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
 185         if (listener->address)
 186                 free(listener->address);
 187 } /* listener_destroy */
 188
 189 static listener_t *
 190 listener_create(sdb_fe_socket_t *sock, const char *address)
 191 {
 192         listener_t *listener;
 193         int type;
 194
 195         type = get_type(address);
 196         if (type < 0) {
 197                 sdb_log(SDB_LOG_ERR, "frontend: Unsupported address type specified "
 198                                 "in listen address '%s'", address);
 199                 return NULL;
 200         }
 201
 202         listener = realloc(sock->listeners,
 203                         sock->listeners_num * sizeof(*sock->listeners));
 204         if (! listener) {
 205                 char buf[1024];
 206                 sdb_log(SDB_LOG_ERR, "frontend: Failed to allocate memory: %s",
 207                                 sdb_strerror(errno, buf, sizeof(buf)));
 208                 return NULL;
 209         }
 210
 211         sock->listeners = listener;
 212         listener = sock->listeners + sock->listeners_num;
 213
 214         listener->sock_fd = -1;
 215         listener->address = strdup(address);
 216         if (! listener->address) {
 217                 char buf[1024];
 218                 sdb_log(SDB_LOG_ERR, "frontend: Failed to allocate memory: %s",
 219                                 sdb_strerror(errno, buf, sizeof(buf)));
 220                 listener_destroy(listener);
 221                 return NULL;
 222         }
 223         listener->type = type;
 224
 225         if (listener_impls[type].opener(listener)) {
 226                 /* prints error */
 227                 listener_destroy(listener);
 228                 return NULL;
 229         }
 230
 231         ++sock->listeners_num;
 232         return listener;
 233 } /* listener_create */
 234
 235 /*
 236  * private data types
 237  */
 238
 239 static int
 240 connection_init(sdb_object_t *obj, va_list ap)
 241 {
 242         connection_t *conn;
 243         int sock_fd;
 244         int sock_fl;
 245
 246         assert(obj);
 247         conn = &CONN(obj)->conn;
 248
 249         sock_fd = va_arg(ap, int);
 250
 251         conn->client_addr_len = sizeof(conn->client_addr);
 252         conn->fd = accept(sock_fd, (struct sockaddr *)&conn->client_addr,
 253                         &conn->client_addr_len);
 254
 255         if (conn->fd < 0) {
 256                 char buf[1024];
 257                 sdb_log(SDB_LOG_ERR, "frontend: Failed to accept remote "
 258                                 "connection: %s", sdb_strerror(errno,
 259                                         buf, sizeof(buf)));
 260                 return -1;
 261         }
 262
 263         if (conn->client_addr.ss_family != AF_UNIX) {
 264                 sdb_log(SDB_LOG_ERR, "frontend: Accepted connection using "
 265                                 "unexpected family type %d", conn->client_addr.ss_family);
 266                 return -1;
 267         }
 268
 269         sock_fl = fcntl(conn->fd, F_GETFL);
 270         if (fcntl(conn->fd, F_SETFL, sock_fl | O_NONBLOCK)) {
 271                 char buf[1024];
 272                 sdb_log(SDB_LOG_ERR, "frontend: Failed to switch connection conn#%i "
 273                                 "to non-blocking mode: %s", conn->fd,
 274                                 sdb_strerror(errno, buf, sizeof(buf)));
 275                 return -1;
 276         }
 277
 278         sdb_log(SDB_LOG_DEBUG, "frontend: Accepted connection on fd=%i",
 279                         conn->fd);
 280
 281         /* update the object name */
 282         snprintf(obj->name + strlen(CONN_FD_PREFIX),
 283                         strlen(CONN_FD_PLACEHOLDER), "%i", conn->fd);
 284         return 0;
 285 } /* connection_init */
 286
 287 static void
 288 connection_destroy(sdb_object_t *obj)
 289 {
 290         connection_t *conn;
 291
 292         assert(obj);
 293         conn = &CONN(obj)->conn;
 294
 295         sdb_log(SDB_LOG_DEBUG, "frontend: Closing connection on fd=%i", conn->fd);
 296         close(conn->fd);
 297         conn->fd = -1;
 298 } /* connection_destroy */
 299
 300 static sdb_type_t connection_type = {
 301         /* size = */ sizeof(connection_obj_t),
 302         /* init = */ connection_init,
 303         /* destroy = */ connection_destroy,
 304 };
 305
 306 /*
 307  * connection handler functions
 308  */
 309
 310 /* returns negative value on error, 0 on EOF, number of packets else */
 311 static int
 312 connection_read(int fd)
 313 {
 314         int n = 0;
 315
 316         while (42) {
 317                 int32_t cmd;
 318                 ssize_t status;
 319
 320                 errno = 0;
 321                 status = read(fd, &cmd, sizeof(cmd));
 322                 if (status < 0) {
 323                         if ((errno == EAGAIN) || (errno == EWOULDBLOCK))
 324                                 return n + 1;
 325                         return (int)status;
 326                 }
 327                 else if (! status) /* EOF */
 328                         return 0;
 329
 330                 /* XXX */
 331                 sdb_log(SDB_LOG_DEBUG, "frontend: read command %i from fd=%i",
 332                                 cmd, fd);
 333                 ++n;
 334         }
 335
 336         return n + 1;
 337 } /* connection_read */
 338
 339 static void *
 340 connection_handler(void *data)
 341 {
 342         sdb_fe_socket_t *sock = data;
 343
 344         assert(sock);
 345
 346         while (42) {
 347                 struct timespec timeout = { 0, 500000000 }; /* .5 seconds */
 348                 connection_obj_t *conn;
 349                 int status;
 350
 351                 errno = 0;
 352                 status = sdb_channel_select(sock->chan, /* read */ NULL, &conn,
 353                                 /* write */ NULL, NULL, &timeout);
 354                 if (status) {
 355                         char buf[1024];
 356
 357                         if (errno == ETIMEDOUT)
 358                                 continue;
 359                         if (errno == EBADF) /* channel shut down */
 360                                 break;
 361
 362                         sdb_log(SDB_LOG_ERR, "frontend: Failed to read from channel: %s",
 363                                         sdb_strerror(errno, buf, sizeof(buf)));
 364                         continue;
 365                 }
 366
 367                 status = connection_read(conn->conn.fd);
 368                 if (status <= 0) {
 369                         /* error or EOF → close connection */
 370                         sdb_object_deref(SDB_OBJ(conn));
 371                 }
 372                 else {
 373                         if (sdb_llist_append(sock->open_connections, SDB_OBJ(conn))) {
 374                                 sdb_log(SDB_LOG_ERR, "frontend: Failed to re-append "
 375                                                 "connection %s to list of open connections",
 376                                                 SDB_OBJ(conn)->name);
 377                         }
 378
 379                         /* pass ownership back to list; or destroy in case of an error */
 380                         sdb_object_deref(SDB_OBJ(conn));
 381                 }
 382         }
 383         return NULL;
 384 } /* connection_handler */
 385
 386 static int
 387 connection_accept(sdb_fe_socket_t *sock, listener_t *listener)
 388 {
 389         sdb_object_t *obj;
 390
 391         /* the placeholder will be replaced with the accepted file
 392          * descriptor when initializing the object */
 393         obj = sdb_object_create(CONN_FD_PREFIX CONN_FD_PLACEHOLDER,
 394                         connection_type, listener->sock_fd);
 395         if (! obj)
 396                 return -1;
 397
 398         if (sdb_llist_append(sock->open_connections, obj)) {
 399                 sdb_log(SDB_LOG_ERR, "frontend: Failed to append "
 400                                 "connection %s to list of open connections",
 401                                 obj->name);
 402                 sdb_object_deref(obj);
 403                 return -1;
 404         }
 405
 406         /* hand ownership over to the list */
 407         sdb_object_deref(obj);
 408         return 0;
 409 } /* connection_accept */
 410
 411 /*
 412  * public API
 413  */
 414
 415 sdb_fe_socket_t *
 416 sdb_fe_sock_create(void)
 417 {
 418         sdb_fe_socket_t *sock;
 419
 420         sock = calloc(1, sizeof(*sock));
 421         if (! sock)
 422                 return NULL;
 423
 424         sock->open_connections = sdb_llist_create();
 425         if (! sock->open_connections) {
 426                 sdb_fe_sock_destroy(sock);
 427                 return NULL;
 428         }
 429         return sock;
 430 } /* sdb_fe_sock_create */
 431
 432 void
 433 sdb_fe_sock_destroy(sdb_fe_socket_t *sock)
 434 {
 435         size_t i;
 436
 437         if (! sock)
 438                 return;
 439
 440         for (i = 0; i < sock->listeners_num; ++i) {
 441                 listener_destroy(sock->listeners + i);
 442         }
 443         if (sock->listeners)
 444                 free(sock->listeners);
 445         sock->listeners = NULL;
 446
 447         sdb_llist_destroy(sock->open_connections);
 448         sock->open_connections = NULL;
 449         free(sock);
 450 } /* sdb_fe_sock_destroy */
 451
 452 int
 453 sdb_fe_sock_add_listener(sdb_fe_socket_t *sock, const char *address)
 454 {
 455         listener_t *listener;
 456
 457         if ((! sock) || (! address))
 458                 return -1;
 459
 460         listener = listener_create(sock, address);
 461         if (! listener)
 462                 return -1;
 463         return 0;
 464 } /* sdb_fe_sock_add_listener */
 465
 466 int
 467 sdb_fe_sock_listen_and_serve(sdb_fe_socket_t *sock, sdb_fe_loop_t *loop)
 468 {
 469         fd_set sockets;
 470         int max_listen_fd = 0;
 471         size_t i;
 472
 473         /* XXX: make the number of threads configurable */
 474         pthread_t handler_threads[5];
 475
 476         if ((! sock) || (! sock->listeners_num) || (! loop))
 477                 return -1;
 478
 479         FD_ZERO(&sockets);
 480
 481         for (i = 0; i < sock->listeners_num; ++i) {
 482                 listener_t *listener = sock->listeners + i;
 483
 484                 if (listen(listener->sock_fd, /* backlog = */ 32)) {
 485                         char buf[1024];
 486                         sdb_log(SDB_LOG_ERR, "frontend: Failed to listen on socket %s: %s",
 487                                         listener->address, sdb_strerror(errno, buf, sizeof(buf)));
 488                         return -1;
 489                 }
 490
 491                 FD_SET(listener->sock_fd, &sockets);
 492                 if (listener->sock_fd > max_listen_fd)
 493                         max_listen_fd = listener->sock_fd;
 494         }
 495
 496         sock->chan = sdb_channel_create(1024, sizeof(connection_obj_t *));
 497         if (! sock->chan)
 498                 return -1;
 499
 500         memset(&handler_threads, 0, sizeof(handler_threads));
 501         /* XXX: error handling */
 502         for (i = 0; i < SDB_STATIC_ARRAY_LEN(handler_threads); ++i)
 503                 pthread_create(&handler_threads[i], /* attr = */ NULL,
 504                                 connection_handler, /* arg = */ sock);
 505
 506         while (loop->do_loop) {
 507                 fd_set ready;
 508                 fd_set exceptions;
 509                 int max_fd;
 510                 int n;
 511
 512                 struct timeval timeout = { 1, 0 }; /* one second */
 513                 sdb_llist_iter_t *iter;
 514
 515                 FD_ZERO(&ready);
 516                 FD_ZERO(&exceptions);
 517
 518                 ready = sockets;
 519
 520                 max_fd = max_listen_fd;
 521
 522                 iter = sdb_llist_get_iter(sock->open_connections);
 523                 if (! iter) {
 524                         sdb_log(SDB_LOG_ERR, "frontend: Failed to acquire iterator "
 525                                         "for open connections");
 526                         return -1;
 527                 }
 528
 529                 while (sdb_llist_iter_has_next(iter)) {
 530                         sdb_object_t *obj = sdb_llist_iter_get_next(iter);
 531                         FD_SET(CONN(obj)->conn.fd, &ready);
 532                         FD_SET(CONN(obj)->conn.fd, &exceptions);
 533
 534                         if (CONN(obj)->conn.fd > max_fd)
 535                                 max_fd = CONN(obj)->conn.fd;
 536                 }
 537                 sdb_llist_iter_destroy(iter);
 538
 539                 errno = 0;
 540                 n = select(max_fd + 1, &ready, NULL, &exceptions, &timeout);
 541                 if (n < 0) {
 542                         char buf[1024];
 543
 544                         if (errno == EINTR)
 545                                 continue;
 546
 547                         sdb_log(SDB_LOG_ERR, "frontend: Failed to monitor sockets: %s",
 548                                         sdb_strerror(errno, buf, sizeof(buf)));
 549                         return -1;
 550                 }
 551
 552                 if (! n)
 553                         continue;
 554
 555                 for (i = 0; i < sock->listeners_num; ++i) {
 556                         listener_t *listener = sock->listeners + i;
 557                         if (FD_ISSET(listener->sock_fd, &ready))
 558                                 if (connection_accept(sock, listener))
 559                                         continue;
 560                 }
 561
 562                 iter = sdb_llist_get_iter(sock->open_connections);
 563                 if (! iter) {
 564                         sdb_log(SDB_LOG_ERR, "frontend: Failed to acquire iterator "
 565                                         "for open connections");
 566                         return -1;
 567                 }
 568
 569                 while (sdb_llist_iter_has_next(iter)) {
 570                         sdb_object_t *obj = sdb_llist_iter_get_next(iter);
 571
 572                         if (FD_ISSET(CONN(obj)->conn.fd, &exceptions))
 573                                 sdb_log(SDB_LOG_INFO, "Exception on fd %d",
 574                                                 CONN(obj)->conn.fd);
 575
 576                         if (FD_ISSET(CONN(obj)->conn.fd, &ready)) {
 577                                 sdb_llist_iter_remove_current(iter);
 578                                 sdb_channel_write(sock->chan, &obj);
 579                         }
 580                 }
 581                 sdb_llist_iter_destroy(iter);
 582         }
 583
 584         sdb_log(SDB_LOG_INFO, "frontend: Waiting for connection handler threads "
 585                         "to terminate");
 586         if (! sdb_channel_shutdown(sock->chan))
 587                 for (i = 0; i < SDB_STATIC_ARRAY_LEN(handler_threads); ++i)
 588                         pthread_join(handler_threads[i], NULL);
 589         /* else: we tried our best; let the operating system clean up */
 590         return 0;
 591 } /* sdb_fe_sock_listen_and_server */
 592
 593 /* vim: set tw=78 sw=4 ts=4 noexpandtab : */
 594