rarp.c revision 1.32
1 /* $NetBSD: rarp.c,v 1.32 2014/03/29 14:30:16 jakllsch 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 58 59 /* 60 * Ethernet Address Resolution Protocol. 61 * 62 * See RFC 826 for protocol description. Structure below is adapted 63 * to resolving internet addresses. Field names used correspond to 64 * RFC 826. 65 */ 66 struct ether_arp { 67 struct arphdr ea_hdr; /* fixed-size header */ 68 u_int8_t arp_sha[ETHER_ADDR_LEN]; /* sender hardware address */ 69 u_int8_t arp_spa[4]; /* sender protocol address */ 70 u_int8_t arp_tha[ETHER_ADDR_LEN]; /* target hardware address */ 71 u_int8_t arp_tpa[4]; /* target protocol address */ 72 }; 73 #define arp_hrd ea_hdr.ar_hrd 74 #define arp_pro ea_hdr.ar_pro 75 #define arp_hln ea_hdr.ar_hln 76 #define arp_pln ea_hdr.ar_pln 77 #define arp_op ea_hdr.ar_op 78 79 static ssize_t rarpsend(struct iodesc *, void *, size_t); 80 static ssize_t rarprecv(struct iodesc *, void *, size_t, saseconds_t); 81 82 /* 83 * Ethernet (Reverse) Address Resolution Protocol (see RFC 903, and 826). 84 */ 85 int 86 rarp_getipaddress(int sock) 87 { 88 struct iodesc *d; 89 struct ether_arp *ap; 90 struct { 91 u_char header[ETHERNET_HEADER_SIZE]; 92 struct { 93 struct ether_arp arp; 94 u_char pad[18]; /* 60 - sizeof(arp) */ 95 } data; 96 } wbuf; 97 struct { 98 u_char header[ETHERNET_HEADER_SIZE]; 99 struct { 100 struct ether_arp arp; 101 u_char pad[24]; /* extra space */ 102 } data; 103 } rbuf; 104 105 #ifdef RARP_DEBUG 106 if (debug) 107 printf("rarp: socket=%d\n", sock); 108 #endif 109 if (!(d = socktodesc(sock))) { 110 printf("rarp: bad socket. %d\n", sock); 111 return -1; 112 } 113 #ifdef RARP_DEBUG 114 if (debug) 115 printf("rarp: d=%lx\n", (u_long)d); 116 #endif 117 118 (void)memset(&wbuf.data, 0, sizeof(wbuf.data)); 119 ap = &wbuf.data.arp; 120 ap->arp_hrd = htons(ARPHRD_ETHER); 121 ap->arp_pro = htons(ETHERTYPE_IP); 122 ap->arp_hln = sizeof(ap->arp_sha); /* hardware address length */ 123 ap->arp_pln = sizeof(ap->arp_spa); /* protocol address length */ 124 ap->arp_op = htons(ARPOP_REVREQUEST); 125 (void)memcpy(ap->arp_sha, d->myea, ETHER_ADDR_LEN); 126 (void)memcpy(ap->arp_tha, d->myea, ETHER_ADDR_LEN); 127 128 if (sendrecv(d, 129 rarpsend, &wbuf.data, sizeof(wbuf.data), 130 rarprecv, &rbuf.data, sizeof(rbuf.data)) < 0) 131 { 132 printf("No response for RARP request\n"); 133 return -1; 134 } 135 136 ap = &rbuf.data.arp; 137 (void)memcpy(&myip, ap->arp_tpa, sizeof(myip)); 138 #if 0 139 /* XXX - Can NOT assume this is our root server! */ 140 (void)memcpy(&rootip, ap->arp_spa, sizeof(rootip)); 141 #endif 142 143 /* Compute our "natural" netmask. */ 144 if (IN_CLASSA(myip.s_addr)) 145 netmask = IN_CLASSA_NET; 146 else if (IN_CLASSB(myip.s_addr)) 147 netmask = IN_CLASSB_NET; 148 else 149 netmask = IN_CLASSC_NET; 150 151 d->myip = myip; 152 return 0; 153 } 154 155 /* 156 * Broadcast a RARP request (i.e. who knows who I am) 157 */ 158 static ssize_t 159 rarpsend(struct iodesc *d, void *pkt, size_t len) 160 { 161 162 #ifdef RARP_DEBUG 163 if (debug) 164 printf("rarpsend: called\n"); 165 #endif 166 167 return sendether(d, pkt, len, bcea, ETHERTYPE_REVARP); 168 } 169 170 /* 171 * Returns 0 if this is the packet we're waiting for 172 * else -1 (and errno == 0) 173 */ 174 static ssize_t 175 rarprecv(struct iodesc *d, void *pkt, size_t len, saseconds_t tleft) 176 { 177 ssize_t n; 178 struct ether_arp *ap; 179 u_int16_t etype; /* host order */ 180 181 #ifdef RARP_DEBUG 182 if (debug) 183 printf("rarprecv: "); 184 #endif 185 186 n = readether(d, pkt, len, tleft, &etype); 187 errno = 0; /* XXX */ 188 if (n == -1 || (size_t)n < sizeof(struct ether_arp)) { 189 #ifdef RARP_DEBUG 190 if (debug) 191 printf("bad len=%d\n", (int)n); 192 #endif 193 return -1; 194 } 195 196 if (etype != ETHERTYPE_REVARP) { 197 #ifdef RARP_DEBUG 198 if (debug) 199 printf("bad type=0x%x\n", etype); 200 #endif 201 return -1; 202 } 203 204 ap = (struct ether_arp *)pkt; 205 if (ap->arp_hrd != htons(ARPHRD_ETHER) || 206 ap->arp_pro != htons(ETHERTYPE_IP) || 207 ap->arp_hln != sizeof(ap->arp_sha) || 208 ap->arp_pln != sizeof(ap->arp_spa) ) 209 { 210 #ifdef RARP_DEBUG 211 if (debug) 212 printf("bad hrd/pro/hln/pln\n"); 213 #endif 214 return -1; 215 } 216 217 if (ap->arp_op != htons(ARPOP_REVREPLY)) { 218 #ifdef RARP_DEBUG 219 if (debug) 220 printf("bad op=0x%x\n", ntohs(ap->arp_op)); 221 #endif 222 return -1; 223 } 224 225 /* Is the reply for our Ethernet address? */ 226 if (memcmp(ap->arp_tha, d->myea, ETHER_ADDR_LEN)) { 227 #ifdef RARP_DEBUG 228 if (debug) 229 printf("unwanted address\n"); 230 #endif 231 return -1; 232 } 233 234 /* We have our answer. */ 235 #ifdef RARP_DEBUG 236 if (debug) 237 printf("got it\n"); 238 #endif 239 return n; 240 } 241
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