src/child.c

   1 /* tinyproxy - A fast light-weight HTTP proxy
   2  * Copyright (C) 2000 Robert James Kaes <rjkaes@users.sourceforge.net>
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; either version 2 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License along
  15  * with this program; if not, write to the Free Software Foundation, Inc.,
  16  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  17  */
  18
  19 /* Handles the creation/destruction of the various children required for
  20  * processing incoming connections.
  21  */
  22
  23 #include "main.h"
  24
  25 #include "child.h"
  26 #include "daemon.h"
  27 #include "filter.h"
  28 #include "heap.h"
  29 #include "log.h"
  30 #include "reqs.h"
  31 #include "sock.h"
  32 #include "utils.h"
  33 #include "conf.h"
  34
  35 static int listenfd;
  36
  37 /*
  38  * Stores the internal data needed for each child (connection)
  39  */
  40 enum child_status_t { T_EMPTY, T_WAITING, T_CONNECTED };
  41 struct child_s {
  42         pid_t tid;
  43         unsigned int connects;
  44         enum child_status_t status;
  45 };
  46
  47 /*
  48  * A pointer to an array of children. A certain number of children are
  49  * created when the program is started.
  50  */
  51 static struct child_s *child_ptr;
  52
  53 static struct child_config_s {
  54         unsigned int maxclients, maxrequestsperchild;
  55         unsigned int maxspareservers, minspareservers, startservers;
  56 } child_config;
  57
  58 static unsigned int *servers_waiting;   /* servers waiting for a connection */
  59
  60 /*
  61  * Lock/Unlock the "servers_waiting" variable so that two children cannot
  62  * modify it at the same time.
  63  */
  64 #define SERVER_COUNT_LOCK()   _child_lock_wait()
  65 #define SERVER_COUNT_UNLOCK() _child_lock_release()
  66
  67 /* START OF LOCKING SECTION */
  68
  69 /*
  70  * These variables are required for the locking mechanism.  Also included
  71  * are the "private" functions for locking/unlocking.
  72  */
  73 static struct flock lock_it, unlock_it;
  74 static int lock_fd = -1;
  75
  76 static void _child_lock_init (void)
  77 {
  78         char lock_file[] = "/tmp/tinyproxy.servers.lock.XXXXXX";
  79
  80         /* Only allow u+rw bits. This may be required for some versions
  81          * of glibc so that mkstemp() doesn't make us vulnerable.
  82          */
  83         umask (0177);
  84
  85         lock_fd = mkstemp (lock_file);
  86         unlink (lock_file);
  87
  88         lock_it.l_type = F_WRLCK;
  89         lock_it.l_whence = SEEK_SET;
  90         lock_it.l_start = 0;
  91         lock_it.l_len = 0;
  92
  93         unlock_it.l_type = F_UNLCK;
  94         unlock_it.l_whence = SEEK_SET;
  95         unlock_it.l_start = 0;
  96         unlock_it.l_len = 0;
  97 }
  98
  99 static void _child_lock_wait (void)
 100 {
 101         int rc;
 102
 103         while ((rc = fcntl (lock_fd, F_SETLKW, &lock_it)) < 0) {
 104                 if (errno == EINTR)
 105                         continue;
 106                 else
 107                         return;
 108         }
 109 }
 110
 111 static void _child_lock_release (void)
 112 {
 113         if (fcntl (lock_fd, F_SETLKW, &unlock_it) < 0)
 114                 return;
 115 }
 116
 117 /* END OF LOCKING SECTION */
 118
 119 #define SERVER_INC() do { \
 120     SERVER_COUNT_LOCK(); \
 121     ++(*servers_waiting); \
 122     DEBUG2("INC: servers_waiting: %d", *servers_waiting); \
 123     SERVER_COUNT_UNLOCK(); \
 124 } while (0)
 125
 126 #define SERVER_DEC() do { \
 127     SERVER_COUNT_LOCK(); \
 128     assert(*servers_waiting > 0); \
 129     --(*servers_waiting); \
 130     DEBUG2("DEC: servers_waiting: %d", *servers_waiting); \
 131     SERVER_COUNT_UNLOCK(); \
 132 } while (0)
 133
 134 /*
 135  * Set the configuration values for the various child related settings.
 136  */
 137 short int child_configure (child_config_t type, unsigned int val)
 138 {
 139         switch (type) {
 140         case CHILD_MAXCLIENTS:
 141                 child_config.maxclients = val;
 142                 break;
 143         case CHILD_MAXSPARESERVERS:
 144                 child_config.maxspareservers = val;
 145                 break;
 146         case CHILD_MINSPARESERVERS:
 147                 child_config.minspareservers = val;
 148                 break;
 149         case CHILD_STARTSERVERS:
 150                 child_config.startservers = val;
 151                 break;
 152         case CHILD_MAXREQUESTSPERCHILD:
 153                 child_config.maxrequestsperchild = val;
 154                 break;
 155         default:
 156                 DEBUG2 ("Invalid type (%d)", type);
 157                 return -1;
 158         }
 159
 160         return 0;
 161 }
 162
 163 /**
 164  * child signal handler for sighup
 165  */
 166 static void child_sighup_handler (int sig)
 167 {
 168         if (sig == SIGHUP) {
 169                 /*
 170                  * Ignore the return value of reload_config for now.
 171                  * This should actually be handled somehow...
 172                  */
 173                 reload_config ();
 174
 175 #ifdef FILTER_ENABLE
 176                 filter_reload ();
 177 #endif /* FILTER_ENABLE */
 178         }
 179 }
 180
 181 /*
 182  * This is the main (per child) loop.
 183  */
 184 static void child_main (struct child_s *ptr)
 185 {
 186         int connfd;
 187         struct sockaddr *cliaddr;
 188         socklen_t clilen;
 189
 190         cliaddr = (struct sockaddr *)
 191                         safemalloc (sizeof(struct sockaddr_storage));
 192         if (!cliaddr) {
 193                 log_message (LOG_CRIT,
 194                              "Could not allocate memory for child address.");
 195                 exit (0);
 196         }
 197
 198         ptr->connects = 0;
 199
 200         while (!config.quit) {
 201                 ptr->status = T_WAITING;
 202
 203                 clilen = sizeof(struct sockaddr_storage);
 204
 205                 connfd = accept (listenfd, cliaddr, &clilen);
 206
 207 #ifndef NDEBUG
 208                 /*
 209                  * Enable the TINYPROXY_DEBUG environment variable if you
 210                  * want to use the GDB debugger.
 211                  */
 212                 if (getenv ("TINYPROXY_DEBUG")) {
 213                         /* Pause for 10 seconds to allow us to connect debugger */
 214                         fprintf (stderr,
 215                                  "Process has accepted connection: %ld\n",
 216                                  (long int) ptr->tid);
 217                         sleep (10);
 218                         fprintf (stderr, "Continuing process: %ld\n",
 219                                  (long int) ptr->tid);
 220                 }
 221 #endif
 222
 223                 /*
 224                  * Make sure no error occurred...
 225                  */
 226                 if (connfd < 0) {
 227                         log_message (LOG_ERR,
 228                                      "Accept returned an error (%s) ... retrying.",
 229                                      strerror (errno));
 230                         continue;
 231                 }
 232
 233                 ptr->status = T_CONNECTED;
 234
 235                 SERVER_DEC ();
 236
 237                 handle_connection (connfd);
 238                 ptr->connects++;
 239
 240                 if (child_config.maxrequestsperchild != 0) {
 241                         DEBUG2 ("%u connections so far...", ptr->connects);
 242
 243                         if (ptr->connects == child_config.maxrequestsperchild) {
 244                                 log_message (LOG_NOTICE,
 245                                              "Child has reached MaxRequestsPerChild (%u). "
 246                                              "Killing child.", ptr->connects);
 247                                 break;
 248                         }
 249                 }
 250
 251                 SERVER_COUNT_LOCK ();
 252                 if (*servers_waiting > child_config.maxspareservers) {
 253                         /*
 254                          * There are too many spare children, kill ourself
 255                          * off.
 256                          */
 257                         log_message (LOG_NOTICE,
 258                                      "Waiting servers (%d) exceeds MaxSpareServers (%d). "
 259                                      "Killing child.",
 260                                      *servers_waiting,
 261                                      child_config.maxspareservers);
 262                         SERVER_COUNT_UNLOCK ();
 263
 264                         break;
 265                 } else {
 266                         SERVER_COUNT_UNLOCK ();
 267                 }
 268
 269                 SERVER_INC ();
 270         }
 271
 272         ptr->status = T_EMPTY;
 273
 274         safefree (cliaddr);
 275         exit (0);
 276 }
 277
 278 /*
 279  * Fork a child "child" (or in our case a process) and then start up the
 280  * child_main() function.
 281  */
 282 static pid_t child_make (struct child_s *ptr)
 283 {
 284         pid_t pid;
 285
 286         if ((pid = fork ()) > 0)
 287                 return pid;     /* parent */
 288
 289         /*
 290          * Reset the SIGNALS so that the child can be reaped.
 291          */
 292         set_signal_handler (SIGCHLD, SIG_DFL);
 293         set_signal_handler (SIGTERM, SIG_DFL);
 294         set_signal_handler (SIGHUP, child_sighup_handler);
 295
 296         child_main (ptr);       /* never returns */
 297         return -1;
 298 }
 299
 300 /*
 301  * Create a pool of children to handle incoming connections
 302  */
 303 short int child_pool_create (void)
 304 {
 305         unsigned int i;
 306
 307         /*
 308          * Make sure the number of MaxClients is not zero, since this
 309          * variable determines the size of the array created for children
 310          * later on.
 311          */
 312         if (child_config.maxclients == 0) {
 313                 log_message (LOG_ERR,
 314                              "child_pool_create: \"MaxClients\" must be "
 315                              "greater than zero.");
 316                 return -1;
 317         }
 318         if (child_config.startservers == 0) {
 319                 log_message (LOG_ERR,
 320                              "child_pool_create: \"StartServers\" must be "
 321                              "greater than zero.");
 322                 return -1;
 323         }
 324
 325         child_ptr =
 326             (struct child_s *) calloc_shared_memory (child_config.maxclients,
 327                                                      sizeof (struct child_s));
 328         if (!child_ptr) {
 329                 log_message (LOG_ERR,
 330                              "Could not allocate memory for children.");
 331                 return -1;
 332         }
 333
 334         servers_waiting =
 335             (unsigned int *) malloc_shared_memory (sizeof (unsigned int));
 336         if (servers_waiting == MAP_FAILED) {
 337                 log_message (LOG_ERR,
 338                              "Could not allocate memory for child counting.");
 339                 return -1;
 340         }
 341         *servers_waiting = 0;
 342
 343         /*
 344          * Create a "locking" file for use around the servers_waiting
 345          * variable.
 346          */
 347         _child_lock_init ();
 348
 349         if (child_config.startservers > child_config.maxclients) {
 350                 log_message (LOG_WARNING,
 351                              "Can not start more than \"MaxClients\" servers. "
 352                              "Starting %u servers instead.",
 353                              child_config.maxclients);
 354                 child_config.startservers = child_config.maxclients;
 355         }
 356
 357         for (i = 0; i != child_config.maxclients; i++) {
 358                 child_ptr[i].status = T_EMPTY;
 359                 child_ptr[i].connects = 0;
 360         }
 361
 362         for (i = 0; i != child_config.startservers; i++) {
 363                 DEBUG2 ("Trying to create child %d of %d", i + 1,
 364                         child_config.startservers);
 365                 child_ptr[i].status = T_WAITING;
 366                 child_ptr[i].tid = child_make (&child_ptr[i]);
 367
 368                 if (child_ptr[i].tid < 0) {
 369                         log_message (LOG_WARNING,
 370                                      "Could not create child number %d of %d",
 371                                      i, child_config.startservers);
 372                         return -1;
 373                 } else {
 374                         log_message (LOG_INFO,
 375                                      "Creating child number %d of %d ...",
 376                                      i + 1, child_config.startservers);
 377
 378                         SERVER_INC ();
 379                 }
 380         }
 381
 382         log_message (LOG_INFO, "Finished creating all children.");
 383
 384         return 0;
 385 }
 386
 387 /*
 388  * Keep the proper number of servers running. This is the birth of the
 389  * servers. It monitors this at least once a second.
 390  */
 391 void child_main_loop (void)
 392 {
 393         unsigned int i;
 394
 395         while (1) {
 396                 if (config.quit)
 397                         return;
 398
 399                 /* If there are not enough spare servers, create more */
 400                 SERVER_COUNT_LOCK ();
 401                 if (*servers_waiting < child_config.minspareservers) {
 402                         log_message (LOG_NOTICE,
 403                                      "Waiting servers (%d) is less than MinSpareServers (%d). "
 404                                      "Creating new child.",
 405                                      *servers_waiting,
 406                                      child_config.minspareservers);
 407
 408                         SERVER_COUNT_UNLOCK ();
 409
 410                         for (i = 0; i != child_config.maxclients; i++) {
 411                                 if (child_ptr[i].status == T_EMPTY) {
 412                                         child_ptr[i].status = T_WAITING;
 413                                         child_ptr[i].tid =
 414                                             child_make (&child_ptr[i]);
 415                                         if (child_ptr[i].tid < 0) {
 416                                                 log_message (LOG_NOTICE,
 417                                                              "Could not create child");
 418
 419                                                 child_ptr[i].status = T_EMPTY;
 420                                                 break;
 421                                         }
 422
 423                                         SERVER_INC ();
 424
 425                                         break;
 426                                 }
 427                         }
 428                 } else {
 429                         SERVER_COUNT_UNLOCK ();
 430                 }
 431
 432                 sleep (5);
 433
 434                 /* Handle log rotation if it was requested */
 435                 if (received_sighup) {
 436                         /*
 437                          * Ignore the return value of reload_config for now.
 438                          * This should actually be handled somehow...
 439                          */
 440                         reload_config ();
 441
 442 #ifdef FILTER_ENABLE
 443                         filter_reload ();
 444 #endif /* FILTER_ENABLE */
 445
 446                         /* propagate filter reload to all children */
 447                         child_kill_children (SIGHUP);
 448
 449                         received_sighup = FALSE;
 450                 }
 451         }
 452 }
 453
 454 /*
 455  * Go through all the non-empty children and cancel them.
 456  */
 457 void child_kill_children (int sig)
 458 {
 459         unsigned int i;
 460
 461         for (i = 0; i != child_config.maxclients; i++) {
 462                 if (child_ptr[i].status != T_EMPTY)
 463                         kill (child_ptr[i].tid, sig);
 464         }
 465 }
 466
 467 int child_listening_sock (uint16_t port)
 468 {
 469         listenfd = listen_sock (config.ipAddr, port);
 470         return listenfd;
 471 }
 472
 473 void child_close_sock (void)
 474 {
 475         close (listenfd);
 476 }