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 #if IFLA_INFO_MAX < 5
  31 #define IFLA_INFO_SLAVE_KIND 4
  32 #endif
  33
  34 static struct nln *nln = NULL;
  35 static struct rtnetlink_change rtn_change;
  36
  37 /* Returns true if the given netlink msg type corresponds to RTNLGRP_LINK. */
  38 bool
  39 rtnetlink_type_is_rtnlgrp_link(uint16_t type)
  40 {
  41     return type == RTM_NEWLINK || type == RTM_DELLINK;
  42 }
  43
  44 /* Returns true if the given netlink msg type corresponds to
  45  * RTNLGRP_IPV4_IFADDR or RTNLGRP_IPV6_IFADDR. */
  46 bool
  47 rtnetlink_type_is_rtnlgrp_addr(uint16_t type)
  48 {
  49     return type == RTM_NEWADDR || type == RTM_DELADDR;
  50 }
  51
  52 /* Parses nested nlattr for link info. Returns false if unparseable, else
  53  * populates 'change' and returns true. */
  54 static bool
  55 rtnetlink_parse_link_info(const struct nlattr *nla,
  56                           struct rtnetlink_change *change)
  57 {
  58     bool parsed = false;
  59
  60     static const struct nl_policy linkinfo_policy[] = {
  61         [IFLA_INFO_KIND] = { .type = NL_A_STRING, .optional = true  },
  62         [IFLA_INFO_SLAVE_KIND] = { .type = NL_A_STRING, .optional = true  },
  63     };
  64
  65     struct nlattr *linkinfo[ARRAY_SIZE(linkinfo_policy)];
  66
  67     parsed = nl_parse_nested(nla, linkinfo_policy, linkinfo,
  68                              ARRAY_SIZE(linkinfo_policy));
  69
  70     if (parsed) {
  71         change->primary = (linkinfo[IFLA_INFO_KIND]
  72                            ? nl_attr_get_string(linkinfo[IFLA_INFO_KIND])
  73                            : NULL);
  74         change->sub = (linkinfo[IFLA_INFO_SLAVE_KIND]
  75                        ? nl_attr_get_string(linkinfo[IFLA_INFO_SLAVE_KIND])
  76                        : NULL);
  77     }
  78
  79     return parsed;
  80 }
  81
  82 /* Parses a rtnetlink message 'buf' into 'change'.  If 'buf' is unparseable,
  83  * leaves 'change' untouched and returns false.  Otherwise, populates 'change'
  84  * and returns true. */
  85 bool
  86 rtnetlink_parse(struct ofpbuf *buf, struct rtnetlink_change *change)
  87 {
  88     const struct nlmsghdr *nlmsg = buf->data;
  89     bool parsed = false;
  90
  91     if (rtnetlink_type_is_rtnlgrp_link(nlmsg->nlmsg_type)) {
  92         /* Policy for RTNLGRP_LINK messages.
  93          *
  94          * There are *many* more fields in these messages, but currently we
  95          * only care about these fields. */
  96         static const struct nl_policy policy[] = {
  97             [IFLA_IFNAME] = { .type = NL_A_STRING, .optional = false },
  98             [IFLA_MASTER] = { .type = NL_A_U32,    .optional = true },
  99             [IFLA_MTU]    = { .type = NL_A_U32,    .optional = true },
 100             [IFLA_ADDRESS] = { .type = NL_A_UNSPEC, .optional = true },
 101             [IFLA_LINKINFO] = { .type = NL_A_NESTED, .optional = true },
 102         };
 103
 104         struct nlattr *attrs[ARRAY_SIZE(policy)];
 105
 106         parsed = nl_policy_parse(buf, NLMSG_HDRLEN + sizeof(struct ifinfomsg),
 107                                  policy, attrs, ARRAY_SIZE(policy));
 108
 109         if (parsed) {
 110             const struct ifinfomsg *ifinfo;
 111
 112             ifinfo = ofpbuf_at(buf, NLMSG_HDRLEN, sizeof *ifinfo);
 113
 114             change->nlmsg_type     = nlmsg->nlmsg_type;
 115             change->if_index       = ifinfo->ifi_index;
 116             change->ifname         = nl_attr_get_string(attrs[IFLA_IFNAME]);
 117             change->ifi_flags      = ifinfo->ifi_flags;
 118             change->master_ifindex = (attrs[IFLA_MASTER]
 119                                       ? nl_attr_get_u32(attrs[IFLA_MASTER])
 120                                       : 0);
 121             change->mtu            = (attrs[IFLA_MTU]
 122                                       ? nl_attr_get_u32(attrs[IFLA_MTU])
 123                                       : 0);
 124
 125             if (attrs[IFLA_ADDRESS] &&
 126                 nl_attr_get_size(attrs[IFLA_ADDRESS]) == ETH_ADDR_LEN) {
 127                 memcpy(&change->mac, nl_attr_get(attrs[IFLA_ADDRESS]),
 128                        ETH_ADDR_LEN);
 129             } else {
 130                 memset(&change->mac, 0, ETH_ADDR_LEN);
 131             }
 132
 133             if (attrs[IFLA_LINKINFO]) {
 134                 parsed = rtnetlink_parse_link_info(attrs[IFLA_LINKINFO],
 135                                                    change);
 136             } else {
 137                 change->primary = NULL;
 138                 change->sub = NULL;
 139             }
 140         }
 141     } else if (rtnetlink_type_is_rtnlgrp_addr(nlmsg->nlmsg_type)) {
 142         /* Policy for RTNLGRP_IPV4_IFADDR/RTNLGRP_IPV6_IFADDR messages.
 143          *
 144          * There are *many* more fields in these messages, but currently we
 145          * only care about these fields. */
 146         static const struct nl_policy policy[] = {
 147             [IFA_LABEL] = { .type = NL_A_STRING, .optional = true },
 148         };
 149
 150         struct nlattr *attrs[ARRAY_SIZE(policy)];
 151
 152         parsed = nl_policy_parse(buf, NLMSG_HDRLEN + sizeof(struct ifaddrmsg),
 153                                  policy, attrs, ARRAY_SIZE(policy));
 154
 155         if (parsed) {
 156             const struct ifaddrmsg *ifaddr;
 157
 158             ifaddr = ofpbuf_at(buf, NLMSG_HDRLEN, sizeof *ifaddr);
 159
 160             change->nlmsg_type     = nlmsg->nlmsg_type;
 161             change->if_index       = ifaddr->ifa_index;
 162             change->ifname         = (attrs[IFA_LABEL]
 163                                       ? nl_attr_get_string(attrs[IFA_LABEL])
 164                                       : NULL);
 165         }
 166     }
 167
 168     return parsed;
 169 }
 170
 171 /* Return RTNLGRP_LINK on success, 0 on parse error. */
 172 static int
 173 rtnetlink_parse_cb(struct ofpbuf *buf, void *change)
 174 {
 175     return rtnetlink_parse(buf, change) ? RTNLGRP_LINK : 0;
 176 }
 177
 178 /* Registers 'cb' to be called with auxiliary data 'aux' with network device
 179  * change notifications.  The notifier is stored in 'notifier', which the
 180  * caller must not modify or free.
 181  *
 182  * This is probably not the function that you want.  You should probably be
 183  * using dpif_port_poll() or netdev_change_seq(), which unlike this function
 184  * are not Linux-specific.
 185  *
 186  * xxx Joins more multicast groups when needed.
 187  *
 188  * Returns an initialized nln_notifier if successful, NULL otherwise. */
 189 struct nln_notifier *
 190 rtnetlink_notifier_create(rtnetlink_notify_func *cb, void *aux)
 191 {
 192     if (!nln) {
 193         nln = nln_create(NETLINK_ROUTE, rtnetlink_parse_cb, &rtn_change);
 194     }
 195
 196     return nln_notifier_create(nln, RTNLGRP_LINK, (nln_notify_func *) cb, aux);
 197 }
 198
 199 /* Destroys 'notifier', which must have previously been created with
 200  * rtnetlink_notifier_register(). */
 201 void
 202 rtnetlink_notifier_destroy(struct nln_notifier *notifier)
 203 {
 204     nln_notifier_destroy(notifier);
 205 }
 206
 207 /* Calls all of the registered notifiers, passing along any as-yet-unreported
 208  * netdev change events. */
 209 void
 210 rtnetlink_run(void)
 211 {
 212     if (nln) {
 213         nln_run(nln);
 214     }
 215 }
 216
 217 /* Causes poll_block() to wake up when network device change notifications are
 218  * ready. */
 219 void
 220 rtnetlink_wait(void)
 221 {
 222     if (nln) {
 223         nln_wait(nln);
 224     }
 225 }
 226
 227 /* Report RTNLGRP_LINK netdev change events. */
 228 void
 229 rtnetlink_report_link(void)
 230 {
 231     if (nln) {
 232         nln_report(nln, NULL, RTNLGRP_LINK);
 233     }
 234 }