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         if (conn->fd >= 0)
 205                 close(conn->fd);
 206         conn->fd = -1;
 207
 208         if (conn->username)
 209                 free(conn->username);
 210         conn->username = NULL;
 211
 212         sdb_strbuf_destroy(conn->buf);
 213         conn->buf = NULL;
 214         sdb_strbuf_destroy(conn->errbuf);
 215         conn->errbuf = NULL;
 216 } /* connection_destroy */
 217
 218 static sdb_type_t connection_type = {
 219         /* size = */ sizeof(sdb_conn_t),
 220         /* init = */ connection_init,
 221         /* destroy = */ connection_destroy,
 222 };
 223
 224 /*
 225  * private helper functions
 226  */
 227
 228 static void
 229 sdb_conn_ctx_destructor(void *c)
 230 {
 231         sdb_object_t *conn = c;
 232
 233         if (! conn)
 234                 return;
 235         sdb_object_deref(conn);
 236 } /* sdb_conn_ctx_destructor */
 237
 238 static void
 239 sdb_conn_ctx_init(void)
 240 {
 241         if (conn_ctx_key_initialized)
 242                 return;
 243
 244         pthread_key_create(&conn_ctx_key, sdb_conn_ctx_destructor);
 245         conn_ctx_key_initialized = 1;
 246 } /* sdb_conn_ctx_init */
 247
 248 static void
 249 sdb_conn_set_ctx(sdb_conn_t *conn)
 250 {
 251         sdb_conn_t *old;
 252
 253         sdb_conn_ctx_init();
 254
 255         old = pthread_getspecific(conn_ctx_key);
 256         if (old)
 257                 sdb_object_deref(SDB_OBJ(old));
 258         if (conn)
 259                 sdb_object_ref(SDB_OBJ(conn));
 260         pthread_setspecific(conn_ctx_key, conn);
 261 } /* sdb_conn_set_ctx */
 262
 263 static sdb_conn_t *
 264 sdb_conn_get_ctx(void)
 265 {
 266         if (! conn_ctx_key_initialized)
 267                 return NULL;
 268         return pthread_getspecific(conn_ctx_key);
 269 } /* sdb_conn_get_ctx */
 270
 271 /*
 272  * connection handler functions
 273  */
 274
 275 /*
 276  * connection_log:
 277  * Send a log message originating from the current thread to the client.
 278  */
 279 static int
 280 connection_log(int prio, const char *msg,
 281                 sdb_object_t __attribute__((unused)) *user_data)
 282 {
 283         uint32_t len = (uint32_t)sizeof(uint32_t) + (uint32_t)strlen(msg);
 284         uint32_t p = htonl((uint32_t)prio);
 285         char tmp[len + 1];
 286
 287         sdb_conn_t *conn;
 288
 289         conn = sdb_conn_get_ctx();
 290         /* no connection associated to this thread
 291          * or startup not done yet => don't leak any information */
 292         if ((! conn) || (! conn->ready))
 293                 return 0;
 294
 295         /* XXX: make the log-level configurable by the client at runtime */
 296         if (prio >= SDB_LOG_DEBUG)
 297                 return 0;
 298
 299         memcpy(tmp, &p, sizeof(p));
 300         strcpy(tmp + sizeof(p), msg);
 301
 302         if (sdb_connection_send(conn, SDB_CONNECTION_LOG, len, tmp) < 0)
 303                 return -1;
 304         return 0;
 305 } /* connection_log */
 306
 307 static int
 308 command_handle(sdb_conn_t *conn)
 309 {
 310         int status = -1;
 311
 312         assert(conn && (conn->cmd != SDB_CONNECTION_IDLE));
 313         assert(! conn->skip_len);
 314
 315         sdb_log(SDB_LOG_DEBUG, "frontend: Handling command %u (len: %u)",
 316                         conn->cmd, conn->cmd_len);
 317
 318         if (conn->cmd == SDB_CONNECTION_PING)
 319                 status = sdb_connection_ping(conn);
 320         else if (conn->cmd == SDB_CONNECTION_STARTUP)
 321                 status = sdb_fe_session_start(conn);
 322         else if (conn->cmd == SDB_CONNECTION_QUERY)
 323                 status = sdb_fe_query(conn);
 324         else if (conn->cmd == SDB_CONNECTION_FETCH)
 325                 status = sdb_fe_fetch(conn);
 326         else if (conn->cmd == SDB_CONNECTION_LIST)
 327                 status = sdb_fe_list(conn);
 328         else if (conn->cmd == SDB_CONNECTION_LOOKUP)
 329                 status = sdb_fe_lookup(conn);
 330         else {
 331                 sdb_log(SDB_LOG_WARNING, "frontend: Ignoring invalid command %#x",
 332                                 conn->cmd);
 333                 sdb_strbuf_sprintf(conn->errbuf, "Invalid command %#x", conn->cmd);
 334                 status = -1;
 335         }
 336
 337         if (status) {
 338                 if (! sdb_strbuf_len(conn->errbuf))
 339                         sdb_strbuf_sprintf(conn->errbuf, "Failed to execute command");
 340                 sdb_connection_send(conn, SDB_CONNECTION_ERROR,
 341                                 (uint32_t)sdb_strbuf_len(conn->errbuf),
 342                                 sdb_strbuf_string(conn->errbuf));
 343         }
 344         return status;
 345 } /* command_handle */
 346
 347 /* initialize the connection state information */
 348 static int
 349 command_init(sdb_conn_t *conn)
 350 {
 351         const char *errmsg = NULL;
 352
 353         assert(conn && (conn->cmd == SDB_CONNECTION_IDLE) && (! conn->cmd_len));
 354
 355         if (conn->skip_len)
 356                 return -1;
 357
 358         /* reset */
 359         sdb_strbuf_clear(conn->errbuf);
 360
 361         if (sdb_proto_unmarshal_header(conn->buf, &conn->cmd, &conn->cmd_len))
 362                 return -1;
 363         sdb_strbuf_skip(conn->buf, 0, 2 * sizeof(uint32_t));
 364
 365         if ((! conn->ready) && (conn->cmd != SDB_CONNECTION_STARTUP))
 366                 errmsg = "Authentication required";
 367         else if (conn->cmd == SDB_CONNECTION_IDLE)
 368                 errmsg = "Invalid command 0";
 369
 370         if (errmsg) {
 371                 size_t len = sdb_strbuf_len(conn->buf);
 372
 373                 sdb_strbuf_sprintf(conn->errbuf, "%s", errmsg);
 374                 sdb_connection_send(conn, SDB_CONNECTION_ERROR,
 375                                 (uint32_t)strlen(errmsg), errmsg);
 376                 conn->skip_len += conn->cmd_len;
 377                 conn->cmd = SDB_CONNECTION_IDLE;
 378                 conn->cmd_len = 0;
 379
 380                 if (len > conn->skip_len)
 381                         len = conn->skip_len;
 382                 sdb_strbuf_skip(conn->buf, 0, len);
 383                 conn->skip_len -= len;
 384                 /* connection_read will handle anything else */
 385         }
 386         return 0;
 387 } /* command_init */
 388
 389 /* returns negative value on error, 0 on EOF, number of octets else */
 390 static ssize_t
 391 connection_read(sdb_conn_t *conn)
 392 {
 393         ssize_t n = 0;
 394
 395         if ((! conn) || (conn->fd < 0))
 396                 return -1;
 397
 398         while (42) {
 399                 ssize_t status;
 400
 401                 errno = 0;
 402                 status = sdb_strbuf_read(conn->buf, conn->fd, 1024);
 403                 if (status < 0) {
 404                         if ((errno == EAGAIN) || (errno == EWOULDBLOCK))
 405                                 break;
 406
 407                         close(conn->fd);
 408                         conn->fd = -1;
 409                         return (int)status;
 410                 }
 411                 else if (! status) /* EOF */
 412                         break;
 413
 414                 if (conn->skip_len) {
 415                         size_t len = (size_t)status < conn->skip_len
 416                                 ? (size_t)status : conn->skip_len;
 417                         sdb_strbuf_skip(conn->buf, 0, len);
 418                         conn->skip_len -= len;
 419                 }
 420
 421                 n += status;
 422
 423                 /* give the main loop a chance to execute commands (and free up buffer
 424                  * space) on large amounts of incoming traffic */
 425                 if (n > 1024 * 1024)
 426                         break;
 427         }
 428
 429         return n;
 430 } /* connection_read */
 431
 432 /*
 433  * public API
 434  */
 435
 436 int
 437 sdb_connection_enable_logging(void)
 438 {
 439         return sdb_plugin_register_log("connection-logger", connection_log,
 440                         /* user_data = */ NULL);
 441 } /* sdb_connection_enable_logging */
 442
 443 sdb_conn_t *
 444 sdb_connection_accept(int fd)
 445 {
 446         if (fd < 0)
 447                 return NULL;
 448
 449         /* the placeholder will be replaced with the accepted file
 450          * descriptor when initializing the object */
 451         return CONN(sdb_object_create(CONN_FD_PREFIX CONN_FD_PLACEHOLDER,
 452                                 connection_type, fd));
 453 } /* sdb_connection_create */
 454
 455 void
 456 sdb_connection_close(sdb_conn_t *conn)
 457 {
 458         if (! conn)
 459                 return;
 460
 461         /* close the connection even if someone else still references it */
 462         if (conn->fd >= 0)
 463                 close(conn->fd);
 464         conn->fd = -1;
 465 } /* sdb_connection_close */
 466
 467 ssize_t
 468 sdb_connection_handle(sdb_conn_t *conn)
 469 {
 470         ssize_t n = 0;
 471
 472         sdb_conn_set_ctx(conn);
 473
 474         while (42) {
 475                 ssize_t status = connection_read(conn);
 476
 477                 if ((conn->cmd == SDB_CONNECTION_IDLE) && (! conn->cmd_len)
 478                                 && (sdb_strbuf_len(conn->buf) >= 2 * sizeof(int32_t)))
 479                         command_init(conn);
 480                 if ((conn->cmd != SDB_CONNECTION_IDLE)
 481                                 && (sdb_strbuf_len(conn->buf) >= conn->cmd_len)) {
 482                         command_handle(conn);
 483
 484                         /* remove the command from the buffer */
 485                         if (conn->cmd_len)
 486                                 sdb_strbuf_skip(conn->buf, 0, conn->cmd_len);
 487                         conn->cmd = SDB_CONNECTION_IDLE;
 488                         conn->cmd_len = 0;
 489                 }
 490
 491                 if (status <= 0)
 492                         break;
 493
 494                 n += status;
 495         }
 496
 497         sdb_conn_set_ctx(NULL);
 498         return n;
 499 } /* sdb_connection_handle */
 500
 501 ssize_t
 502 sdb_connection_send(sdb_conn_t *conn, uint32_t code,
 503                 uint32_t msg_len, const char *msg)
 504 {
 505         char buf[2 * sizeof(uint32_t) + msg_len];
 506         ssize_t status;
 507
 508         if ((! conn) || (conn->fd < 0))
 509                 return -1;
 510         if (sdb_proto_marshal(buf, sizeof(buf), code, msg_len, msg) < 0)
 511                 return -1;
 512
 513         status = sdb_write(conn->fd, sizeof(buf), buf);
 514         if (status < 0) {
 515                 char errbuf[1024];
 516
 517                 /* tell other code that there was a problem and, more importantly,
 518                  * make sure we don't try to send further logs to the connection */
 519                 close(conn->fd);
 520                 conn->fd = -1;
 521                 conn->ready = 0;
 522
 523                 sdb_log(SDB_LOG_ERR, "frontend: Failed to send msg "
 524                                 "(code: %u, len: %u) to client: %s", code, msg_len,
 525                                 sdb_strerror(errno, errbuf, sizeof(errbuf)));
 526         }
 527         return status;
 528 } /* sdb_connection_send */
 529
 530 int
 531 sdb_connection_ping(sdb_conn_t *conn)
 532 {
 533         if ((! conn) || (conn->cmd != SDB_CONNECTION_PING))
 534                 return -1;
 535
 536         /* we're alive */
 537         sdb_connection_send(conn, SDB_CONNECTION_OK, 0, NULL);
 538         return 0;
 539 } /* sdb_connection_ping */
 540
 541 /* vim: set tw=78 sw=4 ts=4 noexpandtab : */
 542