bpf.c revision 31386
1/* 2 * Copyright (c) 1988, 1992 The University of Utah and the Center 3 * for Software Science (CSS). 4 * Copyright (c) 1992, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * This code is derived from software contributed to Berkeley by 8 * the Center for Software Science of the University of Utah Computer 9 * Science Department. CSS requests users of this software to return 10 * to css-dist@cs.utah.edu any improvements that they make and grant 11 * CSS redistribution rights. 12 * 13 * Redistribution and use in source and binary forms, with or without 14 * modification, are permitted provided that the following conditions 15 * are met: 16 * 1. Redistributions of source code must retain the above copyright 17 * notice, this list of conditions and the following disclaimer. 18 * 2. Redistributions in binary form must reproduce the above copyright 19 * notice, this list of conditions and the following disclaimer in the 20 * documentation and/or other materials provided with the distribution. 21 * 3. All advertising materials mentioning features or use of this software 22 * must display the following acknowledgement: 23 * This product includes software developed by the University of 24 * California, Berkeley and its contributors. 25 * 4. Neither the name of the University nor the names of its contributors 26 * may be used to endorse or promote products derived from this software 27 * without specific prior written permission. 28 * 29 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 30 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 31 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 32 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 33 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 34 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 35 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 36 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 37 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 38 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 39 * SUCH DAMAGE. 40 * 41 * from: @(#)bpf.c 8.1 (Berkeley) 6/4/93 42 * 43 * From: Utah Hdr: bpf.c 3.1 92/07/06 44 * Author: Jeff Forys, University of Utah CSS 45 */ 46 47#ifndef lint 48#if 0 49static const char sccsid[] = "@(#)bpf.c 8.1 (Berkeley) 6/4/93"; 50#endif 51static const char rcsid[] = 52 "$Id$"; 53#endif /* not lint */ 54 55#include <sys/param.h> 56#include <sys/ioctl.h> 57#include <sys/socket.h> 58#include <sys/time.h> 59 60#include <net/if.h> 61#include <net/bpf.h> 62 63#include <ctype.h> 64#include <errno.h> 65#include <fcntl.h> 66#include <stdio.h> 67#include <stdlib.h> 68#include <string.h> 69#include <syslog.h> 70#include <unistd.h> 71#include "defs.h" 72#include "pathnames.h" 73 74static int BpfFd = -1; 75static unsigned BpfLen = 0; 76static u_int8_t *BpfPkt = NULL; 77 78/* 79** BpfOpen -- Open and initialize a BPF device. 80** 81** Parameters: 82** None. 83** 84** Returns: 85** File descriptor of opened BPF device (for select() etc). 86** 87** Side Effects: 88** If an error is encountered, the program terminates here. 89*/ 90int 91BpfOpen() 92{ 93 struct ifreq ifr; 94 char bpfdev[32]; 95 int n = 0; 96 97 /* 98 * Open the first available BPF device. 99 */ 100 do { 101 (void) sprintf(bpfdev, _PATH_BPF, n++); 102 BpfFd = open(bpfdev, O_RDWR); 103 } while (BpfFd < 0 && (errno == EBUSY || errno == EPERM)); 104 105 if (BpfFd < 0) { 106 syslog(LOG_ERR, "bpf: no available devices: %m"); 107 Exit(0); 108 } 109 110 /* 111 * Set interface name for bpf device, get data link layer 112 * type and make sure it's type Ethernet. 113 */ 114 (void) strncpy(ifr.ifr_name, IntfName, sizeof(ifr.ifr_name)); 115 if (ioctl(BpfFd, BIOCSETIF, (caddr_t)&ifr) < 0) { 116 syslog(LOG_ERR, "bpf: ioctl(BIOCSETIF,%s): %m", IntfName); 117 Exit(0); 118 } 119 120 /* 121 * Make sure we are dealing with an Ethernet device. 122 */ 123 if (ioctl(BpfFd, BIOCGDLT, (caddr_t)&n) < 0) { 124 syslog(LOG_ERR, "bpf: ioctl(BIOCGDLT): %m"); 125 Exit(0); 126 } 127 if (n != DLT_EN10MB) { 128 syslog(LOG_ERR,"bpf: %s: data-link type %d unsupported", 129 IntfName, n); 130 Exit(0); 131 } 132 133 /* 134 * On read(), return packets immediately (do not buffer them). 135 */ 136 n = 1; 137 if (ioctl(BpfFd, BIOCIMMEDIATE, (caddr_t)&n) < 0) { 138 syslog(LOG_ERR, "bpf: ioctl(BIOCIMMEDIATE): %m"); 139 Exit(0); 140 } 141 142 /* 143 * Try to enable the chip/driver's multicast address filter to 144 * grab our RMP address. If this fails, try promiscuous mode. 145 * If this fails, there's no way we are going to get any RMP 146 * packets so just exit here. 147 */ 148#ifdef MSG_EOR 149 ifr.ifr_addr.sa_len = RMP_ADDRLEN + 2; 150#endif 151 ifr.ifr_addr.sa_family = AF_UNSPEC; 152 memmove((char *)&ifr.ifr_addr.sa_data[0], &RmpMcastAddr[0], RMP_ADDRLEN); 153 if (ioctl(BpfFd, BIOCPROMISC, (caddr_t)0) < 0) { 154 syslog(LOG_ERR, "bpf: can't set promiscuous mode: %m"); 155 Exit(0); 156 } 157 158 /* 159 * Ask BPF how much buffer space it requires and allocate one. 160 */ 161 if (ioctl(BpfFd, BIOCGBLEN, (caddr_t)&BpfLen) < 0) { 162 syslog(LOG_ERR, "bpf: ioctl(BIOCGBLEN): %m"); 163 Exit(0); 164 } 165 if (BpfPkt == NULL) 166 BpfPkt = (u_int8_t *)malloc(BpfLen); 167 168 if (BpfPkt == NULL) { 169 syslog(LOG_ERR, "bpf: out of memory (%u bytes for bpfpkt)", 170 BpfLen); 171 Exit(0); 172 } 173 174 /* 175 * Write a little program to snarf RMP Boot packets and stuff 176 * it down BPF's throat (i.e. set up the packet filter). 177 */ 178 { 179#define RMP ((struct rmp_packet *)0) 180 static struct bpf_insn bpf_insn[] = { 181 { BPF_LD|BPF_B|BPF_ABS, 0, 0, (long)&RMP->hp_llc.dsap }, 182 { BPF_JMP|BPF_JEQ|BPF_K, 0, 5, IEEE_DSAP_HP }, 183 { BPF_LD|BPF_H|BPF_ABS, 0, 0, (long)&RMP->hp_llc.cntrl }, 184 { BPF_JMP|BPF_JEQ|BPF_K, 0, 3, IEEE_CNTL_HP }, 185 { BPF_LD|BPF_H|BPF_ABS, 0, 0, (long)&RMP->hp_llc.dxsap }, 186 { BPF_JMP|BPF_JEQ|BPF_K, 0, 1, HPEXT_DXSAP }, 187 { BPF_RET|BPF_K, 0, 0, RMP_MAX_PACKET }, 188 { BPF_RET|BPF_K, 0, 0, 0x0 } 189 }; 190#undef RMP 191 static struct bpf_program bpf_pgm = { 192 sizeof(bpf_insn)/sizeof(bpf_insn[0]), bpf_insn 193 }; 194 195 if (ioctl(BpfFd, BIOCSETF, (caddr_t)&bpf_pgm) < 0) { 196 syslog(LOG_ERR, "bpf: ioctl(BIOCSETF): %m"); 197 Exit(0); 198 } 199 } 200 201 return(BpfFd); 202} 203 204/* 205** BPF GetIntfName -- Return the name of a network interface attached to 206** the system, or 0 if none can be found. The interface 207** must be configured up; the lowest unit number is 208** preferred; loopback is ignored. 209** 210** Parameters: 211** errmsg - if no network interface found, *errmsg explains why. 212** 213** Returns: 214** A (static) pointer to interface name, or NULL on error. 215** 216** Side Effects: 217** None. 218*/ 219char * 220BpfGetIntfName(errmsg) 221 char **errmsg; 222{ 223 struct ifreq ibuf[8], *ifrp, *ifend, *mp; 224 struct ifconf ifc; 225 int fd; 226 int minunit, n; 227 char *cp; 228 static char device[sizeof(ifrp->ifr_name)]; 229 static char errbuf[128] = "No Error!"; 230 231 if (errmsg != NULL) 232 *errmsg = errbuf; 233 234 if ((fd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) { 235 (void) strcpy(errbuf, "bpf: socket: %m"); 236 return(NULL); 237 } 238 ifc.ifc_len = sizeof ibuf; 239 ifc.ifc_buf = (caddr_t)ibuf; 240 241#ifdef OSIOCGIFCONF 242 if (ioctl(fd, OSIOCGIFCONF, (char *)&ifc) < 0 || 243 ifc.ifc_len < sizeof(struct ifreq)) { 244 (void) strcpy(errbuf, "bpf: ioctl(OSIOCGIFCONF): %m"); 245 return(NULL); 246 } 247#else 248 if (ioctl(fd, SIOCGIFCONF, (char *)&ifc) < 0 || 249 ifc.ifc_len < sizeof(struct ifreq)) { 250 (void) strcpy(errbuf, "bpf: ioctl(SIOCGIFCONF): %m"); 251 return(NULL); 252 } 253#endif 254 ifrp = ibuf; 255 ifend = (struct ifreq *)((char *)ibuf + ifc.ifc_len); 256 257 mp = 0; 258 minunit = 666; 259 for (; ifrp < ifend; ++ifrp) { 260 if (ioctl(fd, SIOCGIFFLAGS, (char *)ifrp) < 0) { 261 (void) strcpy(errbuf, "bpf: ioctl(SIOCGIFFLAGS): %m"); 262 return(NULL); 263 } 264 265 /* 266 * If interface is down or this is the loopback interface, 267 * ignore it. 268 */ 269 if ((ifrp->ifr_flags & IFF_UP) == 0 || 270#ifdef IFF_LOOPBACK 271 (ifrp->ifr_flags & IFF_LOOPBACK)) 272#else 273 (strcmp(ifrp->ifr_name, "lo0") == 0)) 274#endif 275 continue; 276 277 for (cp = ifrp->ifr_name; !isdigit(*cp); ++cp) 278 ; 279 n = atoi(cp); 280 if (n < minunit) { 281 minunit = n; 282 mp = ifrp; 283 } 284 } 285 286 (void) close(fd); 287 if (mp == 0) { 288 (void) strcpy(errbuf, "bpf: no interfaces found"); 289 return(NULL); 290 } 291 292 (void) strcpy(device, mp->ifr_name); 293 return(device); 294} 295 296/* 297** BpfRead -- Read packets from a BPF device and fill in `rconn'. 298** 299** Parameters: 300** rconn - filled in with next packet. 301** doread - is True if we can issue a read() syscall. 302** 303** Returns: 304** True if `rconn' contains a new packet, False otherwise. 305** 306** Side Effects: 307** None. 308*/ 309int 310BpfRead(rconn, doread) 311 RMPCONN *rconn; 312 int doread; 313{ 314 int datlen, caplen, hdrlen; 315 static u_int8_t *bp = NULL, *ep = NULL; 316 int cc; 317 318 /* 319 * The read() may block, or it may return one or more packets. 320 * We let the caller decide whether or not we can issue a read(). 321 */ 322 if (doread) { 323 if ((cc = read(BpfFd, (char *)BpfPkt, (int)BpfLen)) < 0) { 324 syslog(LOG_ERR, "bpf: read: %m"); 325 return(0); 326 } else { 327 bp = BpfPkt; 328 ep = BpfPkt + cc; 329 } 330 } 331 332#define bhp ((struct bpf_hdr *)bp) 333 /* 334 * If there is a new packet in the buffer, stuff it into `rconn' 335 * and return a success indication. 336 */ 337 if (bp < ep) { 338 datlen = bhp->bh_datalen; 339 caplen = bhp->bh_caplen; 340 hdrlen = bhp->bh_hdrlen; 341 342 if (caplen != datlen) 343 syslog(LOG_ERR, 344 "bpf: short packet dropped (%d of %d bytes)", 345 caplen, datlen); 346 else if (caplen > sizeof(struct rmp_packet)) 347 syslog(LOG_ERR, "bpf: large packet dropped (%d bytes)", 348 caplen); 349 else { 350 rconn->rmplen = caplen; 351 memmove((char *)&rconn->tstamp, (char *)&bhp->bh_tstamp, 352 sizeof(struct timeval)); 353 memmove((char *)&rconn->rmp, (char *)bp + hdrlen, caplen); 354 } 355 bp += BPF_WORDALIGN(caplen + hdrlen); 356 return(1); 357 } 358#undef bhp 359 360 return(0); 361} 362 363/* 364** BpfWrite -- Write packet to BPF device. 365** 366** Parameters: 367** rconn - packet to send. 368** 369** Returns: 370** True if write succeeded, False otherwise. 371** 372** Side Effects: 373** None. 374*/ 375int 376BpfWrite(rconn) 377 RMPCONN *rconn; 378{ 379 if (write(BpfFd, (char *)&rconn->rmp, rconn->rmplen) < 0) { 380 syslog(LOG_ERR, "write: %s: %m", EnetStr(rconn)); 381 return(0); 382 } 383 384 return(1); 385} 386 387/* 388** BpfClose -- Close a BPF device. 389** 390** Parameters: 391** None. 392** 393** Returns: 394** Nothing. 395** 396** Side Effects: 397** None. 398*/ 399void 400BpfClose() 401{ 402 struct ifreq ifr; 403 404 if (BpfPkt != NULL) { 405 free((char *)BpfPkt); 406 BpfPkt = NULL; 407 } 408 409 if (BpfFd == -1) 410 return; 411 412#ifdef MSG_EOR 413 ifr.ifr_addr.sa_len = RMP_ADDRLEN + 2; 414#endif 415 ifr.ifr_addr.sa_family = AF_UNSPEC; 416 memmove((char *)&ifr.ifr_addr.sa_data[0], &RmpMcastAddr[0], RMP_ADDRLEN); 417 if (ioctl(BpfFd, SIOCDELMULTI, (caddr_t)&ifr) < 0) 418 (void) ioctl(BpfFd, BIOCPROMISC, (caddr_t)0); 419 420 (void) close(BpfFd); 421 BpfFd = -1; 422} 423