Improve rtnl_link_change() behaviour
- avoid unncessary name change requests
The kernel does not check if the specified IFNAME is different
from the current name. It assumes that if IFNAME and ifindex
are both specified, a name change is requested. Therefore avoid
specyfing IFNAME if ifindex is provided and original and new
name are identical.
- move link building to own function (to allow link add later on)
- error if immutable changes have been made
- better documentation
This commit is contained in:
Thomas Graf
parent
b5918b5ce3
commit
96bc6d6f66
3 changed files with 132 additions and 75 deletions
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@ -48,8 +48,9 @@ extern "C" {
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#define NLE_PKTLOC_FILE 29
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#define NLE_PARSE_ERR 30
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#define NLE_NODEV 31
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#define NLE_IMMUTABLE 32
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#define NLE_MAX NLE_NODEV
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#define NLE_MAX NLE_IMMUTABLE
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extern const char * nl_geterror(int);
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extern void nl_perror(int, const char *);
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@ -45,6 +45,7 @@ static const char *errmsg[NLE_MAX+1] = {
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[NLE_PKTLOC_FILE] = "Unable to open packet location file",
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[NLE_PARSE_ERR] = "Unable to parse object",
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[NLE_NODEV] = "No such device",
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[NLE_IMMUTABLE] = "Immutable attribute",
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};
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/**
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203
lib/route/link.c
203
lib/route/link.c
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@ -1031,85 +1031,56 @@ struct rtnl_link *rtnl_link_get_by_name(struct nl_cache *cache,
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* @{
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*/
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/**
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* Builds a netlink change request message to change link attributes
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* @arg old link to be changed
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* @arg tmpl template with requested changes
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* @arg flags additional netlink message flags
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* @arg result Result pointer
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*
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* Builds a new netlink message requesting a change of link attributes.
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* The netlink message header isn't fully equipped with all relevant
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* fields and must be sent out via nl_send_auto_complete() or
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* supplemented as needed.
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* \a old must point to a link currently configured in the kernel
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* and \a tmpl must contain the attributes to be changed set via
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* \c rtnl_link_set_* functions.
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*
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* @return 0 on success or a negative error code.
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* @note Not all attributes can be changed, see
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* \ref link_changeable "Changeable Attributes" for more details.
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*/
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int rtnl_link_build_change_request(struct rtnl_link *old,
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struct rtnl_link *tmpl, int flags,
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struct nl_msg **result)
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static int build_link_msg(int cmd, struct ifinfomsg *hdr,
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struct rtnl_link *link, int flags, struct nl_msg **result)
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{
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struct nl_msg *msg;
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struct nlattr *af_spec;
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struct ifinfomsg ifi = {
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.ifi_family = old->l_family,
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.ifi_index = old->l_index,
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};
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if (tmpl->ce_mask & LINK_ATTR_FLAGS) {
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ifi.ifi_flags = old->l_flags & ~tmpl->l_flag_mask;
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ifi.ifi_flags |= tmpl->l_flags;
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}
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msg = nlmsg_alloc_simple(RTM_SETLINK, flags);
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msg = nlmsg_alloc_simple(cmd, flags);
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if (!msg)
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return -NLE_NOMEM;
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if (nlmsg_append(msg, &ifi, sizeof(ifi), NLMSG_ALIGNTO) < 0)
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if (nlmsg_append(msg, hdr, sizeof(*hdr), NLMSG_ALIGNTO) < 0)
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goto nla_put_failure;
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if (tmpl->ce_mask & LINK_ATTR_ADDR)
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NLA_PUT_ADDR(msg, IFLA_ADDRESS, tmpl->l_addr);
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if (link->ce_mask & LINK_ATTR_ADDR)
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NLA_PUT_ADDR(msg, IFLA_ADDRESS, link->l_addr);
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if (tmpl->ce_mask & LINK_ATTR_BRD)
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NLA_PUT_ADDR(msg, IFLA_BROADCAST, tmpl->l_bcast);
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if (link->ce_mask & LINK_ATTR_BRD)
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NLA_PUT_ADDR(msg, IFLA_BROADCAST, link->l_bcast);
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if (tmpl->ce_mask & LINK_ATTR_MTU)
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NLA_PUT_U32(msg, IFLA_MTU, tmpl->l_mtu);
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if (link->ce_mask & LINK_ATTR_MTU)
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NLA_PUT_U32(msg, IFLA_MTU, link->l_mtu);
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if (tmpl->ce_mask & LINK_ATTR_TXQLEN)
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NLA_PUT_U32(msg, IFLA_TXQLEN, tmpl->l_txqlen);
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if (link->ce_mask & LINK_ATTR_TXQLEN)
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NLA_PUT_U32(msg, IFLA_TXQLEN, link->l_txqlen);
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if (tmpl->ce_mask & LINK_ATTR_WEIGHT)
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NLA_PUT_U32(msg, IFLA_WEIGHT, tmpl->l_weight);
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if (link->ce_mask & LINK_ATTR_WEIGHT)
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NLA_PUT_U32(msg, IFLA_WEIGHT, link->l_weight);
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if (tmpl->ce_mask & LINK_ATTR_IFNAME)
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NLA_PUT_STRING(msg, IFLA_IFNAME, tmpl->l_name);
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if (link->ce_mask & LINK_ATTR_IFNAME)
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NLA_PUT_STRING(msg, IFLA_IFNAME, link->l_name);
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if (tmpl->ce_mask & LINK_ATTR_OPERSTATE)
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NLA_PUT_U8(msg, IFLA_OPERSTATE, tmpl->l_operstate);
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if (link->ce_mask & LINK_ATTR_OPERSTATE)
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NLA_PUT_U8(msg, IFLA_OPERSTATE, link->l_operstate);
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if (tmpl->ce_mask & LINK_ATTR_LINKMODE)
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NLA_PUT_U8(msg, IFLA_LINKMODE, tmpl->l_linkmode);
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if (link->ce_mask & LINK_ATTR_LINKMODE)
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NLA_PUT_U8(msg, IFLA_LINKMODE, link->l_linkmode);
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if (tmpl->ce_mask & LINK_ATTR_IFALIAS)
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NLA_PUT_STRING(msg, IFLA_IFALIAS, tmpl->l_ifalias);
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if (link->ce_mask & LINK_ATTR_IFALIAS)
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NLA_PUT_STRING(msg, IFLA_IFALIAS, link->l_ifalias);
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if ((tmpl->ce_mask & LINK_ATTR_LINKINFO) && tmpl->l_info_ops &&
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tmpl->l_info_ops->io_put_attrs) {
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if ((link->ce_mask & LINK_ATTR_LINKINFO) && link->l_info_ops &&
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link->l_info_ops->io_put_attrs) {
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struct nlattr *info;
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if (!(info = nla_nest_start(msg, IFLA_LINKINFO)))
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goto nla_put_failure;
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NLA_PUT_STRING(msg, IFLA_INFO_KIND, tmpl->l_info_ops->io_name);
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NLA_PUT_STRING(msg, IFLA_INFO_KIND, link->l_info_ops->io_name);
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if (tmpl->l_info_ops->io_put_attrs(msg, tmpl) < 0)
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if (link->l_info_ops->io_put_attrs(msg, link) < 0)
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goto nla_put_failure;
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nla_nest_end(msg, info);
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@ -1118,7 +1089,7 @@ int rtnl_link_build_change_request(struct rtnl_link *old,
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if (!(af_spec = nla_nest_start(msg, IFLA_AF_SPEC)))
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goto nla_put_failure;
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if (do_foreach_af(tmpl, af_fill, msg) < 0)
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if (do_foreach_af(link, af_fill, msg) < 0)
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goto nla_put_failure;
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nla_nest_end(msg, af_spec);
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@ -1132,35 +1103,119 @@ nla_put_failure:
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}
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/**
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* Change link attributes
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* @arg sk Netlink socket.
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* @arg old link to be changed
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* @arg tmpl template with requested changes
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* Build a netlink message requesting the modification of a link
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* @arg orig original link to change
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* @arg changes link containing the changes to be made
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* @arg flags additional netlink message flags
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* @arg result pointer to store resulting netlink message
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*
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* The behaviour of this function is identical to rtnl_link_change() with
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* the exception that it will not send the message but return it in the
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* provided return pointer instead.
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*
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* @see rtnl_link_change()
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*
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* @note The resulting message will have message type set to RTM_NEWLINK
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* which may not work with older kernels. You may have to modify it
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* to RTM_SETLINK (does not allow changing link info attributes) to
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* have the change request work with older kernels.
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*
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* @return 0 on success or a negative error code.
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*/
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int rtnl_link_build_change_request(struct rtnl_link *orig,
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struct rtnl_link *changes, int flags,
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struct nl_msg **result)
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{
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struct ifinfomsg ifi = {
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.ifi_family = orig->l_family,
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.ifi_index = orig->l_index,
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};
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int err;
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if (changes->ce_mask & LINK_ATTR_FLAGS) {
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ifi.ifi_flags = orig->l_flags & ~changes->l_flag_mask;
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ifi.ifi_flags |= changes->l_flags;
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}
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if (changes->l_family && changes->l_family != orig->l_family) {
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APPBUG("link change: family is immutable");
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return -NLE_IMMUTABLE;
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}
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/* Avoid unnecessary name change requests */
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if (orig->ce_mask & LINK_ATTR_IFINDEX &&
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orig->ce_mask & LINK_ATTR_IFNAME &&
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changes->ce_mask & LINK_ATTR_IFNAME &&
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!strcmp(orig->l_name, changes->l_name))
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changes->ce_mask &= ~LINK_ATTR_IFNAME;
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if ((err = build_link_msg(RTM_NEWLINK, &ifi, changes, flags, result)) < 0)
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goto errout;
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return 0;
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errout:
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return err;
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}
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/**
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* Change link
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* @arg sk netlink socket.
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* @arg orig original link to be changed
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* @arg changes link containing the changes to be made
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* @arg flags additional netlink message flags
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*
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* Builds a new netlink message by calling rtnl_link_build_change_request(),
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* sends the request to the kernel and waits for the next ACK to be
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* received, i.e. blocks until the request has been processed.
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* Builds a \c RTM_NEWLINK netlink message requesting the change of
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* a network link. If -EOPNOTSUPP is returned by the kernel, the
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* message type will be changed to \c RTM_SETLINK and the message is
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* resent to work around older kernel versions.
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*
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* @return 0 on success or a negative error code
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* @note Not all attributes can be changed, see
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* \ref link_changeable "Changeable Attributes" for more details.
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* The link to be changed is looked up based on the interface index
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* supplied in the \p orig link. Optionaly the link name is used but
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* only if no interface index is provided, otherwise providing an
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* link name will result in the link name being changed.
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*
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* If no matching link exists, the function will return
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* -NLE_OBJ_NOTFOUND.
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*
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* After sending, the function will wait for the ACK or an eventual
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* error message to be received and will therefore block until the
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* operation has been completed.
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*
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* @note Disabling auto-ack (nl_socket_disable_auto_ack()) will cause
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* this function to return immediately after sending. In this case,
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* it is the responsibility of the caller to handle any error
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* messages returned.
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*
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* @note The link name can only be changed if the link has been put
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* in opertional down state. (~IF_UP)
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*
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* @return 0 on success or a negative error code.
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*/
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int rtnl_link_change(struct nl_sock *sk, struct rtnl_link *old,
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struct rtnl_link *tmpl, int flags)
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int rtnl_link_change(struct nl_sock *sk, struct rtnl_link *orig,
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struct rtnl_link *changes, int flags)
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{
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struct nl_msg *msg;
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int err;
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if ((err = rtnl_link_build_change_request(old, tmpl, flags, &msg)) < 0)
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return err;
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err = nl_send_auto_complete(sk, msg);
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nlmsg_free(msg);
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err = rtnl_link_build_change_request(orig, changes, flags, &msg);
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if (err < 0)
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return err;
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return wait_for_ack(sk);
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retry:
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err = nl_send_auto_complete(sk, msg);
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if (err < 0)
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goto errout;
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err = wait_for_ack(sk);
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if (err == -NLE_OPNOTSUPP && msg->nm_nlh->nlmsg_type == RTM_NEWLINK) {
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msg->nm_nlh->nlmsg_type = RTM_SETLINK;
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goto retry;
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}
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errout:
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nlmsg_free(msg);
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return err;
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}
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/**
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