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 #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