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
  40 #include <assert.h>
  41 #include <errno.h>
  42
  43 #include <arpa/inet.h>
  44 #include <fcntl.h>
  45
  46 #include <stdlib.h>
  47 #include <string.h>
  48
  49 #include <sys/socket.h>
  50 #include <sys/types.h>
  51 #include <sys/param.h>
  52
  53 #ifdef HAVE_UCRED_H
  54 #       include <ucred.h>
  55 #endif
  56 #ifdef HAVE_SYS_UCRED_H
  57 #       include <sys/ucred.h>
  58 #endif
  59
  60 #include <pwd.h>
  61
  62 #include <pthread.h>
  63
  64 /*
  65  * private variables
  66  */
  67
  68 static pthread_key_t conn_ctx_key;
  69 static bool          conn_ctx_key_initialized = 0;
  70
  71 /*
  72  * private types
  73  */
  74
  75 /* name of connection objects */
  76 #define CONN_FD_PREFIX "conn#"
  77 #define CONN_FD_PLACEHOLDER "XXXXXXX"
  78
  79 /* XXX: only supports UNIX sockets so far */
  80 static char *
  81 peer(int sockfd)
  82 {
  83         uid_t uid;
  84
  85         struct passwd pw_entry;
  86         struct passwd *result = NULL;
  87         char buf[1024];
  88
  89 #ifdef SO_PEERCRED
  90         struct ucred cred;
  91         socklen_t len = sizeof(cred);
  92
  93         if (getsockopt(sockfd, SOL_SOCKET, SO_PEERCRED, &cred, &len)
  94                         || (len != sizeof(cred)))
  95                 return NULL;
  96         uid = cred.uid;
  97 #else /* SO_PEERCRED */
  98         errno = ENOSYS;
  99         return NULL;
 100 #endif
 101
 102         memset(&pw_entry, 0, sizeof(pw_entry));
 103         if (getpwuid_r(uid, &pw_entry, buf, sizeof(buf), &result)
 104                         || (! result))
 105                 return NULL;
 106         return strdup(result->pw_name);
 107 } /* peer */
 108
 109 static int
 110 connection_init(sdb_object_t *obj, va_list ap)
 111 {
 112         sdb_conn_t *conn;
 113         int sock_fd;
 114         int sock_fl;
 115
 116         assert(obj);
 117         conn = CONN(obj);
 118
 119         sock_fd = va_arg(ap, int);
 120
 121         conn->buf = sdb_strbuf_create(/* size = */ 128);
 122         if (! conn->buf) {
 123                 sdb_log(SDB_LOG_ERR, "frontend: Failed to allocate a read buffer "
 124                                 "for a new connection");
 125                 return -1;
 126         }
 127         conn->errbuf = sdb_strbuf_create(0);
 128         if (! conn->errbuf) {
 129                 sdb_log(SDB_LOG_ERR, "frontend: Failed to allocate an error buffer "
 130                                 "for a new connection");
 131                 return -1;
 132         }
 133
 134         conn->client_addr_len = sizeof(conn->client_addr);
 135         conn->fd = accept(sock_fd, (struct sockaddr *)&conn->client_addr,
 136                         &conn->client_addr_len);
 137
 138         if (conn->fd < 0) {
 139                 char buf[1024];
 140                 sdb_log(SDB_LOG_ERR, "frontend: Failed to accept remote "
 141                                 "connection: %s", sdb_strerror(errno,
 142                                         buf, sizeof(buf)));
 143                 return -1;
 144         }
 145
 146         if (conn->client_addr.ss_family != AF_UNIX) {
 147                 sdb_log(SDB_LOG_ERR, "frontend: Accepted connection using "
 148                                 "unexpected family type %d", conn->client_addr.ss_family);
 149                 return -1;
 150         }
 151
 152         sock_fl = fcntl(conn->fd, F_GETFL);
 153         if (fcntl(conn->fd, F_SETFL, sock_fl | O_NONBLOCK)) {
 154                 char buf[1024];
 155                 sdb_log(SDB_LOG_ERR, "frontend: Failed to switch connection conn#%i "
 156                                 "to non-blocking mode: %s", conn->fd,
 157                                 sdb_strerror(errno, buf, sizeof(buf)));
 158                 return -1;
 159         }
 160
 161         conn->username = peer(conn->fd);
 162         if (! conn->username) {
 163                 char buf[1024];
 164                 sdb_log(SDB_LOG_ERR, "frontend: Failed to retrieve peer for "
 165                                 "connection conn#%i: %s", conn->fd,
 166                                 sdb_strerror(errno, buf, sizeof(buf)));
 167                 return -1;
 168         }
 169         conn->ready = 0;
 170
 171         sdb_log(SDB_LOG_DEBUG, "frontend: Accepted connection on fd=%i",
 172                         conn->fd);
 173
 174         conn->cmd = SDB_CONNECTION_IDLE;
 175         conn->cmd_len = 0;
 176         conn->skip_len = 0;
 177
 178         /* update the object name */
 179         snprintf(obj->name + strlen(CONN_FD_PREFIX),
 180                         strlen(CONN_FD_PLACEHOLDER), "%i", conn->fd);
 181         return 0;
 182 } /* connection_init */
 183
 184 static void
 185 connection_destroy(sdb_object_t *obj)
 186 {
 187         sdb_conn_t *conn;
 188         size_t len;
 189
 190         assert(obj);
 191         conn = CONN(obj);
 192
 193         conn->ready = 0;
 194
 195         if (conn->buf) {
 196                 len = sdb_strbuf_len(conn->buf);
 197                 if (len)
 198                         sdb_log(SDB_LOG_INFO, "frontend: Discarding incomplete command "
 199                                         "(%zu byte%s left in buffer)", len, len == 1 ? "" : "s");
 200         }
 201
 202         sdb_log(SDB_LOG_DEBUG, "frontend: Closing connection %s", obj->name);
 203         if (conn->fd >= 0)
 204                 close(conn->fd);
 205         conn->fd = -1;
 206
 207         if (conn->username)
 208                 free(conn->username);
 209         conn->username = NULL;
 210
 211         sdb_strbuf_destroy(conn->buf);
 212         conn->buf = NULL;
 213         sdb_strbuf_destroy(conn->errbuf);
 214         conn->errbuf = NULL;
 215 } /* connection_destroy */
 216
 217 static sdb_type_t connection_type = {
 218         /* size = */ sizeof(sdb_conn_t),
 219         /* init = */ connection_init,
 220         /* destroy = */ connection_destroy,
 221 };
 222
 223 /*
 224  * private helper functions
 225  */
 226
 227 static void
 228 sdb_conn_ctx_destructor(void *c)
 229 {
 230         sdb_object_t *conn = c;
 231
 232         if (! conn)
 233                 return;
 234         sdb_object_deref(conn);
 235 } /* sdb_conn_ctx_destructor */
 236
 237 static void
 238 sdb_conn_ctx_init(void)
 239 {
 240         if (conn_ctx_key_initialized)
 241                 return;
 242
 243         pthread_key_create(&conn_ctx_key, sdb_conn_ctx_destructor);
 244         conn_ctx_key_initialized = 1;
 245 } /* sdb_conn_ctx_init */
 246
 247 static void
 248 sdb_conn_set_ctx(sdb_conn_t *conn)
 249 {
 250         sdb_conn_t *old;
 251
 252         sdb_conn_ctx_init();
 253
 254         old = pthread_getspecific(conn_ctx_key);
 255         if (old)
 256                 sdb_object_deref(SDB_OBJ(old));
 257         if (conn)
 258                 sdb_object_ref(SDB_OBJ(conn));
 259         pthread_setspecific(conn_ctx_key, conn);
 260 } /* sdb_conn_set_ctx */
 261
 262 static sdb_conn_t *
 263 sdb_conn_get_ctx(void)
 264 {
 265         if (! conn_ctx_key_initialized)
 266                 return NULL;
 267         return pthread_getspecific(conn_ctx_key);
 268 } /* sdb_conn_get_ctx */
 269
 270 /*
 271  * connection handler functions
 272  */
 273
 274 /*
 275  * connection_log:
 276  * Send a log message originating from the current thread to the client.
 277  */
 278 static int
 279 connection_log(int prio, const char *msg,
 280                 sdb_object_t __attribute__((unused)) *user_data)
 281 {
 282         uint32_t len = (uint32_t)sizeof(uint32_t) + (uint32_t)strlen(msg);
 283         uint32_t p = htonl((uint32_t)prio);
 284         char tmp[len + 1];
 285
 286         sdb_conn_t *conn;
 287
 288         conn = sdb_conn_get_ctx();
 289         /* no connection associated to this thread
 290          * or startup not done yet => don't leak any information */
 291         if ((! conn) || (! conn->ready))
 292                 return 0;
 293
 294         /* XXX: make the log-level configurable by the client at runtime */
 295         if (prio >= SDB_LOG_DEBUG)
 296                 return 0;
 297
 298         memcpy(tmp, &p, sizeof(p));
 299         strcpy(tmp + sizeof(p), msg);
 300
 301         if (sdb_connection_send(conn, SDB_CONNECTION_LOG, len, tmp) < 0)
 302                 return -1;
 303         return 0;
 304 } /* connection_log */
 305
 306 static int
 307 command_handle(sdb_conn_t *conn)
 308 {
 309         int status = -1;
 310
 311         assert(conn && (conn->cmd != SDB_CONNECTION_IDLE));
 312         assert(! conn->skip_len);
 313
 314         sdb_log(SDB_LOG_DEBUG, "frontend: Handling command %u (len: %u)",
 315                         conn->cmd, conn->cmd_len);
 316
 317         if (conn->cmd == SDB_CONNECTION_PING)
 318                 status = sdb_connection_ping(conn);
 319         else if (conn->cmd == SDB_CONNECTION_STARTUP)
 320                 status = sdb_fe_session_start(conn);
 321         else if (conn->cmd == SDB_CONNECTION_QUERY)
 322                 status = sdb_fe_query(conn);
 323         else if (conn->cmd == SDB_CONNECTION_FETCH)
 324                 status = sdb_fe_fetch(conn);
 325         else if (conn->cmd == SDB_CONNECTION_LIST)
 326                 status = sdb_fe_list(conn);
 327         else if (conn->cmd == SDB_CONNECTION_LOOKUP)
 328                 status = sdb_fe_lookup(conn);
 329         else {
 330                 sdb_log(SDB_LOG_WARNING, "frontend: Ignoring invalid command %#x",
 331                                 conn->cmd);
 332                 sdb_strbuf_sprintf(conn->errbuf, "Invalid command %#x", conn->cmd);
 333                 status = -1;
 334         }
 335
 336         if (status) {
 337                 if (! sdb_strbuf_len(conn->errbuf))
 338                         sdb_strbuf_sprintf(conn->errbuf, "Failed to execute command");
 339                 sdb_connection_send(conn, SDB_CONNECTION_ERROR,
 340                                 (uint32_t)sdb_strbuf_len(conn->errbuf),
 341                                 sdb_strbuf_string(conn->errbuf));
 342         }
 343         return status;
 344 } /* command_handle */
 345
 346 /* initialize the connection state information */
 347 static int
 348 command_init(sdb_conn_t *conn)
 349 {
 350         const char *errmsg = NULL;
 351
 352         assert(conn && (conn->cmd == SDB_CONNECTION_IDLE) && (! conn->cmd_len));
 353
 354         if (conn->skip_len)
 355                 return -1;
 356
 357         /* reset */
 358         sdb_strbuf_clear(conn->errbuf);
 359
 360         conn->cmd = sdb_proto_get_int(conn->buf, 0);
 361         conn->cmd_len = sdb_proto_get_int(conn->buf, sizeof(uint32_t));
 362
 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
 466         sdb_object_deref(SDB_OBJ(conn));
 467 } /* sdb_connection_close */
 468
 469 ssize_t
 470 sdb_connection_read(sdb_conn_t *conn)
 471 {
 472         ssize_t n = 0;
 473
 474         sdb_conn_set_ctx(conn);
 475
 476         while (42) {
 477                 ssize_t status = connection_read(conn);
 478
 479                 if ((conn->cmd == SDB_CONNECTION_IDLE) && (! conn->cmd_len)
 480                                 && (sdb_strbuf_len(conn->buf) >= 2 * sizeof(int32_t)))
 481                         command_init(conn);
 482                 if ((conn->cmd != SDB_CONNECTION_IDLE)
 483                                 && (sdb_strbuf_len(conn->buf) >= conn->cmd_len)) {
 484                         command_handle(conn);
 485
 486                         /* remove the command from the buffer */
 487                         if (conn->cmd_len)
 488                                 sdb_strbuf_skip(conn->buf, 0, conn->cmd_len);
 489                         conn->cmd = SDB_CONNECTION_IDLE;
 490                         conn->cmd_len = 0;
 491                 }
 492
 493                 if (status <= 0)
 494                         break;
 495
 496                 n += status;
 497         }
 498
 499         sdb_conn_set_ctx(NULL);
 500         return n;
 501 } /* sdb_connection_read */
 502
 503 ssize_t
 504 sdb_connection_send(sdb_conn_t *conn, uint32_t code,
 505                 uint32_t msg_len, const char *msg)
 506 {
 507         char buf[2 * sizeof(uint32_t) + msg_len];
 508         ssize_t status;
 509
 510         if ((! conn) || (conn->fd < 0))
 511                 return -1;
 512         if (sdb_proto_marshal(buf, sizeof(buf), code, msg_len, msg) < 0)
 513                 return -1;
 514
 515         status = sdb_proto_send(conn->fd, sizeof(buf), buf);
 516         if (status < 0) {
 517                 char errbuf[1024];
 518
 519                 /* tell other code that there was a problem and, more importantly,
 520                  * make sure we don't try to send further logs to the connection */
 521                 close(conn->fd);
 522                 conn->fd = -1;
 523                 conn->ready = 0;
 524
 525                 sdb_log(SDB_LOG_ERR, "frontend: Failed to send msg "
 526                                 "(code: %u, len: %u) to client: %s", code, msg_len,
 527                                 sdb_strerror(errno, errbuf, sizeof(errbuf)));
 528         }
 529         return status;
 530 } /* sdb_connection_send */
 531
 532 int
 533 sdb_connection_ping(sdb_conn_t *conn)
 534 {
 535         if ((! conn) || (conn->cmd != SDB_CONNECTION_PING))
 536                 return -1;
 537
 538         /* we're alive */
 539         sdb_connection_send(conn, SDB_CONNECTION_OK, 0, NULL);
 540         return 0;
 541 } /* sdb_connection_ping */
 542
 543 /* vim: set tw=78 sw=4 ts=4 noexpandtab : */
 544