liblttng-ust-comm/lttng-ust-comm.c

   1 /*
   2  * Copyright (C)  2011 - David Goulet <david.goulet@polymtl.ca>
   3  * Copyright (C)  2011 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   4  *
   5  * This library is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU Lesser General Public
   7  * License as published by the Free Software Foundation; only
   8  * version 2.1 of the License.
   9  *
  10  * This library is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  13  * Lesser General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU Lesser General Public
  16  * License along with this library; if not, write to the Free Software
  17  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  18  */
  19
  20 #define _GNU_SOURCE
  21 #include <limits.h>
  22 #include <stdio.h>
  23 #include <stdlib.h>
  24 #include <string.h>
  25 #include <sys/socket.h>
  26 #include <sys/stat.h>
  27 #include <sys/types.h>
  28 #include <sys/un.h>
  29 #include <unistd.h>
  30 #include <assert.h>
  31 #include <errno.h>
  32 #include <fcntl.h>
  33
  34 #include <ust-comm.h>
  35
  36 /*
  37  * Human readable error message.
  38  */
  39 static const char *ustcomm_readable_code[] = {
  40         [ USTCOMM_ERR_INDEX(USTCOMM_ERR) ] = "Unknown error",
  41         [ USTCOMM_ERR_INDEX(USTCOMM_UND) ] = "Undefined command",
  42         [ USTCOMM_ERR_INDEX(USTCOMM_NOT_IMPLEMENTED) ] = "Not implemented",
  43         [ USTCOMM_ERR_INDEX(USTCOMM_UNKNOWN_DOMAIN) ] = "Unknown tracing domain",
  44         [ USTCOMM_ERR_INDEX(USTCOMM_NO_SESSION) ] = "No session found",
  45         [ USTCOMM_ERR_INDEX(USTCOMM_LIST_FAIL) ] = "Unable to list traceable apps",
  46         [ USTCOMM_ERR_INDEX(USTCOMM_NO_APPS) ] = "No traceable apps found",
  47         [ USTCOMM_ERR_INDEX(USTCOMM_SESS_NOT_FOUND) ] = "Session name not found",
  48         [ USTCOMM_ERR_INDEX(USTCOMM_NO_TRACE) ] = "No trace found",
  49         [ USTCOMM_ERR_INDEX(USTCOMM_FATAL) ] = "Fatal error of the session daemon",
  50         [ USTCOMM_ERR_INDEX(USTCOMM_CREATE_FAIL) ] = "Create trace failed",
  51         [ USTCOMM_ERR_INDEX(USTCOMM_START_FAIL) ] = "Start trace failed",
  52         [ USTCOMM_ERR_INDEX(USTCOMM_STOP_FAIL) ] = "Stop trace failed",
  53         [ USTCOMM_ERR_INDEX(USTCOMM_NO_TRACEABLE) ] = "App is not traceable",
  54         [ USTCOMM_ERR_INDEX(USTCOMM_SELECT_SESS) ] = "A session MUST be selected",
  55         [ USTCOMM_ERR_INDEX(USTCOMM_EXIST_SESS) ] = "Session name already exist",
  56         [ USTCOMM_ERR_INDEX(USTCOMM_KERN_NA) ] = "UST tracer not available",
  57         [ USTCOMM_ERR_INDEX(USTCOMM_KERN_EVENT_EXIST) ] = "UST event already exists",
  58         [ USTCOMM_ERR_INDEX(USTCOMM_KERN_SESS_FAIL) ] = "UST create session failed",
  59         [ USTCOMM_ERR_INDEX(USTCOMM_KERN_CHAN_FAIL) ] = "UST create channel failed",
  60         [ USTCOMM_ERR_INDEX(USTCOMM_KERN_CHAN_NOT_FOUND) ] = "UST channel not found",
  61         [ USTCOMM_ERR_INDEX(USTCOMM_KERN_CHAN_DISABLE_FAIL) ] = "Disable UST channel failed",
  62         [ USTCOMM_ERR_INDEX(USTCOMM_KERN_CHAN_ENABLE_FAIL) ] = "Enable UST channel failed",
  63         [ USTCOMM_ERR_INDEX(USTCOMM_KERN_CONTEXT_FAIL) ] = "Add UST context failed",
  64         [ USTCOMM_ERR_INDEX(USTCOMM_KERN_ENABLE_FAIL) ] = "Enable UST event failed",
  65         [ USTCOMM_ERR_INDEX(USTCOMM_KERN_DISABLE_FAIL) ] = "Disable UST event failed",
  66         [ USTCOMM_ERR_INDEX(USTCOMM_KERN_META_FAIL) ] = "Opening metadata failed",
  67         [ USTCOMM_ERR_INDEX(USTCOMM_KERN_START_FAIL) ] = "Starting UST trace failed",
  68         [ USTCOMM_ERR_INDEX(USTCOMM_KERN_STOP_FAIL) ] = "Stoping UST trace failed",
  69         [ USTCOMM_ERR_INDEX(USTCOMM_KERN_CONSUMER_FAIL) ] = "UST consumer start failed",
  70         [ USTCOMM_ERR_INDEX(USTCOMM_KERN_STREAM_FAIL) ] = "UST create stream failed",
  71         [ USTCOMM_ERR_INDEX(USTCOMM_KERN_DIR_FAIL) ] = "UST trace directory creation failed",
  72         [ USTCOMM_ERR_INDEX(USTCOMM_KERN_DIR_EXIST) ] = "UST trace directory already exist",
  73         [ USTCOMM_ERR_INDEX(USTCOMM_KERN_NO_SESSION) ] = "No UST session found",
  74         [ USTCOMM_ERR_INDEX(USTCOMM_KERN_LIST_FAIL) ] = "Listing UST events failed",
  75         [ USTCOMM_ERR_INDEX(USTCONSUMER_COMMAND_SOCK_READY) ] = "UST consumer command socket ready",
  76         [ USTCOMM_ERR_INDEX(USTCONSUMER_SUCCESS_RECV_FD) ] = "UST consumer success on receiving fds",
  77         [ USTCOMM_ERR_INDEX(USTCONSUMER_ERROR_RECV_FD) ] = "UST consumer error on receiving fds",
  78         [ USTCOMM_ERR_INDEX(USTCONSUMER_POLL_ERROR) ] = "UST consumer error in polling thread",
  79         [ USTCOMM_ERR_INDEX(USTCONSUMER_POLL_NVAL) ] = "UST consumer polling on closed fd",
  80         [ USTCOMM_ERR_INDEX(USTCONSUMER_POLL_HUP) ] = "UST consumer all fd hung up",
  81         [ USTCOMM_ERR_INDEX(USTCONSUMER_EXIT_SUCCESS) ] = "UST consumer exiting normally",
  82         [ USTCOMM_ERR_INDEX(USTCONSUMER_EXIT_FAILURE) ] = "UST consumer exiting on error",
  83         [ USTCOMM_ERR_INDEX(USTCONSUMER_OUTFD_ERROR) ] = "UST consumer error opening the tracefile",
  84         [ USTCOMM_ERR_INDEX(USTCONSUMER_SPLICE_EBADF) ] = "UST consumer splice EBADF",
  85         [ USTCOMM_ERR_INDEX(USTCONSUMER_SPLICE_EINVAL) ] = "UST consumer splice EINVAL",
  86         [ USTCOMM_ERR_INDEX(USTCONSUMER_SPLICE_ENOMEM) ] = "UST consumer splice ENOMEM",
  87         [ USTCOMM_ERR_INDEX(USTCONSUMER_SPLICE_ESPIPE) ] = "UST consumer splice ESPIPE",
  88         [ USTCOMM_ERR_INDEX(USTCOMM_NO_EVENT) ] = "Event not found",
  89 };
  90
  91 /*
  92  *  lttcom_get_readable_code
  93  *
  94  *  Return ptr to string representing a human readable
  95  *  error code from the ustcomm_return_code enum.
  96  */
  97 const char *ustcomm_get_readable_code(int code)
  98 {
  99         if (code == USTCOMM_OK) {
 100                 return "Success";
 101         }
 102         if (code >= USTCOMM_ERR && code < USTCOMM_NR) {
 103                 return ustcomm_readable_code[USTCOMM_ERR_INDEX(code)];
 104         }
 105         return strerror(code);
 106 }
 107
 108 /*
 109  *      ustcomm_connect_unix_sock
 110  *
 111  *      Connect to unix socket using the path name.
 112  */
 113 int ustcomm_connect_unix_sock(const char *pathname)
 114 {
 115         struct sockaddr_un sun;
 116         int fd;
 117         int ret;
 118
 119         /*
 120          * libust threads require the close-on-exec flag for all
 121          * resources so it does not leak file descriptors upon exec.
 122          */
 123         fd = socket(PF_UNIX, SOCK_STREAM, 0);
 124         if (fd < 0) {
 125                 perror("socket");
 126                 ret = fd;
 127                 goto error;
 128         }
 129         ret = fcntl(fd, F_SETFD, FD_CLOEXEC);
 130         if (ret < 0) {
 131                 perror("fcntl");
 132                 goto error_fcntl;
 133         }
 134
 135         memset(&sun, 0, sizeof(sun));
 136         sun.sun_family = AF_UNIX;
 137         strncpy(sun.sun_path, pathname, sizeof(sun.sun_path));
 138         sun.sun_path[sizeof(sun.sun_path) - 1] = '\0';
 139
 140         ret = connect(fd, (struct sockaddr *) &sun, sizeof(sun));
 141         if (ret < 0) {
 142                 /*
 143                  * Don't print message on connect error, because connect
 144                  * is used in normal execution to detect if sessiond is
 145                  * alive.
 146                  */
 147                 goto error_connect;
 148         }
 149
 150         return fd;
 151
 152 error_connect:
 153 error_fcntl:
 154         close(fd);
 155 error:
 156         return ret;
 157 }
 158
 159 /*
 160  *      ustcomm_accept_unix_sock
 161  *
 162  *      Do an accept(2) on the sock and return the
 163  *      new file descriptor. The socket MUST be bind(2) before.
 164  */
 165 int ustcomm_accept_unix_sock(int sock)
 166 {
 167         int new_fd;
 168         struct sockaddr_un sun;
 169         socklen_t len = 0;
 170
 171         /* Blocking call */
 172         new_fd = accept(sock, (struct sockaddr *) &sun, &len);
 173         if (new_fd < 0) {
 174                 perror("accept");
 175                 return -1;
 176         }
 177         return new_fd;
 178 }
 179
 180 /*
 181  *      ustcomm_create_unix_sock
 182  *
 183  *      Creates a AF_UNIX local socket using pathname
 184  *      bind the socket upon creation and return the fd.
 185  */
 186 int ustcomm_create_unix_sock(const char *pathname)
 187 {
 188         struct sockaddr_un sun;
 189         int fd;
 190         int ret = -1;
 191
 192         /* Create server socket */
 193         if ((fd = socket(PF_UNIX, SOCK_STREAM, 0)) < 0) {
 194                 perror("socket");
 195                 goto error;
 196         }
 197
 198         memset(&sun, 0, sizeof(sun));
 199         sun.sun_family = AF_UNIX;
 200         strncpy(sun.sun_path, pathname, sizeof(sun.sun_path));
 201         sun.sun_path[sizeof(sun.sun_path) - 1] = '\0';
 202
 203         /* Unlink the old file if present */
 204         (void) unlink(pathname);
 205         ret = bind(fd, (struct sockaddr *) &sun, sizeof(sun));
 206         if (ret < 0) {
 207                 perror("bind");
 208                 goto error;
 209         }
 210
 211         return fd;
 212
 213 error:
 214         return ret;
 215 }
 216
 217 /*
 218  *      ustcomm_listen_unix_sock
 219  *
 220  *      Make the socket listen using LTTNG_UST_COMM_MAX_LISTEN.
 221  */
 222 int ustcomm_listen_unix_sock(int sock)
 223 {
 224         int ret;
 225
 226         ret = listen(sock, LTTNG_UST_COMM_MAX_LISTEN);
 227         if (ret < 0) {
 228                 perror("listen");
 229         }
 230
 231         return ret;
 232 }
 233
 234 /*
 235  *      ustcomm_recv_unix_sock
 236  *
 237  *  Receive data of size len in put that data into
 238  *  the buf param. Using recvmsg API.
 239  *  Return the size of received data.
 240  */
 241 ssize_t ustcomm_recv_unix_sock(int sock, void *buf, size_t len)
 242 {
 243         struct msghdr msg;
 244         struct iovec iov[1];
 245         ssize_t ret = -1;
 246
 247         memset(&msg, 0, sizeof(msg));
 248
 249         iov[0].iov_base = buf;
 250         iov[0].iov_len = len;
 251         msg.msg_iov = iov;
 252         msg.msg_iovlen = 1;
 253
 254         do {
 255                 ret = recvmsg(sock, &msg, 0);
 256         } while (ret < 0 && errno == EINTR);
 257         if (ret < 0 && errno != EPIPE) {
 258                 perror("recvmsg");
 259         }
 260
 261         return ret;
 262 }
 263
 264 /*
 265  *      ustcomm_send_unix_sock
 266  *
 267  *      Send buf data of size len. Using sendmsg API.
 268  *      Return the size of sent data.
 269  */
 270 ssize_t ustcomm_send_unix_sock(int sock, void *buf, size_t len)
 271 {
 272         struct msghdr msg;
 273         struct iovec iov[1];
 274         ssize_t ret = -1;
 275
 276         memset(&msg, 0, sizeof(msg));
 277
 278         iov[0].iov_base = buf;
 279         iov[0].iov_len = len;
 280         msg.msg_iov = iov;
 281         msg.msg_iovlen = 1;
 282
 283         /*
 284          * Using the MSG_NOSIGNAL when sending data from sessiond to
 285          * libust, so libust does not receive an unhandled SIGPIPE or
 286          * SIGURG. The sessiond receiver side can be made more resilient
 287          * by ignoring SIGPIPE, but we don't have this luxury on the
 288          * libust side.
 289          */
 290         do {
 291                 ret = sendmsg(sock, &msg, MSG_NOSIGNAL);
 292         } while (ret < 0 && errno == EINTR);
 293         if (ret < 0 && errno != EPIPE) {
 294                 perror("sendmsg");
 295         }
 296
 297         return ret;
 298 }
 299
 300 /*
 301  *  ustcomm_close_unix_sock
 302  *
 303  *  Shutdown cleanly a unix socket.
 304  */
 305 int ustcomm_close_unix_sock(int sock)
 306 {
 307         int ret;
 308
 309         ret = close(sock);
 310         if (ret < 0) {
 311                 perror("close");
 312         }
 313
 314         return ret;
 315 }
 316
 317 /*
 318  *  ustcomm_send_fds_unix_sock
 319  *
 320  *  Send multiple fds on a unix socket.
 321  */
 322 ssize_t ustcomm_send_fds_unix_sock(int sock, void *buf, int *fds, size_t nb_fd, size_t len)
 323 {
 324         struct msghdr msg;
 325         struct cmsghdr *cmptr;
 326         struct iovec iov[1];
 327         ssize_t ret = -1;
 328         unsigned int sizeof_fds = nb_fd * sizeof(int);
 329         char tmp[CMSG_SPACE(sizeof_fds)];
 330
 331         memset(&msg, 0, sizeof(msg));
 332
 333         /*
 334          * Note: the consumerd receiver only supports receiving one FD per
 335          * message.
 336          */
 337         assert(nb_fd == 1);
 338
 339         msg.msg_control = (caddr_t)tmp;
 340         msg.msg_controllen = CMSG_LEN(sizeof_fds);
 341
 342         cmptr = CMSG_FIRSTHDR(&msg);
 343         cmptr->cmsg_level = SOL_SOCKET;
 344         cmptr->cmsg_type = SCM_RIGHTS;
 345         cmptr->cmsg_len = CMSG_LEN(sizeof_fds);
 346         memcpy(CMSG_DATA(cmptr), fds, sizeof_fds);
 347         /* Sum of the length of all control messages in the buffer: */
 348         msg.msg_controllen = cmptr->cmsg_len;
 349
 350         iov[0].iov_base = buf;
 351         iov[0].iov_len = len;
 352         msg.msg_iov = iov;
 353         msg.msg_iovlen = 1;
 354
 355         do {
 356                 ret = sendmsg(sock, &msg, MSG_NOSIGNAL);
 357         } while (ret < 0 && errno == EINTR);
 358         if (ret < 0 && errno != EPIPE) {
 359                 perror("sendmsg");
 360         }
 361
 362         return ret;
 363 }
 364
 365 int ustcomm_send_app_msg(int sock, struct ustcomm_ust_msg *lum)
 366 {
 367         ssize_t len;
 368
 369         len = ustcomm_send_unix_sock(sock, lum, sizeof(*lum));
 370         switch (len) {
 371         case sizeof(*lum):
 372                 break;
 373         case -1:
 374                 if (errno == ECONNRESET) {
 375                         fprintf(stderr, "remote end closed connection\n");
 376                         return 0;
 377                 }
 378                 return -1;
 379         default:
 380                 fprintf(stderr, "incorrect message size: %zd\n", len);
 381                 return -1;
 382         }
 383         return 0;
 384 }
 385
 386 int ustcomm_recv_app_reply(int sock, struct ustcomm_ust_reply *lur,
 387                           uint32_t expected_handle, uint32_t expected_cmd)
 388 {
 389         ssize_t len;
 390
 391         memset(lur, 0, sizeof(*lur));
 392         len = ustcomm_recv_unix_sock(sock, lur, sizeof(*lur));
 393         switch (len) {
 394         case 0: /* orderly shutdown */
 395                 return -EINVAL;
 396         case sizeof(*lur):
 397                 if (lur->handle != expected_handle) {
 398                         fprintf(stderr, "Unexpected result message handle\n");
 399                         return -EINVAL;
 400                 }
 401
 402                 if (lur->cmd != expected_cmd) {
 403                         fprintf(stderr, "Unexpected result message command\n");
 404                         return -EINVAL;
 405                 }
 406                 if (lur->ret_code != USTCOMM_OK) {
 407                         /*
 408                          * Some errors are normal.. we should put this
 409                          * in a debug level message...
 410                          * fprintf(stderr, "remote operation failed with code %d.\n",
 411                          *      lur->ret_code);
 412                          */
 413                         return lur->ret_code;
 414                 }
 415                 return 0;
 416         case -1:
 417                 if (errno == ECONNRESET) {
 418                         fprintf(stderr, "remote end closed connection\n");
 419                         return -EINVAL;
 420                 }
 421                 return -1;
 422         default:
 423                 fprintf(stderr, "incorrect message size: %zd\n", len);
 424                 return len > 0 ? -1 : len;
 425         }
 426 }
 427
 428 int ustcomm_send_app_cmd(int sock,
 429                         struct ustcomm_ust_msg *lum,
 430                         struct ustcomm_ust_reply *lur)
 431 {
 432         int ret;
 433
 434         ret = ustcomm_send_app_msg(sock, lum);
 435         if (ret)
 436                 return ret;
 437         ret = ustcomm_recv_app_reply(sock, lur, lum->handle, lum->cmd);
 438         if (ret)
 439                 return ret;
 440         return 0;
 441 }
 442
 443
 444 /*
 445  * Receives a single fd from socket.
 446  *
 447  * Returns the size of received data
 448  */
 449 int ustcomm_recv_fd(int sock)
 450 {
 451         struct iovec iov[1];
 452         int ret = 0;
 453         int data_fd;
 454         struct cmsghdr *cmsg;
 455         char recv_fd[CMSG_SPACE(sizeof(int))];
 456         struct msghdr msg;
 457         union {
 458                 unsigned char vc[4];
 459                 int vi;
 460         } tmp;
 461         int i;
 462
 463         memset(&msg, 0, sizeof(msg));
 464
 465         /* Prepare to receive the structures */
 466         iov[0].iov_base = &data_fd;
 467         iov[0].iov_len = sizeof(data_fd);
 468         msg.msg_iov = iov;
 469         msg.msg_iovlen = 1;
 470         msg.msg_control = recv_fd;
 471         msg.msg_controllen = sizeof(recv_fd);
 472
 473         do {
 474                 ret = recvmsg(sock, &msg, 0);
 475         } while (ret < 0 && errno == EINTR);
 476         if (ret < 0) {
 477                 if (errno != EPIPE) {
 478                         perror("recvmsg");
 479                 }
 480                 goto end;
 481         }
 482         if (ret != sizeof(data_fd)) {
 483                 fprintf(stderr, "Received %d bytes, expected %zd", ret, sizeof(data_fd));
 484                 goto end;
 485         }
 486         cmsg = CMSG_FIRSTHDR(&msg);
 487         if (!cmsg) {
 488                 fprintf(stderr, "Invalid control message header\n");
 489                 ret = -1;
 490                 goto end;
 491         }
 492         if (cmsg->cmsg_level != SOL_SOCKET || cmsg->cmsg_type != SCM_RIGHTS) {
 493                 fprintf(stderr, "Didn't received any fd\n");
 494                 ret = -1;
 495                 goto end;
 496         }
 497         /* this is our fd */
 498         for (i = 0; i < sizeof(int); i++)
 499                 tmp.vc[i] = CMSG_DATA(cmsg)[i];
 500         ret = tmp.vi;
 501         /*
 502          * Useful for fd leak debug.
 503          * fprintf(stderr, "received fd %d\n", ret);
 504          */
 505 end:
 506         return ret;
 507 }