src/frontend/connection.c

   1 /*
   2  * SysDB - src/frontend/connection.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 #ifdef HAVE_CONFIG_H
  29 #       include "config.h"
  30 #endif
  31
  32 #include "sysdb.h"
  33 #include "core/object.h"
  34 #include "core/plugin.h"
  35 #include "frontend/connection-private.h"
  36 #include "utils/error.h"
  37 #include "utils/strbuf.h"
  38 #include "utils/proto.h"
  39 #include "utils/os.h"
  40
  41 #include <assert.h>
  42 #include <errno.h>
  43
  44 #include <arpa/inet.h>
  45 #include <fcntl.h>
  46
  47 #include <stdlib.h>
  48 #include <string.h>
  49
  50 #include <sys/socket.h>
  51 #include <sys/types.h>
  52 #include <sys/param.h>
  53
  54 #ifdef HAVE_UCRED_H
  55 #       include <ucred.h>
  56 #endif
  57 #ifdef HAVE_SYS_UCRED_H
  58 #       include <sys/ucred.h>
  59 #endif
  60
  61 #include <pwd.h>
  62
  63 #include <pthread.h>
  64
  65 /*
  66  * private variables
  67  */
  68
  69 static pthread_key_t conn_ctx_key;
  70 static bool          conn_ctx_key_initialized = 0;
  71
  72 /*
  73  * private types
  74  */
  75
  76 /* name of connection objects */
  77 #define CONN_FD_PREFIX "conn#"
  78 #define CONN_FD_PLACEHOLDER "XXXXXXX"
  79
  80 /* XXX: only supports UNIX sockets so far */
  81 static char *
  82 peer(int sockfd)
  83 {
  84         uid_t uid;
  85
  86         struct passwd pw_entry;
  87         struct passwd *result = NULL;
  88         char buf[1024];
  89
  90 #ifdef SO_PEERCRED
  91         struct ucred cred;
  92         socklen_t len = sizeof(cred);
  93
  94         if (getsockopt(sockfd, SOL_SOCKET, SO_PEERCRED, &cred, &len)
  95                         || (len != sizeof(cred)))
  96                 return NULL;
  97         uid = cred.uid;
  98 #else /* SO_PEERCRED */
  99         errno = ENOSYS;
 100         return NULL;
 101 #endif
 102
 103         memset(&pw_entry, 0, sizeof(pw_entry));
 104         if (getpwuid_r(uid, &pw_entry, buf, sizeof(buf), &result)
 105                         || (! result))
 106                 return NULL;
 107         return strdup(result->pw_name);
 108 } /* peer */
 109
 110 static int
 111 connection_init(sdb_object_t *obj, va_list ap)
 112 {
 113         sdb_conn_t *conn;
 114         int sock_fd;
 115         int sock_fl;
 116
 117         assert(obj);
 118         conn = CONN(obj);
 119
 120         sock_fd = va_arg(ap, int);
 121
 122         conn->buf = sdb_strbuf_create(/* size = */ 128);
 123         if (! conn->buf) {
 124                 sdb_log(SDB_LOG_ERR, "frontend: Failed to allocate a read buffer "
 125                                 "for a new connection");
 126                 return -1;
 127         }
 128         conn->errbuf = sdb_strbuf_create(0);
 129         if (! conn->errbuf) {
 130                 sdb_log(SDB_LOG_ERR, "frontend: Failed to allocate an error buffer "
 131                                 "for a new connection");
 132                 return -1;
 133         }
 134
 135         conn->client_addr_len = sizeof(conn->client_addr);
 136         conn->fd = accept(sock_fd, (struct sockaddr *)&conn->client_addr,
 137                         &conn->client_addr_len);
 138
 139         if (conn->fd < 0) {
 140                 char buf[1024];
 141                 sdb_log(SDB_LOG_ERR, "frontend: Failed to accept remote "
 142                                 "connection: %s", sdb_strerror(errno,
 143                                         buf, sizeof(buf)));
 144                 return -1;
 145         }
 146
 147         if (conn->client_addr.ss_family != AF_UNIX) {
 148                 sdb_log(SDB_LOG_ERR, "frontend: Accepted connection using "
 149                                 "unexpected family type %d", conn->client_addr.ss_family);
 150                 return -1;
 151         }
 152
 153         sock_fl = fcntl(conn->fd, F_GETFL);
 154         if (fcntl(conn->fd, F_SETFL, sock_fl | O_NONBLOCK)) {
 155                 char buf[1024];
 156                 sdb_log(SDB_LOG_ERR, "frontend: Failed to switch connection conn#%i "
 157                                 "to non-blocking mode: %s", conn->fd,
 158                                 sdb_strerror(errno, buf, sizeof(buf)));
 159                 return -1;
 160         }
 161
 162         conn->username = peer(conn->fd);
 163         if (! conn->username) {
 164                 char buf[1024];
 165                 sdb_log(SDB_LOG_ERR, "frontend: Failed to retrieve peer for "
 166                                 "connection conn#%i: %s", conn->fd,
 167                                 sdb_strerror(errno, buf, sizeof(buf)));
 168                 return -1;
 169         }
 170         conn->ready = 0;
 171
 172         sdb_log(SDB_LOG_DEBUG, "frontend: Accepted connection on fd=%i",
 173                         conn->fd);
 174
 175         conn->cmd = SDB_CONNECTION_IDLE;
 176         conn->cmd_len = 0;
 177         conn->skip_len = 0;
 178
 179         /* update the object name */
 180         snprintf(obj->name + strlen(CONN_FD_PREFIX),
 181                         strlen(CONN_FD_PLACEHOLDER), "%i", conn->fd);
 182         return 0;
 183 } /* connection_init */
 184
 185 static void
 186 connection_destroy(sdb_object_t *obj)
 187 {
 188         sdb_conn_t *conn;
 189         size_t len;
 190
 191         assert(obj);
 192         conn = CONN(obj);
 193
 194         conn->ready = 0;
 195
 196         if (conn->buf) {
 197                 len = sdb_strbuf_len(conn->buf);
 198                 if (len)
 199                         sdb_log(SDB_LOG_INFO, "frontend: Discarding incomplete command "
 200                                         "(%zu byte%s left in buffer)", len, len == 1 ? "" : "s");
 201         }
 202
 203         sdb_log(SDB_LOG_DEBUG, "frontend: Closing connection %s", obj->name);
 204         sdb_connection_close(conn);
 205
 206         if (conn->username)
 207                 free(conn->username);
 208         conn->username = NULL;
 209
 210         sdb_strbuf_destroy(conn->buf);
 211         conn->buf = NULL;
 212         sdb_strbuf_destroy(conn->errbuf);
 213         conn->errbuf = NULL;
 214 } /* connection_destroy */
 215
 216 static sdb_type_t connection_type = {
 217         /* size = */ sizeof(sdb_conn_t),
 218         /* init = */ connection_init,
 219         /* destroy = */ connection_destroy,
 220 };
 221
 222 /*
 223  * private helper functions
 224  */
 225
 226 static void
 227 sdb_conn_ctx_destructor(void *c)
 228 {
 229         sdb_object_t *conn = c;
 230
 231         if (! conn)
 232                 return;
 233         sdb_object_deref(conn);
 234 } /* sdb_conn_ctx_destructor */
 235
 236 static void
 237 sdb_conn_ctx_init(void)
 238 {
 239         if (conn_ctx_key_initialized)
 240                 return;
 241
 242         pthread_key_create(&conn_ctx_key, sdb_conn_ctx_destructor);
 243         conn_ctx_key_initialized = 1;
 244 } /* sdb_conn_ctx_init */
 245
 246 static void
 247 sdb_conn_set_ctx(sdb_conn_t *conn)
 248 {
 249         sdb_conn_t *old;
 250
 251         sdb_conn_ctx_init();
 252
 253         old = pthread_getspecific(conn_ctx_key);
 254         if (old)
 255                 sdb_object_deref(SDB_OBJ(old));
 256         if (conn)
 257                 sdb_object_ref(SDB_OBJ(conn));
 258         pthread_setspecific(conn_ctx_key, conn);
 259 } /* sdb_conn_set_ctx */
 260
 261 static sdb_conn_t *
 262 sdb_conn_get_ctx(void)
 263 {
 264         if (! conn_ctx_key_initialized)
 265                 return NULL;
 266         return pthread_getspecific(conn_ctx_key);
 267 } /* sdb_conn_get_ctx */
 268
 269 /*
 270  * connection handler functions
 271  */
 272
 273 /*
 274  * connection_log:
 275  * Send a log message originating from the current thread to the client.
 276  */
 277 static int
 278 connection_log(int prio, const char *msg,
 279                 sdb_object_t __attribute__((unused)) *user_data)
 280 {
 281         uint32_t len = (uint32_t)sizeof(uint32_t) + (uint32_t)strlen(msg);
 282         uint32_t p = htonl((uint32_t)prio);
 283         char tmp[len + 1];
 284
 285         sdb_conn_t *conn;
 286
 287         conn = sdb_conn_get_ctx();
 288         /* no connection associated to this thread
 289          * or startup not done yet => don't leak any information */
 290         if ((! conn) || (! conn->ready))
 291                 return 0;
 292
 293         /* XXX: make the log-level configurable by the client at runtime */
 294         if (prio >= SDB_LOG_DEBUG)
 295                 return 0;
 296
 297         memcpy(tmp, &p, sizeof(p));
 298         strcpy(tmp + sizeof(p), msg);
 299
 300         if (sdb_connection_send(conn, SDB_CONNECTION_LOG, len, tmp) < 0)
 301                 return -1;
 302         return 0;
 303 } /* connection_log */
 304
 305 static int
 306 command_handle(sdb_conn_t *conn)
 307 {
 308         int status = -1;
 309
 310         assert(conn && (conn->cmd != SDB_CONNECTION_IDLE));
 311         assert(! conn->skip_len);
 312
 313         sdb_log(SDB_LOG_DEBUG, "frontend: Handling command %u (len: %u)",
 314                         conn->cmd, conn->cmd_len);
 315
 316         if (conn->cmd == SDB_CONNECTION_PING)
 317                 status = sdb_connection_ping(conn);
 318         else if (conn->cmd == SDB_CONNECTION_STARTUP)
 319                 status = sdb_fe_session_start(conn);
 320         else if (conn->cmd == SDB_CONNECTION_QUERY)
 321                 status = sdb_fe_query(conn);
 322         else if (conn->cmd == SDB_CONNECTION_FETCH)
 323                 status = sdb_fe_fetch(conn);
 324         else if (conn->cmd == SDB_CONNECTION_LIST)
 325                 status = sdb_fe_list(conn);
 326         else if (conn->cmd == SDB_CONNECTION_LOOKUP)
 327                 status = sdb_fe_lookup(conn);
 328         else {
 329                 sdb_log(SDB_LOG_WARNING, "frontend: Ignoring invalid command %#x",
 330                                 conn->cmd);
 331                 sdb_strbuf_sprintf(conn->errbuf, "Invalid command %#x", conn->cmd);
 332                 status = -1;
 333         }
 334
 335         if (status) {
 336                 if (! sdb_strbuf_len(conn->errbuf))
 337                         sdb_strbuf_sprintf(conn->errbuf, "Failed to execute command");
 338                 sdb_connection_send(conn, SDB_CONNECTION_ERROR,
 339                                 (uint32_t)sdb_strbuf_len(conn->errbuf),
 340                                 sdb_strbuf_string(conn->errbuf));
 341         }
 342         return status;
 343 } /* command_handle */
 344
 345 /* initialize the connection state information */
 346 static int
 347 command_init(sdb_conn_t *conn)
 348 {
 349         const char *errmsg = NULL;
 350
 351         assert(conn && (conn->cmd == SDB_CONNECTION_IDLE) && (! conn->cmd_len));
 352
 353         if (conn->skip_len)
 354                 return -1;
 355
 356         /* reset */
 357         sdb_strbuf_clear(conn->errbuf);
 358
 359         if (sdb_proto_unmarshal_header(SDB_STRBUF_STR(conn->buf),
 360                                 &conn->cmd, &conn->cmd_len))
 361                 return -1;
 362         sdb_strbuf_skip(conn->buf, 0, 2 * sizeof(uint32_t));
 363
 364         if ((! conn->ready) && (conn->cmd != SDB_CONNECTION_STARTUP))
 365                 errmsg = "Authentication required";
 366         else if (conn->cmd == SDB_CONNECTION_IDLE)
 367                 errmsg = "Invalid command 0";
 368
 369         if (errmsg) {
 370                 size_t len = sdb_strbuf_len(conn->buf);
 371
 372                 sdb_strbuf_sprintf(conn->errbuf, "%s", errmsg);
 373                 sdb_connection_send(conn, SDB_CONNECTION_ERROR,
 374                                 (uint32_t)strlen(errmsg), errmsg);
 375                 conn->skip_len += conn->cmd_len;
 376                 conn->cmd = SDB_CONNECTION_IDLE;
 377                 conn->cmd_len = 0;
 378
 379                 if (len > conn->skip_len)
 380                         len = conn->skip_len;
 381                 sdb_strbuf_skip(conn->buf, 0, len);
 382                 conn->skip_len -= len;
 383                 /* connection_read will handle anything else */
 384         }
 385         return 0;
 386 } /* command_init */
 387
 388 /* returns negative value on error, 0 on EOF, number of octets else */
 389 static ssize_t
 390 connection_read(sdb_conn_t *conn)
 391 {
 392         ssize_t n = 0;
 393
 394         if ((! conn) || (conn->fd < 0))
 395                 return -1;
 396
 397         while (42) {
 398                 ssize_t status;
 399
 400                 errno = 0;
 401                 status = sdb_strbuf_read(conn->buf, conn->fd, 1024);
 402                 if (status < 0) {
 403                         if ((errno == EAGAIN) || (errno == EWOULDBLOCK))
 404                                 break;
 405
 406                         sdb_connection_close(conn);
 407                         return (int)status;
 408                 }
 409                 else if (! status) /* EOF */
 410                         break;
 411
 412                 if (conn->skip_len) {
 413                         size_t len = (size_t)status < conn->skip_len
 414                                 ? (size_t)status : conn->skip_len;
 415                         sdb_strbuf_skip(conn->buf, 0, len);
 416                         conn->skip_len -= len;
 417                 }
 418
 419                 n += status;
 420
 421                 /* give the main loop a chance to execute commands (and free up buffer
 422                  * space) on large amounts of incoming traffic */
 423                 if (n > 1024 * 1024)
 424                         break;
 425         }
 426
 427         return n;
 428 } /* connection_read */
 429
 430 /*
 431  * public API
 432  */
 433
 434 int
 435 sdb_connection_enable_logging(void)
 436 {
 437         return sdb_plugin_register_log("connection-logger", connection_log,
 438                         /* user_data = */ NULL);
 439 } /* sdb_connection_enable_logging */
 440
 441 sdb_conn_t *
 442 sdb_connection_accept(int fd)
 443 {
 444         if (fd < 0)
 445                 return NULL;
 446
 447         /* the placeholder will be replaced with the accepted file
 448          * descriptor when initializing the object */
 449         return CONN(sdb_object_create(CONN_FD_PREFIX CONN_FD_PLACEHOLDER,
 450                                 connection_type, fd));
 451 } /* sdb_connection_create */
 452
 453 void
 454 sdb_connection_close(sdb_conn_t *conn)
 455 {
 456         if (! conn)
 457                 return;
 458
 459         /* close the connection even if someone else still references it */
 460         if (conn->fd >= 0)
 461                 close(conn->fd);
 462         conn->fd = -1;
 463 } /* sdb_connection_close */
 464
 465 ssize_t
 466 sdb_connection_handle(sdb_conn_t *conn)
 467 {
 468         ssize_t n = 0;
 469
 470         sdb_conn_set_ctx(conn);
 471
 472         while (42) {
 473                 ssize_t status = connection_read(conn);
 474
 475                 if ((conn->cmd == SDB_CONNECTION_IDLE) && (! conn->cmd_len)
 476                                 && (sdb_strbuf_len(conn->buf) >= 2 * sizeof(int32_t)))
 477                         command_init(conn);
 478                 if ((conn->cmd != SDB_CONNECTION_IDLE)
 479                                 && (sdb_strbuf_len(conn->buf) >= conn->cmd_len)) {
 480                         command_handle(conn);
 481
 482                         /* remove the command from the buffer */
 483                         if (conn->cmd_len)
 484                                 sdb_strbuf_skip(conn->buf, 0, conn->cmd_len);
 485                         conn->cmd = SDB_CONNECTION_IDLE;
 486                         conn->cmd_len = 0;
 487                 }
 488
 489                 if (status <= 0)
 490                         break;
 491
 492                 n += status;
 493         }
 494
 495         sdb_conn_set_ctx(NULL);
 496         return n;
 497 } /* sdb_connection_handle */
 498
 499 ssize_t
 500 sdb_connection_send(sdb_conn_t *conn, uint32_t code,
 501                 uint32_t msg_len, const char *msg)
 502 {
 503         char buf[2 * sizeof(uint32_t) + msg_len];
 504         ssize_t status;
 505
 506         if ((! conn) || (conn->fd < 0))
 507                 return -1;
 508         if (sdb_proto_marshal(buf, sizeof(buf), code, msg_len, msg) < 0)
 509                 return -1;
 510
 511         status = sdb_write(conn->fd, sizeof(buf), buf);
 512         if (status < 0) {
 513                 char errbuf[1024];
 514
 515                 /* tell other code that there was a problem and, more importantly,
 516                  * make sure we don't try to send further logs to the connection */
 517                 sdb_connection_close(conn);
 518                 conn->ready = 0;
 519
 520                 sdb_log(SDB_LOG_ERR, "frontend: Failed to send msg "
 521                                 "(code: %u, len: %u) to client: %s", code, msg_len,
 522                                 sdb_strerror(errno, errbuf, sizeof(errbuf)));
 523         }
 524         return status;
 525 } /* sdb_connection_send */
 526
 527 int
 528 sdb_connection_ping(sdb_conn_t *conn)
 529 {
 530         if ((! conn) || (conn->cmd != SDB_CONNECTION_PING))
 531                 return -1;
 532
 533         /* we're alive */
 534         sdb_connection_send(conn, SDB_CONNECTION_OK, 0, NULL);
 535         return 0;
 536 } /* sdb_connection_ping */
 537
 538 /* vim: set tw=78 sw=4 ts=4 noexpandtab : */
 539