1 /* $NetBSD: pcap-dbus.c,v 1.7 2024/09/02 15:33:37 christos Exp $ */
2
3 /*
4 * Copyright (c) 2012 Jakub Zawadzki
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 *
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 3. The name of the author may not be used to endorse or promote
17 * products derived from this software without specific prior written
18 * permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
21 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
22 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
23 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
24 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
25 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
26 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
27 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
28 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
29 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
30 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
31 */
32
33 #include <sys/cdefs.h>
34 __RCSID("$NetBSD: pcap-dbus.c,v 1.7 2024/09/02 15:33:37 christos Exp $");
35
36 #include <config.h>
37
38 #include <string.h>
39
40 #include <time.h>
41 #include <sys/time.h>
42
43 #include <dbus/dbus.h>
44
45 #include "pcap-int.h"
46 #include "pcap-dbus.h"
47
48 /*
49 * Private data for capturing on D-Bus.
50 */
51 struct pcap_dbus {
52 DBusConnection *conn;
53 u_int packets_read; /* count of packets read */
54 };
55
56 static int
dbus_read(pcap_t * handle,int max_packets _U_,pcap_handler callback,u_char * user)57 dbus_read(pcap_t *handle, int max_packets _U_, pcap_handler callback, u_char *user)
58 {
59 struct pcap_dbus *handlep = handle->priv;
60
61 struct pcap_pkthdr pkth;
62 DBusMessage *message;
63
64 char *raw_msg;
65 int raw_msg_len;
66
67 int count = 0;
68
69 message = dbus_connection_pop_message(handlep->conn);
70
71 while (!message) {
72 /* XXX handle->opt.timeout = timeout_ms; */
73 if (!dbus_connection_read_write(handlep->conn, 100)) {
74 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Connection closed");
75 return -1;
76 }
77
78 if (handle->break_loop) {
79 handle->break_loop = 0;
80 return -2;
81 }
82
83 message = dbus_connection_pop_message(handlep->conn);
84 }
85
86 if (dbus_message_is_signal(message, DBUS_INTERFACE_LOCAL, "Disconnected")) {
87 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Disconnected");
88 return -1;
89 }
90
91 if (dbus_message_marshal(message, &raw_msg, &raw_msg_len)) {
92 pkth.caplen = pkth.len = raw_msg_len;
93 /* pkth.caplen = min (payload_len, handle->snapshot); */
94
95 gettimeofday(&pkth.ts, NULL);
96 if (handle->fcode.bf_insns == NULL ||
97 pcapint_filter(handle->fcode.bf_insns, (u_char *)raw_msg, pkth.len, pkth.caplen)) {
98 handlep->packets_read++;
99 callback(user, &pkth, (u_char *)raw_msg);
100 count++;
101 }
102
103 dbus_free(raw_msg);
104 }
105 return count;
106 }
107
108 static int
dbus_write(pcap_t * handle,const void * buf,int size)109 dbus_write(pcap_t *handle, const void *buf, int size)
110 {
111 /* XXX, not tested */
112 struct pcap_dbus *handlep = handle->priv;
113
114 DBusError error = DBUS_ERROR_INIT;
115 DBusMessage *msg;
116
117 if (!(msg = dbus_message_demarshal(buf, size, &error))) {
118 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "dbus_message_demarshal() failed: %s", error.message);
119 dbus_error_free(&error);
120 return -1;
121 }
122
123 dbus_connection_send(handlep->conn, msg, NULL);
124 dbus_connection_flush(handlep->conn);
125
126 dbus_message_unref(msg);
127 return 0;
128 }
129
130 static int
dbus_stats(pcap_t * handle,struct pcap_stat * stats)131 dbus_stats(pcap_t *handle, struct pcap_stat *stats)
132 {
133 struct pcap_dbus *handlep = handle->priv;
134
135 stats->ps_recv = handlep->packets_read;
136 stats->ps_drop = 0;
137 stats->ps_ifdrop = 0;
138 return 0;
139 }
140
141 static void
dbus_cleanup(pcap_t * handle)142 dbus_cleanup(pcap_t *handle)
143 {
144 struct pcap_dbus *handlep = handle->priv;
145
146 dbus_connection_unref(handlep->conn);
147
148 pcapint_cleanup_live_common(handle);
149 }
150
151 /*
152 * We don't support non-blocking mode. I'm not sure what we'd
153 * do to support it and, given that we don't support select()/
154 * poll()/epoll_wait()/kevent() etc., it probably doesn't
155 * matter.
156 */
157 static int
dbus_getnonblock(pcap_t * p)158 dbus_getnonblock(pcap_t *p)
159 {
160 snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
161 "Non-blocking mode isn't supported for capturing on D-Bus");
162 return (-1);
163 }
164
165 static int
dbus_setnonblock(pcap_t * p,int nonblock _U_)166 dbus_setnonblock(pcap_t *p, int nonblock _U_)
167 {
168 snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
169 "Non-blocking mode isn't supported for capturing on D-Bus");
170 return (-1);
171 }
172
173 static int
dbus_activate(pcap_t * handle)174 dbus_activate(pcap_t *handle)
175 {
176 #define EAVESDROPPING_RULE "eavesdrop=true,"
177
178 static const char *rules[] = {
179 EAVESDROPPING_RULE "type='signal'",
180 EAVESDROPPING_RULE "type='method_call'",
181 EAVESDROPPING_RULE "type='method_return'",
182 EAVESDROPPING_RULE "type='error'",
183 };
184
185 #define N_RULES sizeof(rules)/sizeof(rules[0])
186
187 struct pcap_dbus *handlep = handle->priv;
188 const char *dev = handle->opt.device;
189
190 DBusError error = DBUS_ERROR_INIT;
191 u_int i;
192
193 if (strcmp(dev, "dbus-system") == 0) {
194 if (!(handlep->conn = dbus_bus_get(DBUS_BUS_SYSTEM, &error))) {
195 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Failed to get system bus: %s", error.message);
196 dbus_error_free(&error);
197 return PCAP_ERROR;
198 }
199
200 } else if (strcmp(dev, "dbus-session") == 0) {
201 if (!(handlep->conn = dbus_bus_get(DBUS_BUS_SESSION, &error))) {
202 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Failed to get session bus: %s", error.message);
203 dbus_error_free(&error);
204 return PCAP_ERROR;
205 }
206
207 } else if (strncmp(dev, "dbus://", 7) == 0) {
208 const char *addr = dev + 7;
209
210 if (!(handlep->conn = dbus_connection_open(addr, &error))) {
211 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Failed to open connection to: %s: %s", addr, error.message);
212 dbus_error_free(&error);
213 return PCAP_ERROR;
214 }
215
216 if (!dbus_bus_register(handlep->conn, &error)) {
217 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Failed to register bus %s: %s\n", addr, error.message);
218 dbus_error_free(&error);
219 return PCAP_ERROR;
220 }
221
222 } else {
223 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Can't get bus address from %s", handle->opt.device);
224 return PCAP_ERROR;
225 }
226
227 /* Initialize some components of the pcap structure. */
228 handle->bufsize = 0;
229 handle->offset = 0;
230 handle->linktype = DLT_DBUS;
231 handle->read_op = dbus_read;
232 handle->inject_op = dbus_write;
233 handle->setfilter_op = pcapint_install_bpf_program; /* XXX, later add support for dbus_bus_add_match() */
234 handle->setdirection_op = NULL;
235 handle->set_datalink_op = NULL; /* can't change data link type */
236 handle->getnonblock_op = dbus_getnonblock;
237 handle->setnonblock_op = dbus_setnonblock;
238 handle->stats_op = dbus_stats;
239 handle->cleanup_op = dbus_cleanup;
240
241 #ifndef _WIN32
242 /*
243 * Unfortunately, trying to do a select()/poll()/epoll_wait()/
244 * kevent()/etc. on a D-Bus connection isn't a simple
245 * case of "give me an FD on which to wait".
246 *
247 * Apparently, you have to register "add watch", "remove watch",
248 * and "toggle watch" functions with
249 * dbus_connection_set_watch_functions(),
250 * keep a *set* of FDs, add to that set in the "add watch"
251 * function, subtract from it in the "remove watch" function,
252 * and either add to or subtract from that set in the "toggle
253 * watch" function, and do the wait on *all* of the FDs in the
254 * set. (Yes, you need the "toggle watch" function, so that
255 * the main loop doesn't itself need to check for whether
256 * a given watch is enabled or disabled - most libpcap programs
257 * know nothing about D-Bus and shouldn't *have* to know anything
258 * about D-Bus other than how to decode D-Bus messages.)
259 *
260 * Implementing that would require considerable changes in
261 * the way libpcap exports "selectable FDs" to its client.
262 * Until that's done, we just say "you can't do that".
263 */
264 handle->selectable_fd = handle->fd = -1;
265 #endif
266
267 if (handle->opt.rfmon) {
268 /*
269 * Monitor mode doesn't apply to dbus connections.
270 */
271 dbus_cleanup(handle);
272 return PCAP_ERROR_RFMON_NOTSUP;
273 }
274
275 /*
276 * Turn a negative snapshot value (invalid), a snapshot value of
277 * 0 (unspecified), or a value bigger than the normal maximum
278 * value, into the maximum message length for D-Bus (128MB).
279 */
280 if (handle->snapshot <= 0 || handle->snapshot > 134217728)
281 handle->snapshot = 134217728;
282
283 /* dbus_connection_set_max_message_size(handlep->conn, handle->snapshot); */
284 if (handle->opt.buffer_size != 0)
285 dbus_connection_set_max_received_size(handlep->conn, handle->opt.buffer_size);
286
287 for (i = 0; i < N_RULES; i++) {
288 dbus_bus_add_match(handlep->conn, rules[i], &error);
289 if (dbus_error_is_set(&error)) {
290 dbus_error_free(&error);
291
292 /* try without eavesdrop */
293 dbus_bus_add_match(handlep->conn, rules[i] + strlen(EAVESDROPPING_RULE), &error);
294 if (dbus_error_is_set(&error)) {
295 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Failed to add bus match: %s\n", error.message);
296 dbus_error_free(&error);
297 dbus_cleanup(handle);
298 return PCAP_ERROR;
299 }
300 }
301 }
302
303 return 0;
304 }
305
306 pcap_t *
dbus_create(const char * device,char * ebuf,int * is_ours)307 dbus_create(const char *device, char *ebuf, int *is_ours)
308 {
309 pcap_t *p;
310
311 if (strcmp(device, "dbus-system") &&
312 strcmp(device, "dbus-session") &&
313 strncmp(device, "dbus://", 7))
314 {
315 *is_ours = 0;
316 return NULL;
317 }
318
319 *is_ours = 1;
320 p = PCAP_CREATE_COMMON(ebuf, struct pcap_dbus);
321 if (p == NULL)
322 return (NULL);
323
324 p->activate_op = dbus_activate;
325 /*
326 * Set these up front, so that, even if our client tries
327 * to set non-blocking mode before we're activated, or
328 * query the state of non-blocking mode, they get an error,
329 * rather than having the non-blocking mode option set
330 * for use later.
331 */
332 p->getnonblock_op = dbus_getnonblock;
333 p->setnonblock_op = dbus_setnonblock;
334 return (p);
335 }
336
337 int
dbus_findalldevs(pcap_if_list_t * devlistp,char * err_str)338 dbus_findalldevs(pcap_if_list_t *devlistp, char *err_str)
339 {
340 /*
341 * The notion of "connected" vs. "disconnected" doesn't apply.
342 * XXX - what about the notions of "up" and "running"?
343 */
344 if (pcapint_add_dev(devlistp, "dbus-system",
345 PCAP_IF_CONNECTION_STATUS_NOT_APPLICABLE, "D-Bus system bus",
346 err_str) == NULL)
347 return -1;
348 if (pcapint_add_dev(devlistp, "dbus-session",
349 PCAP_IF_CONNECTION_STATUS_NOT_APPLICABLE, "D-Bus session bus",
350 err_str) == NULL)
351 return -1;
352 return 0;
353 }
354
355