webcit/context_loop.c

   1 /*
   2  * $Id$
   3  *
   4  * This is the other half of the webserver.  It handles the task of hooking
   5  * up HTTP requests with the sessions they belong to, using HTTP cookies to
   6  * keep track of things.  If the HTTP request doesn't belong to any currently
   7  * active session, a new session is started.
   8  *
   9  */
  10
  11 #include "webcit.h"
  12 #include "webserver.h"
  13
  14 /* Only one thread may manipulate SessionList at a time... */
  15 pthread_mutex_t SessionListMutex;
  16
  17 struct wcsession *SessionList = NULL; /**< our sessions ????*/
  18
  19 pthread_key_t MyConKey;         /**< TSD key for MySession() */
  20
  21
  22 /*
  23  * free the memory used for viewing atachments
  24  */
  25 void free_attachments(struct wcsession *sess) {
  26         struct wc_attachment *att;
  27
  28         while (sess->first_attachment != NULL) {
  29                 att = sess->first_attachment;
  30                 sess->first_attachment = sess->first_attachment->next;
  31                 free(att->data);
  32                 free(att);
  33         }
  34 }
  35
  36
  37 void shutdown_sessions(void)
  38 {
  39         struct wcsession *sptr;
  40
  41         for (sptr = SessionList; sptr != NULL; sptr = sptr->next) {
  42                         sptr->killthis = 1;
  43         }
  44 }
  45
  46 void do_housekeeping(void)
  47 {
  48         struct wcsession *sptr, *ss;
  49         struct wcsession *sessions_to_kill = NULL;
  50         int num_sessions = 0;
  51         static int num_threads = MIN_WORKER_THREADS;
  52
  53         /**
  54          * Lock the session list, moving any candidates for euthanasia into
  55          * a separate list.
  56          */
  57         pthread_mutex_lock(&SessionListMutex);
  58         num_sessions = 0;
  59         for (sptr = SessionList; sptr != NULL; sptr = sptr->next) {
  60                 ++num_sessions;
  61
  62                 /** Kill idle sessions */
  63                 if ((time(NULL) - (sptr->lastreq)) >
  64                    (time_t) WEBCIT_TIMEOUT) {
  65                         sptr->killthis = 1;
  66                 }
  67
  68                 /** Remove sessions flagged for kill */
  69                 if (sptr->killthis) {
  70
  71                         /** remove session from linked list */
  72                         if (sptr == SessionList) {
  73                                 SessionList = SessionList->next;
  74                         }
  75                         else for (ss=SessionList;ss!=NULL;ss=ss->next) {
  76                                 if (ss->next == sptr) {
  77                                         ss->next = ss->next->next;
  78                                 }
  79                         }
  80
  81                         sptr->next = sessions_to_kill;
  82                         sessions_to_kill = sptr;
  83                 }
  84         }
  85         pthread_mutex_unlock(&SessionListMutex);
  86
  87         /**
  88          * Now free up and destroy the culled sessions.
  89          */
  90         while (sessions_to_kill != NULL) {
  91                 lprintf(3, "Destroying session %d\n", sessions_to_kill->wc_session);
  92                 pthread_mutex_lock(&sessions_to_kill->SessionMutex);
  93                 close(sessions_to_kill->serv_sock);
  94                 close(sessions_to_kill->chat_sock);
  95 //              if (sessions_to_kill->preferences != NULL) {
  96 //                      free(sessions_to_kill->preferences);
  97 //              }
  98                 if (sessions_to_kill->cache_fold != NULL) {
  99                         free(sessions_to_kill->cache_fold);
 100                 }
 101                 free_attachments(sessions_to_kill);
 102                 free_march_list(sessions_to_kill);
 103                 DeleteHash(&(sessions_to_kill->hash_prefs));
 104                 DeleteHash(&(sessions_to_kill->IconBarSetttings));
 105                 FreeStrBuf(&(sessions_to_kill->UrlFragment1));
 106                 FreeStrBuf(&(sessions_to_kill->UrlFragment2));
 107                 FreeStrBuf(&(sessions_to_kill->WBuf));
 108
 109                 pthread_mutex_unlock(&sessions_to_kill->SessionMutex);
 110                 sptr = sessions_to_kill->next;
 111                 free(sessions_to_kill);
 112                 sessions_to_kill = sptr;
 113                 --num_sessions;
 114         }
 115
 116         /**
 117          * If there are more sessions than threads, then we should spawn
 118          * more threads ... up to a predefined maximum.
 119          */
 120         while ( (num_sessions > num_threads)
 121               && (num_threads <= MAX_WORKER_THREADS) ) {
 122                 spawn_another_worker_thread();
 123                 ++num_threads;
 124                 lprintf(3, "There are %d sessions and %d threads active.\n",
 125                         num_sessions, num_threads);
 126         }
 127 }
 128
 129
 130 /**
 131  * \brief Wake up occasionally and clean house
 132  */
 133 void housekeeping_loop(void)
 134 {
 135         while (1) {
 136                 sleeeeeeeeeep(HOUSEKEEPING);
 137                 do_housekeeping();
 138         }
 139 }
 140
 141
 142 /**
 143  * \brief Create a Session id
 144  * Generate a unique WebCit session ID (which is not the same thing as the
 145  * Citadel session ID).
 146  *
 147  * \todo FIXME ... ensure that session number is truly unique
 148  *
 149  */
 150 int GenerateSessionID(void)
 151 {
 152         static int seq = (-1);
 153
 154         if (seq < 0) {
 155                 seq = (int) time(NULL);
 156         }
 157
 158         return ++seq;
 159 }
 160
 161
 162 /*
 163  * Collapse multiple cookies on one line
 164  */
 165 int req_gets(int sock, char *buf, char *hold, size_t hlen)
 166 {
 167         int a, b;
 168
 169         if (IsEmptyStr(hold)) {
 170                 strcpy(buf, "");
 171                 a = client_getln(sock, buf, SIZ);
 172                 if (a<1) return(-1);
 173         } else {
 174                 safestrncpy(buf, hold, SIZ);
 175         }
 176         strcpy(hold, "");
 177
 178         if (!strncasecmp(buf, "Cookie: ", 8)) {
 179                 int len;
 180                 len = strlen(buf);
 181                 for (a = 0; a < len; ++a)
 182                         if (buf[a] == ';') {
 183                                 // we don't refresh len, because of we
 184                                 // only exit from here.
 185                                 snprintf(hold, hlen, "Cookie: %s", &buf[a + 1]);
 186                                 buf[a] = 0;
 187                                 b = 8;
 188                                 while (isspace(hold[b]))
 189                                         b++;
 190
 191                                 memmove(&hold[8], &hold[b], len - b + 1);
 192                                 return(0);
 193                         }
 194         }
 195
 196         return(0);
 197 }
 198
 199 /*
 200  * lingering_close() a`la Apache. see
 201  * http://www.apache.org/docs/misc/fin_wait_2.html for rationale
 202  */
 203 int lingering_close(int fd)
 204 {
 205         char buf[SIZ];
 206         int i;
 207         fd_set set;
 208         struct timeval tv, start;
 209
 210         gettimeofday(&start, NULL);
 211         shutdown(fd, 1);
 212         do {
 213                 do {
 214                         gettimeofday(&tv, NULL);
 215                         tv.tv_sec = SLEEPING - (tv.tv_sec - start.tv_sec);
 216                         tv.tv_usec = start.tv_usec - tv.tv_usec;
 217                         if (tv.tv_usec < 0) {
 218                                 tv.tv_sec--;
 219                                 tv.tv_usec += 1000000;
 220                         }
 221                         FD_ZERO(&set);
 222                         FD_SET(fd, &set);
 223                         i = select(fd + 1, &set, NULL, NULL, &tv);
 224                 } while (i == -1 && errno == EINTR);
 225
 226                 if (i <= 0)
 227                         break;
 228
 229                 i = read(fd, buf, sizeof buf);
 230         } while (i != 0 && (i != -1 || errno == EINTR));
 231
 232         return close(fd);
 233 }
 234
 235
 236
 237 /**
 238  * \brief       sanity requests
 239  *              Check for bogus requests coming from brain-dead Windows boxes.
 240  *
 241  * \param       http_cmd        The HTTP request to check
 242  */
 243 int is_bogus(char *http_cmd) {
 244         char *url;
 245         int i, max;
 246
 247         url = strstr(http_cmd, " ");
 248         if (url == NULL) return(1);
 249         ++url;
 250
 251         char *bogus_prefixes[] = {
 252                 "/scripts/root.exe",    /**< Worms and trojans and viruses, oh my! */
 253                 "/c/winnt",
 254                 "/MSADC/",
 255                 "/_vti",                /**< Broken Microsoft DAV implementation */
 256                 "/MSOffice"             /**< Stoopid MSOffice thinks everyone is IIS */
 257         };
 258
 259         max = sizeof(bogus_prefixes) / sizeof(char *);
 260
 261         for (i=0; i<max; ++i) {
 262                 if (!strncasecmp(url, bogus_prefixes[i], strlen(bogus_prefixes[i]))) {
 263                         return(2);
 264                 }
 265         }
 266
 267         return(0);      /* probably ok */
 268 }
 269
 270
 271
 272 /**
 273  * \brief handle one request
 274  * This loop gets called once for every HTTP connection made to WebCit.  At
 275  * this entry point we have an HTTP socket with a browser allegedly on the
 276  * other end, but we have not yet bound to a WebCit session.
 277  *
 278  * The job of this function is to locate the correct session and bind to it,
 279  * or create a session if necessary and bind to it, then run the WebCit
 280  * transaction loop.  Afterwards, we unbind from the session.  When this
 281  * function returns, the worker thread is then free to handle another
 282  * transaction.
 283  * \param sock the socket we will put our answer to
 284  */
 285 void context_loop(int sock)
 286 {
 287         struct httprequest *req = NULL;
 288         struct httprequest *last = NULL;
 289         struct httprequest *hptr;
 290         char buf[SIZ], hold[SIZ];
 291         int desired_session = 0;
 292         int got_cookie = 0;
 293         int gzip_ok = 0;
 294         struct wcsession *TheSession, *sptr;
 295         char httpauth_string[1024];
 296         char httpauth_user[1024];
 297         char httpauth_pass[1024];
 298         char accept_language[256];
 299         char *ptr = NULL;
 300         int session_is_new = 0;
 301
 302         strcpy(httpauth_string, "");
 303         strcpy(httpauth_user, DEFAULT_HTTPAUTH_USER);
 304         strcpy(httpauth_pass, DEFAULT_HTTPAUTH_PASS);
 305
 306         /**
 307          * Find out what it is that the web browser is asking for
 308          */
 309         memset(hold, 0, sizeof(hold));
 310         do {
 311                 if (req_gets(sock, buf, hold, SIZ) < 0) return;
 312
 313                 /**
 314                  * Can we compress?
 315                  */
 316                 if (!strncasecmp(buf, "Accept-encoding:", 16)) {
 317                         if (strstr(&buf[16], "gzip")) {
 318                                 gzip_ok = 1;
 319                         }
 320                 }
 321
 322                 /**
 323                  * Browser-based sessions use cookies for session authentication
 324                  */
 325                 if (!strncasecmp(buf, "Cookie: webcit=", 15)) {
 326                         cookie_to_stuff(&buf[15], &desired_session,
 327                                 NULL, 0, NULL, 0, NULL, 0);
 328                         got_cookie = 1;
 329                 }
 330
 331                 /**
 332                  * GroupDAV-based sessions use HTTP authentication
 333                  */
 334                 if (!strncasecmp(buf, "Authorization: Basic ", 21)) {
 335                         CtdlDecodeBase64(httpauth_string, &buf[21], strlen(&buf[21]));
 336                         extract_token(httpauth_user, httpauth_string, 0, ':', sizeof httpauth_user);
 337                         extract_token(httpauth_pass, httpauth_string, 1, ':', sizeof httpauth_pass);
 338                 }
 339
 340                 if (!strncasecmp(buf, "If-Modified-Since: ", 19)) {
 341                         if_modified_since = httpdate_to_timestamp(&buf[19]);
 342                 }
 343
 344                 if (!strncasecmp(buf, "Accept-Language: ", 17)) {
 345                         safestrncpy(accept_language, &buf[17], sizeof accept_language);
 346                 }
 347
 348                 /**
 349                  * Read in the request
 350                  */
 351                 hptr = (struct httprequest *)
 352                         malloc(sizeof(struct httprequest));
 353                 if (req == NULL)
 354                         req = hptr;
 355                 else
 356                         last->next = hptr;
 357                 hptr->next = NULL;
 358                 last = hptr;
 359
 360                 safestrncpy(hptr->line, buf, sizeof hptr->line);
 361
 362         } while (!IsEmptyStr(buf));
 363
 364         /**
 365          * If the request is prefixed by "/webcit" then chop that off.  This
 366          * allows a front end web server to forward all /webcit requests to us
 367          * while still using the same web server port for other things.
 368          */
 369
 370         ptr = strstr(req->line, " /webcit ");   /*< Handle "/webcit" */
 371         if (ptr != NULL) {
 372                 strcpy(ptr+2, ptr+8);
 373         }
 374
 375         ptr = strstr(req->line, " /webcit");    /*< Handle "/webcit/" */
 376         if (ptr != NULL) {
 377                 strcpy(ptr+1, ptr+8);
 378         }
 379
 380         /** Begin parsing the request. */
 381
 382         safestrncpy(buf, req->line, sizeof buf);
 383         lprintf(5, "HTTP: %s\n", buf);
 384
 385         /** Check for bogus requests */
 386         if (is_bogus(buf)) {
 387                 strcpy(req->line, "GET /404 HTTP/1.1");
 388                 strcpy(buf, "GET /404 HTTP/1.1");
 389         }
 390
 391         /**
 392          * Strip out the method, leaving the URL up front...
 393          */
 394         remove_token(buf, 0, ' ');
 395         if (buf[1]==' ') buf[1]=0;
 396
 397         /**
 398          * While we're at it, gracefully handle requests for the
 399          * robots.txt and favicon.ico files.
 400          */
 401         if (!strncasecmp(buf, "/robots.txt", 11)) {
 402                 strcpy(req->line, "GET /static/robots.txt"
 403                                 "?force_close_session=yes HTTP/1.1");
 404         }
 405         else if (!strncasecmp(buf, "/favicon.ico", 12)) {
 406                 strcpy(req->line, "GET /static/favicon.ico");
 407         }
 408
 409         /**
 410          * These are the URL's which may be executed without a
 411          * session cookie already set.  If it's not one of these,
 412          * force the session to close because cookies are
 413          * probably disabled on the client browser.
 414          */
 415         else if ( (strcmp(buf, "/"))
 416                 && (strncasecmp(buf, "/listsub", 8))
 417                 && (strncasecmp(buf, "/freebusy", 9))
 418                 && (strncasecmp(buf, "/do_logout", 10))
 419                 && (strncasecmp(buf, "/groupdav", 9))
 420                 && (strncasecmp(buf, "/static", 7))
 421                 && (strncasecmp(buf, "/rss", 4))
 422                 && (strncasecmp(buf, "/404", 4))
 423                 && (got_cookie == 0)) {
 424                 strcpy(req->line, "GET /static/nocookies.html"
 425                                 "?force_close_session=yes HTTP/1.1");
 426         }
 427
 428         /**
 429          * See if there's an existing session open with the desired ID or user/pass
 430          */
 431         TheSession = NULL;
 432
 433         if (TheSession == NULL) {
 434                 pthread_mutex_lock(&SessionListMutex);
 435                 for (sptr = SessionList; sptr != NULL; sptr = sptr->next) {
 436
 437                         /** If HTTP-AUTH, look for a session with matching credentials */
 438                         if ( (!IsEmptyStr(httpauth_user))
 439                            &&(!strcasecmp(sptr->httpauth_user, httpauth_user))
 440                            &&(!strcasecmp(sptr->httpauth_pass, httpauth_pass)) ) {
 441                                 TheSession = sptr;
 442                         }
 443
 444                         /** If cookie-session, look for a session with matching session ID */
 445                         if ( (desired_session != 0) && (sptr->wc_session == desired_session)) {
 446                                 TheSession = sptr;
 447                         }
 448
 449                 }
 450                 pthread_mutex_unlock(&SessionListMutex);
 451         }
 452
 453         /**
 454          * Create a new session if we have to
 455          */
 456         if (TheSession == NULL) {
 457                 lprintf(3, "Creating a new session\n");
 458                 TheSession = (struct wcsession *)
 459                         malloc(sizeof(struct wcsession));
 460                 memset(TheSession, 0, sizeof(struct wcsession));
 461                 TheSession->serv_sock = (-1);
 462                 TheSession->chat_sock = (-1);
 463
 464                 /* If we're recreating a session that expired, it's best to give it the same
 465                  * session number that it had before.  The client browser ought to pick up
 466                  * the new session number and start using it, but in some rare situations it
 467                  * doesn't, and that's a Bad Thing because it causes lots of spurious sessions
 468                  * to get created.
 469                  */
 470                 if (desired_session == 0) {
 471                         TheSession->wc_session = GenerateSessionID();
 472                 }
 473                 else {
 474                         TheSession->wc_session = desired_session;
 475                 }
 476
 477                 strcpy(TheSession->httpauth_user, httpauth_user);
 478                 strcpy(TheSession->httpauth_pass, httpauth_pass);
 479                 TheSession->hash_prefs = NewHash(1,NULL);       /* Get a hash table for the user preferences */
 480                 pthread_mutex_init(&TheSession->SessionMutex, NULL);
 481                 pthread_mutex_lock(&SessionListMutex);
 482                 TheSession->urlstrings = NULL;
 483                 TheSession->vars = NULL;
 484                 TheSession->nonce = rand();
 485                 TheSession->next = SessionList;
 486                 SessionList = TheSession;
 487                 pthread_mutex_unlock(&SessionListMutex);
 488                 session_is_new = 1;
 489         }
 490
 491         /*
 492          * A future improvement might be to check the session integrity
 493          * at this point before continuing.
 494          */
 495
 496         /*
 497          * Bind to the session and perform the transaction
 498          */
 499         pthread_mutex_lock(&TheSession->SessionMutex);          /* bind */
 500         pthread_setspecific(MyConKey, (void *)TheSession);
 501
 502         TheSession->urlstrings = NewHash(1,NULL);
 503         TheSession->vars = NewHash(1,NULL);
 504         TheSession->http_sock = sock;
 505         TheSession->lastreq = time(NULL);                       /* log */
 506         TheSession->gzip_ok = gzip_ok;
 507 #ifdef ENABLE_NLS
 508         if (session_is_new) {
 509                 httplang_to_locale(accept_language);
 510         }
 511         go_selected_language();                                 /* set locale */
 512 #endif
 513         session_loop(req);                                      /* do transaction */
 514 #ifdef ENABLE_NLS
 515         stop_selected_language();                               /* unset locale */
 516 #endif
 517         DeleteHash(&TheSession->urlstrings);
 518         DeleteHash(&TheSession->vars);
 519
 520         pthread_mutex_unlock(&TheSession->SessionMutex);        /* unbind */
 521
 522         /* Free the request buffer */
 523         while (req != NULL) {
 524                 hptr = req->next;
 525                 free(req);
 526                 req = hptr;
 527         }
 528
 529         /*
 530          * Free up any session-local substitution variables which
 531          * were set during this transaction
 532          */
 533
 534
 535 }