autoip.c

00001 /**
00002  * @file
00003  * AutoIP Automatic LinkLocal IP Configuration
00004  *
00005  */
00006 
00007 /*
00008  *
00009  * Copyright (c) 2007 Dominik Spies <kontakt@dspies.de>
00010  * All rights reserved.
00011  *
00012  * Redistribution and use in source and binary forms, with or without modification,
00013  * are permitted provided that the following conditions are met:
00014  *
00015  * 1. Redistributions of source code must retain the above copyright notice,
00016  *    this list of conditions and the following disclaimer.
00017  * 2. Redistributions in binary form must reproduce the above copyright notice,
00018  *    this list of conditions and the following disclaimer in the documentation
00019  *    and/or other materials provided with the distribution.
00020  * 3. The name of the author may not be used to endorse or promote products
00021  *    derived from this software without specific prior written permission.
00022  *
00023  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
00024  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
00025  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
00026  * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
00027  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
00028  * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
00029  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
00030  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
00031  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
00032  * OF SUCH DAMAGE.
00033  *
00034  * Author: Dominik Spies <kontakt@dspies.de>
00035  *
00036  * This is a AutoIP implementation for the lwIP TCP/IP stack. It aims to conform
00037  * with RFC 3927.
00038  *
00039  *
00040  * Please coordinate changes and requests with Dominik Spies
00041  * <kontakt@dspies.de>
00042  */
00043 
00044 /*******************************************************************************
00045  * USAGE:
00046  * 
00047  * define LWIP_AUTOIP 1  in your lwipopts.h
00048  * 
00049  * If you don't use tcpip.c (so, don't call, you don't call tcpip_init):
00050  * - First, call autoip_init().
00051  * - call autoip_tmr() all AUTOIP_TMR_INTERVAL msces,
00052  *   that should be defined in autoip.h.
00053  *   I recommend a value of 100. The value must divide 1000 with a remainder almost 0.
00054  *   Possible values are 1000, 500, 333, 250, 200, 166, 142, 125, 111, 100 ....
00055  *
00056  * Without DHCP:
00057  * - Call autoip_start() after netif_add().
00058  * 
00059  * With DHCP:
00060  * - define LWIP_DHCP_AUTOIP_COOP 1 in your lwipopts.h.
00061  * - Configure your DHCP Client.
00062  *
00063  */
00064 
00065 #include "lwip/opt.h"
00066 
00067 #if LWIP_AUTOIP /* don't build if not configured for use in lwipopts.h */
00068 
00069 #include "lwip/mem.h"
00070 #include "lwip/udp.h"
00071 #include "lwip/ip_addr.h"
00072 #include "lwip/netif.h"
00073 #include "lwip/autoip.h"
00074 #include "netif/etharp.h"
00075 
00076 #include <stdlib.h>
00077 #include <string.h>
00078 
00079 /* 169.254.0.0 */
00080 #define AUTOIP_NET         0xA9FE0000
00081 /* 169.254.1.0 */
00082 #define AUTOIP_RANGE_START (AUTOIP_NET | 0x0100)
00083 /* 169.254.254.255 */
00084 #define AUTOIP_RANGE_END   (AUTOIP_NET | 0xFEFF)
00085 
00086 
00087 /** Pseudo random macro based on netif informations.
00088  * You could use "rand()" from the C Library if you define LWIP_AUTOIP_RAND in lwipopts.h */
00089 #ifndef LWIP_AUTOIP_RAND
00090 #define LWIP_AUTOIP_RAND(netif) ( (((u32_t)((netif->hwaddr[5]) & 0xff) << 24) | \
00091                                    ((u32_t)((netif->hwaddr[3]) & 0xff) << 16) | \
00092                                    ((u32_t)((netif->hwaddr[2]) & 0xff) << 8) | \
00093                                    ((u32_t)((netif->hwaddr[4]) & 0xff))) + \
00094                                    (netif->autoip?netif->autoip->tried_llipaddr:0))
00095 #endif /* LWIP_AUTOIP_RAND */
00096 
00097 /**
00098  * Macro that generates the initial IP address to be tried by AUTOIP.
00099  * If you want to override this, define it to something else in lwipopts.h.
00100  */
00101 #ifndef LWIP_AUTOIP_CREATE_SEED_ADDR
00102 #define LWIP_AUTOIP_CREATE_SEED_ADDR(netif) \
00103   (AUTOIP_RANGE_START + ((u32_t)(((u8_t)(netif->hwaddr[4])) | \
00104                  ((u32_t)((u8_t)(netif->hwaddr[5]))) << 8)))
00105 #endif /* LWIP_AUTOIP_CREATE_SEED_ADDR */
00106 
00107 /* static functions */
00108 static void autoip_handle_arp_conflict(struct netif *netif);
00109 
00110 /* creates a pseudo random LL IP-Address for a network interface */
00111 static void autoip_create_addr(struct netif *netif, struct ip_addr *IPAddr);
00112 
00113 /* sends an ARP announce */
00114 static err_t autoip_arp_announce(struct netif *netif);
00115 
00116 /* configure interface for use with current LL IP-Address */
00117 static err_t autoip_bind(struct netif *netif);
00118 
00119 /**
00120  * Initialize this module
00121  */
00122 void
00123 autoip_init(void)
00124 {
00125   LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE | 3, ("autoip_init()\n"));
00126 }
00127 
00128 /**
00129  * Handle a IP address conflict after an ARP conflict detection
00130  */
00131 static void
00132 autoip_handle_arp_conflict(struct netif *netif)
00133 {
00134   /* Somehow detect if we are defending or retreating */
00135   unsigned char defend = 1; /* tbd */
00136 
00137   if(defend) {
00138     if(netif->autoip->lastconflict > 0) {
00139       /* retreat, there was a conflicting ARP in the last
00140        * DEFEND_INTERVAL seconds
00141        */
00142       LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE | 1,
00143         ("autoip_handle_arp_conflict(): we are defending, but in DEFEND_INTERVAL, retreating\n"));
00144 
00145       /* TODO: close all TCP sessions */
00146       autoip_start(netif);
00147     } else {
00148       LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE | 1,
00149         ("autoip_handle_arp_conflict(): we are defend, send ARP Announce\n"));
00150       autoip_arp_announce(netif);
00151       netif->autoip->lastconflict = DEFEND_INTERVAL * AUTOIP_TICKS_PER_SECOND;
00152     }
00153   } else {
00154     LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE | 1,
00155       ("autoip_handle_arp_conflict(): we do not defend, retreating\n"));
00156     /* TODO: close all TCP sessions */
00157     autoip_start(netif);
00158   }
00159 }
00160 
00161 /**
00162  * Create an IP-Address out of range 169.254.1.0 to 169.254.254.255
00163  *
00164  * @param netif network interface on which create the IP-Address
00165  * @param IPAddr ip address to initialize
00166  */
00167 static void
00168 autoip_create_addr(struct netif *netif, struct ip_addr *IPAddr)
00169 {
00170   /* Here we create an IP-Address out of range 169.254.1.0 to 169.254.254.255
00171    * compliant to RFC 3927 Section 2.1
00172    * We have 254 * 256 possibilities */
00173 
00174   u32_t addr = ntohl(LWIP_AUTOIP_CREATE_SEED_ADDR(netif));
00175   addr += netif->autoip->tried_llipaddr;
00176   addr = AUTOIP_NET | (addr & 0xffff);
00177   /* Now, 169.254.0.0 <= addr <= 169.254.255.255 */ 
00178 
00179   if (addr < AUTOIP_RANGE_START) {
00180     addr += AUTOIP_RANGE_END - AUTOIP_RANGE_START + 1;
00181   }
00182   if (addr > AUTOIP_RANGE_END) {
00183     addr -= AUTOIP_RANGE_END - AUTOIP_RANGE_START + 1;
00184   }
00185   LWIP_ASSERT("AUTOIP address not in range", (addr >= AUTOIP_RANGE_START) &&
00186     (addr <= AUTOIP_RANGE_END));
00187   IPAddr->addr = htonl(addr);
00188   
00189   LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE | 1,
00190     ("autoip_create_addr(): tried_llipaddr=%"U16_F", 0x%08"X32_F"\n",
00191     (u16_t)(netif->autoip->tried_llipaddr), (u32_t)(IPAddr->addr)));
00192 }
00193 
00194 /**
00195  * Sends an ARP announce from a network interface
00196  *
00197  * @param netif network interface used to send the announce
00198  */
00199 static err_t
00200 autoip_arp_announce(struct netif *netif)
00201 {
00202   return etharp_raw(netif, (struct eth_addr *)netif->hwaddr, &ethbroadcast,
00203     (struct eth_addr *)netif->hwaddr, &netif->autoip->llipaddr, &ethzero,
00204     &netif->autoip->llipaddr, ARP_REQUEST);
00205 }
00206 
00207 /**
00208  * Configure interface for use with current LL IP-Address
00209  *
00210  * @param netif network interface to configure with current LL IP-Address
00211  */
00212 static err_t
00213 autoip_bind(struct netif *netif)
00214 {
00215   struct autoip *autoip = netif->autoip;
00216   struct ip_addr sn_mask, gw_addr;
00217 
00218   LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE | 3,
00219     ("autoip_bind(netif=%p) %c%c%"U16_F" 0x%08"X32_F"\n",
00220     (void*)netif, netif->name[0], netif->name[1], (u16_t)netif->num, autoip->llipaddr.addr));
00221 
00222   IP4_ADDR(&sn_mask, 255, 255, 0, 0);
00223   IP4_ADDR(&gw_addr, 0, 0, 0, 0);
00224 
00225   netif_set_ipaddr(netif, &autoip->llipaddr);
00226   netif_set_netmask(netif, &sn_mask);
00227   netif_set_gw(netif, &gw_addr);  
00228 
00229   /* bring the interface up */
00230   netif_set_up(netif);
00231 
00232   return ERR_OK;
00233 }
00234 
00235 /**
00236  * Start AutoIP client
00237  *
00238  * @param netif network interface on which start the AutoIP client
00239  */
00240 err_t
00241 autoip_start(struct netif *netif)
00242 {
00243   struct autoip *autoip = netif->autoip;
00244   err_t result = ERR_OK;
00245 
00246   if(netif_is_up(netif)) {
00247     netif_set_down(netif);
00248   }
00249 
00250   /* Set IP-Address, Netmask and Gateway to 0 to make sure that
00251    * ARP Packets are formed correctly
00252    */
00253   netif->ip_addr.addr = 0;
00254   netif->netmask.addr = 0;
00255   netif->gw.addr      = 0;
00256 
00257   LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE,
00258     ("autoip_start(netif=%p) %c%c%"U16_F"\n", (void*)netif, netif->name[0],
00259     netif->name[1], (u16_t)netif->num));
00260   if(autoip == NULL) {
00261     /* no AutoIP client attached yet? */
00262     LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE,
00263       ("autoip_start(): starting new AUTOIP client\n"));
00264     autoip = (struct autoip *)mem_malloc(sizeof(struct autoip)); // static_cast<struct autoip *>(x)
00265     if(autoip == NULL) {
00266       LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE,
00267         ("autoip_start(): could not allocate autoip\n"));
00268       return ERR_MEM;
00269     }
00270     memset( autoip, 0, sizeof(struct autoip));
00271     /* store this AutoIP client in the netif */
00272     netif->autoip = autoip;
00273     LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE, ("autoip_start(): allocated autoip"));
00274   } else {
00275     autoip->state = AUTOIP_STATE_OFF;
00276     autoip->ttw = 0;
00277     autoip->sent_num = 0;
00278     memset(&autoip->llipaddr, 0, sizeof(struct ip_addr));
00279     autoip->lastconflict = 0;
00280   }
00281 
00282   autoip_create_addr(netif, &(autoip->llipaddr));
00283   autoip->tried_llipaddr++;
00284   autoip->state = AUTOIP_STATE_PROBING;
00285   autoip->sent_num = 0;
00286 
00287   /* time to wait to first probe, this is randomly
00288    * choosen out of 0 to PROBE_WAIT seconds.
00289    * compliant to RFC 3927 Section 2.2.1
00290    */
00291   autoip->ttw = (u16_t)(LWIP_AUTOIP_RAND(netif) % (PROBE_WAIT * AUTOIP_TICKS_PER_SECOND));
00292 
00293   /*
00294    * if we tried more then MAX_CONFLICTS we must limit our rate for
00295    * accquiring and probing address
00296    * compliant to RFC 3927 Section 2.2.1
00297    */
00298 
00299   if(autoip->tried_llipaddr > MAX_CONFLICTS) {
00300     autoip->ttw = RATE_LIMIT_INTERVAL * AUTOIP_TICKS_PER_SECOND;
00301   }
00302 
00303   return result;
00304 }
00305 
00306 /**
00307  * Stop AutoIP client
00308  *
00309  * @param netif network interface on which stop the AutoIP client
00310  */
00311 err_t
00312 autoip_stop(struct netif *netif)
00313 {
00314   netif->autoip->state = AUTOIP_STATE_OFF;
00315   netif_set_down(netif);
00316   return ERR_OK;
00317 }
00318 
00319 /**
00320  * Has to be called in loop every AUTOIP_TMR_INTERVAL milliseconds
00321  */
00322 void
00323 autoip_tmr()
00324 {
00325   struct netif *netif = netif_list;
00326   /* loop through netif's */
00327   while (netif != NULL) {
00328     /* only act on AutoIP configured interfaces */
00329     if (netif->autoip != NULL) {
00330       if(netif->autoip->lastconflict > 0) {
00331         netif->autoip->lastconflict--;
00332       }
00333 
00334       LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE,
00335         ("autoip_tmr() AutoIP-State: %"U16_F", ttw=%"U16_F"\n",
00336         (u16_t)(netif->autoip->state), netif->autoip->ttw));
00337 
00338       switch(netif->autoip->state) {
00339         case AUTOIP_STATE_PROBING:
00340           if(netif->autoip->ttw > 0) {
00341             netif->autoip->ttw--;
00342           } else {
00343             if(netif->autoip->sent_num == PROBE_NUM) {
00344               netif->autoip->state = AUTOIP_STATE_ANNOUNCING;
00345               netif->autoip->sent_num = 0;
00346               netif->autoip->ttw = ANNOUNCE_WAIT * AUTOIP_TICKS_PER_SECOND;
00347             } else {
00348               etharp_request(netif, &(netif->autoip->llipaddr));
00349               LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE | 3,
00350                 ("autoip_tmr() PROBING Sent Probe\n"));
00351               netif->autoip->sent_num++;
00352               /* calculate time to wait to next probe */
00353               netif->autoip->ttw = (u16_t)((LWIP_AUTOIP_RAND(netif) %
00354                 ((PROBE_MAX - PROBE_MIN) * AUTOIP_TICKS_PER_SECOND) ) +
00355                 PROBE_MIN * AUTOIP_TICKS_PER_SECOND);
00356             }
00357           }
00358           break;
00359 
00360         case AUTOIP_STATE_ANNOUNCING:
00361           if(netif->autoip->ttw > 0) {
00362             netif->autoip->ttw--;
00363           } else {
00364             if(netif->autoip->sent_num == 0) {
00365              /* We are here the first time, so we waited ANNOUNCE_WAIT seconds
00366               * Now we can bind to an IP address and use it
00367               */
00368               autoip_bind(netif);
00369             }
00370 
00371             if(netif->autoip->sent_num == ANNOUNCE_NUM) {
00372               netif->autoip->state = AUTOIP_STATE_BOUND;
00373               netif->autoip->sent_num = 0;
00374               netif->autoip->ttw = 0;
00375             } else {
00376               autoip_arp_announce(netif);
00377               LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE | 3,
00378                 ("autoip_tmr() ANNOUNCING Sent Announce\n"));
00379               netif->autoip->sent_num++;
00380               netif->autoip->ttw = ANNOUNCE_INTERVAL * AUTOIP_TICKS_PER_SECOND;
00381             }
00382           }
00383           break;
00384       }
00385     }
00386     /* proceed to next network interface */
00387     netif = netif->next;
00388   }
00389 }
00390 
00391 /**
00392  * Handles every incoming ARP Packet, called by etharp_arp_input.
00393  *
00394  * @param netif network interface to use for autoip processing
00395  * @param hdr Incoming ARP packet
00396  */
00397 void
00398 autoip_arp_reply(struct netif *netif, struct etharp_hdr *hdr)
00399 {
00400   LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE | 3, ("autoip_arp_reply()\n"));
00401   if ((netif->autoip != NULL) && (netif->autoip->state != AUTOIP_STATE_OFF)) {
00402    /* when ip.src == llipaddr && hw.src != netif->hwaddr
00403     *
00404     * when probing  ip.dst == llipaddr && hw.src != netif->hwaddr
00405     * we have a conflict and must solve it
00406     */
00407     struct ip_addr sipaddr, dipaddr;
00408     struct eth_addr netifaddr;
00409     netifaddr.addr[0] = netif->hwaddr[0];
00410     netifaddr.addr[1] = netif->hwaddr[1];
00411     netifaddr.addr[2] = netif->hwaddr[2];
00412     netifaddr.addr[3] = netif->hwaddr[3];
00413     netifaddr.addr[4] = netif->hwaddr[4];
00414     netifaddr.addr[5] = netif->hwaddr[5];
00415 
00416     /* Copy struct ip_addr2 to aligned ip_addr, to support compilers without
00417      * structure packing (not using structure copy which breaks strict-aliasing rules).
00418      */
00419     SMEMCPY(&sipaddr, &hdr->sipaddr, sizeof(sipaddr));
00420     SMEMCPY(&dipaddr, &hdr->dipaddr, sizeof(dipaddr));
00421       
00422     if ((netif->autoip->state == AUTOIP_STATE_PROBING) ||
00423         ((netif->autoip->state == AUTOIP_STATE_ANNOUNCING) &&
00424          (netif->autoip->sent_num == 0))) {
00425      /* RFC 3927 Section 2.2.1:
00426       * from beginning to after ANNOUNCE_WAIT
00427       * seconds we have a conflict if
00428       * ip.src == llipaddr OR
00429       * ip.dst == llipaddr && hw.src != own hwaddr
00430       */
00431       if ((ip_addr_cmp(&sipaddr, &netif->autoip->llipaddr)) ||
00432           (ip_addr_cmp(&dipaddr, &netif->autoip->llipaddr) &&
00433            !eth_addr_cmp(&netifaddr, &hdr->shwaddr))) {
00434         LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE | 1,
00435           ("autoip_arp_reply(): Probe Conflict detected\n"));
00436         autoip_start(netif);
00437       }
00438     } else {
00439      /* RFC 3927 Section 2.5:
00440       * in any state we have a conflict if
00441       * ip.src == llipaddr && hw.src != own hwaddr
00442       */
00443       if (ip_addr_cmp(&sipaddr, &netif->autoip->llipaddr) &&
00444           !eth_addr_cmp(&netifaddr, &hdr->shwaddr)) {
00445         LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE | 1,
00446           ("autoip_arp_reply(): Conflicting ARP-Packet detected\n"));
00447         autoip_handle_arp_conflict(netif);
00448       }
00449     }
00450   }
00451 }
00452 
00453 #endif /* LWIP_AUTOIP */