1 /*
2 * Copyright (c) 2012 Jakub Zawadzki
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 *
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 * 3. The name of the author may not be used to endorse or promote
15 * products derived from this software without specific prior written
16 * permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
19 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
20 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
21 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
22 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
23 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
24 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
26 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
28 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29 */
30
31 #ifdef HAVE_CONFIG_H
32 #include <config.h>
33 #endif
34
35 #include <string.h>
36
37 #include <time.h>
38 #include <sys/time.h>
39
40 #include <dbus/dbus.h>
41
42 #include "pcap-int.h"
43 #include "pcap-dbus.h"
44
45 /*
46 * Private data for capturing on D-Bus.
47 */
48 struct pcap_dbus {
49 DBusConnection *conn;
50 u_int packets_read; /* count of packets read */
51 };
52
53 static int
dbus_read(pcap_t * handle,int max_packets _U_,pcap_handler callback,u_char * user)54 dbus_read(pcap_t *handle, int max_packets _U_, pcap_handler callback, u_char *user)
55 {
56 struct pcap_dbus *handlep = handle->priv;
57
58 struct pcap_pkthdr pkth;
59 DBusMessage *message;
60
61 char *raw_msg;
62 int raw_msg_len;
63
64 int count = 0;
65
66 message = dbus_connection_pop_message(handlep->conn);
67
68 while (!message) {
69 /* XXX handle->opt.timeout = timeout_ms; */
70 if (!dbus_connection_read_write(handlep->conn, 100)) {
71 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Connection closed");
72 return -1;
73 }
74
75 if (handle->break_loop) {
76 handle->break_loop = 0;
77 return -2;
78 }
79
80 message = dbus_connection_pop_message(handlep->conn);
81 }
82
83 if (dbus_message_is_signal(message, DBUS_INTERFACE_LOCAL, "Disconnected")) {
84 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Disconnected");
85 return -1;
86 }
87
88 if (dbus_message_marshal(message, &raw_msg, &raw_msg_len)) {
89 pkth.caplen = pkth.len = raw_msg_len;
90 /* pkth.caplen = min (payload_len, handle->snapshot); */
91
92 gettimeofday(&pkth.ts, NULL);
93 if (handle->fcode.bf_insns == NULL ||
94 pcap_filter(handle->fcode.bf_insns, (u_char *)raw_msg, pkth.len, pkth.caplen)) {
95 handlep->packets_read++;
96 callback(user, &pkth, (u_char *)raw_msg);
97 count++;
98 }
99
100 dbus_free(raw_msg);
101 }
102 return count;
103 }
104
105 static int
dbus_write(pcap_t * handle,const void * buf,int size)106 dbus_write(pcap_t *handle, const void *buf, int size)
107 {
108 /* XXX, not tested */
109 struct pcap_dbus *handlep = handle->priv;
110
111 DBusError error = DBUS_ERROR_INIT;
112 DBusMessage *msg;
113
114 if (!(msg = dbus_message_demarshal(buf, size, &error))) {
115 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "dbus_message_demarshal() failed: %s", error.message);
116 dbus_error_free(&error);
117 return -1;
118 }
119
120 dbus_connection_send(handlep->conn, msg, NULL);
121 dbus_connection_flush(handlep->conn);
122
123 dbus_message_unref(msg);
124 return 0;
125 }
126
127 static int
dbus_stats(pcap_t * handle,struct pcap_stat * stats)128 dbus_stats(pcap_t *handle, struct pcap_stat *stats)
129 {
130 struct pcap_dbus *handlep = handle->priv;
131
132 stats->ps_recv = handlep->packets_read;
133 stats->ps_drop = 0;
134 stats->ps_ifdrop = 0;
135 return 0;
136 }
137
138 static void
dbus_cleanup(pcap_t * handle)139 dbus_cleanup(pcap_t *handle)
140 {
141 struct pcap_dbus *handlep = handle->priv;
142
143 dbus_connection_unref(handlep->conn);
144
145 pcap_cleanup_live_common(handle);
146 }
147
148 /*
149 * We don't support non-blocking mode. I'm not sure what we'd
150 * do to support it and, given that we don't support select()/
151 * poll()/epoll_wait()/kevent() etc., it probably doesn't
152 * matter.
153 */
154 static int
dbus_getnonblock(pcap_t * p)155 dbus_getnonblock(pcap_t *p)
156 {
157 snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
158 "Non-blocking mode isn't supported for capturing on D-Bus");
159 return (-1);
160 }
161
162 static int
dbus_setnonblock(pcap_t * p,int nonblock _U_)163 dbus_setnonblock(pcap_t *p, int nonblock _U_)
164 {
165 snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
166 "Non-blocking mode isn't supported for capturing on D-Bus");
167 return (-1);
168 }
169
170 static int
dbus_activate(pcap_t * handle)171 dbus_activate(pcap_t *handle)
172 {
173 #define EAVESDROPPING_RULE "eavesdrop=true,"
174
175 static const char *rules[] = {
176 EAVESDROPPING_RULE "type='signal'",
177 EAVESDROPPING_RULE "type='method_call'",
178 EAVESDROPPING_RULE "type='method_return'",
179 EAVESDROPPING_RULE "type='error'",
180 };
181
182 #define N_RULES sizeof(rules)/sizeof(rules[0])
183
184 struct pcap_dbus *handlep = handle->priv;
185 const char *dev = handle->opt.device;
186
187 DBusError error = DBUS_ERROR_INIT;
188 u_int i;
189
190 if (strcmp(dev, "dbus-system") == 0) {
191 if (!(handlep->conn = dbus_bus_get(DBUS_BUS_SYSTEM, &error))) {
192 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Failed to get system bus: %s", error.message);
193 dbus_error_free(&error);
194 return PCAP_ERROR;
195 }
196
197 } else if (strcmp(dev, "dbus-session") == 0) {
198 if (!(handlep->conn = dbus_bus_get(DBUS_BUS_SESSION, &error))) {
199 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Failed to get session bus: %s", error.message);
200 dbus_error_free(&error);
201 return PCAP_ERROR;
202 }
203
204 } else if (strncmp(dev, "dbus://", 7) == 0) {
205 const char *addr = dev + 7;
206
207 if (!(handlep->conn = dbus_connection_open(addr, &error))) {
208 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Failed to open connection to: %s: %s", addr, error.message);
209 dbus_error_free(&error);
210 return PCAP_ERROR;
211 }
212
213 if (!dbus_bus_register(handlep->conn, &error)) {
214 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Failed to register bus %s: %s\n", addr, error.message);
215 dbus_error_free(&error);
216 return PCAP_ERROR;
217 }
218
219 } else {
220 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Can't get bus address from %s", handle->opt.device);
221 return PCAP_ERROR;
222 }
223
224 /* Initialize some components of the pcap structure. */
225 handle->bufsize = 0;
226 handle->offset = 0;
227 handle->linktype = DLT_DBUS;
228 handle->read_op = dbus_read;
229 handle->inject_op = dbus_write;
230 handle->setfilter_op = install_bpf_program; /* XXX, later add support for dbus_bus_add_match() */
231 handle->setdirection_op = NULL;
232 handle->set_datalink_op = NULL; /* can't change data link type */
233 handle->getnonblock_op = dbus_getnonblock;
234 handle->setnonblock_op = dbus_setnonblock;
235 handle->stats_op = dbus_stats;
236 handle->cleanup_op = dbus_cleanup;
237
238 #ifndef _WIN32
239 /*
240 * Unfortunately, trying to do a select()/poll()/epoll_wait()/
241 * kevent()/etc. on a D-Bus connection isn't a simple
242 * case of "give me an FD on which to wait".
243 *
244 * Apparently, you have to register "add watch", "remove watch",
245 * and "toggle watch" functions with
246 * dbus_connection_set_watch_functions(),
247 * keep a *set* of FDs, add to that set in the "add watch"
248 * function, subtract from it in the "remove watch" function,
249 * and either add to or subtract from that set in the "toggle
250 * watch" function, and do the wait on *all* of the FDs in the
251 * set. (Yes, you need the "toggle watch" function, so that
252 * the main loop doesn't itself need to check for whether
253 * a given watch is enabled or disabled - most libpcap programs
254 * know nothing about D-Bus and shouldn't *have* to know anything
255 * about D-Bus other than how to decode D-Bus messages.)
256 *
257 * Implementing that would require considerable changes in
258 * the way libpcap exports "selectable FDs" to its client.
259 * Until that's done, we just say "you can't do that".
260 */
261 handle->selectable_fd = handle->fd = -1;
262 #endif
263
264 if (handle->opt.rfmon) {
265 /*
266 * Monitor mode doesn't apply to dbus connections.
267 */
268 dbus_cleanup(handle);
269 return PCAP_ERROR_RFMON_NOTSUP;
270 }
271
272 /*
273 * Turn a negative snapshot value (invalid), a snapshot value of
274 * 0 (unspecified), or a value bigger than the normal maximum
275 * value, into the maximum message length for D-Bus (128MB).
276 */
277 if (handle->snapshot <= 0 || handle->snapshot > 134217728)
278 handle->snapshot = 134217728;
279
280 /* dbus_connection_set_max_message_size(handlep->conn, handle->snapshot); */
281 if (handle->opt.buffer_size != 0)
282 dbus_connection_set_max_received_size(handlep->conn, handle->opt.buffer_size);
283
284 for (i = 0; i < N_RULES; i++) {
285 dbus_bus_add_match(handlep->conn, rules[i], &error);
286 if (dbus_error_is_set(&error)) {
287 dbus_error_free(&error);
288
289 /* try without eavesdrop */
290 dbus_bus_add_match(handlep->conn, rules[i] + strlen(EAVESDROPPING_RULE), &error);
291 if (dbus_error_is_set(&error)) {
292 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Failed to add bus match: %s\n", error.message);
293 dbus_error_free(&error);
294 dbus_cleanup(handle);
295 return PCAP_ERROR;
296 }
297 }
298 }
299
300 return 0;
301 }
302
303 pcap_t *
dbus_create(const char * device,char * ebuf,int * is_ours)304 dbus_create(const char *device, char *ebuf, int *is_ours)
305 {
306 pcap_t *p;
307
308 if (strcmp(device, "dbus-system") &&
309 strcmp(device, "dbus-session") &&
310 strncmp(device, "dbus://", 7))
311 {
312 *is_ours = 0;
313 return NULL;
314 }
315
316 *is_ours = 1;
317 p = PCAP_CREATE_COMMON(ebuf, struct pcap_dbus);
318 if (p == NULL)
319 return (NULL);
320
321 p->activate_op = dbus_activate;
322 /*
323 * Set these up front, so that, even if our client tries
324 * to set non-blocking mode before we're activated, or
325 * query the state of non-blocking mode, they get an error,
326 * rather than having the non-blocking mode option set
327 * for use later.
328 */
329 p->getnonblock_op = dbus_getnonblock;
330 p->setnonblock_op = dbus_setnonblock;
331 return (p);
332 }
333
334 int
dbus_findalldevs(pcap_if_list_t * devlistp,char * err_str)335 dbus_findalldevs(pcap_if_list_t *devlistp, char *err_str)
336 {
337 /*
338 * The notion of "connected" vs. "disconnected" doesn't apply.
339 * XXX - what about the notions of "up" and "running"?
340 */
341 if (add_dev(devlistp, "dbus-system",
342 PCAP_IF_CONNECTION_STATUS_NOT_APPLICABLE, "D-Bus system bus",
343 err_str) == NULL)
344 return -1;
345 if (add_dev(devlistp, "dbus-session",
346 PCAP_IF_CONNECTION_STATUS_NOT_APPLICABLE, "D-Bus session bus",
347 err_str) == NULL)
348 return -1;
349 return 0;
350 }
351
352