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 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 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 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 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 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 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 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 * 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 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