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