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 #include "sysdb.h"
  29 #include "core/object.h"
  30 #include "core/plugin.h"
  31 #include "frontend/connection-private.h"
  32 #include "utils/error.h"
  33 #include "utils/strbuf.h"
  34 #include "utils/proto.h"
  35
  36 #include <assert.h>
  37 #include <errno.h>
  38
  39 #include <arpa/inet.h>
  40 #include <fcntl.h>
  41
  42 #include <stdlib.h>
  43 #include <string.h>
  44
  45 #include <pthread.h>
  46
  47 /*
  48  * private variables
  49  */
  50
  51 static pthread_key_t conn_ctx_key;
  52 static _Bool         conn_ctx_key_initialized = 0;
  53
  54 /*
  55  * private types
  56  */
  57
  58 /* name of connection objects */
  59 #define CONN_FD_PREFIX "conn#"
  60 #define CONN_FD_PLACEHOLDER "XXXXXXX"
  61
  62 static int
  63 connection_init(sdb_object_t *obj, va_list ap)
  64 {
  65         sdb_conn_t *conn;
  66         int sock_fd;
  67         int sock_fl;
  68
  69         assert(obj);
  70         conn = CONN(obj);
  71
  72         sock_fd = va_arg(ap, int);
  73
  74         conn->buf = sdb_strbuf_create(/* size = */ 128);
  75         if (! conn->buf) {
  76                 sdb_log(SDB_LOG_ERR, "frontend: Failed to allocate a read buffer "
  77                                 "for a new connection");
  78                 return -1;
  79         }
  80         conn->errbuf = sdb_strbuf_create(0);
  81         if (! conn->errbuf) {
  82                 sdb_log(SDB_LOG_ERR, "frontend: Failed to allocate an error buffer "
  83                                 "for a new connection");
  84                 return -1;
  85         }
  86
  87         conn->client_addr_len = sizeof(conn->client_addr);
  88         conn->fd = accept(sock_fd, (struct sockaddr *)&conn->client_addr,
  89                         &conn->client_addr_len);
  90
  91         if (conn->fd < 0) {
  92                 char buf[1024];
  93                 sdb_log(SDB_LOG_ERR, "frontend: Failed to accept remote "
  94                                 "connection: %s", sdb_strerror(errno,
  95                                         buf, sizeof(buf)));
  96                 return -1;
  97         }
  98
  99         if (conn->client_addr.ss_family != AF_UNIX) {
 100                 sdb_log(SDB_LOG_ERR, "frontend: Accepted connection using "
 101                                 "unexpected family type %d", conn->client_addr.ss_family);
 102                 return -1;
 103         }
 104
 105         sock_fl = fcntl(conn->fd, F_GETFL);
 106         if (fcntl(conn->fd, F_SETFL, sock_fl | O_NONBLOCK)) {
 107                 char buf[1024];
 108                 sdb_log(SDB_LOG_ERR, "frontend: Failed to switch connection conn#%i "
 109                                 "to non-blocking mode: %s", conn->fd,
 110                                 sdb_strerror(errno, buf, sizeof(buf)));
 111                 return -1;
 112         }
 113
 114         sdb_log(SDB_LOG_DEBUG, "frontend: Accepted connection on fd=%i",
 115                         conn->fd);
 116
 117         conn->cmd = CONNECTION_IDLE;
 118         conn->cmd_len = 0;
 119         conn->skip_len = 0;
 120
 121         /* update the object name */
 122         snprintf(obj->name + strlen(CONN_FD_PREFIX),
 123                         strlen(CONN_FD_PLACEHOLDER), "%i", conn->fd);
 124         return 0;
 125 } /* connection_init */
 126
 127 static void
 128 connection_destroy(sdb_object_t *obj)
 129 {
 130         sdb_conn_t *conn;
 131         size_t len;
 132
 133         assert(obj);
 134         conn = CONN(obj);
 135
 136         if (conn->buf) {
 137                 len = sdb_strbuf_len(conn->buf);
 138                 if (len)
 139                         sdb_log(SDB_LOG_INFO, "frontend: Discarding incomplete command "
 140                                         "(%zu byte%s left in buffer)", len, len == 1 ? "" : "s");
 141         }
 142
 143         sdb_log(SDB_LOG_DEBUG, "frontend: Closing connection %s", obj->name);
 144         if (conn->fd >= 0)
 145                 close(conn->fd);
 146         conn->fd = -1;
 147
 148         if (conn->username)
 149                 free(conn->username);
 150         conn->username = NULL;
 151
 152         sdb_strbuf_destroy(conn->buf);
 153         conn->buf = NULL;
 154         sdb_strbuf_destroy(conn->errbuf);
 155         conn->errbuf = NULL;
 156 } /* connection_destroy */
 157
 158 static sdb_type_t connection_type = {
 159         /* size = */ sizeof(sdb_conn_t),
 160         /* init = */ connection_init,
 161         /* destroy = */ connection_destroy,
 162 };
 163
 164 /*
 165  * private helper functions
 166  */
 167
 168 static void
 169 sdb_conn_ctx_destructor(void *c)
 170 {
 171         sdb_object_t *conn = c;
 172
 173         if (! conn)
 174                 return;
 175         sdb_object_deref(conn);
 176 } /* sdb_conn_ctx_destructor */
 177
 178 static void
 179 sdb_conn_ctx_init(void)
 180 {
 181         if (conn_ctx_key_initialized)
 182                 return;
 183
 184         pthread_key_create(&conn_ctx_key, sdb_conn_ctx_destructor);
 185         conn_ctx_key_initialized = 1;
 186 } /* sdb_conn_ctx_init */
 187
 188 static void
 189 sdb_conn_set_ctx(sdb_conn_t *conn)
 190 {
 191         sdb_conn_t *old;
 192
 193         sdb_conn_ctx_init();
 194
 195         old = pthread_getspecific(conn_ctx_key);
 196         if (old)
 197                 sdb_object_deref(SDB_OBJ(old));
 198         if (conn)
 199                 sdb_object_ref(SDB_OBJ(conn));
 200         pthread_setspecific(conn_ctx_key, conn);
 201 } /* sdb_conn_set_ctx */
 202
 203 static sdb_conn_t *
 204 sdb_conn_get_ctx(void)
 205 {
 206         if (! conn_ctx_key_initialized)
 207                 return NULL;
 208         return pthread_getspecific(conn_ctx_key);
 209 } /* sdb_conn_get_ctx */
 210
 211 /*
 212  * connection handler functions
 213  */
 214
 215 /*
 216  * connection_log:
 217  * Send a log message originating from the current thread to the client.
 218  */
 219 static int
 220 connection_log(int prio, const char *msg,
 221                 sdb_object_t __attribute__((unused)) *user_data)
 222 {
 223         sdb_conn_t *conn;
 224
 225         conn = sdb_conn_get_ctx();
 226         /* no connection associated to this thread
 227          * or user not authenticated yet => don't leak any information */
 228         if ((! conn) || (! conn->username))
 229                 return 0;
 230
 231         /* XXX: make the log-level configurable by the client at runtime */
 232         if (prio >= SDB_LOG_DEBUG)
 233                 return 0;
 234
 235         /* TODO: Use CONNECTION_LOG_<prio>? */
 236         if (sdb_connection_send(conn, CONNECTION_LOG,
 237                                 (uint32_t)strlen(msg), msg) < 0)
 238                 return -1;
 239         return 0;
 240 } /* connection_log */
 241
 242 static uint32_t
 243 connection_get_int32(sdb_conn_t *conn, size_t offset)
 244 {
 245         const char *data;
 246         uint32_t n;
 247
 248         assert(conn && (sdb_strbuf_len(conn->buf) >= offset + sizeof(uint32_t)));
 249
 250         data = sdb_strbuf_string(conn->buf);
 251         memcpy(&n, data + offset, sizeof(n));
 252         n = ntohl(n);
 253         return n;
 254 } /* connection_get_int32 */
 255
 256 static int
 257 command_handle(sdb_conn_t *conn)
 258 {
 259         int status = -1;
 260
 261         assert(conn && (conn->cmd != CONNECTION_IDLE));
 262         assert(! conn->skip_len);
 263
 264         sdb_log(SDB_LOG_DEBUG, "frontend: Handling command %u (len: %u)",
 265                         conn->cmd, conn->cmd_len);
 266
 267         if (conn->cmd == CONNECTION_PING)
 268                 status = sdb_connection_ping(conn);
 269         else if (conn->cmd == CONNECTION_STARTUP)
 270                 status = sdb_fe_session_start(conn);
 271         else if (conn->cmd == CONNECTION_QUERY)
 272                 status = sdb_fe_query(conn);
 273         else if (conn->cmd == CONNECTION_FETCH)
 274                 status = sdb_fe_fetch(conn);
 275         else if (conn->cmd == CONNECTION_LIST)
 276                 status = sdb_fe_list(conn);
 277         else if (conn->cmd == CONNECTION_LOOKUP)
 278                 status = sdb_fe_lookup(conn);
 279         else {
 280                 sdb_log(SDB_LOG_WARNING, "frontend: Ignoring invalid command %#x",
 281                                 conn->cmd);
 282                 sdb_strbuf_sprintf(conn->errbuf, "Invalid command %#x", conn->cmd);
 283                 status = -1;
 284         }
 285
 286         if (status)
 287                 sdb_connection_send(conn, CONNECTION_ERROR,
 288                                 (uint32_t)sdb_strbuf_len(conn->errbuf),
 289                                 sdb_strbuf_string(conn->errbuf));
 290         return status;
 291 } /* command_handle */
 292
 293 /* initialize the connection state information */
 294 static int
 295 command_init(sdb_conn_t *conn)
 296 {
 297         const char *errmsg = NULL;
 298
 299         assert(conn && (conn->cmd == CONNECTION_IDLE) && (! conn->cmd_len));
 300
 301         if (conn->skip_len)
 302                 return -1;
 303
 304         /* reset */
 305         sdb_strbuf_clear(conn->errbuf);
 306
 307         conn->cmd = connection_get_int32(conn, 0);
 308         conn->cmd_len = connection_get_int32(conn, sizeof(uint32_t));
 309
 310         sdb_strbuf_skip(conn->buf, 0, 2 * sizeof(uint32_t));
 311
 312         if ((! conn->username) && (conn->cmd != CONNECTION_STARTUP))
 313                 errmsg = "Authentication required";
 314         else if (conn->cmd == CONNECTION_IDLE)
 315                 errmsg = "Invalid command 0";
 316
 317         if (errmsg) {
 318                 size_t len = sdb_strbuf_len(conn->buf);
 319
 320                 sdb_strbuf_sprintf(conn->errbuf, "%s", errmsg);
 321                 sdb_connection_send(conn, CONNECTION_ERROR,
 322                                 (uint32_t)strlen(errmsg), errmsg);
 323                 conn->skip_len += conn->cmd_len;
 324                 conn->cmd = CONNECTION_IDLE;
 325                 conn->cmd_len = 0;
 326
 327                 if (len > conn->skip_len)
 328                         len = conn->skip_len;
 329                 sdb_strbuf_skip(conn->buf, 0, len);
 330                 conn->skip_len -= len;
 331                 /* connection_read will handle anything else */
 332         }
 333         return 0;
 334 } /* command_init */
 335
 336 /* returns negative value on error, 0 on EOF, number of octets else */
 337 static ssize_t
 338 connection_read(sdb_conn_t *conn)
 339 {
 340         ssize_t n = 0;
 341
 342         if ((! conn) || (conn->fd < 0))
 343                 return -1;
 344
 345         while (42) {
 346                 ssize_t status;
 347
 348                 errno = 0;
 349                 status = sdb_strbuf_read(conn->buf, conn->fd, 1024);
 350                 if (status < 0) {
 351                         if ((errno == EAGAIN) || (errno == EWOULDBLOCK))
 352                                 break;
 353
 354                         close(conn->fd);
 355                         conn->fd = -1;
 356                         return (int)status;
 357                 }
 358                 else if (! status) /* EOF */
 359                         break;
 360
 361                 if (conn->skip_len) {
 362                         size_t len = (size_t)status < conn->skip_len
 363                                 ? (size_t)status : conn->skip_len;
 364                         sdb_strbuf_skip(conn->buf, 0, len);
 365                         conn->skip_len -= len;
 366                 }
 367
 368                 n += status;
 369
 370                 /* give the main loop a chance to execute commands (and free up buffer
 371                  * space) on large amounts of incoming traffic */
 372                 if (n > 1024 * 1024)
 373                         break;
 374         }
 375
 376         return n;
 377 } /* connection_read */
 378
 379 /*
 380  * public API
 381  */
 382
 383 int
 384 sdb_connection_enable_logging(void)
 385 {
 386         return sdb_plugin_register_log("connection-logger", connection_log,
 387                         /* user_data = */ NULL);
 388 } /* sdb_connection_enable_logging */
 389
 390 sdb_conn_t *
 391 sdb_connection_accept(int fd)
 392 {
 393         if (fd < 0)
 394                 return NULL;
 395
 396         /* the placeholder will be replaced with the accepted file
 397          * descriptor when initializing the object */
 398         return CONN(sdb_object_create(CONN_FD_PREFIX CONN_FD_PLACEHOLDER,
 399                                 connection_type, fd));
 400 } /* sdb_connection_create */
 401
 402 void
 403 sdb_connection_close(sdb_conn_t *conn)
 404 {
 405         if (! conn)
 406                 return;
 407
 408         /* close the connection even if someone else still references it */
 409         if (conn->fd >= 0)
 410                 close(conn->fd);
 411         conn->fd = -1;
 412
 413         sdb_object_deref(SDB_OBJ(conn));
 414 } /* sdb_connection_close */
 415
 416 ssize_t
 417 sdb_connection_read(sdb_conn_t *conn)
 418 {
 419         ssize_t n = 0;
 420
 421         sdb_conn_set_ctx(conn);
 422
 423         while (42) {
 424                 ssize_t status = connection_read(conn);
 425
 426                 if ((conn->cmd == CONNECTION_IDLE) && (! conn->cmd_len)
 427                                 && (sdb_strbuf_len(conn->buf) >= 2 * sizeof(int32_t)))
 428                         command_init(conn);
 429                 if ((conn->cmd != CONNECTION_IDLE)
 430                                 && (sdb_strbuf_len(conn->buf) >= conn->cmd_len)) {
 431                         command_handle(conn);
 432
 433                         /* remove the command from the buffer */
 434                         if (conn->cmd_len)
 435                                 sdb_strbuf_skip(conn->buf, 0, conn->cmd_len);
 436                         conn->cmd = CONNECTION_IDLE;
 437                         conn->cmd_len = 0;
 438                 }
 439
 440                 if (status <= 0)
 441                         break;
 442
 443                 n += status;
 444         }
 445
 446         sdb_conn_set_ctx(NULL);
 447         return n;
 448 } /* sdb_connection_read */
 449
 450 ssize_t
 451 sdb_connection_send(sdb_conn_t *conn, uint32_t code,
 452                 uint32_t msg_len, const char *msg)
 453 {
 454         ssize_t status;
 455
 456         if ((! conn) || (conn->fd < 0))
 457                 return -1;
 458
 459         status = sdb_proto_send_msg(conn->fd, code, msg_len, msg);
 460         if (status < 0) {
 461                 char errbuf[1024];
 462
 463                 /* tell other code that there was a problem and, more importantly,
 464                  * make sure we don't try to send further logs to the connection */
 465                 close(conn->fd);
 466                 conn->fd = -1;
 467
 468                 sdb_log(SDB_LOG_ERR, "frontend: Failed to send msg "
 469                                 "(code: %u, len: %u) to client: %s", code, msg_len,
 470                                 sdb_strerror(errno, errbuf, sizeof(errbuf)));
 471         }
 472         return status;
 473 } /* sdb_connection_send */
 474
 475 int
 476 sdb_connection_ping(sdb_conn_t *conn)
 477 {
 478         if ((! conn) || (conn->cmd != CONNECTION_PING))
 479                 return -1;
 480
 481         /* we're alive */
 482         sdb_connection_send(conn, CONNECTION_OK, 0, NULL);
 483         return 0;
 484 } /* sdb_connection_ping */
 485
 486 /* vim: set tw=78 sw=4 ts=4 noexpandtab : */
 487