1 /* 2 * Copyright (c) 1990, 1991, 1992, 1993, 1994, 1995, 1996 3 * The Regents of the University of California. All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that: (1) source code distributions 7 * retain the above copyright notice and this paragraph in its entirety, (2) 8 * distributions including binary code include the above copyright notice and 9 * this paragraph in its entirety in the documentation or other materials 10 * provided with the distribution, and (3) all advertising materials mentioning 11 * features or use of this software display the following acknowledgement: 12 * ``This product includes software developed by the University of California, 13 * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of 14 * the University nor the names of its contributors may be used to endorse 15 * or promote products derived from this software without specific prior 16 * written permission. 17 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED 18 * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF 19 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. 20 * 21 * packet filter subroutines for tcpdump 22 * Extraction/creation by Jeffrey Mogul, DECWRL 23 */ 24 25 #ifndef lint 26 static const char rcsid[] = 27 "@(#) $Header: /tcpdump/master/libpcap/pcap-pf.c,v 1.62 2000/10/28 00:01:30 guy Exp $ (LBL)"; 28 #endif 29 30 #ifdef HAVE_CONFIG_H 31 #include "config.h" 32 #endif 33 34 #include <sys/types.h> 35 #include <sys/time.h> 36 #include <sys/timeb.h> 37 #include <sys/socket.h> 38 #include <sys/file.h> 39 #include <sys/ioctl.h> 40 #include <net/pfilt.h> 41 42 struct mbuf; 43 struct rtentry; 44 #include <net/if.h> 45 46 #include <netinet/in.h> 47 #include <netinet/in_systm.h> 48 #include <netinet/ip.h> 49 #include <netinet/if_ether.h> 50 #include <netinet/ip_var.h> 51 #include <netinet/udp.h> 52 #include <netinet/udp_var.h> 53 #include <netinet/tcp.h> 54 #include <netinet/tcpip.h> 55 56 #include <ctype.h> 57 #include <errno.h> 58 #include <netdb.h> 59 #include <stdio.h> 60 #include <stdlib.h> 61 #include <string.h> 62 #include <unistd.h> 63 64 #include "pcap-int.h" 65 66 #ifdef HAVE_OS_PROTO_H 67 #include "os-proto.h" 68 #endif 69 70 /* 71 * BUFSPACE is the size in bytes of the packet read buffer. Most tcpdump 72 * applications aren't going to need more than 200 bytes of packet header 73 * and the read shouldn't return more packets than packetfilter's internal 74 * queue limit (bounded at 256). 75 */ 76 #define BUFSPACE (200 * 256) 77 78 int 79 pcap_read(pcap_t *pc, int cnt, pcap_handler callback, u_char *user) 80 { 81 register u_char *p, *bp; 82 struct bpf_insn *fcode; 83 register int cc, n, buflen, inc; 84 register struct enstamp *sp; 85 #ifdef LBL_ALIGN 86 struct enstamp stamp; 87 #endif 88 #ifdef PCAP_FDDIPAD 89 register int pad; 90 #endif 91 92 fcode = pc->md.use_bpf ? NULL : pc->fcode.bf_insns; 93 again: 94 cc = pc->cc; 95 if (cc == 0) { 96 cc = read(pc->fd, (char *)pc->buffer + pc->offset, pc->bufsize); 97 if (cc < 0) { 98 if (errno == EWOULDBLOCK) 99 return (0); 100 if (errno == EINVAL && 101 lseek(pc->fd, 0L, SEEK_CUR) + pc->bufsize < 0) { 102 /* 103 * Due to a kernel bug, after 2^31 bytes, 104 * the kernel file offset overflows and 105 * read fails with EINVAL. The lseek() 106 * to 0 will fix things. 107 */ 108 (void)lseek(pc->fd, 0L, SEEK_SET); 109 goto again; 110 } 111 snprintf(pc->errbuf, sizeof(pc->errbuf), "pf read: %s", 112 pcap_strerror(errno)); 113 return (-1); 114 } 115 bp = pc->buffer + pc->offset; 116 } else 117 bp = pc->bp; 118 /* 119 * Loop through each packet. 120 */ 121 n = 0; 122 #ifdef PCAP_FDDIPAD 123 if (pc->linktype == DLT_FDDI) 124 pad = pcap_fddipad; 125 else 126 pad = 0; 127 #endif 128 while (cc > 0) { 129 if (cc < sizeof(*sp)) { 130 snprintf(pc->errbuf, sizeof(pc->errbuf), 131 "pf short read (%d)", cc); 132 return (-1); 133 } 134 #ifdef LBL_ALIGN 135 if ((long)bp & 3) { 136 sp = &stamp; 137 memcpy((char *)sp, (char *)bp, sizeof(*sp)); 138 } else 139 #endif 140 sp = (struct enstamp *)bp; 141 if (sp->ens_stamplen != sizeof(*sp)) { 142 snprintf(pc->errbuf, sizeof(pc->errbuf), 143 "pf short stamplen (%d)", 144 sp->ens_stamplen); 145 return (-1); 146 } 147 148 p = bp + sp->ens_stamplen; 149 buflen = sp->ens_count; 150 if (buflen > pc->snapshot) 151 buflen = pc->snapshot; 152 153 /* Calculate inc before possible pad update */ 154 inc = ENALIGN(buflen + sp->ens_stamplen); 155 cc -= inc; 156 bp += inc; 157 #ifdef PCAP_FDDIPAD 158 p += pad; 159 buflen -= pad; 160 #endif 161 pc->md.TotPkts++; 162 pc->md.TotDrops += sp->ens_dropped; 163 pc->md.TotMissed = sp->ens_ifoverflows; 164 if (pc->md.OrigMissed < 0) 165 pc->md.OrigMissed = pc->md.TotMissed; 166 167 /* 168 * Short-circuit evaluation: if using BPF filter 169 * in kernel, no need to do it now. 170 */ 171 if (fcode == NULL || 172 bpf_filter(fcode, p, sp->ens_count, buflen)) { 173 struct pcap_pkthdr h; 174 pc->md.TotAccepted++; 175 h.ts = sp->ens_tstamp; 176 #ifdef PCAP_FDDIPAD 177 h.len = sp->ens_count - pad; 178 #else 179 h.len = sp->ens_count; 180 #endif 181 h.caplen = buflen; 182 (*callback)(user, &h, p); 183 if (++n >= cnt && cnt > 0) { 184 pc->cc = cc; 185 pc->bp = bp; 186 return (n); 187 } 188 } 189 } 190 pc->cc = 0; 191 return (n); 192 } 193 194 int 195 pcap_stats(pcap_t *p, struct pcap_stat *ps) 196 { 197 198 ps->ps_recv = p->md.TotAccepted; 199 ps->ps_drop = p->md.TotDrops; 200 ps->ps_ifdrop = p->md.TotMissed - p->md.OrigMissed; 201 return (0); 202 } 203 204 pcap_t * 205 pcap_open_live(char *device, int snaplen, int promisc, int to_ms, char *ebuf) 206 { 207 pcap_t *p; 208 short enmode; 209 int backlog = -1; /* request the most */ 210 struct enfilter Filter; 211 struct endevp devparams; 212 213 p = (pcap_t *)malloc(sizeof(*p)); 214 if (p == NULL) { 215 snprintf(ebuf, PCAP_ERRBUF_SIZE, 216 "pcap_open_live: %s", pcap_strerror(errno)); 217 return (0); 218 } 219 memset(p, 0, sizeof(*p)); 220 p->fd = pfopen(device, O_RDONLY); 221 if (p->fd < 0) { 222 snprintf(ebuf, PCAP_ERRBUF_SIZE, "pf open: %s: %s\n\ 223 your system may not be properly configured; see \"man packetfilter(4)\"\n", 224 device, pcap_strerror(errno)); 225 goto bad; 226 } 227 p->md.OrigMissed = -1; 228 enmode = ENTSTAMP|ENBATCH|ENNONEXCL; 229 if (promisc) 230 enmode |= ENPROMISC; 231 if (ioctl(p->fd, EIOCMBIS, (caddr_t)&enmode) < 0) { 232 snprintf(ebuf, PCAP_ERRBUF_SIZE, "EIOCMBIS: %s", 233 pcap_strerror(errno)); 234 goto bad; 235 } 236 #ifdef ENCOPYALL 237 /* Try to set COPYALL mode so that we see packets to ourself */ 238 enmode = ENCOPYALL; 239 (void)ioctl(p->fd, EIOCMBIS, (caddr_t)&enmode);/* OK if this fails */ 240 #endif 241 /* set the backlog */ 242 if (ioctl(p->fd, EIOCSETW, (caddr_t)&backlog) < 0) { 243 snprintf(ebuf, PCAP_ERRBUF_SIZE, "EIOCSETW: %s", 244 pcap_strerror(errno)); 245 goto bad; 246 } 247 /* discover interface type */ 248 if (ioctl(p->fd, EIOCDEVP, (caddr_t)&devparams) < 0) { 249 snprintf(ebuf, PCAP_ERRBUF_SIZE, "EIOCDEVP: %s", 250 pcap_strerror(errno)); 251 goto bad; 252 } 253 /* HACK: to compile prior to Ultrix 4.2 */ 254 #ifndef ENDT_FDDI 255 #define ENDT_FDDI 4 256 #endif 257 switch (devparams.end_dev_type) { 258 259 case ENDT_10MB: 260 p->linktype = DLT_EN10MB; 261 p->offset = 2; 262 break; 263 264 case ENDT_FDDI: 265 p->linktype = DLT_FDDI; 266 break; 267 268 default: 269 /* 270 * XXX 271 * Currently, the Ultrix packet filter supports only 272 * Ethernet and FDDI. Eventually, support for SLIP and PPP 273 * (and possibly others: T1?) should be added. 274 */ 275 #ifdef notdef 276 warning( 277 "Packet filter data-link type %d unknown, assuming Ethernet", 278 devparams.end_dev_type); 279 #endif 280 p->linktype = DLT_EN10MB; 281 p->offset = 2; 282 break; 283 } 284 /* set truncation */ 285 #ifdef PCAP_FDDIPAD 286 if (p->linktype == DLT_FDDI) 287 /* packetfilter includes the padding in the snapshot */ 288 snaplen += pcap_fddipad; 289 #endif 290 if (ioctl(p->fd, EIOCTRUNCATE, (caddr_t)&snaplen) < 0) { 291 snprintf(ebuf, PCAP_ERRBUF_SIZE, "EIOCTRUNCATE: %s", 292 pcap_strerror(errno)); 293 goto bad; 294 } 295 p->snapshot = snaplen; 296 /* accept all packets */ 297 memset(&Filter, 0, sizeof(Filter)); 298 Filter.enf_Priority = 37; /* anything > 2 */ 299 Filter.enf_FilterLen = 0; /* means "always true" */ 300 if (ioctl(p->fd, EIOCSETF, (caddr_t)&Filter) < 0) { 301 snprintf(ebuf, PCAP_ERRBUF_SIZE, "EIOCSETF: %s", 302 pcap_strerror(errno)); 303 goto bad; 304 } 305 306 if (to_ms != 0) { 307 struct timeval timeout; 308 timeout.tv_sec = to_ms / 1000; 309 timeout.tv_usec = (to_ms * 1000) % 1000000; 310 if (ioctl(p->fd, EIOCSRTIMEOUT, (caddr_t)&timeout) < 0) { 311 snprintf(ebuf, PCAP_ERRBUF_SIZE, "EIOCSRTIMEOUT: %s", 312 pcap_strerror(errno)); 313 goto bad; 314 } 315 } 316 p->bufsize = BUFSPACE; 317 p->buffer = (u_char*)malloc(p->bufsize + p->offset); 318 319 return (p); 320 bad: 321 free(p); 322 return (NULL); 323 } 324 325 int 326 pcap_setfilter(pcap_t *p, struct bpf_program *fp) 327 { 328 /* 329 * See if BIOCSETF works. If it does, the kernel supports 330 * BPF-style filters, and we do not need to do post-filtering. 331 */ 332 p->md.use_bpf = (ioctl(p->fd, BIOCSETF, (caddr_t)fp) >= 0); 333 if (p->md.use_bpf) { 334 struct bpf_version bv; 335 336 if (ioctl(p->fd, BIOCVERSION, (caddr_t)&bv) < 0) { 337 snprintf(p->errbuf, sizeof(p->errbuf), 338 "BIOCVERSION: %s", pcap_strerror(errno)); 339 return (-1); 340 } 341 else if (bv.bv_major != BPF_MAJOR_VERSION || 342 bv.bv_minor < BPF_MINOR_VERSION) { 343 fprintf(stderr, 344 "requires bpf language %d.%d or higher; kernel is %d.%d", 345 BPF_MAJOR_VERSION, BPF_MINOR_VERSION, 346 bv.bv_major, bv.bv_minor); 347 /* don't give up, just be inefficient */ 348 p->md.use_bpf = 0; 349 } 350 } else { 351 if (install_bpf_program(p, fp) < 0) 352 return (-1); 353 } 354 355 /*XXX this goes in tcpdump*/ 356 if (p->md.use_bpf) 357 fprintf(stderr, "tcpdump: Using kernel BPF filter\n"); 358 else 359 fprintf(stderr, "tcpdump: Filtering in user process\n"); 360 return (0); 361 } 362