lib/rtnetlink-link.c

   1 /*
   2  * Copyright (c) 2009, 2010, 2013 Nicira, Inc.
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at:
   7  *
   8  *     http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16
  17 #include <config.h>
  18
  19 #include "rtnetlink-link.h"
  20
  21 #include <sys/socket.h>
  22 #include <linux/rtnetlink.h>
  23 #include <net/if.h>
  24
  25 #include "netlink.h"
  26 #include "netlink-notifier.h"
  27 #include "ofpbuf.h"
  28
  29 static struct nln *nln = NULL;
  30 static struct rtnetlink_link_change rtn_change;
  31
  32 /* Parses a rtnetlink message 'buf' into 'change'.  If 'buf' is unparseable,
  33  * leaves 'change' untouched and returns false.  Otherwise, populates 'change'
  34  * and returns true. */
  35 bool
  36 rtnetlink_link_parse(struct ofpbuf *buf,
  37                      struct rtnetlink_link_change *change)
  38 {
  39     bool parsed;
  40
  41     /* Policy for RTNLGRP_LINK messages.
  42      *
  43      * There are *many* more fields in these messages, but currently we
  44      * only care about these fields. */
  45     static const struct nl_policy policy[] = {
  46         [IFLA_IFNAME] = { .type = NL_A_STRING, .optional = false },
  47         [IFLA_MASTER] = { .type = NL_A_U32,    .optional = true },
  48         [IFLA_MTU]    = { .type = NL_A_U32,    .optional = true },
  49         [IFLA_ADDRESS] = { .type = NL_A_UNSPEC, .optional = true },
  50     };
  51
  52     struct nlattr *attrs[ARRAY_SIZE(policy)];
  53
  54     parsed = nl_policy_parse(buf, NLMSG_HDRLEN + sizeof(struct ifinfomsg),
  55                              policy, attrs, ARRAY_SIZE(policy));
  56
  57     if (parsed) {
  58         const struct nlmsghdr *nlmsg;
  59         const struct ifinfomsg *ifinfo;
  60
  61         nlmsg  = ofpbuf_data(buf);
  62         ifinfo = ofpbuf_at(buf, NLMSG_HDRLEN, sizeof *ifinfo);
  63
  64         change->nlmsg_type     = nlmsg->nlmsg_type;
  65         change->ifi_index      = ifinfo->ifi_index;
  66         change->ifname         = nl_attr_get_string(attrs[IFLA_IFNAME]);
  67         change->ifi_flags      = ifinfo->ifi_flags;
  68         change->master_ifindex = (attrs[IFLA_MASTER]
  69                                   ? nl_attr_get_u32(attrs[IFLA_MASTER])
  70                                   : 0);
  71         change->mtu            = (attrs[IFLA_MTU]
  72                                   ? nl_attr_get_u32(attrs[IFLA_MTU])
  73                                   : 0);
  74
  75         if (attrs[IFLA_ADDRESS] &&
  76             nl_attr_get_size(attrs[IFLA_ADDRESS]) == ETH_ALEN) {
  77             memcpy(change->addr, nl_attr_get(attrs[IFLA_ADDRESS]), ETH_ALEN);
  78         } else {
  79             memset(change->addr, 0, ETH_ALEN);
  80         }
  81     }
  82
  83     return parsed;
  84 }
  85
  86 static bool
  87 rtnetlink_link_parse_cb(struct ofpbuf *buf, void *change)
  88 {
  89     return rtnetlink_link_parse(buf, change);
  90 }
  91
  92 /* Registers 'cb' to be called with auxiliary data 'aux' with network device
  93  * change notifications.  The notifier is stored in 'notifier', which the
  94  * caller must not modify or free.
  95  *
  96  * This is probably not the function that you want.  You should probably be
  97  * using dpif_port_poll() or netdev_change_seq(), which unlike this function
  98  * are not Linux-specific.
  99  *
 100  * Returns an initialized nln_notifier if successful, NULL otherwise. */
 101 struct nln_notifier *
 102 rtnetlink_link_notifier_create(rtnetlink_link_notify_func *cb, void *aux)
 103 {
 104     if (!nln) {
 105         nln = nln_create(NETLINK_ROUTE, RTNLGRP_LINK, rtnetlink_link_parse_cb,
 106                          &rtn_change);
 107     }
 108
 109     return nln_notifier_create(nln, (nln_notify_func *) cb, aux);
 110 }
 111
 112 /* Destroys 'notifier', which must have previously been created with
 113  * rtnetlink_link_notifier_register(). */
 114 void
 115 rtnetlink_link_notifier_destroy(struct nln_notifier *notifier)
 116 {
 117     nln_notifier_destroy(notifier);
 118 }
 119
 120 /* Calls all of the registered notifiers, passing along any as-yet-unreported
 121  * netdev change events. */
 122 void
 123 rtnetlink_link_run(void)
 124 {
 125     if (nln) {
 126         nln_run(nln);
 127     }
 128 }
 129
 130 /* Causes poll_block() to wake up when network device change notifications are
 131  * ready. */
 132 void
 133 rtnetlink_link_wait(void)
 134 {
 135     if (nln) {
 136         nln_wait(nln);
 137     }
 138 }