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
  30 static
  31 int handshake(struct lttng_notification_channel *channel);
  32
  33 /*
  34  * Populates the reception buffer with the next complete message.
  35  * The caller must acquire the client's lock.
  36  */
  37 static
  38 int receive_message(struct lttng_notification_channel *channel)
  39 {
  40         ssize_t ret;
  41         struct lttng_notification_channel_message msg;
  42
  43         ret = lttng_dynamic_buffer_set_size(&channel->reception_buffer, 0);
  44         if (ret) {
  45                 goto error;
  46         }
  47
  48         ret = lttcomm_recv_unix_sock(channel->socket, &msg, sizeof(msg));
  49         if (ret <= 0) {
  50                 ret = -1;
  51                 goto error;
  52         }
  53
  54         if (msg.size > DEFAULT_MAX_NOTIFICATION_CLIENT_MESSAGE_PAYLOAD_SIZE) {
  55                 ret = -1;
  56                 goto error;
  57         }
  58
  59         /* Add message header at buffer's start. */
  60         ret = lttng_dynamic_buffer_append(&channel->reception_buffer, &msg,
  61                         sizeof(msg));
  62         if (ret) {
  63                 goto error;
  64         }
  65
  66         /* Reserve space for the payload. */
  67         ret = lttng_dynamic_buffer_set_size(&channel->reception_buffer,
  68                         channel->reception_buffer.size + msg.size);
  69         if (ret) {
  70                 goto error;
  71         }
  72
  73         /* Receive message payload. */
  74         ret = lttcomm_recv_unix_sock(channel->socket,
  75                         channel->reception_buffer.data + sizeof(msg), msg.size);
  76         if (ret < (ssize_t) msg.size) {
  77                 ret = -1;
  78                 goto error;
  79         }
  80         ret = 0;
  81 end:
  82         return ret;
  83 error:
  84         if (lttng_dynamic_buffer_set_size(&channel->reception_buffer, 0)) {
  85                 ret = -1;
  86         }
  87         goto end;
  88 }
  89
  90 static
  91 enum lttng_notification_channel_message_type get_current_message_type(
  92                 struct lttng_notification_channel *channel)
  93 {
  94         struct lttng_notification_channel_message *msg;
  95
  96         assert(channel->reception_buffer.size >= sizeof(*msg));
  97
  98         msg = (struct lttng_notification_channel_message *)
  99                         channel->reception_buffer.data;
 100         return (enum lttng_notification_channel_message_type) msg->type;
 101 }
 102
 103 static
 104 struct lttng_notification *create_notification_from_current_message(
 105                 struct lttng_notification_channel *channel)
 106 {
 107         ssize_t ret;
 108         struct lttng_notification *notification = NULL;
 109         struct lttng_buffer_view view;
 110
 111         if (channel->reception_buffer.size <=
 112                         sizeof(struct lttng_notification_channel_message)) {
 113                 goto end;
 114         }
 115
 116         view = lttng_buffer_view_from_dynamic_buffer(&channel->reception_buffer,
 117                         sizeof(struct lttng_notification_channel_message), -1);
 118
 119         ret = lttng_notification_create_from_buffer(&view, &notification);
 120         if (ret != channel->reception_buffer.size -
 121                         sizeof(struct lttng_notification_channel_message)) {
 122                 lttng_notification_destroy(notification);
 123                 notification = NULL;
 124                 goto end;
 125         }
 126 end:
 127         return notification;
 128 }
 129
 130 struct lttng_notification_channel *lttng_notification_channel_create(
 131                 struct lttng_endpoint *endpoint)
 132 {
 133         int fd, ret;
 134         bool is_in_tracing_group = false, is_root = false;
 135         char *sock_path = NULL;
 136         struct lttng_notification_channel *channel = NULL;
 137
 138         if (!endpoint ||
 139                         endpoint != lttng_session_daemon_notification_endpoint) {
 140                 goto end;
 141         }
 142
 143         sock_path = zmalloc(LTTNG_PATH_MAX);
 144         if (!sock_path) {
 145                 goto end;
 146         }
 147
 148         channel = zmalloc(sizeof(struct lttng_notification_channel));
 149         if (!channel) {
 150                 goto end;
 151         }
 152         channel->socket = -1;
 153         pthread_mutex_init(&channel->lock, NULL);
 154         lttng_dynamic_buffer_init(&channel->reception_buffer);
 155         CDS_INIT_LIST_HEAD(&channel->pending_notifications.list);
 156
 157         is_root = (getuid() == 0);
 158         if (!is_root) {
 159                 is_in_tracing_group = lttng_check_tracing_group();
 160         }
 161
 162         if (is_root || is_in_tracing_group) {
 163                 lttng_ctl_copy_string(sock_path,
 164                                 DEFAULT_GLOBAL_NOTIFICATION_CHANNEL_UNIX_SOCK,
 165                                 LTTNG_PATH_MAX);
 166                 ret = lttcomm_connect_unix_sock(sock_path);
 167                 if (ret >= 0) {
 168                         fd = ret;
 169                         goto set_fd;
 170                 }
 171         }
 172
 173         /* Fallback to local session daemon. */
 174         ret = snprintf(sock_path, LTTNG_PATH_MAX,
 175                         DEFAULT_HOME_NOTIFICATION_CHANNEL_UNIX_SOCK,
 176                         utils_get_home_dir());
 177         if (ret < 0 || ret >= LTTNG_PATH_MAX) {
 178                 goto error;
 179         }
 180
 181         ret = lttcomm_connect_unix_sock(sock_path);
 182         if (ret < 0) {
 183                 goto error;
 184         }
 185         fd = ret;
 186
 187 set_fd:
 188         channel->socket = fd;
 189
 190         ret = handshake(channel);
 191         if (ret) {
 192                 goto error;
 193         }
 194 end:
 195         free(sock_path);
 196         return channel;
 197 error:
 198         lttng_notification_channel_destroy(channel);
 199         channel = NULL;
 200         goto end;
 201 }
 202
 203 enum lttng_notification_channel_status
 204 lttng_notification_channel_get_next_notification(
 205                 struct lttng_notification_channel *channel,
 206                 struct lttng_notification **_notification)
 207 {
 208         int ret;
 209         struct lttng_notification *notification = NULL;
 210         enum lttng_notification_channel_status status =
 211                         LTTNG_NOTIFICATION_CHANNEL_STATUS_OK;
 212
 213         if (!channel || !_notification) {
 214                 status = LTTNG_NOTIFICATION_CHANNEL_STATUS_INVALID;
 215                 goto end;
 216         }
 217
 218         pthread_mutex_lock(&channel->lock);
 219
 220         if (channel->pending_notifications.count) {
 221                 struct pending_notification *pending_notification;
 222
 223                 assert(!cds_list_empty(&channel->pending_notifications.list));
 224
 225                 /* Deliver one of the pending notifications. */
 226                 pending_notification = cds_list_first_entry(
 227                                 &channel->pending_notifications.list,
 228                                 struct pending_notification,
 229                                 node);
 230                 notification = pending_notification->notification;
 231                 if (!notification) {
 232                         status = LTTNG_NOTIFICATION_CHANNEL_STATUS_NOTIFICATIONS_DROPPED;
 233                 }
 234                 cds_list_del(&pending_notification->node);
 235                 channel->pending_notifications.count--;
 236                 free(pending_notification);
 237                 goto end_unlock;
 238         }
 239
 240         ret = receive_message(channel);
 241         if (ret) {
 242                 status = LTTNG_NOTIFICATION_CHANNEL_STATUS_ERROR;
 243                 goto end_unlock;
 244         }
 245
 246         switch (get_current_message_type(channel)) {
 247         case LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_NOTIFICATION:
 248                 notification = create_notification_from_current_message(
 249                                 channel);
 250                 if (!notification) {
 251                         status = LTTNG_NOTIFICATION_CHANNEL_STATUS_ERROR;
 252                         goto end_unlock;
 253                 }
 254                 break;
 255         case LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_NOTIFICATION_DROPPED:
 256                 /* No payload to consume. */
 257                 status = LTTNG_NOTIFICATION_CHANNEL_STATUS_NOTIFICATIONS_DROPPED;
 258                 break;
 259         default:
 260                 /* Protocol error. */
 261                 status = LTTNG_NOTIFICATION_CHANNEL_STATUS_ERROR;
 262                 goto end_unlock;
 263         }
 264
 265 end_unlock:
 266         pthread_mutex_unlock(&channel->lock);
 267         *_notification = notification;
 268 end:
 269         return status;
 270 }
 271
 272 static
 273 int enqueue_dropped_notification(
 274                 struct lttng_notification_channel *channel)
 275 {
 276         int ret = 0;
 277         struct pending_notification *pending_notification;
 278         struct cds_list_head *last_element =
 279                         channel->pending_notifications.list.prev;
 280
 281         pending_notification = caa_container_of(last_element,
 282                         struct pending_notification, node);
 283         if (!pending_notification->notification) {
 284                 /*
 285                  * The last enqueued notification indicates dropped
 286                  * notifications; there is nothing to do as we group
 287                  * dropped notifications together.
 288                  */
 289                 goto end;
 290         }
 291
 292         if (channel->pending_notifications.count >=
 293                         DEFAULT_CLIENT_MAX_QUEUED_NOTIFICATIONS_COUNT &&
 294                         pending_notification->notification) {
 295                 /*
 296                  * Discard the last enqueued notification to indicate
 297                  * that notifications were dropped at this point.
 298                  */
 299                 lttng_notification_destroy(
 300                                 pending_notification->notification);
 301                 pending_notification->notification = NULL;
 302                 goto end;
 303         }
 304
 305         pending_notification = zmalloc(sizeof(*pending_notification));
 306         if (!pending_notification) {
 307                 ret = -1;
 308                 goto end;
 309         }
 310         CDS_INIT_LIST_HEAD(&pending_notification->node);
 311         cds_list_add(&pending_notification->node,
 312                         &channel->pending_notifications.list);
 313         channel->pending_notifications.count++;
 314 end:
 315         return ret;
 316 }
 317
 318 static
 319 int enqueue_notification_from_current_message(
 320                 struct lttng_notification_channel *channel)
 321 {
 322         int ret = 0;
 323         struct lttng_notification *notification;
 324         struct pending_notification *pending_notification;
 325
 326         if (channel->pending_notifications.count >=
 327                         DEFAULT_CLIENT_MAX_QUEUED_NOTIFICATIONS_COUNT) {
 328                 /* Drop the notification. */
 329                 ret = enqueue_dropped_notification(channel);
 330                 goto end;
 331         }
 332
 333         pending_notification = zmalloc(sizeof(*pending_notification));
 334         if (!pending_notification) {
 335                 ret = -1;
 336                 goto error;
 337         }
 338         CDS_INIT_LIST_HEAD(&pending_notification->node);
 339
 340         notification = create_notification_from_current_message(channel);
 341         if (!notification) {
 342                 ret = -1;
 343                 goto error;
 344         }
 345
 346         pending_notification->notification = notification;
 347         cds_list_add(&pending_notification->node,
 348                         &channel->pending_notifications.list);
 349         channel->pending_notifications.count++;
 350 end:
 351         return ret;
 352 error:
 353         free(pending_notification);
 354         goto end;
 355 }
 356
 357 static
 358 int receive_command_reply(struct lttng_notification_channel *channel,
 359                 enum lttng_notification_channel_status *status)
 360 {
 361         int ret;
 362         struct lttng_notification_channel_command_reply *reply;
 363
 364         while (true) {
 365                 enum lttng_notification_channel_message_type msg_type;
 366
 367                 ret = receive_message(channel);
 368                 if (ret) {
 369                         goto end;
 370                 }
 371
 372                 msg_type = get_current_message_type(channel);
 373                 switch (msg_type) {
 374                 case LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_COMMAND_REPLY:
 375                         goto exit_loop;
 376                 case LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_NOTIFICATION:
 377                         ret = enqueue_notification_from_current_message(
 378                                         channel);
 379                         if (ret) {
 380                                 goto end;
 381                         }
 382                         break;
 383                 case LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_NOTIFICATION_DROPPED:
 384                         ret = enqueue_dropped_notification(channel);
 385                         if (ret) {
 386                                 goto end;
 387                         }
 388                         break;
 389                 case LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_HANDSHAKE:
 390                 {
 391                         struct lttng_notification_channel_command_handshake *handshake;
 392
 393                         handshake = (struct lttng_notification_channel_command_handshake *)
 394                                         (channel->reception_buffer.data +
 395                                         sizeof(struct lttng_notification_channel_message));
 396                         channel->version.major = handshake->major;
 397                         channel->version.minor = handshake->minor;
 398                         channel->version.set = true;
 399                         break;
 400                 }
 401                 default:
 402                         ret = -1;
 403                         goto end;
 404                 }
 405         }
 406
 407 exit_loop:
 408         if (channel->reception_buffer.size <
 409                         (sizeof(struct lttng_notification_channel_message) +
 410                         sizeof(*reply))) {
 411                 /* Invalid message received. */
 412                 ret = -1;
 413                 goto end;
 414         }
 415
 416         reply = (struct lttng_notification_channel_command_reply *)
 417                         (channel->reception_buffer.data +
 418                         sizeof(struct lttng_notification_channel_message));
 419         *status = (enum lttng_notification_channel_status) reply->status;
 420 end:
 421         return ret;
 422 }
 423
 424 static
 425 int handshake(struct lttng_notification_channel *channel)
 426 {
 427         ssize_t ret;
 428         enum lttng_notification_channel_status status =
 429                         LTTNG_NOTIFICATION_CHANNEL_STATUS_OK;
 430         struct lttng_notification_channel_command_handshake handshake = {
 431                 .major = LTTNG_NOTIFICATION_CHANNEL_VERSION_MAJOR,
 432                 .minor = LTTNG_NOTIFICATION_CHANNEL_VERSION_MINOR,
 433         };
 434         struct lttng_notification_channel_message msg_header = {
 435                 .type = LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_HANDSHAKE,
 436                 .size = sizeof(handshake),
 437         };
 438         char send_buffer[sizeof(msg_header) + sizeof(handshake)];
 439
 440         memcpy(send_buffer, &msg_header, sizeof(msg_header));
 441         memcpy(send_buffer + sizeof(msg_header), &handshake, sizeof(handshake));
 442
 443         pthread_mutex_lock(&channel->lock);
 444
 445         ret = lttcomm_send_creds_unix_sock(channel->socket, send_buffer,
 446                         sizeof(send_buffer));
 447         if (ret < 0) {
 448                 goto end_unlock;
 449         }
 450
 451         /* Receive handshake info from the sessiond. */
 452         ret = receive_command_reply(channel, &status);
 453         if (ret < 0) {
 454                 goto end_unlock;
 455         }
 456
 457         if (!channel->version.set) {
 458                 ret = -1;
 459                 goto end_unlock;
 460         }
 461
 462         if (channel->version.major != LTTNG_NOTIFICATION_CHANNEL_VERSION_MAJOR) {
 463                 ret = -1;
 464                 goto end_unlock;
 465         }
 466
 467 end_unlock:
 468         pthread_mutex_unlock(&channel->lock);
 469         return ret;
 470 }
 471
 472 static
 473 enum lttng_notification_channel_status send_condition_command(
 474                 struct lttng_notification_channel *channel,
 475                 enum lttng_notification_channel_message_type type,
 476                 const struct lttng_condition *condition)
 477 {
 478         int socket;
 479         ssize_t command_size, ret;
 480         enum lttng_notification_channel_status status =
 481                         LTTNG_NOTIFICATION_CHANNEL_STATUS_OK;
 482         char *command_buffer = NULL;
 483         struct lttng_notification_channel_message cmd_message = {
 484                 .type = type,
 485         };
 486
 487         if (!channel) {
 488                 status = LTTNG_NOTIFICATION_CHANNEL_STATUS_INVALID;
 489                 goto end;
 490         }
 491
 492         assert(type == LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_SUBSCRIBE ||
 493                 type == LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_UNSUBSCRIBE);
 494
 495         pthread_mutex_lock(&channel->lock);
 496         socket = channel->socket;
 497         if (!lttng_condition_validate(condition)) {
 498                 status = LTTNG_NOTIFICATION_CHANNEL_STATUS_INVALID;
 499                 goto end_unlock;
 500         }
 501
 502         ret = lttng_condition_serialize(condition, NULL);
 503         if (ret < 0) {
 504                 status = LTTNG_NOTIFICATION_CHANNEL_STATUS_INVALID;
 505                 goto end_unlock;
 506         }
 507         assert(ret < UINT32_MAX);
 508         cmd_message.size = (uint32_t) ret;
 509         command_size = ret + sizeof(
 510                         struct lttng_notification_channel_message);
 511         command_buffer = zmalloc(command_size);
 512         if (!command_buffer) {
 513                 goto end_unlock;
 514         }
 515
 516         memcpy(command_buffer, &cmd_message, sizeof(cmd_message));
 517         ret = lttng_condition_serialize(condition,
 518                         command_buffer + sizeof(cmd_message));
 519         if (ret < 0) {
 520                 goto end_unlock;
 521         }
 522
 523         ret = lttcomm_send_unix_sock(socket, command_buffer, command_size);
 524         if (ret < 0) {
 525                 status = LTTNG_NOTIFICATION_CHANNEL_STATUS_ERROR;
 526                 goto end_unlock;
 527         }
 528
 529         ret = receive_command_reply(channel, &status);
 530         if (ret < 0) {
 531                 status = LTTNG_NOTIFICATION_CHANNEL_STATUS_ERROR;
 532                 goto end_unlock;
 533         }
 534 end_unlock:
 535         pthread_mutex_unlock(&channel->lock);
 536 end:
 537         free(command_buffer);
 538         return status;
 539 }
 540
 541 enum lttng_notification_channel_status lttng_notification_channel_subscribe(
 542                 struct lttng_notification_channel *channel,
 543                 const struct lttng_condition *condition)
 544 {
 545         return send_condition_command(channel,
 546                         LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_SUBSCRIBE,
 547                         condition);
 548 }
 549
 550 enum lttng_notification_channel_status lttng_notification_channel_unsubscribe(
 551                 struct lttng_notification_channel *channel,
 552                 const struct lttng_condition *condition)
 553 {
 554         return send_condition_command(channel,
 555                         LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_UNSUBSCRIBE,
 556                         condition);
 557 }
 558
 559 void lttng_notification_channel_destroy(
 560                 struct lttng_notification_channel *channel)
 561 {
 562         if (!channel) {
 563                 return;
 564         }
 565
 566         if (channel->socket >= 0) {
 567                 (void) lttcomm_close_unix_sock(channel->socket);
 568         }
 569         pthread_mutex_destroy(&channel->lock);
 570         lttng_dynamic_buffer_reset(&channel->reception_buffer);
 571         free(channel);
 572 }