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 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 pcap_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 pcap_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 bpf_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 106 dbus_write(pcap_t *handle, const void *buf, size_t 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 pcap_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 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 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 155 dbus_getnonblock(pcap_t *p) 156 { 157 pcap_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 163 dbus_setnonblock(pcap_t *p, int nonblock _U_) 164 { 165 pcap_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 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 pcap_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 pcap_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 pcap_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 pcap_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 pcap_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 pcap_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 * 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, sizeof (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 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