src/frontend/sock.c

   1 /*
   2  * SysDB - src/frontend/sock.c
   3  * Copyright (C) 2013 Sebastian 'tokkee' Harl <sh@tokkee.org>
   4  * All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   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  *
  15  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  16  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
  17  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  18  * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR
  19  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  20  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  21  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
  22  * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
  23  * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
  24  * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
  25  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  26  */
  27
  28 #if HAVE_CONFIG_H
  29 #       include "config.h"
  30 #endif /* HAVE_CONFIG_H */
  31
  32 #include "sysdb.h"
  33 #include "core/object.h"
  34 #include "frontend/connection-private.h"
  35 #include "frontend/sock.h"
  36
  37 #include "utils/channel.h"
  38 #include "utils/error.h"
  39 #include "utils/llist.h"
  40 #include "utils/os.h"
  41 #include "utils/strbuf.h"
  42
  43 #include <assert.h>
  44 #include <errno.h>
  45
  46 #include <stdio.h>
  47 #include <stdlib.h>
  48 #include <string.h>
  49
  50 #include <unistd.h>
  51
  52 #include <sys/time.h>
  53 #include <sys/types.h>
  54 #include <sys/select.h>
  55 #include <sys/socket.h>
  56 #include <sys/param.h>
  57 #include <sys/un.h>
  58
  59 #ifdef HAVE_UCRED_H
  60 #       include <ucred.h>
  61 #endif
  62 #ifdef HAVE_SYS_UCRED_H
  63 #       include <sys/ucred.h>
  64 #endif
  65
  66 #include <pwd.h>
  67
  68 #include <netdb.h>
  69 #include <libgen.h>
  70 #include <pthread.h>
  71
  72 /*
  73  * private data types
  74  */
  75
  76 typedef struct {
  77         char *address;
  78         int   type;
  79
  80         int sock_fd;
  81         int (*accept)(sdb_conn_t *);
  82         int (*peer)(sdb_conn_t *);
  83 } listener_t;
  84
  85 typedef struct {
  86         int type;
  87         const char *prefix;
  88
  89         int (*open)(listener_t *);
  90         void (*close)(listener_t *);
  91 } fe_listener_impl_t;
  92
  93 struct sdb_fe_socket {
  94         listener_t *listeners;
  95         size_t listeners_num;
  96
  97         sdb_llist_t *open_connections;
  98
  99         /* channel used for communication between main
 100          * and connection handler threads */
 101         sdb_channel_t *chan;
 102 };
 103
 104 /*
 105  * connection management functions
 106  */
 107
 108 static int
 109 unixsock_peer(sdb_conn_t *conn)
 110 {
 111         uid_t uid;
 112
 113         struct passwd pw_entry;
 114         struct passwd *result = NULL;
 115         char buf[1024];
 116
 117 #ifdef SO_PEERCRED
 118         struct ucred cred;
 119         socklen_t len = sizeof(cred);
 120
 121         if (getsockopt(conn->fd, SOL_SOCKET, SO_PEERCRED, &cred, &len)
 122                         || (len != sizeof(cred))) {
 123                 char errbuf[1024];
 124                 sdb_log(SDB_LOG_ERR, "frontend: Failed to determine peer for "
 125                                 "connection conn#%i: %s", conn->fd,
 126                                 sdb_strerror(errno, errbuf, sizeof(errbuf)));
 127                 return -1;
 128         }
 129         uid = cred.uid;
 130 #else /* SO_PEERCRED */
 131         sdb_log(SDB_LOG_ERR, "frontend: Failed to determine peer for "
 132                         "connection conn#%i: operation not supported", conn->fd);
 133         return -1;
 134 #endif
 135
 136         memset(&pw_entry, 0, sizeof(pw_entry));
 137         if (getpwuid_r(uid, &pw_entry, buf, sizeof(buf), &result) || (! result)
 138                         || (! (conn->username = strdup(result->pw_name)))) {
 139                 char errbuf[1024];
 140                 sdb_log(SDB_LOG_ERR, "frontend: Failed to determine peer for "
 141                                 "connection conn#%i: %s", conn->fd,
 142                                 sdb_strerror(errno, errbuf, sizeof(errbuf)));
 143                 return -1;
 144         }
 145         return 0;
 146 } /* unixsock_peer */
 147
 148 static int
 149 open_unixsock(listener_t *listener)
 150 {
 151         char *addr_copy;
 152         char *base_dir;
 153         struct sockaddr_un sa;
 154         int status;
 155
 156         listener->sock_fd = socket(AF_UNIX, SOCK_STREAM, 0);
 157         if (listener->sock_fd < 0) {
 158                 char buf[1024];
 159                 sdb_log(SDB_LOG_ERR, "frontend: Failed to open UNIX socket %s: %s",
 160                                 listener->address, sdb_strerror(errno, buf, sizeof(buf)));
 161                 return -1;
 162         }
 163
 164         memset(&sa, 0, sizeof(sa));
 165         sa.sun_family = AF_UNIX;
 166         strncpy(sa.sun_path, listener->address, sizeof(sa.sun_path));
 167
 168         addr_copy = strdup(listener->address);
 169         if (! addr_copy) {
 170                 char errbuf[1024];
 171                 sdb_log(SDB_LOG_ERR, "frontend: strdup failed: %s",
 172                                 sdb_strerror(errno, errbuf, sizeof(errbuf)));
 173                 return -1;
 174         }
 175         base_dir = dirname(addr_copy);
 176
 177         /* ensure that the directory exists */
 178         if (sdb_mkdir_all(base_dir, 0777)) {
 179                 char errbuf[1024];
 180                 sdb_log(SDB_LOG_ERR, "frontend: Failed to create directory '%s': %s",
 181                                 base_dir, sdb_strerror(errno, errbuf, sizeof(errbuf)));
 182                 free(addr_copy);
 183                 return -1;
 184         }
 185         free(addr_copy);
 186
 187         if (unlink(listener->address) && (errno != ENOENT)) {
 188                 char errbuf[1024];
 189                 sdb_log(SDB_LOG_WARNING, "frontend: Failed to remove stale UNIX "
 190                                 "socket %s: %s", listener->address,
 191                                 sdb_strerror(errno, errbuf, sizeof(errbuf)));
 192         }
 193
 194         status = bind(listener->sock_fd, (struct sockaddr *)&sa, sizeof(sa));
 195         if (status) {
 196                 char buf[1024];
 197                 sdb_log(SDB_LOG_ERR, "frontend: Failed to bind to UNIX socket %s: %s",
 198                                 listener->address, sdb_strerror(errno, buf, sizeof(buf)));
 199                 return -1;
 200         }
 201
 202         listener->peer = unixsock_peer;
 203         return 0;
 204 } /* open_unixsock */
 205
 206 static void
 207 close_unixsock(listener_t *listener)
 208 {
 209         assert(listener);
 210
 211         if (! listener->address)
 212                 return;
 213
 214         if (listener->sock_fd >= 0)
 215                 close(listener->sock_fd);
 216         listener->sock_fd = -1;
 217
 218         unlink(listener->address);
 219 } /* close_unixsock */
 220
 221 static int
 222 open_tcp(listener_t *listener)
 223 {
 224         struct addrinfo *ai, *ai_list = NULL;
 225         int status;
 226
 227         assert(listener);
 228
 229         if ((status = sdb_resolve(SDB_NET_TCP, listener->address, &ai_list))) {
 230                 sdb_log(SDB_LOG_ERR, "frontend: Failed to resolve '%s': %s",
 231                                 listener->address, gai_strerror(status));
 232                 return -1;
 233         }
 234
 235         for (ai = ai_list; ai != NULL; ai = ai->ai_next) {
 236                 char errbuf[1024];
 237                 int reuse = 1;
 238
 239                 listener->sock_fd = socket(ai->ai_family,
 240                                 ai->ai_socktype, ai->ai_protocol);
 241                 if (listener->sock_fd < 0) {
 242                         sdb_log(SDB_LOG_ERR, "frontend: Failed to open socket for %s: %s",
 243                                         listener->address,
 244                                         sdb_strerror(errno, errbuf, sizeof(errbuf)));
 245                         continue;
 246                 }
 247
 248                 if (setsockopt(listener->sock_fd, SOL_SOCKET, SO_REUSEADDR,
 249                                         &reuse, sizeof(reuse)) < 0) {
 250                         sdb_log(SDB_LOG_ERR, "frontend: Failed to set socket option: %s",
 251                                         sdb_strerror(errno, errbuf, sizeof(errbuf)));
 252                         close(listener->sock_fd);
 253                         listener->sock_fd = -1;
 254                         continue;
 255                 }
 256
 257                 if (bind(listener->sock_fd, ai->ai_addr, ai->ai_addrlen) < 0) {
 258                         char host[1024], port[32];
 259                         getnameinfo(ai->ai_addr, ai->ai_addrlen, host, sizeof(host),
 260                                         port, sizeof(port), NI_NUMERICHOST | NI_NUMERICSERV);
 261                         sdb_log(SDB_LOG_ERR, "frontend: Failed to bind to %s:%s: %s",
 262                                         host, port, sdb_strerror(errno, errbuf, sizeof(errbuf)));
 263                         close(listener->sock_fd);
 264                         listener->sock_fd = -1;
 265                         continue;
 266                 }
 267                 break;
 268         }
 269         freeaddrinfo(ai_list);
 270
 271         if (listener->sock_fd < 0)
 272                 return -1;
 273         return 0;
 274 } /* open_tcp */
 275
 276 static void
 277 close_tcp(listener_t *listener)
 278 {
 279         assert(listener);
 280
 281         if (listener->sock_fd >= 0)
 282                 close(listener->sock_fd);
 283         listener->sock_fd = -1;
 284 } /* close_tcp */
 285
 286 /*
 287  * private variables
 288  */
 289
 290 /* the enum has to be sorted the same as the implementations array
 291  * to ensure that the type may be used as index into the array */
 292 enum {
 293         LISTENER_TCP = 0, /* this is the default */
 294         LISTENER_UNIXSOCK,
 295 };
 296 static fe_listener_impl_t listener_impls[] = {
 297         { LISTENER_TCP,      "tcp",  open_tcp,      close_tcp },
 298         { LISTENER_UNIXSOCK, "unix", open_unixsock, close_unixsock },
 299 };
 300
 301 /*
 302  * private helper functions
 303  */
 304
 305 static int
 306 listener_listen(listener_t *listener)
 307 {
 308         assert(listener);
 309
 310         /* try to reopen */
 311         if (listener->sock_fd < 0)
 312                 if (listener_impls[listener->type].open(listener))
 313                         return -1;
 314         assert(listener->sock_fd >= 0);
 315
 316         if (listen(listener->sock_fd, /* backlog = */ 32)) {
 317                 char buf[1024];
 318                 sdb_log(SDB_LOG_ERR, "frontend: Failed to listen on socket %s: %s",
 319                                 listener->address, sdb_strerror(errno, buf, sizeof(buf)));
 320                 return -1;
 321         }
 322         return 0;
 323 } /* listener_listen */
 324
 325 static void
 326 listener_close(listener_t *listener)
 327 {
 328         assert(listener);
 329
 330         if (listener_impls[listener->type].close)
 331                 listener_impls[listener->type].close(listener);
 332
 333         if (listener->sock_fd >= 0)
 334                 close(listener->sock_fd);
 335         listener->sock_fd = -1;
 336 } /* listener_close */
 337
 338 static int
 339 get_type(const char *address)
 340 {
 341         char *sep;
 342         size_t len;
 343         size_t i;
 344
 345         if (*address == '/')
 346                 return LISTENER_UNIXSOCK;
 347         sep = strchr(address, (int)':');
 348         if (! sep)
 349                 return listener_impls[0].type;
 350
 351         assert(sep > address);
 352         len = (size_t)(sep - address);
 353
 354         for (i = 0; i < SDB_STATIC_ARRAY_LEN(listener_impls); ++i) {
 355                 fe_listener_impl_t *impl = listener_impls + i;
 356
 357                 if (!strncmp(address, impl->prefix, len)) {
 358                         assert(impl->type == (int)i);
 359                         return impl->type;
 360                 }
 361         }
 362         return -1;
 363 } /* get_type */
 364
 365 static void
 366 listener_destroy(listener_t *listener)
 367 {
 368         if (! listener)
 369                 return;
 370
 371         listener_close(listener);
 372
 373         if (listener->address)
 374                 free(listener->address);
 375         listener->address = NULL;
 376 } /* listener_destroy */
 377
 378 static listener_t *
 379 listener_create(sdb_fe_socket_t *sock, const char *address)
 380 {
 381         listener_t *listener;
 382         size_t len;
 383         int type;
 384
 385         type = get_type(address);
 386         if (type < 0) {
 387                 sdb_log(SDB_LOG_ERR, "frontend: Unsupported address type specified "
 388                                 "in listen address '%s'", address);
 389                 return NULL;
 390         }
 391
 392         listener = realloc(sock->listeners,
 393                         (sock->listeners_num + 1) * sizeof(*sock->listeners));
 394         if (! listener) {
 395                 char buf[1024];
 396                 sdb_log(SDB_LOG_ERR, "frontend: Failed to allocate memory: %s",
 397                                 sdb_strerror(errno, buf, sizeof(buf)));
 398                 return NULL;
 399         }
 400
 401         sock->listeners = listener;
 402         listener = sock->listeners + sock->listeners_num;
 403
 404         len = strlen(listener_impls[type].prefix);
 405         if ((! strncmp(address, listener_impls[type].prefix, len))
 406                         && (address[len] == ':'))
 407                 address += strlen(listener_impls[type].prefix) + 1;
 408
 409         listener->sock_fd = -1;
 410         listener->address = strdup(address);
 411         if (! listener->address) {
 412                 char buf[1024];
 413                 sdb_log(SDB_LOG_ERR, "frontend: Failed to allocate memory: %s",
 414                                 sdb_strerror(errno, buf, sizeof(buf)));
 415                 listener_destroy(listener);
 416                 return NULL;
 417         }
 418         listener->type = type;
 419         listener->accept = NULL;
 420         listener->peer = NULL;
 421
 422         if (listener_impls[type].open(listener)) {
 423                 /* prints error */
 424                 listener_destroy(listener);
 425                 return NULL;
 426         }
 427
 428         ++sock->listeners_num;
 429         return listener;
 430 } /* listener_create */
 431
 432 static void
 433 socket_clear(sdb_fe_socket_t *sock)
 434 {
 435         size_t i;
 436
 437         assert(sock);
 438         for (i = 0; i < sock->listeners_num; ++i)
 439                 listener_destroy(sock->listeners + i);
 440         if (sock->listeners)
 441                 free(sock->listeners);
 442         sock->listeners = NULL;
 443         sock->listeners_num = 0;
 444 } /* socket_clear */
 445
 446 static void
 447 socket_close(sdb_fe_socket_t *sock)
 448 {
 449         size_t i;
 450
 451         assert(sock);
 452         for (i = 0; i < sock->listeners_num; ++i)
 453                 listener_close(sock->listeners + i);
 454 } /* socket_close */
 455
 456 /*
 457  * connection handler functions
 458  */
 459
 460 static void *
 461 connection_handler(void *data)
 462 {
 463         sdb_fe_socket_t *sock = data;
 464
 465         assert(sock);
 466
 467         while (42) {
 468                 struct timespec timeout = { 0, 500000000 }; /* .5 seconds */
 469                 sdb_conn_t *conn;
 470                 int status;
 471
 472                 errno = 0;
 473                 status = sdb_channel_select(sock->chan, /* read */ NULL, &conn,
 474                                 /* write */ NULL, NULL, &timeout);
 475                 if (status) {
 476                         char buf[1024];
 477
 478                         if (errno == ETIMEDOUT)
 479                                 continue;
 480                         if (errno == EBADF) /* channel shut down */
 481                                 break;
 482
 483                         sdb_log(SDB_LOG_ERR, "frontend: Failed to read from channel: %s",
 484                                         sdb_strerror(errno, buf, sizeof(buf)));
 485                         continue;
 486                 }
 487
 488                 status = (int)sdb_connection_handle(conn);
 489                 if (status <= 0) {
 490                         /* error or EOF -> close connection */
 491                         sdb_object_deref(SDB_OBJ(conn));
 492                         continue;
 493                 }
 494
 495                 /* return the connection to the main loop */
 496                 if (sdb_llist_append(sock->open_connections, SDB_OBJ(conn))) {
 497                         sdb_log(SDB_LOG_ERR, "frontend: Failed to re-append "
 498                                         "connection %s to list of open connections",
 499                                         SDB_OBJ(conn)->name);
 500                 }
 501
 502                 /* pass ownership back to list; or destroy in case of an error */
 503                 sdb_object_deref(SDB_OBJ(conn));
 504         }
 505         return NULL;
 506 } /* connection_handler */
 507
 508 static int
 509 connection_accept(sdb_fe_socket_t *sock, listener_t *listener)
 510 {
 511         sdb_object_t *obj;
 512         int status;
 513
 514         obj = SDB_OBJ(sdb_connection_accept(listener->sock_fd));
 515         if (! obj)
 516                 return -1;
 517
 518         if (listener->accept && listener->accept(CONN(obj))) {
 519                 /* accept() is expected to log an error */
 520                 sdb_object_deref(obj);
 521                 return -1;
 522         }
 523         if (listener->peer && listener->peer(CONN(obj))) {
 524                 /* peer() is expected to log an error */
 525                 sdb_object_deref(obj);
 526                 return -1;
 527         }
 528
 529         status = sdb_llist_append(sock->open_connections, obj);
 530         if (status)
 531                 sdb_log(SDB_LOG_ERR, "frontend: Failed to append "
 532                                 "connection %s to list of open connections",
 533                                 obj->name);
 534
 535         /* hand ownership over to the list; or destroy in case of an error */
 536         sdb_object_deref(obj);
 537         return status;
 538 } /* connection_accept */
 539
 540 static int
 541 socket_handle_incoming(sdb_fe_socket_t *sock,
 542                 fd_set *ready, fd_set *exceptions)
 543 {
 544         sdb_llist_iter_t *iter;
 545         size_t i;
 546
 547         for (i = 0; i < sock->listeners_num; ++i) {
 548                 listener_t *listener = sock->listeners + i;
 549                 if (FD_ISSET(listener->sock_fd, ready))
 550                         if (connection_accept(sock, listener))
 551                                 continue;
 552         }
 553
 554         iter = sdb_llist_get_iter(sock->open_connections);
 555         if (! iter) {
 556                 sdb_log(SDB_LOG_ERR, "frontend: Failed to acquire iterator "
 557                                 "for open connections");
 558                 return -1;
 559         }
 560
 561         while (sdb_llist_iter_has_next(iter)) {
 562                 sdb_object_t *obj = sdb_llist_iter_get_next(iter);
 563
 564                 if (FD_ISSET(CONN(obj)->fd, exceptions)) {
 565                         sdb_log(SDB_LOG_INFO, "Exception on fd %d",
 566                                         CONN(obj)->fd);
 567                         /* close the connection */
 568                         sdb_llist_iter_remove_current(iter);
 569                         sdb_object_deref(obj);
 570                         continue;
 571                 }
 572
 573                 if (FD_ISSET(CONN(obj)->fd, ready)) {
 574                         sdb_llist_iter_remove_current(iter);
 575                         sdb_channel_write(sock->chan, &obj);
 576                 }
 577         }
 578         sdb_llist_iter_destroy(iter);
 579         return 0;
 580 } /* socket_handle_incoming */
 581
 582 /*
 583  * public API
 584  */
 585
 586 sdb_fe_socket_t *
 587 sdb_fe_sock_create(void)
 588 {
 589         sdb_fe_socket_t *sock;
 590
 591         sock = calloc(1, sizeof(*sock));
 592         if (! sock)
 593                 return NULL;
 594
 595         sock->open_connections = sdb_llist_create();
 596         if (! sock->open_connections) {
 597                 sdb_fe_sock_destroy(sock);
 598                 return NULL;
 599         }
 600         return sock;
 601 } /* sdb_fe_sock_create */
 602
 603 void
 604 sdb_fe_sock_destroy(sdb_fe_socket_t *sock)
 605 {
 606         if (! sock)
 607                 return;
 608
 609         socket_clear(sock);
 610
 611         sdb_llist_destroy(sock->open_connections);
 612         sock->open_connections = NULL;
 613         free(sock);
 614 } /* sdb_fe_sock_destroy */
 615
 616 int
 617 sdb_fe_sock_add_listener(sdb_fe_socket_t *sock, const char *address)
 618 {
 619         listener_t *listener;
 620
 621         if ((! sock) || (! address))
 622                 return -1;
 623
 624         listener = listener_create(sock, address);
 625         if (! listener)
 626                 return -1;
 627         return 0;
 628 } /* sdb_fe_sock_add_listener */
 629
 630 void
 631 sdb_fe_sock_clear_listeners(sdb_fe_socket_t *sock)
 632 {
 633         if (! sock)
 634                 return;
 635
 636         socket_clear(sock);
 637 } /* sdb_fe_sock_clear_listeners */
 638
 639 int
 640 sdb_fe_sock_listen_and_serve(sdb_fe_socket_t *sock, sdb_fe_loop_t *loop)
 641 {
 642         fd_set sockets;
 643         int max_listen_fd = 0;
 644         size_t i;
 645
 646         pthread_t handler_threads[loop->num_threads];
 647         size_t num_threads;
 648
 649         if ((! sock) || (! sock->listeners_num) || sock->chan
 650                         || (! loop) || (loop->num_threads <= 0))
 651                 return -1;
 652
 653         if (! loop->do_loop)
 654                 return 0;
 655
 656         FD_ZERO(&sockets);
 657         for (i = 0; i < sock->listeners_num; ++i) {
 658                 listener_t *listener = sock->listeners + i;
 659
 660                 if (listener_listen(listener)) {
 661                         socket_close(sock);
 662                         return -1;
 663                 }
 664
 665                 FD_SET(listener->sock_fd, &sockets);
 666                 if (listener->sock_fd > max_listen_fd)
 667                         max_listen_fd = listener->sock_fd;
 668         }
 669
 670         sock->chan = sdb_channel_create(1024, sizeof(sdb_conn_t *));
 671         if (! sock->chan) {
 672                 socket_close(sock);
 673                 return -1;
 674         }
 675
 676         sdb_log(SDB_LOG_INFO, "frontend: Starting %zu connection "
 677                         "handler thread%s managing %zu listener%s",
 678                         loop->num_threads, loop->num_threads == 1 ? "" : "s",
 679                         sock->listeners_num, sock->listeners_num == 1 ? "" : "s");
 680
 681         num_threads = loop->num_threads;
 682         memset(&handler_threads, 0, sizeof(handler_threads));
 683         for (i = 0; i < num_threads; ++i) {
 684                 errno = 0;
 685                 if (pthread_create(&handler_threads[i], /* attr = */ NULL,
 686                                         connection_handler, /* arg = */ sock)) {
 687                         char errbuf[1024];
 688                         sdb_log(SDB_LOG_ERR, "frontend: Failed to create "
 689                                         "connection handler thread: %s",
 690                                         sdb_strerror(errno, errbuf, sizeof(errbuf)));
 691                         num_threads = i;
 692                         break;
 693                 }
 694         }
 695
 696         while (loop->do_loop && num_threads) {
 697                 struct timeval timeout = { 1, 0 }; /* one second */
 698                 sdb_llist_iter_t *iter;
 699
 700                 int max_fd = max_listen_fd;
 701                 fd_set ready;
 702                 fd_set exceptions;
 703                 int n;
 704
 705                 FD_ZERO(&ready);
 706                 FD_ZERO(&exceptions);
 707
 708                 ready = sockets;
 709
 710                 iter = sdb_llist_get_iter(sock->open_connections);
 711                 if (! iter) {
 712                         sdb_log(SDB_LOG_ERR, "frontend: Failed to acquire iterator "
 713                                         "for open connections");
 714                         break;
 715                 }
 716
 717                 while (sdb_llist_iter_has_next(iter)) {
 718                         sdb_object_t *obj = sdb_llist_iter_get_next(iter);
 719
 720                         if (CONN(obj)->fd < 0) {
 721                                 sdb_llist_iter_remove_current(iter);
 722                                 sdb_object_deref(obj);
 723                                 continue;
 724                         }
 725
 726                         FD_SET(CONN(obj)->fd, &ready);
 727                         FD_SET(CONN(obj)->fd, &exceptions);
 728
 729                         if (CONN(obj)->fd > max_fd)
 730                                 max_fd = CONN(obj)->fd;
 731                 }
 732                 sdb_llist_iter_destroy(iter);
 733
 734                 errno = 0;
 735                 n = select(max_fd + 1, &ready, NULL, &exceptions, &timeout);
 736                 if (n < 0) {
 737                         char buf[1024];
 738
 739                         if (errno == EINTR)
 740                                 continue;
 741
 742                         sdb_log(SDB_LOG_ERR, "frontend: Failed to monitor sockets: %s",
 743                                         sdb_strerror(errno, buf, sizeof(buf)));
 744                         break;
 745                 }
 746                 else if (! n)
 747                         continue;
 748
 749                 /* handle new and open connections */
 750                 if (socket_handle_incoming(sock, &ready, &exceptions))
 751                         break;
 752         }
 753
 754         socket_close(sock);
 755
 756         sdb_log(SDB_LOG_INFO, "frontend: Waiting for connection handler threads "
 757                         "to terminate");
 758         if (! sdb_channel_shutdown(sock->chan))
 759                 for (i = 0; i < num_threads; ++i)
 760                         pthread_join(handler_threads[i], NULL);
 761         /* else: we tried our best; let the operating system clean up */
 762
 763         sdb_channel_destroy(sock->chan);
 764         sock->chan = NULL;
 765
 766         if (! num_threads)
 767                 return -1;
 768         return 0;
 769 } /* sdb_fe_sock_listen_and_server */
 770
 771 /* vim: set tw=78 sw=4 ts=4 noexpandtab : */
 772