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 #include "sysdb.h"
  29 #include "core/error.h"
  30 #include "core/object.h"
  31 #include "frontend/sock.h"
  32
  33 #include "utils/channel.h"
  34 #include "utils/llist.h"
  35
  36 #include <assert.h>
  37
  38 #include <errno.h>
  39
  40 #include <stdio.h>
  41 #include <stdlib.h>
  42 #include <string.h>
  43
  44 #include <unistd.h>
  45
  46 #include <fcntl.h>
  47
  48 #include <sys/time.h>
  49 #include <sys/types.h>
  50 #include <sys/select.h>
  51 #include <sys/socket.h>
  52 #include <sys/un.h>
  53
  54 #include <pthread.h>
  55
  56 /* name of connection objects */
  57 #define CONN_FD_PREFIX "conn#"
  58 #define CONN_FD_PLACEHOLDER "XXXXXXX"
  59
  60 /*
  61  * private data types
  62  */
  63
  64 typedef struct {
  65         int fd;
  66         struct sockaddr_storage client_addr;
  67         socklen_t client_addr_len;
  68 } connection_t;
  69
  70 typedef struct {
  71         sdb_object_t super;
  72         connection_t conn;
  73 } connection_obj_t;
  74 #define CONN(obj) ((connection_obj_t *)(obj))
  75
  76 typedef struct {
  77         char *address;
  78         int   type;
  79
  80         int sock_fd;
  81 } listener_t;
  82
  83 typedef struct {
  84         int type;
  85         const char *prefix;
  86
  87         int (*opener)(listener_t *);
  88 } fe_listener_impl_t;
  89
  90 struct sdb_fe_socket {
  91         listener_t *listeners;
  92         size_t listeners_num;
  93
  94         sdb_llist_t *open_connections;
  95
  96         /* channel used for communication between main
  97          * and connection handler threads */
  98         sdb_channel_t *chan;
  99 };
 100
 101 /*
 102  * connection management functions
 103  */
 104
 105 static int
 106 open_unix_sock(listener_t *listener)
 107 {
 108         struct sockaddr_un sa;
 109         int status;
 110
 111         listener->sock_fd = socket(AF_UNIX, SOCK_STREAM, 0);
 112         if (listener->sock_fd < 0) {
 113                 char buf[1024];
 114                 sdb_log(SDB_LOG_ERR, "frontend: Failed to open UNIX socket %s: %s",
 115                                 listener->address, sdb_strerror(errno, buf, sizeof(buf)));
 116                 return -1;
 117         }
 118
 119         memset(&sa, 0, sizeof(sa));
 120         sa.sun_family = AF_UNIX;
 121         strncpy(sa.sun_path, listener->address + strlen("unix:"),
 122                         sizeof(sa.sun_path));
 123
 124         status = bind(listener->sock_fd, (struct sockaddr *)&sa, sizeof(sa));
 125         if (status) {
 126                 char buf[1024];
 127                 sdb_log(SDB_LOG_ERR, "frontend: Failed to bind to UNIX socket %s: %s",
 128                                 listener->address, sdb_strerror(errno, buf, sizeof(buf)));
 129                 return -1;
 130         }
 131         return 0;
 132 } /* open_unix_sock */
 133
 134 /*
 135  * private variables
 136  */
 137
 138 /* the enum has to be sorted the same as the implementations array
 139  * to ensure that the type may be used as index into the array */
 140 enum {
 141         LISTENER_UNIXSOCK = 0,
 142 };
 143 static fe_listener_impl_t listener_impls[] = {
 144         { LISTENER_UNIXSOCK, "unix", open_unix_sock },
 145 };
 146
 147 /*
 148  * private helper functions
 149  */
 150
 151 static int
 152 get_type(const char *address)
 153 {
 154         char *sep;
 155         size_t len;
 156         size_t i;
 157
 158         sep = strchr(address, (int)':');
 159         if (! sep)
 160                 return -1;
 161
 162         assert(sep > address);
 163         len = (size_t)(sep - address);
 164
 165         for (i = 0; i < SDB_STATIC_ARRAY_LEN(listener_impls); ++i) {
 166                 fe_listener_impl_t *impl = listener_impls + i;
 167
 168                 if (!strncmp(address, impl->prefix, len)) {
 169                         assert(impl->type == (int)i);
 170                         return impl->type;
 171                 }
 172         }
 173         return -1;
 174 } /* get_type */
 175
 176 static void
 177 listener_destroy(listener_t *listener)
 178 {
 179         if (! listener)
 180                 return;
 181
 182         if (listener->sock_fd >= 0)
 183                 close(listener->sock_fd);
 184         listener->sock_fd = -1;
 185
 186         if (listener->address)
 187                 free(listener->address);
 188 } /* listener_destroy */
 189
 190 static listener_t *
 191 listener_create(sdb_fe_socket_t *sock, const char *address)
 192 {
 193         listener_t *listener;
 194         int type;
 195
 196         type = get_type(address);
 197         if (type < 0) {
 198                 sdb_log(SDB_LOG_ERR, "frontend: Unsupported address type specified "
 199                                 "in listen address '%s'", address);
 200                 return NULL;
 201         }
 202
 203         listener = realloc(sock->listeners,
 204                         sock->listeners_num * sizeof(*sock->listeners));
 205         if (! listener) {
 206                 char buf[1024];
 207                 sdb_log(SDB_LOG_ERR, "frontend: Failed to allocate memory: %s",
 208                                 sdb_strerror(errno, buf, sizeof(buf)));
 209                 return NULL;
 210         }
 211
 212         sock->listeners = listener;
 213         listener = sock->listeners + sock->listeners_num;
 214
 215         listener->sock_fd = -1;
 216         listener->address = strdup(address);
 217         if (! listener->address) {
 218                 char buf[1024];
 219                 sdb_log(SDB_LOG_ERR, "frontend: Failed to allocate memory: %s",
 220                                 sdb_strerror(errno, buf, sizeof(buf)));
 221                 listener_destroy(listener);
 222                 return NULL;
 223         }
 224         listener->type = type;
 225
 226         if (listener_impls[type].opener(listener)) {
 227                 /* prints error */
 228                 listener_destroy(listener);
 229                 return NULL;
 230         }
 231
 232         ++sock->listeners_num;
 233         return listener;
 234 } /* listener_create */
 235
 236 static int
 237 listener_listen(listener_t *listener)
 238 {
 239         assert(listener);
 240
 241         /* try to reopen */
 242         if (listener->sock_fd < 0)
 243                 if (listener_impls[listener->type].opener(listener))
 244                         return -1;
 245         assert(listener->sock_fd >= 0);
 246
 247         if (listen(listener->sock_fd, /* backlog = */ 32)) {
 248                 char buf[1024];
 249                 sdb_log(SDB_LOG_ERR, "frontend: Failed to listen on socket %s: %s",
 250                                 listener->address, sdb_strerror(errno, buf, sizeof(buf)));
 251                 return -1;
 252         }
 253         return 0;
 254 } /* listener_listen */
 255
 256 static void
 257 listener_close(listener_t *listener)
 258 {
 259         assert(listener);
 260
 261         if (listener->sock_fd < 0)
 262                 return;
 263
 264         close(listener->sock_fd);
 265         listener->sock_fd = -1;
 266 } /* listener_close */
 267
 268 static void
 269 socket_close(sdb_fe_socket_t *sock)
 270 {
 271         size_t i;
 272
 273         assert(sock);
 274         for (i = 0; i < sock->listeners_num; ++i)
 275                 listener_close(sock->listeners + i);
 276 } /* socket_close */
 277
 278 /*
 279  * private data types
 280  */
 281
 282 static int
 283 connection_init(sdb_object_t *obj, va_list ap)
 284 {
 285         connection_t *conn;
 286         int sock_fd;
 287         int sock_fl;
 288
 289         assert(obj);
 290         conn = &CONN(obj)->conn;
 291
 292         sock_fd = va_arg(ap, int);
 293
 294         conn->client_addr_len = sizeof(conn->client_addr);
 295         conn->fd = accept(sock_fd, (struct sockaddr *)&conn->client_addr,
 296                         &conn->client_addr_len);
 297
 298         if (conn->fd < 0) {
 299                 char buf[1024];
 300                 sdb_log(SDB_LOG_ERR, "frontend: Failed to accept remote "
 301                                 "connection: %s", sdb_strerror(errno,
 302                                         buf, sizeof(buf)));
 303                 return -1;
 304         }
 305
 306         if (conn->client_addr.ss_family != AF_UNIX) {
 307                 sdb_log(SDB_LOG_ERR, "frontend: Accepted connection using "
 308                                 "unexpected family type %d", conn->client_addr.ss_family);
 309                 return -1;
 310         }
 311
 312         sock_fl = fcntl(conn->fd, F_GETFL);
 313         if (fcntl(conn->fd, F_SETFL, sock_fl | O_NONBLOCK)) {
 314                 char buf[1024];
 315                 sdb_log(SDB_LOG_ERR, "frontend: Failed to switch connection conn#%i "
 316                                 "to non-blocking mode: %s", conn->fd,
 317                                 sdb_strerror(errno, buf, sizeof(buf)));
 318                 return -1;
 319         }
 320
 321         sdb_log(SDB_LOG_DEBUG, "frontend: Accepted connection on fd=%i",
 322                         conn->fd);
 323
 324         /* update the object name */
 325         snprintf(obj->name + strlen(CONN_FD_PREFIX),
 326                         strlen(CONN_FD_PLACEHOLDER), "%i", conn->fd);
 327         return 0;
 328 } /* connection_init */
 329
 330 static void
 331 connection_destroy(sdb_object_t *obj)
 332 {
 333         connection_t *conn;
 334
 335         assert(obj);
 336         conn = &CONN(obj)->conn;
 337
 338         sdb_log(SDB_LOG_DEBUG, "frontend: Closing connection on fd=%i", conn->fd);
 339         close(conn->fd);
 340         conn->fd = -1;
 341 } /* connection_destroy */
 342
 343 static sdb_type_t connection_type = {
 344         /* size = */ sizeof(connection_obj_t),
 345         /* init = */ connection_init,
 346         /* destroy = */ connection_destroy,
 347 };
 348
 349 /*
 350  * connection handler functions
 351  */
 352
 353 /* returns negative value on error, 0 on EOF, number of packets else */
 354 static int
 355 connection_read(int fd)
 356 {
 357         int n = 0;
 358
 359         while (42) {
 360                 int32_t cmd;
 361                 ssize_t status;
 362
 363                 errno = 0;
 364                 status = read(fd, &cmd, sizeof(cmd));
 365                 if (status < 0) {
 366                         if ((errno == EAGAIN) || (errno == EWOULDBLOCK))
 367                                 return n + 1;
 368                         return (int)status;
 369                 }
 370                 else if (! status) /* EOF */
 371                         return 0;
 372
 373                 /* XXX */
 374                 sdb_log(SDB_LOG_DEBUG, "frontend: read command %i from fd=%i",
 375                                 cmd, fd);
 376                 ++n;
 377         }
 378
 379         return n + 1;
 380 } /* connection_read */
 381
 382 static void *
 383 connection_handler(void *data)
 384 {
 385         sdb_fe_socket_t *sock = data;
 386
 387         assert(sock);
 388
 389         while (42) {
 390                 struct timespec timeout = { 0, 500000000 }; /* .5 seconds */
 391                 connection_obj_t *conn;
 392                 int status;
 393
 394                 errno = 0;
 395                 status = sdb_channel_select(sock->chan, /* read */ NULL, &conn,
 396                                 /* write */ NULL, NULL, &timeout);
 397                 if (status) {
 398                         char buf[1024];
 399
 400                         if (errno == ETIMEDOUT)
 401                                 continue;
 402                         if (errno == EBADF) /* channel shut down */
 403                                 break;
 404
 405                         sdb_log(SDB_LOG_ERR, "frontend: Failed to read from channel: %s",
 406                                         sdb_strerror(errno, buf, sizeof(buf)));
 407                         continue;
 408                 }
 409
 410                 status = connection_read(conn->conn.fd);
 411                 if (status <= 0) {
 412                         /* error or EOF -> close connection */
 413                         sdb_object_deref(SDB_OBJ(conn));
 414                 }
 415                 else {
 416                         if (sdb_llist_append(sock->open_connections, SDB_OBJ(conn))) {
 417                                 sdb_log(SDB_LOG_ERR, "frontend: Failed to re-append "
 418                                                 "connection %s to list of open connections",
 419                                                 SDB_OBJ(conn)->name);
 420                         }
 421
 422                         /* pass ownership back to list; or destroy in case of an error */
 423                         sdb_object_deref(SDB_OBJ(conn));
 424                 }
 425         }
 426         return NULL;
 427 } /* connection_handler */
 428
 429 static int
 430 connection_accept(sdb_fe_socket_t *sock, listener_t *listener)
 431 {
 432         sdb_object_t *obj;
 433
 434         /* the placeholder will be replaced with the accepted file
 435          * descriptor when initializing the object */
 436         obj = sdb_object_create(CONN_FD_PREFIX CONN_FD_PLACEHOLDER,
 437                         connection_type, listener->sock_fd);
 438         if (! obj)
 439                 return -1;
 440
 441         if (sdb_llist_append(sock->open_connections, obj)) {
 442                 sdb_log(SDB_LOG_ERR, "frontend: Failed to append "
 443                                 "connection %s to list of open connections",
 444                                 obj->name);
 445                 sdb_object_deref(obj);
 446                 return -1;
 447         }
 448
 449         /* hand ownership over to the list */
 450         sdb_object_deref(obj);
 451         return 0;
 452 } /* connection_accept */
 453
 454 static int
 455 socket_handle_incoming(sdb_fe_socket_t *sock,
 456                 fd_set *ready, fd_set *exceptions)
 457 {
 458         sdb_llist_iter_t *iter;
 459         size_t i;
 460
 461         for (i = 0; i < sock->listeners_num; ++i) {
 462                 listener_t *listener = sock->listeners + i;
 463                 if (FD_ISSET(listener->sock_fd, ready))
 464                         if (connection_accept(sock, listener))
 465                                 continue;
 466         }
 467
 468         iter = sdb_llist_get_iter(sock->open_connections);
 469         if (! iter) {
 470                 sdb_log(SDB_LOG_ERR, "frontend: Failed to acquire iterator "
 471                                 "for open connections");
 472                 return -1;
 473         }
 474
 475         while (sdb_llist_iter_has_next(iter)) {
 476                 sdb_object_t *obj = sdb_llist_iter_get_next(iter);
 477
 478                 if (FD_ISSET(CONN(obj)->conn.fd, exceptions))
 479                         sdb_log(SDB_LOG_INFO, "Exception on fd %d",
 480                                         CONN(obj)->conn.fd);
 481
 482                 if (FD_ISSET(CONN(obj)->conn.fd, ready)) {
 483                         sdb_llist_iter_remove_current(iter);
 484                         sdb_channel_write(sock->chan, &obj);
 485                 }
 486         }
 487         sdb_llist_iter_destroy(iter);
 488         return 0;
 489 } /* socket_handle_incoming */
 490
 491 /*
 492  * public API
 493  */
 494
 495 sdb_fe_socket_t *
 496 sdb_fe_sock_create(void)
 497 {
 498         sdb_fe_socket_t *sock;
 499
 500         sock = calloc(1, sizeof(*sock));
 501         if (! sock)
 502                 return NULL;
 503
 504         sock->open_connections = sdb_llist_create();
 505         if (! sock->open_connections) {
 506                 sdb_fe_sock_destroy(sock);
 507                 return NULL;
 508         }
 509         return sock;
 510 } /* sdb_fe_sock_create */
 511
 512 void
 513 sdb_fe_sock_destroy(sdb_fe_socket_t *sock)
 514 {
 515         size_t i;
 516
 517         if (! sock)
 518                 return;
 519
 520         for (i = 0; i < sock->listeners_num; ++i) {
 521                 listener_destroy(sock->listeners + i);
 522         }
 523         if (sock->listeners)
 524                 free(sock->listeners);
 525         sock->listeners = NULL;
 526
 527         sdb_llist_destroy(sock->open_connections);
 528         sock->open_connections = NULL;
 529         free(sock);
 530 } /* sdb_fe_sock_destroy */
 531
 532 int
 533 sdb_fe_sock_add_listener(sdb_fe_socket_t *sock, const char *address)
 534 {
 535         listener_t *listener;
 536
 537         if ((! sock) || (! address))
 538                 return -1;
 539
 540         listener = listener_create(sock, address);
 541         if (! listener)
 542                 return -1;
 543         return 0;
 544 } /* sdb_fe_sock_add_listener */
 545
 546 int
 547 sdb_fe_sock_listen_and_serve(sdb_fe_socket_t *sock, sdb_fe_loop_t *loop)
 548 {
 549         fd_set sockets;
 550         int max_listen_fd = 0;
 551         size_t i;
 552
 553         /* XXX: make the number of threads configurable */
 554         pthread_t handler_threads[5];
 555
 556         if ((! sock) || (! sock->listeners_num) || (! loop) || sock->chan)
 557                 return -1;
 558
 559         FD_ZERO(&sockets);
 560         for (i = 0; i < sock->listeners_num; ++i) {
 561                 listener_t *listener = sock->listeners + i;
 562
 563                 if (listener_listen(listener)) {
 564                         socket_close(sock);
 565                         return -1;
 566                 }
 567
 568                 FD_SET(listener->sock_fd, &sockets);
 569                 if (listener->sock_fd > max_listen_fd)
 570                         max_listen_fd = listener->sock_fd;
 571         }
 572
 573         sock->chan = sdb_channel_create(1024, sizeof(connection_obj_t *));
 574         if (! sock->chan) {
 575                 socket_close(sock);
 576                 return -1;
 577         }
 578
 579         memset(&handler_threads, 0, sizeof(handler_threads));
 580         /* XXX: error handling */
 581         for (i = 0; i < SDB_STATIC_ARRAY_LEN(handler_threads); ++i)
 582                 pthread_create(&handler_threads[i], /* attr = */ NULL,
 583                                 connection_handler, /* arg = */ sock);
 584
 585         while (loop->do_loop) {
 586                 struct timeval timeout = { 1, 0 }; /* one second */
 587                 sdb_llist_iter_t *iter;
 588
 589                 int max_fd = max_listen_fd;
 590                 fd_set ready;
 591                 fd_set exceptions;
 592                 int n;
 593
 594                 FD_ZERO(&ready);
 595                 FD_ZERO(&exceptions);
 596
 597                 ready = sockets;
 598
 599                 iter = sdb_llist_get_iter(sock->open_connections);
 600                 if (! iter) {
 601                         sdb_log(SDB_LOG_ERR, "frontend: Failed to acquire iterator "
 602                                         "for open connections");
 603                         break;
 604                 }
 605
 606                 while (sdb_llist_iter_has_next(iter)) {
 607                         sdb_object_t *obj = sdb_llist_iter_get_next(iter);
 608                         FD_SET(CONN(obj)->conn.fd, &ready);
 609                         FD_SET(CONN(obj)->conn.fd, &exceptions);
 610
 611                         if (CONN(obj)->conn.fd > max_fd)
 612                                 max_fd = CONN(obj)->conn.fd;
 613                 }
 614                 sdb_llist_iter_destroy(iter);
 615
 616                 errno = 0;
 617                 n = select(max_fd + 1, &ready, NULL, &exceptions, &timeout);
 618                 if (n < 0) {
 619                         char buf[1024];
 620
 621                         if (errno == EINTR)
 622                                 continue;
 623
 624                         sdb_log(SDB_LOG_ERR, "frontend: Failed to monitor sockets: %s",
 625                                         sdb_strerror(errno, buf, sizeof(buf)));
 626                         break;
 627                 }
 628                 else if (! n)
 629                         continue;
 630
 631                 /* handle new and open connections */
 632                 if (socket_handle_incoming(sock, &ready, &exceptions))
 633                         break;
 634         }
 635
 636         socket_close(sock);
 637
 638         sdb_log(SDB_LOG_INFO, "frontend: Waiting for connection handler threads "
 639                         "to terminate");
 640         if (! sdb_channel_shutdown(sock->chan))
 641                 for (i = 0; i < SDB_STATIC_ARRAY_LEN(handler_threads); ++i)
 642                         pthread_join(handler_threads[i], NULL);
 643         /* else: we tried our best; let the operating system clean up */
 644
 645         sdb_channel_destroy(sock->chan);
 646         sock->chan = NULL;
 647         return 0;
 648 } /* sdb_fe_sock_listen_and_server */
 649
 650 /* vim: set tw=78 sw=4 ts=4 noexpandtab : */
 651