ + return nl_pickup_keep_syserr(sk, parser, result, NULL); +} + +/** + * Pickup netlink answer, parse is and return object with preserving system error + * @arg sk Netlink socket + * @arg parser Parser function to parse answer + * @arg result Result pointer to return parsed object + * @arg syserr Result pointer for the system error in case of failure + * + * @return 0 on success or a negative error code. + */ +int nl_pickup_keep_syserr(struct nl_sock *sk, + int (*parser)(struct nl_cache_ops *, struct sockaddr_nl *, + struct nlmsghdr *, struct nl_parser_param *), + struct nl_object **result, + int *syserror) { struct nl_cb *cb; int err; struct pickup_param pp = { - .parser = parser, + .parser = parser, }; cb = nl_cb_clone(sk->s_cb); @@ -1129,6 +1155,11 @@ int nl_pickup(struct nl_sock *sk, return -NLE_NOMEM; nl_cb_set(cb, NL_CB_VALID, NL_CB_CUSTOM, __pickup_answer, &pp); + if (syserror) { + *syserror = 0; + pp.syserror = syserror; + nl_cb_err(cb, NL_CB_CUSTOM, __pickup_answer_syserr, &pp); + } err = nl_recvmsgs(sk, cb); if (err < 0) diff --git a/lib/route/link.c b/lib/route/link.c index 7a53532..0b3238f 100644 --- a/lib/route/link.c +++ b/lib/route/link.c @@ -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; diff --git a/lib/utils.c b/lib/utils.c index 67612bd..795eeb7 100644 --- a/lib/utils.c +++ b/lib/utils.c @@ -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),