src/net/ipv4.c

   1 #include <string.h>
   2 #include <stdint.h>
   3 #include <stdlib.h>
   4 #include <stdio.h>
   5 #include <errno.h>
   6 #include <byteswap.h>
   7 #include <gpxe/list.h>
   8 #include <gpxe/in.h>
   9 #include <gpxe/arp.h>
  10 #include <gpxe/if_ether.h>
  11 #include <gpxe/iobuf.h>
  12 #include <gpxe/netdevice.h>
  13 #include <gpxe/ip.h>
  14 #include <gpxe/tcpip.h>
  15 #include <gpxe/dhcp.h>
  16 #include <gpxe/settings.h>
  17
  18 /** @file
  19  *
  20  * IPv4 protocol
  21  *
  22  */
  23
  24 FILE_LICENCE ( GPL2_OR_LATER );
  25
  26 /* Unique IP datagram identification number */
  27 static uint16_t next_ident = 0;
  28
  29 struct net_protocol ipv4_protocol;
  30
  31 /** List of IPv4 miniroutes */
  32 struct list_head ipv4_miniroutes = LIST_HEAD_INIT ( ipv4_miniroutes );
  33
  34 /** List of fragment reassembly buffers */
  35 static LIST_HEAD ( frag_buffers );
  36
  37 /**
  38  * Add IPv4 minirouting table entry
  39  *
  40  * @v netdev            Network device
  41  * @v address           IPv4 address
  42  * @v netmask           Subnet mask
  43  * @v gateway           Gateway address (if any)
  44  * @ret miniroute       Routing table entry, or NULL
  45  */
  46 static struct ipv4_miniroute * __malloc
  47 add_ipv4_miniroute ( struct net_device *netdev, struct in_addr address,
  48                      struct in_addr netmask, struct in_addr gateway ) {
  49         struct ipv4_miniroute *miniroute;
  50
  51         DBG ( "IPv4 add %s", inet_ntoa ( address ) );
  52         DBG ( "/%s ", inet_ntoa ( netmask ) );
  53         if ( gateway.s_addr )
  54                 DBG ( "gw %s ", inet_ntoa ( gateway ) );
  55         DBG ( "via %s\n", netdev->name );
  56
  57         /* Allocate and populate miniroute structure */
  58         miniroute = malloc ( sizeof ( *miniroute ) );
  59         if ( ! miniroute ) {
  60                 DBG ( "IPv4 could not add miniroute\n" );
  61                 return NULL;
  62         }
  63
  64         /* Record routing information */
  65         miniroute->netdev = netdev_get ( netdev );
  66         miniroute->address = address;
  67         miniroute->netmask = netmask;
  68         miniroute->gateway = gateway;
  69
  70         /* Add to end of list if we have a gateway, otherwise
  71          * to start of list.
  72          */
  73         if ( gateway.s_addr ) {
  74                 list_add_tail ( &miniroute->list, &ipv4_miniroutes );
  75         } else {
  76                 list_add ( &miniroute->list, &ipv4_miniroutes );
  77         }
  78
  79         return miniroute;
  80 }
  81
  82 /**
  83  * Delete IPv4 minirouting table entry
  84  *
  85  * @v miniroute         Routing table entry
  86  */
  87 static void del_ipv4_miniroute ( struct ipv4_miniroute *miniroute ) {
  88
  89         DBG ( "IPv4 del %s", inet_ntoa ( miniroute->address ) );
  90         DBG ( "/%s ", inet_ntoa ( miniroute->netmask ) );
  91         if ( miniroute->gateway.s_addr )
  92                 DBG ( "gw %s ", inet_ntoa ( miniroute->gateway ) );
  93         DBG ( "via %s\n", miniroute->netdev->name );
  94
  95         netdev_put ( miniroute->netdev );
  96         list_del ( &miniroute->list );
  97         free ( miniroute );
  98 }
  99
 100 /**
 101  * Perform IPv4 routing
 102  *
 103  * @v dest              Final destination address
 104  * @ret dest            Next hop destination address
 105  * @ret miniroute       Routing table entry to use, or NULL if no route
 106  *
 107  * If the route requires use of a gateway, the next hop destination
 108  * address will be overwritten with the gateway address.
 109  */
 110 static struct ipv4_miniroute * ipv4_route ( struct in_addr *dest ) {
 111         struct ipv4_miniroute *miniroute;
 112         int local;
 113         int has_gw;
 114
 115         /* Never attempt to route the broadcast address */
 116         if ( dest->s_addr == INADDR_BROADCAST )
 117                 return NULL;
 118
 119         /* Find first usable route in routing table */
 120         list_for_each_entry ( miniroute, &ipv4_miniroutes, list ) {
 121                 if ( ! netdev_is_open ( miniroute->netdev ) )
 122                         continue;
 123                 local = ( ( ( dest->s_addr ^ miniroute->address.s_addr )
 124                             & miniroute->netmask.s_addr ) == 0 );
 125                 has_gw = ( miniroute->gateway.s_addr );
 126                 if ( local || has_gw ) {
 127                         if ( ! local )
 128                                 *dest = miniroute->gateway;
 129                         return miniroute;
 130                 }
 131         }
 132
 133         return NULL;
 134 }
 135
 136 /**
 137  * Fragment reassembly counter timeout
 138  *
 139  * @v timer     Retry timer
 140  * @v over      If asserted, the timer is greater than @c MAX_TIMEOUT
 141  */
 142 static void ipv4_frag_expired ( struct retry_timer *timer __unused,
 143                                 int over ) {
 144         if ( over ) {
 145                 DBG ( "Fragment reassembly timeout" );
 146                 /* Free the fragment buffer */
 147         }
 148 }
 149
 150 /**
 151  * Free fragment buffer
 152  *
 153  * @v fragbug   Fragment buffer
 154  */
 155 static void free_fragbuf ( struct frag_buffer *fragbuf ) {
 156         free ( fragbuf );
 157 }
 158
 159 /**
 160  * Fragment reassembler
 161  *
 162  * @v iobuf             I/O buffer, fragment of the datagram
 163  * @ret frag_iob        Reassembled packet, or NULL
 164  */
 165 static struct io_buffer * ipv4_reassemble ( struct io_buffer * iobuf ) {
 166         struct iphdr *iphdr = iobuf->data;
 167         struct frag_buffer *fragbuf;
 168
 169         /**
 170          * Check if the fragment belongs to any fragment series
 171          */
 172         list_for_each_entry ( fragbuf, &frag_buffers, list ) {
 173                 if ( fragbuf->ident == iphdr->ident &&
 174                      fragbuf->src.s_addr == iphdr->src.s_addr ) {
 175                         /**
 176                          * Check if the packet is the expected fragment
 177                          *
 178                          * The offset of the new packet must be equal to the
 179                          * length of the data accumulated so far (the length of
 180                          * the reassembled I/O buffer
 181                          */
 182                         if ( iob_len ( fragbuf->frag_iob ) ==
 183                               ( iphdr->frags & IP_MASK_OFFSET ) ) {
 184                                 /**
 185                                  * Append the contents of the fragment to the
 186                                  * reassembled I/O buffer
 187                                  */
 188                                 iob_pull ( iobuf, sizeof ( *iphdr ) );
 189                                 memcpy ( iob_put ( fragbuf->frag_iob,
 190                                                         iob_len ( iobuf ) ),
 191                                          iobuf->data, iob_len ( iobuf ) );
 192                                 free_iob ( iobuf );
 193
 194                                 /** Check if the fragment series is over */
 195                                 if ( ! ( iphdr->frags & IP_MASK_MOREFRAGS ) ) {
 196                                         iobuf = fragbuf->frag_iob;
 197                                         free_fragbuf ( fragbuf );
 198                                         return iobuf;
 199                                 }
 200
 201                         } else {
 202                                 /* Discard the fragment series */
 203                                 free_fragbuf ( fragbuf );
 204                                 free_iob ( iobuf );
 205                         }
 206                         return NULL;
 207                 }
 208         }
 209
 210         /** Check if the fragment is the first in the fragment series */
 211         if ( iphdr->frags & IP_MASK_MOREFRAGS &&
 212                         ( ( iphdr->frags & IP_MASK_OFFSET ) == 0 ) ) {
 213
 214                 /** Create a new fragment buffer */
 215                 fragbuf = ( struct frag_buffer* ) malloc ( sizeof( *fragbuf ) );
 216                 fragbuf->ident = iphdr->ident;
 217                 fragbuf->src = iphdr->src;
 218
 219                 /* Set up the reassembly I/O buffer */
 220                 fragbuf->frag_iob = alloc_iob ( IP_FRAG_IOB_SIZE );
 221                 iob_pull ( iobuf, sizeof ( *iphdr ) );
 222                 memcpy ( iob_put ( fragbuf->frag_iob, iob_len ( iobuf ) ),
 223                          iobuf->data, iob_len ( iobuf ) );
 224                 free_iob ( iobuf );
 225
 226                 /* Set the reassembly timer */
 227                 timer_init ( &fragbuf->frag_timer, ipv4_frag_expired );
 228                 start_timer_fixed ( &fragbuf->frag_timer, IP_FRAG_TIMEOUT );
 229
 230                 /* Add the fragment buffer to the list of fragment buffers */
 231                 list_add ( &fragbuf->list, &frag_buffers );
 232         }
 233
 234         return NULL;
 235 }
 236
 237 /**
 238  * Add IPv4 pseudo-header checksum to existing checksum
 239  *
 240  * @v iobuf             I/O buffer
 241  * @v csum              Existing checksum
 242  * @ret csum            Updated checksum
 243  */
 244 static uint16_t ipv4_pshdr_chksum ( struct io_buffer *iobuf, uint16_t csum ) {
 245         struct ipv4_pseudo_header pshdr;
 246         struct iphdr *iphdr = iobuf->data;
 247         size_t hdrlen = ( ( iphdr->verhdrlen & IP_MASK_HLEN ) * 4 );
 248
 249         /* Build pseudo-header */
 250         pshdr.src = iphdr->src;
 251         pshdr.dest = iphdr->dest;
 252         pshdr.zero_padding = 0x00;
 253         pshdr.protocol = iphdr->protocol;
 254         pshdr.len = htons ( iob_len ( iobuf ) - hdrlen );
 255
 256         /* Update the checksum value */
 257         return tcpip_continue_chksum ( csum, &pshdr, sizeof ( pshdr ) );
 258 }
 259
 260 /**
 261  * Determine link-layer address
 262  *
 263  * @v dest              IPv4 destination address
 264  * @v src               IPv4 source address
 265  * @v netdev            Network device
 266  * @v ll_dest           Link-layer destination address buffer
 267  * @ret rc              Return status code
 268  */
 269 static int ipv4_ll_addr ( struct in_addr dest, struct in_addr src,
 270                           struct net_device *netdev, uint8_t *ll_dest ) {
 271         struct ll_protocol *ll_protocol = netdev->ll_protocol;
 272
 273         if ( dest.s_addr == INADDR_BROADCAST ) {
 274                 /* Broadcast address */
 275                 memcpy ( ll_dest, netdev->ll_broadcast,
 276                          ll_protocol->ll_addr_len );
 277                 return 0;
 278         } else if ( IN_MULTICAST ( ntohl ( dest.s_addr ) ) ) {
 279                 return ll_protocol->mc_hash ( AF_INET, &dest, ll_dest );
 280         } else {
 281                 /* Unicast address: resolve via ARP */
 282                 return arp_resolve ( netdev, &ipv4_protocol, &dest,
 283                                      &src, ll_dest );
 284         }
 285 }
 286
 287 /**
 288  * Transmit IP packet
 289  *
 290  * @v iobuf             I/O buffer
 291  * @v tcpip             Transport-layer protocol
 292  * @v st_src            Source network-layer address
 293  * @v st_dest           Destination network-layer address
 294  * @v netdev            Network device to use if no route found, or NULL
 295  * @v trans_csum        Transport-layer checksum to complete, or NULL
 296  * @ret rc              Status
 297  *
 298  * This function expects a transport-layer segment and prepends the IP header
 299  */
 300 static int ipv4_tx ( struct io_buffer *iobuf,
 301                      struct tcpip_protocol *tcpip_protocol,
 302                      struct sockaddr_tcpip *st_src,
 303                      struct sockaddr_tcpip *st_dest,
 304                      struct net_device *netdev,
 305                      uint16_t *trans_csum ) {
 306         struct iphdr *iphdr = iob_push ( iobuf, sizeof ( *iphdr ) );
 307         struct sockaddr_in *sin_src = ( ( struct sockaddr_in * ) st_src );
 308         struct sockaddr_in *sin_dest = ( ( struct sockaddr_in * ) st_dest );
 309         struct ipv4_miniroute *miniroute;
 310         struct in_addr next_hop;
 311         uint8_t ll_dest[MAX_LL_ADDR_LEN];
 312         int rc;
 313
 314         /* Fill up the IP header, except source address */
 315         memset ( iphdr, 0, sizeof ( *iphdr ) );
 316         iphdr->verhdrlen = ( IP_VER | ( sizeof ( *iphdr ) / 4 ) );
 317         iphdr->service = IP_TOS;
 318         iphdr->len = htons ( iob_len ( iobuf ) );
 319         iphdr->ident = htons ( ++next_ident );
 320         iphdr->ttl = IP_TTL;
 321         iphdr->protocol = tcpip_protocol->tcpip_proto;
 322         iphdr->dest = sin_dest->sin_addr;
 323
 324         /* Use routing table to identify next hop and transmitting netdev */
 325         next_hop = iphdr->dest;
 326         if ( sin_src )
 327                 iphdr->src = sin_src->sin_addr;
 328         if ( ( next_hop.s_addr != INADDR_BROADCAST ) &&
 329              ( ! IN_MULTICAST ( ntohl ( next_hop.s_addr ) ) ) &&
 330              ( ( miniroute = ipv4_route ( &next_hop ) ) != NULL ) ) {
 331                 iphdr->src = miniroute->address;
 332                 netdev = miniroute->netdev;
 333         }
 334         if ( ! netdev ) {
 335                 DBG ( "IPv4 has no route to %s\n", inet_ntoa ( iphdr->dest ) );
 336                 rc = -ENETUNREACH;
 337                 goto err;
 338         }
 339
 340         /* Determine link-layer destination address */
 341         if ( ( rc = ipv4_ll_addr ( next_hop, iphdr->src, netdev,
 342                                    ll_dest ) ) != 0 ) {
 343                 DBG ( "IPv4 has no link-layer address for %s: %s\n",
 344                       inet_ntoa ( next_hop ), strerror ( rc ) );
 345                 goto err;
 346         }
 347
 348         /* Fix up checksums */
 349         if ( trans_csum )
 350                 *trans_csum = ipv4_pshdr_chksum ( iobuf, *trans_csum );
 351         iphdr->chksum = tcpip_chksum ( iphdr, sizeof ( *iphdr ) );
 352
 353         /* Print IP4 header for debugging */
 354         DBG ( "IPv4 TX %s->", inet_ntoa ( iphdr->src ) );
 355         DBG ( "%s len %d proto %d id %04x csum %04x\n",
 356               inet_ntoa ( iphdr->dest ), ntohs ( iphdr->len ), iphdr->protocol,
 357               ntohs ( iphdr->ident ), ntohs ( iphdr->chksum ) );
 358
 359         /* Hand off to link layer */
 360         if ( ( rc = net_tx ( iobuf, netdev, &ipv4_protocol, ll_dest ) ) != 0 ) {
 361                 DBG ( "IPv4 could not transmit packet via %s: %s\n",
 362                       netdev->name, strerror ( rc ) );
 363                 return rc;
 364         }
 365
 366         return 0;
 367
 368  err:
 369         free_iob ( iobuf );
 370         return rc;
 371 }
 372
 373 /**
 374  * Process incoming packets
 375  *
 376  * @v iobuf     I/O buffer
 377  * @v netdev    Network device
 378  * @v ll_source Link-layer destination source
 379  *
 380  * This function expects an IP4 network datagram. It processes the headers
 381  * and sends it to the transport layer.
 382  */
 383 static int ipv4_rx ( struct io_buffer *iobuf, struct net_device *netdev __unused,
 384                      const void *ll_source __unused ) {
 385         struct iphdr *iphdr = iobuf->data;
 386         size_t hdrlen;
 387         size_t len;
 388         union {
 389                 struct sockaddr_in sin;
 390                 struct sockaddr_tcpip st;
 391         } src, dest;
 392         uint16_t csum;
 393         uint16_t pshdr_csum;
 394         int rc;
 395
 396         /* Sanity check the IPv4 header */
 397         if ( iob_len ( iobuf ) < sizeof ( *iphdr ) ) {
 398                 DBG ( "IPv4 packet too short at %zd bytes (min %zd bytes)\n",
 399                       iob_len ( iobuf ), sizeof ( *iphdr ) );
 400                 goto err;
 401         }
 402         if ( ( iphdr->verhdrlen & IP_MASK_VER ) != IP_VER ) {
 403                 DBG ( "IPv4 version %#02x not supported\n", iphdr->verhdrlen );
 404                 goto err;
 405         }
 406         hdrlen = ( ( iphdr->verhdrlen & IP_MASK_HLEN ) * 4 );
 407         if ( hdrlen < sizeof ( *iphdr ) ) {
 408                 DBG ( "IPv4 header too short at %zd bytes (min %zd bytes)\n",
 409                       hdrlen, sizeof ( *iphdr ) );
 410                 goto err;
 411         }
 412         if ( hdrlen > iob_len ( iobuf ) ) {
 413                 DBG ( "IPv4 header too long at %zd bytes "
 414                       "(packet is %zd bytes)\n", hdrlen, iob_len ( iobuf ) );
 415                 goto err;
 416         }
 417         if ( ( csum = tcpip_chksum ( iphdr, hdrlen ) ) != 0 ) {
 418                 DBG ( "IPv4 checksum incorrect (is %04x including checksum "
 419                       "field, should be 0000)\n", csum );
 420                 goto err;
 421         }
 422         len = ntohs ( iphdr->len );
 423         if ( len < hdrlen ) {
 424                 DBG ( "IPv4 length too short at %zd bytes "
 425                       "(header is %zd bytes)\n", len, hdrlen );
 426                 goto err;
 427         }
 428         if ( len > iob_len ( iobuf ) ) {
 429                 DBG ( "IPv4 length too long at %zd bytes "
 430                       "(packet is %zd bytes)\n", len, iob_len ( iobuf ) );
 431                 goto err;
 432         }
 433
 434         /* Print IPv4 header for debugging */
 435         DBG ( "IPv4 RX %s<-", inet_ntoa ( iphdr->dest ) );
 436         DBG ( "%s len %d proto %d id %04x csum %04x\n",
 437               inet_ntoa ( iphdr->src ), ntohs ( iphdr->len ), iphdr->protocol,
 438               ntohs ( iphdr->ident ), ntohs ( iphdr->chksum ) );
 439
 440         /* Truncate packet to correct length, calculate pseudo-header
 441          * checksum and then strip off the IPv4 header.
 442          */
 443         iob_unput ( iobuf, ( iob_len ( iobuf ) - len ) );
 444         pshdr_csum = ipv4_pshdr_chksum ( iobuf, TCPIP_EMPTY_CSUM );
 445         iob_pull ( iobuf, hdrlen );
 446
 447         /* Fragment reassembly */
 448         if ( ( iphdr->frags & htons ( IP_MASK_MOREFRAGS ) ) ||
 449              ( ( iphdr->frags & htons ( IP_MASK_OFFSET ) ) != 0 ) ) {
 450                 /* Pass the fragment to ipv4_reassemble() which either
 451                  * returns a fully reassembled I/O buffer or NULL.
 452                  */
 453                 iobuf = ipv4_reassemble ( iobuf );
 454                 if ( ! iobuf )
 455                         return 0;
 456         }
 457
 458         /* Construct socket addresses and hand off to transport layer */
 459         memset ( &src, 0, sizeof ( src ) );
 460         src.sin.sin_family = AF_INET;
 461         src.sin.sin_addr = iphdr->src;
 462         memset ( &dest, 0, sizeof ( dest ) );
 463         dest.sin.sin_family = AF_INET;
 464         dest.sin.sin_addr = iphdr->dest;
 465         if ( ( rc = tcpip_rx ( iobuf, iphdr->protocol, &src.st,
 466                                &dest.st, pshdr_csum ) ) != 0 ) {
 467                 DBG ( "IPv4 received packet rejected by stack: %s\n",
 468                       strerror ( rc ) );
 469                 return rc;
 470         }
 471
 472         return 0;
 473
 474  err:
 475         free_iob ( iobuf );
 476         return -EINVAL;
 477 }
 478
 479 /**
 480  * Check existence of IPv4 address for ARP
 481  *
 482  * @v netdev            Network device
 483  * @v net_addr          Network-layer address
 484  * @ret rc              Return status code
 485  */
 486 static int ipv4_arp_check ( struct net_device *netdev, const void *net_addr ) {
 487         const struct in_addr *address = net_addr;
 488         struct ipv4_miniroute *miniroute;
 489
 490         list_for_each_entry ( miniroute, &ipv4_miniroutes, list ) {
 491                 if ( ( miniroute->netdev == netdev ) &&
 492                      ( miniroute->address.s_addr == address->s_addr ) ) {
 493                         /* Found matching address */
 494                         return 0;
 495                 }
 496         }
 497         return -ENOENT;
 498 }
 499
 500 /**
 501  * Convert IPv4 address to dotted-quad notation
 502  *
 503  * @v in        IP address
 504  * @ret string  IP address in dotted-quad notation
 505  */
 506 char * inet_ntoa ( struct in_addr in ) {
 507         static char buf[16]; /* "xxx.xxx.xxx.xxx" */
 508         uint8_t *bytes = ( uint8_t * ) &in;
 509
 510         sprintf ( buf, "%d.%d.%d.%d", bytes[0], bytes[1], bytes[2], bytes[3] );
 511         return buf;
 512 }
 513
 514 /**
 515  * Transcribe IP address
 516  *
 517  * @v net_addr  IP address
 518  * @ret string  IP address in dotted-quad notation
 519  *
 520  */
 521 static const char * ipv4_ntoa ( const void *net_addr ) {
 522         return inet_ntoa ( * ( ( struct in_addr * ) net_addr ) );
 523 }
 524
 525 /** IPv4 protocol */
 526 struct net_protocol ipv4_protocol __net_protocol = {
 527         .name = "IP",
 528         .net_proto = htons ( ETH_P_IP ),
 529         .net_addr_len = sizeof ( struct in_addr ),
 530         .rx = ipv4_rx,
 531         .ntoa = ipv4_ntoa,
 532 };
 533
 534 /** IPv4 TCPIP net protocol */
 535 struct tcpip_net_protocol ipv4_tcpip_protocol __tcpip_net_protocol = {
 536         .name = "IPv4",
 537         .sa_family = AF_INET,
 538         .tx = ipv4_tx,
 539 };
 540
 541 /** IPv4 ARP protocol */
 542 struct arp_net_protocol ipv4_arp_protocol __arp_net_protocol = {
 543         .net_protocol = &ipv4_protocol,
 544         .check = ipv4_arp_check,
 545 };
 546
 547 /******************************************************************************
 548  *
 549  * Settings
 550  *
 551  ******************************************************************************
 552  */
 553
 554 /** IPv4 address setting */
 555 struct setting ip_setting __setting = {
 556         .name = "ip",
 557         .description = "IPv4 address",
 558         .tag = DHCP_EB_YIADDR,
 559         .type = &setting_type_ipv4,
 560 };
 561
 562 /** IPv4 subnet mask setting */
 563 struct setting netmask_setting __setting = {
 564         .name = "netmask",
 565         .description = "IPv4 subnet mask",
 566         .tag = DHCP_SUBNET_MASK,
 567         .type = &setting_type_ipv4,
 568 };
 569
 570 /** Default gateway setting */
 571 struct setting gateway_setting __setting = {
 572         .name = "gateway",
 573         .description = "Default gateway",
 574         .tag = DHCP_ROUTERS,
 575         .type = &setting_type_ipv4,
 576 };
 577
 578 /**
 579  * Create IPv4 routing table based on configured settings
 580  *
 581  * @ret rc              Return status code
 582  */
 583 static int ipv4_create_routes ( void ) {
 584         struct ipv4_miniroute *miniroute;
 585         struct ipv4_miniroute *tmp;
 586         struct net_device *netdev;
 587         struct settings *settings;
 588         struct in_addr address = { 0 };
 589         struct in_addr netmask = { 0 };
 590         struct in_addr gateway = { 0 };
 591
 592         /* Delete all existing routes */
 593         list_for_each_entry_safe ( miniroute, tmp, &ipv4_miniroutes, list )
 594                 del_ipv4_miniroute ( miniroute );
 595
 596         /* Create a route for each configured network device */
 597         for_each_netdev ( netdev ) {
 598                 settings = netdev_settings ( netdev );
 599                 /* Get IPv4 address */
 600                 address.s_addr = 0;
 601                 fetch_ipv4_setting ( settings, &ip_setting, &address );
 602                 if ( ! address.s_addr )
 603                         continue;
 604                 /* Get subnet mask */
 605                 fetch_ipv4_setting ( settings, &netmask_setting, &netmask );
 606                 /* Calculate default netmask, if necessary */
 607                 if ( ! netmask.s_addr ) {
 608                         if ( IN_CLASSA ( ntohl ( address.s_addr ) ) ) {
 609                                 netmask.s_addr = htonl ( IN_CLASSA_NET );
 610                         } else if ( IN_CLASSB ( ntohl ( address.s_addr ) ) ) {
 611                                 netmask.s_addr = htonl ( IN_CLASSB_NET );
 612                         } else if ( IN_CLASSC ( ntohl ( address.s_addr ) ) ) {
 613                                 netmask.s_addr = htonl ( IN_CLASSC_NET );
 614                         }
 615                 }
 616                 /* Get default gateway, if present */
 617                 fetch_ipv4_setting ( settings, &gateway_setting, &gateway );
 618                 /* Configure route */
 619                 miniroute = add_ipv4_miniroute ( netdev, address,
 620                                                  netmask, gateway );
 621                 if ( ! miniroute )
 622                         return -ENOMEM;
 623         }
 624
 625         return 0;
 626 }
 627
 628 /** IPv4 settings applicator */
 629 struct settings_applicator ipv4_settings_applicator __settings_applicator = {
 630         .apply = ipv4_create_routes,
 631 };
 632
 633 /* Drag in ICMP */
 634 REQUIRE_OBJECT ( icmp );