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