src/lib/lttng-ctl/channel.c

   1 /*
   2  * Copyright (C) 2017 - Jérémie Galarneau <jeremie.galarneau@efficios.com>
   3  *
   4  * This library is free software; you can redistribute it and/or modify it
   5  * under the terms of the GNU Lesser General Public License, version 2.1 only,
   6  * as published by the Free Software Foundation.
   7  *
   8  * This library is distributed in the hope that it will be useful, but WITHOUT
   9  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  10  * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
  11  * for more details.
  12  *
  13  * You should have received a copy of the GNU Lesser General Public License
  14  * along with this library; if not, write to the Free Software Foundation,
  15  * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  16  */
  17
  18 #include <lttng/notification/notification-internal.h>
  19 #include <lttng/notification/channel-internal.h>
  20 #include <lttng/condition/condition-internal.h>
  21 #include <lttng/endpoint.h>
  22 #include <common/defaults.h>
  23 #include <common/error.h>
  24 #include <common/dynamic-buffer.h>
  25 #include <common/utils.h>
  26 #include <common/defaults.h>
  27 #include <assert.h>
  28 #include "lttng-ctl-helper.h"
  29 #include <sys/select.h>
  30 #include <sys/time.h>
  31
  32 static
  33 int handshake(struct lttng_notification_channel *channel);
  34
  35 /*
  36  * Populates the reception buffer with the next complete message.
  37  * The caller must acquire the channel's lock.
  38  */
  39 static
  40 int receive_message(struct lttng_notification_channel *channel)
  41 {
  42         ssize_t ret;
  43         struct lttng_notification_channel_message msg;
  44
  45         if (lttng_dynamic_buffer_set_size(&channel->reception_buffer, 0)) {
  46                 ret = -1;
  47                 goto end;
  48         }
  49
  50         ret = lttcomm_recv_unix_sock(channel->socket, &msg, sizeof(msg));
  51         if (ret <= 0) {
  52                 ret = -1;
  53                 goto error;
  54         }
  55
  56         if (msg.size > DEFAULT_MAX_NOTIFICATION_CLIENT_MESSAGE_PAYLOAD_SIZE) {
  57                 ret = -1;
  58                 goto error;
  59         }
  60
  61         /* Add message header at buffer's start. */
  62         ret = lttng_dynamic_buffer_append(&channel->reception_buffer, &msg,
  63                         sizeof(msg));
  64         if (ret) {
  65                 goto error;
  66         }
  67
  68         /* Reserve space for the payload. */
  69         ret = lttng_dynamic_buffer_set_size(&channel->reception_buffer,
  70                         channel->reception_buffer.size + msg.size);
  71         if (ret) {
  72                 goto error;
  73         }
  74
  75         /* Receive message payload. */
  76         ret = lttcomm_recv_unix_sock(channel->socket,
  77                         channel->reception_buffer.data + sizeof(msg), msg.size);
  78         if (ret < (ssize_t) msg.size) {
  79                 ret = -1;
  80                 goto error;
  81         }
  82         ret = 0;
  83 end:
  84         return ret;
  85 error:
  86         if (lttng_dynamic_buffer_set_size(&channel->reception_buffer, 0)) {
  87                 ret = -1;
  88         }
  89         goto end;
  90 }
  91
  92 static
  93 enum lttng_notification_channel_message_type get_current_message_type(
  94                 struct lttng_notification_channel *channel)
  95 {
  96         struct lttng_notification_channel_message *msg;
  97
  98         assert(channel->reception_buffer.size >= sizeof(*msg));
  99
 100         msg = (struct lttng_notification_channel_message *)
 101                         channel->reception_buffer.data;
 102         return (enum lttng_notification_channel_message_type) msg->type;
 103 }
 104
 105 static
 106 struct lttng_notification *create_notification_from_current_message(
 107                 struct lttng_notification_channel *channel)
 108 {
 109         ssize_t ret;
 110         struct lttng_notification *notification = NULL;
 111         struct lttng_buffer_view view;
 112
 113         if (channel->reception_buffer.size <=
 114                         sizeof(struct lttng_notification_channel_message)) {
 115                 goto end;
 116         }
 117
 118         view = lttng_buffer_view_from_dynamic_buffer(&channel->reception_buffer,
 119                         sizeof(struct lttng_notification_channel_message), -1);
 120
 121         ret = lttng_notification_create_from_buffer(&view, &notification);
 122         if (ret != channel->reception_buffer.size -
 123                         sizeof(struct lttng_notification_channel_message)) {
 124                 lttng_notification_destroy(notification);
 125                 notification = NULL;
 126                 goto end;
 127         }
 128 end:
 129         return notification;
 130 }
 131
 132 struct lttng_notification_channel *lttng_notification_channel_create(
 133                 struct lttng_endpoint *endpoint)
 134 {
 135         int fd, ret;
 136         bool is_in_tracing_group = false, is_root = false;
 137         char *sock_path = NULL;
 138         struct lttng_notification_channel *channel = NULL;
 139
 140         if (!endpoint ||
 141                         endpoint != lttng_session_daemon_notification_endpoint) {
 142                 goto end;
 143         }
 144
 145         sock_path = zmalloc(LTTNG_PATH_MAX);
 146         if (!sock_path) {
 147                 goto end;
 148         }
 149
 150         channel = zmalloc(sizeof(struct lttng_notification_channel));
 151         if (!channel) {
 152                 goto end;
 153         }
 154         channel->socket = -1;
 155         pthread_mutex_init(&channel->lock, NULL);
 156         lttng_dynamic_buffer_init(&channel->reception_buffer);
 157         CDS_INIT_LIST_HEAD(&channel->pending_notifications.list);
 158
 159         is_root = (getuid() == 0);
 160         if (!is_root) {
 161                 is_in_tracing_group = lttng_check_tracing_group();
 162         }
 163
 164         if (is_root || is_in_tracing_group) {
 165                 lttng_ctl_copy_string(sock_path,
 166                                 DEFAULT_GLOBAL_NOTIFICATION_CHANNEL_UNIX_SOCK,
 167                                 LTTNG_PATH_MAX);
 168                 ret = lttcomm_connect_unix_sock(sock_path);
 169                 if (ret >= 0) {
 170                         fd = ret;
 171                         goto set_fd;
 172                 }
 173         }
 174
 175         /* Fallback to local session daemon. */
 176         ret = snprintf(sock_path, LTTNG_PATH_MAX,
 177                         DEFAULT_HOME_NOTIFICATION_CHANNEL_UNIX_SOCK,
 178                         utils_get_home_dir());
 179         if (ret < 0 || ret >= LTTNG_PATH_MAX) {
 180                 goto error;
 181         }
 182
 183         ret = lttcomm_connect_unix_sock(sock_path);
 184         if (ret < 0) {
 185                 goto error;
 186         }
 187         fd = ret;
 188
 189 set_fd:
 190         channel->socket = fd;
 191
 192         ret = handshake(channel);
 193         if (ret) {
 194                 goto error;
 195         }
 196 end:
 197         free(sock_path);
 198         return channel;
 199 error:
 200         lttng_notification_channel_destroy(channel);
 201         channel = NULL;
 202         goto end;
 203 }
 204
 205 enum lttng_notification_channel_status
 206 lttng_notification_channel_get_next_notification(
 207                 struct lttng_notification_channel *channel,
 208                 struct lttng_notification **_notification)
 209 {
 210         int ret;
 211         struct lttng_notification *notification = NULL;
 212         enum lttng_notification_channel_status status =
 213                         LTTNG_NOTIFICATION_CHANNEL_STATUS_OK;
 214
 215         if (!channel || !_notification) {
 216                 status = LTTNG_NOTIFICATION_CHANNEL_STATUS_INVALID;
 217                 goto end;
 218         }
 219
 220         pthread_mutex_lock(&channel->lock);
 221
 222         if (channel->pending_notifications.count) {
 223                 struct pending_notification *pending_notification;
 224
 225                 assert(!cds_list_empty(&channel->pending_notifications.list));
 226
 227                 /* Deliver one of the pending notifications. */
 228                 pending_notification = cds_list_first_entry(
 229                                 &channel->pending_notifications.list,
 230                                 struct pending_notification,
 231                                 node);
 232                 notification = pending_notification->notification;
 233                 if (!notification) {
 234                         status = LTTNG_NOTIFICATION_CHANNEL_STATUS_NOTIFICATIONS_DROPPED;
 235                 }
 236                 cds_list_del(&pending_notification->node);
 237                 channel->pending_notifications.count--;
 238                 free(pending_notification);
 239                 goto end_unlock;
 240         }
 241
 242         ret = receive_message(channel);
 243         if (ret) {
 244                 status = LTTNG_NOTIFICATION_CHANNEL_STATUS_ERROR;
 245                 goto end_unlock;
 246         }
 247
 248         switch (get_current_message_type(channel)) {
 249         case LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_NOTIFICATION:
 250                 notification = create_notification_from_current_message(
 251                                 channel);
 252                 if (!notification) {
 253                         status = LTTNG_NOTIFICATION_CHANNEL_STATUS_ERROR;
 254                         goto end_unlock;
 255                 }
 256                 break;
 257         case LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_NOTIFICATION_DROPPED:
 258                 /* No payload to consume. */
 259                 status = LTTNG_NOTIFICATION_CHANNEL_STATUS_NOTIFICATIONS_DROPPED;
 260                 break;
 261         default:
 262                 /* Protocol error. */
 263                 status = LTTNG_NOTIFICATION_CHANNEL_STATUS_ERROR;
 264                 goto end_unlock;
 265         }
 266
 267 end_unlock:
 268         pthread_mutex_unlock(&channel->lock);
 269 end:
 270         if (_notification) {
 271                 *_notification = notification;
 272         }
 273         return status;
 274 }
 275
 276 static
 277 int enqueue_dropped_notification(
 278                 struct lttng_notification_channel *channel)
 279 {
 280         int ret = 0;
 281         struct pending_notification *pending_notification;
 282         struct cds_list_head *last_element =
 283                         channel->pending_notifications.list.prev;
 284
 285         pending_notification = caa_container_of(last_element,
 286                         struct pending_notification, node);
 287         if (!pending_notification->notification) {
 288                 /*
 289                  * The last enqueued notification indicates dropped
 290                  * notifications; there is nothing to do as we group
 291                  * dropped notifications together.
 292                  */
 293                 goto end;
 294         }
 295
 296         if (channel->pending_notifications.count >=
 297                         DEFAULT_CLIENT_MAX_QUEUED_NOTIFICATIONS_COUNT &&
 298                         pending_notification->notification) {
 299                 /*
 300                  * Discard the last enqueued notification to indicate
 301                  * that notifications were dropped at this point.
 302                  */
 303                 lttng_notification_destroy(
 304                                 pending_notification->notification);
 305                 pending_notification->notification = NULL;
 306                 goto end;
 307         }
 308
 309         pending_notification = zmalloc(sizeof(*pending_notification));
 310         if (!pending_notification) {
 311                 ret = -1;
 312                 goto end;
 313         }
 314         CDS_INIT_LIST_HEAD(&pending_notification->node);
 315         cds_list_add(&pending_notification->node,
 316                         &channel->pending_notifications.list);
 317         channel->pending_notifications.count++;
 318 end:
 319         return ret;
 320 }
 321
 322 static
 323 int enqueue_notification_from_current_message(
 324                 struct lttng_notification_channel *channel)
 325 {
 326         int ret = 0;
 327         struct lttng_notification *notification;
 328         struct pending_notification *pending_notification;
 329
 330         if (channel->pending_notifications.count >=
 331                         DEFAULT_CLIENT_MAX_QUEUED_NOTIFICATIONS_COUNT) {
 332                 /* Drop the notification. */
 333                 ret = enqueue_dropped_notification(channel);
 334                 goto end;
 335         }
 336
 337         pending_notification = zmalloc(sizeof(*pending_notification));
 338         if (!pending_notification) {
 339                 ret = -1;
 340                 goto error;
 341         }
 342         CDS_INIT_LIST_HEAD(&pending_notification->node);
 343
 344         notification = create_notification_from_current_message(channel);
 345         if (!notification) {
 346                 ret = -1;
 347                 goto error;
 348         }
 349
 350         pending_notification->notification = notification;
 351         cds_list_add(&pending_notification->node,
 352                         &channel->pending_notifications.list);
 353         channel->pending_notifications.count++;
 354 end:
 355         return ret;
 356 error:
 357         free(pending_notification);
 358         goto end;
 359 }
 360
 361 enum lttng_notification_channel_status
 362 lttng_notification_channel_has_pending_notification(
 363                 struct lttng_notification_channel *channel,
 364                 bool *_notification_pending)
 365 {
 366         int ret;
 367         enum lttng_notification_channel_status status =
 368                         LTTNG_NOTIFICATION_CHANNEL_STATUS_OK;
 369         fd_set read_fds;
 370         struct timeval timeout;
 371
 372         FD_ZERO(&read_fds);
 373         memset(&timeout, 0, sizeof(timeout));
 374
 375         if (!channel || !_notification_pending) {
 376                 status = LTTNG_NOTIFICATION_CHANNEL_STATUS_INVALID;
 377                 goto end;
 378         }
 379
 380         pthread_mutex_lock(&channel->lock);
 381
 382         if (channel->pending_notifications.count) {
 383                 *_notification_pending = true;
 384                 goto end_unlock;
 385         }
 386
 387         if (channel->socket < 0) {
 388                 status = LTTNG_NOTIFICATION_CHANNEL_STATUS_CLOSED;
 389                 goto end_unlock;
 390         }
 391
 392         /*
 393          * Check, without blocking, if data is available on the channel's
 394          * socket. If there is data available, it is safe to read (blocking)
 395          * on the socket for a message from the session daemon.
 396          *
 397          * Since all commands wait for the session daemon's reply before
 398          * releasing the channel's lock, the protocol only allows for
 399          * notifications and "notification dropped" messages to come
 400          * through. If we receive a different message type, it is
 401          * considered a protocol error.
 402          *
 403          * Note that this function is not guaranteed not to block. This
 404          * will block until our peer (the session daemon) has sent a complete
 405          * message if we see data available on the socket. If the peer does
 406          * not respect the protocol, this may block indefinitely.
 407          */
 408         FD_SET(channel->socket, &read_fds);
 409         do {
 410                 ret = select(channel->socket + 1, &read_fds, NULL, NULL, &timeout);
 411         } while (ret < 0 && errno == EINTR);
 412
 413         if (ret == 0) {
 414                 /* No data available. */
 415                 *_notification_pending = false;
 416                 goto end_unlock;
 417         } else if (ret < 0) {
 418                 status = LTTNG_NOTIFICATION_CHANNEL_STATUS_ERROR;
 419                 goto end_unlock;
 420         }
 421
 422         /* Data available on socket. */
 423         ret = receive_message(channel);
 424         if (ret) {
 425                 status = LTTNG_NOTIFICATION_CHANNEL_STATUS_ERROR;
 426                 goto end_unlock;
 427         }
 428
 429         switch (get_current_message_type(channel)) {
 430         case LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_NOTIFICATION:
 431                 ret = enqueue_notification_from_current_message(channel);
 432                 if (ret) {
 433                         goto end_unlock;
 434                 }
 435                 *_notification_pending = true;
 436                 break;
 437         case LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_NOTIFICATION_DROPPED:
 438                 ret = enqueue_dropped_notification(channel);
 439                 if (ret) {
 440                         goto end_unlock;
 441                 }
 442                 *_notification_pending = true;
 443                 break;
 444         default:
 445                 /* Protocol error. */
 446                 status = LTTNG_NOTIFICATION_CHANNEL_STATUS_ERROR;
 447                 goto end_unlock;
 448         }
 449
 450 end_unlock:
 451         pthread_mutex_unlock(&channel->lock);
 452 end:
 453         return status;
 454 }
 455
 456 static
 457 int receive_command_reply(struct lttng_notification_channel *channel,
 458                 enum lttng_notification_channel_status *status)
 459 {
 460         int ret;
 461         struct lttng_notification_channel_command_reply *reply;
 462
 463         while (true) {
 464                 enum lttng_notification_channel_message_type msg_type;
 465
 466                 ret = receive_message(channel);
 467                 if (ret) {
 468                         goto end;
 469                 }
 470
 471                 msg_type = get_current_message_type(channel);
 472                 switch (msg_type) {
 473                 case LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_COMMAND_REPLY:
 474                         goto exit_loop;
 475                 case LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_NOTIFICATION:
 476                         ret = enqueue_notification_from_current_message(
 477                                         channel);
 478                         if (ret) {
 479                                 goto end;
 480                         }
 481                         break;
 482                 case LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_NOTIFICATION_DROPPED:
 483                         ret = enqueue_dropped_notification(channel);
 484                         if (ret) {
 485                                 goto end;
 486                         }
 487                         break;
 488                 case LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_HANDSHAKE:
 489                 {
 490                         struct lttng_notification_channel_command_handshake *handshake;
 491
 492                         handshake = (struct lttng_notification_channel_command_handshake *)
 493                                         (channel->reception_buffer.data +
 494                                         sizeof(struct lttng_notification_channel_message));
 495                         channel->version.major = handshake->major;
 496                         channel->version.minor = handshake->minor;
 497                         channel->version.set = true;
 498                         break;
 499                 }
 500                 default:
 501                         ret = -1;
 502                         goto end;
 503                 }
 504         }
 505
 506 exit_loop:
 507         if (channel->reception_buffer.size <
 508                         (sizeof(struct lttng_notification_channel_message) +
 509                         sizeof(*reply))) {
 510                 /* Invalid message received. */
 511                 ret = -1;
 512                 goto end;
 513         }
 514
 515         reply = (struct lttng_notification_channel_command_reply *)
 516                         (channel->reception_buffer.data +
 517                         sizeof(struct lttng_notification_channel_message));
 518         *status = (enum lttng_notification_channel_status) reply->status;
 519 end:
 520         return ret;
 521 }
 522
 523 static
 524 int handshake(struct lttng_notification_channel *channel)
 525 {
 526         ssize_t ret;
 527         enum lttng_notification_channel_status status =
 528                         LTTNG_NOTIFICATION_CHANNEL_STATUS_OK;
 529         struct lttng_notification_channel_command_handshake handshake = {
 530                 .major = LTTNG_NOTIFICATION_CHANNEL_VERSION_MAJOR,
 531                 .minor = LTTNG_NOTIFICATION_CHANNEL_VERSION_MINOR,
 532         };
 533         struct lttng_notification_channel_message msg_header = {
 534                 .type = LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_HANDSHAKE,
 535                 .size = sizeof(handshake),
 536         };
 537         char send_buffer[sizeof(msg_header) + sizeof(handshake)];
 538
 539         memcpy(send_buffer, &msg_header, sizeof(msg_header));
 540         memcpy(send_buffer + sizeof(msg_header), &handshake, sizeof(handshake));
 541
 542         pthread_mutex_lock(&channel->lock);
 543
 544         ret = lttcomm_send_creds_unix_sock(channel->socket, send_buffer,
 545                         sizeof(send_buffer));
 546         if (ret < 0) {
 547                 goto end_unlock;
 548         }
 549
 550         /* Receive handshake info from the sessiond. */
 551         ret = receive_command_reply(channel, &status);
 552         if (ret < 0) {
 553                 goto end_unlock;
 554         }
 555
 556         if (!channel->version.set) {
 557                 ret = -1;
 558                 goto end_unlock;
 559         }
 560
 561         if (channel->version.major != LTTNG_NOTIFICATION_CHANNEL_VERSION_MAJOR) {
 562                 ret = -1;
 563                 goto end_unlock;
 564         }
 565
 566 end_unlock:
 567         pthread_mutex_unlock(&channel->lock);
 568         return ret;
 569 }
 570
 571 static
 572 enum lttng_notification_channel_status send_condition_command(
 573                 struct lttng_notification_channel *channel,
 574                 enum lttng_notification_channel_message_type type,
 575                 const struct lttng_condition *condition)
 576 {
 577         int socket;
 578         ssize_t ret;
 579         enum lttng_notification_channel_status status =
 580                         LTTNG_NOTIFICATION_CHANNEL_STATUS_OK;
 581         struct lttng_dynamic_buffer buffer;
 582         struct lttng_notification_channel_message cmd_header = {
 583                 .type = (int8_t) type,
 584         };
 585
 586         lttng_dynamic_buffer_init(&buffer);
 587
 588         if (!channel) {
 589                 status = LTTNG_NOTIFICATION_CHANNEL_STATUS_INVALID;
 590                 goto end;
 591         }
 592
 593         assert(type == LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_SUBSCRIBE ||
 594                 type == LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_UNSUBSCRIBE);
 595
 596         pthread_mutex_lock(&channel->lock);
 597         socket = channel->socket;
 598         if (!lttng_condition_validate(condition)) {
 599                 status = LTTNG_NOTIFICATION_CHANNEL_STATUS_INVALID;
 600                 goto end_unlock;
 601         }
 602
 603         ret = lttng_dynamic_buffer_append(&buffer, &cmd_header,
 604                         sizeof(cmd_header));
 605         if (ret) {
 606                 status = LTTNG_NOTIFICATION_CHANNEL_STATUS_ERROR;
 607                 goto end_unlock;
 608         }
 609
 610         ret = lttng_condition_serialize(condition, &buffer);
 611         if (ret) {
 612                 status = LTTNG_NOTIFICATION_CHANNEL_STATUS_INVALID;
 613                 goto end_unlock;
 614         }
 615
 616         /* Update payload length. */
 617         ((struct lttng_notification_channel_message *) buffer.data)->size =
 618                         (uint32_t) (buffer.size - sizeof(cmd_header));
 619
 620         ret = lttcomm_send_unix_sock(socket, buffer.data, buffer.size);
 621         if (ret < 0) {
 622                 status = LTTNG_NOTIFICATION_CHANNEL_STATUS_ERROR;
 623                 goto end_unlock;
 624         }
 625
 626         ret = receive_command_reply(channel, &status);
 627         if (ret < 0) {
 628                 status = LTTNG_NOTIFICATION_CHANNEL_STATUS_ERROR;
 629                 goto end_unlock;
 630         }
 631 end_unlock:
 632         pthread_mutex_unlock(&channel->lock);
 633 end:
 634         lttng_dynamic_buffer_reset(&buffer);
 635         return status;
 636 }
 637
 638 enum lttng_notification_channel_status lttng_notification_channel_subscribe(
 639                 struct lttng_notification_channel *channel,
 640                 const struct lttng_condition *condition)
 641 {
 642         return send_condition_command(channel,
 643                         LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_SUBSCRIBE,
 644                         condition);
 645 }
 646
 647 enum lttng_notification_channel_status lttng_notification_channel_unsubscribe(
 648                 struct lttng_notification_channel *channel,
 649                 const struct lttng_condition *condition)
 650 {
 651         return send_condition_command(channel,
 652                         LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_UNSUBSCRIBE,
 653                         condition);
 654 }
 655
 656 void lttng_notification_channel_destroy(
 657                 struct lttng_notification_channel *channel)
 658 {
 659         if (!channel) {
 660                 return;
 661         }
 662
 663         if (channel->socket >= 0) {
 664                 (void) lttcomm_close_unix_sock(channel->socket);
 665         }
 666         pthread_mutex_destroy(&channel->lock);
 667         lttng_dynamic_buffer_reset(&channel->reception_buffer);
 668         free(channel);
 669 }