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 /* Pseudo random macro based on netif informations.
00080  * You could use "rand()" from the C Library if you define LWIP_AUTOIP_RAND in lwipopts.h */
00081 #ifndef LWIP_AUTOIP_RAND
00082 #define LWIP_AUTOIP_RAND(netif) ( (((u32_t)((netif->hwaddr[5]) & 0xff) << 24) | \
00083                                    ((u32_t)((netif->hwaddr[3]) & 0xff) << 16) | \
00084                                    ((u32_t)((netif->hwaddr[2]) & 0xff) << 8) | \
00085                                    ((u32_t)((netif->hwaddr[4]) & 0xff))) + \
00086                                    (netif->autoip?netif->autoip->tried_llipaddr:0))
00087 #endif /* LWIP_AUTOIP_RAND */
00088 
00089 /* static functions */
00090 static void autoip_handle_arp_conflict(struct netif *netif);
00091 
00092 /* creates random LL IP-Address for a network interface */
00093 static void autoip_create_rand_addr(struct netif *netif, struct ip_addr *RandomIPAddr);
00094 
00095 /* sends an ARP announce */
00096 static err_t autoip_arp_announce(struct netif *netif);
00097 
00098 /* configure interface for use with current LL IP-Address */
00099 static err_t autoip_bind(struct netif *netif);
00100 
00101 /**
00102  * Initialize this module
00103  */
00104 void
00105 autoip_init(void)
00106 {
00107   LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE | 3, ("autoip_init()\n"));
00108 }
00109 
00110 /**
00111  * Handle a IP address conflict after an ARP conflict detection
00112  */
00113 static void
00114 autoip_handle_arp_conflict(struct netif *netif)
00115 {
00116   /* Somehow detect if we are defending or retreating */
00117   unsigned char defend = 1; /* tbd */
00118 
00119   if(defend) {
00120     if(netif->autoip->lastconflict > 0) {
00121       /* retreat, there was a conflicting ARP in the last
00122        * DEFEND_INTERVAL seconds
00123        */
00124       LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE | 1,
00125         ("autoip_handle_arp_conflict(): we are defending, but in DEFEND_INTERVAL, retreating\n"));
00126 
00127       /* TODO: close all TCP sessions */
00128       autoip_start(netif);
00129     } else {
00130       LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE | 1,
00131         ("autoip_handle_arp_conflict(): we are defend, send ARP Announce\n"));
00132       autoip_arp_announce(netif);
00133       netif->autoip->lastconflict = DEFEND_INTERVAL * AUTOIP_TICKS_PER_SECOND;
00134     }
00135   } else {
00136     LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE | 1,
00137       ("autoip_handle_arp_conflict(): we do not defend, retreating\n"));
00138     /* TODO: close all TCP sessions */
00139     autoip_start(netif);
00140   }
00141 }
00142 
00143 /**
00144  * Create an IP-Address out of range 169.254.1.0 to 169.254.254.255
00145  *
00146  * @param netif network interface on which create the IP-Address
00147  * @param RandomIPAddr ip address to initialize
00148  */
00149 static void
00150 autoip_create_rand_addr(struct netif *netif, struct ip_addr *RandomIPAddr)
00151 {
00152   /* Here we create an IP-Address out of range 169.254.1.0 to 169.254.254.255
00153    * compliant to RFC 3927 Section 2.1
00154    * We have 254 * 256 possibilities
00155    */
00156   
00157   RandomIPAddr->addr = (0xA9FE0100 + ((u32_t)(((u8_t)(netif->hwaddr[4])) |
00158     ((u32_t)((u8_t)(netif->hwaddr[5]))) << 8)) + netif->autoip->tried_llipaddr);
00159 
00160   if (RandomIPAddr->addr>0xA9FEFEFF) {
00161     RandomIPAddr->addr = (0xA9FE0100 + (RandomIPAddr->addr-0xA9FEFEFF));
00162   }
00163   if (RandomIPAddr->addr<0xA9FE0100) {
00164     RandomIPAddr->addr = (0xA9FEFEFF - (0xA9FE0100-RandomIPAddr->addr));
00165   }
00166   RandomIPAddr->addr = htonl(RandomIPAddr->addr);
00167   
00168   LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE | 1,
00169     ("autoip_create_rand_addr(): tried_llipaddr=%"U16_F", 0x%08"X32_F"\n",
00170     (u16_t)(netif->autoip->tried_llipaddr), (u32_t)(RandomIPAddr->addr)));
00171 }
00172 
00173 /**
00174  * Sends an ARP announce from a network interface
00175  *
00176  * @param netif network interface used to send the announce
00177  */
00178 static err_t
00179 autoip_arp_announce(struct netif *netif)
00180 {
00181   return etharp_raw(netif, (struct eth_addr *)netif->hwaddr, &ethbroadcast,
00182     (struct eth_addr *)netif->hwaddr, &netif->autoip->llipaddr, &ethzero,
00183     &netif->autoip->llipaddr, ARP_REQUEST);
00184 }
00185 
00186 /**
00187  * Configure interface for use with current LL IP-Address
00188  *
00189  * @param netif network interface to configure with current LL IP-Address
00190  */
00191 static err_t
00192 autoip_bind(struct netif *netif)
00193 {
00194   struct autoip *autoip = netif->autoip;
00195   struct ip_addr sn_mask, gw_addr;
00196 
00197   LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE | 3,
00198     ("autoip_bind(netif=%p) %c%c%"U16_F" 0x%08"X32_F"\n",
00199     (void*)netif, netif->name[0], netif->name[1], (u16_t)netif->num, autoip->llipaddr.addr));
00200 
00201   IP4_ADDR(&sn_mask, 255, 255, 0, 0);
00202   IP4_ADDR(&gw_addr, 0, 0, 0, 0);
00203 
00204   netif_set_ipaddr(netif, &autoip->llipaddr);
00205   netif_set_netmask(netif, &sn_mask);
00206   netif_set_gw(netif, &gw_addr);  
00207 
00208   /* bring the interface up */
00209   netif_set_up(netif);
00210 
00211   return ERR_OK;
00212 }
00213 
00214 /**
00215  * Start AutoIP client
00216  *
00217  * @param netif network interface on which start the AutoIP client
00218  */
00219 err_t
00220 autoip_start(struct netif *netif)
00221 {
00222   struct autoip *autoip = netif->autoip;
00223   err_t result = ERR_OK;
00224 
00225   if(netif_is_up(netif)) {
00226     netif_set_down(netif);
00227   }
00228 
00229   /* Set IP-Address, Netmask and Gateway to 0 to make sure that
00230    * ARP Packets are formed correctly
00231    */
00232   netif->ip_addr.addr = 0;
00233   netif->netmask.addr = 0;
00234   netif->gw.addr      = 0;
00235 
00236   LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE,
00237     ("autoip_start(netif=%p) %c%c%"U16_F"\n", (void*)netif, netif->name[0],
00238     netif->name[1], (u16_t)netif->num));
00239   if(autoip == NULL) {
00240     /* no AutoIP client attached yet? */
00241     LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE,
00242       ("autoip_start(): starting new AUTOIP client\n"));
00243     autoip = (struct autoip *)mem_malloc(sizeof(struct autoip)); // XXX: static_cast<struct autoip *>(x)
00244     if(autoip == NULL) {
00245       LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE,
00246         ("autoip_start(): could not allocate autoip\n"));
00247       return ERR_MEM;
00248     }
00249     memset( autoip, 0, sizeof(struct autoip));
00250     /* store this AutoIP client in the netif */
00251     netif->autoip = autoip;
00252     LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE, ("autoip_start(): allocated autoip"));
00253   } else {
00254     autoip->state = AUTOIP_STATE_OFF;
00255     autoip->ttw = 0;
00256     autoip->sent_num = 0;
00257     memset(&autoip->llipaddr, 0, sizeof(struct ip_addr));
00258     autoip->lastconflict = 0;
00259   }
00260 
00261   autoip_create_rand_addr(netif, &(autoip->llipaddr));
00262   autoip->tried_llipaddr++;
00263   autoip->state = AUTOIP_STATE_PROBING;
00264   autoip->sent_num = 0;
00265 
00266   /* time to wait to first probe, this is randomly
00267    * choosen out of 0 to PROBE_WAIT seconds.
00268    * compliant to RFC 3927 Section 2.2.1
00269    */
00270   autoip->ttw = (u16_t)(LWIP_AUTOIP_RAND(netif) % (PROBE_WAIT * AUTOIP_TICKS_PER_SECOND));
00271 
00272   /*
00273    * if we tried more then MAX_CONFLICTS we must limit our rate for
00274    * accquiring and probing address
00275    * compliant to RFC 3927 Section 2.2.1
00276    */
00277 
00278   if(autoip->tried_llipaddr > MAX_CONFLICTS) {
00279     autoip->ttw = RATE_LIMIT_INTERVAL * AUTOIP_TICKS_PER_SECOND;
00280   }
00281 
00282   return result;
00283 }
00284 
00285 /**
00286  * Stop AutoIP client
00287  *
00288  * @param netif network interface on which stop the AutoIP client
00289  */
00290 err_t
00291 autoip_stop(struct netif *netif)
00292 {
00293   netif->autoip->state = AUTOIP_STATE_OFF;
00294   netif_set_down(netif);
00295   return ERR_OK;
00296 }
00297 
00298 /**
00299  * Has to be called in loop every AUTOIP_TMR_INTERVAL milliseconds
00300  */
00301 void
00302 autoip_tmr()
00303 {
00304   struct netif *netif = netif_list;
00305   /* loop through netif's */
00306   while (netif != NULL) {
00307     /* only act on AutoIP configured interfaces */
00308     if (netif->autoip != NULL) {
00309       if(netif->autoip->lastconflict > 0) {
00310         netif->autoip->lastconflict--;
00311       }
00312 
00313       LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE,
00314         ("autoip_tmr() AutoIP-State: %"U16_F", ttw=%"U16_F"\n",
00315         (u16_t)(netif->autoip->state), netif->autoip->ttw));
00316 
00317       switch(netif->autoip->state) {
00318         case AUTOIP_STATE_PROBING:
00319           if(netif->autoip->ttw > 0) {
00320             netif->autoip->ttw--;
00321           } else {
00322             if(netif->autoip->sent_num == PROBE_NUM) {
00323               netif->autoip->state = AUTOIP_STATE_ANNOUNCING;
00324               netif->autoip->sent_num = 0;
00325               netif->autoip->ttw = ANNOUNCE_WAIT * AUTOIP_TICKS_PER_SECOND;
00326             } else {
00327               etharp_request(netif, &(netif->autoip->llipaddr));
00328               LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE | 3,
00329                 ("autoip_tmr() PROBING Sent Probe\n"));
00330               netif->autoip->sent_num++;
00331               /* calculate time to wait to next probe */
00332               netif->autoip->ttw = (u16_t)((LWIP_AUTOIP_RAND(netif) %
00333                 ((PROBE_MAX - PROBE_MIN) * AUTOIP_TICKS_PER_SECOND) ) +
00334                 PROBE_MIN * AUTOIP_TICKS_PER_SECOND);
00335             }
00336           }
00337           break;
00338 
00339         case AUTOIP_STATE_ANNOUNCING:
00340           if(netif->autoip->ttw > 0) {
00341             netif->autoip->ttw--;
00342           } else {
00343             if(netif->autoip->sent_num == 0) {
00344              /* We are here the first time, so we waited ANNOUNCE_WAIT seconds
00345               * Now we can bind to an IP address and use it
00346               */
00347               autoip_bind(netif);
00348             }
00349 
00350             if(netif->autoip->sent_num == ANNOUNCE_NUM) {
00351               netif->autoip->state = AUTOIP_STATE_BOUND;
00352               netif->autoip->sent_num = 0;
00353               netif->autoip->ttw = 0;
00354             } else {
00355               autoip_arp_announce(netif);
00356               LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE | 3,
00357                 ("autoip_tmr() ANNOUNCING Sent Announce\n"));
00358               netif->autoip->sent_num++;
00359               netif->autoip->ttw = ANNOUNCE_INTERVAL * AUTOIP_TICKS_PER_SECOND;
00360             }
00361           }
00362           break;
00363       }
00364     }
00365     /* proceed to next network interface */
00366     netif = netif->next;
00367   }
00368 }
00369 
00370 /**
00371  * Handles every incoming ARP Packet, called by etharp_arp_input.
00372  *
00373  * @param netif network interface to use for autoip processing
00374  * @param hdr Incoming ARP packet
00375  */
00376 void
00377 autoip_arp_reply(struct netif *netif, struct etharp_hdr *hdr)
00378 {
00379   LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE | 3, ("autoip_arp_reply()\n"));
00380   if ((netif->autoip != NULL) && (netif->autoip->state != AUTOIP_STATE_OFF)) {
00381    /* when ip.src == llipaddr && hw.src != netif->hwaddr
00382     *
00383     * when probing  ip.dst == llipaddr && hw.src != netif->hwaddr
00384     * we have a conflict and must solve it
00385     */
00386     struct ip_addr sipaddr, dipaddr;
00387     struct eth_addr netifaddr;
00388     netifaddr.addr[0] = netif->hwaddr[0];
00389     netifaddr.addr[1] = netif->hwaddr[1];
00390     netifaddr.addr[2] = netif->hwaddr[2];
00391     netifaddr.addr[3] = netif->hwaddr[3];
00392     netifaddr.addr[4] = netif->hwaddr[4];
00393     netifaddr.addr[5] = netif->hwaddr[5];
00394 
00395     /* Copy struct ip_addr2 to aligned ip_addr, to support compilers without
00396      * structure packing (not using structure copy which breaks strict-aliasing rules).
00397      */
00398     MEMCPY(&sipaddr, &hdr->sipaddr, sizeof(sipaddr));
00399     MEMCPY(&dipaddr, &hdr->dipaddr, sizeof(dipaddr));
00400       
00401     if ((netif->autoip->state == AUTOIP_STATE_PROBING) ||
00402         ((netif->autoip->state == AUTOIP_STATE_ANNOUNCING) &&
00403          (netif->autoip->sent_num == 0))) {
00404      /* RFC 3927 Section 2.2.1:
00405       * from beginning to after ANNOUNCE_WAIT
00406       * seconds we have a conflict if
00407       * ip.src == llipaddr OR
00408       * ip.dst == llipaddr && hw.src != own hwaddr
00409       */
00410       if ((ip_addr_cmp(&sipaddr, &netif->autoip->llipaddr)) ||
00411           (ip_addr_cmp(&dipaddr, &netif->autoip->llipaddr) &&
00412            !eth_addr_cmp(&netifaddr, &hdr->shwaddr))) {
00413         LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE | 1,
00414           ("autoip_arp_reply(): Probe Conflict detected\n"));
00415         autoip_start(netif);
00416       }
00417     } else {
00418      /* RFC 3927 Section 2.5:
00419       * in any state we have a conflict if
00420       * ip.src == llipaddr && hw.src != own hwaddr
00421       */
00422       if (ip_addr_cmp(&sipaddr, &netif->autoip->llipaddr) &&
00423           !eth_addr_cmp(&netifaddr, &hdr->shwaddr)) {
00424         LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE | 1,
00425           ("autoip_arp_reply(): Conflicting ARP-Packet detected\n"));
00426         autoip_handle_arp_conflict(netif);
00427       }
00428     }
00429   }
00430 }
00431 
00432 #endif /* LWIP_AUTOIP */