1 /* $NetBSD: pcap-dbus.c,v 1.8 2026/03/18 23:43:20 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 1.8 2026/03/18 23:43:20 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 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 dbus_message_unref(message); 89 return -1; 90 } 91 92 if (dbus_message_marshal(message, &raw_msg, &raw_msg_len)) { 93 pkth.caplen = pkth.len = raw_msg_len; 94 /* pkth.caplen = min (payload_len, handle->snapshot); */ 95 96 gettimeofday(&pkth.ts, NULL); 97 if (handle->fcode.bf_insns == NULL || 98 pcapint_filter(handle->fcode.bf_insns, (u_char *)raw_msg, pkth.len, pkth.caplen)) { 99 handlep->packets_read++; 100 callback(user, &pkth, (u_char *)raw_msg); 101 count++; 102 } 103 104 dbus_free(raw_msg); 105 } 106 107 dbus_message_unref(message); 108 109 return count; 110 } 111 112 static int 113 dbus_write(pcap_t *handle, const void *buf, int size) 114 { 115 /* XXX, not tested */ 116 struct pcap_dbus *handlep = handle->priv; 117 118 DBusError error = DBUS_ERROR_INIT; 119 DBusMessage *msg; 120 121 if (!(msg = dbus_message_demarshal(buf, size, &error))) { 122 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "dbus_message_demarshal() failed: %s", error.message); 123 dbus_error_free(&error); 124 return -1; 125 } 126 127 dbus_connection_send(handlep->conn, msg, NULL); 128 dbus_connection_flush(handlep->conn); 129 130 dbus_message_unref(msg); 131 return 0; 132 } 133 134 static int 135 dbus_stats(pcap_t *handle, struct pcap_stat *stats) 136 { 137 struct pcap_dbus *handlep = handle->priv; 138 139 stats->ps_recv = handlep->packets_read; 140 stats->ps_drop = 0; 141 stats->ps_ifdrop = 0; 142 return 0; 143 } 144 145 static void 146 dbus_cleanup(pcap_t *handle) 147 { 148 struct pcap_dbus *handlep = handle->priv; 149 150 dbus_connection_unref(handlep->conn); 151 152 pcapint_cleanup_live_common(handle); 153 } 154 155 /* 156 * We don't support non-blocking mode. I'm not sure what we'd 157 * do to support it and, given that we don't support select()/ 158 * poll()/epoll_wait()/kevent() etc., it probably doesn't 159 * matter. 160 */ 161 static int 162 dbus_getnonblock(pcap_t *p) 163 { 164 snprintf(p->errbuf, PCAP_ERRBUF_SIZE, 165 "Non-blocking mode isn't supported for capturing on D-Bus"); 166 return (-1); 167 } 168 169 static int 170 dbus_setnonblock(pcap_t *p, int nonblock _U_) 171 { 172 snprintf(p->errbuf, PCAP_ERRBUF_SIZE, 173 "Non-blocking mode isn't supported for capturing on D-Bus"); 174 return (-1); 175 } 176 177 static int 178 dbus_activate(pcap_t *handle) 179 { 180 #define EAVESDROPPING_RULE "eavesdrop=true," 181 182 static const char *rules[] = { 183 EAVESDROPPING_RULE "type='signal'", 184 EAVESDROPPING_RULE "type='method_call'", 185 EAVESDROPPING_RULE "type='method_return'", 186 EAVESDROPPING_RULE "type='error'", 187 }; 188 189 #define N_RULES sizeof(rules)/sizeof(rules[0]) 190 191 struct pcap_dbus *handlep = handle->priv; 192 const char *dev = handle->opt.device; 193 194 DBusError error = DBUS_ERROR_INIT; 195 u_int i; 196 197 if (strcmp(dev, "dbus-system") == 0) { 198 if (!(handlep->conn = dbus_bus_get(DBUS_BUS_SYSTEM, &error))) { 199 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Failed to get system bus: %s", error.message); 200 dbus_error_free(&error); 201 return PCAP_ERROR; 202 } 203 204 } else if (strcmp(dev, "dbus-session") == 0) { 205 if (!(handlep->conn = dbus_bus_get(DBUS_BUS_SESSION, &error))) { 206 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Failed to get session bus: %s", error.message); 207 dbus_error_free(&error); 208 return PCAP_ERROR; 209 } 210 211 } else if (strncmp(dev, "dbus://", 7) == 0) { 212 const char *addr = dev + 7; 213 214 if (!(handlep->conn = dbus_connection_open(addr, &error))) { 215 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Failed to open connection to: %s: %s", addr, error.message); 216 dbus_error_free(&error); 217 return PCAP_ERROR; 218 } 219 220 if (!dbus_bus_register(handlep->conn, &error)) { 221 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Failed to register bus %s: %s\n", addr, error.message); 222 dbus_error_free(&error); 223 return PCAP_ERROR; 224 } 225 226 } else { 227 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Can't get bus address from %s", handle->opt.device); 228 return PCAP_ERROR; 229 } 230 231 /* Initialize some components of the pcap structure. */ 232 handle->bufsize = 0; 233 handle->offset = 0; 234 handle->linktype = DLT_DBUS; 235 handle->read_op = dbus_read; 236 handle->inject_op = dbus_write; 237 handle->setfilter_op = pcapint_install_bpf_program; /* XXX, later add support for dbus_bus_add_match() */ 238 handle->setdirection_op = NULL; 239 handle->set_datalink_op = NULL; /* can't change data link type */ 240 handle->getnonblock_op = dbus_getnonblock; 241 handle->setnonblock_op = dbus_setnonblock; 242 handle->stats_op = dbus_stats; 243 handle->cleanup_op = dbus_cleanup; 244 245 #ifndef _WIN32 246 /* 247 * Unfortunately, trying to do a select()/poll()/epoll_wait()/ 248 * kevent()/etc. on a D-Bus connection isn't a simple 249 * case of "give me an FD on which to wait". 250 * 251 * Apparently, you have to register "add watch", "remove watch", 252 * and "toggle watch" functions with 253 * dbus_connection_set_watch_functions(), 254 * keep a *set* of FDs, add to that set in the "add watch" 255 * function, subtract from it in the "remove watch" function, 256 * and either add to or subtract from that set in the "toggle 257 * watch" function, and do the wait on *all* of the FDs in the 258 * set. (Yes, you need the "toggle watch" function, so that 259 * the main loop doesn't itself need to check for whether 260 * a given watch is enabled or disabled - most libpcap programs 261 * know nothing about D-Bus and shouldn't *have* to know anything 262 * about D-Bus other than how to decode D-Bus messages.) 263 * 264 * Implementing that would require considerable changes in 265 * the way libpcap exports "selectable FDs" to its client. 266 * Until that's done, we just say "you can't do that". 267 */ 268 handle->selectable_fd = handle->fd = -1; 269 #endif 270 271 if (handle->opt.rfmon) { 272 /* 273 * Monitor mode doesn't apply to dbus connections. 274 */ 275 dbus_cleanup(handle); 276 return PCAP_ERROR_RFMON_NOTSUP; 277 } 278 279 /* 280 * Turn a negative snapshot value (invalid), a snapshot value of 281 * 0 (unspecified), or a value bigger than the normal maximum 282 * value, into the maximum message length for D-Bus (128MB). 283 */ 284 if (handle->snapshot <= 0 || handle->snapshot > 134217728) 285 handle->snapshot = 134217728; 286 287 /* dbus_connection_set_max_message_size(handlep->conn, handle->snapshot); */ 288 if (handle->opt.buffer_size != 0) 289 dbus_connection_set_max_received_size(handlep->conn, handle->opt.buffer_size); 290 291 for (i = 0; i < N_RULES; i++) { 292 dbus_bus_add_match(handlep->conn, rules[i], &error); 293 if (dbus_error_is_set(&error)) { 294 dbus_error_free(&error); 295 296 /* try without eavesdrop */ 297 dbus_bus_add_match(handlep->conn, rules[i] + strlen(EAVESDROPPING_RULE), &error); 298 if (dbus_error_is_set(&error)) { 299 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Failed to add bus match: %s\n", error.message); 300 dbus_error_free(&error); 301 dbus_cleanup(handle); 302 return PCAP_ERROR; 303 } 304 } 305 } 306 307 return 0; 308 } 309 310 pcap_t * 311 dbus_create(const char *device, char *ebuf, int *is_ours) 312 { 313 pcap_t *p; 314 315 if (strcmp(device, "dbus-system") && 316 strcmp(device, "dbus-session") && 317 strncmp(device, "dbus://", 7)) 318 { 319 *is_ours = 0; 320 return NULL; 321 } 322 323 *is_ours = 1; 324 p = PCAP_CREATE_COMMON(ebuf, struct pcap_dbus); 325 if (p == NULL) 326 return (NULL); 327 328 p->activate_op = dbus_activate; 329 /* 330 * Set these up front, so that, even if our client tries 331 * to set non-blocking mode before we're activated, or 332 * query the state of non-blocking mode, they get an error, 333 * rather than having the non-blocking mode option set 334 * for use later. 335 */ 336 p->getnonblock_op = dbus_getnonblock; 337 p->setnonblock_op = dbus_setnonblock; 338 return (p); 339 } 340 341 int 342 dbus_findalldevs(pcap_if_list_t *devlistp, char *err_str) 343 { 344 /* 345 * The notion of "connected" vs. "disconnected" doesn't apply. 346 * XXX - what about the notions of "up" and "running"? 347 */ 348 if (pcapint_add_dev(devlistp, "dbus-system", 349 PCAP_IF_CONNECTION_STATUS_NOT_APPLICABLE, "D-Bus system bus", 350 err_str) == NULL) 351 return -1; 352 if (pcapint_add_dev(devlistp, "dbus-session", 353 PCAP_IF_CONNECTION_STATUS_NOT_APPLICABLE, "D-Bus session bus", 354 err_str) == NULL) 355 return -1; 356 return 0; 357 } 358 359
Indexes created Tue May 26 00:24:38 UTC 2026