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 ssize_t
 111 conn_read(sdb_conn_t *conn, size_t len)
 112 {
 113         return sdb_strbuf_read(conn->buf, conn->fd, len);
 114 } /* conn_read */
 115
 116 static ssize_t
 117 conn_write(sdb_conn_t *conn, const void *buf, size_t len)
 118 {
 119         return sdb_write(conn->fd, len, buf);
 120 } /* conn_write */
 121
 122 static int
 123 connection_init(sdb_object_t *obj, va_list ap)
 124 {
 125         sdb_conn_t *conn;
 126         int sock_fd;
 127         int sock_fl;
 128
 129         assert(obj);
 130         conn = CONN(obj);
 131
 132         sock_fd = va_arg(ap, int);
 133
 134         conn->buf = sdb_strbuf_create(/* size = */ 128);
 135         if (! conn->buf) {
 136                 sdb_log(SDB_LOG_ERR, "frontend: Failed to allocate a read buffer "
 137                                 "for a new connection");
 138                 return -1;
 139         }
 140         conn->errbuf = sdb_strbuf_create(0);
 141         if (! conn->errbuf) {
 142                 sdb_log(SDB_LOG_ERR, "frontend: Failed to allocate an error buffer "
 143                                 "for a new connection");
 144                 return -1;
 145         }
 146
 147         conn->client_addr_len = sizeof(conn->client_addr);
 148         conn->fd = accept(sock_fd, (struct sockaddr *)&conn->client_addr,
 149                         &conn->client_addr_len);
 150
 151         if (conn->fd < 0) {
 152                 char buf[1024];
 153                 sdb_log(SDB_LOG_ERR, "frontend: Failed to accept remote "
 154                                 "connection: %s", sdb_strerror(errno,
 155                                         buf, sizeof(buf)));
 156                 return -1;
 157         }
 158
 159         /* defaults */
 160         conn->read = conn_read;
 161         conn->write = conn_write;
 162         conn->finish = NULL;
 163         conn->session = NULL;
 164
 165         if (conn->client_addr.ss_family != AF_UNIX) {
 166                 sdb_log(SDB_LOG_ERR, "frontend: Accepted connection using "
 167                                 "unexpected family type %d", conn->client_addr.ss_family);
 168                 return -1;
 169         }
 170
 171         sock_fl = fcntl(conn->fd, F_GETFL);
 172         if (fcntl(conn->fd, F_SETFL, sock_fl | O_NONBLOCK)) {
 173                 char buf[1024];
 174                 sdb_log(SDB_LOG_ERR, "frontend: Failed to switch connection conn#%i "
 175                                 "to non-blocking mode: %s", conn->fd,
 176                                 sdb_strerror(errno, buf, sizeof(buf)));
 177                 return -1;
 178         }
 179
 180         conn->username = peer(conn->fd);
 181         if (! conn->username) {
 182                 char buf[1024];
 183                 sdb_log(SDB_LOG_ERR, "frontend: Failed to retrieve peer for "
 184                                 "connection conn#%i: %s", conn->fd,
 185                                 sdb_strerror(errno, buf, sizeof(buf)));
 186                 return -1;
 187         }
 188         conn->ready = 0;
 189
 190         sdb_log(SDB_LOG_DEBUG, "frontend: Accepted connection on fd=%i",
 191                         conn->fd);
 192
 193         conn->cmd = SDB_CONNECTION_IDLE;
 194         conn->cmd_len = 0;
 195         conn->skip_len = 0;
 196
 197         /* update the object name */
 198         snprintf(obj->name + strlen(CONN_FD_PREFIX),
 199                         strlen(CONN_FD_PLACEHOLDER), "%i", conn->fd);
 200         return 0;
 201 } /* connection_init */
 202
 203 static void
 204 connection_destroy(sdb_object_t *obj)
 205 {
 206         sdb_conn_t *conn;
 207         size_t len;
 208
 209         assert(obj);
 210         conn = CONN(obj);
 211
 212         conn->ready = 0;
 213
 214         if (conn->finish)
 215                 conn->finish(conn);
 216         conn->finish = NULL;
 217
 218         if (conn->buf) {
 219                 len = sdb_strbuf_len(conn->buf);
 220                 if (len)
 221                         sdb_log(SDB_LOG_INFO, "frontend: Discarding incomplete command "
 222                                         "(%zu byte%s left in buffer)", len, len == 1 ? "" : "s");
 223         }
 224
 225         sdb_log(SDB_LOG_DEBUG, "frontend: Closing connection %s", obj->name);
 226         sdb_connection_close(conn);
 227
 228         if (conn->username)
 229                 free(conn->username);
 230         conn->username = NULL;
 231
 232         sdb_strbuf_destroy(conn->buf);
 233         conn->buf = NULL;
 234         sdb_strbuf_destroy(conn->errbuf);
 235         conn->errbuf = NULL;
 236 } /* connection_destroy */
 237
 238 static sdb_type_t connection_type = {
 239         /* size = */ sizeof(sdb_conn_t),
 240         /* init = */ connection_init,
 241         /* destroy = */ connection_destroy,
 242 };
 243
 244 /*
 245  * private helper functions
 246  */
 247
 248 static void
 249 sdb_conn_ctx_destructor(void *c)
 250 {
 251         sdb_object_t *conn = c;
 252
 253         if (! conn)
 254                 return;
 255         sdb_object_deref(conn);
 256 } /* sdb_conn_ctx_destructor */
 257
 258 static void
 259 sdb_conn_ctx_init(void)
 260 {
 261         if (conn_ctx_key_initialized)
 262                 return;
 263
 264         pthread_key_create(&conn_ctx_key, sdb_conn_ctx_destructor);
 265         conn_ctx_key_initialized = 1;
 266 } /* sdb_conn_ctx_init */
 267
 268 static void
 269 sdb_conn_set_ctx(sdb_conn_t *conn)
 270 {
 271         sdb_conn_t *old;
 272
 273         sdb_conn_ctx_init();
 274
 275         old = pthread_getspecific(conn_ctx_key);
 276         if (old)
 277                 sdb_object_deref(SDB_OBJ(old));
 278         if (conn)
 279                 sdb_object_ref(SDB_OBJ(conn));
 280         pthread_setspecific(conn_ctx_key, conn);
 281 } /* sdb_conn_set_ctx */
 282
 283 static sdb_conn_t *
 284 sdb_conn_get_ctx(void)
 285 {
 286         if (! conn_ctx_key_initialized)
 287                 return NULL;
 288         return pthread_getspecific(conn_ctx_key);
 289 } /* sdb_conn_get_ctx */
 290
 291 /*
 292  * connection handler functions
 293  */
 294
 295 /*
 296  * connection_log:
 297  * Send a log message originating from the current thread to the client.
 298  */
 299 static int
 300 connection_log(int prio, const char *msg,
 301                 sdb_object_t __attribute__((unused)) *user_data)
 302 {
 303         uint32_t len = (uint32_t)sizeof(uint32_t) + (uint32_t)strlen(msg);
 304         uint32_t p = htonl((uint32_t)prio);
 305         char tmp[len + 1];
 306
 307         sdb_conn_t *conn;
 308
 309         conn = sdb_conn_get_ctx();
 310         /* no connection associated to this thread
 311          * or startup not done yet => don't leak any information */
 312         if ((! conn) || (! conn->ready))
 313                 return 0;
 314
 315         /* XXX: make the log-level configurable by the client at runtime */
 316         if (prio >= SDB_LOG_DEBUG)
 317                 return 0;
 318
 319         memcpy(tmp, &p, sizeof(p));
 320         strcpy(tmp + sizeof(p), msg);
 321
 322         if (sdb_connection_send(conn, SDB_CONNECTION_LOG, len, tmp) < 0)
 323                 return -1;
 324         return 0;
 325 } /* connection_log */
 326
 327 static int
 328 command_handle(sdb_conn_t *conn)
 329 {
 330         int status = -1;
 331
 332         assert(conn && (conn->cmd != SDB_CONNECTION_IDLE));
 333         assert(! conn->skip_len);
 334
 335         sdb_log(SDB_LOG_DEBUG, "frontend: Handling command %u (len: %u)",
 336                         conn->cmd, conn->cmd_len);
 337
 338         if (conn->cmd == SDB_CONNECTION_PING)
 339                 status = sdb_connection_ping(conn);
 340         else if (conn->cmd == SDB_CONNECTION_STARTUP)
 341                 status = sdb_fe_session_start(conn);
 342         else if (conn->cmd == SDB_CONNECTION_QUERY)
 343                 status = sdb_fe_query(conn);
 344         else if (conn->cmd == SDB_CONNECTION_FETCH)
 345                 status = sdb_fe_fetch(conn);
 346         else if (conn->cmd == SDB_CONNECTION_LIST)
 347                 status = sdb_fe_list(conn);
 348         else if (conn->cmd == SDB_CONNECTION_LOOKUP)
 349                 status = sdb_fe_lookup(conn);
 350         else if (conn->cmd == SDB_CONNECTION_STORE)
 351                 status = sdb_fe_store(conn);
 352         else {
 353                 sdb_log(SDB_LOG_WARNING, "frontend: Ignoring invalid command %#x",
 354                                 conn->cmd);
 355                 sdb_strbuf_sprintf(conn->errbuf, "Invalid command %#x", conn->cmd);
 356                 status = -1;
 357         }
 358
 359         if (status) {
 360                 if (! sdb_strbuf_len(conn->errbuf))
 361                         sdb_strbuf_sprintf(conn->errbuf, "Failed to execute command");
 362                 sdb_connection_send(conn, SDB_CONNECTION_ERROR,
 363                                 (uint32_t)sdb_strbuf_len(conn->errbuf),
 364                                 sdb_strbuf_string(conn->errbuf));
 365         }
 366         return status;
 367 } /* command_handle */
 368
 369 /* initialize the connection state information */
 370 static int
 371 command_init(sdb_conn_t *conn)
 372 {
 373         const char *errmsg = NULL;
 374
 375         assert(conn && (conn->cmd == SDB_CONNECTION_IDLE) && (! conn->cmd_len));
 376
 377         if (conn->skip_len)
 378                 return -1;
 379
 380         /* reset */
 381         sdb_strbuf_clear(conn->errbuf);
 382
 383         if (sdb_proto_unmarshal_header(SDB_STRBUF_STR(conn->buf),
 384                                 &conn->cmd, &conn->cmd_len) < 0)
 385                 return -1;
 386         sdb_strbuf_skip(conn->buf, 0, 2 * sizeof(uint32_t));
 387
 388         if ((! conn->ready) && (conn->cmd != SDB_CONNECTION_STARTUP))
 389                 errmsg = "Authentication required";
 390         else if (conn->cmd == SDB_CONNECTION_IDLE)
 391                 errmsg = "Invalid command 0";
 392
 393         if (errmsg) {
 394                 size_t len = sdb_strbuf_len(conn->buf);
 395
 396                 sdb_strbuf_sprintf(conn->errbuf, "%s", errmsg);
 397                 sdb_connection_send(conn, SDB_CONNECTION_ERROR,
 398                                 (uint32_t)strlen(errmsg), errmsg);
 399                 conn->skip_len += conn->cmd_len;
 400                 conn->cmd = SDB_CONNECTION_IDLE;
 401                 conn->cmd_len = 0;
 402
 403                 if (len > conn->skip_len)
 404                         len = conn->skip_len;
 405                 sdb_strbuf_skip(conn->buf, 0, len);
 406                 conn->skip_len -= len;
 407                 /* connection_read will handle anything else */
 408         }
 409         return 0;
 410 } /* command_init */
 411
 412 /* returns negative value on error, 0 on EOF, number of octets else */
 413 static ssize_t
 414 connection_read(sdb_conn_t *conn)
 415 {
 416         ssize_t n = 0;
 417
 418         if ((! conn) || (conn->fd < 0))
 419                 return -1;
 420
 421         while (42) {
 422                 ssize_t status;
 423
 424                 errno = 0;
 425                 status = conn->read(conn, 1024);
 426                 if (status < 0) {
 427                         if ((errno == EAGAIN) || (errno == EWOULDBLOCK))
 428                                 break;
 429
 430                         sdb_connection_close(conn);
 431                         return (int)status;
 432                 }
 433                 else if (! status) /* EOF */
 434                         break;
 435
 436                 if (conn->skip_len) {
 437                         size_t len = (size_t)status < conn->skip_len
 438                                 ? (size_t)status : conn->skip_len;
 439                         sdb_strbuf_skip(conn->buf, 0, len);
 440                         conn->skip_len -= len;
 441                 }
 442
 443                 n += status;
 444
 445                 /* give the main loop a chance to execute commands (and free up buffer
 446                  * space) on large amounts of incoming traffic */
 447                 if (n > 1024 * 1024)
 448                         break;
 449         }
 450
 451         return n;
 452 } /* connection_read */
 453
 454 /*
 455  * public API
 456  */
 457
 458 int
 459 sdb_connection_enable_logging(void)
 460 {
 461         return sdb_plugin_register_log("connection-logger", connection_log,
 462                         /* user_data = */ NULL);
 463 } /* sdb_connection_enable_logging */
 464
 465 sdb_conn_t *
 466 sdb_connection_accept(int fd)
 467 {
 468         if (fd < 0)
 469                 return NULL;
 470
 471         /* the placeholder will be replaced with the accepted file
 472          * descriptor when initializing the object */
 473         return CONN(sdb_object_create(CONN_FD_PREFIX CONN_FD_PLACEHOLDER,
 474                                 connection_type, fd));
 475 } /* sdb_connection_create */
 476
 477 void
 478 sdb_connection_close(sdb_conn_t *conn)
 479 {
 480         if (! conn)
 481                 return;
 482
 483         if (conn->finish)
 484                 conn->finish(conn);
 485         conn->finish = NULL;
 486
 487         /* close the connection even if someone else still references it */
 488         if (conn->fd >= 0)
 489                 close(conn->fd);
 490         conn->fd = -1;
 491 } /* sdb_connection_close */
 492
 493 ssize_t
 494 sdb_connection_handle(sdb_conn_t *conn)
 495 {
 496         ssize_t n = 0;
 497
 498         sdb_conn_set_ctx(conn);
 499
 500         while (42) {
 501                 ssize_t status = connection_read(conn);
 502
 503                 if ((conn->cmd == SDB_CONNECTION_IDLE) && (! conn->cmd_len)
 504                                 && (sdb_strbuf_len(conn->buf) >= 2 * sizeof(int32_t)))
 505                         command_init(conn);
 506                 if ((conn->cmd != SDB_CONNECTION_IDLE)
 507                                 && (sdb_strbuf_len(conn->buf) >= conn->cmd_len)) {
 508                         command_handle(conn);
 509
 510                         /* remove the command from the buffer */
 511                         if (conn->cmd_len)
 512                                 sdb_strbuf_skip(conn->buf, 0, conn->cmd_len);
 513                         conn->cmd = SDB_CONNECTION_IDLE;
 514                         conn->cmd_len = 0;
 515                 }
 516
 517                 if (status <= 0)
 518                         break;
 519
 520                 n += status;
 521         }
 522
 523         sdb_conn_set_ctx(NULL);
 524         return n;
 525 } /* sdb_connection_handle */
 526
 527 ssize_t
 528 sdb_connection_send(sdb_conn_t *conn, uint32_t code,
 529                 uint32_t msg_len, const char *msg)
 530 {
 531         char buf[2 * sizeof(uint32_t) + msg_len];
 532         ssize_t status;
 533
 534         if ((! conn) || (conn->fd < 0))
 535                 return -1;
 536         if (sdb_proto_marshal(buf, sizeof(buf), code, msg_len, msg) < 0)
 537                 return -1;
 538
 539         status = conn->write(conn, buf, sizeof(buf));
 540         if (status < 0) {
 541                 char errbuf[1024];
 542
 543                 /* tell other code that there was a problem and, more importantly,
 544                  * make sure we don't try to send further logs to the connection */
 545                 sdb_connection_close(conn);
 546                 conn->ready = 0;
 547
 548                 sdb_log(SDB_LOG_ERR, "frontend: Failed to send msg "
 549                                 "(code: %u, len: %u) to client: %s", code, msg_len,
 550                                 sdb_strerror(errno, errbuf, sizeof(errbuf)));
 551         }
 552         return status;
 553 } /* sdb_connection_send */
 554
 555 int
 556 sdb_connection_ping(sdb_conn_t *conn)
 557 {
 558         if ((! conn) || (conn->cmd != SDB_CONNECTION_PING))
 559                 return -1;
 560
 561         /* we're alive */
 562         sdb_connection_send(conn, SDB_CONNECTION_OK, 0, NULL);
 563         return 0;
 564 } /* sdb_connection_ping */
 565
 566 /* vim: set tw=78 sw=4 ts=4 noexpandtab : */
 567