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1 /*
2  * Copyright (c) 1993, 1994, 1995, 1996, 1997
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 #ifndef lint
22 static const char rcsid[] _U_ =
23     "@(#) $Header: /tcpdump/master/libpcap/pcap-snoop.c,v 1.54.2.1 2005/05/03 18:54:38 guy Exp $ (LBL)";
24 #endif
25 
26 #ifdef HAVE_CONFIG_H
27 #include "config.h"
28 #endif
29 
30 #include <sys/param.h>
31 #include <sys/file.h>
32 #include <sys/ioctl.h>
33 #include <sys/socket.h>
34 #include <sys/time.h>
35 
36 #include <net/raw.h>
37 #include <net/if.h>
38 
39 #include <netinet/in.h>
40 #include <netinet/in_systm.h>
41 #include <netinet/ip.h>
42 #include <netinet/if_ether.h>
43 #include <netinet/ip_var.h>
44 #include <netinet/udp.h>
45 #include <netinet/udp_var.h>
46 #include <netinet/tcp.h>
47 #include <netinet/tcpip.h>
48 
49 #include <errno.h>
50 #include <stdio.h>
51 #include <stdlib.h>
52 #include <string.h>
53 #include <unistd.h>
54 
55 #include "pcap-int.h"
56 
57 #ifdef HAVE_OS_PROTO_H
58 #include "os-proto.h"
59 #endif
60 
61 static int
pcap_read_snoop(pcap_t * p,int cnt,pcap_handler callback,u_char * user)62 pcap_read_snoop(pcap_t *p, int cnt, pcap_handler callback, u_char *user)
63 {
64 	int cc;
65 	register struct snoopheader *sh;
66 	register u_int datalen;
67 	register u_int caplen;
68 	register u_char *cp;
69 
70 again:
71 	/*
72 	 * Has "pcap_breakloop()" been called?
73 	 */
74 	if (p->break_loop) {
75 		/*
76 		 * Yes - clear the flag that indicates that it
77 		 * has, and return -2 to indicate that we were
78 		 * told to break out of the loop.
79 		 */
80 		p->break_loop = 0;
81 		return (-2);
82 	}
83 	cc = read(p->fd, (char *)p->buffer, p->bufsize);
84 	if (cc < 0) {
85 		/* Don't choke when we get ptraced */
86 		switch (errno) {
87 
88 		case EINTR:
89 			goto again;
90 
91 		case EWOULDBLOCK:
92 			return (0);			/* XXX */
93 		}
94 		snprintf(p->errbuf, sizeof(p->errbuf),
95 		    "read: %s", pcap_strerror(errno));
96 		return (-1);
97 	}
98 	sh = (struct snoopheader *)p->buffer;
99 	datalen = sh->snoop_packetlen;
100 
101 	/*
102 	 * XXX - Sigh, snoop_packetlen is a 16 bit quantity.  If we
103 	 * got a short length, but read a full sized snoop pakcet,
104 	 * assume we overflowed and add back the 64K...
105 	 */
106 	if (cc == (p->snapshot + sizeof(struct snoopheader)) &&
107 	    (datalen < p->snapshot))
108 		datalen += (64 * 1024);
109 
110 	caplen = (datalen < p->snapshot) ? datalen : p->snapshot;
111 	cp = (u_char *)(sh + 1) + p->offset;		/* XXX */
112 
113 	/*
114 	 * XXX unfortunately snoop loopback isn't exactly like
115 	 * BSD's.  The address family is encoded in the first 2
116 	 * bytes rather than the first 4 bytes!  Luckily the last
117 	 * two snoop loopback bytes are zeroed.
118 	 */
119 	if (p->linktype == DLT_NULL && *((short *)(cp + 2)) == 0) {
120 		u_int *uip = (u_int *)cp;
121 		*uip >>= 16;
122 	}
123 
124 	if (p->fcode.bf_insns == NULL ||
125 	    bpf_filter(p->fcode.bf_insns, cp, datalen, caplen)) {
126 		struct pcap_pkthdr h;
127 		++p->md.stat.ps_recv;
128 		h.ts.tv_sec = sh->snoop_timestamp.tv_sec;
129 		h.ts.tv_usec = sh->snoop_timestamp.tv_usec;
130 		h.len = datalen;
131 		h.caplen = caplen;
132 		(*callback)(user, &h, cp);
133 		return (1);
134 	}
135 	return (0);
136 }
137 
138 static int
pcap_inject_snoop(pcap_t * p,const void * buf,size_t size)139 pcap_inject_snoop(pcap_t *p, const void *buf, size_t size)
140 {
141 	int ret;
142 
143 	/*
144 	 * XXX - libnet overwrites the source address with what I
145 	 * presume is the interface's address; is that required?
146 	 */
147 	ret = write(p->fd, buf, size);
148 	if (ret == -1) {
149 		snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "send: %s",
150 		    pcap_strerror(errno));
151 		return (-1);
152 	}
153 	return (ret);
154 }
155 
156 static int
pcap_stats_snoop(pcap_t * p,struct pcap_stat * ps)157 pcap_stats_snoop(pcap_t *p, struct pcap_stat *ps)
158 {
159 	register struct rawstats *rs;
160 	struct rawstats rawstats;
161 
162 	rs = &rawstats;
163 	memset(rs, 0, sizeof(*rs));
164 	if (ioctl(p->fd, SIOCRAWSTATS, (char *)rs) < 0) {
165 		snprintf(p->errbuf, sizeof(p->errbuf),
166 		    "SIOCRAWSTATS: %s", pcap_strerror(errno));
167 		return (-1);
168 	}
169 
170 	/*
171 	 * "ifdrops" are those dropped by the network interface
172 	 * due to resource shortages or hardware errors.
173 	 *
174 	 * "sbdrops" are those dropped due to socket buffer limits.
175 	 *
176 	 * As filter is done in userland, "sbdrops" counts packets
177 	 * regardless of whether they would've passed the filter.
178 	 *
179 	 * XXX - does this count *all* Snoop or Drain sockets,
180 	 * rather than just this socket?  If not, why does it have
181 	 * both Snoop and Drain statistics?
182 	 */
183 	p->md.stat.ps_drop =
184 	    rs->rs_snoop.ss_ifdrops + rs->rs_snoop.ss_sbdrops +
185 	    rs->rs_drain.ds_ifdrops + rs->rs_drain.ds_sbdrops;
186 
187 	/*
188 	 * "ps_recv" counts only packets that passed the filter.
189 	 * As filtering is done in userland, this does not include
190 	 * packets dropped because we ran out of buffer space.
191 	 */
192 	*ps = p->md.stat;
193 	return (0);
194 }
195 
196 /* XXX can't disable promiscuous */
197 pcap_t *
pcap_open_live(const char * device,int snaplen,int promisc,int to_ms,char * ebuf)198 pcap_open_live(const char *device, int snaplen, int promisc, int to_ms,
199     char *ebuf)
200 {
201 	int fd;
202 	struct sockaddr_raw sr;
203 	struct snoopfilter sf;
204 	u_int v;
205 	int ll_hdrlen;
206 	int snooplen;
207 	pcap_t *p;
208 	struct ifreq ifr;
209 
210 	p = (pcap_t *)malloc(sizeof(*p));
211 	if (p == NULL) {
212 		snprintf(ebuf, PCAP_ERRBUF_SIZE, "malloc: %s",
213 		    pcap_strerror(errno));
214 		return (NULL);
215 	}
216 	memset(p, 0, sizeof(*p));
217 	fd = socket(PF_RAW, SOCK_RAW, RAWPROTO_SNOOP);
218 	if (fd < 0) {
219 		snprintf(ebuf, PCAP_ERRBUF_SIZE, "snoop socket: %s",
220 		    pcap_strerror(errno));
221 		goto bad;
222 	}
223 	p->fd = fd;
224 	memset(&sr, 0, sizeof(sr));
225 	sr.sr_family = AF_RAW;
226 	(void)strncpy(sr.sr_ifname, device, sizeof(sr.sr_ifname));
227 	if (bind(fd, (struct sockaddr *)&sr, sizeof(sr))) {
228 		snprintf(ebuf, PCAP_ERRBUF_SIZE, "snoop bind: %s",
229 		    pcap_strerror(errno));
230 		goto bad;
231 	}
232 	memset(&sf, 0, sizeof(sf));
233 	if (ioctl(fd, SIOCADDSNOOP, &sf) < 0) {
234 		snprintf(ebuf, PCAP_ERRBUF_SIZE, "SIOCADDSNOOP: %s",
235 		    pcap_strerror(errno));
236 		goto bad;
237 	}
238 	v = 64 * 1024;
239 	(void)setsockopt(fd, SOL_SOCKET, SO_RCVBUF, (char *)&v, sizeof(v));
240 	/*
241 	 * XXX hack - map device name to link layer type
242 	 */
243 	if (strncmp("et", device, 2) == 0 ||	/* Challenge 10 Mbit */
244 	    strncmp("ec", device, 2) == 0 ||	/* Indigo/Indy 10 Mbit,
245 						   O2 10/100 */
246 	    strncmp("ef", device, 2) == 0 ||	/* O200/2000 10/100 Mbit */
247 	    strncmp("eg", device, 2) == 0 ||	/* Octane/O2xxx/O3xxx Gigabit */
248 	    strncmp("gfe", device, 3) == 0 ||	/* GIO 100 Mbit */
249 	    strncmp("fxp", device, 3) == 0 ||	/* Challenge VME Enet */
250 	    strncmp("ep", device, 2) == 0 ||	/* Challenge 8x10 Mbit EPLEX */
251 	    strncmp("vfe", device, 3) == 0 ||	/* Challenge VME 100Mbit */
252 	    strncmp("fa", device, 2) == 0 ||
253 	    strncmp("qaa", device, 3) == 0 ||
254 	    strncmp("cip", device, 3) == 0 ||
255 	    strncmp("el", device, 2) == 0) {
256 		p->linktype = DLT_EN10MB;
257 		p->offset = RAW_HDRPAD(sizeof(struct ether_header));
258 		ll_hdrlen = sizeof(struct ether_header);
259 		/*
260 		 * This is (presumably) a real Ethernet capture; give it a
261 		 * link-layer-type list with DLT_EN10MB and DLT_DOCSIS, so
262 		 * that an application can let you choose it, in case you're
263 		 * capturing DOCSIS traffic that a Cisco Cable Modem
264 		 * Termination System is putting out onto an Ethernet (it
265 		 * doesn't put an Ethernet header onto the wire, it puts raw
266 		 * DOCSIS frames out on the wire inside the low-level
267 		 * Ethernet framing).
268 		 *
269 		 * XXX - are there any sorts of "fake Ethernet" that have
270 		 * Ethernet link-layer headers but that *shouldn't offer
271 		 * DLT_DOCSIS as a Cisco CMTS won't put traffic onto it
272 		 * or get traffic bridged onto it?  "el" is for ATM LANE
273 		 * Ethernet devices, so that might be the case for them;
274 		 * the same applies for "qaa" classical IP devices.  If
275 		 * "fa" devices are for FORE SPANS, that'd apply to them
276 		 * as well; what are "cip" devices - some other ATM
277 		 * Classical IP devices?
278 		 */
279 		p->dlt_list = (u_int *) malloc(sizeof(u_int) * 2);
280 		/*
281 		 * If that fails, just leave the list empty.
282 		 */
283 		if (p->dlt_list != NULL) {
284 			p->dlt_list[0] = DLT_EN10MB;
285 			p->dlt_list[1] = DLT_DOCSIS;
286 			p->dlt_count = 2;
287 		}
288 	} else if (strncmp("ipg", device, 3) == 0 ||
289 		   strncmp("rns", device, 3) == 0 ||	/* O2/200/2000 FDDI */
290 		   strncmp("xpi", device, 3) == 0) {
291 		p->linktype = DLT_FDDI;
292 		p->offset = 3;				/* XXX yeah? */
293 		ll_hdrlen = 13;
294 	} else if (strncmp("ppp", device, 3) == 0) {
295 		p->linktype = DLT_RAW;
296 		ll_hdrlen = 0;	/* DLT_RAW meaning "no PPP header, just the IP packet"? */
297 	} else if (strncmp("qfa", device, 3) == 0) {
298 		p->linktype = DLT_IP_OVER_FC;
299 		ll_hdrlen = 24;
300 	} else if (strncmp("pl", device, 2) == 0) {
301 		p->linktype = DLT_RAW;
302 		ll_hdrlen = 0;	/* Cray UNICOS/mp pseudo link */
303 	} else if (strncmp("lo", device, 2) == 0) {
304 		p->linktype = DLT_NULL;
305 		ll_hdrlen = 4;
306 	} else {
307 		snprintf(ebuf, PCAP_ERRBUF_SIZE,
308 		    "snoop: unknown physical layer type");
309 		goto bad;
310 	}
311 #ifdef SIOCGIFMTU
312 	/*
313 	 * XXX - IRIX appears to give you an error if you try to set the
314 	 * capture length to be greater than the MTU, so let's try to get
315 	 * the MTU first and, if that succeeds, trim the snap length
316 	 * to be no greater than the MTU.
317 	 */
318 	(void)strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name));
319 	if (ioctl(fd, SIOCGIFMTU, (char *)&ifr) < 0) {
320 		snprintf(ebuf, PCAP_ERRBUF_SIZE, "SIOCGIFMTU: %s",
321 		    pcap_strerror(errno));
322 		goto bad;
323 	}
324 	/*
325 	 * OK, we got it.
326 	 *
327 	 * XXX - some versions of IRIX 6.5 define "ifr_mtu" and have an
328 	 * "ifru_metric" member of the "ifr_ifru" union in an "ifreq"
329 	 * structure, others don't.
330 	 *
331 	 * I've no idea what's going on, so, if "ifr_mtu" isn't defined,
332 	 * we define it as "ifr_metric", as using that field appears to
333 	 * work on the versions that lack "ifr_mtu" (and, on those that
334 	 * don't lack it, "ifru_metric" and "ifru_mtu" are both "int"
335 	 * members of the "ifr_ifru" union, which suggests that they
336 	 * may be interchangeable in this case).
337 	 */
338 #ifndef ifr_mtu
339 #define ifr_mtu	ifr_metric
340 #endif
341 	if (snaplen > ifr.ifr_mtu + ll_hdrlen)
342 		snaplen = ifr.ifr_mtu + ll_hdrlen;
343 #endif
344 
345 	/*
346 	 * The argument to SIOCSNOOPLEN is the number of link-layer
347 	 * payload bytes to capture - it doesn't count link-layer
348 	 * header bytes.
349 	 */
350 	snooplen = snaplen - ll_hdrlen;
351 	if (snooplen < 0)
352 		snooplen = 0;
353 	if (ioctl(fd, SIOCSNOOPLEN, &snooplen) < 0) {
354 		snprintf(ebuf, PCAP_ERRBUF_SIZE, "SIOCSNOOPLEN: %s",
355 		    pcap_strerror(errno));
356 		goto bad;
357 	}
358 	p->snapshot = snaplen;
359 	v = 1;
360 	if (ioctl(fd, SIOCSNOOPING, &v) < 0) {
361 		snprintf(ebuf, PCAP_ERRBUF_SIZE, "SIOCSNOOPING: %s",
362 		    pcap_strerror(errno));
363 		goto bad;
364 	}
365 
366 	p->bufsize = 4096;				/* XXX */
367 	p->buffer = (u_char *)malloc(p->bufsize);
368 	if (p->buffer == NULL) {
369 		snprintf(ebuf, PCAP_ERRBUF_SIZE, "malloc: %s",
370 		    pcap_strerror(errno));
371 		goto bad;
372 	}
373 
374 	/*
375 	 * "p->fd" is a socket, so "select()" should work on it.
376 	 */
377 	p->selectable_fd = p->fd;
378 
379 	p->read_op = pcap_read_snoop;
380 	p->inject_op = pcap_inject_snoop;
381 	p->setfilter_op = install_bpf_program;	/* no kernel filtering */
382 	p->setdirection_op = NULL;	/* Not implemented. */
383 	p->set_datalink_op = NULL;	/* can't change data link type */
384 	p->getnonblock_op = pcap_getnonblock_fd;
385 	p->setnonblock_op = pcap_setnonblock_fd;
386 	p->stats_op = pcap_stats_snoop;
387 	p->close_op = pcap_close_common;
388 
389 	return (p);
390  bad:
391 	(void)close(fd);
392 	/*
393 	 * Get rid of any link-layer type list we allocated.
394 	 */
395 	if (p->dlt_list != NULL)
396 		free(p->dlt_list);
397 	free(p);
398 	return (NULL);
399 }
400 
401 int
pcap_platform_finddevs(pcap_if_t ** alldevsp,char * errbuf)402 pcap_platform_finddevs(pcap_if_t **alldevsp, char *errbuf)
403 {
404 	return (0);
405 }
406