citadel/modules/xmpp/serv_xmpp.c

   1 /*
   2  * XMPP (Jabber) service for the Citadel system
   3  * Copyright (c) 2007-2021 by Art Cancro and citadel.org
   4  *
   5  * This program is open source software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 3 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write to the Free Software
  17  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  18  */
  19
  20 #include "sysdep.h"
  21 #include <stdlib.h>
  22 #include <unistd.h>
  23 #include <stdio.h>
  24 #include <fcntl.h>
  25 #include <signal.h>
  26 #include <pwd.h>
  27 #include <errno.h>
  28 #include <sys/types.h>
  29
  30 #if TIME_WITH_SYS_TIME
  31 # include <sys/time.h>
  32 # include <time.h>
  33 #else
  34 # if HAVE_SYS_TIME_H
  35 #  include <sys/time.h>
  36 # else
  37 #  include <time.h>
  38 # endif
  39 #endif
  40
  41 #include <sys/wait.h>
  42 #include <string.h>
  43 #include <limits.h>
  44 #include <ctype.h>
  45 #include <libcitadel.h>
  46 #include <expat.h>
  47 #include "citadel.h"
  48 #include "server.h"
  49 #include "citserver.h"
  50 #include "support.h"
  51 #include "config.h"
  52 #include "user_ops.h"
  53 #include "database.h"
  54 #include "msgbase.h"
  55 #include "internet_addressing.h"
  56 #include "ctdl_module.h"
  57 #include "serv_xmpp.h"
  58
  59 /* uncomment for more verbosity - it will log all received XML tags */
  60 // #define XMPP_XML_DEBUG
  61
  62 /* XML_StopParser is present in expat 2.x */
  63 #if XML_MAJOR_VERSION > 1
  64 #define HAVE_XML_STOPPARSER
  65 #endif
  66
  67 struct xmpp_event *xmpp_queue = NULL;
  68
  69 #ifdef HAVE_XML_STOPPARSER
  70 /* Stop the parser if an entity declaration is hit. */
  71 static void xmpp_entity_declaration(void *userData, const XML_Char *entityName,
  72                                 int is_parameter_entity, const XML_Char *value,
  73                                 int value_length, const XML_Char *base,
  74                                 const XML_Char *systemId, const XML_Char *publicId,
  75                                 const XML_Char *notationName
  76 ) {
  77         syslog(LOG_WARNING, "xmpp: illegal entity declaration encountered; stopping parser.");
  78         XML_StopParser(XMPP->xp, XML_FALSE);
  79 }
  80 #endif
  81
  82
  83 /*
  84  * support function for xmlesc() which helps with UTF-8 strings
  85  */
  86 static inline int Ctdl_GetUtf8SequenceLength(const char *CharS, const char *CharE)
  87 {
  88         int n = 0;
  89         unsigned char test = (1<<7);
  90
  91         if ((*CharS & 0xC0) != 0xC0) {
  92                 return 1;
  93         }
  94
  95         while ((n < 8) && ((test & ((unsigned char)*CharS)) != 0))  {
  96                 test = test >> 1;
  97                 n ++;
  98         }
  99         if ((n > 6) || ((CharE - CharS) < n)) {
 100                 n = 0;
 101         }
 102         return n;
 103 }
 104
 105
 106 /*
 107  * Given a source string and a target buffer, returns the string
 108  * properly escaped for insertion into an XML stream.  Returns a
 109  * pointer to the target buffer for convenience.
 110  */
 111 char *xmlesc(char *buf, char *str, int bufsiz)
 112 {
 113         int IsUtf8Sequence;
 114         char *ptr, *pche;
 115         unsigned char ch;
 116         int inlen;
 117         int len = 0;
 118
 119         if (!buf) return(NULL);
 120         buf[0] = 0;
 121         len = 0;
 122         if (!str) {
 123                 return(buf);
 124         }
 125         inlen = strlen(str);
 126         pche = str + inlen;
 127
 128         for (ptr=str; *ptr; ptr++) {
 129                 ch = *ptr;
 130                 if (ch == '<') {
 131                         strcpy(&buf[len], "&lt;");
 132                         len += 4;
 133                 }
 134                 else if (ch == '>') {
 135                         strcpy(&buf[len], "&gt;");
 136                         len += 4;
 137                 }
 138                 else if (ch == '&') {
 139                         strcpy(&buf[len], "&amp;");
 140                         len += 5;
 141                 }
 142                 else if ((ch >= 0x20) && (ch <= 0x7F)) {
 143                         buf[len++] = ch;
 144                         buf[len] = 0;
 145                 }
 146                 else if (ch < 0x20) {
 147                         buf[len++] = '_';       // we probably shouldn't be doing this
 148                         buf[len] = 0;
 149                 }
 150                 else {
 151                         IsUtf8Sequence =  Ctdl_GetUtf8SequenceLength(ptr, pche);
 152                         if (IsUtf8Sequence)
 153                         {
 154                                 while ((IsUtf8Sequence > 0) &&
 155                                        (ptr < pche))
 156                                 {
 157                                         buf[len] = *ptr;
 158                                         ptr ++;
 159                                         --IsUtf8Sequence;
 160                                 }
 161                         }
 162                         else
 163                         {
 164                                 char oct[10];
 165                                 sprintf(oct, "&#%o;", ch);
 166                                 strcpy(&buf[len], oct);
 167                                 len += strlen(oct);
 168                         }
 169                 }
 170                 if ((len + 6) > bufsiz) {
 171                         return(buf);
 172                 }
 173         }
 174         return(buf);
 175 }
 176
 177
 178 /*
 179  * We have just received a <stream> tag from the client, so send them ours
 180  */
 181 void xmpp_stream_start(void *data, const char *supplied_el, const char **attr)
 182 {
 183         char xmlbuf[256];
 184
 185         while (*attr) {
 186                 if (!strcasecmp(attr[0], "to")) {
 187                         safestrncpy(XMPP->server_name, attr[1], sizeof XMPP->server_name);
 188                 }
 189                 attr += 2;
 190         }
 191
 192         cprintf("<?xml version=\"1.0\" encoding=\"UTF-8\"?>");
 193         cprintf("<stream:stream ");
 194         cprintf("from=\"%s\" ", xmlesc(xmlbuf, XMPP->server_name, sizeof xmlbuf));
 195         cprintf("id=\"%08x\" ", CC->cs_pid);
 196         cprintf("version=\"1.0\" ");
 197         cprintf("xmlns:stream=\"http://etherx.jabber.org/streams\" ");
 198         cprintf("xmlns=\"jabber:client\">");
 199
 200         /* The features of this stream are... */
 201         cprintf("<stream:features>");
 202
 203         /*
 204          * TLS encryption (but only if it isn't already active)
 205          */
 206 #ifdef HAVE_OPENSSL
 207         if (!CC->redirect_ssl) {
 208                 cprintf("<starttls xmlns='urn:ietf:params:xml:ns:xmpp-tls'></starttls>");
 209         }
 210 #endif
 211
 212         if (!CC->logged_in) {
 213                 /* If we're not logged in yet, offer SASL as our feature set */
 214                 xmpp_output_auth_mechs();
 215
 216                 /* Also offer non-SASL authentication */
 217                 cprintf("<auth xmlns=\"http://jabber.org/features/iq-auth\"/>");
 218         }
 219
 220         /* Offer binding and sessions as part of our feature set */
 221         cprintf("<bind xmlns=\"urn:ietf:params:xml:ns:xmpp-bind\"/>");
 222         cprintf("<session xmlns=\"urn:ietf:params:xml:ns:xmpp-session\"/>");
 223         cprintf("</stream:features>");
 224
 225         CC->is_async = 1;               /* XMPP sessions are inherently async-capable */
 226 }
 227
 228
 229 void xmpp_xml_start(void *data, const char *supplied_el, const char **attr) {
 230         char el[256];
 231         char *sep = NULL;
 232         int i;
 233
 234         /* Create a version of the element with the namespace removed.
 235          * Now we can access "el" or "supplied_el" depending on whether we want to see the whole namespace.
 236          */
 237         safestrncpy(el, supplied_el, sizeof el);
 238         while (sep = strchr(el, ':'), sep) {
 239                 strcpy(el, ++sep);
 240         }
 241
 242 #ifdef XMPP_XML_DEBUG
 243         syslog(LOG_DEBUG, "xmpp: ELEMENT START: <%s>", el);
 244         for (i=0; attr[i] != NULL; i+=2) {
 245                 syslog(LOG_DEBUG, "xmpp: Attribute '%s' = '%s'", attr[i], attr[i+1]);
 246         }
 247 #endif
 248
 249         if (!strcasecmp(el, "stream")) {
 250                 xmpp_stream_start(data, supplied_el, attr);
 251         }
 252
 253         else if (!strcasecmp(el, "query")) {
 254                 XMPP->iq_query_xmlns[0] = 0;
 255                 safestrncpy(XMPP->iq_query_xmlns, supplied_el, sizeof XMPP->iq_query_xmlns);
 256         }
 257
 258         else if (!strcasecmp(el, "bind")) {
 259                 XMPP->bind_requested = 1;
 260         }
 261
 262         else if (!strcasecmp(el, "iq")) {
 263                 for (i=0; attr[i] != NULL; i+=2) {
 264                         if (!strcasecmp(attr[i], "type")) {
 265                                 safestrncpy(XMPP->iq_type, attr[i+1], sizeof XMPP->iq_type);
 266                         }
 267                         else if (!strcasecmp(attr[i], "id")) {
 268                                 safestrncpy(XMPP->iq_id, attr[i+1], sizeof XMPP->iq_id);
 269                         }
 270                         else if (!strcasecmp(attr[i], "from")) {
 271                                 safestrncpy(XMPP->iq_from, attr[i+1], sizeof XMPP->iq_from);
 272                         }
 273                         else if (!strcasecmp(attr[i], "to")) {
 274                                 safestrncpy(XMPP->iq_to, attr[i+1], sizeof XMPP->iq_to);
 275                         }
 276                 }
 277         }
 278
 279         else if (!strcasecmp(el, "auth")) {
 280                 XMPP->sasl_auth_mech[0] = 0;
 281                 for (i=0; attr[i] != NULL; i+=2) {
 282                         if (!strcasecmp(attr[i], "mechanism")) {
 283                                 safestrncpy(XMPP->sasl_auth_mech, attr[i+1], sizeof XMPP->sasl_auth_mech);
 284                         }
 285                 }
 286         }
 287
 288         else if (!strcasecmp(el, "message")) {
 289                 for (i=0; attr[i] != NULL; i+=2) {
 290                         if (!strcasecmp(attr[i], "to")) {
 291                                 safestrncpy(XMPP->message_to, attr[i+1], sizeof XMPP->message_to);
 292                         }
 293                 }
 294         }
 295
 296         else if (!strcasecmp(el, "html")) {
 297                 ++XMPP->html_tag_level;
 298         }
 299 }
 300
 301
 302 void xmpp_xml_end(void *data, const char *supplied_el) {
 303         char el[256];
 304         char *sep = NULL;
 305         char xmlbuf[256];
 306
 307         /* Create a version of the element with the namespace removed.
 308          * Now we can access "el" or "supplied_el" depending on whether we want to see the whole namespace.
 309          */
 310         safestrncpy(el, supplied_el, sizeof el);
 311         while (sep = strchr(el, ':'), sep) {
 312                 strcpy(el, ++sep);
 313         }
 314
 315 #ifdef XMPP_XML_DEBUG
 316         syslog(LOG_DEBUG, "xmpp: ELEMENT END  : <%s>", el);
 317         if (XMPP->chardata_len > 0) {
 318                 syslog(LOG_DEBUG, "xmpp: chardata: %s", XMPP->chardata);
 319         }
 320 #endif
 321
 322         if (!strcasecmp(el, "resource")) {
 323                 if (XMPP->chardata_len > 0) {
 324                         safestrncpy(XMPP->iq_client_resource, XMPP->chardata, sizeof XMPP->iq_client_resource);
 325                         striplt(XMPP->iq_client_resource);
 326                 }
 327         }
 328
 329         else if (!strcasecmp(el, "username")) {         /* NON SASL ONLY */
 330                 if (XMPP->chardata_len > 0) {
 331                         safestrncpy(XMPP->iq_client_username, XMPP->chardata, sizeof XMPP->iq_client_username);
 332                         striplt(XMPP->iq_client_username);
 333                 }
 334         }
 335
 336         else if (!strcasecmp(el, "password")) {         /* NON SASL ONLY */
 337                 if (XMPP->chardata_len > 0) {
 338                         safestrncpy(XMPP->iq_client_password, XMPP->chardata, sizeof XMPP->iq_client_password);
 339                         striplt(XMPP->iq_client_password);
 340                 }
 341         }
 342
 343         else if (!strcasecmp(el, "iq")) {
 344
 345                 /*
 346                  * iq type="get" (handle queries)
 347                  */
 348                 if (!strcasecmp(XMPP->iq_type, "get")) {
 349
 350                         /*
 351                          * Query on a namespace
 352                          */
 353                         if (!IsEmptyStr(XMPP->iq_query_xmlns)) {
 354                                 xmpp_query_namespace(XMPP->iq_id, XMPP->iq_from, XMPP->iq_to, XMPP->iq_query_xmlns);
 355                         }
 356
 357                         /*
 358                          * ping ( http://xmpp.org/extensions/xep-0199.html )
 359                          */
 360                         else if (XMPP->ping_requested) {
 361                                 cprintf("<iq type=\"result\" ");
 362                                 if (!IsEmptyStr(XMPP->iq_from)) {
 363                                         cprintf("to=\"%s\" ", xmlesc(xmlbuf, XMPP->iq_from, sizeof xmlbuf));
 364                                 }
 365                                 if (!IsEmptyStr(XMPP->iq_to)) {
 366                                         cprintf("from=\"%s\" ", xmlesc(xmlbuf, XMPP->iq_to, sizeof xmlbuf));
 367                                 }
 368                                 cprintf("id=\"%s\"/>", xmlesc(xmlbuf, XMPP->iq_id, sizeof xmlbuf));
 369                         }
 370
 371                         /*
 372                          * Client is requesting its own vCard
 373                          * (If we make this more elaborate, move it to a separate function)
 374                          */
 375                         else if (XMPP->iq_vcard) {
 376                                 cprintf("<iq type=\"result\" id=\"%s\" ", xmlesc(xmlbuf, XMPP->iq_id, sizeof xmlbuf));
 377                                 cprintf("to=\"%s\">", xmlesc(xmlbuf, XMPP->iq_from, sizeof xmlbuf));
 378                                 cprintf("<vCard xmlns=\"vcard-temp\">");
 379                                 cprintf("<fn>%s</fn>", xmlesc(xmlbuf, CC->user.fullname, sizeof xmlbuf));
 380                                 cprintf("<nickname>%s</nickname>", xmlesc(xmlbuf, CC->user.fullname, sizeof xmlbuf));
 381                                 cprintf("</vCard>");
 382                                 cprintf("</iq>");
 383                         }
 384
 385                         /*
 386                          * Unknown query ... return the XML equivalent of a blank stare
 387                          */
 388                         else {
 389                                 syslog(LOG_DEBUG, "xmpp: Unknown query <%s> - returning <service-unavailable/>", el);
 390                                 cprintf("<iq type=\"error\" id=\"%s\">", xmlesc(xmlbuf, XMPP->iq_id, sizeof xmlbuf));
 391                                 cprintf("<error code=\"503\" type=\"cancel\">"
 392                                         "<service-unavailable xmlns=\"urn:ietf:params:xml:ns:xmpp-stanzas\"/>"
 393                                         "</error>"
 394                                 );
 395                                 cprintf("</iq>");
 396                         }
 397                 }
 398
 399                 /*
 400                  * Non SASL authentication
 401                  */
 402                 else if (
 403                         (!strcasecmp(XMPP->iq_type, "set"))
 404                         && (!strcasecmp(XMPP->iq_query_xmlns, "jabber:iq:auth:query"))
 405                 ) {
 406                         xmpp_non_sasl_authenticate(XMPP->iq_id, XMPP->iq_client_username, XMPP->iq_client_password);
 407                 }
 408
 409                 /*
 410                  * If this <iq> stanza was a "bind" attempt, process it ...
 411                  */
 412                 else if (
 413                         (XMPP->bind_requested)
 414                         && (!IsEmptyStr(XMPP->iq_id))
 415                         && (CC->logged_in)
 416                 ) {
 417                         /* If the client has not specified a client resource, generate one */
 418                         if (IsEmptyStr(XMPP->iq_client_resource)) {
 419                                 snprintf(XMPP->iq_client_resource, sizeof XMPP->iq_client_resource, "%d", CC->cs_pid);
 420                         }
 421
 422                         /* Generate the "full JID" of the client (user@host/resource) */
 423                         snprintf(XMPP->client_jid, sizeof XMPP->client_jid, "%s/%s", CC->cs_principal_id, XMPP->iq_client_resource);
 424
 425                         /* Tell the client what its JID is */
 426                         cprintf("<iq type=\"result\" id=\"%s\">", xmlesc(xmlbuf, XMPP->iq_id, sizeof xmlbuf));
 427                         cprintf("<bind xmlns=\"urn:ietf:params:xml:ns:xmpp-bind\">");
 428                         cprintf("<jid>%s</jid>", xmlesc(xmlbuf, XMPP->client_jid, sizeof xmlbuf));
 429                         cprintf("</bind>");
 430                         cprintf("</iq>");
 431                 }
 432
 433                 else if (XMPP->iq_session) {
 434                         cprintf("<iq type=\"result\" id=\"%s\">", xmlesc(xmlbuf, XMPP->iq_id, sizeof xmlbuf));
 435                         cprintf("</iq>");
 436                 }
 437
 438                 else {
 439                         cprintf("<iq type=\"error\" id=\"%s\">", xmlesc(xmlbuf, XMPP->iq_id, sizeof xmlbuf));
 440                         cprintf("<error>Don't know how to do '%s'!</error>", xmlesc(xmlbuf, XMPP->iq_type, sizeof xmlbuf));
 441                         cprintf("</iq>");
 442                         syslog(LOG_DEBUG, "XMPP: don't know how to do iq_type='%s' with iq_query_xmlns='%s'", XMPP->iq_type, XMPP->iq_query_xmlns);
 443                 }
 444
 445                 /* Now clear these fields out so they don't get used by a future stanza */
 446                 XMPP->iq_id[0] = 0;
 447                 XMPP->iq_from[0] = 0;
 448                 XMPP->iq_to[0] = 0;
 449                 XMPP->iq_type[0] = 0;
 450                 XMPP->iq_client_resource[0] = 0;
 451                 XMPP->iq_session = 0;
 452                 XMPP->iq_vcard = 0;
 453                 XMPP->iq_query_xmlns[0] = 0;
 454                 XMPP->bind_requested = 0;
 455                 XMPP->ping_requested = 0;
 456         }
 457
 458         else if (!strcasecmp(el, "auth")) {
 459                 /* Try to authenticate (this function is responsible for the output stanza) */
 460                 xmpp_sasl_auth(XMPP->sasl_auth_mech, (XMPP->chardata != NULL ? XMPP->chardata : "") );
 461
 462                 /* Now clear these fields out so they don't get used by a future stanza */
 463                 XMPP->sasl_auth_mech[0] = 0;
 464         }
 465
 466         else if (!strcasecmp(el, "session")) {
 467                 XMPP->iq_session = 1;
 468         }
 469
 470         else if (!strcasecmp(supplied_el, "vcard-temp:vCard")) {
 471                 XMPP->iq_vcard = 1;
 472         }
 473
 474         else if (!strcasecmp(el, "presence")) {
 475                 /* Respond to a <presence> update by firing back with presence information
 476                  * on the entire wholist.  Check this assumption, it's probably wrong.
 477                  */
 478                 xmpp_wholist_presence_dump();
 479         }
 480
 481         else if ( (!strcasecmp(el, "body")) && (XMPP->html_tag_level == 0) ) {
 482                 if (XMPP->message_body != NULL) {
 483                         free(XMPP->message_body);
 484                         XMPP->message_body = NULL;
 485                 }
 486                 if (XMPP->chardata_len > 0) {
 487                         XMPP->message_body = strdup(XMPP->chardata);
 488                 }
 489         }
 490
 491         else if (!strcasecmp(el, "message")) {
 492                 xmpp_send_message(XMPP->message_to, XMPP->message_body);
 493                 XMPP->html_tag_level = 0;
 494         }
 495
 496         else if (!strcasecmp(el, "html")) {
 497                 --XMPP->html_tag_level;
 498         }
 499
 500         else if (!strcasecmp(el, "starttls")) {
 501 #ifdef HAVE_OPENSSL
 502                 cprintf("<proceed xmlns='urn:ietf:params:xml:ns:xmpp-tls'/>");
 503                 CtdlModuleStartCryptoMsgs(NULL, NULL, NULL);
 504                 if (!CC->redirect_ssl) CC->kill_me = KILLME_NO_CRYPTO;
 505 #else
 506                 cprintf("<failure xmlns='urn:ietf:params:xml:ns:xmpp-tls'/>");
 507                 CC->kill_me = KILLME_NO_CRYPTO;
 508 #endif
 509         }
 510
 511         else if (!strcasecmp(el, "ping")) {
 512                 XMPP->ping_requested = 1;
 513         }
 514
 515         else if (!strcasecmp(el, "stream")) {
 516                 syslog(LOG_DEBUG, "xmpp: client shut down their stream");
 517                 xmpp_massacre_roster();
 518                 cprintf("</stream>\n");
 519                 CC->kill_me = KILLME_CLIENT_LOGGED_OUT;
 520         }
 521
 522         else if (!strcasecmp(el, "query")) {
 523                 /* already processed , no further action needed here */
 524         }
 525
 526         else if (!strcasecmp(el, "bind")) {
 527                 /* already processed , no further action needed here */
 528         }
 529
 530         else {
 531                 syslog(LOG_DEBUG, "xmpp: ignoring unknown tag <%s>", el);
 532         }
 533
 534         XMPP->chardata_len = 0;
 535         if (XMPP->chardata_alloc > 0) {
 536                 XMPP->chardata[0] = 0;
 537         }
 538 }
 539
 540
 541 void xmpp_xml_chardata(void *data, const XML_Char *s, int len)
 542 {
 543         citxmpp *X = XMPP;
 544
 545         if (X->chardata_alloc == 0) {
 546                 X->chardata_alloc = SIZ;
 547                 X->chardata = malloc(X->chardata_alloc);
 548         }
 549         if ((X->chardata_len + len + 1) > X->chardata_alloc) {
 550                 X->chardata_alloc = X->chardata_len + len + 1024;
 551                 X->chardata = realloc(X->chardata, X->chardata_alloc);
 552         }
 553         memcpy(&X->chardata[X->chardata_len], s, len);
 554         X->chardata_len += len;
 555         X->chardata[X->chardata_len] = 0;
 556 }
 557
 558
 559 /*
 560  * This cleanup function blows away the temporary memory and files used by the XMPP service.
 561  */
 562 void xmpp_cleanup_function(void) {
 563
 564         /* Don't do this stuff if this is not a XMPP session! */
 565         if (CC->h_command_function != xmpp_command_loop) return;
 566
 567         if (XMPP->chardata != NULL) {
 568                 free(XMPP->chardata);
 569                 XMPP->chardata = NULL;
 570                 XMPP->chardata_len = 0;
 571                 XMPP->chardata_alloc = 0;
 572                 if (XMPP->message_body != NULL) {
 573                         free(XMPP->message_body);
 574                 }
 575         }
 576         XML_ParserFree(XMPP->xp);
 577         free(XMPP);
 578 }
 579
 580
 581 /*
 582  * Here's where our XMPP session begins its happy day.
 583  */
 584 void xmpp_greeting(void) {
 585         client_set_inbound_buf(4);
 586         strcpy(CC->cs_clientname, "XMPP session");
 587         CC->session_specific_data = malloc(sizeof(citxmpp));
 588         memset(XMPP, 0, sizeof(citxmpp));
 589         XMPP->last_event_processed = queue_event_seq;
 590
 591         /* XMPP does not use a greeting, but we still have to initialize some things. */
 592
 593         XMPP->xp = XML_ParserCreateNS("UTF-8", ':');
 594         if (XMPP->xp == NULL) {
 595                 syslog(LOG_ERR, "xmpp: cannot create XML parser");
 596                 CC->kill_me = KILLME_XML_PARSER;
 597                 return;
 598         }
 599
 600         XML_SetElementHandler(XMPP->xp, xmpp_xml_start, xmpp_xml_end);
 601         XML_SetCharacterDataHandler(XMPP->xp, xmpp_xml_chardata);
 602         // XML_SetUserData(XMPP->xp, something...);
 603
 604         /* Prevent the "billion laughs" attack against expat by disabling
 605          * internal entity expansion.  With 2.x, forcibly stop the parser
 606          * if an entity is declared - this is safer and a more obvious
 607          * failure mode.  With older versions, simply prevent expansion
 608          * of such entities. */
 609 #ifdef HAVE_XML_STOPPARSER
 610         XML_SetEntityDeclHandler(XMPP->xp, xmpp_entity_declaration);
 611 #else
 612         XML_SetDefaultHandler(XMPP->xp, NULL);
 613 #endif
 614
 615         CC->can_receive_im = 1;         /* This protocol is capable of receiving instant messages */
 616 }
 617
 618
 619 /*
 620  * Main command loop for XMPP sessions.
 621  */
 622 void xmpp_command_loop(void) {
 623         int rc;
 624         StrBuf *stream_input = NewStrBuf();
 625
 626         time(&CC->lastcmd);
 627         rc = client_read_random_blob(stream_input, 30);
 628         if (rc > 0) {
 629                 XML_Parse(XMPP->xp, ChrPtr(stream_input), rc, 0);
 630         }
 631         else {
 632                 syslog(LOG_ERR, "xmpp: client disconnected: ending session.");
 633                 CC->kill_me = KILLME_CLIENT_DISCONNECTED;
 634         }
 635         FreeStrBuf(&stream_input);
 636 }
 637
 638
 639 /*
 640  * Async loop for XMPP sessions (handles the transmission of unsolicited stanzas)
 641  */
 642 void xmpp_async_loop(void) {
 643         xmpp_process_events();
 644         xmpp_output_incoming_messages();
 645 }
 646
 647
 648 /*
 649  * Login hook for XMPP sessions
 650  */
 651 void xmpp_login_hook(void) {
 652         xmpp_queue_event(XMPP_EVT_LOGIN, CC->cs_principal_id);
 653 }
 654
 655
 656 /*
 657  * Logout hook for XMPP sessions
 658  */
 659 void xmpp_logout_hook(void) {
 660         xmpp_queue_event(XMPP_EVT_LOGOUT, CC->cs_principal_id);
 661 }
 662
 663
 664 const char *CitadelServiceXMPP="XMPP";
 665 CTDL_MODULE_INIT(xmpp)
 666 {
 667         if (!threading) {
 668                 CtdlRegisterServiceHook(CtdlGetConfigInt("c_xmpp_c2s_port"),
 669                                         NULL,
 670                                         xmpp_greeting,
 671                                         xmpp_command_loop,
 672                                         xmpp_async_loop,
 673                                         CitadelServiceXMPP
 674                 );
 675                 CtdlRegisterSessionHook(xmpp_cleanup_function, EVT_STOP, PRIO_STOP + 70);
 676                 CtdlRegisterSessionHook(xmpp_login_hook, EVT_LOGIN, PRIO_LOGIN + 90);
 677                 CtdlRegisterSessionHook(xmpp_logout_hook, EVT_LOGOUT, PRIO_LOGOUT + 90);
 678                 CtdlRegisterSessionHook(xmpp_login_hook, EVT_UNSTEALTH, PRIO_UNSTEALTH + 1);
 679                 CtdlRegisterSessionHook(xmpp_logout_hook, EVT_STEALTH, PRIO_STEALTH + 1);
 680
 681         }
 682
 683         /* return our module name for the log */
 684         return "xmpp";
 685 }