lib/rtnetlink.c

   1 /*
   2  * Copyright (c) 2009, 2010, 2013, 2015, 2016 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.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 "openvswitch/ofpbuf.h"
  28 #include "packets.h"
  29
  30 static struct nln *nln = NULL;
  31 static struct rtnetlink_change rtn_change;
  32
  33 /* Returns true if the given netlink msg type corresponds to RTNLGRP_LINK. */
  34 bool
  35 rtnetlink_type_is_rtnlgrp_link(uint16_t type)
  36 {
  37     return type == RTM_NEWLINK || type == RTM_DELLINK;
  38 }
  39
  40 /* Returns true if the given netlink msg type corresponds to
  41  * RTNLGRP_IPV4_IFADDR or RTNLGRP_IPV6_IFADDR. */
  42 bool
  43 rtnetlink_type_is_rtnlgrp_addr(uint16_t type)
  44 {
  45     return type == RTM_NEWADDR || type == RTM_DELADDR;
  46 }
  47
  48 /* Parses a rtnetlink message 'buf' into 'change'.  If 'buf' is unparseable,
  49  * leaves 'change' untouched and returns false.  Otherwise, populates 'change'
  50  * and returns true. */
  51 bool
  52 rtnetlink_parse(struct ofpbuf *buf, struct rtnetlink_change *change)
  53 {
  54     const struct nlmsghdr *nlmsg = buf->data;
  55     bool parsed = false;
  56
  57     if (rtnetlink_type_is_rtnlgrp_link(nlmsg->nlmsg_type)) {
  58         /* Policy for RTNLGRP_LINK messages.
  59          *
  60          * There are *many* more fields in these messages, but currently we
  61          * only care about these fields. */
  62         static const struct nl_policy policy[] = {
  63             [IFLA_IFNAME] = { .type = NL_A_STRING, .optional = false },
  64             [IFLA_MASTER] = { .type = NL_A_U32,    .optional = true },
  65             [IFLA_MTU]    = { .type = NL_A_U32,    .optional = true },
  66             [IFLA_ADDRESS] = { .type = NL_A_UNSPEC, .optional = true },
  67         };
  68
  69         struct nlattr *attrs[ARRAY_SIZE(policy)];
  70
  71         parsed = nl_policy_parse(buf, NLMSG_HDRLEN + sizeof(struct ifinfomsg),
  72                                  policy, attrs, ARRAY_SIZE(policy));
  73
  74         if (parsed) {
  75             const struct ifinfomsg *ifinfo;
  76
  77             ifinfo = ofpbuf_at(buf, NLMSG_HDRLEN, sizeof *ifinfo);
  78
  79             change->nlmsg_type     = nlmsg->nlmsg_type;
  80             change->if_index       = ifinfo->ifi_index;
  81             change->ifname         = nl_attr_get_string(attrs[IFLA_IFNAME]);
  82             change->ifi_flags      = ifinfo->ifi_flags;
  83             change->master_ifindex = (attrs[IFLA_MASTER]
  84                                       ? nl_attr_get_u32(attrs[IFLA_MASTER])
  85                                       : 0);
  86             change->mtu            = (attrs[IFLA_MTU]
  87                                       ? nl_attr_get_u32(attrs[IFLA_MTU])
  88                                       : 0);
  89
  90             if (attrs[IFLA_ADDRESS] &&
  91                 nl_attr_get_size(attrs[IFLA_ADDRESS]) == ETH_ADDR_LEN) {
  92                 memcpy(&change->mac, nl_attr_get(attrs[IFLA_ADDRESS]),
  93                        ETH_ADDR_LEN);
  94             } else {
  95                 memset(&change->mac, 0, ETH_ADDR_LEN);
  96             }
  97         }
  98     } else if (rtnetlink_type_is_rtnlgrp_addr(nlmsg->nlmsg_type)) {
  99         /* Policy for RTNLGRP_IPV4_IFADDR/RTNLGRP_IPV6_IFADDR messages.
 100          *
 101          * There are *many* more fields in these messages, but currently we
 102          * only care about these fields. */
 103         static const struct nl_policy policy[] = {
 104             [IFA_LABEL] = { .type = NL_A_STRING, .optional = true },
 105         };
 106
 107         struct nlattr *attrs[ARRAY_SIZE(policy)];
 108
 109         parsed = nl_policy_parse(buf, NLMSG_HDRLEN + sizeof(struct ifaddrmsg),
 110                                  policy, attrs, ARRAY_SIZE(policy));
 111
 112         if (parsed) {
 113             const struct ifaddrmsg *ifaddr;
 114
 115             ifaddr = ofpbuf_at(buf, NLMSG_HDRLEN, sizeof *ifaddr);
 116
 117             change->nlmsg_type     = nlmsg->nlmsg_type;
 118             change->if_index       = ifaddr->ifa_index;
 119             change->ifname         = (attrs[IFA_LABEL]
 120                                       ? nl_attr_get_string(attrs[IFA_LABEL])
 121                                       : NULL);
 122         }
 123     }
 124
 125     return parsed;
 126 }
 127
 128 /* Return RTNLGRP_LINK on success, 0 on parse error. */
 129 static int
 130 rtnetlink_parse_cb(struct ofpbuf *buf, void *change)
 131 {
 132     return rtnetlink_parse(buf, change) ? RTNLGRP_LINK : 0;
 133 }
 134
 135 /* Registers 'cb' to be called with auxiliary data 'aux' with network device
 136  * change notifications.  The notifier is stored in 'notifier', which the
 137  * caller must not modify or free.
 138  *
 139  * This is probably not the function that you want.  You should probably be
 140  * using dpif_port_poll() or netdev_change_seq(), which unlike this function
 141  * are not Linux-specific.
 142  *
 143  * xxx Joins more multicast groups when needed.
 144  *
 145  * Returns an initialized nln_notifier if successful, NULL otherwise. */
 146 struct nln_notifier *
 147 rtnetlink_notifier_create(rtnetlink_notify_func *cb, void *aux)
 148 {
 149     if (!nln) {
 150         nln = nln_create(NETLINK_ROUTE, rtnetlink_parse_cb, &rtn_change);
 151     }
 152
 153     return nln_notifier_create(nln, RTNLGRP_LINK, (nln_notify_func *) cb, aux);
 154 }
 155
 156 /* Destroys 'notifier', which must have previously been created with
 157  * rtnetlink_notifier_register(). */
 158 void
 159 rtnetlink_notifier_destroy(struct nln_notifier *notifier)
 160 {
 161     nln_notifier_destroy(notifier);
 162 }
 163
 164 /* Calls all of the registered notifiers, passing along any as-yet-unreported
 165  * netdev change events. */
 166 void
 167 rtnetlink_run(void)
 168 {
 169     if (nln) {
 170         nln_run(nln);
 171     }
 172 }
 173
 174 /* Causes poll_block() to wake up when network device change notifications are
 175  * ready. */
 176 void
 177 rtnetlink_wait(void)
 178 {
 179     if (nln) {
 180         nln_wait(nln);
 181     }
 182 }