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 #include <config.h>
32
33 #include <string.h>
34
35 #include <time.h>
36 #include <sys/time.h>
37
38 #include <dbus/dbus.h>
39
40 #include "pcap-int.h"
41 #include "pcap-dbus.h"
42
43 /*
44 * Private data for capturing on D-Bus.
45 */
46 struct pcap_dbus {
47 DBusConnection *conn;
48 u_int packets_read; /* count of packets read */
49 };
50
51 static int
dbus_read(pcap_t * handle,int max_packets _U_,pcap_handler callback,u_char * user)52 dbus_read(pcap_t *handle, int max_packets _U_, pcap_handler callback, u_char *user)
53 {
54 struct pcap_dbus *handlep = handle->priv;
55
56 struct pcap_pkthdr pkth;
57 DBusMessage *message;
58
59 char *raw_msg;
60 int raw_msg_len;
61
62 int count = 0;
63
64 message = dbus_connection_pop_message(handlep->conn);
65
66 while (!message) {
67 /* XXX handle->opt.timeout = timeout_ms; */
68 if (!dbus_connection_read_write(handlep->conn, 100)) {
69 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Connection closed");
70 return -1;
71 }
72
73 if (handle->break_loop) {
74 handle->break_loop = 0;
75 return -2;
76 }
77
78 message = dbus_connection_pop_message(handlep->conn);
79 }
80
81 if (dbus_message_is_signal(message, DBUS_INTERFACE_LOCAL, "Disconnected")) {
82 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Disconnected");
83 dbus_message_unref(message);
84 return -1;
85 }
86
87 if (dbus_message_marshal(message, &raw_msg, &raw_msg_len)) {
88 pkth.caplen = pkth.len = raw_msg_len;
89 /* pkth.caplen = min (payload_len, handle->snapshot); */
90
91 gettimeofday(&pkth.ts, NULL);
92 if (handle->fcode.bf_insns == NULL ||
93 pcapint_filter(handle->fcode.bf_insns, (u_char *)raw_msg, pkth.len, pkth.caplen)) {
94 handlep->packets_read++;
95 callback(user, &pkth, (u_char *)raw_msg);
96 count++;
97 }
98
99 dbus_free(raw_msg);
100 }
101
102 dbus_message_unref(message);
103
104 return count;
105 }
106
107 static int
dbus_write(pcap_t * handle,const void * buf,int size)108 dbus_write(pcap_t *handle, const void *buf, int size)
109 {
110 /* XXX, not tested */
111 struct pcap_dbus *handlep = handle->priv;
112
113 DBusError error = DBUS_ERROR_INIT;
114 DBusMessage *msg;
115
116 if (!(msg = dbus_message_demarshal(buf, size, &error))) {
117 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "dbus_message_demarshal() failed: %s", error.message);
118 dbus_error_free(&error);
119 return -1;
120 }
121
122 dbus_connection_send(handlep->conn, msg, NULL);
123 dbus_connection_flush(handlep->conn);
124
125 dbus_message_unref(msg);
126 return 0;
127 }
128
129 static int
dbus_stats(pcap_t * handle,struct pcap_stat * stats)130 dbus_stats(pcap_t *handle, struct pcap_stat *stats)
131 {
132 struct pcap_dbus *handlep = handle->priv;
133
134 stats->ps_recv = handlep->packets_read;
135 stats->ps_drop = 0;
136 stats->ps_ifdrop = 0;
137 return 0;
138 }
139
140 static void
dbus_cleanup(pcap_t * handle)141 dbus_cleanup(pcap_t *handle)
142 {
143 struct pcap_dbus *handlep = handle->priv;
144
145 dbus_connection_unref(handlep->conn);
146
147 pcapint_cleanup_live_common(handle);
148 }
149
150 /*
151 * We don't support non-blocking mode. I'm not sure what we'd
152 * do to support it and, given that we don't support select()/
153 * poll()/epoll_wait()/kevent() etc., it probably doesn't
154 * matter.
155 */
156 static int
dbus_getnonblock(pcap_t * p)157 dbus_getnonblock(pcap_t *p)
158 {
159 snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
160 "Non-blocking mode isn't supported for capturing on D-Bus");
161 return (-1);
162 }
163
164 static int
dbus_setnonblock(pcap_t * p,int nonblock _U_)165 dbus_setnonblock(pcap_t *p, int nonblock _U_)
166 {
167 snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
168 "Non-blocking mode isn't supported for capturing on D-Bus");
169 return (-1);
170 }
171
172 static int
dbus_activate(pcap_t * handle)173 dbus_activate(pcap_t *handle)
174 {
175 #define EAVESDROPPING_RULE "eavesdrop=true,"
176
177 static const char *rules[] = {
178 EAVESDROPPING_RULE "type='signal'",
179 EAVESDROPPING_RULE "type='method_call'",
180 EAVESDROPPING_RULE "type='method_return'",
181 EAVESDROPPING_RULE "type='error'",
182 };
183
184 #define N_RULES sizeof(rules)/sizeof(rules[0])
185
186 struct pcap_dbus *handlep = handle->priv;
187 const char *dev = handle->opt.device;
188
189 DBusError error = DBUS_ERROR_INIT;
190 u_int i;
191
192 if (strcmp(dev, "dbus-system") == 0) {
193 if (!(handlep->conn = dbus_bus_get(DBUS_BUS_SYSTEM, &error))) {
194 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Failed to get system bus: %s", error.message);
195 dbus_error_free(&error);
196 return PCAP_ERROR;
197 }
198
199 } else if (strcmp(dev, "dbus-session") == 0) {
200 if (!(handlep->conn = dbus_bus_get(DBUS_BUS_SESSION, &error))) {
201 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Failed to get session bus: %s", error.message);
202 dbus_error_free(&error);
203 return PCAP_ERROR;
204 }
205
206 } else if (strncmp(dev, "dbus://", 7) == 0) {
207 const char *addr = dev + 7;
208
209 if (!(handlep->conn = dbus_connection_open(addr, &error))) {
210 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Failed to open connection to: %s: %s", addr, error.message);
211 dbus_error_free(&error);
212 return PCAP_ERROR;
213 }
214
215 if (!dbus_bus_register(handlep->conn, &error)) {
216 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Failed to register bus %s: %s\n", addr, error.message);
217 dbus_error_free(&error);
218 return PCAP_ERROR;
219 }
220
221 } else {
222 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Can't get bus address from %s", handle->opt.device);
223 return PCAP_ERROR;
224 }
225
226 /* Initialize some components of the pcap structure. */
227 handle->bufsize = 0;
228 handle->offset = 0;
229 handle->linktype = DLT_DBUS;
230 handle->read_op = dbus_read;
231 handle->inject_op = dbus_write;
232 handle->setfilter_op = pcapint_install_bpf_program; /* XXX, later add support for dbus_bus_add_match() */
233 handle->setdirection_op = NULL;
234 handle->set_datalink_op = NULL; /* can't change data link type */
235 handle->getnonblock_op = dbus_getnonblock;
236 handle->setnonblock_op = dbus_setnonblock;
237 handle->stats_op = dbus_stats;
238 handle->cleanup_op = dbus_cleanup;
239
240 #ifndef _WIN32
241 /*
242 * Unfortunately, trying to do a select()/poll()/epoll_wait()/
243 * kevent()/etc. on a D-Bus connection isn't a simple
244 * case of "give me an FD on which to wait".
245 *
246 * Apparently, you have to register "add watch", "remove watch",
247 * and "toggle watch" functions with
248 * dbus_connection_set_watch_functions(),
249 * keep a *set* of FDs, add to that set in the "add watch"
250 * function, subtract from it in the "remove watch" function,
251 * and either add to or subtract from that set in the "toggle
252 * watch" function, and do the wait on *all* of the FDs in the
253 * set. (Yes, you need the "toggle watch" function, so that
254 * the main loop doesn't itself need to check for whether
255 * a given watch is enabled or disabled - most libpcap programs
256 * know nothing about D-Bus and shouldn't *have* to know anything
257 * about D-Bus other than how to decode D-Bus messages.)
258 *
259 * Implementing that would require considerable changes in
260 * the way libpcap exports "selectable FDs" to its client.
261 * Until that's done, we just say "you can't do that".
262 */
263 handle->selectable_fd = handle->fd = -1;
264 #endif
265
266 if (handle->opt.rfmon) {
267 /*
268 * Monitor mode doesn't apply to dbus connections.
269 */
270 dbus_cleanup(handle);
271 return PCAP_ERROR_RFMON_NOTSUP;
272 }
273
274 /*
275 * Turn a negative snapshot value (invalid), a snapshot value of
276 * 0 (unspecified), or a value bigger than the normal maximum
277 * value, into the maximum message length for D-Bus (128MB).
278 */
279 if (handle->snapshot <= 0 || handle->snapshot > 134217728)
280 handle->snapshot = 134217728;
281
282 /* dbus_connection_set_max_message_size(handlep->conn, handle->snapshot); */
283 if (handle->opt.buffer_size != 0)
284 dbus_connection_set_max_received_size(handlep->conn, handle->opt.buffer_size);
285
286 for (i = 0; i < N_RULES; i++) {
287 dbus_bus_add_match(handlep->conn, rules[i], &error);
288 if (dbus_error_is_set(&error)) {
289 dbus_error_free(&error);
290
291 /* try without eavesdrop */
292 dbus_bus_add_match(handlep->conn, rules[i] + strlen(EAVESDROPPING_RULE), &error);
293 if (dbus_error_is_set(&error)) {
294 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Failed to add bus match: %s\n", error.message);
295 dbus_error_free(&error);
296 dbus_cleanup(handle);
297 return PCAP_ERROR;
298 }
299 }
300 }
301
302 return 0;
303 }
304
305 pcap_t *
dbus_create(const char * device,char * ebuf,int * is_ours)306 dbus_create(const char *device, char *ebuf, int *is_ours)
307 {
308 pcap_t *p;
309
310 if (strcmp(device, "dbus-system") &&
311 strcmp(device, "dbus-session") &&
312 strncmp(device, "dbus://", 7))
313 {
314 *is_ours = 0;
315 return NULL;
316 }
317
318 *is_ours = 1;
319 p = PCAP_CREATE_COMMON(ebuf, struct pcap_dbus);
320 if (p == NULL)
321 return (NULL);
322
323 p->activate_op = dbus_activate;
324 /*
325 * Set these up front, so that, even if our client tries
326 * to set non-blocking mode before we're activated, or
327 * query the state of non-blocking mode, they get an error,
328 * rather than having the non-blocking mode option set
329 * for use later.
330 */
331 p->getnonblock_op = dbus_getnonblock;
332 p->setnonblock_op = dbus_setnonblock;
333 return (p);
334 }
335
336 int
dbus_findalldevs(pcap_if_list_t * devlistp,char * err_str)337 dbus_findalldevs(pcap_if_list_t *devlistp, char *err_str)
338 {
339 /*
340 * The notion of "connected" vs. "disconnected" doesn't apply.
341 * XXX - what about the notions of "up" and "running"?
342 */
343 if (pcapint_add_dev(devlistp, "dbus-system",
344 PCAP_IF_CONNECTION_STATUS_NOT_APPLICABLE, "D-Bus system bus",
345 err_str) == NULL)
346 return -1;
347 if (pcapint_add_dev(devlistp, "dbus-session",
348 PCAP_IF_CONNECTION_STATUS_NOT_APPLICABLE, "D-Bus session bus",
349 err_str) == NULL)
350 return -1;
351 return 0;
352 }
353
354