rarp.c revision 1.18
1 /* $NetBSD: rarp.c,v 1.18 1999/11/12 13:12:09 lukem 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 #include "stand.h" 50 #include "net.h" 51 #include "netif.h" 52 53 54 /* 55 * Ethernet Address Resolution Protocol. 56 * 57 * See RFC 826 for protocol description. Structure below is adapted 58 * to resolving internet addresses. Field names used correspond to 59 * RFC 826. 60 */ 61 struct ether_arp { 62 struct arphdr ea_hdr; /* fixed-size header */ 63 u_int8_t arp_sha[ETHER_ADDR_LEN]; /* sender hardware address */ 64 u_int8_t arp_spa[4]; /* sender protocol address */ 65 u_int8_t arp_tha[ETHER_ADDR_LEN]; /* target hardware address */ 66 u_int8_t arp_tpa[4]; /* target protocol address */ 67 }; 68 #define arp_hrd ea_hdr.ar_hrd 69 #define arp_pro ea_hdr.ar_pro 70 #define arp_hln ea_hdr.ar_hln 71 #define arp_pln ea_hdr.ar_pln 72 #define arp_op ea_hdr.ar_op 73 74 static ssize_t rarpsend __P((struct iodesc *, void *, size_t)); 75 static ssize_t rarprecv __P((struct iodesc *, void *, size_t, time_t)); 76 77 /* 78 * Ethernet (Reverse) Address Resolution Protocol (see RFC 903, and 826). 79 */ 80 int 81 rarp_getipaddress(sock) 82 int sock; 83 { 84 struct iodesc *d; 85 register struct ether_arp *ap; 86 struct { 87 u_char header[ETHER_SIZE]; 88 struct { 89 struct ether_arp arp; 90 u_char pad[18]; /* 60 - sizeof(arp) */ 91 } data; 92 } wbuf; 93 struct { 94 u_char header[ETHER_SIZE]; 95 struct { 96 struct ether_arp arp; 97 u_char pad[24]; /* extra space */ 98 } data; 99 } rbuf; 100 101 #ifdef RARP_DEBUG 102 if (debug) 103 printf("rarp: socket=%d\n", sock); 104 #endif 105 if (!(d = socktodesc(sock))) { 106 printf("rarp: bad socket. %d\n", sock); 107 return (-1); 108 } 109 #ifdef RARP_DEBUG 110 if (debug) 111 printf("rarp: d=%lx\n", (u_long)d); 112 #endif 113 114 bzero((char*)&wbuf.data, sizeof(wbuf.data)); 115 ap = &wbuf.data.arp; 116 ap->arp_hrd = htons(ARPHRD_ETHER); 117 ap->arp_pro = htons(ETHERTYPE_IP); 118 ap->arp_hln = sizeof(ap->arp_sha); /* hardware address length */ 119 ap->arp_pln = sizeof(ap->arp_spa); /* protocol address length */ 120 ap->arp_op = htons(ARPOP_REVREQUEST); 121 bcopy(d->myea, ap->arp_sha, 6); 122 bcopy(d->myea, ap->arp_tha, 6); 123 124 if (sendrecv(d, 125 rarpsend, &wbuf.data, sizeof(wbuf.data), 126 rarprecv, &rbuf.data, sizeof(rbuf.data)) < 0) 127 { 128 printf("No response for RARP request\n"); 129 return (-1); 130 } 131 132 ap = &rbuf.data.arp; 133 bcopy(ap->arp_tpa, (char *)&myip, sizeof(myip)); 134 #if 0 135 /* XXX - Can NOT assume this is our root server! */ 136 bcopy(ap->arp_spa, (char *)&rootip, sizeof(rootip)); 137 #endif 138 139 /* Compute our "natural" netmask. */ 140 if (IN_CLASSA(myip.s_addr)) 141 netmask = IN_CLASSA_NET; 142 else if (IN_CLASSB(myip.s_addr)) 143 netmask = IN_CLASSB_NET; 144 else 145 netmask = IN_CLASSC_NET; 146 147 d->myip = myip; 148 return (0); 149 } 150 151 /* 152 * Broadcast a RARP request (i.e. who knows who I am) 153 */ 154 static ssize_t 155 rarpsend(d, pkt, len) 156 register struct iodesc *d; 157 register void *pkt; 158 register size_t len; 159 { 160 161 #ifdef RARP_DEBUG 162 if (debug) 163 printf("rarpsend: called\n"); 164 #endif 165 166 return (sendether(d, pkt, len, bcea, ETHERTYPE_REVARP)); 167 } 168 169 /* 170 * Returns 0 if this is the packet we're waiting for 171 * else -1 (and errno == 0) 172 */ 173 static ssize_t 174 rarprecv(d, pkt, len, tleft) 175 register struct iodesc *d; 176 register void *pkt; 177 register size_t len; 178 time_t tleft; 179 { 180 register ssize_t n; 181 register struct ether_arp *ap; 182 u_int16_t etype; /* host order */ 183 184 #ifdef RARP_DEBUG 185 if (debug) 186 printf("rarprecv: "); 187 #endif 188 189 n = readether(d, pkt, len, tleft, &etype); 190 errno = 0; /* XXX */ 191 if (n == -1 || n < sizeof(struct ether_arp)) { 192 #ifdef RARP_DEBUG 193 if (debug) 194 printf("bad len=%d\n", n); 195 #endif 196 return (-1); 197 } 198 199 if (etype != ETHERTYPE_REVARP) { 200 #ifdef RARP_DEBUG 201 if (debug) 202 printf("bad type=0x%x\n", etype); 203 #endif 204 return (-1); 205 } 206 207 ap = (struct ether_arp *)pkt; 208 if (ap->arp_hrd != htons(ARPHRD_ETHER) || 209 ap->arp_pro != htons(ETHERTYPE_IP) || 210 ap->arp_hln != sizeof(ap->arp_sha) || 211 ap->arp_pln != sizeof(ap->arp_spa) ) 212 { 213 #ifdef RARP_DEBUG 214 if (debug) 215 printf("bad hrd/pro/hln/pln\n"); 216 #endif 217 return (-1); 218 } 219 220 if (ap->arp_op != htons(ARPOP_REVREPLY)) { 221 #ifdef RARP_DEBUG 222 if (debug) 223 printf("bad op=0x%x\n", ntohs(ap->arp_op)); 224 #endif 225 return (-1); 226 } 227 228 /* Is the reply for our Ethernet address? */ 229 if (bcmp(ap->arp_tha, d->myea, 6)) { 230 #ifdef RARP_DEBUG 231 if (debug) 232 printf("unwanted address\n"); 233 #endif 234 return (-1); 235 } 236 237 /* We have our answer. */ 238 #ifdef RARP_DEBUG 239 if (debug) 240 printf("got it\n"); 241 #endif 242 return (n); 243 } 244
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