The Tcpdump Group git mirrors - libpcap/blob - pcap-dbus.c

   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                         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                 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                     pcap_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, int 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                 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         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         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                         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                         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                         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                         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                 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                                 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, 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