1/*
2 * pcap-linux.c: Packet capture interface to the Linux kernel
3 *
4 * Copyright (c) 2000 Torsten Landschoff <torsten@debian.org>
5 * Sebastian Krahmer <krahmer@cs.uni-potsdam.de>
6 *
7 * License: BSD
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 *
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in
17 * the documentation and/or other materials provided with the
18 * distribution.
19 * 3. The names of the authors may not be used to endorse or promote
20 * products derived from this software without specific prior
21 * written permission.
22 *
23 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
24 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
25 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
26 */
27
28#ifndef lint
29static const char rcsid[] _U_ =
| 1/*
2 * pcap-linux.c: Packet capture interface to the Linux kernel
3 *
4 * Copyright (c) 2000 Torsten Landschoff <torsten@debian.org>
5 * Sebastian Krahmer <krahmer@cs.uni-potsdam.de>
6 *
7 * License: BSD
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 *
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in
17 * the documentation and/or other materials provided with the
18 * distribution.
19 * 3. The names of the authors may not be used to endorse or promote
20 * products derived from this software without specific prior
21 * written permission.
22 *
23 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
24 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
25 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
26 */
27
28#ifndef lint
29static const char rcsid[] _U_ =
|
30 "@(#) $Header: /tcpdump/master/libpcap/pcap-linux.c,v 1.110.2.6 2005/08/16 04:25:26 guy Exp $ (LBL)";
| 30 "@(#) $Header: /tcpdump/master/libpcap/pcap-linux.c,v 1.110.2.14 2006/10/12 17:26:58 guy Exp $ (LBL)";
|
31#endif
32
33/*
34 * Known problems with 2.0[.x] kernels:
35 *
36 * - The loopback device gives every packet twice; on 2.2[.x] kernels,
37 * if we use PF_PACKET, we can filter out the transmitted version
38 * of the packet by using data in the "sockaddr_ll" returned by
39 * "recvfrom()", but, on 2.0[.x] kernels, we have to use
40 * PF_INET/SOCK_PACKET, which means "recvfrom()" supplies a
41 * "sockaddr_pkt" which doesn't give us enough information to let
42 * us do that.
43 *
44 * - We have to set the interface's IFF_PROMISC flag ourselves, if
45 * we're to run in promiscuous mode, which means we have to turn
46 * it off ourselves when we're done; the kernel doesn't keep track
47 * of how many sockets are listening promiscuously, which means
48 * it won't get turned off automatically when no sockets are
49 * listening promiscuously. We catch "pcap_close()" and, for
50 * interfaces we put into promiscuous mode, take them out of
51 * promiscuous mode - which isn't necessarily the right thing to
52 * do, if another socket also requested promiscuous mode between
53 * the time when we opened the socket and the time when we close
54 * the socket.
55 *
56 * - MSG_TRUNC isn't supported, so you can't specify that "recvfrom()"
57 * return the amount of data that you could have read, rather than
58 * the amount that was returned, so we can't just allocate a buffer
59 * whose size is the snapshot length and pass the snapshot length
60 * as the byte count, and also pass MSG_TRUNC, so that the return
61 * value tells us how long the packet was on the wire.
62 *
63 * This means that, if we want to get the actual size of the packet,
64 * so we can return it in the "len" field of the packet header,
65 * we have to read the entire packet, not just the part that fits
66 * within the snapshot length, and thus waste CPU time copying data
67 * from the kernel that our caller won't see.
68 *
69 * We have to get the actual size, and supply it in "len", because
70 * otherwise, the IP dissector in tcpdump, for example, will complain
71 * about "truncated-ip", as the packet will appear to have been
72 * shorter, on the wire, than the IP header said it should have been.
73 */
74
75
76#ifdef HAVE_CONFIG_H
77#include "config.h"
78#endif
79
80#include "pcap-int.h"
81#include "sll.h"
82
83#ifdef HAVE_DAG_API
84#include "pcap-dag.h"
85#endif /* HAVE_DAG_API */
86
87#ifdef HAVE_SEPTEL_API
88#include "pcap-septel.h"
89#endif /* HAVE_SEPTEL_API */
90
91#include <errno.h>
92#include <stdlib.h>
93#include <unistd.h>
94#include <fcntl.h>
95#include <string.h>
96#include <sys/socket.h>
97#include <sys/ioctl.h>
98#include <sys/utsname.h>
99#include <net/if.h>
100#include <netinet/in.h>
101#include <linux/if_ether.h>
102#include <net/if_arp.h>
103
104/*
105 * If PF_PACKET is defined, we can use {SOCK_RAW,SOCK_DGRAM}/PF_PACKET
106 * sockets rather than SOCK_PACKET sockets.
107 *
108 * To use them, we include <linux/if_packet.h> rather than
109 * <netpacket/packet.h>; we do so because
110 *
111 * some Linux distributions (e.g., Slackware 4.0) have 2.2 or
112 * later kernels and libc5, and don't provide a <netpacket/packet.h>
113 * file;
114 *
115 * not all versions of glibc2 have a <netpacket/packet.h> file
116 * that defines stuff needed for some of the 2.4-or-later-kernel
117 * features, so if the system has a 2.4 or later kernel, we
118 * still can't use those features.
119 *
120 * We're already including a number of other <linux/XXX.h> headers, and
121 * this code is Linux-specific (no other OS has PF_PACKET sockets as
122 * a raw packet capture mechanism), so it's not as if you gain any
123 * useful portability by using <netpacket/packet.h>
124 *
125 * XXX - should we just include <linux/if_packet.h> even if PF_PACKET
126 * isn't defined? It only defines one data structure in 2.0.x, so
127 * it shouldn't cause any problems.
128 */
129#ifdef PF_PACKET
130# include <linux/if_packet.h>
131
132 /*
133 * On at least some Linux distributions (for example, Red Hat 5.2),
134 * there's no <netpacket/packet.h> file, but PF_PACKET is defined if
135 * you include <sys/socket.h>, but <linux/if_packet.h> doesn't define
136 * any of the PF_PACKET stuff such as "struct sockaddr_ll" or any of
137 * the PACKET_xxx stuff.
138 *
139 * So we check whether PACKET_HOST is defined, and assume that we have
140 * PF_PACKET sockets only if it is defined.
141 */
142# ifdef PACKET_HOST
143# define HAVE_PF_PACKET_SOCKETS
144# endif /* PACKET_HOST */
145#endif /* PF_PACKET */
146
147#ifdef SO_ATTACH_FILTER
148#include <linux/types.h>
149#include <linux/filter.h>
150#endif
151
152#ifndef __GLIBC__
153typedef int socklen_t;
154#endif
155
156#ifndef MSG_TRUNC
157/*
158 * This is being compiled on a system that lacks MSG_TRUNC; define it
159 * with the value it has in the 2.2 and later kernels, so that, on
160 * those kernels, when we pass it in the flags argument to "recvfrom()"
161 * we're passing the right value and thus get the MSG_TRUNC behavior
162 * we want. (We don't get that behavior on 2.0[.x] kernels, because
163 * they didn't support MSG_TRUNC.)
164 */
165#define MSG_TRUNC 0x20
166#endif
167
168#ifndef SOL_PACKET
169/*
170 * This is being compiled on a system that lacks SOL_PACKET; define it
171 * with the value it has in the 2.2 and later kernels, so that we can
172 * set promiscuous mode in the good modern way rather than the old
173 * 2.0-kernel crappy way.
174 */
175#define SOL_PACKET 263
176#endif
177
178#define MAX_LINKHEADER_SIZE 256
179
180/*
181 * When capturing on all interfaces we use this as the buffer size.
182 * Should be bigger then all MTUs that occur in real life.
183 * 64kB should be enough for now.
184 */
185#define BIGGER_THAN_ALL_MTUS (64*1024)
186
187/*
188 * Prototypes for internal functions
189 */
190static void map_arphrd_to_dlt(pcap_t *, int, int);
191static int live_open_old(pcap_t *, const char *, int, int, char *);
192static int live_open_new(pcap_t *, const char *, int, int, char *);
193static int pcap_read_linux(pcap_t *, int, pcap_handler, u_char *);
194static int pcap_read_packet(pcap_t *, pcap_handler, u_char *);
195static int pcap_inject_linux(pcap_t *, const void *, size_t);
196static int pcap_stats_linux(pcap_t *, struct pcap_stat *);
197static int pcap_setfilter_linux(pcap_t *, struct bpf_program *);
198static int pcap_setdirection_linux(pcap_t *, pcap_direction_t);
199static void pcap_close_linux(pcap_t *);
200
201/*
202 * Wrap some ioctl calls
203 */
204#ifdef HAVE_PF_PACKET_SOCKETS
205static int iface_get_id(int fd, const char *device, char *ebuf);
206#endif
207static int iface_get_mtu(int fd, const char *device, char *ebuf);
208static int iface_get_arptype(int fd, const char *device, char *ebuf);
209#ifdef HAVE_PF_PACKET_SOCKETS
210static int iface_bind(int fd, int ifindex, char *ebuf);
211#endif
212static int iface_bind_old(int fd, const char *device, char *ebuf);
213
214#ifdef SO_ATTACH_FILTER
215static int fix_program(pcap_t *handle, struct sock_fprog *fcode);
216static int fix_offset(struct bpf_insn *p);
217static int set_kernel_filter(pcap_t *handle, struct sock_fprog *fcode);
218static int reset_kernel_filter(pcap_t *handle);
219
220static struct sock_filter total_insn
221 = BPF_STMT(BPF_RET | BPF_K, 0);
222static struct sock_fprog total_fcode
223 = { 1, &total_insn };
224#endif
225
226/*
227 * Get a handle for a live capture from the given device. You can
228 * pass NULL as device to get all packages (without link level
229 * information of course). If you pass 1 as promisc the interface
230 * will be set to promiscous mode (XXX: I think this usage should
231 * be deprecated and functions be added to select that later allow
232 * modification of that values -- Torsten).
233 *
234 * See also pcap(3).
235 */
236pcap_t *
237pcap_open_live(const char *device, int snaplen, int promisc, int to_ms,
238 char *ebuf)
239{
240 pcap_t *handle;
241 int mtu;
242 int err;
243 int live_open_ok = 0;
244 struct utsname utsname;
245
246#ifdef HAVE_DAG_API
247 if (strstr(device, "dag")) {
248 return dag_open_live(device, snaplen, promisc, to_ms, ebuf);
249 }
250#endif /* HAVE_DAG_API */
251
252#ifdef HAVE_SEPTEL_API
253 if (strstr(device, "septel")) {
254 return septel_open_live(device, snaplen, promisc, to_ms, ebuf);
255 }
256#endif /* HAVE_SEPTEL_API */
257
258 /* Allocate a handle for this session. */
259
260 handle = malloc(sizeof(*handle));
261 if (handle == NULL) {
262 snprintf(ebuf, PCAP_ERRBUF_SIZE, "malloc: %s",
263 pcap_strerror(errno));
264 return NULL;
265 }
266
267 /* Initialize some components of the pcap structure. */
268
269 memset(handle, 0, sizeof(*handle));
270 handle->snapshot = snaplen;
271 handle->md.timeout = to_ms;
272
273 /*
274 * NULL and "any" are special devices which give us the hint to
275 * monitor all devices.
276 */
277 if (!device || strcmp(device, "any") == 0) {
278 device = NULL;
279 handle->md.device = strdup("any");
280 if (promisc) {
281 promisc = 0;
282 /* Just a warning. */
283 snprintf(ebuf, PCAP_ERRBUF_SIZE,
284 "Promiscuous mode not supported on the \"any\" device");
285 }
286
287 } else
288 handle->md.device = strdup(device);
289
290 if (handle->md.device == NULL) {
291 snprintf(ebuf, PCAP_ERRBUF_SIZE, "strdup: %s",
292 pcap_strerror(errno) );
293 free(handle);
294 return NULL;
295 }
296
297 /*
298 * Current Linux kernels use the protocol family PF_PACKET to
299 * allow direct access to all packets on the network while
300 * older kernels had a special socket type SOCK_PACKET to
301 * implement this feature.
302 * While this old implementation is kind of obsolete we need
303 * to be compatible with older kernels for a while so we are
304 * trying both methods with the newer method preferred.
305 */
306
307 if ((err = live_open_new(handle, device, promisc, to_ms, ebuf)) == 1)
308 live_open_ok = 1;
309 else if (err == 0) {
310 /* Non-fatal error; try old way */
311 if (live_open_old(handle, device, promisc, to_ms, ebuf))
312 live_open_ok = 1;
313 }
314 if (!live_open_ok) {
315 /*
316 * Both methods to open the packet socket failed. Tidy
317 * up and report our failure (ebuf is expected to be
318 * set by the functions above).
319 */
320
321 if (handle->md.device != NULL)
322 free(handle->md.device);
323 free(handle);
324 return NULL;
325 }
326
327 /*
328 * Compute the buffer size.
329 *
330 * If we're using SOCK_PACKET, this might be a 2.0[.x] kernel,
331 * and might require special handling - check.
332 */
333 if (handle->md.sock_packet && (uname(&utsname) < 0 ||
334 strncmp(utsname.release, "2.0", 3) == 0)) {
335 /*
336 * We're using a SOCK_PACKET structure, and either
337 * we couldn't find out what kernel release this is,
338 * or it's a 2.0[.x] kernel.
339 *
340 * In the 2.0[.x] kernel, a "recvfrom()" on
341 * a SOCK_PACKET socket, with MSG_TRUNC set, will
342 * return the number of bytes read, so if we pass
343 * a length based on the snapshot length, it'll
344 * return the number of bytes from the packet
345 * copied to userland, not the actual length
346 * of the packet.
347 *
348 * This means that, for example, the IP dissector
349 * in tcpdump will get handed a packet length less
350 * than the length in the IP header, and will
351 * complain about "truncated-ip".
352 *
353 * So we don't bother trying to copy from the
354 * kernel only the bytes in which we're interested,
355 * but instead copy them all, just as the older
356 * versions of libpcap for Linux did.
357 *
358 * The buffer therefore needs to be big enough to
359 * hold the largest packet we can get from this
360 * device. Unfortunately, we can't get the MRU
361 * of the network; we can only get the MTU. The
362 * MTU may be too small, in which case a packet larger
363 * than the buffer size will be truncated *and* we
364 * won't get the actual packet size.
365 *
366 * However, if the snapshot length is larger than
367 * the buffer size based on the MTU, we use the
368 * snapshot length as the buffer size, instead;
369 * this means that with a sufficiently large snapshot
370 * length we won't artificially truncate packets
371 * to the MTU-based size.
372 *
373 * This mess just one of many problems with packet
374 * capture on 2.0[.x] kernels; you really want a
375 * 2.2[.x] or later kernel if you want packet capture
376 * to work well.
377 */
378 mtu = iface_get_mtu(handle->fd, device, ebuf);
379 if (mtu == -1) {
380 pcap_close_linux(handle);
381 free(handle);
382 return NULL;
383 }
384 handle->bufsize = MAX_LINKHEADER_SIZE + mtu;
385 if (handle->bufsize < handle->snapshot)
386 handle->bufsize = handle->snapshot;
387 } else {
388 /*
389 * This is a 2.2[.x] or later kernel (we know that
390 * either because we're not using a SOCK_PACKET
391 * socket - PF_PACKET is supported only in 2.2
392 * and later kernels - or because we checked the
393 * kernel version).
394 *
395 * We can safely pass "recvfrom()" a byte count
396 * based on the snapshot length.
| 31#endif
32
33/*
34 * Known problems with 2.0[.x] kernels:
35 *
36 * - The loopback device gives every packet twice; on 2.2[.x] kernels,
37 * if we use PF_PACKET, we can filter out the transmitted version
38 * of the packet by using data in the "sockaddr_ll" returned by
39 * "recvfrom()", but, on 2.0[.x] kernels, we have to use
40 * PF_INET/SOCK_PACKET, which means "recvfrom()" supplies a
41 * "sockaddr_pkt" which doesn't give us enough information to let
42 * us do that.
43 *
44 * - We have to set the interface's IFF_PROMISC flag ourselves, if
45 * we're to run in promiscuous mode, which means we have to turn
46 * it off ourselves when we're done; the kernel doesn't keep track
47 * of how many sockets are listening promiscuously, which means
48 * it won't get turned off automatically when no sockets are
49 * listening promiscuously. We catch "pcap_close()" and, for
50 * interfaces we put into promiscuous mode, take them out of
51 * promiscuous mode - which isn't necessarily the right thing to
52 * do, if another socket also requested promiscuous mode between
53 * the time when we opened the socket and the time when we close
54 * the socket.
55 *
56 * - MSG_TRUNC isn't supported, so you can't specify that "recvfrom()"
57 * return the amount of data that you could have read, rather than
58 * the amount that was returned, so we can't just allocate a buffer
59 * whose size is the snapshot length and pass the snapshot length
60 * as the byte count, and also pass MSG_TRUNC, so that the return
61 * value tells us how long the packet was on the wire.
62 *
63 * This means that, if we want to get the actual size of the packet,
64 * so we can return it in the "len" field of the packet header,
65 * we have to read the entire packet, not just the part that fits
66 * within the snapshot length, and thus waste CPU time copying data
67 * from the kernel that our caller won't see.
68 *
69 * We have to get the actual size, and supply it in "len", because
70 * otherwise, the IP dissector in tcpdump, for example, will complain
71 * about "truncated-ip", as the packet will appear to have been
72 * shorter, on the wire, than the IP header said it should have been.
73 */
74
75
76#ifdef HAVE_CONFIG_H
77#include "config.h"
78#endif
79
80#include "pcap-int.h"
81#include "sll.h"
82
83#ifdef HAVE_DAG_API
84#include "pcap-dag.h"
85#endif /* HAVE_DAG_API */
86
87#ifdef HAVE_SEPTEL_API
88#include "pcap-septel.h"
89#endif /* HAVE_SEPTEL_API */
90
91#include <errno.h>
92#include <stdlib.h>
93#include <unistd.h>
94#include <fcntl.h>
95#include <string.h>
96#include <sys/socket.h>
97#include <sys/ioctl.h>
98#include <sys/utsname.h>
99#include <net/if.h>
100#include <netinet/in.h>
101#include <linux/if_ether.h>
102#include <net/if_arp.h>
103
104/*
105 * If PF_PACKET is defined, we can use {SOCK_RAW,SOCK_DGRAM}/PF_PACKET
106 * sockets rather than SOCK_PACKET sockets.
107 *
108 * To use them, we include <linux/if_packet.h> rather than
109 * <netpacket/packet.h>; we do so because
110 *
111 * some Linux distributions (e.g., Slackware 4.0) have 2.2 or
112 * later kernels and libc5, and don't provide a <netpacket/packet.h>
113 * file;
114 *
115 * not all versions of glibc2 have a <netpacket/packet.h> file
116 * that defines stuff needed for some of the 2.4-or-later-kernel
117 * features, so if the system has a 2.4 or later kernel, we
118 * still can't use those features.
119 *
120 * We're already including a number of other <linux/XXX.h> headers, and
121 * this code is Linux-specific (no other OS has PF_PACKET sockets as
122 * a raw packet capture mechanism), so it's not as if you gain any
123 * useful portability by using <netpacket/packet.h>
124 *
125 * XXX - should we just include <linux/if_packet.h> even if PF_PACKET
126 * isn't defined? It only defines one data structure in 2.0.x, so
127 * it shouldn't cause any problems.
128 */
129#ifdef PF_PACKET
130# include <linux/if_packet.h>
131
132 /*
133 * On at least some Linux distributions (for example, Red Hat 5.2),
134 * there's no <netpacket/packet.h> file, but PF_PACKET is defined if
135 * you include <sys/socket.h>, but <linux/if_packet.h> doesn't define
136 * any of the PF_PACKET stuff such as "struct sockaddr_ll" or any of
137 * the PACKET_xxx stuff.
138 *
139 * So we check whether PACKET_HOST is defined, and assume that we have
140 * PF_PACKET sockets only if it is defined.
141 */
142# ifdef PACKET_HOST
143# define HAVE_PF_PACKET_SOCKETS
144# endif /* PACKET_HOST */
145#endif /* PF_PACKET */
146
147#ifdef SO_ATTACH_FILTER
148#include <linux/types.h>
149#include <linux/filter.h>
150#endif
151
152#ifndef __GLIBC__
153typedef int socklen_t;
154#endif
155
156#ifndef MSG_TRUNC
157/*
158 * This is being compiled on a system that lacks MSG_TRUNC; define it
159 * with the value it has in the 2.2 and later kernels, so that, on
160 * those kernels, when we pass it in the flags argument to "recvfrom()"
161 * we're passing the right value and thus get the MSG_TRUNC behavior
162 * we want. (We don't get that behavior on 2.0[.x] kernels, because
163 * they didn't support MSG_TRUNC.)
164 */
165#define MSG_TRUNC 0x20
166#endif
167
168#ifndef SOL_PACKET
169/*
170 * This is being compiled on a system that lacks SOL_PACKET; define it
171 * with the value it has in the 2.2 and later kernels, so that we can
172 * set promiscuous mode in the good modern way rather than the old
173 * 2.0-kernel crappy way.
174 */
175#define SOL_PACKET 263
176#endif
177
178#define MAX_LINKHEADER_SIZE 256
179
180/*
181 * When capturing on all interfaces we use this as the buffer size.
182 * Should be bigger then all MTUs that occur in real life.
183 * 64kB should be enough for now.
184 */
185#define BIGGER_THAN_ALL_MTUS (64*1024)
186
187/*
188 * Prototypes for internal functions
189 */
190static void map_arphrd_to_dlt(pcap_t *, int, int);
191static int live_open_old(pcap_t *, const char *, int, int, char *);
192static int live_open_new(pcap_t *, const char *, int, int, char *);
193static int pcap_read_linux(pcap_t *, int, pcap_handler, u_char *);
194static int pcap_read_packet(pcap_t *, pcap_handler, u_char *);
195static int pcap_inject_linux(pcap_t *, const void *, size_t);
196static int pcap_stats_linux(pcap_t *, struct pcap_stat *);
197static int pcap_setfilter_linux(pcap_t *, struct bpf_program *);
198static int pcap_setdirection_linux(pcap_t *, pcap_direction_t);
199static void pcap_close_linux(pcap_t *);
200
201/*
202 * Wrap some ioctl calls
203 */
204#ifdef HAVE_PF_PACKET_SOCKETS
205static int iface_get_id(int fd, const char *device, char *ebuf);
206#endif
207static int iface_get_mtu(int fd, const char *device, char *ebuf);
208static int iface_get_arptype(int fd, const char *device, char *ebuf);
209#ifdef HAVE_PF_PACKET_SOCKETS
210static int iface_bind(int fd, int ifindex, char *ebuf);
211#endif
212static int iface_bind_old(int fd, const char *device, char *ebuf);
213
214#ifdef SO_ATTACH_FILTER
215static int fix_program(pcap_t *handle, struct sock_fprog *fcode);
216static int fix_offset(struct bpf_insn *p);
217static int set_kernel_filter(pcap_t *handle, struct sock_fprog *fcode);
218static int reset_kernel_filter(pcap_t *handle);
219
220static struct sock_filter total_insn
221 = BPF_STMT(BPF_RET | BPF_K, 0);
222static struct sock_fprog total_fcode
223 = { 1, &total_insn };
224#endif
225
226/*
227 * Get a handle for a live capture from the given device. You can
228 * pass NULL as device to get all packages (without link level
229 * information of course). If you pass 1 as promisc the interface
230 * will be set to promiscous mode (XXX: I think this usage should
231 * be deprecated and functions be added to select that later allow
232 * modification of that values -- Torsten).
233 *
234 * See also pcap(3).
235 */
236pcap_t *
237pcap_open_live(const char *device, int snaplen, int promisc, int to_ms,
238 char *ebuf)
239{
240 pcap_t *handle;
241 int mtu;
242 int err;
243 int live_open_ok = 0;
244 struct utsname utsname;
245
246#ifdef HAVE_DAG_API
247 if (strstr(device, "dag")) {
248 return dag_open_live(device, snaplen, promisc, to_ms, ebuf);
249 }
250#endif /* HAVE_DAG_API */
251
252#ifdef HAVE_SEPTEL_API
253 if (strstr(device, "septel")) {
254 return septel_open_live(device, snaplen, promisc, to_ms, ebuf);
255 }
256#endif /* HAVE_SEPTEL_API */
257
258 /* Allocate a handle for this session. */
259
260 handle = malloc(sizeof(*handle));
261 if (handle == NULL) {
262 snprintf(ebuf, PCAP_ERRBUF_SIZE, "malloc: %s",
263 pcap_strerror(errno));
264 return NULL;
265 }
266
267 /* Initialize some components of the pcap structure. */
268
269 memset(handle, 0, sizeof(*handle));
270 handle->snapshot = snaplen;
271 handle->md.timeout = to_ms;
272
273 /*
274 * NULL and "any" are special devices which give us the hint to
275 * monitor all devices.
276 */
277 if (!device || strcmp(device, "any") == 0) {
278 device = NULL;
279 handle->md.device = strdup("any");
280 if (promisc) {
281 promisc = 0;
282 /* Just a warning. */
283 snprintf(ebuf, PCAP_ERRBUF_SIZE,
284 "Promiscuous mode not supported on the \"any\" device");
285 }
286
287 } else
288 handle->md.device = strdup(device);
289
290 if (handle->md.device == NULL) {
291 snprintf(ebuf, PCAP_ERRBUF_SIZE, "strdup: %s",
292 pcap_strerror(errno) );
293 free(handle);
294 return NULL;
295 }
296
297 /*
298 * Current Linux kernels use the protocol family PF_PACKET to
299 * allow direct access to all packets on the network while
300 * older kernels had a special socket type SOCK_PACKET to
301 * implement this feature.
302 * While this old implementation is kind of obsolete we need
303 * to be compatible with older kernels for a while so we are
304 * trying both methods with the newer method preferred.
305 */
306
307 if ((err = live_open_new(handle, device, promisc, to_ms, ebuf)) == 1)
308 live_open_ok = 1;
309 else if (err == 0) {
310 /* Non-fatal error; try old way */
311 if (live_open_old(handle, device, promisc, to_ms, ebuf))
312 live_open_ok = 1;
313 }
314 if (!live_open_ok) {
315 /*
316 * Both methods to open the packet socket failed. Tidy
317 * up and report our failure (ebuf is expected to be
318 * set by the functions above).
319 */
320
321 if (handle->md.device != NULL)
322 free(handle->md.device);
323 free(handle);
324 return NULL;
325 }
326
327 /*
328 * Compute the buffer size.
329 *
330 * If we're using SOCK_PACKET, this might be a 2.0[.x] kernel,
331 * and might require special handling - check.
332 */
333 if (handle->md.sock_packet && (uname(&utsname) < 0 ||
334 strncmp(utsname.release, "2.0", 3) == 0)) {
335 /*
336 * We're using a SOCK_PACKET structure, and either
337 * we couldn't find out what kernel release this is,
338 * or it's a 2.0[.x] kernel.
339 *
340 * In the 2.0[.x] kernel, a "recvfrom()" on
341 * a SOCK_PACKET socket, with MSG_TRUNC set, will
342 * return the number of bytes read, so if we pass
343 * a length based on the snapshot length, it'll
344 * return the number of bytes from the packet
345 * copied to userland, not the actual length
346 * of the packet.
347 *
348 * This means that, for example, the IP dissector
349 * in tcpdump will get handed a packet length less
350 * than the length in the IP header, and will
351 * complain about "truncated-ip".
352 *
353 * So we don't bother trying to copy from the
354 * kernel only the bytes in which we're interested,
355 * but instead copy them all, just as the older
356 * versions of libpcap for Linux did.
357 *
358 * The buffer therefore needs to be big enough to
359 * hold the largest packet we can get from this
360 * device. Unfortunately, we can't get the MRU
361 * of the network; we can only get the MTU. The
362 * MTU may be too small, in which case a packet larger
363 * than the buffer size will be truncated *and* we
364 * won't get the actual packet size.
365 *
366 * However, if the snapshot length is larger than
367 * the buffer size based on the MTU, we use the
368 * snapshot length as the buffer size, instead;
369 * this means that with a sufficiently large snapshot
370 * length we won't artificially truncate packets
371 * to the MTU-based size.
372 *
373 * This mess just one of many problems with packet
374 * capture on 2.0[.x] kernels; you really want a
375 * 2.2[.x] or later kernel if you want packet capture
376 * to work well.
377 */
378 mtu = iface_get_mtu(handle->fd, device, ebuf);
379 if (mtu == -1) {
380 pcap_close_linux(handle);
381 free(handle);
382 return NULL;
383 }
384 handle->bufsize = MAX_LINKHEADER_SIZE + mtu;
385 if (handle->bufsize < handle->snapshot)
386 handle->bufsize = handle->snapshot;
387 } else {
388 /*
389 * This is a 2.2[.x] or later kernel (we know that
390 * either because we're not using a SOCK_PACKET
391 * socket - PF_PACKET is supported only in 2.2
392 * and later kernels - or because we checked the
393 * kernel version).
394 *
395 * We can safely pass "recvfrom()" a byte count
396 * based on the snapshot length.
|
| 397 *
398 * If we're in cooked mode, make the snapshot length
399 * large enough to hold a "cooked mode" header plus
400 * 1 byte of packet data (so we don't pass a byte
401 * count of 0 to "recvfrom()").
|
397 */
| 402 */
|
| 403 if (handle->md.cooked) {
404 if (handle->snapshot < SLL_HDR_LEN + 1)
405 handle->snapshot = SLL_HDR_LEN + 1;
406 }
|
398 handle->bufsize = handle->snapshot;
399 }
400
401 /* Allocate the buffer */
402
403 handle->buffer = malloc(handle->bufsize + handle->offset);
404 if (!handle->buffer) {
405 snprintf(ebuf, PCAP_ERRBUF_SIZE,
406 "malloc: %s", pcap_strerror(errno));
407 pcap_close_linux(handle);
408 free(handle);
409 return NULL;
410 }
411
412 /*
413 * "handle->fd" is a socket, so "select()" and "poll()"
414 * should work on it.
415 */
416 handle->selectable_fd = handle->fd;
417
418 handle->read_op = pcap_read_linux;
419 handle->inject_op = pcap_inject_linux;
420 handle->setfilter_op = pcap_setfilter_linux;
421 handle->setdirection_op = pcap_setdirection_linux;
422 handle->set_datalink_op = NULL; /* can't change data link type */
423 handle->getnonblock_op = pcap_getnonblock_fd;
424 handle->setnonblock_op = pcap_setnonblock_fd;
425 handle->stats_op = pcap_stats_linux;
426 handle->close_op = pcap_close_linux;
427
428 return handle;
429}
430
431/*
432 * Read at most max_packets from the capture stream and call the callback
433 * for each of them. Returns the number of packets handled or -1 if an
434 * error occured.
435 */
436static int
437pcap_read_linux(pcap_t *handle, int max_packets, pcap_handler callback, u_char *user)
438{
439 /*
440 * Currently, on Linux only one packet is delivered per read,
441 * so we don't loop.
442 */
443 return pcap_read_packet(handle, callback, user);
444}
445
446/*
447 * Read a packet from the socket calling the handler provided by
448 * the user. Returns the number of packets received or -1 if an
449 * error occured.
450 */
451static int
452pcap_read_packet(pcap_t *handle, pcap_handler callback, u_char *userdata)
453{
454 u_char *bp;
455 int offset;
456#ifdef HAVE_PF_PACKET_SOCKETS
457 struct sockaddr_ll from;
458 struct sll_header *hdrp;
459#else
460 struct sockaddr from;
461#endif
462 socklen_t fromlen;
463 int packet_len, caplen;
464 struct pcap_pkthdr pcap_header;
465
466#ifdef HAVE_PF_PACKET_SOCKETS
467 /*
468 * If this is a cooked device, leave extra room for a
469 * fake packet header.
470 */
471 if (handle->md.cooked)
472 offset = SLL_HDR_LEN;
473 else
474 offset = 0;
475#else
476 /*
477 * This system doesn't have PF_PACKET sockets, so it doesn't
478 * support cooked devices.
479 */
480 offset = 0;
481#endif
482
483 /* Receive a single packet from the kernel */
484
485 bp = handle->buffer + handle->offset;
486 do {
487 /*
488 * Has "pcap_breakloop()" been called?
489 */
490 if (handle->break_loop) {
491 /*
492 * Yes - clear the flag that indicates that it
493 * has, and return -2 as an indication that we
494 * were told to break out of the loop.
495 */
496 handle->break_loop = 0;
497 return -2;
498 }
499 fromlen = sizeof(from);
500 packet_len = recvfrom(
501 handle->fd, bp + offset,
502 handle->bufsize - offset, MSG_TRUNC,
503 (struct sockaddr *) &from, &fromlen);
504 } while (packet_len == -1 && errno == EINTR);
505
506 /* Check if an error occured */
507
508 if (packet_len == -1) {
509 if (errno == EAGAIN)
510 return 0; /* no packet there */
511 else {
512 snprintf(handle->errbuf, sizeof(handle->errbuf),
513 "recvfrom: %s", pcap_strerror(errno));
514 return -1;
515 }
516 }
517
518#ifdef HAVE_PF_PACKET_SOCKETS
519 if (!handle->md.sock_packet) {
520 /*
| 407 handle->bufsize = handle->snapshot;
408 }
409
410 /* Allocate the buffer */
411
412 handle->buffer = malloc(handle->bufsize + handle->offset);
413 if (!handle->buffer) {
414 snprintf(ebuf, PCAP_ERRBUF_SIZE,
415 "malloc: %s", pcap_strerror(errno));
416 pcap_close_linux(handle);
417 free(handle);
418 return NULL;
419 }
420
421 /*
422 * "handle->fd" is a socket, so "select()" and "poll()"
423 * should work on it.
424 */
425 handle->selectable_fd = handle->fd;
426
427 handle->read_op = pcap_read_linux;
428 handle->inject_op = pcap_inject_linux;
429 handle->setfilter_op = pcap_setfilter_linux;
430 handle->setdirection_op = pcap_setdirection_linux;
431 handle->set_datalink_op = NULL; /* can't change data link type */
432 handle->getnonblock_op = pcap_getnonblock_fd;
433 handle->setnonblock_op = pcap_setnonblock_fd;
434 handle->stats_op = pcap_stats_linux;
435 handle->close_op = pcap_close_linux;
436
437 return handle;
438}
439
440/*
441 * Read at most max_packets from the capture stream and call the callback
442 * for each of them. Returns the number of packets handled or -1 if an
443 * error occured.
444 */
445static int
446pcap_read_linux(pcap_t *handle, int max_packets, pcap_handler callback, u_char *user)
447{
448 /*
449 * Currently, on Linux only one packet is delivered per read,
450 * so we don't loop.
451 */
452 return pcap_read_packet(handle, callback, user);
453}
454
455/*
456 * Read a packet from the socket calling the handler provided by
457 * the user. Returns the number of packets received or -1 if an
458 * error occured.
459 */
460static int
461pcap_read_packet(pcap_t *handle, pcap_handler callback, u_char *userdata)
462{
463 u_char *bp;
464 int offset;
465#ifdef HAVE_PF_PACKET_SOCKETS
466 struct sockaddr_ll from;
467 struct sll_header *hdrp;
468#else
469 struct sockaddr from;
470#endif
471 socklen_t fromlen;
472 int packet_len, caplen;
473 struct pcap_pkthdr pcap_header;
474
475#ifdef HAVE_PF_PACKET_SOCKETS
476 /*
477 * If this is a cooked device, leave extra room for a
478 * fake packet header.
479 */
480 if (handle->md.cooked)
481 offset = SLL_HDR_LEN;
482 else
483 offset = 0;
484#else
485 /*
486 * This system doesn't have PF_PACKET sockets, so it doesn't
487 * support cooked devices.
488 */
489 offset = 0;
490#endif
491
492 /* Receive a single packet from the kernel */
493
494 bp = handle->buffer + handle->offset;
495 do {
496 /*
497 * Has "pcap_breakloop()" been called?
498 */
499 if (handle->break_loop) {
500 /*
501 * Yes - clear the flag that indicates that it
502 * has, and return -2 as an indication that we
503 * were told to break out of the loop.
504 */
505 handle->break_loop = 0;
506 return -2;
507 }
508 fromlen = sizeof(from);
509 packet_len = recvfrom(
510 handle->fd, bp + offset,
511 handle->bufsize - offset, MSG_TRUNC,
512 (struct sockaddr *) &from, &fromlen);
513 } while (packet_len == -1 && errno == EINTR);
514
515 /* Check if an error occured */
516
517 if (packet_len == -1) {
518 if (errno == EAGAIN)
519 return 0; /* no packet there */
520 else {
521 snprintf(handle->errbuf, sizeof(handle->errbuf),
522 "recvfrom: %s", pcap_strerror(errno));
523 return -1;
524 }
525 }
526
527#ifdef HAVE_PF_PACKET_SOCKETS
528 if (!handle->md.sock_packet) {
529 /*
|
| 530 * Unfortunately, there is a window between socket() and
531 * bind() where the kernel may queue packets from any
532 * interface. If we're bound to a particular interface,
533 * discard packets not from that interface.
534 *
535 * (If socket filters are supported, we could do the
536 * same thing we do when changing the filter; however,
537 * that won't handle packet sockets without socket
538 * filter support, and it's a bit more complicated.
539 * It would save some instructions per packet, however.)
540 */
541 if (handle->md.ifindex != -1 &&
542 from.sll_ifindex != handle->md.ifindex)
543 return 0;
544
545 /*
|
521 * Do checks based on packet direction.
522 * We can only do this if we're using PF_PACKET; the
523 * address returned for SOCK_PACKET is a "sockaddr_pkt"
524 * which lacks the relevant packet type information.
525 */
526 if (from.sll_pkttype == PACKET_OUTGOING) {
527 /*
528 * Outgoing packet.
529 * If this is from the loopback device, reject it;
530 * we'll see the packet as an incoming packet as well,
531 * and we don't want to see it twice.
532 */
533 if (from.sll_ifindex == handle->md.lo_ifindex)
534 return 0;
535
536 /*
537 * If the user only wants incoming packets, reject it.
538 */
539 if (handle->direction == PCAP_D_IN)
540 return 0;
541 } else {
542 /*
543 * Incoming packet.
544 * If the user only wants outgoing packets, reject it.
545 */
546 if (handle->direction == PCAP_D_OUT)
547 return 0;
548 }
549 }
550#endif
551
552#ifdef HAVE_PF_PACKET_SOCKETS
553 /*
554 * If this is a cooked device, fill in the fake packet header.
555 */
556 if (handle->md.cooked) {
557 /*
558 * Add the length of the fake header to the length
559 * of packet data we read.
560 */
561 packet_len += SLL_HDR_LEN;
562
563 hdrp = (struct sll_header *)bp;
564
565 /*
566 * Map the PACKET_ value to a LINUX_SLL_ value; we
567 * want the same numerical value to be used in
568 * the link-layer header even if the numerical values
569 * for the PACKET_ #defines change, so that programs
570 * that look at the packet type field will always be
571 * able to handle DLT_LINUX_SLL captures.
572 */
573 switch (from.sll_pkttype) {
574
575 case PACKET_HOST:
576 hdrp->sll_pkttype = htons(LINUX_SLL_HOST);
577 break;
578
579 case PACKET_BROADCAST:
580 hdrp->sll_pkttype = htons(LINUX_SLL_BROADCAST);
581 break;
582
583 case PACKET_MULTICAST:
584 hdrp->sll_pkttype = htons(LINUX_SLL_MULTICAST);
585 break;
586
587 case PACKET_OTHERHOST:
588 hdrp->sll_pkttype = htons(LINUX_SLL_OTHERHOST);
589 break;
590
591 case PACKET_OUTGOING:
592 hdrp->sll_pkttype = htons(LINUX_SLL_OUTGOING);
593 break;
594
595 default:
596 hdrp->sll_pkttype = -1;
597 break;
598 }
599
600 hdrp->sll_hatype = htons(from.sll_hatype);
601 hdrp->sll_halen = htons(from.sll_halen);
602 memcpy(hdrp->sll_addr, from.sll_addr,
603 (from.sll_halen > SLL_ADDRLEN) ?
604 SLL_ADDRLEN :
605 from.sll_halen);
606 hdrp->sll_protocol = from.sll_protocol;
607 }
608#endif
609
610 /*
611 * XXX: According to the kernel source we should get the real
612 * packet len if calling recvfrom with MSG_TRUNC set. It does
613 * not seem to work here :(, but it is supported by this code
614 * anyway.
615 * To be honest the code RELIES on that feature so this is really
616 * broken with 2.2.x kernels.
617 * I spend a day to figure out what's going on and I found out
618 * that the following is happening:
619 *
620 * The packet comes from a random interface and the packet_rcv
621 * hook is called with a clone of the packet. That code inserts
622 * the packet into the receive queue of the packet socket.
623 * If a filter is attached to that socket that filter is run
624 * first - and there lies the problem. The default filter always
625 * cuts the packet at the snaplen:
626 *
627 * # tcpdump -d
628 * (000) ret #68
629 *
630 * So the packet filter cuts down the packet. The recvfrom call
631 * says "hey, it's only 68 bytes, it fits into the buffer" with
632 * the result that we don't get the real packet length. This
633 * is valid at least until kernel 2.2.17pre6.
634 *
635 * We currently handle this by making a copy of the filter
636 * program, fixing all "ret" instructions with non-zero
637 * operands to have an operand of 65535 so that the filter
638 * doesn't truncate the packet, and supplying that modified
639 * filter to the kernel.
640 */
641
642 caplen = packet_len;
643 if (caplen > handle->snapshot)
644 caplen = handle->snapshot;
645
646 /* Run the packet filter if not using kernel filter */
647 if (!handle->md.use_bpf && handle->fcode.bf_insns) {
648 if (bpf_filter(handle->fcode.bf_insns, bp,
649 packet_len, caplen) == 0)
650 {
651 /* rejected by filter */
652 return 0;
653 }
654 }
655
656 /* Fill in our own header data */
657
658 if (ioctl(handle->fd, SIOCGSTAMP, &pcap_header.ts) == -1) {
659 snprintf(handle->errbuf, sizeof(handle->errbuf),
| 546 * Do checks based on packet direction.
547 * We can only do this if we're using PF_PACKET; the
548 * address returned for SOCK_PACKET is a "sockaddr_pkt"
549 * which lacks the relevant packet type information.
550 */
551 if (from.sll_pkttype == PACKET_OUTGOING) {
552 /*
553 * Outgoing packet.
554 * If this is from the loopback device, reject it;
555 * we'll see the packet as an incoming packet as well,
556 * and we don't want to see it twice.
557 */
558 if (from.sll_ifindex == handle->md.lo_ifindex)
559 return 0;
560
561 /*
562 * If the user only wants incoming packets, reject it.
563 */
564 if (handle->direction == PCAP_D_IN)
565 return 0;
566 } else {
567 /*
568 * Incoming packet.
569 * If the user only wants outgoing packets, reject it.
570 */
571 if (handle->direction == PCAP_D_OUT)
572 return 0;
573 }
574 }
575#endif
576
577#ifdef HAVE_PF_PACKET_SOCKETS
578 /*
579 * If this is a cooked device, fill in the fake packet header.
580 */
581 if (handle->md.cooked) {
582 /*
583 * Add the length of the fake header to the length
584 * of packet data we read.
585 */
586 packet_len += SLL_HDR_LEN;
587
588 hdrp = (struct sll_header *)bp;
589
590 /*
591 * Map the PACKET_ value to a LINUX_SLL_ value; we
592 * want the same numerical value to be used in
593 * the link-layer header even if the numerical values
594 * for the PACKET_ #defines change, so that programs
595 * that look at the packet type field will always be
596 * able to handle DLT_LINUX_SLL captures.
597 */
598 switch (from.sll_pkttype) {
599
600 case PACKET_HOST:
601 hdrp->sll_pkttype = htons(LINUX_SLL_HOST);
602 break;
603
604 case PACKET_BROADCAST:
605 hdrp->sll_pkttype = htons(LINUX_SLL_BROADCAST);
606 break;
607
608 case PACKET_MULTICAST:
609 hdrp->sll_pkttype = htons(LINUX_SLL_MULTICAST);
610 break;
611
612 case PACKET_OTHERHOST:
613 hdrp->sll_pkttype = htons(LINUX_SLL_OTHERHOST);
614 break;
615
616 case PACKET_OUTGOING:
617 hdrp->sll_pkttype = htons(LINUX_SLL_OUTGOING);
618 break;
619
620 default:
621 hdrp->sll_pkttype = -1;
622 break;
623 }
624
625 hdrp->sll_hatype = htons(from.sll_hatype);
626 hdrp->sll_halen = htons(from.sll_halen);
627 memcpy(hdrp->sll_addr, from.sll_addr,
628 (from.sll_halen > SLL_ADDRLEN) ?
629 SLL_ADDRLEN :
630 from.sll_halen);
631 hdrp->sll_protocol = from.sll_protocol;
632 }
633#endif
634
635 /*
636 * XXX: According to the kernel source we should get the real
637 * packet len if calling recvfrom with MSG_TRUNC set. It does
638 * not seem to work here :(, but it is supported by this code
639 * anyway.
640 * To be honest the code RELIES on that feature so this is really
641 * broken with 2.2.x kernels.
642 * I spend a day to figure out what's going on and I found out
643 * that the following is happening:
644 *
645 * The packet comes from a random interface and the packet_rcv
646 * hook is called with a clone of the packet. That code inserts
647 * the packet into the receive queue of the packet socket.
648 * If a filter is attached to that socket that filter is run
649 * first - and there lies the problem. The default filter always
650 * cuts the packet at the snaplen:
651 *
652 * # tcpdump -d
653 * (000) ret #68
654 *
655 * So the packet filter cuts down the packet. The recvfrom call
656 * says "hey, it's only 68 bytes, it fits into the buffer" with
657 * the result that we don't get the real packet length. This
658 * is valid at least until kernel 2.2.17pre6.
659 *
660 * We currently handle this by making a copy of the filter
661 * program, fixing all "ret" instructions with non-zero
662 * operands to have an operand of 65535 so that the filter
663 * doesn't truncate the packet, and supplying that modified
664 * filter to the kernel.
665 */
666
667 caplen = packet_len;
668 if (caplen > handle->snapshot)
669 caplen = handle->snapshot;
670
671 /* Run the packet filter if not using kernel filter */
672 if (!handle->md.use_bpf && handle->fcode.bf_insns) {
673 if (bpf_filter(handle->fcode.bf_insns, bp,
674 packet_len, caplen) == 0)
675 {
676 /* rejected by filter */
677 return 0;
678 }
679 }
680
681 /* Fill in our own header data */
682
683 if (ioctl(handle->fd, SIOCGSTAMP, &pcap_header.ts) == -1) {
684 snprintf(handle->errbuf, sizeof(handle->errbuf),
|
660 "ioctl: %s", pcap_strerror(errno));
| 685 "SIOCGSTAMP: %s", pcap_strerror(errno));
|
661 return -1;
662 }
663 pcap_header.caplen = caplen;
664 pcap_header.len = packet_len;
665
666 /*
667 * Count the packet.
668 *
669 * Arguably, we should count them before we check the filter,
670 * as on many other platforms "ps_recv" counts packets
671 * handed to the filter rather than packets that passed
672 * the filter, but if filtering is done in the kernel, we
673 * can't get a count of packets that passed the filter,
674 * and that would mean the meaning of "ps_recv" wouldn't
675 * be the same on all Linux systems.
676 *
677 * XXX - it's not the same on all systems in any case;
678 * ideally, we should have a "get the statistics" call
679 * that supplies more counts and indicates which of them
680 * it supplies, so that we supply a count of packets
681 * handed to the filter only on platforms where that
682 * information is available.
683 *
684 * We count them here even if we can get the packet count
685 * from the kernel, as we can only determine at run time
686 * whether we'll be able to get it from the kernel (if
687 * HAVE_TPACKET_STATS isn't defined, we can't get it from
688 * the kernel, but if it is defined, the library might
689 * have been built with a 2.4 or later kernel, but we
690 * might be running on a 2.2[.x] kernel without Alexey
691 * Kuznetzov's turbopacket patches, and thus the kernel
692 * might not be able to supply those statistics). We
693 * could, I guess, try, when opening the socket, to get
694 * the statistics, and if we can not increment the count
695 * here, but it's not clear that always incrementing
696 * the count is more expensive than always testing a flag
697 * in memory.
| 686 return -1;
687 }
688 pcap_header.caplen = caplen;
689 pcap_header.len = packet_len;
690
691 /*
692 * Count the packet.
693 *
694 * Arguably, we should count them before we check the filter,
695 * as on many other platforms "ps_recv" counts packets
696 * handed to the filter rather than packets that passed
697 * the filter, but if filtering is done in the kernel, we
698 * can't get a count of packets that passed the filter,
699 * and that would mean the meaning of "ps_recv" wouldn't
700 * be the same on all Linux systems.
701 *
702 * XXX - it's not the same on all systems in any case;
703 * ideally, we should have a "get the statistics" call
704 * that supplies more counts and indicates which of them
705 * it supplies, so that we supply a count of packets
706 * handed to the filter only on platforms where that
707 * information is available.
708 *
709 * We count them here even if we can get the packet count
710 * from the kernel, as we can only determine at run time
711 * whether we'll be able to get it from the kernel (if
712 * HAVE_TPACKET_STATS isn't defined, we can't get it from
713 * the kernel, but if it is defined, the library might
714 * have been built with a 2.4 or later kernel, but we
715 * might be running on a 2.2[.x] kernel without Alexey
716 * Kuznetzov's turbopacket patches, and thus the kernel
717 * might not be able to supply those statistics). We
718 * could, I guess, try, when opening the socket, to get
719 * the statistics, and if we can not increment the count
720 * here, but it's not clear that always incrementing
721 * the count is more expensive than always testing a flag
722 * in memory.
|
| 723 *
724 * We keep the count in "md.packets_read", and use that for
725 * "ps_recv" if we can't get the statistics from the kernel.
726 * We do that because, if we *can* get the statistics from
727 * the kernel, we use "md.stat.ps_recv" and "md.stat.ps_drop"
728 * as running counts, as reading the statistics from the
729 * kernel resets the kernel statistics, and if we directly
730 * increment "md.stat.ps_recv" here, that means it will
731 * count packets *twice* on systems where we can get kernel
732 * statistics - once here, and once in pcap_stats_linux().
|
698 */
| 733 */
|
699 handle->md.stat.ps_recv++;
| 734 handle->md.packets_read++;
|
700
701 /* Call the user supplied callback function */
702 callback(userdata, &pcap_header, bp);
703
704 return 1;
705}
706
707static int
708pcap_inject_linux(pcap_t *handle, const void *buf, size_t size)
709{
710 int ret;
711
712#ifdef HAVE_PF_PACKET_SOCKETS
713 if (!handle->md.sock_packet) {
714 /* PF_PACKET socket */
715 if (handle->md.ifindex == -1) {
716 /*
717 * We don't support sending on the "any" device.
718 */
719 strlcpy(handle->errbuf,
720 "Sending packets isn't supported on the \"any\" device",
721 PCAP_ERRBUF_SIZE);
722 return (-1);
723 }
724
725 if (handle->md.cooked) {
726 /*
727 * We don't support sending on the "any" device.
728 *
729 * XXX - how do you send on a bound cooked-mode
730 * socket?
731 * Is a "sendto()" required there?
732 */
733 strlcpy(handle->errbuf,
734 "Sending packets isn't supported in cooked mode",
735 PCAP_ERRBUF_SIZE);
736 return (-1);
737 }
738 }
739#endif
740
741 ret = send(handle->fd, buf, size, 0);
742 if (ret == -1) {
743 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "send: %s",
744 pcap_strerror(errno));
745 return (-1);
746 }
747 return (ret);
748}
749
750/*
751 * Get the statistics for the given packet capture handle.
752 * Reports the number of dropped packets iff the kernel supports
753 * the PACKET_STATISTICS "getsockopt()" argument (2.4 and later
754 * kernels, and 2.2[.x] kernels with Alexey Kuznetzov's turbopacket
755 * patches); otherwise, that information isn't available, and we lie
756 * and report 0 as the count of dropped packets.
757 */
758static int
759pcap_stats_linux(pcap_t *handle, struct pcap_stat *stats)
760{
761#ifdef HAVE_TPACKET_STATS
762 struct tpacket_stats kstats;
763 socklen_t len = sizeof (struct tpacket_stats);
764#endif
765
766#ifdef HAVE_TPACKET_STATS
767 /*
768 * Try to get the packet counts from the kernel.
769 */
770 if (getsockopt(handle->fd, SOL_PACKET, PACKET_STATISTICS,
771 &kstats, &len) > -1) {
772 /*
| 735
736 /* Call the user supplied callback function */
737 callback(userdata, &pcap_header, bp);
738
739 return 1;
740}
741
742static int
743pcap_inject_linux(pcap_t *handle, const void *buf, size_t size)
744{
745 int ret;
746
747#ifdef HAVE_PF_PACKET_SOCKETS
748 if (!handle->md.sock_packet) {
749 /* PF_PACKET socket */
750 if (handle->md.ifindex == -1) {
751 /*
752 * We don't support sending on the "any" device.
753 */
754 strlcpy(handle->errbuf,
755 "Sending packets isn't supported on the \"any\" device",
756 PCAP_ERRBUF_SIZE);
757 return (-1);
758 }
759
760 if (handle->md.cooked) {
761 /*
762 * We don't support sending on the "any" device.
763 *
764 * XXX - how do you send on a bound cooked-mode
765 * socket?
766 * Is a "sendto()" required there?
767 */
768 strlcpy(handle->errbuf,
769 "Sending packets isn't supported in cooked mode",
770 PCAP_ERRBUF_SIZE);
771 return (-1);
772 }
773 }
774#endif
775
776 ret = send(handle->fd, buf, size, 0);
777 if (ret == -1) {
778 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "send: %s",
779 pcap_strerror(errno));
780 return (-1);
781 }
782 return (ret);
783}
784
785/*
786 * Get the statistics for the given packet capture handle.
787 * Reports the number of dropped packets iff the kernel supports
788 * the PACKET_STATISTICS "getsockopt()" argument (2.4 and later
789 * kernels, and 2.2[.x] kernels with Alexey Kuznetzov's turbopacket
790 * patches); otherwise, that information isn't available, and we lie
791 * and report 0 as the count of dropped packets.
792 */
793static int
794pcap_stats_linux(pcap_t *handle, struct pcap_stat *stats)
795{
796#ifdef HAVE_TPACKET_STATS
797 struct tpacket_stats kstats;
798 socklen_t len = sizeof (struct tpacket_stats);
799#endif
800
801#ifdef HAVE_TPACKET_STATS
802 /*
803 * Try to get the packet counts from the kernel.
804 */
805 if (getsockopt(handle->fd, SOL_PACKET, PACKET_STATISTICS,
806 &kstats, &len) > -1) {
807 /*
|
| 808 * On systems where the PACKET_STATISTICS "getsockopt()"
809 * argument is supported on PF_PACKET sockets:
810 *
811 * "ps_recv" counts only packets that *passed* the
812 * filter, not packets that didn't pass the filter.
813 * This includes packets later dropped because we
814 * ran out of buffer space.
815 *
816 * "ps_drop" counts packets dropped because we ran
817 * out of buffer space. It doesn't count packets
818 * dropped by the interface driver. It counts only
819 * packets that passed the filter.
820 *
821 * Both statistics include packets not yet read from
822 * the kernel by libpcap, and thus not yet seen by
823 * the application.
824 *
|
773 * In "linux/net/packet/af_packet.c", at least in the
774 * 2.4.9 kernel, "tp_packets" is incremented for every
775 * packet that passes the packet filter *and* is
776 * successfully queued on the socket; "tp_drops" is
777 * incremented for every packet dropped because there's
778 * not enough free space in the socket buffer.
779 *
780 * When the statistics are returned for a PACKET_STATISTICS
781 * "getsockopt()" call, "tp_drops" is added to "tp_packets",
782 * so that "tp_packets" counts all packets handed to
783 * the PF_PACKET socket, including packets dropped because
784 * there wasn't room on the socket buffer - but not
785 * including packets that didn't pass the filter.
786 *
787 * In the BSD BPF, the count of received packets is
788 * incremented for every packet handed to BPF, regardless
789 * of whether it passed the filter.
790 *
791 * We can't make "pcap_stats()" work the same on both
792 * platforms, but the best approximation is to return
793 * "tp_packets" as the count of packets and "tp_drops"
794 * as the count of drops.
795 *
796 * Keep a running total because each call to
797 * getsockopt(handle->fd, SOL_PACKET, PACKET_STATISTICS, ....
798 * resets the counters to zero.
799 */
800 handle->md.stat.ps_recv += kstats.tp_packets;
801 handle->md.stat.ps_drop += kstats.tp_drops;
| 825 * In "linux/net/packet/af_packet.c", at least in the
826 * 2.4.9 kernel, "tp_packets" is incremented for every
827 * packet that passes the packet filter *and* is
828 * successfully queued on the socket; "tp_drops" is
829 * incremented for every packet dropped because there's
830 * not enough free space in the socket buffer.
831 *
832 * When the statistics are returned for a PACKET_STATISTICS
833 * "getsockopt()" call, "tp_drops" is added to "tp_packets",
834 * so that "tp_packets" counts all packets handed to
835 * the PF_PACKET socket, including packets dropped because
836 * there wasn't room on the socket buffer - but not
837 * including packets that didn't pass the filter.
838 *
839 * In the BSD BPF, the count of received packets is
840 * incremented for every packet handed to BPF, regardless
841 * of whether it passed the filter.
842 *
843 * We can't make "pcap_stats()" work the same on both
844 * platforms, but the best approximation is to return
845 * "tp_packets" as the count of packets and "tp_drops"
846 * as the count of drops.
847 *
848 * Keep a running total because each call to
849 * getsockopt(handle->fd, SOL_PACKET, PACKET_STATISTICS, ....
850 * resets the counters to zero.
851 */
852 handle->md.stat.ps_recv += kstats.tp_packets;
853 handle->md.stat.ps_drop += kstats.tp_drops;
|
| 854 *stats = handle->md.stat;
855 return 0;
|
802 }
803 else
804 {
805 /*
806 * If the error was EOPNOTSUPP, fall through, so that
807 * if you build the library on a system with
808 * "struct tpacket_stats" and run it on a system
809 * that doesn't, it works as it does if the library
810 * is built on a system without "struct tpacket_stats".
811 */
812 if (errno != EOPNOTSUPP) {
813 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
814 "pcap_stats: %s", pcap_strerror(errno));
815 return -1;
816 }
817 }
818#endif
819 /*
820 * On systems where the PACKET_STATISTICS "getsockopt()" argument
| 856 }
857 else
858 {
859 /*
860 * If the error was EOPNOTSUPP, fall through, so that
861 * if you build the library on a system with
862 * "struct tpacket_stats" and run it on a system
863 * that doesn't, it works as it does if the library
864 * is built on a system without "struct tpacket_stats".
865 */
866 if (errno != EOPNOTSUPP) {
867 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
868 "pcap_stats: %s", pcap_strerror(errno));
869 return -1;
870 }
871 }
872#endif
873 /*
874 * On systems where the PACKET_STATISTICS "getsockopt()" argument
|
821 * is supported on PF_PACKET sockets:
822 *
823 * "ps_recv" counts only packets that *passed* the filter,
824 * not packets that didn't pass the filter. This includes
825 * packets later dropped because we ran out of buffer space.
826 *
827 * "ps_drop" counts packets dropped because we ran out of
828 * buffer space. It doesn't count packets dropped by the
829 * interface driver. It counts only packets that passed
830 * the filter.
831 *
832 * Both statistics include packets not yet read from the
833 * kernel by libpcap, and thus not yet seen by the application.
834 *
835 * On systems where the PACKET_STATISTICS "getsockopt()" argument
| |
836 * is not supported on PF_PACKET sockets:
837 *
838 * "ps_recv" counts only packets that *passed* the filter,
839 * not packets that didn't pass the filter. It does not
840 * count packets dropped because we ran out of buffer
841 * space.
842 *
843 * "ps_drop" is not supported.
844 *
845 * "ps_recv" doesn't include packets not yet read from
846 * the kernel by libpcap.
| 875 * is not supported on PF_PACKET sockets:
876 *
877 * "ps_recv" counts only packets that *passed* the filter,
878 * not packets that didn't pass the filter. It does not
879 * count packets dropped because we ran out of buffer
880 * space.
881 *
882 * "ps_drop" is not supported.
883 *
884 * "ps_recv" doesn't include packets not yet read from
885 * the kernel by libpcap.
|
| 886 *
887 * We maintain the count of packets processed by libpcap in
888 * "md.packets_read", for reasons described in the comment
889 * at the end of pcap_read_packet(). We have no idea how many
890 * packets were dropped.
|
847 */
| 891 */
|
848 *stats = handle->md.stat;
| 892 stats->ps_recv = handle->md.packets_read;
893 stats->ps_drop = 0;
|
849 return 0;
850}
851
852/*
853 * Description string for the "any" device.
854 */
855static const char any_descr[] = "Pseudo-device that captures on all interfaces";
856
857int
858pcap_platform_finddevs(pcap_if_t **alldevsp, char *errbuf)
859{
860 if (pcap_add_if(alldevsp, "any", 0, any_descr, errbuf) < 0)
861 return (-1);
862
863#ifdef HAVE_DAG_API
864 if (dag_platform_finddevs(alldevsp, errbuf) < 0)
865 return (-1);
866#endif /* HAVE_DAG_API */
867
868#ifdef HAVE_SEPTEL_API
869 if (septel_platform_finddevs(alldevsp, errbuf) < 0)
870 return (-1);
871#endif /* HAVE_SEPTEL_API */
872
873 return (0);
874}
875
876/*
877 * Attach the given BPF code to the packet capture device.
878 */
879static int
880pcap_setfilter_linux(pcap_t *handle, struct bpf_program *filter)
881{
882#ifdef SO_ATTACH_FILTER
883 struct sock_fprog fcode;
884 int can_filter_in_kernel;
885 int err = 0;
886#endif
887
888 if (!handle)
889 return -1;
890 if (!filter) {
891 strncpy(handle->errbuf, "setfilter: No filter specified",
892 sizeof(handle->errbuf));
893 return -1;
894 }
895
896 /* Make our private copy of the filter */
897
898 if (install_bpf_program(handle, filter) < 0)
899 /* install_bpf_program() filled in errbuf */
900 return -1;
901
902 /*
903 * Run user level packet filter by default. Will be overriden if
904 * installing a kernel filter succeeds.
905 */
906 handle->md.use_bpf = 0;
907
908 /* Install kernel level filter if possible */
909
910#ifdef SO_ATTACH_FILTER
911#ifdef USHRT_MAX
912 if (handle->fcode.bf_len > USHRT_MAX) {
913 /*
914 * fcode.len is an unsigned short for current kernel.
915 * I have yet to see BPF-Code with that much
916 * instructions but still it is possible. So for the
917 * sake of correctness I added this check.
918 */
919 fprintf(stderr, "Warning: Filter too complex for kernel\n");
| 894 return 0;
895}
896
897/*
898 * Description string for the "any" device.
899 */
900static const char any_descr[] = "Pseudo-device that captures on all interfaces";
901
902int
903pcap_platform_finddevs(pcap_if_t **alldevsp, char *errbuf)
904{
905 if (pcap_add_if(alldevsp, "any", 0, any_descr, errbuf) < 0)
906 return (-1);
907
908#ifdef HAVE_DAG_API
909 if (dag_platform_finddevs(alldevsp, errbuf) < 0)
910 return (-1);
911#endif /* HAVE_DAG_API */
912
913#ifdef HAVE_SEPTEL_API
914 if (septel_platform_finddevs(alldevsp, errbuf) < 0)
915 return (-1);
916#endif /* HAVE_SEPTEL_API */
917
918 return (0);
919}
920
921/*
922 * Attach the given BPF code to the packet capture device.
923 */
924static int
925pcap_setfilter_linux(pcap_t *handle, struct bpf_program *filter)
926{
927#ifdef SO_ATTACH_FILTER
928 struct sock_fprog fcode;
929 int can_filter_in_kernel;
930 int err = 0;
931#endif
932
933 if (!handle)
934 return -1;
935 if (!filter) {
936 strncpy(handle->errbuf, "setfilter: No filter specified",
937 sizeof(handle->errbuf));
938 return -1;
939 }
940
941 /* Make our private copy of the filter */
942
943 if (install_bpf_program(handle, filter) < 0)
944 /* install_bpf_program() filled in errbuf */
945 return -1;
946
947 /*
948 * Run user level packet filter by default. Will be overriden if
949 * installing a kernel filter succeeds.
950 */
951 handle->md.use_bpf = 0;
952
953 /* Install kernel level filter if possible */
954
955#ifdef SO_ATTACH_FILTER
956#ifdef USHRT_MAX
957 if (handle->fcode.bf_len > USHRT_MAX) {
958 /*
959 * fcode.len is an unsigned short for current kernel.
960 * I have yet to see BPF-Code with that much
961 * instructions but still it is possible. So for the
962 * sake of correctness I added this check.
963 */
964 fprintf(stderr, "Warning: Filter too complex for kernel\n");
|
| 965 fcode.len = 0;
|
920 fcode.filter = NULL;
921 can_filter_in_kernel = 0;
922 } else
923#endif /* USHRT_MAX */
924 {
925 /*
926 * Oh joy, the Linux kernel uses struct sock_fprog instead
927 * of struct bpf_program and of course the length field is
928 * of different size. Pointed out by Sebastian
929 *
930 * Oh, and we also need to fix it up so that all "ret"
931 * instructions with non-zero operands have 65535 as the
932 * operand, and so that, if we're in cooked mode, all
933 * memory-reference instructions use special magic offsets
934 * in references to the link-layer header and assume that
935 * the link-layer payload begins at 0; "fix_program()"
936 * will do that.
937 */
938 switch (fix_program(handle, &fcode)) {
939
940 case -1:
941 default:
942 /*
943 * Fatal error; just quit.
944 * (The "default" case shouldn't happen; we
945 * return -1 for that reason.)
946 */
947 return -1;
948
949 case 0:
950 /*
951 * The program performed checks that we can't make
952 * work in the kernel.
953 */
954 can_filter_in_kernel = 0;
955 break;
956
957 case 1:
958 /*
959 * We have a filter that'll work in the kernel.
960 */
961 can_filter_in_kernel = 1;
962 break;
963 }
964 }
965
966 if (can_filter_in_kernel) {
967 if ((err = set_kernel_filter(handle, &fcode)) == 0)
968 {
969 /* Installation succeded - using kernel filter. */
970 handle->md.use_bpf = 1;
971 }
972 else if (err == -1) /* Non-fatal error */
973 {
974 /*
975 * Print a warning if we weren't able to install
976 * the filter for a reason other than "this kernel
977 * isn't configured to support socket filters.
978 */
979 if (errno != ENOPROTOOPT && errno != EOPNOTSUPP) {
980 fprintf(stderr,
981 "Warning: Kernel filter failed: %s\n",
982 pcap_strerror(errno));
983 }
984 }
985 }
986
987 /*
988 * If we're not using the kernel filter, get rid of any kernel
989 * filter that might've been there before, e.g. because the
990 * previous filter could work in the kernel, or because some other
991 * code attached a filter to the socket by some means other than
992 * calling "pcap_setfilter()". Otherwise, the kernel filter may
993 * filter out packets that would pass the new userland filter.
994 */
995 if (!handle->md.use_bpf)
996 reset_kernel_filter(handle);
997
998 /*
999 * Free up the copy of the filter that was made by "fix_program()".
1000 */
1001 if (fcode.filter != NULL)
1002 free(fcode.filter);
1003
1004 if (err == -2)
1005 /* Fatal error */
1006 return -1;
1007#endif /* SO_ATTACH_FILTER */
1008
1009 return 0;
1010}
1011
1012/*
1013 * Set direction flag: Which packets do we accept on a forwarding
1014 * single device? IN, OUT or both?
1015 */
1016static int
1017pcap_setdirection_linux(pcap_t *handle, pcap_direction_t d)
1018{
1019#ifdef HAVE_PF_PACKET_SOCKETS
1020 if (!handle->md.sock_packet) {
1021 handle->direction = d;
1022 return 0;
1023 }
1024#endif
1025 /*
1026 * We're not using PF_PACKET sockets, so we can't determine
1027 * the direction of the packet.
1028 */
1029 snprintf(handle->errbuf, sizeof(handle->errbuf),
1030 "Setting direction is not supported on SOCK_PACKET sockets");
1031 return -1;
1032}
1033
1034/*
1035 * Linux uses the ARP hardware type to identify the type of an
1036 * interface. pcap uses the DLT_xxx constants for this. This
1037 * function takes a pointer to a "pcap_t", and an ARPHRD_xxx
1038 * constant, as arguments, and sets "handle->linktype" to the
1039 * appropriate DLT_XXX constant and sets "handle->offset" to
1040 * the appropriate value (to make "handle->offset" plus link-layer
1041 * header length be a multiple of 4, so that the link-layer payload
1042 * will be aligned on a 4-byte boundary when capturing packets).
1043 * (If the offset isn't set here, it'll be 0; add code as appropriate
1044 * for cases where it shouldn't be 0.)
1045 *
1046 * If "cooked_ok" is non-zero, we can use DLT_LINUX_SLL and capture
1047 * in cooked mode; otherwise, we can't use cooked mode, so we have
1048 * to pick some type that works in raw mode, or fail.
1049 *
1050 * Sets the link type to -1 if unable to map the type.
1051 */
1052static void map_arphrd_to_dlt(pcap_t *handle, int arptype, int cooked_ok)
1053{
1054 switch (arptype) {
1055
1056 case ARPHRD_ETHER:
1057 /*
1058 * This is (presumably) a real Ethernet capture; give it a
1059 * link-layer-type list with DLT_EN10MB and DLT_DOCSIS, so
1060 * that an application can let you choose it, in case you're
1061 * capturing DOCSIS traffic that a Cisco Cable Modem
1062 * Termination System is putting out onto an Ethernet (it
1063 * doesn't put an Ethernet header onto the wire, it puts raw
1064 * DOCSIS frames out on the wire inside the low-level
1065 * Ethernet framing).
1066 *
1067 * XXX - are there any sorts of "fake Ethernet" that have
1068 * ARPHRD_ETHER but that *shouldn't offer DLT_DOCSIS as
1069 * a Cisco CMTS won't put traffic onto it or get traffic
1070 * bridged onto it? ISDN is handled in "live_open_new()",
1071 * as we fall back on cooked mode there; are there any
1072 * others?
1073 */
1074 handle->dlt_list = (u_int *) malloc(sizeof(u_int) * 2);
1075 /*
1076 * If that fails, just leave the list empty.
1077 */
1078 if (handle->dlt_list != NULL) {
1079 handle->dlt_list[0] = DLT_EN10MB;
1080 handle->dlt_list[1] = DLT_DOCSIS;
1081 handle->dlt_count = 2;
1082 }
1083 /* FALLTHROUGH */
1084
1085 case ARPHRD_METRICOM:
1086 case ARPHRD_LOOPBACK:
1087 handle->linktype = DLT_EN10MB;
1088 handle->offset = 2;
1089 break;
1090
1091 case ARPHRD_EETHER:
1092 handle->linktype = DLT_EN3MB;
1093 break;
1094
1095 case ARPHRD_AX25:
1096 handle->linktype = DLT_AX25;
1097 break;
1098
1099 case ARPHRD_PRONET:
1100 handle->linktype = DLT_PRONET;
1101 break;
1102
1103 case ARPHRD_CHAOS:
1104 handle->linktype = DLT_CHAOS;
1105 break;
1106
1107#ifndef ARPHRD_IEEE802_TR
1108#define ARPHRD_IEEE802_TR 800 /* From Linux 2.4 */
1109#endif
1110 case ARPHRD_IEEE802_TR:
1111 case ARPHRD_IEEE802:
1112 handle->linktype = DLT_IEEE802;
1113 handle->offset = 2;
1114 break;
1115
1116 case ARPHRD_ARCNET:
1117 handle->linktype = DLT_ARCNET_LINUX;
1118 break;
1119
1120#ifndef ARPHRD_FDDI /* From Linux 2.2.13 */
1121#define ARPHRD_FDDI 774
1122#endif
1123 case ARPHRD_FDDI:
1124 handle->linktype = DLT_FDDI;
1125 handle->offset = 3;
1126 break;
1127
1128#ifndef ARPHRD_ATM /* FIXME: How to #include this? */
1129#define ARPHRD_ATM 19
1130#endif
1131 case ARPHRD_ATM:
1132 /*
1133 * The Classical IP implementation in ATM for Linux
1134 * supports both what RFC 1483 calls "LLC Encapsulation",
1135 * in which each packet has an LLC header, possibly
1136 * with a SNAP header as well, prepended to it, and
1137 * what RFC 1483 calls "VC Based Multiplexing", in which
1138 * different virtual circuits carry different network
1139 * layer protocols, and no header is prepended to packets.
1140 *
1141 * They both have an ARPHRD_ type of ARPHRD_ATM, so
1142 * you can't use the ARPHRD_ type to find out whether
1143 * captured packets will have an LLC header, and,
1144 * while there's a socket ioctl to *set* the encapsulation
1145 * type, there's no ioctl to *get* the encapsulation type.
1146 *
1147 * This means that
1148 *
1149 * programs that dissect Linux Classical IP frames
1150 * would have to check for an LLC header and,
1151 * depending on whether they see one or not, dissect
1152 * the frame as LLC-encapsulated or as raw IP (I
1153 * don't know whether there's any traffic other than
1154 * IP that would show up on the socket, or whether
1155 * there's any support for IPv6 in the Linux
1156 * Classical IP code);
1157 *
1158 * filter expressions would have to compile into
1159 * code that checks for an LLC header and does
1160 * the right thing.
1161 *
1162 * Both of those are a nuisance - and, at least on systems
1163 * that support PF_PACKET sockets, we don't have to put
1164 * up with those nuisances; instead, we can just capture
1165 * in cooked mode. That's what we'll do, if we can.
1166 * Otherwise, we'll just fail.
1167 */
1168 if (cooked_ok)
1169 handle->linktype = DLT_LINUX_SLL;
1170 else
1171 handle->linktype = -1;
1172 break;
1173
1174#ifndef ARPHRD_IEEE80211 /* From Linux 2.4.6 */
1175#define ARPHRD_IEEE80211 801
1176#endif
1177 case ARPHRD_IEEE80211:
1178 handle->linktype = DLT_IEEE802_11;
1179 break;
1180
1181#ifndef ARPHRD_IEEE80211_PRISM /* From Linux 2.4.18 */
1182#define ARPHRD_IEEE80211_PRISM 802
1183#endif
1184 case ARPHRD_IEEE80211_PRISM:
1185 handle->linktype = DLT_PRISM_HEADER;
1186 break;
1187
1188#ifndef ARPHRD_IEEE80211_RADIOTAP /* new */
1189#define ARPHRD_IEEE80211_RADIOTAP 803
1190#endif
1191 case ARPHRD_IEEE80211_RADIOTAP:
1192 handle->linktype = DLT_IEEE802_11_RADIO;
1193 break;
1194
1195 case ARPHRD_PPP:
1196 /*
1197 * Some PPP code in the kernel supplies no link-layer
1198 * header whatsoever to PF_PACKET sockets; other PPP
1199 * code supplies PPP link-layer headers ("syncppp.c");
1200 * some PPP code might supply random link-layer
1201 * headers (PPP over ISDN - there's code in Ethereal,
1202 * for example, to cope with PPP-over-ISDN captures
1203 * with which the Ethereal developers have had to cope,
1204 * heuristically trying to determine which of the
1205 * oddball link-layer headers particular packets have).
1206 *
1207 * As such, we just punt, and run all PPP interfaces
1208 * in cooked mode, if we can; otherwise, we just treat
1209 * it as DLT_RAW, for now - if somebody needs to capture,
1210 * on a 2.0[.x] kernel, on PPP devices that supply a
1211 * link-layer header, they'll have to add code here to
1212 * map to the appropriate DLT_ type (possibly adding a
1213 * new DLT_ type, if necessary).
1214 */
1215 if (cooked_ok)
1216 handle->linktype = DLT_LINUX_SLL;
1217 else {
1218 /*
1219 * XXX - handle ISDN types here? We can't fall
1220 * back on cooked sockets, so we'd have to
1221 * figure out from the device name what type of
1222 * link-layer encapsulation it's using, and map
1223 * that to an appropriate DLT_ value, meaning
1224 * we'd map "isdnN" devices to DLT_RAW (they
1225 * supply raw IP packets with no link-layer
1226 * header) and "isdY" devices to a new DLT_I4L_IP
1227 * type that has only an Ethernet packet type as
1228 * a link-layer header.
1229 *
1230 * But sometimes we seem to get random crap
1231 * in the link-layer header when capturing on
1232 * ISDN devices....
1233 */
1234 handle->linktype = DLT_RAW;
1235 }
1236 break;
1237
1238#ifndef ARPHRD_CISCO
1239#define ARPHRD_CISCO 513 /* previously ARPHRD_HDLC */
1240#endif
1241 case ARPHRD_CISCO:
1242 handle->linktype = DLT_C_HDLC;
1243 break;
1244
1245 /* Not sure if this is correct for all tunnels, but it
1246 * works for CIPE */
1247 case ARPHRD_TUNNEL:
1248#ifndef ARPHRD_SIT
1249#define ARPHRD_SIT 776 /* From Linux 2.2.13 */
1250#endif
1251 case ARPHRD_SIT:
1252 case ARPHRD_CSLIP:
1253 case ARPHRD_SLIP6:
1254 case ARPHRD_CSLIP6:
1255 case ARPHRD_ADAPT:
1256 case ARPHRD_SLIP:
1257#ifndef ARPHRD_RAWHDLC
1258#define ARPHRD_RAWHDLC 518
1259#endif
1260 case ARPHRD_RAWHDLC:
1261#ifndef ARPHRD_DLCI
1262#define ARPHRD_DLCI 15
1263#endif
1264 case ARPHRD_DLCI:
1265 /*
1266 * XXX - should some of those be mapped to DLT_LINUX_SLL
1267 * instead? Should we just map all of them to DLT_LINUX_SLL?
1268 */
1269 handle->linktype = DLT_RAW;
1270 break;
1271
1272#ifndef ARPHRD_FRAD
1273#define ARPHRD_FRAD 770
1274#endif
1275 case ARPHRD_FRAD:
1276 handle->linktype = DLT_FRELAY;
1277 break;
1278
1279 case ARPHRD_LOCALTLK:
1280 handle->linktype = DLT_LTALK;
1281 break;
1282
1283#ifndef ARPHRD_FCPP
1284#define ARPHRD_FCPP 784
1285#endif
1286 case ARPHRD_FCPP:
1287#ifndef ARPHRD_FCAL
1288#define ARPHRD_FCAL 785
1289#endif
1290 case ARPHRD_FCAL:
1291#ifndef ARPHRD_FCPL
1292#define ARPHRD_FCPL 786
1293#endif
1294 case ARPHRD_FCPL:
1295#ifndef ARPHRD_FCFABRIC
1296#define ARPHRD_FCFABRIC 787
1297#endif
1298 case ARPHRD_FCFABRIC:
1299 /*
1300 * We assume that those all mean RFC 2625 IP-over-
1301 * Fibre Channel, with the RFC 2625 header at
1302 * the beginning of the packet.
1303 */
1304 handle->linktype = DLT_IP_OVER_FC;
1305 break;
1306
1307#ifndef ARPHRD_IRDA
1308#define ARPHRD_IRDA 783
1309#endif
1310 case ARPHRD_IRDA:
1311 /* Don't expect IP packet out of this interfaces... */
1312 handle->linktype = DLT_LINUX_IRDA;
1313 /* We need to save packet direction for IrDA decoding,
1314 * so let's use "Linux-cooked" mode. Jean II */
1315 //handle->md.cooked = 1;
1316 break;
1317
| 966 fcode.filter = NULL;
967 can_filter_in_kernel = 0;
968 } else
969#endif /* USHRT_MAX */
970 {
971 /*
972 * Oh joy, the Linux kernel uses struct sock_fprog instead
973 * of struct bpf_program and of course the length field is
974 * of different size. Pointed out by Sebastian
975 *
976 * Oh, and we also need to fix it up so that all "ret"
977 * instructions with non-zero operands have 65535 as the
978 * operand, and so that, if we're in cooked mode, all
979 * memory-reference instructions use special magic offsets
980 * in references to the link-layer header and assume that
981 * the link-layer payload begins at 0; "fix_program()"
982 * will do that.
983 */
984 switch (fix_program(handle, &fcode)) {
985
986 case -1:
987 default:
988 /*
989 * Fatal error; just quit.
990 * (The "default" case shouldn't happen; we
991 * return -1 for that reason.)
992 */
993 return -1;
994
995 case 0:
996 /*
997 * The program performed checks that we can't make
998 * work in the kernel.
999 */
1000 can_filter_in_kernel = 0;
1001 break;
1002
1003 case 1:
1004 /*
1005 * We have a filter that'll work in the kernel.
1006 */
1007 can_filter_in_kernel = 1;
1008 break;
1009 }
1010 }
1011
1012 if (can_filter_in_kernel) {
1013 if ((err = set_kernel_filter(handle, &fcode)) == 0)
1014 {
1015 /* Installation succeded - using kernel filter. */
1016 handle->md.use_bpf = 1;
1017 }
1018 else if (err == -1) /* Non-fatal error */
1019 {
1020 /*
1021 * Print a warning if we weren't able to install
1022 * the filter for a reason other than "this kernel
1023 * isn't configured to support socket filters.
1024 */
1025 if (errno != ENOPROTOOPT && errno != EOPNOTSUPP) {
1026 fprintf(stderr,
1027 "Warning: Kernel filter failed: %s\n",
1028 pcap_strerror(errno));
1029 }
1030 }
1031 }
1032
1033 /*
1034 * If we're not using the kernel filter, get rid of any kernel
1035 * filter that might've been there before, e.g. because the
1036 * previous filter could work in the kernel, or because some other
1037 * code attached a filter to the socket by some means other than
1038 * calling "pcap_setfilter()". Otherwise, the kernel filter may
1039 * filter out packets that would pass the new userland filter.
1040 */
1041 if (!handle->md.use_bpf)
1042 reset_kernel_filter(handle);
1043
1044 /*
1045 * Free up the copy of the filter that was made by "fix_program()".
1046 */
1047 if (fcode.filter != NULL)
1048 free(fcode.filter);
1049
1050 if (err == -2)
1051 /* Fatal error */
1052 return -1;
1053#endif /* SO_ATTACH_FILTER */
1054
1055 return 0;
1056}
1057
1058/*
1059 * Set direction flag: Which packets do we accept on a forwarding
1060 * single device? IN, OUT or both?
1061 */
1062static int
1063pcap_setdirection_linux(pcap_t *handle, pcap_direction_t d)
1064{
1065#ifdef HAVE_PF_PACKET_SOCKETS
1066 if (!handle->md.sock_packet) {
1067 handle->direction = d;
1068 return 0;
1069 }
1070#endif
1071 /*
1072 * We're not using PF_PACKET sockets, so we can't determine
1073 * the direction of the packet.
1074 */
1075 snprintf(handle->errbuf, sizeof(handle->errbuf),
1076 "Setting direction is not supported on SOCK_PACKET sockets");
1077 return -1;
1078}
1079
1080/*
1081 * Linux uses the ARP hardware type to identify the type of an
1082 * interface. pcap uses the DLT_xxx constants for this. This
1083 * function takes a pointer to a "pcap_t", and an ARPHRD_xxx
1084 * constant, as arguments, and sets "handle->linktype" to the
1085 * appropriate DLT_XXX constant and sets "handle->offset" to
1086 * the appropriate value (to make "handle->offset" plus link-layer
1087 * header length be a multiple of 4, so that the link-layer payload
1088 * will be aligned on a 4-byte boundary when capturing packets).
1089 * (If the offset isn't set here, it'll be 0; add code as appropriate
1090 * for cases where it shouldn't be 0.)
1091 *
1092 * If "cooked_ok" is non-zero, we can use DLT_LINUX_SLL and capture
1093 * in cooked mode; otherwise, we can't use cooked mode, so we have
1094 * to pick some type that works in raw mode, or fail.
1095 *
1096 * Sets the link type to -1 if unable to map the type.
1097 */
1098static void map_arphrd_to_dlt(pcap_t *handle, int arptype, int cooked_ok)
1099{
1100 switch (arptype) {
1101
1102 case ARPHRD_ETHER:
1103 /*
1104 * This is (presumably) a real Ethernet capture; give it a
1105 * link-layer-type list with DLT_EN10MB and DLT_DOCSIS, so
1106 * that an application can let you choose it, in case you're
1107 * capturing DOCSIS traffic that a Cisco Cable Modem
1108 * Termination System is putting out onto an Ethernet (it
1109 * doesn't put an Ethernet header onto the wire, it puts raw
1110 * DOCSIS frames out on the wire inside the low-level
1111 * Ethernet framing).
1112 *
1113 * XXX - are there any sorts of "fake Ethernet" that have
1114 * ARPHRD_ETHER but that *shouldn't offer DLT_DOCSIS as
1115 * a Cisco CMTS won't put traffic onto it or get traffic
1116 * bridged onto it? ISDN is handled in "live_open_new()",
1117 * as we fall back on cooked mode there; are there any
1118 * others?
1119 */
1120 handle->dlt_list = (u_int *) malloc(sizeof(u_int) * 2);
1121 /*
1122 * If that fails, just leave the list empty.
1123 */
1124 if (handle->dlt_list != NULL) {
1125 handle->dlt_list[0] = DLT_EN10MB;
1126 handle->dlt_list[1] = DLT_DOCSIS;
1127 handle->dlt_count = 2;
1128 }
1129 /* FALLTHROUGH */
1130
1131 case ARPHRD_METRICOM:
1132 case ARPHRD_LOOPBACK:
1133 handle->linktype = DLT_EN10MB;
1134 handle->offset = 2;
1135 break;
1136
1137 case ARPHRD_EETHER:
1138 handle->linktype = DLT_EN3MB;
1139 break;
1140
1141 case ARPHRD_AX25:
1142 handle->linktype = DLT_AX25;
1143 break;
1144
1145 case ARPHRD_PRONET:
1146 handle->linktype = DLT_PRONET;
1147 break;
1148
1149 case ARPHRD_CHAOS:
1150 handle->linktype = DLT_CHAOS;
1151 break;
1152
1153#ifndef ARPHRD_IEEE802_TR
1154#define ARPHRD_IEEE802_TR 800 /* From Linux 2.4 */
1155#endif
1156 case ARPHRD_IEEE802_TR:
1157 case ARPHRD_IEEE802:
1158 handle->linktype = DLT_IEEE802;
1159 handle->offset = 2;
1160 break;
1161
1162 case ARPHRD_ARCNET:
1163 handle->linktype = DLT_ARCNET_LINUX;
1164 break;
1165
1166#ifndef ARPHRD_FDDI /* From Linux 2.2.13 */
1167#define ARPHRD_FDDI 774
1168#endif
1169 case ARPHRD_FDDI:
1170 handle->linktype = DLT_FDDI;
1171 handle->offset = 3;
1172 break;
1173
1174#ifndef ARPHRD_ATM /* FIXME: How to #include this? */
1175#define ARPHRD_ATM 19
1176#endif
1177 case ARPHRD_ATM:
1178 /*
1179 * The Classical IP implementation in ATM for Linux
1180 * supports both what RFC 1483 calls "LLC Encapsulation",
1181 * in which each packet has an LLC header, possibly
1182 * with a SNAP header as well, prepended to it, and
1183 * what RFC 1483 calls "VC Based Multiplexing", in which
1184 * different virtual circuits carry different network
1185 * layer protocols, and no header is prepended to packets.
1186 *
1187 * They both have an ARPHRD_ type of ARPHRD_ATM, so
1188 * you can't use the ARPHRD_ type to find out whether
1189 * captured packets will have an LLC header, and,
1190 * while there's a socket ioctl to *set* the encapsulation
1191 * type, there's no ioctl to *get* the encapsulation type.
1192 *
1193 * This means that
1194 *
1195 * programs that dissect Linux Classical IP frames
1196 * would have to check for an LLC header and,
1197 * depending on whether they see one or not, dissect
1198 * the frame as LLC-encapsulated or as raw IP (I
1199 * don't know whether there's any traffic other than
1200 * IP that would show up on the socket, or whether
1201 * there's any support for IPv6 in the Linux
1202 * Classical IP code);
1203 *
1204 * filter expressions would have to compile into
1205 * code that checks for an LLC header and does
1206 * the right thing.
1207 *
1208 * Both of those are a nuisance - and, at least on systems
1209 * that support PF_PACKET sockets, we don't have to put
1210 * up with those nuisances; instead, we can just capture
1211 * in cooked mode. That's what we'll do, if we can.
1212 * Otherwise, we'll just fail.
1213 */
1214 if (cooked_ok)
1215 handle->linktype = DLT_LINUX_SLL;
1216 else
1217 handle->linktype = -1;
1218 break;
1219
1220#ifndef ARPHRD_IEEE80211 /* From Linux 2.4.6 */
1221#define ARPHRD_IEEE80211 801
1222#endif
1223 case ARPHRD_IEEE80211:
1224 handle->linktype = DLT_IEEE802_11;
1225 break;
1226
1227#ifndef ARPHRD_IEEE80211_PRISM /* From Linux 2.4.18 */
1228#define ARPHRD_IEEE80211_PRISM 802
1229#endif
1230 case ARPHRD_IEEE80211_PRISM:
1231 handle->linktype = DLT_PRISM_HEADER;
1232 break;
1233
1234#ifndef ARPHRD_IEEE80211_RADIOTAP /* new */
1235#define ARPHRD_IEEE80211_RADIOTAP 803
1236#endif
1237 case ARPHRD_IEEE80211_RADIOTAP:
1238 handle->linktype = DLT_IEEE802_11_RADIO;
1239 break;
1240
1241 case ARPHRD_PPP:
1242 /*
1243 * Some PPP code in the kernel supplies no link-layer
1244 * header whatsoever to PF_PACKET sockets; other PPP
1245 * code supplies PPP link-layer headers ("syncppp.c");
1246 * some PPP code might supply random link-layer
1247 * headers (PPP over ISDN - there's code in Ethereal,
1248 * for example, to cope with PPP-over-ISDN captures
1249 * with which the Ethereal developers have had to cope,
1250 * heuristically trying to determine which of the
1251 * oddball link-layer headers particular packets have).
1252 *
1253 * As such, we just punt, and run all PPP interfaces
1254 * in cooked mode, if we can; otherwise, we just treat
1255 * it as DLT_RAW, for now - if somebody needs to capture,
1256 * on a 2.0[.x] kernel, on PPP devices that supply a
1257 * link-layer header, they'll have to add code here to
1258 * map to the appropriate DLT_ type (possibly adding a
1259 * new DLT_ type, if necessary).
1260 */
1261 if (cooked_ok)
1262 handle->linktype = DLT_LINUX_SLL;
1263 else {
1264 /*
1265 * XXX - handle ISDN types here? We can't fall
1266 * back on cooked sockets, so we'd have to
1267 * figure out from the device name what type of
1268 * link-layer encapsulation it's using, and map
1269 * that to an appropriate DLT_ value, meaning
1270 * we'd map "isdnN" devices to DLT_RAW (they
1271 * supply raw IP packets with no link-layer
1272 * header) and "isdY" devices to a new DLT_I4L_IP
1273 * type that has only an Ethernet packet type as
1274 * a link-layer header.
1275 *
1276 * But sometimes we seem to get random crap
1277 * in the link-layer header when capturing on
1278 * ISDN devices....
1279 */
1280 handle->linktype = DLT_RAW;
1281 }
1282 break;
1283
1284#ifndef ARPHRD_CISCO
1285#define ARPHRD_CISCO 513 /* previously ARPHRD_HDLC */
1286#endif
1287 case ARPHRD_CISCO:
1288 handle->linktype = DLT_C_HDLC;
1289 break;
1290
1291 /* Not sure if this is correct for all tunnels, but it
1292 * works for CIPE */
1293 case ARPHRD_TUNNEL:
1294#ifndef ARPHRD_SIT
1295#define ARPHRD_SIT 776 /* From Linux 2.2.13 */
1296#endif
1297 case ARPHRD_SIT:
1298 case ARPHRD_CSLIP:
1299 case ARPHRD_SLIP6:
1300 case ARPHRD_CSLIP6:
1301 case ARPHRD_ADAPT:
1302 case ARPHRD_SLIP:
1303#ifndef ARPHRD_RAWHDLC
1304#define ARPHRD_RAWHDLC 518
1305#endif
1306 case ARPHRD_RAWHDLC:
1307#ifndef ARPHRD_DLCI
1308#define ARPHRD_DLCI 15
1309#endif
1310 case ARPHRD_DLCI:
1311 /*
1312 * XXX - should some of those be mapped to DLT_LINUX_SLL
1313 * instead? Should we just map all of them to DLT_LINUX_SLL?
1314 */
1315 handle->linktype = DLT_RAW;
1316 break;
1317
1318#ifndef ARPHRD_FRAD
1319#define ARPHRD_FRAD 770
1320#endif
1321 case ARPHRD_FRAD:
1322 handle->linktype = DLT_FRELAY;
1323 break;
1324
1325 case ARPHRD_LOCALTLK:
1326 handle->linktype = DLT_LTALK;
1327 break;
1328
1329#ifndef ARPHRD_FCPP
1330#define ARPHRD_FCPP 784
1331#endif
1332 case ARPHRD_FCPP:
1333#ifndef ARPHRD_FCAL
1334#define ARPHRD_FCAL 785
1335#endif
1336 case ARPHRD_FCAL:
1337#ifndef ARPHRD_FCPL
1338#define ARPHRD_FCPL 786
1339#endif
1340 case ARPHRD_FCPL:
1341#ifndef ARPHRD_FCFABRIC
1342#define ARPHRD_FCFABRIC 787
1343#endif
1344 case ARPHRD_FCFABRIC:
1345 /*
1346 * We assume that those all mean RFC 2625 IP-over-
1347 * Fibre Channel, with the RFC 2625 header at
1348 * the beginning of the packet.
1349 */
1350 handle->linktype = DLT_IP_OVER_FC;
1351 break;
1352
1353#ifndef ARPHRD_IRDA
1354#define ARPHRD_IRDA 783
1355#endif
1356 case ARPHRD_IRDA:
1357 /* Don't expect IP packet out of this interfaces... */
1358 handle->linktype = DLT_LINUX_IRDA;
1359 /* We need to save packet direction for IrDA decoding,
1360 * so let's use "Linux-cooked" mode. Jean II */
1361 //handle->md.cooked = 1;
1362 break;
1363
|
| 1364 /* ARPHRD_LAPD is unofficial and randomly allocated, if reallocation
1365 * is needed, please report it to <daniele@orlandi.com> */
1366#ifndef ARPHRD_LAPD
1367#define ARPHRD_LAPD 8445
1368#endif
1369 case ARPHRD_LAPD:
1370 /* Don't expect IP packet out of this interfaces... */
1371 handle->linktype = DLT_LINUX_LAPD;
1372 break;
1373
|
1318 default:
1319 handle->linktype = -1;
1320 break;
1321 }
1322}
1323
1324/* ===== Functions to interface to the newer kernels ================== */
1325
1326/*
1327 * Try to open a packet socket using the new kernel interface.
1328 * Returns 0 on failure.
1329 * FIXME: 0 uses to mean success (Sebastian)
1330 */
1331static int
1332live_open_new(pcap_t *handle, const char *device, int promisc,
1333 int to_ms, char *ebuf)
1334{
1335#ifdef HAVE_PF_PACKET_SOCKETS
1336 int sock_fd = -1, arptype;
1337 int err;
1338 int fatal_err = 0;
1339 struct packet_mreq mr;
1340
1341 /* One shot loop used for error handling - bail out with break */
1342
1343 do {
1344 /*
1345 * Open a socket with protocol family packet. If a device is
1346 * given we try to open it in raw mode otherwise we use
1347 * the cooked interface.
1348 */
1349 sock_fd = device ?
1350 socket(PF_PACKET, SOCK_RAW, htons(ETH_P_ALL))
1351 : socket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_ALL));
1352
1353 if (sock_fd == -1) {
1354 snprintf(ebuf, PCAP_ERRBUF_SIZE, "socket: %s",
1355 pcap_strerror(errno) );
1356 break;
1357 }
1358
1359 /* It seems the kernel supports the new interface. */
1360 handle->md.sock_packet = 0;
1361
1362 /*
1363 * Get the interface index of the loopback device.
1364 * If the attempt fails, don't fail, just set the
1365 * "md.lo_ifindex" to -1.
1366 *
1367 * XXX - can there be more than one device that loops
1368 * packets back, i.e. devices other than "lo"? If so,
1369 * we'd need to find them all, and have an array of
1370 * indices for them, and check all of them in
1371 * "pcap_read_packet()".
1372 */
1373 handle->md.lo_ifindex = iface_get_id(sock_fd, "lo", ebuf);
1374
1375 /*
1376 * Default value for offset to align link-layer payload
1377 * on a 4-byte boundary.
1378 */
1379 handle->offset = 0;
1380
1381 /*
1382 * What kind of frames do we have to deal with? Fall back
1383 * to cooked mode if we have an unknown interface type.
1384 */
1385
1386 if (device) {
1387 /* Assume for now we don't need cooked mode. */
1388 handle->md.cooked = 0;
1389
1390 arptype = iface_get_arptype(sock_fd, device, ebuf);
1391 if (arptype == -1) {
1392 fatal_err = 1;
1393 break;
1394 }
1395 map_arphrd_to_dlt(handle, arptype, 1);
1396 if (handle->linktype == -1 ||
1397 handle->linktype == DLT_LINUX_SLL ||
1398 handle->linktype == DLT_LINUX_IRDA ||
| 1374 default:
1375 handle->linktype = -1;
1376 break;
1377 }
1378}
1379
1380/* ===== Functions to interface to the newer kernels ================== */
1381
1382/*
1383 * Try to open a packet socket using the new kernel interface.
1384 * Returns 0 on failure.
1385 * FIXME: 0 uses to mean success (Sebastian)
1386 */
1387static int
1388live_open_new(pcap_t *handle, const char *device, int promisc,
1389 int to_ms, char *ebuf)
1390{
1391#ifdef HAVE_PF_PACKET_SOCKETS
1392 int sock_fd = -1, arptype;
1393 int err;
1394 int fatal_err = 0;
1395 struct packet_mreq mr;
1396
1397 /* One shot loop used for error handling - bail out with break */
1398
1399 do {
1400 /*
1401 * Open a socket with protocol family packet. If a device is
1402 * given we try to open it in raw mode otherwise we use
1403 * the cooked interface.
1404 */
1405 sock_fd = device ?
1406 socket(PF_PACKET, SOCK_RAW, htons(ETH_P_ALL))
1407 : socket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_ALL));
1408
1409 if (sock_fd == -1) {
1410 snprintf(ebuf, PCAP_ERRBUF_SIZE, "socket: %s",
1411 pcap_strerror(errno) );
1412 break;
1413 }
1414
1415 /* It seems the kernel supports the new interface. */
1416 handle->md.sock_packet = 0;
1417
1418 /*
1419 * Get the interface index of the loopback device.
1420 * If the attempt fails, don't fail, just set the
1421 * "md.lo_ifindex" to -1.
1422 *
1423 * XXX - can there be more than one device that loops
1424 * packets back, i.e. devices other than "lo"? If so,
1425 * we'd need to find them all, and have an array of
1426 * indices for them, and check all of them in
1427 * "pcap_read_packet()".
1428 */
1429 handle->md.lo_ifindex = iface_get_id(sock_fd, "lo", ebuf);
1430
1431 /*
1432 * Default value for offset to align link-layer payload
1433 * on a 4-byte boundary.
1434 */
1435 handle->offset = 0;
1436
1437 /*
1438 * What kind of frames do we have to deal with? Fall back
1439 * to cooked mode if we have an unknown interface type.
1440 */
1441
1442 if (device) {
1443 /* Assume for now we don't need cooked mode. */
1444 handle->md.cooked = 0;
1445
1446 arptype = iface_get_arptype(sock_fd, device, ebuf);
1447 if (arptype == -1) {
1448 fatal_err = 1;
1449 break;
1450 }
1451 map_arphrd_to_dlt(handle, arptype, 1);
1452 if (handle->linktype == -1 ||
1453 handle->linktype == DLT_LINUX_SLL ||
1454 handle->linktype == DLT_LINUX_IRDA ||
|
| 1455 handle->linktype == DLT_LINUX_LAPD ||
|
1399 (handle->linktype == DLT_EN10MB &&
1400 (strncmp("isdn", device, 4) == 0 ||
1401 strncmp("isdY", device, 4) == 0))) {
1402 /*
1403 * Unknown interface type (-1), or a
1404 * device we explicitly chose to run
1405 * in cooked mode (e.g., PPP devices),
1406 * or an ISDN device (whose link-layer
1407 * type we can only determine by using
1408 * APIs that may be different on different
1409 * kernels) - reopen in cooked mode.
1410 */
1411 if (close(sock_fd) == -1) {
1412 snprintf(ebuf, PCAP_ERRBUF_SIZE,
1413 "close: %s", pcap_strerror(errno));
1414 break;
1415 }
1416 sock_fd = socket(PF_PACKET, SOCK_DGRAM,
1417 htons(ETH_P_ALL));
1418 if (sock_fd == -1) {
1419 snprintf(ebuf, PCAP_ERRBUF_SIZE,
1420 "socket: %s", pcap_strerror(errno));
1421 break;
1422 }
1423 handle->md.cooked = 1;
1424
1425 /*
1426 * Get rid of any link-layer type list
1427 * we allocated - this only supports cooked
1428 * capture.
1429 */
1430 if (handle->dlt_list != NULL) {
1431 free(handle->dlt_list);
1432 handle->dlt_list = NULL;
1433 handle->dlt_count = 0;
1434 }
1435
1436 if (handle->linktype == -1) {
1437 /*
1438 * Warn that we're falling back on
1439 * cooked mode; we may want to
1440 * update "map_arphrd_to_dlt()"
1441 * to handle the new type.
1442 */
1443 snprintf(ebuf, PCAP_ERRBUF_SIZE,
1444 "arptype %d not "
1445 "supported by libpcap - "
1446 "falling back to cooked "
1447 "socket",
1448 arptype);
1449 }
1450 /* IrDA capture is not a real "cooked" capture,
1451 * it's IrLAP frames, not IP packets. */
| 1456 (handle->linktype == DLT_EN10MB &&
1457 (strncmp("isdn", device, 4) == 0 ||
1458 strncmp("isdY", device, 4) == 0))) {
1459 /*
1460 * Unknown interface type (-1), or a
1461 * device we explicitly chose to run
1462 * in cooked mode (e.g., PPP devices),
1463 * or an ISDN device (whose link-layer
1464 * type we can only determine by using
1465 * APIs that may be different on different
1466 * kernels) - reopen in cooked mode.
1467 */
1468 if (close(sock_fd) == -1) {
1469 snprintf(ebuf, PCAP_ERRBUF_SIZE,
1470 "close: %s", pcap_strerror(errno));
1471 break;
1472 }
1473 sock_fd = socket(PF_PACKET, SOCK_DGRAM,
1474 htons(ETH_P_ALL));
1475 if (sock_fd == -1) {
1476 snprintf(ebuf, PCAP_ERRBUF_SIZE,
1477 "socket: %s", pcap_strerror(errno));
1478 break;
1479 }
1480 handle->md.cooked = 1;
1481
1482 /*
1483 * Get rid of any link-layer type list
1484 * we allocated - this only supports cooked
1485 * capture.
1486 */
1487 if (handle->dlt_list != NULL) {
1488 free(handle->dlt_list);
1489 handle->dlt_list = NULL;
1490 handle->dlt_count = 0;
1491 }
1492
1493 if (handle->linktype == -1) {
1494 /*
1495 * Warn that we're falling back on
1496 * cooked mode; we may want to
1497 * update "map_arphrd_to_dlt()"
1498 * to handle the new type.
1499 */
1500 snprintf(ebuf, PCAP_ERRBUF_SIZE,
1501 "arptype %d not "
1502 "supported by libpcap - "
1503 "falling back to cooked "
1504 "socket",
1505 arptype);
1506 }
1507 /* IrDA capture is not a real "cooked" capture,
1508 * it's IrLAP frames, not IP packets. */
|
1452 if (handle->linktype != DLT_LINUX_IRDA)
| 1509 if (handle->linktype != DLT_LINUX_IRDA &&
1510 handle->linktype != DLT_LINUX_LAPD)
|
1453 handle->linktype = DLT_LINUX_SLL;
1454 }
1455
1456 handle->md.ifindex = iface_get_id(sock_fd, device, ebuf);
1457 if (handle->md.ifindex == -1)
1458 break;
1459
1460 if ((err = iface_bind(sock_fd, handle->md.ifindex,
1461 ebuf)) < 0) {
1462 if (err == -2)
1463 fatal_err = 1;
1464 break;
1465 }
1466 } else {
1467 /*
1468 * This is cooked mode.
1469 */
1470 handle->md.cooked = 1;
1471 handle->linktype = DLT_LINUX_SLL;
1472
1473 /*
1474 * We're not bound to a device.
1475 * XXX - true? Or true only if we're using
1476 * the "any" device?
1477 * For now, we're using this as an indication
1478 * that we can't transmit; stop doing that only
1479 * if we figure out how to transmit in cooked
1480 * mode.
1481 */
1482 handle->md.ifindex = -1;
1483 }
1484
1485 /*
1486 * Select promiscuous mode on if "promisc" is set.
1487 *
1488 * Do not turn allmulti mode on if we don't select
1489 * promiscuous mode - on some devices (e.g., Orinoco
1490 * wireless interfaces), allmulti mode isn't supported
1491 * and the driver implements it by turning promiscuous
1492 * mode on, and that screws up the operation of the
1493 * card as a normal networking interface, and on no
1494 * other platform I know of does starting a non-
1495 * promiscuous capture affect which multicast packets
1496 * are received by the interface.
1497 */
1498
1499 /*
1500 * Hmm, how can we set promiscuous mode on all interfaces?
1501 * I am not sure if that is possible at all.
1502 */
1503
1504 if (device && promisc) {
1505 memset(&mr, 0, sizeof(mr));
1506 mr.mr_ifindex = handle->md.ifindex;
1507 mr.mr_type = PACKET_MR_PROMISC;
1508 if (setsockopt(sock_fd, SOL_PACKET,
1509 PACKET_ADD_MEMBERSHIP, &mr, sizeof(mr)) == -1)
1510 {
1511 snprintf(ebuf, PCAP_ERRBUF_SIZE,
1512 "setsockopt: %s", pcap_strerror(errno));
1513 break;
1514 }
1515 }
1516
1517 /* Save the socket FD in the pcap structure */
1518
1519 handle->fd = sock_fd;
1520
1521 return 1;
1522
1523 } while(0);
1524
1525 if (sock_fd != -1)
1526 close(sock_fd);
1527
1528 if (fatal_err) {
1529 /*
1530 * Get rid of any link-layer type list we allocated.
1531 */
1532 if (handle->dlt_list != NULL)
1533 free(handle->dlt_list);
1534 return -2;
1535 } else
1536 return 0;
1537#else
1538 strncpy(ebuf,
1539 "New packet capturing interface not supported by build "
1540 "environment", PCAP_ERRBUF_SIZE);
1541 return 0;
1542#endif
1543}
1544
1545#ifdef HAVE_PF_PACKET_SOCKETS
1546/*
1547 * Return the index of the given device name. Fill ebuf and return
1548 * -1 on failure.
1549 */
1550static int
1551iface_get_id(int fd, const char *device, char *ebuf)
1552{
1553 struct ifreq ifr;
1554
1555 memset(&ifr, 0, sizeof(ifr));
1556 strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name));
1557
1558 if (ioctl(fd, SIOCGIFINDEX, &ifr) == -1) {
1559 snprintf(ebuf, PCAP_ERRBUF_SIZE,
| 1511 handle->linktype = DLT_LINUX_SLL;
1512 }
1513
1514 handle->md.ifindex = iface_get_id(sock_fd, device, ebuf);
1515 if (handle->md.ifindex == -1)
1516 break;
1517
1518 if ((err = iface_bind(sock_fd, handle->md.ifindex,
1519 ebuf)) < 0) {
1520 if (err == -2)
1521 fatal_err = 1;
1522 break;
1523 }
1524 } else {
1525 /*
1526 * This is cooked mode.
1527 */
1528 handle->md.cooked = 1;
1529 handle->linktype = DLT_LINUX_SLL;
1530
1531 /*
1532 * We're not bound to a device.
1533 * XXX - true? Or true only if we're using
1534 * the "any" device?
1535 * For now, we're using this as an indication
1536 * that we can't transmit; stop doing that only
1537 * if we figure out how to transmit in cooked
1538 * mode.
1539 */
1540 handle->md.ifindex = -1;
1541 }
1542
1543 /*
1544 * Select promiscuous mode on if "promisc" is set.
1545 *
1546 * Do not turn allmulti mode on if we don't select
1547 * promiscuous mode - on some devices (e.g., Orinoco
1548 * wireless interfaces), allmulti mode isn't supported
1549 * and the driver implements it by turning promiscuous
1550 * mode on, and that screws up the operation of the
1551 * card as a normal networking interface, and on no
1552 * other platform I know of does starting a non-
1553 * promiscuous capture affect which multicast packets
1554 * are received by the interface.
1555 */
1556
1557 /*
1558 * Hmm, how can we set promiscuous mode on all interfaces?
1559 * I am not sure if that is possible at all.
1560 */
1561
1562 if (device && promisc) {
1563 memset(&mr, 0, sizeof(mr));
1564 mr.mr_ifindex = handle->md.ifindex;
1565 mr.mr_type = PACKET_MR_PROMISC;
1566 if (setsockopt(sock_fd, SOL_PACKET,
1567 PACKET_ADD_MEMBERSHIP, &mr, sizeof(mr)) == -1)
1568 {
1569 snprintf(ebuf, PCAP_ERRBUF_SIZE,
1570 "setsockopt: %s", pcap_strerror(errno));
1571 break;
1572 }
1573 }
1574
1575 /* Save the socket FD in the pcap structure */
1576
1577 handle->fd = sock_fd;
1578
1579 return 1;
1580
1581 } while(0);
1582
1583 if (sock_fd != -1)
1584 close(sock_fd);
1585
1586 if (fatal_err) {
1587 /*
1588 * Get rid of any link-layer type list we allocated.
1589 */
1590 if (handle->dlt_list != NULL)
1591 free(handle->dlt_list);
1592 return -2;
1593 } else
1594 return 0;
1595#else
1596 strncpy(ebuf,
1597 "New packet capturing interface not supported by build "
1598 "environment", PCAP_ERRBUF_SIZE);
1599 return 0;
1600#endif
1601}
1602
1603#ifdef HAVE_PF_PACKET_SOCKETS
1604/*
1605 * Return the index of the given device name. Fill ebuf and return
1606 * -1 on failure.
1607 */
1608static int
1609iface_get_id(int fd, const char *device, char *ebuf)
1610{
1611 struct ifreq ifr;
1612
1613 memset(&ifr, 0, sizeof(ifr));
1614 strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name));
1615
1616 if (ioctl(fd, SIOCGIFINDEX, &ifr) == -1) {
1617 snprintf(ebuf, PCAP_ERRBUF_SIZE,
|
1560 "ioctl: %s", pcap_strerror(errno));
| 1618 "SIOCGIFINDEX: %s", pcap_strerror(errno));
|
1561 return -1;
1562 }
1563
1564 return ifr.ifr_ifindex;
1565}
1566
1567/*
1568 * Bind the socket associated with FD to the given device.
1569 */
1570static int
1571iface_bind(int fd, int ifindex, char *ebuf)
1572{
1573 struct sockaddr_ll sll;
1574 int err;
1575 socklen_t errlen = sizeof(err);
1576
1577 memset(&sll, 0, sizeof(sll));
1578 sll.sll_family = AF_PACKET;
1579 sll.sll_ifindex = ifindex;
1580 sll.sll_protocol = htons(ETH_P_ALL);
1581
1582 if (bind(fd, (struct sockaddr *) &sll, sizeof(sll)) == -1) {
1583 snprintf(ebuf, PCAP_ERRBUF_SIZE,
1584 "bind: %s", pcap_strerror(errno));
1585 return -1;
1586 }
1587
1588 /* Any pending errors, e.g., network is down? */
1589
1590 if (getsockopt(fd, SOL_SOCKET, SO_ERROR, &err, &errlen) == -1) {
1591 snprintf(ebuf, PCAP_ERRBUF_SIZE,
1592 "getsockopt: %s", pcap_strerror(errno));
1593 return -2;
1594 }
1595
1596 if (err > 0) {
1597 snprintf(ebuf, PCAP_ERRBUF_SIZE,
1598 "bind: %s", pcap_strerror(err));
1599 return -2;
1600 }
1601
1602 return 0;
1603}
1604
1605#endif
1606
1607
1608/* ===== Functions to interface to the older kernels ================== */
1609
1610/*
1611 * With older kernels promiscuous mode is kind of interesting because we
1612 * have to reset the interface before exiting. The problem can't really
1613 * be solved without some daemon taking care of managing usage counts.
1614 * If we put the interface into promiscuous mode, we set a flag indicating
1615 * that we must take it out of that mode when the interface is closed,
1616 * and, when closing the interface, if that flag is set we take it out
1617 * of promiscuous mode.
1618 */
1619
1620/*
1621 * List of pcaps for which we turned promiscuous mode on by hand.
1622 * If there are any such pcaps, we arrange to call "pcap_close_all()"
1623 * when we exit, and have it close all of them to turn promiscuous mode
1624 * off.
1625 */
1626static struct pcap *pcaps_to_close;
1627
1628/*
1629 * TRUE if we've already called "atexit()" to cause "pcap_close_all()" to
1630 * be called on exit.
1631 */
1632static int did_atexit;
1633
1634static void pcap_close_all(void)
1635{
1636 struct pcap *handle;
1637
1638 while ((handle = pcaps_to_close) != NULL)
1639 pcap_close(handle);
1640}
1641
1642static void pcap_close_linux( pcap_t *handle )
1643{
1644 struct pcap *p, *prevp;
1645 struct ifreq ifr;
1646
1647 if (handle->md.clear_promisc) {
1648 /*
1649 * We put the interface into promiscuous mode; take
1650 * it out of promiscuous mode.
1651 *
1652 * XXX - if somebody else wants it in promiscuous mode,
1653 * this code cannot know that, so it'll take it out
1654 * of promiscuous mode. That's not fixable in 2.0[.x]
1655 * kernels.
1656 */
1657 memset(&ifr, 0, sizeof(ifr));
1658 strncpy(ifr.ifr_name, handle->md.device, sizeof(ifr.ifr_name));
1659 if (ioctl(handle->fd, SIOCGIFFLAGS, &ifr) == -1) {
1660 fprintf(stderr,
1661 "Can't restore interface flags (SIOCGIFFLAGS failed: %s).\n"
1662 "Please adjust manually.\n"
1663 "Hint: This can't happen with Linux >= 2.2.0.\n",
1664 strerror(errno));
1665 } else {
1666 if (ifr.ifr_flags & IFF_PROMISC) {
1667 /*
1668 * Promiscuous mode is currently on; turn it
1669 * off.
1670 */
1671 ifr.ifr_flags &= ~IFF_PROMISC;
1672 if (ioctl(handle->fd, SIOCSIFFLAGS, &ifr) == -1) {
1673 fprintf(stderr,
1674 "Can't restore interface flags (SIOCSIFFLAGS failed: %s).\n"
1675 "Please adjust manually.\n"
1676 "Hint: This can't happen with Linux >= 2.2.0.\n",
1677 strerror(errno));
1678 }
1679 }
1680 }
1681
1682 /*
1683 * Take this pcap out of the list of pcaps for which we
1684 * have to take the interface out of promiscuous mode.
1685 */
1686 for (p = pcaps_to_close, prevp = NULL; p != NULL;
1687 prevp = p, p = p->md.next) {
1688 if (p == handle) {
1689 /*
1690 * Found it. Remove it from the list.
1691 */
1692 if (prevp == NULL) {
1693 /*
1694 * It was at the head of the list.
1695 */
1696 pcaps_to_close = p->md.next;
1697 } else {
1698 /*
1699 * It was in the middle of the list.
1700 */
1701 prevp->md.next = p->md.next;
1702 }
1703 break;
1704 }
1705 }
1706 }
1707
1708 if (handle->md.device != NULL)
1709 free(handle->md.device);
1710 handle->md.device = NULL;
1711 pcap_close_common(handle);
1712}
1713
1714/*
1715 * Try to open a packet socket using the old kernel interface.
1716 * Returns 0 on failure.
1717 * FIXME: 0 uses to mean success (Sebastian)
1718 */
1719static int
1720live_open_old(pcap_t *handle, const char *device, int promisc,
1721 int to_ms, char *ebuf)
1722{
1723 int arptype;
1724 struct ifreq ifr;
1725
1726 do {
1727 /* Open the socket */
1728
1729 handle->fd = socket(PF_INET, SOCK_PACKET, htons(ETH_P_ALL));
1730 if (handle->fd == -1) {
1731 snprintf(ebuf, PCAP_ERRBUF_SIZE,
1732 "socket: %s", pcap_strerror(errno));
1733 break;
1734 }
1735
1736 /* It worked - we are using the old interface */
1737 handle->md.sock_packet = 1;
1738
1739 /* ...which means we get the link-layer header. */
1740 handle->md.cooked = 0;
1741
1742 /* Bind to the given device */
1743
1744 if (!device) {
1745 strncpy(ebuf, "pcap_open_live: The \"any\" device isn't supported on 2.0[.x]-kernel systems",
1746 PCAP_ERRBUF_SIZE);
1747 break;
1748 }
1749 if (iface_bind_old(handle->fd, device, ebuf) == -1)
1750 break;
1751
1752 /*
1753 * Try to get the link-layer type.
1754 */
1755 arptype = iface_get_arptype(handle->fd, device, ebuf);
1756 if (arptype == -1)
1757 break;
1758
1759 /*
1760 * Try to find the DLT_ type corresponding to that
1761 * link-layer type.
1762 */
1763 map_arphrd_to_dlt(handle, arptype, 0);
1764 if (handle->linktype == -1) {
1765 snprintf(ebuf, PCAP_ERRBUF_SIZE,
1766 "unknown arptype %d", arptype);
1767 break;
1768 }
1769
1770 /* Go to promisc mode if requested */
1771
1772 if (promisc) {
1773 memset(&ifr, 0, sizeof(ifr));
1774 strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name));
1775 if (ioctl(handle->fd, SIOCGIFFLAGS, &ifr) == -1) {
1776 snprintf(ebuf, PCAP_ERRBUF_SIZE,
| 1619 return -1;
1620 }
1621
1622 return ifr.ifr_ifindex;
1623}
1624
1625/*
1626 * Bind the socket associated with FD to the given device.
1627 */
1628static int
1629iface_bind(int fd, int ifindex, char *ebuf)
1630{
1631 struct sockaddr_ll sll;
1632 int err;
1633 socklen_t errlen = sizeof(err);
1634
1635 memset(&sll, 0, sizeof(sll));
1636 sll.sll_family = AF_PACKET;
1637 sll.sll_ifindex = ifindex;
1638 sll.sll_protocol = htons(ETH_P_ALL);
1639
1640 if (bind(fd, (struct sockaddr *) &sll, sizeof(sll)) == -1) {
1641 snprintf(ebuf, PCAP_ERRBUF_SIZE,
1642 "bind: %s", pcap_strerror(errno));
1643 return -1;
1644 }
1645
1646 /* Any pending errors, e.g., network is down? */
1647
1648 if (getsockopt(fd, SOL_SOCKET, SO_ERROR, &err, &errlen) == -1) {
1649 snprintf(ebuf, PCAP_ERRBUF_SIZE,
1650 "getsockopt: %s", pcap_strerror(errno));
1651 return -2;
1652 }
1653
1654 if (err > 0) {
1655 snprintf(ebuf, PCAP_ERRBUF_SIZE,
1656 "bind: %s", pcap_strerror(err));
1657 return -2;
1658 }
1659
1660 return 0;
1661}
1662
1663#endif
1664
1665
1666/* ===== Functions to interface to the older kernels ================== */
1667
1668/*
1669 * With older kernels promiscuous mode is kind of interesting because we
1670 * have to reset the interface before exiting. The problem can't really
1671 * be solved without some daemon taking care of managing usage counts.
1672 * If we put the interface into promiscuous mode, we set a flag indicating
1673 * that we must take it out of that mode when the interface is closed,
1674 * and, when closing the interface, if that flag is set we take it out
1675 * of promiscuous mode.
1676 */
1677
1678/*
1679 * List of pcaps for which we turned promiscuous mode on by hand.
1680 * If there are any such pcaps, we arrange to call "pcap_close_all()"
1681 * when we exit, and have it close all of them to turn promiscuous mode
1682 * off.
1683 */
1684static struct pcap *pcaps_to_close;
1685
1686/*
1687 * TRUE if we've already called "atexit()" to cause "pcap_close_all()" to
1688 * be called on exit.
1689 */
1690static int did_atexit;
1691
1692static void pcap_close_all(void)
1693{
1694 struct pcap *handle;
1695
1696 while ((handle = pcaps_to_close) != NULL)
1697 pcap_close(handle);
1698}
1699
1700static void pcap_close_linux( pcap_t *handle )
1701{
1702 struct pcap *p, *prevp;
1703 struct ifreq ifr;
1704
1705 if (handle->md.clear_promisc) {
1706 /*
1707 * We put the interface into promiscuous mode; take
1708 * it out of promiscuous mode.
1709 *
1710 * XXX - if somebody else wants it in promiscuous mode,
1711 * this code cannot know that, so it'll take it out
1712 * of promiscuous mode. That's not fixable in 2.0[.x]
1713 * kernels.
1714 */
1715 memset(&ifr, 0, sizeof(ifr));
1716 strncpy(ifr.ifr_name, handle->md.device, sizeof(ifr.ifr_name));
1717 if (ioctl(handle->fd, SIOCGIFFLAGS, &ifr) == -1) {
1718 fprintf(stderr,
1719 "Can't restore interface flags (SIOCGIFFLAGS failed: %s).\n"
1720 "Please adjust manually.\n"
1721 "Hint: This can't happen with Linux >= 2.2.0.\n",
1722 strerror(errno));
1723 } else {
1724 if (ifr.ifr_flags & IFF_PROMISC) {
1725 /*
1726 * Promiscuous mode is currently on; turn it
1727 * off.
1728 */
1729 ifr.ifr_flags &= ~IFF_PROMISC;
1730 if (ioctl(handle->fd, SIOCSIFFLAGS, &ifr) == -1) {
1731 fprintf(stderr,
1732 "Can't restore interface flags (SIOCSIFFLAGS failed: %s).\n"
1733 "Please adjust manually.\n"
1734 "Hint: This can't happen with Linux >= 2.2.0.\n",
1735 strerror(errno));
1736 }
1737 }
1738 }
1739
1740 /*
1741 * Take this pcap out of the list of pcaps for which we
1742 * have to take the interface out of promiscuous mode.
1743 */
1744 for (p = pcaps_to_close, prevp = NULL; p != NULL;
1745 prevp = p, p = p->md.next) {
1746 if (p == handle) {
1747 /*
1748 * Found it. Remove it from the list.
1749 */
1750 if (prevp == NULL) {
1751 /*
1752 * It was at the head of the list.
1753 */
1754 pcaps_to_close = p->md.next;
1755 } else {
1756 /*
1757 * It was in the middle of the list.
1758 */
1759 prevp->md.next = p->md.next;
1760 }
1761 break;
1762 }
1763 }
1764 }
1765
1766 if (handle->md.device != NULL)
1767 free(handle->md.device);
1768 handle->md.device = NULL;
1769 pcap_close_common(handle);
1770}
1771
1772/*
1773 * Try to open a packet socket using the old kernel interface.
1774 * Returns 0 on failure.
1775 * FIXME: 0 uses to mean success (Sebastian)
1776 */
1777static int
1778live_open_old(pcap_t *handle, const char *device, int promisc,
1779 int to_ms, char *ebuf)
1780{
1781 int arptype;
1782 struct ifreq ifr;
1783
1784 do {
1785 /* Open the socket */
1786
1787 handle->fd = socket(PF_INET, SOCK_PACKET, htons(ETH_P_ALL));
1788 if (handle->fd == -1) {
1789 snprintf(ebuf, PCAP_ERRBUF_SIZE,
1790 "socket: %s", pcap_strerror(errno));
1791 break;
1792 }
1793
1794 /* It worked - we are using the old interface */
1795 handle->md.sock_packet = 1;
1796
1797 /* ...which means we get the link-layer header. */
1798 handle->md.cooked = 0;
1799
1800 /* Bind to the given device */
1801
1802 if (!device) {
1803 strncpy(ebuf, "pcap_open_live: The \"any\" device isn't supported on 2.0[.x]-kernel systems",
1804 PCAP_ERRBUF_SIZE);
1805 break;
1806 }
1807 if (iface_bind_old(handle->fd, device, ebuf) == -1)
1808 break;
1809
1810 /*
1811 * Try to get the link-layer type.
1812 */
1813 arptype = iface_get_arptype(handle->fd, device, ebuf);
1814 if (arptype == -1)
1815 break;
1816
1817 /*
1818 * Try to find the DLT_ type corresponding to that
1819 * link-layer type.
1820 */
1821 map_arphrd_to_dlt(handle, arptype, 0);
1822 if (handle->linktype == -1) {
1823 snprintf(ebuf, PCAP_ERRBUF_SIZE,
1824 "unknown arptype %d", arptype);
1825 break;
1826 }
1827
1828 /* Go to promisc mode if requested */
1829
1830 if (promisc) {
1831 memset(&ifr, 0, sizeof(ifr));
1832 strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name));
1833 if (ioctl(handle->fd, SIOCGIFFLAGS, &ifr) == -1) {
1834 snprintf(ebuf, PCAP_ERRBUF_SIZE,
|
1777 "ioctl: %s", pcap_strerror(errno));
| 1835 "SIOCGIFFLAGS: %s", pcap_strerror(errno));
|
1778 break;
1779 }
1780 if ((ifr.ifr_flags & IFF_PROMISC) == 0) {
1781 /*
1782 * Promiscuous mode isn't currently on,
1783 * so turn it on, and remember that
1784 * we should turn it off when the
1785 * pcap_t is closed.
1786 */
1787
1788 /*
1789 * If we haven't already done so, arrange
1790 * to have "pcap_close_all()" called when
1791 * we exit.
1792 */
1793 if (!did_atexit) {
1794 if (atexit(pcap_close_all) == -1) {
1795 /*
1796 * "atexit()" failed; don't
1797 * put the interface in
1798 * promiscuous mode, just
1799 * give up.
1800 */
1801 strncpy(ebuf, "atexit failed",
1802 PCAP_ERRBUF_SIZE);
1803 break;
1804 }
1805 did_atexit = 1;
1806 }
1807
1808 ifr.ifr_flags |= IFF_PROMISC;
1809 if (ioctl(handle->fd, SIOCSIFFLAGS, &ifr) == -1) {
1810 snprintf(ebuf, PCAP_ERRBUF_SIZE,
| 1836 break;
1837 }
1838 if ((ifr.ifr_flags & IFF_PROMISC) == 0) {
1839 /*
1840 * Promiscuous mode isn't currently on,
1841 * so turn it on, and remember that
1842 * we should turn it off when the
1843 * pcap_t is closed.
1844 */
1845
1846 /*
1847 * If we haven't already done so, arrange
1848 * to have "pcap_close_all()" called when
1849 * we exit.
1850 */
1851 if (!did_atexit) {
1852 if (atexit(pcap_close_all) == -1) {
1853 /*
1854 * "atexit()" failed; don't
1855 * put the interface in
1856 * promiscuous mode, just
1857 * give up.
1858 */
1859 strncpy(ebuf, "atexit failed",
1860 PCAP_ERRBUF_SIZE);
1861 break;
1862 }
1863 did_atexit = 1;
1864 }
1865
1866 ifr.ifr_flags |= IFF_PROMISC;
1867 if (ioctl(handle->fd, SIOCSIFFLAGS, &ifr) == -1) {
1868 snprintf(ebuf, PCAP_ERRBUF_SIZE,
|
1811 "ioctl: %s",
| 1869 "SIOCSIFFLAGS: %s",
|
1812 pcap_strerror(errno));
1813 break;
1814 }
1815 handle->md.clear_promisc = 1;
1816
1817 /*
1818 * Add this to the list of pcaps
1819 * to close when we exit.
1820 */
1821 handle->md.next = pcaps_to_close;
1822 pcaps_to_close = handle;
1823 }
1824 }
1825
1826 /*
1827 * Default value for offset to align link-layer payload
1828 * on a 4-byte boundary.
1829 */
1830 handle->offset = 0;
1831
1832 return 1;
1833
1834 } while (0);
1835
1836 pcap_close_linux(handle);
1837 return 0;
1838}
1839
1840/*
1841 * Bind the socket associated with FD to the given device using the
1842 * interface of the old kernels.
1843 */
1844static int
1845iface_bind_old(int fd, const char *device, char *ebuf)
1846{
1847 struct sockaddr saddr;
1848 int err;
1849 socklen_t errlen = sizeof(err);
1850
1851 memset(&saddr, 0, sizeof(saddr));
1852 strncpy(saddr.sa_data, device, sizeof(saddr.sa_data));
1853 if (bind(fd, &saddr, sizeof(saddr)) == -1) {
1854 snprintf(ebuf, PCAP_ERRBUF_SIZE,
1855 "bind: %s", pcap_strerror(errno));
1856 return -1;
1857 }
1858
1859 /* Any pending errors, e.g., network is down? */
1860
1861 if (getsockopt(fd, SOL_SOCKET, SO_ERROR, &err, &errlen) == -1) {
1862 snprintf(ebuf, PCAP_ERRBUF_SIZE,
1863 "getsockopt: %s", pcap_strerror(errno));
1864 return -1;
1865 }
1866
1867 if (err > 0) {
1868 snprintf(ebuf, PCAP_ERRBUF_SIZE,
1869 "bind: %s", pcap_strerror(err));
1870 return -1;
1871 }
1872
1873 return 0;
1874}
1875
1876
1877/* ===== System calls available on all supported kernels ============== */
1878
1879/*
1880 * Query the kernel for the MTU of the given interface.
1881 */
1882static int
1883iface_get_mtu(int fd, const char *device, char *ebuf)
1884{
1885 struct ifreq ifr;
1886
1887 if (!device)
1888 return BIGGER_THAN_ALL_MTUS;
1889
1890 memset(&ifr, 0, sizeof(ifr));
1891 strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name));
1892
1893 if (ioctl(fd, SIOCGIFMTU, &ifr) == -1) {
1894 snprintf(ebuf, PCAP_ERRBUF_SIZE,
| 1870 pcap_strerror(errno));
1871 break;
1872 }
1873 handle->md.clear_promisc = 1;
1874
1875 /*
1876 * Add this to the list of pcaps
1877 * to close when we exit.
1878 */
1879 handle->md.next = pcaps_to_close;
1880 pcaps_to_close = handle;
1881 }
1882 }
1883
1884 /*
1885 * Default value for offset to align link-layer payload
1886 * on a 4-byte boundary.
1887 */
1888 handle->offset = 0;
1889
1890 return 1;
1891
1892 } while (0);
1893
1894 pcap_close_linux(handle);
1895 return 0;
1896}
1897
1898/*
1899 * Bind the socket associated with FD to the given device using the
1900 * interface of the old kernels.
1901 */
1902static int
1903iface_bind_old(int fd, const char *device, char *ebuf)
1904{
1905 struct sockaddr saddr;
1906 int err;
1907 socklen_t errlen = sizeof(err);
1908
1909 memset(&saddr, 0, sizeof(saddr));
1910 strncpy(saddr.sa_data, device, sizeof(saddr.sa_data));
1911 if (bind(fd, &saddr, sizeof(saddr)) == -1) {
1912 snprintf(ebuf, PCAP_ERRBUF_SIZE,
1913 "bind: %s", pcap_strerror(errno));
1914 return -1;
1915 }
1916
1917 /* Any pending errors, e.g., network is down? */
1918
1919 if (getsockopt(fd, SOL_SOCKET, SO_ERROR, &err, &errlen) == -1) {
1920 snprintf(ebuf, PCAP_ERRBUF_SIZE,
1921 "getsockopt: %s", pcap_strerror(errno));
1922 return -1;
1923 }
1924
1925 if (err > 0) {
1926 snprintf(ebuf, PCAP_ERRBUF_SIZE,
1927 "bind: %s", pcap_strerror(err));
1928 return -1;
1929 }
1930
1931 return 0;
1932}
1933
1934
1935/* ===== System calls available on all supported kernels ============== */
1936
1937/*
1938 * Query the kernel for the MTU of the given interface.
1939 */
1940static int
1941iface_get_mtu(int fd, const char *device, char *ebuf)
1942{
1943 struct ifreq ifr;
1944
1945 if (!device)
1946 return BIGGER_THAN_ALL_MTUS;
1947
1948 memset(&ifr, 0, sizeof(ifr));
1949 strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name));
1950
1951 if (ioctl(fd, SIOCGIFMTU, &ifr) == -1) {
1952 snprintf(ebuf, PCAP_ERRBUF_SIZE,
|
1895 "ioctl: %s", pcap_strerror(errno));
| 1953 "SIOCGIFMTU: %s", pcap_strerror(errno));
|
1896 return -1;
1897 }
1898
1899 return ifr.ifr_mtu;
1900}
1901
1902/*
1903 * Get the hardware type of the given interface as ARPHRD_xxx constant.
1904 */
1905static int
1906iface_get_arptype(int fd, const char *device, char *ebuf)
1907{
1908 struct ifreq ifr;
1909
1910 memset(&ifr, 0, sizeof(ifr));
1911 strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name));
1912
1913 if (ioctl(fd, SIOCGIFHWADDR, &ifr) == -1) {
1914 snprintf(ebuf, PCAP_ERRBUF_SIZE,
| 1954 return -1;
1955 }
1956
1957 return ifr.ifr_mtu;
1958}
1959
1960/*
1961 * Get the hardware type of the given interface as ARPHRD_xxx constant.
1962 */
1963static int
1964iface_get_arptype(int fd, const char *device, char *ebuf)
1965{
1966 struct ifreq ifr;
1967
1968 memset(&ifr, 0, sizeof(ifr));
1969 strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name));
1970
1971 if (ioctl(fd, SIOCGIFHWADDR, &ifr) == -1) {
1972 snprintf(ebuf, PCAP_ERRBUF_SIZE,
|
1915 "ioctl: %s", pcap_strerror(errno));
| 1973 "SIOCGIFHWADDR: %s", pcap_strerror(errno));
|
1916 return -1;
1917 }
1918
1919 return ifr.ifr_hwaddr.sa_family;
1920}
1921
1922#ifdef SO_ATTACH_FILTER
1923static int
1924fix_program(pcap_t *handle, struct sock_fprog *fcode)
1925{
1926 size_t prog_size;
1927 register int i;
1928 register struct bpf_insn *p;
1929 struct bpf_insn *f;
1930 int len;
1931
1932 /*
1933 * Make a copy of the filter, and modify that copy if
1934 * necessary.
1935 */
1936 prog_size = sizeof(*handle->fcode.bf_insns) * handle->fcode.bf_len;
1937 len = handle->fcode.bf_len;
1938 f = (struct bpf_insn *)malloc(prog_size);
1939 if (f == NULL) {
1940 snprintf(handle->errbuf, sizeof(handle->errbuf),
1941 "malloc: %s", pcap_strerror(errno));
1942 return -1;
1943 }
1944 memcpy(f, handle->fcode.bf_insns, prog_size);
1945 fcode->len = len;
1946 fcode->filter = (struct sock_filter *) f;
1947
1948 for (i = 0; i < len; ++i) {
1949 p = &f[i];
1950 /*
1951 * What type of instruction is this?
1952 */
1953 switch (BPF_CLASS(p->code)) {
1954
1955 case BPF_RET:
1956 /*
1957 * It's a return instruction; is the snapshot
1958 * length a constant, rather than the contents
1959 * of the accumulator?
1960 */
1961 if (BPF_MODE(p->code) == BPF_K) {
1962 /*
1963 * Yes - if the value to be returned,
1964 * i.e. the snapshot length, is anything
1965 * other than 0, make it 65535, so that
1966 * the packet is truncated by "recvfrom()",
1967 * not by the filter.
1968 *
1969 * XXX - there's nothing we can easily do
1970 * if it's getting the value from the
1971 * accumulator; we'd have to insert
1972 * code to force non-zero values to be
1973 * 65535.
1974 */
1975 if (p->k != 0)
1976 p->k = 65535;
1977 }
1978 break;
1979
1980 case BPF_LD:
1981 case BPF_LDX:
1982 /*
1983 * It's a load instruction; is it loading
1984 * from the packet?
1985 */
1986 switch (BPF_MODE(p->code)) {
1987
1988 case BPF_ABS:
1989 case BPF_IND:
1990 case BPF_MSH:
1991 /*
1992 * Yes; are we in cooked mode?
1993 */
1994 if (handle->md.cooked) {
1995 /*
1996 * Yes, so we need to fix this
1997 * instruction.
1998 */
1999 if (fix_offset(p) < 0) {
2000 /*
2001 * We failed to do so.
2002 * Return 0, so our caller
2003 * knows to punt to userland.
2004 */
2005 return 0;
2006 }
2007 }
2008 break;
2009 }
2010 break;
2011 }
2012 }
2013 return 1; /* we succeeded */
2014}
2015
2016static int
2017fix_offset(struct bpf_insn *p)
2018{
2019 /*
2020 * What's the offset?
2021 */
2022 if (p->k >= SLL_HDR_LEN) {
2023 /*
2024 * It's within the link-layer payload; that starts at an
2025 * offset of 0, as far as the kernel packet filter is
2026 * concerned, so subtract the length of the link-layer
2027 * header.
2028 */
2029 p->k -= SLL_HDR_LEN;
2030 } else if (p->k == 14) {
2031 /*
2032 * It's the protocol field; map it to the special magic
2033 * kernel offset for that field.
2034 */
2035 p->k = SKF_AD_OFF + SKF_AD_PROTOCOL;
2036 } else {
2037 /*
2038 * It's within the header, but it's not one of those
2039 * fields; we can't do that in the kernel, so punt
2040 * to userland.
2041 */
2042 return -1;
2043 }
2044 return 0;
2045}
2046
2047static int
2048set_kernel_filter(pcap_t *handle, struct sock_fprog *fcode)
2049{
2050 int total_filter_on = 0;
2051 int save_mode;
2052 int ret;
2053 int save_errno;
2054
2055 /*
2056 * The socket filter code doesn't discard all packets queued
2057 * up on the socket when the filter is changed; this means
2058 * that packets that don't match the new filter may show up
2059 * after the new filter is put onto the socket, if those
2060 * packets haven't yet been read.
2061 *
2062 * This means, for example, that if you do a tcpdump capture
2063 * with a filter, the first few packets in the capture might
2064 * be packets that wouldn't have passed the filter.
2065 *
2066 * We therefore discard all packets queued up on the socket
2067 * when setting a kernel filter. (This isn't an issue for
2068 * userland filters, as the userland filtering is done after
2069 * packets are queued up.)
2070 *
2071 * To flush those packets, we put the socket in read-only mode,
2072 * and read packets from the socket until there are no more to
2073 * read.
2074 *
2075 * In order to keep that from being an infinite loop - i.e.,
2076 * to keep more packets from arriving while we're draining
2077 * the queue - we put the "total filter", which is a filter
2078 * that rejects all packets, onto the socket before draining
2079 * the queue.
2080 *
2081 * This code deliberately ignores any errors, so that you may
2082 * get bogus packets if an error occurs, rather than having
2083 * the filtering done in userland even if it could have been
2084 * done in the kernel.
2085 */
2086 if (setsockopt(handle->fd, SOL_SOCKET, SO_ATTACH_FILTER,
2087 &total_fcode, sizeof(total_fcode)) == 0) {
2088 char drain[1];
2089
2090 /*
2091 * Note that we've put the total filter onto the socket.
2092 */
2093 total_filter_on = 1;
2094
2095 /*
2096 * Save the socket's current mode, and put it in
2097 * non-blocking mode; we drain it by reading packets
2098 * until we get an error (which is normally a
2099 * "nothing more to be read" error).
2100 */
2101 save_mode = fcntl(handle->fd, F_GETFL, 0);
2102 if (save_mode != -1 &&
2103 fcntl(handle->fd, F_SETFL, save_mode | O_NONBLOCK) >= 0) {
2104 while (recv(handle->fd, &drain, sizeof drain,
2105 MSG_TRUNC) >= 0)
2106 ;
2107 save_errno = errno;
2108 fcntl(handle->fd, F_SETFL, save_mode);
2109 if (save_errno != EAGAIN) {
2110 /* Fatal error */
2111 reset_kernel_filter(handle);
2112 snprintf(handle->errbuf, sizeof(handle->errbuf),
2113 "recv: %s", pcap_strerror(save_errno));
2114 return -2;
2115 }
2116 }
2117 }
2118
2119 /*
2120 * Now attach the new filter.
2121 */
2122 ret = setsockopt(handle->fd, SOL_SOCKET, SO_ATTACH_FILTER,
2123 fcode, sizeof(*fcode));
2124 if (ret == -1 && total_filter_on) {
2125 /*
2126 * Well, we couldn't set that filter on the socket,
2127 * but we could set the total filter on the socket.
2128 *
2129 * This could, for example, mean that the filter was
2130 * too big to put into the kernel, so we'll have to
2131 * filter in userland; in any case, we'll be doing
2132 * filtering in userland, so we need to remove the
2133 * total filter so we see packets.
2134 */
2135 save_errno = errno;
2136
2137 /*
2138 * XXX - if this fails, we're really screwed;
2139 * we have the total filter on the socket,
2140 * and it won't come off. What do we do then?
2141 */
2142 reset_kernel_filter(handle);
2143
2144 errno = save_errno;
2145 }
2146 return ret;
2147}
2148
2149static int
2150reset_kernel_filter(pcap_t *handle)
2151{
| 1974 return -1;
1975 }
1976
1977 return ifr.ifr_hwaddr.sa_family;
1978}
1979
1980#ifdef SO_ATTACH_FILTER
1981static int
1982fix_program(pcap_t *handle, struct sock_fprog *fcode)
1983{
1984 size_t prog_size;
1985 register int i;
1986 register struct bpf_insn *p;
1987 struct bpf_insn *f;
1988 int len;
1989
1990 /*
1991 * Make a copy of the filter, and modify that copy if
1992 * necessary.
1993 */
1994 prog_size = sizeof(*handle->fcode.bf_insns) * handle->fcode.bf_len;
1995 len = handle->fcode.bf_len;
1996 f = (struct bpf_insn *)malloc(prog_size);
1997 if (f == NULL) {
1998 snprintf(handle->errbuf, sizeof(handle->errbuf),
1999 "malloc: %s", pcap_strerror(errno));
2000 return -1;
2001 }
2002 memcpy(f, handle->fcode.bf_insns, prog_size);
2003 fcode->len = len;
2004 fcode->filter = (struct sock_filter *) f;
2005
2006 for (i = 0; i < len; ++i) {
2007 p = &f[i];
2008 /*
2009 * What type of instruction is this?
2010 */
2011 switch (BPF_CLASS(p->code)) {
2012
2013 case BPF_RET:
2014 /*
2015 * It's a return instruction; is the snapshot
2016 * length a constant, rather than the contents
2017 * of the accumulator?
2018 */
2019 if (BPF_MODE(p->code) == BPF_K) {
2020 /*
2021 * Yes - if the value to be returned,
2022 * i.e. the snapshot length, is anything
2023 * other than 0, make it 65535, so that
2024 * the packet is truncated by "recvfrom()",
2025 * not by the filter.
2026 *
2027 * XXX - there's nothing we can easily do
2028 * if it's getting the value from the
2029 * accumulator; we'd have to insert
2030 * code to force non-zero values to be
2031 * 65535.
2032 */
2033 if (p->k != 0)
2034 p->k = 65535;
2035 }
2036 break;
2037
2038 case BPF_LD:
2039 case BPF_LDX:
2040 /*
2041 * It's a load instruction; is it loading
2042 * from the packet?
2043 */
2044 switch (BPF_MODE(p->code)) {
2045
2046 case BPF_ABS:
2047 case BPF_IND:
2048 case BPF_MSH:
2049 /*
2050 * Yes; are we in cooked mode?
2051 */
2052 if (handle->md.cooked) {
2053 /*
2054 * Yes, so we need to fix this
2055 * instruction.
2056 */
2057 if (fix_offset(p) < 0) {
2058 /*
2059 * We failed to do so.
2060 * Return 0, so our caller
2061 * knows to punt to userland.
2062 */
2063 return 0;
2064 }
2065 }
2066 break;
2067 }
2068 break;
2069 }
2070 }
2071 return 1; /* we succeeded */
2072}
2073
2074static int
2075fix_offset(struct bpf_insn *p)
2076{
2077 /*
2078 * What's the offset?
2079 */
2080 if (p->k >= SLL_HDR_LEN) {
2081 /*
2082 * It's within the link-layer payload; that starts at an
2083 * offset of 0, as far as the kernel packet filter is
2084 * concerned, so subtract the length of the link-layer
2085 * header.
2086 */
2087 p->k -= SLL_HDR_LEN;
2088 } else if (p->k == 14) {
2089 /*
2090 * It's the protocol field; map it to the special magic
2091 * kernel offset for that field.
2092 */
2093 p->k = SKF_AD_OFF + SKF_AD_PROTOCOL;
2094 } else {
2095 /*
2096 * It's within the header, but it's not one of those
2097 * fields; we can't do that in the kernel, so punt
2098 * to userland.
2099 */
2100 return -1;
2101 }
2102 return 0;
2103}
2104
2105static int
2106set_kernel_filter(pcap_t *handle, struct sock_fprog *fcode)
2107{
2108 int total_filter_on = 0;
2109 int save_mode;
2110 int ret;
2111 int save_errno;
2112
2113 /*
2114 * The socket filter code doesn't discard all packets queued
2115 * up on the socket when the filter is changed; this means
2116 * that packets that don't match the new filter may show up
2117 * after the new filter is put onto the socket, if those
2118 * packets haven't yet been read.
2119 *
2120 * This means, for example, that if you do a tcpdump capture
2121 * with a filter, the first few packets in the capture might
2122 * be packets that wouldn't have passed the filter.
2123 *
2124 * We therefore discard all packets queued up on the socket
2125 * when setting a kernel filter. (This isn't an issue for
2126 * userland filters, as the userland filtering is done after
2127 * packets are queued up.)
2128 *
2129 * To flush those packets, we put the socket in read-only mode,
2130 * and read packets from the socket until there are no more to
2131 * read.
2132 *
2133 * In order to keep that from being an infinite loop - i.e.,
2134 * to keep more packets from arriving while we're draining
2135 * the queue - we put the "total filter", which is a filter
2136 * that rejects all packets, onto the socket before draining
2137 * the queue.
2138 *
2139 * This code deliberately ignores any errors, so that you may
2140 * get bogus packets if an error occurs, rather than having
2141 * the filtering done in userland even if it could have been
2142 * done in the kernel.
2143 */
2144 if (setsockopt(handle->fd, SOL_SOCKET, SO_ATTACH_FILTER,
2145 &total_fcode, sizeof(total_fcode)) == 0) {
2146 char drain[1];
2147
2148 /*
2149 * Note that we've put the total filter onto the socket.
2150 */
2151 total_filter_on = 1;
2152
2153 /*
2154 * Save the socket's current mode, and put it in
2155 * non-blocking mode; we drain it by reading packets
2156 * until we get an error (which is normally a
2157 * "nothing more to be read" error).
2158 */
2159 save_mode = fcntl(handle->fd, F_GETFL, 0);
2160 if (save_mode != -1 &&
2161 fcntl(handle->fd, F_SETFL, save_mode | O_NONBLOCK) >= 0) {
2162 while (recv(handle->fd, &drain, sizeof drain,
2163 MSG_TRUNC) >= 0)
2164 ;
2165 save_errno = errno;
2166 fcntl(handle->fd, F_SETFL, save_mode);
2167 if (save_errno != EAGAIN) {
2168 /* Fatal error */
2169 reset_kernel_filter(handle);
2170 snprintf(handle->errbuf, sizeof(handle->errbuf),
2171 "recv: %s", pcap_strerror(save_errno));
2172 return -2;
2173 }
2174 }
2175 }
2176
2177 /*
2178 * Now attach the new filter.
2179 */
2180 ret = setsockopt(handle->fd, SOL_SOCKET, SO_ATTACH_FILTER,
2181 fcode, sizeof(*fcode));
2182 if (ret == -1 && total_filter_on) {
2183 /*
2184 * Well, we couldn't set that filter on the socket,
2185 * but we could set the total filter on the socket.
2186 *
2187 * This could, for example, mean that the filter was
2188 * too big to put into the kernel, so we'll have to
2189 * filter in userland; in any case, we'll be doing
2190 * filtering in userland, so we need to remove the
2191 * total filter so we see packets.
2192 */
2193 save_errno = errno;
2194
2195 /*
2196 * XXX - if this fails, we're really screwed;
2197 * we have the total filter on the socket,
2198 * and it won't come off. What do we do then?
2199 */
2200 reset_kernel_filter(handle);
2201
2202 errno = save_errno;
2203 }
2204 return ret;
2205}
2206
2207static int
2208reset_kernel_filter(pcap_t *handle)
2209{
|
2152 /* setsockopt() barfs unless it get a dummy parameter */
2153 int dummy;
| 2210 /*
2211 * setsockopt() barfs unless it get a dummy parameter.
2212 * valgrind whines unless the value is initialized,
2213 * as it has no idea that setsockopt() ignores its
2214 * parameter.
2215 */
2216 int dummy = 0;
|
2154
2155 return setsockopt(handle->fd, SOL_SOCKET, SO_DETACH_FILTER,
2156 &dummy, sizeof(dummy));
2157}
2158#endif
| 2217
2218 return setsockopt(handle->fd, SOL_SOCKET, SO_DETACH_FILTER,
2219 &dummy, sizeof(dummy));
2220}
2221#endif
|