src/networkd/link.c

   1 /*#############################################################################
   2 #                                                                             #
   3 # IPFire.org - A linux based firewall                                         #
   4 # Copyright (C) 2023 IPFire Network Development Team                          #
   5 #                                                                             #
   6 # This program is free software: you can redistribute it and/or modify        #
   7 # it under the terms of the GNU General Public License as published by        #
   8 # the Free Software Foundation, either version 3 of the License, or           #
   9 # (at your option) any later version.                                         #
  10 #                                                                             #
  11 # This program is distributed in the hope that it will be useful,             #
  12 # but WITHOUT ANY WARRANTY; without even the implied warranty of              #
  13 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the               #
  14 # GNU General Public License for more details.                                #
  15 #                                                                             #
  16 # You should have received a copy of the GNU General Public License           #
  17 # along with this program.  If not, see <http://www.gnu.org/licenses/>.       #
  18 #                                                                             #
  19 #############################################################################*/
  20
  21 #include <net/if.h>
  22 #include <stddef.h>
  23 #include <stdlib.h>
  24 #include <string.h>
  25
  26 #include <systemd/sd-netlink.h>
  27
  28 #include "daemon.h"
  29 #include "link.h"
  30 #include "links.h"
  31 #include "logging.h"
  32 #include "string.h"
  33
  34 struct nw_link {
  35         nw_daemon* daemon;
  36         int nrefs;
  37
  38         // Interface Index
  39         int ifindex;
  40
  41         // Interface Name
  42         char ifname[IF_NAMESIZE];
  43
  44         // MTU
  45         uint32_t mtu;
  46         uint32_t min_mtu;
  47         uint32_t max_mtu;
  48 };
  49
  50 int nw_link_create(nw_link** link, nw_daemon* daemon, int ifindex) {
  51         // Allocate a new object
  52         nw_link* l = calloc(1, sizeof(*l));
  53         if (!l)
  54                 return 1;
  55
  56         // Store a reference to the daemon
  57         l->daemon = nw_daemon_ref(daemon);
  58
  59         // Initialize the reference counter
  60         l->nrefs = 1;
  61
  62         // Store the ifindex
  63         l->ifindex = ifindex;
  64
  65         DEBUG("New link allocated (ifindex = %d)\n", l->ifindex);
  66
  67         *link = l;
  68
  69         return 0;
  70 }
  71
  72 static void nw_link_free(nw_link* link) {
  73         DEBUG("Freeing link (ifindex = %d)\n", link->ifindex);
  74
  75         if (link->daemon)
  76                 nw_daemon_unref(link->daemon);
  77 }
  78
  79 nw_link* nw_link_ref(nw_link* link) {
  80         link->nrefs++;
  81
  82         return link;
  83 }
  84
  85 nw_link* nw_link_unref(nw_link* link) {
  86         if (--link->nrefs > 0)
  87                 return link;
  88
  89         nw_link_free(link);
  90         return NULL;
  91 }
  92
  93 int nw_link_ifindex(nw_link* link) {
  94         return link->ifindex;
  95 }
  96
  97 static int nw_link_update_ifname(nw_link* link, sd_netlink_message* message) {
  98         const char* ifname = NULL;
  99         int r;
 100
 101         r = sd_netlink_message_read_string(message, IFLA_IFNAME, &ifname);
 102         if (r < 0) {
 103                 ERROR("Could not read link name for link %d: %m\n", link->ifindex);
 104                 return 1;
 105         }
 106
 107         // Do nothing if the name is already set
 108         if (strcmp(link->ifname, ifname) == 0)
 109                 return 0;
 110
 111         // Otherwise update the name
 112         r = nw_string_set(link->ifname, ifname);
 113         if (r) {
 114                 ERROR("Could not set link name: %m\n");
 115                 return 1;
 116         }
 117
 118         DEBUG("Link %d has been renamed to '%s'\n", link->ifindex, link->ifname);
 119
 120         return 0;
 121 }
 122
 123 static int nw_link_update_mtu(nw_link* link, sd_netlink_message* message) {
 124         uint32_t mtu = 0;
 125         uint32_t min_mtu = 0;
 126         uint32_t max_mtu = 0;
 127         int r;
 128
 129         // Read the MTU
 130         r = sd_netlink_message_read_u32(message, IFLA_MTU, &mtu);
 131         if (r < 0) {
 132                 ERROR("Could not read MTU for link %d: %m\n", link->ifindex);
 133                 return r;
 134         }
 135
 136         // Read the minimum MTU
 137         r = sd_netlink_message_read_u32(message, IFLA_MIN_MTU, &min_mtu);
 138         if (r < 0) {
 139                 ERROR("Could not read the minimum MTU for link %d: %m\n", link->ifindex);
 140                 return r;
 141         }
 142
 143         // Read the maximum MTU
 144         r = sd_netlink_message_read_u32(message, IFLA_MAX_MTU, &max_mtu);
 145         if (r < 0) {
 146                 ERROR("Could not read the maximum MTU for link %d: %m\n", link->ifindex);
 147                 return r;
 148         }
 149
 150         // Set the maximum MTU to infinity
 151         if (!max_mtu)
 152                 max_mtu = UINT32_MAX;
 153
 154         // Store min/max MTU
 155         link->min_mtu = min_mtu;
 156         link->max_mtu = max_mtu;
 157
 158         // End here, if the MTU has not been changed
 159         if (link->mtu == mtu)
 160                 return 0;
 161
 162         DEBUG("Link %d: MTU has changed to %" PRIu32 " (min: %" PRIu32 ", max: %" PRIu32 ")\n",
 163                 link->ifindex, link->mtu, link->min_mtu, link->max_mtu);
 164
 165         // Store MTU
 166         link->mtu = mtu;
 167
 168         return 0;
 169 }
 170
 171 /*
 172         This function is called whenever anything changes, so that we can
 173         update our internal link object.
 174 */
 175 static int nw_link_update(nw_link* link, sd_netlink_message* message) {
 176         int r;
 177
 178         // Update the interface name
 179         r = nw_link_update_ifname(link, message);
 180         if (r)
 181                 return r;
 182
 183         // Update the MTU
 184         r = nw_link_update_mtu(link, message);
 185         if (r)
 186                 return r;
 187
 188         return 0;
 189 }
 190
 191 int nw_link_process(sd_netlink* rtnl, sd_netlink_message* message, void* data) {
 192         nw_links* links = NULL;
 193         nw_link* link = NULL;
 194         const char* ifname = NULL;
 195         int ifindex;
 196         uint16_t type;
 197         int r;
 198
 199         nw_daemon* daemon = (nw_daemon*)data;
 200
 201         // Fetch links
 202         links = nw_daemon_links(daemon);
 203         if (!links) {
 204                 r = 1;
 205                 goto ERROR;
 206         }
 207
 208         // Check if this message could be received
 209         if (sd_netlink_message_is_error(message)) {
 210                 r = sd_netlink_message_get_errno(message);
 211                 if (r < 0)
 212                         ERROR("Could not receive link message: %m\n");
 213
 214                 goto IGNORE;
 215         }
 216
 217         // Fetch the message type
 218         r = sd_netlink_message_get_type(message, &type);
 219         if (r < 0) {
 220                 ERROR("Could not fetch message type: %m\n");
 221                 goto IGNORE;
 222         }
 223
 224         // Check type
 225         switch (type) {
 226                 case RTM_NEWLINK:
 227                 case RTM_DELLINK:
 228                         break;
 229
 230                 default:
 231                         ERROR("Received an unexpected message (type %u)\n", type);
 232                         goto IGNORE;
 233         }
 234
 235         // Fetch the interface index
 236         r = sd_rtnl_message_link_get_ifindex(message, &ifindex);
 237         if (r < 0) {
 238                 ERROR("Could not fetch ifindex: %m\n");
 239                 goto IGNORE;
 240         }
 241
 242         // Check interface index
 243         if (ifindex <= 0) {
 244                 ERROR("Received an invalid ifindex\n");
 245                 goto IGNORE;
 246         }
 247
 248         // Fetch the interface name
 249         r = sd_netlink_message_read_string(message, IFLA_IFNAME, &ifname);
 250         if (r < 0) {
 251                 ERROR("Received a netlink message without interface name: %m\n");
 252                 goto IGNORE;
 253         }
 254
 255         // Try finding an existing link
 256         link = nw_daemon_get_link_by_ifindex(daemon, ifindex);
 257
 258         switch (type) {
 259                 case RTM_NEWLINK:
 260                         // If the link doesn't exist, create it
 261                         if (!link) {
 262                                 r = nw_link_create(&link, daemon, ifindex);
 263                                 if (r) {
 264                                         ERROR("Could not create link: %m\n");
 265                                         goto ERROR;
 266                                 }
 267
 268                                 // Add it to the list
 269                                 r = nw_links_add_link(links, link);
 270                                 if (r)
 271                                         goto ERROR;
 272                         }
 273
 274                         // Import any data from the netlink message
 275                         r = nw_link_update(link, message);
 276                         if (r)
 277                                 goto ERROR;
 278
 279                         break;
 280
 281                 case RTM_DELLINK:
 282                         if (link)
 283                                 nw_links_drop_link(links, link);
 284
 285                         break;
 286         }
 287
 288 IGNORE:
 289         r = 0;
 290
 291 ERROR:
 292         if (links)
 293                 nw_links_unref(links);
 294         if (link)
 295                 nw_link_unref(link);
 296
 297         return r;
 298 }