rarp.c revision 1.19
1 /* $NetBSD: rarp.c,v 1.19 1999/11/13 21:17:57 thorpej Exp $ */ 2 3 /* 4 * Copyright (c) 1992 Regents of the University of California. 5 * All rights reserved. 6 * 7 * This software was developed by the Computer Systems Engineering group 8 * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and 9 * contributed to Berkeley. 10 * 11 * Redistribution and use in source and binary forms, with or without 12 * modification, are permitted provided that the following conditions 13 * are met: 14 * 1. Redistributions of source code must retain the above copyright 15 * notice, this list of conditions and the following disclaimer. 16 * 2. Redistributions in binary form must reproduce the above copyright 17 * notice, this list of conditions and the following disclaimer in the 18 * documentation and/or other materials provided with the distribution. 19 * 3. All advertising materials mentioning features or use of this software 20 * must display the following acknowledgement: 21 * This product includes software developed by the University of 22 * California, Lawrence Berkeley Laboratory and its contributors. 23 * 4. Neither the name of the University nor the names of its contributors 24 * may be used to endorse or promote products derived from this software 25 * without specific prior written permission. 26 * 27 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 28 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 29 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 30 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 31 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 32 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 33 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 34 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 35 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 36 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 37 * SUCH DAMAGE. 38 * 39 * @(#) Header: arp.c,v 1.5 93/07/15 05:52:26 leres Exp (LBL) 40 */ 41 #include <sys/param.h> 42 #include <sys/socket.h> 43 #include <net/if.h> 44 #include <net/if_ether.h> 45 #include <netinet/in.h> 46 47 #include <netinet/in_systm.h> 48 49 #ifdef _STANDALONE 50 #include <lib/libkern/libkern.h> 51 #else 52 #include <string.h> 53 #endif 54 55 #include "stand.h" 56 #include "net.h" 57 #include "netif.h" 58 59 60 /* 61 * Ethernet Address Resolution Protocol. 62 * 63 * See RFC 826 for protocol description. Structure below is adapted 64 * to resolving internet addresses. Field names used correspond to 65 * RFC 826. 66 */ 67 struct ether_arp { 68 struct arphdr ea_hdr; /* fixed-size header */ 69 u_int8_t arp_sha[ETHER_ADDR_LEN]; /* sender hardware address */ 70 u_int8_t arp_spa[4]; /* sender protocol address */ 71 u_int8_t arp_tha[ETHER_ADDR_LEN]; /* target hardware address */ 72 u_int8_t arp_tpa[4]; /* target protocol address */ 73 }; 74 #define arp_hrd ea_hdr.ar_hrd 75 #define arp_pro ea_hdr.ar_pro 76 #define arp_hln ea_hdr.ar_hln 77 #define arp_pln ea_hdr.ar_pln 78 #define arp_op ea_hdr.ar_op 79 80 static ssize_t rarpsend __P((struct iodesc *, void *, size_t)); 81 static ssize_t rarprecv __P((struct iodesc *, void *, size_t, time_t)); 82 83 /* 84 * Ethernet (Reverse) Address Resolution Protocol (see RFC 903, and 826). 85 */ 86 int 87 rarp_getipaddress(sock) 88 int sock; 89 { 90 struct iodesc *d; 91 register struct ether_arp *ap; 92 struct { 93 u_char header[ETHER_SIZE]; 94 struct { 95 struct ether_arp arp; 96 u_char pad[18]; /* 60 - sizeof(arp) */ 97 } data; 98 } wbuf; 99 struct { 100 u_char header[ETHER_SIZE]; 101 struct { 102 struct ether_arp arp; 103 u_char pad[24]; /* extra space */ 104 } data; 105 } rbuf; 106 107 #ifdef RARP_DEBUG 108 if (debug) 109 printf("rarp: socket=%d\n", sock); 110 #endif 111 if (!(d = socktodesc(sock))) { 112 printf("rarp: bad socket. %d\n", sock); 113 return (-1); 114 } 115 #ifdef RARP_DEBUG 116 if (debug) 117 printf("rarp: d=%lx\n", (u_long)d); 118 #endif 119 120 bzero((char*)&wbuf.data, sizeof(wbuf.data)); 121 ap = &wbuf.data.arp; 122 ap->arp_hrd = htons(ARPHRD_ETHER); 123 ap->arp_pro = htons(ETHERTYPE_IP); 124 ap->arp_hln = sizeof(ap->arp_sha); /* hardware address length */ 125 ap->arp_pln = sizeof(ap->arp_spa); /* protocol address length */ 126 ap->arp_op = htons(ARPOP_REVREQUEST); 127 bcopy(d->myea, ap->arp_sha, 6); 128 bcopy(d->myea, ap->arp_tha, 6); 129 130 if (sendrecv(d, 131 rarpsend, &wbuf.data, sizeof(wbuf.data), 132 rarprecv, &rbuf.data, sizeof(rbuf.data)) < 0) 133 { 134 printf("No response for RARP request\n"); 135 return (-1); 136 } 137 138 ap = &rbuf.data.arp; 139 bcopy(ap->arp_tpa, (char *)&myip, sizeof(myip)); 140 #if 0 141 /* XXX - Can NOT assume this is our root server! */ 142 bcopy(ap->arp_spa, (char *)&rootip, sizeof(rootip)); 143 #endif 144 145 /* Compute our "natural" netmask. */ 146 if (IN_CLASSA(myip.s_addr)) 147 netmask = IN_CLASSA_NET; 148 else if (IN_CLASSB(myip.s_addr)) 149 netmask = IN_CLASSB_NET; 150 else 151 netmask = IN_CLASSC_NET; 152 153 d->myip = myip; 154 return (0); 155 } 156 157 /* 158 * Broadcast a RARP request (i.e. who knows who I am) 159 */ 160 static ssize_t 161 rarpsend(d, pkt, len) 162 register struct iodesc *d; 163 register void *pkt; 164 register size_t len; 165 { 166 167 #ifdef RARP_DEBUG 168 if (debug) 169 printf("rarpsend: called\n"); 170 #endif 171 172 return (sendether(d, pkt, len, bcea, ETHERTYPE_REVARP)); 173 } 174 175 /* 176 * Returns 0 if this is the packet we're waiting for 177 * else -1 (and errno == 0) 178 */ 179 static ssize_t 180 rarprecv(d, pkt, len, tleft) 181 register struct iodesc *d; 182 register void *pkt; 183 register size_t len; 184 time_t tleft; 185 { 186 register ssize_t n; 187 register struct ether_arp *ap; 188 u_int16_t etype; /* host order */ 189 190 #ifdef RARP_DEBUG 191 if (debug) 192 printf("rarprecv: "); 193 #endif 194 195 n = readether(d, pkt, len, tleft, &etype); 196 errno = 0; /* XXX */ 197 if (n == -1 || n < sizeof(struct ether_arp)) { 198 #ifdef RARP_DEBUG 199 if (debug) 200 printf("bad len=%d\n", n); 201 #endif 202 return (-1); 203 } 204 205 if (etype != ETHERTYPE_REVARP) { 206 #ifdef RARP_DEBUG 207 if (debug) 208 printf("bad type=0x%x\n", etype); 209 #endif 210 return (-1); 211 } 212 213 ap = (struct ether_arp *)pkt; 214 if (ap->arp_hrd != htons(ARPHRD_ETHER) || 215 ap->arp_pro != htons(ETHERTYPE_IP) || 216 ap->arp_hln != sizeof(ap->arp_sha) || 217 ap->arp_pln != sizeof(ap->arp_spa) ) 218 { 219 #ifdef RARP_DEBUG 220 if (debug) 221 printf("bad hrd/pro/hln/pln\n"); 222 #endif 223 return (-1); 224 } 225 226 if (ap->arp_op != htons(ARPOP_REVREPLY)) { 227 #ifdef RARP_DEBUG 228 if (debug) 229 printf("bad op=0x%x\n", ntohs(ap->arp_op)); 230 #endif 231 return (-1); 232 } 233 234 /* Is the reply for our Ethernet address? */ 235 if (bcmp(ap->arp_tha, d->myea, 6)) { 236 #ifdef RARP_DEBUG 237 if (debug) 238 printf("unwanted address\n"); 239 #endif 240 return (-1); 241 } 242 243 /* We have our answer. */ 244 #ifdef RARP_DEBUG 245 if (debug) 246 printf("got it\n"); 247 #endif 248 return (n); 249 } 250
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