libustcomm/ustcomm.c

   1 /* Copyright (C) 2009  Pierre-Marc Fournier
   2  *
   3  * This library is free software; you can redistribute it and/or
   4  * modify it under the terms of the GNU Lesser General Public
   5  * License as published by the Free Software Foundation; either
   6  * version 2.1 of the License, or (at your option) any later version.
   7  *
   8  * This library is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * Lesser General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU Lesser General Public
  14  * License along with this library; if not, write to the Free Software
  15  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301 USA
  16  */
  17
  18 #define _GNU_SOURCE
  19 #include <sys/types.h>
  20 #include <signal.h>
  21 #include <errno.h>
  22 #include <sys/socket.h>
  23 #include <sys/un.h>
  24 #include <unistd.h>
  25 #include <poll.h>
  26 #include <sys/stat.h>
  27
  28 #include <stdio.h>
  29 #include <stdlib.h>
  30 #include <string.h>
  31 #include <execinfo.h>
  32
  33 #include "ustcomm.h"
  34 #include "usterr.h"
  35
  36 #define UNIX_PATH_MAX 108
  37
  38 #define MSG_MAX 1000
  39
  40 /* FIXME: ustcomm blocks on message sending, which might be problematic in
  41  * some cases. Fix the poll() usage so sends are buffered until they don't
  42  * block.
  43  */
  44
  45 //static void bt(void)
  46 //{
  47 //      void *buffer[100];
  48 //      int result;
  49 //
  50 //      result = backtrace(&buffer, 100);
  51 //      backtrace_symbols_fd(buffer, result, STDERR_FILENO);
  52 //}
  53
  54 char *strdup_malloc(const char *s)
  55 {
  56         char *retval;
  57
  58         if(s == NULL)
  59                 return NULL;
  60
  61         retval = (char *) malloc(strlen(s)+1);
  62
  63         strcpy(retval, s);
  64
  65         return retval;
  66 }
  67
  68 static int signal_process(pid_t pid)
  69 {
  70         return 0;
  71 }
  72
  73 int pid_is_online(pid_t pid) {
  74         return 1;
  75 }
  76
  77 static int send_message_fd(int fd, const char *msg)
  78 {
  79         int result;
  80
  81         result = send(fd, msg, strlen(msg), MSG_NOSIGNAL);
  82         if(result == -1) {
  83                 PERROR("send");
  84                 return -1;
  85         }
  86         else if(result == 0) {
  87                 return 0;
  88         }
  89
  90         return 1;
  91 }
  92
  93 /* Called by an app to ask the consumer daemon to connect to it. */
  94
  95 int ustcomm_request_consumer(pid_t pid, const char *channel)
  96 {
  97         char path[UNIX_PATH_MAX];
  98         int result;
  99         char *msg=NULL;
 100         int retval = 0;
 101         struct ustcomm_connection conn;
 102         char *explicit_daemon_socket_path;
 103
 104         explicit_daemon_socket_path = getenv("UST_DAEMON_SOCKET");
 105         if(explicit_daemon_socket_path) {
 106                 /* user specified explicitly a socket path */
 107                 result = snprintf(path, UNIX_PATH_MAX, "%s", explicit_daemon_socket_path);
 108         }
 109         else {
 110                 /* just use the default path */
 111                 result = snprintf(path, UNIX_PATH_MAX, "%s/ustd", SOCK_DIR);
 112         }
 113
 114         if(result >= UNIX_PATH_MAX) {
 115                 ERR("string overflow allocating socket name");
 116                 return -1;
 117         }
 118
 119         asprintf(&msg, "collect %d %s", pid, channel);
 120
 121         /* don't signal it because it's the daemon */
 122         result = ustcomm_connect_path(path, &conn, -1);
 123         if(result == -1) {
 124                 WARN("ustcomm_connect_path failed");
 125                 retval = -1;
 126                 goto del_string;
 127         }
 128
 129         result = ustcomm_send_request(&conn, msg, NULL);
 130         if(result == -1) {
 131                 WARN("ustcomm_send_request failed");
 132                 retval = -1;
 133                 goto disconnect;
 134         }
 135
 136         disconnect:
 137         ustcomm_disconnect(&conn);
 138         del_string:
 139         free(msg);
 140
 141         return retval;
 142 }
 143
 144 /* returns 1 to indicate a message was received
 145  * returns 0 to indicate no message was received (cannot happen)
 146  * returns -1 to indicate an error
 147  */
 148
 149 static int recv_message_fd(int fd, char **msg, struct ustcomm_source *src)
 150 {
 151         int result;
 152
 153         *msg = (char *) malloc(MSG_MAX+1);
 154
 155         result = recv(fd, *msg, MSG_MAX, 0);
 156         if(result == -1) {
 157                 PERROR("recv");
 158                 return -1;
 159         }
 160
 161         (*msg)[result] = '\0';
 162
 163         DBG("ustcomm_app_recv_message: result is %d, message is %s", result, (*msg));
 164
 165         if(src)
 166                 src->fd = fd;
 167
 168         return 1;
 169 }
 170
 171 int ustcomm_send_reply(struct ustcomm_server *server, char *msg, struct ustcomm_source *src)
 172 {
 173         int result;
 174
 175         result = send_message_fd(src->fd, msg);
 176         if(result < 0) {
 177                 ERR("error in send_message_fd");
 178                 return -1;
 179         }
 180
 181         return 0;
 182 }
 183
 184 /* Called after a fork. */
 185
 186 int ustcomm_close_all_connections(struct ustcomm_server *server)
 187 {
 188         struct ustcomm_connection *conn;
 189         struct ustcomm_connection *deletable_conn = NULL;
 190
 191         list_for_each_entry(conn, &server->connections, list) {
 192                 free(deletable_conn);
 193                 deletable_conn = conn;
 194                 close(conn->fd);
 195                 list_del(&conn->list);
 196         }
 197
 198         return 0;
 199 }
 200
 201 /* @timeout: max blocking time in milliseconds, -1 means infinity
 202  *
 203  * returns 1 to indicate a message was received
 204  * returns 0 to indicate no message was received
 205  * returns -1 to indicate an error
 206  */
 207
 208 int ustcomm_recv_message(struct ustcomm_server *server, char **msg, struct ustcomm_source *src, int timeout)
 209 {
 210         struct pollfd *fds;
 211         struct ustcomm_connection *conn;
 212         int result;
 213         int retval;
 214
 215         for(;;) {
 216                 int idx = 0;
 217                 int n_fds = 1;
 218
 219                 list_for_each_entry(conn, &server->connections, list) {
 220                         n_fds++;
 221                 }
 222
 223                 fds = (struct pollfd *) malloc(n_fds * sizeof(struct pollfd));
 224                 if(fds == NULL) {
 225                         ERR("malloc returned NULL");
 226                         return -1;
 227                 }
 228
 229                 /* special idx 0 is for listening socket */
 230                 fds[idx].fd = server->listen_fd;
 231                 fds[idx].events = POLLIN;
 232                 idx++;
 233
 234                 list_for_each_entry(conn, &server->connections, list) {
 235                         fds[idx].fd = conn->fd;
 236                         fds[idx].events = POLLIN;
 237                         idx++;
 238                 }
 239
 240                 while((result = poll(fds, n_fds, timeout)) == -1 && errno == EINTR)
 241                         /* nothing */;
 242                 if(result == -1) {
 243                         PERROR("poll");
 244                         return -1;
 245                 }
 246
 247                 if(result == 0)
 248                         return 0;
 249
 250                 if(fds[0].revents) {
 251                         struct ustcomm_connection *newconn;
 252                         int newfd;
 253
 254                         result = newfd = accept(server->listen_fd, NULL, NULL);
 255                         if(result == -1) {
 256                                 PERROR("accept");
 257                                 return -1;
 258                         }
 259
 260                         newconn = (struct ustcomm_connection *) malloc(sizeof(struct ustcomm_connection));
 261                         if(newconn == NULL) {
 262                                 ERR("malloc returned NULL");
 263                                 return -1;
 264                         }
 265
 266                         newconn->fd = newfd;
 267
 268                         list_add(&newconn->list, &server->connections);
 269                 }
 270
 271                 for(idx=1; idx<n_fds; idx++) {
 272                         if(fds[idx].revents) {
 273                                 retval = recv_message_fd(fds[idx].fd, msg, src);
 274                                 if(**msg == 0) {
 275                                         /* connection finished */
 276                                         close(fds[idx].fd);
 277
 278                                         list_for_each_entry(conn, &server->connections, list) {
 279                                                 if(conn->fd == fds[idx].fd) {
 280                                                         list_del(&conn->list);
 281                                                         break;
 282                                                 }
 283                                         }
 284                                 }
 285                                 else {
 286                                         goto free_fds_return;
 287                                 }
 288                         }
 289                 }
 290
 291                 free(fds);
 292         }
 293
 294 free_fds_return:
 295         free(fds);
 296         return retval;
 297 }
 298
 299 int ustcomm_ustd_recv_message(struct ustcomm_ustd *ustd, char **msg, struct ustcomm_source *src, int timeout)
 300 {
 301         return ustcomm_recv_message(&ustd->server, msg, src, timeout);
 302 }
 303
 304 int ustcomm_app_recv_message(struct ustcomm_app *app, char **msg, struct ustcomm_source *src, int timeout)
 305 {
 306         return ustcomm_recv_message(&app->server, msg, src, timeout);
 307 }
 308
 309 /* This removes src from the list of active connections of app.
 310  */
 311
 312 int ustcomm_app_detach_client(struct ustcomm_app *app, struct ustcomm_source *src)
 313 {
 314         struct ustcomm_server *server = (struct ustcomm_server *)app;
 315         struct ustcomm_connection *conn;
 316
 317         list_for_each_entry(conn, &server->connections, list) {
 318                 if(conn->fd == src->fd) {
 319                         list_del(&conn->list);
 320                         goto found;
 321                 }
 322         }
 323
 324         return -1;
 325 found:
 326         return src->fd;
 327 }
 328
 329 static int init_named_socket(const char *name, char **path_out)
 330 {
 331         int result;
 332         int fd;
 333
 334         struct sockaddr_un addr;
 335
 336         result = fd = socket(PF_UNIX, SOCK_STREAM, 0);
 337         if(result == -1) {
 338                 PERROR("socket");
 339                 return -1;
 340         }
 341
 342         addr.sun_family = AF_UNIX;
 343
 344         strncpy(addr.sun_path, name, UNIX_PATH_MAX);
 345         addr.sun_path[UNIX_PATH_MAX-1] = '\0';
 346
 347         result = access(name, F_OK);
 348         if(result == 0) {
 349                 /* file exists */
 350                 result = unlink(name);
 351                 if(result == -1) {
 352                         PERROR("unlink of socket file");
 353                         goto close_sock;
 354                 }
 355                 WARN("socket already exists; overwriting");
 356         }
 357
 358         result = bind(fd, (struct sockaddr *)&addr, sizeof(addr));
 359         if(result == -1) {
 360                 PERROR("bind");
 361                 goto close_sock;
 362         }
 363
 364         result = listen(fd, 1);
 365         if(result == -1) {
 366                 PERROR("listen");
 367                 goto close_sock;
 368         }
 369
 370         if(path_out) {
 371                 *path_out = strdup(addr.sun_path);
 372         }
 373
 374         return fd;
 375
 376         close_sock:
 377         close(fd);
 378
 379         return -1;
 380 }
 381
 382 /*
 383  * Return value:
 384  *   0: Success, but no reply because recv() returned 0
 385  *   1: Success
 386  *   -1: Error
 387  *
 388  * On error, the error message is printed, except on
 389  * ECONNRESET, which is normal when the application dies.
 390  */
 391
 392 int ustcomm_send_request(struct ustcomm_connection *conn, const char *req, char **reply)
 393 {
 394         int result;
 395
 396         result = send(conn->fd, req, strlen(req), MSG_NOSIGNAL);
 397         if(result == -1) {
 398                 if(errno != EPIPE)
 399                         PERROR("send");
 400                 return -1;
 401         }
 402
 403         if(!reply)
 404                 return 1;
 405
 406         *reply = (char *) malloc(MSG_MAX+1);
 407         result = recv(conn->fd, *reply, MSG_MAX, 0);
 408         if(result == -1) {
 409                 if(errno != ECONNRESET)
 410                         PERROR("recv");
 411                 return -1;
 412         }
 413         else if(result == 0) {
 414                 return 0;
 415         }
 416
 417         (*reply)[result] = '\0';
 418
 419         return 1;
 420 }
 421
 422 int ustcomm_connect_path(const char *path, struct ustcomm_connection *conn, pid_t signalpid)
 423 {
 424         int fd;
 425         int result;
 426         struct sockaddr_un addr;
 427
 428         result = fd = socket(PF_UNIX, SOCK_STREAM, 0);
 429         if(result == -1) {
 430                 PERROR("socket");
 431                 return -1;
 432         }
 433
 434         addr.sun_family = AF_UNIX;
 435
 436         result = snprintf(addr.sun_path, UNIX_PATH_MAX, "%s", path);
 437         if(result >= UNIX_PATH_MAX) {
 438                 ERR("string overflow allocating socket name");
 439                 return -1;
 440         }
 441
 442         if(signalpid >= 0) {
 443                 result = signal_process(signalpid);
 444                 if(result == -1) {
 445                         ERR("could not signal process");
 446                         return -1;
 447                 }
 448         }
 449
 450         result = connect(fd, (struct sockaddr *)&addr, sizeof(addr));
 451         if(result == -1) {
 452                 PERROR("connect");
 453                 return -1;
 454         }
 455
 456         conn->fd = fd;
 457
 458         return 0;
 459 }
 460
 461 int ustcomm_disconnect(struct ustcomm_connection *conn)
 462 {
 463         return close(conn->fd);
 464 }
 465
 466 int ustcomm_connect_app(pid_t pid, struct ustcomm_connection *conn)
 467 {
 468         int result;
 469         char path[UNIX_PATH_MAX];
 470
 471
 472         result = snprintf(path, UNIX_PATH_MAX, "%s/%d", SOCK_DIR, pid);
 473         if(result >= UNIX_PATH_MAX) {
 474                 ERR("string overflow allocating socket name");
 475                 return -1;
 476         }
 477
 478         return ustcomm_connect_path(path, conn, pid);
 479 }
 480
 481 static int ensure_dir_exists(const char *dir)
 482 {
 483         struct stat st;
 484         int result;
 485
 486         if(!strcmp(dir, ""))
 487                 return -1;
 488
 489         result = stat(dir, &st);
 490         if(result == -1 && errno != ENOENT) {
 491                 return -1;
 492         }
 493         else if(result == -1) {
 494                 /* ENOENT */
 495                 char buf[200];
 496                 int result;
 497
 498                 result = snprintf(buf, sizeof(buf), "mkdir -p \"%s\"", dir);
 499                 if(result >= sizeof(buf)) {
 500                         ERR("snprintf buffer overflow");
 501                         return -1;
 502                 }
 503                 result = system(buf);
 504                 if(result != 0) {
 505                         ERR("executing command %s", buf);
 506                         return -1;
 507                 }
 508         }
 509
 510         return 0;
 511 }
 512
 513 /* Called by an application to initialize its server so daemons can
 514  * connect to it.
 515  */
 516
 517 int ustcomm_init_app(pid_t pid, struct ustcomm_app *handle)
 518 {
 519         int result;
 520         char *name;
 521
 522         result = asprintf(&name, "%s/%d", SOCK_DIR, (int)pid);
 523         if(result >= UNIX_PATH_MAX) {
 524                 ERR("string overflow allocating socket name");
 525                 return -1;
 526         }
 527
 528         result = ensure_dir_exists(SOCK_DIR);
 529         if(result == -1) {
 530                 ERR("Unable to create socket directory %s", SOCK_DIR);
 531                 return -1;
 532         }
 533
 534         handle->server.listen_fd = init_named_socket(name, &(handle->server.socketpath));
 535         if(handle->server.listen_fd < 0) {
 536                 ERR("Error initializing named socket (%s). Check that directory exists and that it is writable.", name);
 537                 goto free_name;
 538         }
 539         free(name);
 540
 541         INIT_LIST_HEAD(&handle->server.connections);
 542
 543         return 0;
 544
 545 free_name:
 546         free(name);
 547         return -1;
 548 }
 549
 550 /* Used by the daemon to initialize its server so applications
 551  * can connect to it.
 552  */
 553
 554 int ustcomm_init_ustd(struct ustcomm_ustd *handle, const char *sock_path)
 555 {
 556         char *name;
 557         int retval = 0;
 558
 559         if(sock_path) {
 560                 asprintf(&name, "%s", sock_path);
 561         }
 562         else {
 563                 int result;
 564
 565                 /* Only check if socket dir exists if we are using the default directory */
 566                 result = ensure_dir_exists(SOCK_DIR);
 567                 if(result == -1) {
 568                         ERR("Unable to create socket directory %s", SOCK_DIR);
 569                         return -1;
 570                 }
 571
 572                 asprintf(&name, "%s/%s", SOCK_DIR, "ustd");
 573         }
 574
 575         handle->server.listen_fd = init_named_socket(name, &handle->server.socketpath);
 576         if(handle->server.listen_fd < 0) {
 577                 ERR("error initializing named socket at %s", name);
 578                 retval = -1;
 579                 goto free_name;
 580         }
 581
 582         INIT_LIST_HEAD(&handle->server.connections);
 583
 584 free_name:
 585         free(name);
 586
 587         return retval;
 588 }
 589
 590 void ustcomm_fini_app(struct ustcomm_app *handle)
 591 {
 592         int result;
 593         struct stat st;
 594
 595         /* Destroy socket */
 596         result = stat(handle->server.socketpath, &st);
 597         if(result == -1) {
 598                 PERROR("stat (%s)", handle->server.socketpath);
 599                 return;
 600         }
 601
 602         /* Paranoid check before deleting. */
 603         result = S_ISSOCK(st.st_mode);
 604         if(!result) {
 605                 ERR("The socket we are about to delete is not a socket.");
 606                 return;
 607         }
 608
 609         result = unlink(handle->server.socketpath);
 610         if(result == -1) {
 611                 PERROR("unlink");
 612         }
 613 }
 614
 615 static char *find_tok(char *str)
 616 {
 617         while(*str == ' ') {
 618                 str++;
 619
 620                 if(*str == 0)
 621                         return NULL;
 622         }
 623
 624         return str;
 625 }
 626
 627 static char *find_sep(char *str)
 628 {
 629         while(*str != ' ') {
 630                 str++;
 631
 632                 if(*str == 0)
 633                         break;
 634         }
 635
 636         return str;
 637 }
 638
 639 int nth_token_is(char *str, char *token, int tok_no)
 640 {
 641         int i;
 642         char *start;
 643         char *end;
 644
 645         for(i=0; i<=tok_no; i++) {
 646                 str = find_tok(str);
 647                 if(str == NULL)
 648                         return -1;
 649
 650                 start = str;
 651
 652                 str = find_sep(str);
 653                 if(str == NULL)
 654                         return -1;
 655
 656                 end = str;
 657         }
 658
 659         if(end-start != strlen(token))
 660                 return 0;
 661
 662         if(strncmp(start, token, end-start))
 663                 return 0;
 664
 665         return 1;
 666 }
 667
 668 char *nth_token(char *str, int tok_no)
 669 {
 670         static char *retval = NULL;
 671         int i;
 672         char *start;
 673         char *end;
 674
 675         for(i=0; i<=tok_no; i++) {
 676                 str = find_tok(str);
 677                 if(str == NULL)
 678                         return NULL;
 679
 680                 start = str;
 681
 682                 str = find_sep(str);
 683                 if(str == NULL)
 684                         return NULL;
 685
 686                 end = str;
 687         }
 688
 689         if(retval) {
 690                 free(retval);
 691                 retval = NULL;
 692         }
 693
 694         asprintf(&retval, "%.*s", (int)(end-start), start);
 695
 696         return retval;
 697 }
 698