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 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 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 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 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 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 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 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 * 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 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