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 #include "modules_init.h"
  14
  15 /* Only one thread may manipulate SessionList at a time... */
  16 pthread_mutex_t SessionListMutex;
  17
  18 wcsession *SessionList = NULL; /**< our sessions ????*/
  19
  20 pthread_key_t MyConKey;         /**< TSD key for MySession() */
  21 HashList *HttpReqTypes = NULL;
  22
  23 void shutdown_sessions(void)
  24 {
  25         wcsession *sptr;
  26
  27         for (sptr = SessionList; sptr != NULL; sptr = sptr->next) {
  28                         sptr->killthis = 1;
  29         }
  30 }
  31
  32 void do_housekeeping(void)
  33 {
  34         wcsession *sptr, *ss;
  35         wcsession *sessions_to_kill = NULL;
  36         int num_sessions = 0;
  37         static int num_threads = MIN_WORKER_THREADS;
  38
  39         /**
  40          * Lock the session list, moving any candidates for euthanasia into
  41          * a separate list.
  42          */
  43         pthread_mutex_lock(&SessionListMutex);
  44         num_sessions = 0;
  45         for (sptr = SessionList; sptr != NULL; sptr = sptr->next) {
  46                 ++num_sessions;
  47
  48                 /** Kill idle sessions */
  49                 if ((time(NULL) - (sptr->lastreq)) >
  50                    (time_t) WEBCIT_TIMEOUT) {
  51                         sptr->killthis = 1;
  52                 }
  53
  54                 /** Remove sessions flagged for kill */
  55                 if (sptr->killthis) {
  56
  57                         /** remove session from linked list */
  58                         if (sptr == SessionList) {
  59                                 SessionList = SessionList->next;
  60                         }
  61                         else for (ss=SessionList;ss!=NULL;ss=ss->next) {
  62                                 if (ss->next == sptr) {
  63                                         ss->next = ss->next->next;
  64                                 }
  65                         }
  66
  67                         sptr->next = sessions_to_kill;
  68                         sessions_to_kill = sptr;
  69                 }
  70         }
  71         pthread_mutex_unlock(&SessionListMutex);
  72
  73         /**
  74          * Now free up and destroy the culled sessions.
  75          */
  76         while (sessions_to_kill != NULL) {
  77                 lprintf(3, "Destroying session %d\n", sessions_to_kill->wc_session);
  78                 pthread_mutex_lock(&sessions_to_kill->SessionMutex);
  79                 pthread_mutex_unlock(&sessions_to_kill->SessionMutex);
  80                 sptr = sessions_to_kill->next;
  81
  82                 session_destroy_modules(&sessions_to_kill);
  83                 sessions_to_kill = sptr;
  84                 --num_sessions;
  85         }
  86
  87         /**
  88          * If there are more sessions than threads, then we should spawn
  89          * more threads ... up to a predefined maximum.
  90          */
  91         while ( (num_sessions > num_threads)
  92               && (num_threads <= MAX_WORKER_THREADS) ) {
  93                 spawn_another_worker_thread();
  94                 ++num_threads;
  95                 lprintf(3, "There are %d sessions and %d threads active.\n",
  96                         num_sessions, num_threads);
  97         }
  98 }
  99
 100
 101 /*
 102  * Wake up occasionally and clean house
 103  */
 104 void housekeeping_loop(void)
 105 {
 106         while (1) {
 107                 sleeeeeeeeeep(HOUSEKEEPING);
 108                 do_housekeeping();
 109         }
 110 }
 111
 112
 113 /*
 114  * Create a Session id
 115  * Generate a unique WebCit session ID (which is not the same thing as the
 116  * Citadel session ID).
 117  */
 118 int GenerateSessionID(void)
 119 {
 120         static int seq = (-1);
 121
 122         if (seq < 0) {
 123                 seq = (int) time(NULL);
 124         }
 125
 126         return ++seq;
 127 }
 128
 129
 130 /*
 131  * lingering_close() a`la Apache. see
 132  * http://www.apache.org/docs/misc/fin_wait_2.html for rationale
 133  */
 134 int lingering_close(int fd)
 135 {
 136         char buf[SIZ];
 137         int i;
 138         fd_set set;
 139         struct timeval tv, start;
 140
 141         gettimeofday(&start, NULL);
 142         shutdown(fd, 1);
 143         do {
 144                 do {
 145                         gettimeofday(&tv, NULL);
 146                         tv.tv_sec = SLEEPING - (tv.tv_sec - start.tv_sec);
 147                         tv.tv_usec = start.tv_usec - tv.tv_usec;
 148                         if (tv.tv_usec < 0) {
 149                                 tv.tv_sec--;
 150                                 tv.tv_usec += 1000000;
 151                         }
 152                         FD_ZERO(&set);
 153                         FD_SET(fd, &set);
 154                         i = select(fd + 1, &set, NULL, NULL, &tv);
 155                 } while (i == -1 && errno == EINTR);
 156
 157                 if (i <= 0)
 158                         break;
 159
 160                 i = read(fd, buf, sizeof buf);
 161         } while (i != 0 && (i != -1 || errno == EINTR));
 162
 163         return close(fd);
 164 }
 165
 166
 167
 168 /*
 169  * Look for commonly-found probes of malware such as worms, viruses, trojans, and Microsoft Office.
 170  * Short-circuit these requests so we don't have to send them through the full processing loop.
 171  */
 172 int is_bogus(StrBuf *http_cmd) {
 173         const char *url;
 174         int i, max;
 175         const char *bogus_prefixes[] = {
 176                 "/scripts/root.exe",    /* Worms and trojans and viruses, oh my! */
 177                 "/c/winnt",
 178                 "/MSADC/",
 179                 "/_vti",                /* Broken Microsoft DAV implementation */
 180                 "/MSOffice",            /* Stoopid MSOffice thinks everyone is IIS */
 181                 "/nonexistenshit"       /* Exploit found in the wild January 2009 */
 182         };
 183
 184         url = ChrPtr(http_cmd);
 185         if (IsEmptyStr(url)) return(1);
 186         ++url;
 187
 188         max = sizeof(bogus_prefixes) / sizeof(char *);
 189
 190         for (i=0; i<max; ++i) {
 191                 if (!strncasecmp(url, bogus_prefixes[i], strlen(bogus_prefixes[i]))) {
 192                         return(2);
 193                 }
 194         }
 195
 196         return(0);      /* probably ok */
 197 }
 198
 199
 200 /*const char *nix(void *vptr) {return ChrPtr( (StrBuf*)vptr);}*/
 201
 202 /*
 203  * handle one request
 204  *
 205  * This loop gets called once for every HTTP connection made to WebCit.  At
 206  * this entry point we have an HTTP socket with a browser allegedly on the
 207  * other end, but we have not yet bound to a WebCit session.
 208  *
 209  * The job of this function is to locate the correct session and bind to it,
 210  * or create a session if necessary and bind to it, then run the WebCit
 211  * transaction loop.  Afterwards, we unbind from the session.  When this
 212  * function returns, the worker thread is then free to handle another
 213  * transaction.
 214  */
 215 void context_loop(int *sock)
 216 {
 217         long eReqType = eGET;
 218         int isbogus = 0;
 219         const char *Pos = NULL;
 220         const char *buf;
 221         int desired_session = 0;
 222         int got_cookie = 0;
 223         int gzip_ok = 0;
 224         wcsession *TheSession, *sptr;
 225         char httpauth_string[1024];
 226         char httpauth_user[1024];
 227         char httpauth_pass[1024];
 228         int nLine = 0;
 229         int LineLen;
 230         void *vLine;
 231         StrBuf *Buf, *Line, *LastLine, *HeaderName, *ReqLine;
 232         const char *pch, *pchs, *pche;
 233         HashList *HTTPHeaders;
 234
 235         strcpy(httpauth_string, "");
 236         strcpy(httpauth_user, DEFAULT_HTTPAUTH_USER);
 237         strcpy(httpauth_pass, DEFAULT_HTTPAUTH_PASS);
 238
 239         /*
 240          * Find out what it is that the web browser is asking for
 241          */
 242         HeaderName = NewStrBuf();
 243         Buf = NewStrBuf();
 244         LastLine = NULL;
 245         HTTPHeaders = NewHash(1, NULL);
 246
 247         /*
 248          * Read in the request
 249          */
 250         do {
 251                 nLine ++;
 252                 Line = NewStrBuf();
 253
 254
 255                 if (ClientGetLine(sock, Line, Buf, &Pos) < 0) return;
 256
 257                 LineLen = StrLength(Line);
 258
 259                 if (nLine == 1) {
 260                         ReqLine = Line;
 261                         /* The requesttype... GET, POST... */
 262                         StrBufExtract_token(HeaderName, ReqLine, 0, ' ');
 263                         if (GetHash(HttpReqTypes, SKEY(HeaderName), &vLine) &&
 264                             (vLine != NULL))
 265                         {
 266                                 eReqType = *(long*)vLine;
 267                         }
 268                         else {
 269                                 eReqType = eGET;
 270                                 isbogus = 1;
 271                                 break;
 272                         }
 273                         StrBufCutLeft(ReqLine, StrLength(HeaderName) + 1);
 274                         /* the HTTP Version... */
 275                         StrBufExtract_token(HeaderName, ReqLine, 1, ' ');
 276                         StrBufCutRight(ReqLine, StrLength(HeaderName) + 1);
 277                         if ((StrLength(HeaderName) == 0) ||
 278                             is_bogus(ReqLine)) {
 279                                 eReqType = eGET;
 280                                 isbogus = 1;
 281                                 break;
 282                         }
 283                         continue;
 284                 }
 285                 if (LineLen == 0) {
 286                         FreeStrBuf(&Line);
 287                         continue;
 288                 }
 289
 290                 /* Do we need to Unfold? */
 291                 if ((LastLine != NULL) &&
 292                     (isspace(*ChrPtr(Line)))) {
 293                         pch = pchs = ChrPtr(Line);
 294                         pche = pchs + StrLength(Line);
 295                         while (isspace(*pch) && (pch < pche))
 296                                 pch ++;
 297                         StrBufCutLeft(Line, pch - pchs);
 298                         StrBufAppendBuf(LastLine, Line, 0);
 299                         FreeStrBuf(&Line);
 300                         continue;
 301                 }
 302
 303                 StrBufSanitizeAscii(Line, '§');
 304                 StrBufExtract_token(HeaderName, Line, 0, ':');
 305
 306                 pchs = ChrPtr(Line);
 307                 pch = pchs + StrLength(HeaderName) + 1;
 308                 pche = pchs + StrLength(Line);
 309                 while (isspace(*pch) && (pch < pche))
 310                         pch ++;
 311                 StrBufCutLeft(Line, pch - pchs);
 312
 313                 StrBufUpCase(HeaderName);
 314                 Put(HTTPHeaders, SKEY(HeaderName), Line, HFreeStrBuf);
 315                 LastLine = Line;
 316         } while (LineLen > 0);
 317
 318         FreeStrBuf(&HeaderName);
 319
 320         if (isbogus)
 321                 StrBufPlain(ReqLine, HKEY("/404"));
 322
 323
 324 /*      dbg_PrintHash(HTTPHeaders, nix, NULL);  */
 325
 326
 327         /*
 328          * Can we compress?
 329          */
 330         if (!isbogus &&
 331             GetHash(HTTPHeaders, HKEY("ACCEPT-ENCODING"), &vLine) &&
 332             (vLine != NULL)) {
 333                 buf = ChrPtr((StrBuf*)vLine);
 334                 if (strstr(&buf[16], "gzip")) {
 335                         gzip_ok = 1;
 336                 }
 337         }
 338
 339         /*
 340          * Browser-based sessions use cookies for session authentication
 341          */
 342         if (!isbogus &&
 343             GetHash(HTTPHeaders, HKEY("COOKIE"), &vLine) &&
 344             (vLine != NULL)) {
 345                 cookie_to_stuff(vLine, &desired_session,
 346                                 NULL, NULL, NULL);
 347                 got_cookie = 1;
 348         }
 349
 350         /*
 351          * GroupDAV-based sessions use HTTP authentication
 352          */
 353         if (!isbogus &&
 354             GetHash(HTTPHeaders, HKEY("AUTHORIZATION"), &vLine) &&
 355             (vLine != NULL)) {
 356                 Line = (StrBuf*)vLine;
 357                 if (strncasecmp(ChrPtr(Line), "Basic", 5) == 0) {
 358                         StrBufCutLeft(Line, 6);
 359                         CtdlDecodeBase64(httpauth_string, ChrPtr(Line), StrLength(Line));
 360                         extract_token(httpauth_user, httpauth_string, 0, ':', sizeof httpauth_user);
 361                         extract_token(httpauth_pass, httpauth_string, 1, ':', sizeof httpauth_pass);
 362                 }
 363                 else
 364                         lprintf(1, "Authentication scheme not supported! [%s]\n", ChrPtr(Line));
 365         }
 366
 367         if (!isbogus &&
 368             GetHash(HTTPHeaders, HKEY("IF-MODIFIED-SINCE"), &vLine) &&
 369             (vLine != NULL)) {
 370                 if_modified_since = httpdate_to_timestamp((StrBuf*)vLine);
 371         }
 372
 373
 374
 375
 376         /*
 377          * If the request is prefixed by "/webcit" then chop that off.  This
 378          * allows a front end web server to forward all /webcit requests to us
 379          * while still using the same web server port for other things.
 380          */
 381         if (!isbogus &&
 382             (StrLength(ReqLine) >= 8) &&
 383             (strstr(ChrPtr(ReqLine), "/webcit/")) ) {
 384                 StrBufCutLeft(ReqLine, 7);
 385         }
 386
 387         /* Begin parsing the request. */
 388 #ifdef TECH_PREVIEW
 389         if ((strncmp(ChrPtr(ReqLine), "/sslg", 5) != 0) &&
 390             (strncmp(ChrPtr(ReqLine), "/static/", 8) != 0) &&
 391             (strncmp(ChrPtr(ReqLine), "/tiny_mce/", 10) != 0) &&
 392             (strncmp(ChrPtr(ReqLine), "/wholist_section", 16) != 0) &&
 393             (strstr(ChrPtr(ReqLine), "wholist_section") == NULL)) {
 394 #endif
 395                 lprintf(5, "HTTP: %s %s\n", ReqStrs[eReqType], ChrPtr(ReqLine));
 396 #ifdef TECH_PREVIEW
 397         }
 398 #endif
 399
 400
 401         /**
 402          * While we're at it, gracefully handle requests for the
 403          * robots.txt and favicon.ico files.
 404          */
 405         if ((StrLength(ReqLine) >= 11) &&
 406             !strncasecmp(ChrPtr(ReqLine), "/robots.txt", 11)) {
 407                 StrBufPlain(ReqLine,
 408                             HKEY("/static/robots.txt"
 409                                  "?force_close_session=yes HTTP/1.1"));
 410                 eReqType = eGET;
 411         }
 412         else if ((StrLength(ReqLine) >= 11) &&
 413                  !strncasecmp(ChrPtr(ReqLine), "/favicon.ico", 12)) {
 414                 StrBufPlain(ReqLine, HKEY("/static/favicon.ico"));
 415                 eReqType = eGET;
 416         }
 417
 418         /**
 419          * These are the URL's which may be executed without a
 420          * session cookie already set.  If it's not one of these,
 421          * force the session to close because cookies are
 422          * probably disabled on the client browser.
 423          */
 424         else if ( (StrLength(ReqLine) > 1 )
 425                 && (strncasecmp(ChrPtr(ReqLine), "/listsub", 8))
 426                 && (strncasecmp(ChrPtr(ReqLine), "/freebusy", 9))
 427                 && (strncasecmp(ChrPtr(ReqLine), "/do_logout", 10))
 428                 && (strncasecmp(ChrPtr(ReqLine), "/groupdav", 9))
 429                 && (strncasecmp(ChrPtr(ReqLine), "/static", 7))
 430                 && (strncasecmp(ChrPtr(ReqLine), "/rss", 4))
 431                 && (strncasecmp(ChrPtr(ReqLine), "/404", 4))
 432                 && (got_cookie == 0)) {
 433                 StrBufPlain(ReqLine,
 434                             HKEY("/static/nocookies.html"
 435                                  "?force_close_session=yes"));
 436         }
 437
 438         /**
 439          * See if there's an existing session open with the desired ID or user/pass
 440          */
 441         TheSession = NULL;
 442
 443         if (TheSession == NULL) {
 444                 pthread_mutex_lock(&SessionListMutex);
 445                 for (sptr = SessionList;
 446                      ((sptr != NULL) && (TheSession == NULL));
 447                       sptr = sptr->next) {
 448
 449                         /** If HTTP-AUTH, look for a session with matching credentials */
 450                         if ( (!IsEmptyStr(httpauth_user))
 451                              &&(!strcasecmp(ChrPtr(sptr->httpauth_user), httpauth_user))
 452                              &&(!strcasecmp(ChrPtr(sptr->httpauth_pass), httpauth_pass)) ) {
 453                                 TheSession = sptr;
 454                         }
 455
 456                         /** If cookie-session, look for a session with matching session ID */
 457                         if ( (desired_session != 0) && (sptr->wc_session == desired_session)) {
 458                                 TheSession = sptr;
 459                         }
 460
 461                 }
 462                 pthread_mutex_unlock(&SessionListMutex);
 463         }
 464
 465         /**
 466          * Create a new session if we have to
 467          */
 468         if (TheSession == NULL) {
 469                 lprintf(3, "Creating a new session\n");
 470                 TheSession = (wcsession *)
 471                         malloc(sizeof(wcsession));
 472                 memset(TheSession, 0, sizeof(wcsession));
 473                 TheSession->headers = HTTPHeaders;
 474                 TheSession->serv_sock = (-1);
 475                 TheSession->chat_sock = (-1);
 476
 477                 /* If we're recreating a session that expired, it's best to give it the same
 478                  * session number that it had before.  The client browser ought to pick up
 479                  * the new session number and start using it, but in some rare situations it
 480                  * doesn't, and that's a Bad Thing because it causes lots of spurious sessions
 481                  * to get created.
 482                  */
 483                 if (desired_session == 0) {
 484                         TheSession->wc_session = GenerateSessionID();
 485                 }
 486                 else {
 487                         TheSession->wc_session = desired_session;
 488                 }
 489
 490                 TheSession->httpauth_user = NewStrBufPlain(httpauth_user, -1);
 491                 TheSession->httpauth_pass = NewStrBufPlain(httpauth_user, -1);
 492
 493                 pthread_setspecific(MyConKey, (void *)TheSession);
 494                 session_new_modules(TheSession);
 495
 496                 pthread_mutex_init(&TheSession->SessionMutex, NULL);
 497                 pthread_mutex_lock(&SessionListMutex);
 498                 TheSession->nonce = rand();
 499                 TheSession->next = SessionList;
 500                 TheSession->is_mobile = -1;
 501                 SessionList = TheSession;
 502                 pthread_mutex_unlock(&SessionListMutex);
 503         }
 504
 505         /*
 506          * A future improvement might be to check the session integrity
 507          * at this point before continuing.
 508          */
 509
 510         /*
 511          * Bind to the session and perform the transaction
 512          */
 513         pthread_mutex_lock(&TheSession->SessionMutex);          /* bind */
 514         pthread_setspecific(MyConKey, (void *)TheSession);
 515
 516         TheSession->eReqType = eReqType;
 517         TheSession->headers = HTTPHeaders;
 518         TheSession->lastreq = time(NULL);                       /* log */
 519         TheSession->http_sock = *sock;
 520         TheSession->gzip_ok = gzip_ok;
 521
 522         session_attach_modules(TheSession);
 523         session_loop(ReqLine, Buf, &Pos);                               /* do transaction */
 524         session_detach_modules(TheSession);
 525
 526         TheSession->headers = NULL;
 527         pthread_mutex_unlock(&TheSession->SessionMutex);        /* unbind */
 528
 529         /* Free the request buffer */
 530         DeleteHash(&HTTPHeaders);
 531         FreeStrBuf(&ReqLine);
 532         FreeStrBuf(&Buf);
 533 }
 534
 535 void tmplput_nonce(StrBuf *Target, WCTemplputParams *TP)
 536 {
 537         wcsession *WCC = WC;
 538         StrBufAppendPrintf(Target, "%ld",
 539                            (WCC != NULL)? WCC->nonce:0);
 540 }
 541
 542 void tmplput_current_user(StrBuf *Target, WCTemplputParams *TP)
 543 {
 544         StrBufAppendTemplate(Target, TP, WC->wc_fullname, 0);
 545 }
 546
 547 void tmplput_current_room(StrBuf *Target, WCTemplputParams *TP)
 548 {
 549         StrBufAppendTemplate(Target, TP, WC->wc_roomname, 0);
 550 }
 551
 552 const char *ReqStrs[eNONE] = {
 553         "GET",
 554         "POST",
 555         "OPTIONS",
 556         "PROPFIND",
 557         "PUT",
 558         "DELETE",
 559         "HEAD",
 560         "MOVE",
 561         "COPY"
 562 };
 563
 564 void
 565 ServerStartModule_CONTEXT
 566 (void)
 567 {
 568         long *v;
 569         HttpReqTypes = NewHash(1, NULL);
 570
 571
 572         v = malloc(sizeof(long));
 573         *v = eGET;
 574         Put(HttpReqTypes, HKEY("GET"), v, NULL);
 575
 576         v = malloc(sizeof(long));
 577         *v = ePOST;
 578         Put(HttpReqTypes, HKEY("POST"), v, NULL);
 579
 580         v = malloc(sizeof(long));
 581         *v = eOPTIONS;
 582         Put(HttpReqTypes, HKEY("OPTIONS"), v, NULL);
 583
 584         v = malloc(sizeof(long));
 585         *v = ePROPFIND;
 586         Put(HttpReqTypes, HKEY("PROPFIND"), v, NULL);
 587
 588         v = malloc(sizeof(long));
 589         *v = ePUT;
 590         Put(HttpReqTypes, HKEY("PUT"), v, NULL);
 591
 592         v = malloc(sizeof(long));
 593         *v = eDELETE;
 594         Put(HttpReqTypes, HKEY("DELETE"), v, NULL);
 595
 596         v = malloc(sizeof(long));
 597         *v = eHEAD;
 598         Put(HttpReqTypes, HKEY("HEAD"), v, NULL);
 599
 600         v = malloc(sizeof(long));
 601         *v = eMOVE;
 602         Put(HttpReqTypes, HKEY("MOVE"), v, NULL);
 603
 604         v = malloc(sizeof(long));
 605         *v = eCOPY;
 606         Put(HttpReqTypes, HKEY("COPY"), v, NULL);
 607 }
 608
 609 void
 610 ServerShutdownModule_CONTEXT
 611 (void)
 612 {
 613         DeleteHash(&HttpReqTypes);
 614 }
 615
 616
 617 void
 618 InitModule_CONTEXT
 619 (void)
 620 {
 621         RegisterNamespace("CURRENT_USER", 0, 1, tmplput_current_user, CTX_NONE);
 622         RegisterNamespace("CURRENT_ROOM", 0, 1, tmplput_current_room, CTX_NONE);
 623         RegisterNamespace("NONCE", 0, 0, tmplput_nonce, 0);
 624 }