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         if (listen(listener->sock_fd, /* backlog = */ 32)) {
 242                 char buf[1024];
 243                 sdb_log(SDB_LOG_ERR, "frontend: Failed to listen on socket %s: %s",
 244                                 listener->address, sdb_strerror(errno, buf, sizeof(buf)));
 245                 return -1;
 246         }
 247         return 0;
 248 } /* listener_listen */
 249
 250 static void
 251 listener_close(listener_t *listener)
 252 {
 253         assert(listener);
 254
 255         if (listener->sock_fd < 0)
 256                 return;
 257
 258         close(listener->sock_fd);
 259         listener->sock_fd = -1;
 260 } /* listener_close */
 261
 262 /*
 263  * private data types
 264  */
 265
 266 static int
 267 connection_init(sdb_object_t *obj, va_list ap)
 268 {
 269         connection_t *conn;
 270         int sock_fd;
 271         int sock_fl;
 272
 273         assert(obj);
 274         conn = &CONN(obj)->conn;
 275
 276         sock_fd = va_arg(ap, int);
 277
 278         conn->client_addr_len = sizeof(conn->client_addr);
 279         conn->fd = accept(sock_fd, (struct sockaddr *)&conn->client_addr,
 280                         &conn->client_addr_len);
 281
 282         if (conn->fd < 0) {
 283                 char buf[1024];
 284                 sdb_log(SDB_LOG_ERR, "frontend: Failed to accept remote "
 285                                 "connection: %s", sdb_strerror(errno,
 286                                         buf, sizeof(buf)));
 287                 return -1;
 288         }
 289
 290         if (conn->client_addr.ss_family != AF_UNIX) {
 291                 sdb_log(SDB_LOG_ERR, "frontend: Accepted connection using "
 292                                 "unexpected family type %d", conn->client_addr.ss_family);
 293                 return -1;
 294         }
 295
 296         sock_fl = fcntl(conn->fd, F_GETFL);
 297         if (fcntl(conn->fd, F_SETFL, sock_fl | O_NONBLOCK)) {
 298                 char buf[1024];
 299                 sdb_log(SDB_LOG_ERR, "frontend: Failed to switch connection conn#%i "
 300                                 "to non-blocking mode: %s", conn->fd,
 301                                 sdb_strerror(errno, buf, sizeof(buf)));
 302                 return -1;
 303         }
 304
 305         sdb_log(SDB_LOG_DEBUG, "frontend: Accepted connection on fd=%i",
 306                         conn->fd);
 307
 308         /* update the object name */
 309         snprintf(obj->name + strlen(CONN_FD_PREFIX),
 310                         strlen(CONN_FD_PLACEHOLDER), "%i", conn->fd);
 311         return 0;
 312 } /* connection_init */
 313
 314 static void
 315 connection_destroy(sdb_object_t *obj)
 316 {
 317         connection_t *conn;
 318
 319         assert(obj);
 320         conn = &CONN(obj)->conn;
 321
 322         sdb_log(SDB_LOG_DEBUG, "frontend: Closing connection on fd=%i", conn->fd);
 323         close(conn->fd);
 324         conn->fd = -1;
 325 } /* connection_destroy */
 326
 327 static sdb_type_t connection_type = {
 328         /* size = */ sizeof(connection_obj_t),
 329         /* init = */ connection_init,
 330         /* destroy = */ connection_destroy,
 331 };
 332
 333 /*
 334  * connection handler functions
 335  */
 336
 337 /* returns negative value on error, 0 on EOF, number of packets else */
 338 static int
 339 connection_read(int fd)
 340 {
 341         int n = 0;
 342
 343         while (42) {
 344                 int32_t cmd;
 345                 ssize_t status;
 346
 347                 errno = 0;
 348                 status = read(fd, &cmd, sizeof(cmd));
 349                 if (status < 0) {
 350                         if ((errno == EAGAIN) || (errno == EWOULDBLOCK))
 351                                 return n + 1;
 352                         return (int)status;
 353                 }
 354                 else if (! status) /* EOF */
 355                         return 0;
 356
 357                 /* XXX */
 358                 sdb_log(SDB_LOG_DEBUG, "frontend: read command %i from fd=%i",
 359                                 cmd, fd);
 360                 ++n;
 361         }
 362
 363         return n + 1;
 364 } /* connection_read */
 365
 366 static void *
 367 connection_handler(void *data)
 368 {
 369         sdb_fe_socket_t *sock = data;
 370
 371         assert(sock);
 372
 373         while (42) {
 374                 struct timespec timeout = { 0, 500000000 }; /* .5 seconds */
 375                 connection_obj_t *conn;
 376                 int status;
 377
 378                 errno = 0;
 379                 status = sdb_channel_select(sock->chan, /* read */ NULL, &conn,
 380                                 /* write */ NULL, NULL, &timeout);
 381                 if (status) {
 382                         char buf[1024];
 383
 384                         if (errno == ETIMEDOUT)
 385                                 continue;
 386                         if (errno == EBADF) /* channel shut down */
 387                                 break;
 388
 389                         sdb_log(SDB_LOG_ERR, "frontend: Failed to read from channel: %s",
 390                                         sdb_strerror(errno, buf, sizeof(buf)));
 391                         continue;
 392                 }
 393
 394                 status = connection_read(conn->conn.fd);
 395                 if (status <= 0) {
 396                         /* error or EOF -> close connection */
 397                         sdb_object_deref(SDB_OBJ(conn));
 398                 }
 399                 else {
 400                         if (sdb_llist_append(sock->open_connections, SDB_OBJ(conn))) {
 401                                 sdb_log(SDB_LOG_ERR, "frontend: Failed to re-append "
 402                                                 "connection %s to list of open connections",
 403                                                 SDB_OBJ(conn)->name);
 404                         }
 405
 406                         /* pass ownership back to list; or destroy in case of an error */
 407                         sdb_object_deref(SDB_OBJ(conn));
 408                 }
 409         }
 410         return NULL;
 411 } /* connection_handler */
 412
 413 static int
 414 connection_accept(sdb_fe_socket_t *sock, listener_t *listener)
 415 {
 416         sdb_object_t *obj;
 417
 418         /* the placeholder will be replaced with the accepted file
 419          * descriptor when initializing the object */
 420         obj = sdb_object_create(CONN_FD_PREFIX CONN_FD_PLACEHOLDER,
 421                         connection_type, listener->sock_fd);
 422         if (! obj)
 423                 return -1;
 424
 425         if (sdb_llist_append(sock->open_connections, obj)) {
 426                 sdb_log(SDB_LOG_ERR, "frontend: Failed to append "
 427                                 "connection %s to list of open connections",
 428                                 obj->name);
 429                 sdb_object_deref(obj);
 430                 return -1;
 431         }
 432
 433         /* hand ownership over to the list */
 434         sdb_object_deref(obj);
 435         return 0;
 436 } /* connection_accept */
 437
 438 /*
 439  * public API
 440  */
 441
 442 sdb_fe_socket_t *
 443 sdb_fe_sock_create(void)
 444 {
 445         sdb_fe_socket_t *sock;
 446
 447         sock = calloc(1, sizeof(*sock));
 448         if (! sock)
 449                 return NULL;
 450
 451         sock->open_connections = sdb_llist_create();
 452         if (! sock->open_connections) {
 453                 sdb_fe_sock_destroy(sock);
 454                 return NULL;
 455         }
 456         return sock;
 457 } /* sdb_fe_sock_create */
 458
 459 void
 460 sdb_fe_sock_destroy(sdb_fe_socket_t *sock)
 461 {
 462         size_t i;
 463
 464         if (! sock)
 465                 return;
 466
 467         for (i = 0; i < sock->listeners_num; ++i) {
 468                 listener_destroy(sock->listeners + i);
 469         }
 470         if (sock->listeners)
 471                 free(sock->listeners);
 472         sock->listeners = NULL;
 473
 474         sdb_llist_destroy(sock->open_connections);
 475         sock->open_connections = NULL;
 476         free(sock);
 477 } /* sdb_fe_sock_destroy */
 478
 479 int
 480 sdb_fe_sock_add_listener(sdb_fe_socket_t *sock, const char *address)
 481 {
 482         listener_t *listener;
 483
 484         if ((! sock) || (! address))
 485                 return -1;
 486
 487         listener = listener_create(sock, address);
 488         if (! listener)
 489                 return -1;
 490         return 0;
 491 } /* sdb_fe_sock_add_listener */
 492
 493 int
 494 sdb_fe_sock_listen_and_serve(sdb_fe_socket_t *sock, sdb_fe_loop_t *loop)
 495 {
 496         fd_set sockets;
 497         int max_listen_fd = 0;
 498         size_t i;
 499
 500         /* XXX: make the number of threads configurable */
 501         pthread_t handler_threads[5];
 502
 503         if ((! sock) || (! sock->listeners_num) || (! loop))
 504                 return -1;
 505
 506         if (sock->chan)
 507                 return -1;
 508
 509         FD_ZERO(&sockets);
 510
 511         for (i = 0; i < sock->listeners_num; ++i) {
 512                 listener_t *listener = sock->listeners + i;
 513
 514                 if (listener_listen(listener))
 515                         return -1;
 516
 517                 FD_SET(listener->sock_fd, &sockets);
 518                 if (listener->sock_fd > max_listen_fd)
 519                         max_listen_fd = listener->sock_fd;
 520         }
 521
 522         sock->chan = sdb_channel_create(1024, sizeof(connection_obj_t *));
 523         if (! sock->chan)
 524                 return -1;
 525
 526         memset(&handler_threads, 0, sizeof(handler_threads));
 527         /* XXX: error handling */
 528         for (i = 0; i < SDB_STATIC_ARRAY_LEN(handler_threads); ++i)
 529                 pthread_create(&handler_threads[i], /* attr = */ NULL,
 530                                 connection_handler, /* arg = */ sock);
 531
 532         while (loop->do_loop) {
 533                 fd_set ready;
 534                 fd_set exceptions;
 535                 int max_fd;
 536                 int n;
 537
 538                 struct timeval timeout = { 1, 0 }; /* one second */
 539                 sdb_llist_iter_t *iter;
 540
 541                 FD_ZERO(&ready);
 542                 FD_ZERO(&exceptions);
 543
 544                 ready = sockets;
 545
 546                 max_fd = max_listen_fd;
 547
 548                 iter = sdb_llist_get_iter(sock->open_connections);
 549                 if (! iter) {
 550                         sdb_log(SDB_LOG_ERR, "frontend: Failed to acquire iterator "
 551                                         "for open connections");
 552                         break;
 553                 }
 554
 555                 while (sdb_llist_iter_has_next(iter)) {
 556                         sdb_object_t *obj = sdb_llist_iter_get_next(iter);
 557                         FD_SET(CONN(obj)->conn.fd, &ready);
 558                         FD_SET(CONN(obj)->conn.fd, &exceptions);
 559
 560                         if (CONN(obj)->conn.fd > max_fd)
 561                                 max_fd = CONN(obj)->conn.fd;
 562                 }
 563                 sdb_llist_iter_destroy(iter);
 564
 565                 errno = 0;
 566                 n = select(max_fd + 1, &ready, NULL, &exceptions, &timeout);
 567                 if (n < 0) {
 568                         char buf[1024];
 569
 570                         if (errno == EINTR)
 571                                 continue;
 572
 573                         sdb_log(SDB_LOG_ERR, "frontend: Failed to monitor sockets: %s",
 574                                         sdb_strerror(errno, buf, sizeof(buf)));
 575                         break;
 576                 }
 577
 578                 if (! n)
 579                         continue;
 580
 581                 for (i = 0; i < sock->listeners_num; ++i) {
 582                         listener_t *listener = sock->listeners + i;
 583                         if (FD_ISSET(listener->sock_fd, &ready))
 584                                 if (connection_accept(sock, listener))
 585                                         continue;
 586                 }
 587
 588                 iter = sdb_llist_get_iter(sock->open_connections);
 589                 if (! iter) {
 590                         sdb_log(SDB_LOG_ERR, "frontend: Failed to acquire iterator "
 591                                         "for open connections");
 592                         break;
 593                 }
 594
 595                 while (sdb_llist_iter_has_next(iter)) {
 596                         sdb_object_t *obj = sdb_llist_iter_get_next(iter);
 597
 598                         if (FD_ISSET(CONN(obj)->conn.fd, &exceptions))
 599                                 sdb_log(SDB_LOG_INFO, "Exception on fd %d",
 600                                                 CONN(obj)->conn.fd);
 601
 602                         if (FD_ISSET(CONN(obj)->conn.fd, &ready)) {
 603                                 sdb_llist_iter_remove_current(iter);
 604                                 sdb_channel_write(sock->chan, &obj);
 605                         }
 606                 }
 607                 sdb_llist_iter_destroy(iter);
 608         }
 609
 610         for (i = 0; i < sock->listeners_num; ++i)
 611                 listener_close(sock->listeners + i);
 612
 613         sdb_log(SDB_LOG_INFO, "frontend: Waiting for connection handler threads "
 614                         "to terminate");
 615         if (! sdb_channel_shutdown(sock->chan))
 616                 for (i = 0; i < SDB_STATIC_ARRAY_LEN(handler_threads); ++i)
 617                         pthread_join(handler_threads[i], NULL);
 618         /* else: we tried our best; let the operating system clean up */
 619
 620         sdb_channel_destroy(sock->chan);
 621         sock->chan = NULL;
 622         return 0;
 623 } /* sdb_fe_sock_listen_and_server */
 624
 625 /* vim: set tw=78 sw=4 ts=4 noexpandtab : */
 626