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21 * packet filter subroutines for tcpdump
22 * Extraction/creation by Jeffrey Mogul, DECWRL
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)";
34 #include <sys/types.h>
36 #include <sys/timeb.h>
37 #include <sys/socket.h>
39 #include <sys/ioctl.h>
40 #include <net/pfilt.h>
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>
66 #ifdef HAVE_OS_PROTO_H
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).
76 #define BUFSPACE (200 * 256)
79 pcap_read(pcap_t *pc, int cnt, pcap_handler callback, u_char *user)
81 register u_char *p, *bp;
82 struct bpf_insn *fcode;
83 register int cc, n, buflen, inc;
84 register struct enstamp *sp;
92 fcode = pc->md.use_bpf ? NULL : pc->fcode.bf_insns;
96 cc = read(pc->fd, (char *)pc->buffer + pc->offset, pc->bufsize);
98 if (errno == EWOULDBLOCK)
100 if (errno == EINVAL &&
101 lseek(pc->fd, 0L, SEEK_CUR) + pc->bufsize < 0) {
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.
108 (void)lseek(pc->fd, 0L, SEEK_SET);
111 snprintf(pc->errbuf, sizeof(pc->errbuf), "pf read: %s",
112 pcap_strerror(errno));
115 bp = pc->buffer + pc->offset;
119 * Loop through each packet.
123 if (pc->linktype == DLT_FDDI)
129 if (cc < sizeof(*sp)) {
130 snprintf(pc->errbuf, sizeof(pc->errbuf),
131 "pf short read (%d)", cc);
137 memcpy((char *)sp, (char *)bp, sizeof(*sp));
140 sp = (struct enstamp *)bp;
141 if (sp->ens_stamplen != sizeof(*sp)) {
142 snprintf(pc->errbuf, sizeof(pc->errbuf),
143 "pf short stamplen (%d)",
148 p = bp + sp->ens_stamplen;
149 buflen = sp->ens_count;
150 if (buflen > pc->snapshot)
151 buflen = pc->snapshot;
153 /* Calculate inc before possible pad update */
154 inc = ENALIGN(buflen + sp->ens_stamplen);
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;
168 * Short-circuit evaluation: if using BPF filter
169 * in kernel, no need to do it now.
172 bpf_filter(fcode, p, sp->ens_count, buflen)) {
173 struct pcap_pkthdr h;
174 pc->md.TotAccepted++;
175 h.ts = sp->ens_tstamp;
177 h.len = sp->ens_count - pad;
179 h.len = sp->ens_count;
182 (*callback)(user, &h, p);
183 if (++n >= cnt && cnt > 0) {
195 pcap_stats(pcap_t *p, struct pcap_stat *ps)
198 ps->ps_recv = p->md.TotAccepted;
199 ps->ps_drop = p->md.TotDrops;
200 ps->ps_ifdrop = p->md.TotMissed - p->md.OrigMissed;
205 pcap_open_live(char *device, int snaplen, int promisc, int to_ms, char *ebuf)
209 int backlog = -1; /* request the most */
210 struct enfilter Filter;
211 struct endevp devparams;
213 p = (pcap_t *)malloc(sizeof(*p));
215 snprintf(ebuf, PCAP_ERRBUF_SIZE,
216 "pcap_open_live: %s", pcap_strerror(errno));
219 memset(p, 0, sizeof(*p));
220 p->fd = pfopen(device, O_RDONLY);
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));
227 p->md.OrigMissed = -1;
228 enmode = ENTSTAMP|ENBATCH|ENNONEXCL;
231 if (ioctl(p->fd, EIOCMBIS, (caddr_t)&enmode) < 0) {
232 snprintf(ebuf, PCAP_ERRBUF_SIZE, "EIOCMBIS: %s",
233 pcap_strerror(errno));
237 /* Try to set COPYALL mode so that we see packets to ourself */
239 (void)ioctl(p->fd, EIOCMBIS, (caddr_t)&enmode);/* OK if this fails */
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));
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));
253 /* HACK: to compile prior to Ultrix 4.2 */
257 switch (devparams.end_dev_type) {
260 p->linktype = DLT_EN10MB;
265 p->linktype = DLT_FDDI;
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.
277 "Packet filter data-link type %d unknown, assuming Ethernet",
278 devparams.end_dev_type);
280 p->linktype = DLT_EN10MB;
286 if (p->linktype == DLT_FDDI)
287 /* packetfilter includes the padding in the snapshot */
288 snaplen += pcap_fddipad;
290 if (ioctl(p->fd, EIOCTRUNCATE, (caddr_t)&snaplen) < 0) {
291 snprintf(ebuf, PCAP_ERRBUF_SIZE, "EIOCTRUNCATE: %s",
292 pcap_strerror(errno));
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));
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));
316 p->bufsize = BUFSPACE;
317 p->buffer = (u_char*)malloc(p->bufsize + p->offset);
326 pcap_setfilter(pcap_t *p, struct bpf_program *fp)
329 * See if BIOCSETF works. If it does, the kernel supports
330 * BPF-style filters, and we do not need to do post-filtering.
332 p->md.use_bpf = (ioctl(p->fd, BIOCSETF, (caddr_t)fp) >= 0);
334 struct bpf_version bv;
336 if (ioctl(p->fd, BIOCVERSION, (caddr_t)&bv) < 0) {
337 snprintf(p->errbuf, sizeof(p->errbuf),
338 "BIOCVERSION: %s", pcap_strerror(errno));
341 else if (bv.bv_major != BPF_MAJOR_VERSION ||
342 bv.bv_minor < BPF_MINOR_VERSION) {
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 */
351 if (install_bpf_program(p, fp) < 0)
355 /*XXX this goes in tcpdump*/
357 fprintf(stderr, "tcpdump: Using kernel BPF filter\n");
359 fprintf(stderr, "tcpdump: Filtering in user process\n");