core/ipv4/autoip.c

0001 /**
0002  * @file
0003  * AutoIP Automatic LinkLocal IP Configuration
0004  *
0005  */
0006
0007 /*
0008  *
0009  * Copyright (c) 2007 Dominik Spies <kontakt@dspies.de>
0010  * All rights reserved.
0011  *
0012  * Redistribution and use in source and binary forms, with or without modification,
0013  * are permitted provided that the following conditions are met:
0014  *
0015  * 1. Redistributions of source code must retain the above copyright notice,
0016  *    this list of conditions and the following disclaimer.
0017  * 2. Redistributions in binary form must reproduce the above copyright notice,
0018  *    this list of conditions and the following disclaimer in the documentation
0019  *    and/or other materials provided with the distribution.
0020  * 3. The name of the author may not be used to endorse or promote products
0021  *    derived from this software without specific prior written permission.
0022  *
0023  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
0024  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
0025  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
0026  * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
0027  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
0028  * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
0029  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
0030  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
0031  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
0032  * OF SUCH DAMAGE.
0033  *
0034  * Author: Dominik Spies <kontakt@dspies.de>
0035  *
0036  * This is a AutoIP implementation for the lwIP TCP/IP stack. It aims to conform
0037  * with RFC 3927.
0038  *
0039  *
0040  * Please coordinate changes and requests with Dominik Spies
0041  * <kontakt@dspies.de>
0042  */
0043
0044 /*******************************************************************************
0045  * USAGE:
0046  *
0047  * define LWIP_AUTOIP 1  in your lwipopts.h
0048  *
0049  * If you don't use tcpip.c (so, don't call, you don't call tcpip_init):
0050  * - First, call autoip_init().
0051  * - call autoip_tmr() all AUTOIP_TMR_INTERVAL msces,
0052  *   that should be defined in autoip.h.
0053  *   I recommend a value of 100. The value must divide 1000 with a remainder almost 0.
0054  *   Possible values are 1000, 500, 333, 250, 200, 166, 142, 125, 111, 100 ....
0055  *
0056  * Without DHCP:
0057  * - Call autoip_start() after netif_add().
0058  *
0059  * With DHCP:
0060  * - define LWIP_DHCP_AUTOIP_COOP 1 in your lwipopts.h.
0061  * - Configure your DHCP Client.
0062  *
0063  */
0064
0065 #include "lwip/opt.h"
0066
0067 #if LWIP_AUTOIP /* don't build if not configured for use in lwipopts.h */
0068
0069 #include "lwip/mem.h"
0070 #include "lwip/udp.h"
0071 #include "lwip/ip_addr.h"
0072 #include "lwip/netif.h"
0073 #include "lwip/autoip.h"
0074 #include "netif/etharp.h"
0075
0076 #include <stdlib.h>
0077 #include <string.h>
0078
0079 /* 169.254.0.0 */
0080 #define AUTOIP_NET         0xA9FE0000
0081 /* 169.254.1.0 */
0082 #define AUTOIP_RANGE_START (AUTOIP_NET | 0x0100)
0083 /* 169.254.254.255 */
0084 #define AUTOIP_RANGE_END   (AUTOIP_NET | 0xFEFF)
0085
0086
0087 /** Pseudo random macro based on netif informations.
0088  * You could use "rand()" from the C Library if you define LWIP_AUTOIP_RAND in lwipopts.h */
0089 #ifndef LWIP_AUTOIP_RAND
0090 #define LWIP_AUTOIP_RAND(netif) ( (((u32_t)((netif->hwaddr[5]) & 0xff) << 24) | \
0091                                    ((u32_t)((netif->hwaddr[3]) & 0xff) << 16) | \
0092                                    ((u32_t)((netif->hwaddr[2]) & 0xff) << 8) | \
0093                                    ((u32_t)((netif->hwaddr[4]) & 0xff))) + \
0094                                    (netif->autoip?netif->autoip->tried_llipaddr:0))
0095 #endif /* LWIP_AUTOIP_RAND */
0096
0097 /**
0098  * Macro that generates the initial IP address to be tried by AUTOIP.
0099  * If you want to override this, define it to something else in lwipopts.h.
0100  */
0101 #ifndef LWIP_AUTOIP_CREATE_SEED_ADDR
0102 #define LWIP_AUTOIP_CREATE_SEED_ADDR(netif) \
0103   htonl(AUTOIP_RANGE_START + ((u32_t)(((u8_t)(netif->hwaddr[4])) | \
0104                  ((u32_t)((u8_t)(netif->hwaddr[5]))) << 8)))
0105 #endif /* LWIP_AUTOIP_CREATE_SEED_ADDR */
0106
0107 /* static functions */
0108 static void autoip_handle_arp_conflict(struct netif *netif);
0109
0110 /* creates a pseudo random LL IP-Address for a network interface */
0111 static void autoip_create_addr(struct netif *netif, struct ip_addr *ipaddr);
0112
0113 /* sends an ARP probe */
0114 static err_t autoip_arp_probe(struct netif *netif);
0115
0116 /* sends an ARP announce */
0117 static err_t autoip_arp_announce(struct netif *netif);
0118
0119 /* configure interface for use with current LL IP-Address */
0120 static err_t autoip_bind(struct netif *netif);
0121
0122 /* start sending probes for llipaddr */
0123 static void autoip_start_probing(struct netif *netif);
0124
0125 /**
0126  * Initialize this module
0127  */
0128 void
0129 autoip_init(void)
0130 {
0131   LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE, ("autoip_init()\n"));
0132 }
0133
0134 /**
0135  * Handle a IP address conflict after an ARP conflict detection
0136  */
0137 static void
0138 autoip_handle_arp_conflict(struct netif *netif)
0139 {
0140   /* Somehow detect if we are defending or retreating */
0141   unsigned char defend = 1; /* tbd */
0142
0143   if(defend) {
0144     if(netif->autoip->lastconflict > 0) {
0145       /* retreat, there was a conflicting ARP in the last
0146        * DEFEND_INTERVAL seconds
0147        */
0148       LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE,
0149         ("autoip_handle_arp_conflict(): we are defending, but in DEFEND_INTERVAL, retreating\n"));
0150
0151       /* TODO: close all TCP sessions */
0152       autoip_start(netif);
0153     } else {
0154       LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE,
0155         ("autoip_handle_arp_conflict(): we are defend, send ARP Announce\n"));
0156       autoip_arp_announce(netif);
0157       netif->autoip->lastconflict = DEFEND_INTERVAL * AUTOIP_TICKS_PER_SECOND;
0158     }
0159   } else {
0160     LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE,
0161       ("autoip_handle_arp_conflict(): we do not defend, retreating\n"));
0162     /* TODO: close all TCP sessions */
0163     autoip_start(netif);
0164   }
0165 }
0166
0167 /**
0168  * Create an IP-Address out of range 169.254.1.0 to 169.254.254.255
0169  *
0170  * @param netif network interface on which create the IP-Address
0171  * @param ipaddr ip address to initialize
0172  */
0173 static void
0174 autoip_create_addr(struct netif *netif, struct ip_addr *ipaddr)
0175 {
0176   /* Here we create an IP-Address out of range 169.254.1.0 to 169.254.254.255
0177    * compliant to RFC 3927 Section 2.1
0178    * We have 254 * 256 possibilities */
0179
0180   u32_t addr = ntohl(LWIP_AUTOIP_CREATE_SEED_ADDR(netif));
0181   addr += netif->autoip->tried_llipaddr;
0182   addr = AUTOIP_NET | (addr & 0xffff);
0183   /* Now, 169.254.0.0 <= addr <= 169.254.255.255 */
0184
0185   if (addr < AUTOIP_RANGE_START) {
0186     addr += AUTOIP_RANGE_END - AUTOIP_RANGE_START + 1;
0187   }
0188   if (addr > AUTOIP_RANGE_END) {
0189     addr -= AUTOIP_RANGE_END - AUTOIP_RANGE_START + 1;
0190   }
0191   LWIP_ASSERT("AUTOIP address not in range", (addr >= AUTOIP_RANGE_START) &&
0192     (addr <= AUTOIP_RANGE_END));
0193   ipaddr->addr = htonl(addr);
0194
0195   LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE,
0196     ("autoip_create_addr(): tried_llipaddr=%"U16_F", 0x%08"X32_F"\n",
0197     (u16_t)(netif->autoip->tried_llipaddr), (u32_t)(ipaddr->addr)));
0198 }
0199
0200 /**
0201  * Sends an ARP probe from a network interface
0202  *
0203  * @param netif network interface used to send the probe
0204  */
0205 static err_t
0206 autoip_arp_probe(struct netif *netif)
0207 {
0208   return etharp_raw(netif, (struct eth_addr *)netif->hwaddr, &ethbroadcast,
0209     (struct eth_addr *)netif->hwaddr, IP_ADDR_ANY, &ethzero,
0210     &netif->autoip->llipaddr, ARP_REQUEST);
0211 }
0212
0213 /**
0214  * Sends an ARP announce from a network interface
0215  *
0216  * @param netif network interface used to send the announce
0217  */
0218 static err_t
0219 autoip_arp_announce(struct netif *netif)
0220 {
0221   return etharp_raw(netif, (struct eth_addr *)netif->hwaddr, &ethbroadcast,
0222     (struct eth_addr *)netif->hwaddr, &netif->autoip->llipaddr, &ethzero,
0223     &netif->autoip->llipaddr, ARP_REQUEST);
0224 }
0225
0226 /**
0227  * Configure interface for use with current LL IP-Address
0228  *
0229  * @param netif network interface to configure with current LL IP-Address
0230  */
0231 static err_t
0232 autoip_bind(struct netif *netif)
0233 {
0234   struct autoip *autoip = netif->autoip;
0235   struct ip_addr sn_mask, gw_addr;
0236
0237   LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE,
0238     ("autoip_bind(netif=%p) %c%c%"U16_F" 0x%08"X32_F"\n",
0239     (void*)netif, netif->name[0], netif->name[1], (u16_t)netif->num, autoip->llipaddr.addr));
0240
0241   IP4_ADDR(&sn_mask, 255, 255, 0, 0);
0242   IP4_ADDR(&gw_addr, 0, 0, 0, 0);
0243
0244   netif_set_ipaddr(netif, &autoip->llipaddr);
0245   netif_set_netmask(netif, &sn_mask);
0246   netif_set_gw(netif, &gw_addr);
0247
0248   /* bring the interface up */
0249   netif_set_up(netif);
0250
0251   return ERR_OK;
0252 }
0253
0254 /**
0255  * Start AutoIP client
0256  *
0257  * @param netif network interface on which start the AutoIP client
0258  */
0259 err_t
0260 autoip_start(struct netif *netif)
0261 {
0262   struct autoip *autoip = netif->autoip;
0263   err_t result = ERR_OK;
0264
0265   if(netif_is_up(netif)) {
0266     netif_set_down(netif);
0267   }
0268
0269   /* Set IP-Address, Netmask and Gateway to 0 to make sure that
0270    * ARP Packets are formed correctly
0271    */
0272   netif->ip_addr.addr = 0;
0273   netif->netmask.addr = 0;
0274   netif->gw.addr      = 0;
0275
0276   LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE,
0277     ("autoip_start(netif=%p) %c%c%"U16_F"\n", (void*)netif, netif->name[0],
0278     netif->name[1], (u16_t)netif->num));
0279   if(autoip == NULL) {
0280     /* no AutoIP client attached yet? */
0281     LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE,
0282       ("autoip_start(): starting new AUTOIP client\n"));
0283     autoip = mem_malloc(sizeof(struct autoip));
0284     if(autoip == NULL) {
0285       LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE,
0286         ("autoip_start(): could not allocate autoip\n"));
0287       return ERR_MEM;
0288     }
0289     memset( autoip, 0, sizeof(struct autoip));
0290     /* store this AutoIP client in the netif */
0291     netif->autoip = autoip;
0292     LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE, ("autoip_start(): allocated autoip"));
0293   } else {
0294     autoip->state = AUTOIP_STATE_OFF;
0295     autoip->ttw = 0;
0296     autoip->sent_num = 0;
0297     memset(&autoip->llipaddr, 0, sizeof(struct ip_addr));
0298     autoip->lastconflict = 0;
0299   }
0300
0301   autoip_create_addr(netif, &(autoip->llipaddr));
0302   autoip->tried_llipaddr++;
0303   autoip_start_probing(netif);
0304
0305   return result;
0306 }
0307
0308 static void
0309 autoip_start_probing(struct netif *netif)
0310 {
0311   struct autoip *autoip = netif->autoip;
0312
0313   autoip->state = AUTOIP_STATE_PROBING;
0314   autoip->sent_num = 0;
0315
0316   /* time to wait to first probe, this is randomly
0317    * choosen out of 0 to PROBE_WAIT seconds.
0318    * compliant to RFC 3927 Section 2.2.1
0319    */
0320   autoip->ttw = (u16_t)(LWIP_AUTOIP_RAND(netif) % (PROBE_WAIT * AUTOIP_TICKS_PER_SECOND));
0321
0322   /*
0323    * if we tried more then MAX_CONFLICTS we must limit our rate for
0324    * accquiring and probing address
0325    * compliant to RFC 3927 Section 2.2.1
0326    */
0327   if(autoip->tried_llipaddr > MAX_CONFLICTS) {
0328     autoip->ttw = RATE_LIMIT_INTERVAL * AUTOIP_TICKS_PER_SECOND;
0329   }
0330 }
0331
0332 /**
0333  * Handle a possible change in the network configuration.
0334  *
0335  * If there is an AutoIP address configured, take the interface down
0336  * and begin probing with the same address.
0337  */
0338 void
0339 autoip_network_changed(struct netif *netif)
0340 {
0341   if (netif->autoip && netif->autoip->state != AUTOIP_STATE_OFF) {
0342     netif_set_down(netif);
0343     autoip_start_probing(netif);
0344   }
0345 }
0346
0347 /**
0348  * Stop AutoIP client
0349  *
0350  * @param netif network interface on which stop the AutoIP client
0351  */
0352 err_t
0353 autoip_stop(struct netif *netif)
0354 {
0355   netif->autoip->state = AUTOIP_STATE_OFF;
0356   netif_set_down(netif);
0357   return ERR_OK;
0358 }
0359
0360 /**
0361  * Has to be called in loop every AUTOIP_TMR_INTERVAL milliseconds
0362  */
0363 void
0364 autoip_tmr()
0365 {
0366   struct netif *netif = netif_list;
0367   /* loop through netif's */
0368   while (netif != NULL) {
0369     /* only act on AutoIP configured interfaces */
0370     if (netif->autoip != NULL) {
0371       if(netif->autoip->lastconflict > 0) {
0372         netif->autoip->lastconflict--;
0373       }
0374
0375       LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE,
0376         ("autoip_tmr() AutoIP-State: %"U16_F", ttw=%"U16_F"\n",
0377         (u16_t)(netif->autoip->state), netif->autoip->ttw));
0378
0379       switch(netif->autoip->state) {
0380         case AUTOIP_STATE_PROBING:
0381           if(netif->autoip->ttw > 0) {
0382             netif->autoip->ttw--;
0383           } else {
0384             if(netif->autoip->sent_num >= PROBE_NUM) {
0385               netif->autoip->state = AUTOIP_STATE_ANNOUNCING;
0386               netif->autoip->sent_num = 0;
0387               netif->autoip->ttw = ANNOUNCE_WAIT * AUTOIP_TICKS_PER_SECOND;
0388             } else {
0389               autoip_arp_probe(netif);
0390               LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE,
0391                 ("autoip_tmr() PROBING Sent Probe\n"));
0392               netif->autoip->sent_num++;
0393               /* calculate time to wait to next probe */
0394               netif->autoip->ttw = (u16_t)((LWIP_AUTOIP_RAND(netif) %
0395                 ((PROBE_MAX - PROBE_MIN) * AUTOIP_TICKS_PER_SECOND) ) +
0396                 PROBE_MIN * AUTOIP_TICKS_PER_SECOND);
0397             }
0398           }
0399           break;
0400
0401         case AUTOIP_STATE_ANNOUNCING:
0402           if(netif->autoip->ttw > 0) {
0403             netif->autoip->ttw--;
0404           } else {
0405             if(netif->autoip->sent_num == 0) {
0406              /* We are here the first time, so we waited ANNOUNCE_WAIT seconds
0407               * Now we can bind to an IP address and use it.
0408               *
0409               * autoip_bind calls netif_set_up. This triggers a gratuitous ARP
0410               * which counts as an announcement.
0411               */
0412               autoip_bind(netif);
0413             } else {
0414               autoip_arp_announce(netif);
0415               LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE,
0416                 ("autoip_tmr() ANNOUNCING Sent Announce\n"));
0417             }
0418             netif->autoip->ttw = ANNOUNCE_INTERVAL * AUTOIP_TICKS_PER_SECOND;
0419             netif->autoip->sent_num++;
0420
0421             if(netif->autoip->sent_num >= ANNOUNCE_NUM) {
0422                 netif->autoip->state = AUTOIP_STATE_BOUND;
0423                 netif->autoip->sent_num = 0;
0424                 netif->autoip->ttw = 0;
0425             }
0426           }
0427           break;
0428       }
0429     }
0430     /* proceed to next network interface */
0431     netif = netif->next;
0432   }
0433 }
0434
0435 /**
0436  * Handles every incoming ARP Packet, called by etharp_arp_input.
0437  *
0438  * @param netif network interface to use for autoip processing
0439  * @param hdr Incoming ARP packet
0440  */
0441 void
0442 autoip_arp_reply(struct netif *netif, struct etharp_hdr *hdr)
0443 {
0444   LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE, ("autoip_arp_reply()\n"));
0445   if ((netif->autoip != NULL) && (netif->autoip->state != AUTOIP_STATE_OFF)) {
0446    /* when ip.src == llipaddr && hw.src != netif->hwaddr
0447     *
0448     * when probing  ip.dst == llipaddr && hw.src != netif->hwaddr
0449     * we have a conflict and must solve it
0450     */
0451     struct ip_addr sipaddr, dipaddr;
0452     struct eth_addr netifaddr;
0453     netifaddr.addr[0] = netif->hwaddr[0];
0454     netifaddr.addr[1] = netif->hwaddr[1];
0455     netifaddr.addr[2] = netif->hwaddr[2];
0456     netifaddr.addr[3] = netif->hwaddr[3];
0457     netifaddr.addr[4] = netif->hwaddr[4];
0458     netifaddr.addr[5] = netif->hwaddr[5];
0459
0460     /* Copy struct ip_addr2 to aligned ip_addr, to support compilers without
0461      * structure packing (not using structure copy which breaks strict-aliasing rules).
0462      */
0463     SMEMCPY(&sipaddr, &hdr->sipaddr, sizeof(sipaddr));
0464     SMEMCPY(&dipaddr, &hdr->dipaddr, sizeof(dipaddr));
0465
0466     if ((netif->autoip->state == AUTOIP_STATE_PROBING) ||
0467         ((netif->autoip->state == AUTOIP_STATE_ANNOUNCING) &&
0468          (netif->autoip->sent_num == 0))) {
0469      /* RFC 3927 Section 2.2.1:
0470       * from beginning to after ANNOUNCE_WAIT
0471       * seconds we have a conflict if
0472       * ip.src == llipaddr OR
0473       * ip.dst == llipaddr && hw.src != own hwaddr
0474       */
0475       if ((ip_addr_cmp(&sipaddr, &netif->autoip->llipaddr)) ||
0476           (ip_addr_cmp(&dipaddr, &netif->autoip->llipaddr) &&
0477            !eth_addr_cmp(&netifaddr, &hdr->shwaddr))) {
0478         LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE | LWIP_DBG_LEVEL_WARNING,
0479           ("autoip_arp_reply(): Probe Conflict detected\n"));
0480         autoip_start(netif);
0481       }
0482     } else {
0483      /* RFC 3927 Section 2.5:
0484       * in any state we have a conflict if
0485       * ip.src == llipaddr && hw.src != own hwaddr
0486       */
0487       if (ip_addr_cmp(&sipaddr, &netif->autoip->llipaddr) &&
0488           !eth_addr_cmp(&netifaddr, &hdr->shwaddr)) {
0489         LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE | LWIP_DBG_LEVEL_WARNING,
0490           ("autoip_arp_reply(): Conflicting ARP-Packet detected\n"));
0491         autoip_handle_arp_conflict(netif);
0492       }
0493     }
0494   }
0495 }
0496
0497 #endif /* LWIP_AUTOIP */