1*4a5d661aSToomas Soome /* $NetBSD: arp.c,v 1.18 1997/07/07 15:52:49 drochner Exp $ */ 2*4a5d661aSToomas Soome 3*4a5d661aSToomas Soome /* 4*4a5d661aSToomas Soome * Copyright (c) 1992 Regents of the University of California. 5*4a5d661aSToomas Soome * All rights reserved. 6*4a5d661aSToomas Soome * 7*4a5d661aSToomas Soome * This software was developed by the Computer Systems Engineering group 8*4a5d661aSToomas Soome * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and 9*4a5d661aSToomas Soome * contributed to Berkeley. 10*4a5d661aSToomas Soome * 11*4a5d661aSToomas Soome * Redistribution and use in source and binary forms, with or without 12*4a5d661aSToomas Soome * modification, are permitted provided that the following conditions 13*4a5d661aSToomas Soome * are met: 14*4a5d661aSToomas Soome * 1. Redistributions of source code must retain the above copyright 15*4a5d661aSToomas Soome * notice, this list of conditions and the following disclaimer. 16*4a5d661aSToomas Soome * 2. Redistributions in binary form must reproduce the above copyright 17*4a5d661aSToomas Soome * notice, this list of conditions and the following disclaimer in the 18*4a5d661aSToomas Soome * documentation and/or other materials provided with the distribution. 19*4a5d661aSToomas Soome * 4. Neither the name of the University nor the names of its contributors 20*4a5d661aSToomas Soome * may be used to endorse or promote products derived from this software 21*4a5d661aSToomas Soome * without specific prior written permission. 22*4a5d661aSToomas Soome * 23*4a5d661aSToomas Soome * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 24*4a5d661aSToomas Soome * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25*4a5d661aSToomas Soome * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26*4a5d661aSToomas Soome * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 27*4a5d661aSToomas Soome * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28*4a5d661aSToomas Soome * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29*4a5d661aSToomas Soome * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30*4a5d661aSToomas Soome * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31*4a5d661aSToomas Soome * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32*4a5d661aSToomas Soome * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33*4a5d661aSToomas Soome * SUCH DAMAGE. 34*4a5d661aSToomas Soome * 35*4a5d661aSToomas Soome * @(#) Header: arp.c,v 1.5 93/07/15 05:52:26 leres Exp (LBL) 36*4a5d661aSToomas Soome */ 37*4a5d661aSToomas Soome 38*4a5d661aSToomas Soome #include <sys/cdefs.h> 39*4a5d661aSToomas Soome __FBSDID("$FreeBSD$"); 40*4a5d661aSToomas Soome 41*4a5d661aSToomas Soome #include <sys/types.h> 42*4a5d661aSToomas Soome #include <sys/socket.h> 43*4a5d661aSToomas Soome #include <net/if.h> 44*4a5d661aSToomas Soome #include <netinet/in.h> 45*4a5d661aSToomas Soome #include <netinet/if_ether.h> 46*4a5d661aSToomas Soome 47*4a5d661aSToomas Soome #include <netinet/in_systm.h> 48*4a5d661aSToomas Soome 49*4a5d661aSToomas Soome #include <string.h> 50*4a5d661aSToomas Soome 51*4a5d661aSToomas Soome #include "stand.h" 52*4a5d661aSToomas Soome #include "net.h" 53*4a5d661aSToomas Soome 54*4a5d661aSToomas Soome /* Cache stuff */ 55*4a5d661aSToomas Soome #define ARP_NUM 8 /* need at most 3 arp entries */ 56*4a5d661aSToomas Soome 57*4a5d661aSToomas Soome struct arp_list { 58*4a5d661aSToomas Soome struct in_addr addr; 59*4a5d661aSToomas Soome u_char ea[6]; 60*4a5d661aSToomas Soome } arp_list[ARP_NUM] = { 61*4a5d661aSToomas Soome /* XXX - net order `INADDR_BROADCAST' must be a constant */ 62*4a5d661aSToomas Soome { {0xffffffff}, BA } 63*4a5d661aSToomas Soome }; 64*4a5d661aSToomas Soome int arp_num = 1; 65*4a5d661aSToomas Soome 66*4a5d661aSToomas Soome /* Local forwards */ 67*4a5d661aSToomas Soome static ssize_t arpsend(struct iodesc *, void *, size_t); 68*4a5d661aSToomas Soome static ssize_t arprecv(struct iodesc *, void *, size_t, time_t); 69*4a5d661aSToomas Soome 70*4a5d661aSToomas Soome /* Broadcast an ARP packet, asking who has addr on interface d */ 71*4a5d661aSToomas Soome u_char * 72*4a5d661aSToomas Soome arpwhohas(d, addr) 73*4a5d661aSToomas Soome struct iodesc *d; 74*4a5d661aSToomas Soome struct in_addr addr; 75*4a5d661aSToomas Soome { 76*4a5d661aSToomas Soome int i; 77*4a5d661aSToomas Soome struct ether_arp *ah; 78*4a5d661aSToomas Soome struct arp_list *al; 79*4a5d661aSToomas Soome struct { 80*4a5d661aSToomas Soome struct ether_header eh; 81*4a5d661aSToomas Soome struct { 82*4a5d661aSToomas Soome struct ether_arp arp; 83*4a5d661aSToomas Soome u_char pad[18]; /* 60 - sizeof(...) */ 84*4a5d661aSToomas Soome } data; 85*4a5d661aSToomas Soome } wbuf; 86*4a5d661aSToomas Soome struct { 87*4a5d661aSToomas Soome struct ether_header eh; 88*4a5d661aSToomas Soome struct { 89*4a5d661aSToomas Soome struct ether_arp arp; 90*4a5d661aSToomas Soome u_char pad[24]; /* extra space */ 91*4a5d661aSToomas Soome } data; 92*4a5d661aSToomas Soome } rbuf; 93*4a5d661aSToomas Soome 94*4a5d661aSToomas Soome /* Try for cached answer first */ 95*4a5d661aSToomas Soome for (i = 0, al = arp_list; i < arp_num; ++i, ++al) 96*4a5d661aSToomas Soome if (addr.s_addr == al->addr.s_addr) 97*4a5d661aSToomas Soome return (al->ea); 98*4a5d661aSToomas Soome 99*4a5d661aSToomas Soome /* Don't overflow cache */ 100*4a5d661aSToomas Soome if (arp_num > ARP_NUM - 1) { 101*4a5d661aSToomas Soome arp_num = 1; /* recycle */ 102*4a5d661aSToomas Soome printf("arpwhohas: overflowed arp_list!\n"); 103*4a5d661aSToomas Soome } 104*4a5d661aSToomas Soome 105*4a5d661aSToomas Soome #ifdef ARP_DEBUG 106*4a5d661aSToomas Soome if (debug) 107*4a5d661aSToomas Soome printf("arpwhohas: send request for %s\n", inet_ntoa(addr)); 108*4a5d661aSToomas Soome #endif 109*4a5d661aSToomas Soome 110*4a5d661aSToomas Soome bzero((char*)&wbuf.data, sizeof(wbuf.data)); 111*4a5d661aSToomas Soome ah = &wbuf.data.arp; 112*4a5d661aSToomas Soome ah->arp_hrd = htons(ARPHRD_ETHER); 113*4a5d661aSToomas Soome ah->arp_pro = htons(ETHERTYPE_IP); 114*4a5d661aSToomas Soome ah->arp_hln = sizeof(ah->arp_sha); /* hardware address length */ 115*4a5d661aSToomas Soome ah->arp_pln = sizeof(ah->arp_spa); /* protocol address length */ 116*4a5d661aSToomas Soome ah->arp_op = htons(ARPOP_REQUEST); 117*4a5d661aSToomas Soome MACPY(d->myea, ah->arp_sha); 118*4a5d661aSToomas Soome bcopy(&d->myip, ah->arp_spa, sizeof(ah->arp_spa)); 119*4a5d661aSToomas Soome /* Leave zeros in arp_tha */ 120*4a5d661aSToomas Soome bcopy(&addr, ah->arp_tpa, sizeof(ah->arp_tpa)); 121*4a5d661aSToomas Soome 122*4a5d661aSToomas Soome /* Store ip address in cache (incomplete entry). */ 123*4a5d661aSToomas Soome al->addr = addr; 124*4a5d661aSToomas Soome 125*4a5d661aSToomas Soome i = sendrecv(d, 126*4a5d661aSToomas Soome arpsend, &wbuf.data, sizeof(wbuf.data), 127*4a5d661aSToomas Soome arprecv, &rbuf.data, sizeof(rbuf.data)); 128*4a5d661aSToomas Soome if (i == -1) { 129*4a5d661aSToomas Soome panic("arp: no response for %s\n", 130*4a5d661aSToomas Soome inet_ntoa(addr)); 131*4a5d661aSToomas Soome } 132*4a5d661aSToomas Soome 133*4a5d661aSToomas Soome /* Store ethernet address in cache */ 134*4a5d661aSToomas Soome ah = &rbuf.data.arp; 135*4a5d661aSToomas Soome #ifdef ARP_DEBUG 136*4a5d661aSToomas Soome if (debug) { 137*4a5d661aSToomas Soome printf("arp: response from %s\n", 138*4a5d661aSToomas Soome ether_sprintf(rbuf.eh.ether_shost)); 139*4a5d661aSToomas Soome printf("arp: cacheing %s --> %s\n", 140*4a5d661aSToomas Soome inet_ntoa(addr), ether_sprintf(ah->arp_sha)); 141*4a5d661aSToomas Soome } 142*4a5d661aSToomas Soome #endif 143*4a5d661aSToomas Soome MACPY(ah->arp_sha, al->ea); 144*4a5d661aSToomas Soome ++arp_num; 145*4a5d661aSToomas Soome 146*4a5d661aSToomas Soome return (al->ea); 147*4a5d661aSToomas Soome } 148*4a5d661aSToomas Soome 149*4a5d661aSToomas Soome static ssize_t 150*4a5d661aSToomas Soome arpsend(d, pkt, len) 151*4a5d661aSToomas Soome struct iodesc *d; 152*4a5d661aSToomas Soome void *pkt; 153*4a5d661aSToomas Soome size_t len; 154*4a5d661aSToomas Soome { 155*4a5d661aSToomas Soome 156*4a5d661aSToomas Soome #ifdef ARP_DEBUG 157*4a5d661aSToomas Soome if (debug) 158*4a5d661aSToomas Soome printf("arpsend: called\n"); 159*4a5d661aSToomas Soome #endif 160*4a5d661aSToomas Soome 161*4a5d661aSToomas Soome return (sendether(d, pkt, len, bcea, ETHERTYPE_ARP)); 162*4a5d661aSToomas Soome } 163*4a5d661aSToomas Soome 164*4a5d661aSToomas Soome /* 165*4a5d661aSToomas Soome * Returns 0 if this is the packet we're waiting for 166*4a5d661aSToomas Soome * else -1 (and errno == 0) 167*4a5d661aSToomas Soome */ 168*4a5d661aSToomas Soome static ssize_t 169*4a5d661aSToomas Soome arprecv(d, pkt, len, tleft) 170*4a5d661aSToomas Soome struct iodesc *d; 171*4a5d661aSToomas Soome void *pkt; 172*4a5d661aSToomas Soome size_t len; 173*4a5d661aSToomas Soome time_t tleft; 174*4a5d661aSToomas Soome { 175*4a5d661aSToomas Soome ssize_t n; 176*4a5d661aSToomas Soome struct ether_arp *ah; 177*4a5d661aSToomas Soome u_int16_t etype; /* host order */ 178*4a5d661aSToomas Soome 179*4a5d661aSToomas Soome #ifdef ARP_DEBUG 180*4a5d661aSToomas Soome if (debug) 181*4a5d661aSToomas Soome printf("arprecv: "); 182*4a5d661aSToomas Soome #endif 183*4a5d661aSToomas Soome 184*4a5d661aSToomas Soome n = readether(d, pkt, len, tleft, &etype); 185*4a5d661aSToomas Soome errno = 0; /* XXX */ 186*4a5d661aSToomas Soome if (n == -1 || n < sizeof(struct ether_arp)) { 187*4a5d661aSToomas Soome #ifdef ARP_DEBUG 188*4a5d661aSToomas Soome if (debug) 189*4a5d661aSToomas Soome printf("bad len=%d\n", n); 190*4a5d661aSToomas Soome #endif 191*4a5d661aSToomas Soome return (-1); 192*4a5d661aSToomas Soome } 193*4a5d661aSToomas Soome 194*4a5d661aSToomas Soome if (etype != ETHERTYPE_ARP) { 195*4a5d661aSToomas Soome #ifdef ARP_DEBUG 196*4a5d661aSToomas Soome if (debug) 197*4a5d661aSToomas Soome printf("not arp type=%d\n", etype); 198*4a5d661aSToomas Soome #endif 199*4a5d661aSToomas Soome return (-1); 200*4a5d661aSToomas Soome } 201*4a5d661aSToomas Soome 202*4a5d661aSToomas Soome /* Ethernet address now checked in readether() */ 203*4a5d661aSToomas Soome 204*4a5d661aSToomas Soome ah = (struct ether_arp *)pkt; 205*4a5d661aSToomas Soome if (ah->arp_hrd != htons(ARPHRD_ETHER) || 206*4a5d661aSToomas Soome ah->arp_pro != htons(ETHERTYPE_IP) || 207*4a5d661aSToomas Soome ah->arp_hln != sizeof(ah->arp_sha) || 208*4a5d661aSToomas Soome ah->arp_pln != sizeof(ah->arp_spa) ) 209*4a5d661aSToomas Soome { 210*4a5d661aSToomas Soome #ifdef ARP_DEBUG 211*4a5d661aSToomas Soome if (debug) 212*4a5d661aSToomas Soome printf("bad hrd/pro/hln/pln\n"); 213*4a5d661aSToomas Soome #endif 214*4a5d661aSToomas Soome return (-1); 215*4a5d661aSToomas Soome } 216*4a5d661aSToomas Soome 217*4a5d661aSToomas Soome if (ah->arp_op == htons(ARPOP_REQUEST)) { 218*4a5d661aSToomas Soome #ifdef ARP_DEBUG 219*4a5d661aSToomas Soome if (debug) 220*4a5d661aSToomas Soome printf("is request\n"); 221*4a5d661aSToomas Soome #endif 222*4a5d661aSToomas Soome arp_reply(d, ah); 223*4a5d661aSToomas Soome return (-1); 224*4a5d661aSToomas Soome } 225*4a5d661aSToomas Soome 226*4a5d661aSToomas Soome if (ah->arp_op != htons(ARPOP_REPLY)) { 227*4a5d661aSToomas Soome #ifdef ARP_DEBUG 228*4a5d661aSToomas Soome if (debug) 229*4a5d661aSToomas Soome printf("not ARP reply\n"); 230*4a5d661aSToomas Soome #endif 231*4a5d661aSToomas Soome return (-1); 232*4a5d661aSToomas Soome } 233*4a5d661aSToomas Soome 234*4a5d661aSToomas Soome /* Is the reply from the source we want? */ 235*4a5d661aSToomas Soome if (bcmp(&arp_list[arp_num].addr, 236*4a5d661aSToomas Soome ah->arp_spa, sizeof(ah->arp_spa))) 237*4a5d661aSToomas Soome { 238*4a5d661aSToomas Soome #ifdef ARP_DEBUG 239*4a5d661aSToomas Soome if (debug) 240*4a5d661aSToomas Soome printf("unwanted address\n"); 241*4a5d661aSToomas Soome #endif 242*4a5d661aSToomas Soome return (-1); 243*4a5d661aSToomas Soome } 244*4a5d661aSToomas Soome /* We don't care who the reply was sent to. */ 245*4a5d661aSToomas Soome 246*4a5d661aSToomas Soome /* We have our answer. */ 247*4a5d661aSToomas Soome #ifdef ARP_DEBUG 248*4a5d661aSToomas Soome if (debug) 249*4a5d661aSToomas Soome printf("got it\n"); 250*4a5d661aSToomas Soome #endif 251*4a5d661aSToomas Soome return (n); 252*4a5d661aSToomas Soome } 253*4a5d661aSToomas Soome 254*4a5d661aSToomas Soome /* 255*4a5d661aSToomas Soome * Convert an ARP request into a reply and send it. 256*4a5d661aSToomas Soome * Notes: Re-uses buffer. Pad to length = 46. 257*4a5d661aSToomas Soome */ 258*4a5d661aSToomas Soome void 259*4a5d661aSToomas Soome arp_reply(d, pkt) 260*4a5d661aSToomas Soome struct iodesc *d; 261*4a5d661aSToomas Soome void *pkt; /* the request */ 262*4a5d661aSToomas Soome { 263*4a5d661aSToomas Soome struct ether_arp *arp = pkt; 264*4a5d661aSToomas Soome 265*4a5d661aSToomas Soome if (arp->arp_hrd != htons(ARPHRD_ETHER) || 266*4a5d661aSToomas Soome arp->arp_pro != htons(ETHERTYPE_IP) || 267*4a5d661aSToomas Soome arp->arp_hln != sizeof(arp->arp_sha) || 268*4a5d661aSToomas Soome arp->arp_pln != sizeof(arp->arp_spa) ) 269*4a5d661aSToomas Soome { 270*4a5d661aSToomas Soome #ifdef ARP_DEBUG 271*4a5d661aSToomas Soome if (debug) 272*4a5d661aSToomas Soome printf("arp_reply: bad hrd/pro/hln/pln\n"); 273*4a5d661aSToomas Soome #endif 274*4a5d661aSToomas Soome return; 275*4a5d661aSToomas Soome } 276*4a5d661aSToomas Soome 277*4a5d661aSToomas Soome if (arp->arp_op != htons(ARPOP_REQUEST)) { 278*4a5d661aSToomas Soome #ifdef ARP_DEBUG 279*4a5d661aSToomas Soome if (debug) 280*4a5d661aSToomas Soome printf("arp_reply: not request!\n"); 281*4a5d661aSToomas Soome #endif 282*4a5d661aSToomas Soome return; 283*4a5d661aSToomas Soome } 284*4a5d661aSToomas Soome 285*4a5d661aSToomas Soome /* If we are not the target, ignore the request. */ 286*4a5d661aSToomas Soome if (bcmp(arp->arp_tpa, &d->myip, sizeof(arp->arp_tpa))) 287*4a5d661aSToomas Soome return; 288*4a5d661aSToomas Soome 289*4a5d661aSToomas Soome #ifdef ARP_DEBUG 290*4a5d661aSToomas Soome if (debug) { 291*4a5d661aSToomas Soome printf("arp_reply: to %s\n", ether_sprintf(arp->arp_sha)); 292*4a5d661aSToomas Soome } 293*4a5d661aSToomas Soome #endif 294*4a5d661aSToomas Soome 295*4a5d661aSToomas Soome arp->arp_op = htons(ARPOP_REPLY); 296*4a5d661aSToomas Soome /* source becomes target */ 297*4a5d661aSToomas Soome bcopy(arp->arp_sha, arp->arp_tha, sizeof(arp->arp_tha)); 298*4a5d661aSToomas Soome bcopy(arp->arp_spa, arp->arp_tpa, sizeof(arp->arp_tpa)); 299*4a5d661aSToomas Soome /* here becomes source */ 300*4a5d661aSToomas Soome bcopy(d->myea, arp->arp_sha, sizeof(arp->arp_sha)); 301*4a5d661aSToomas Soome bcopy(&d->myip, arp->arp_spa, sizeof(arp->arp_spa)); 302*4a5d661aSToomas Soome 303*4a5d661aSToomas Soome /* 304*4a5d661aSToomas Soome * No need to get fancy here. If the send fails, the 305*4a5d661aSToomas Soome * requestor will just ask again. 306*4a5d661aSToomas Soome */ 307*4a5d661aSToomas Soome (void) sendether(d, pkt, sizeof(*arp) + 18, 308*4a5d661aSToomas Soome arp->arp_tha, ETHERTYPE_ARP); 309*4a5d661aSToomas Soome } 310