citadel/modules/xmpp/serv_xmpp.c

   1 /*
   2  * XMPP (Jabber) service for the Citadel system
   3  * Copyright (c) 2007-2019 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 "md5.h"
  57 #include "ctdl_module.h"
  58 #include "serv_xmpp.h"
  59
  60 /* uncomment for more verbosity - it will log all received XML tags */
  61 // #define XMPP_XML_DEBUG
  62
  63 /* XML_StopParser is present in expat 2.x */
  64 #if XML_MAJOR_VERSION > 1
  65 #define HAVE_XML_STOPPARSER
  66 #endif
  67
  68 struct xmpp_event *xmpp_queue = NULL;
  69
  70 #ifdef HAVE_XML_STOPPARSER
  71 /* Stop the parser if an entity declaration is hit. */
  72 static void xmpp_entity_declaration(void *userData, const XML_Char *entityName,
  73                                 int is_parameter_entity, const XML_Char *value,
  74                                 int value_length, const XML_Char *base,
  75                                 const XML_Char *systemId, const XML_Char *publicId,
  76                                 const XML_Char *notationName
  77 ) {
  78         syslog(LOG_WARNING, "xmpp: illegal entity declaration encountered; stopping parser.");
  79         XML_StopParser(XMPP->xp, XML_FALSE);
  80 }
  81 #endif
  82
  83
  84 /*
  85  * support function for xmlesc() which helps with UTF-8 strings
  86  */
  87 static inline int Ctdl_GetUtf8SequenceLength(const char *CharS, const char *CharE)
  88 {
  89         int n = 0;
  90         unsigned char test = (1<<7);
  91
  92         if ((*CharS & 0xC0) != 0xC0) {
  93                 return 1;
  94         }
  95
  96         while ((n < 8) && ((test & ((unsigned char)*CharS)) != 0))  {
  97                 test = test >> 1;
  98                 n ++;
  99         }
 100         if ((n > 6) || ((CharE - CharS) < n)) {
 101                 n = 0;
 102         }
 103         return n;
 104 }
 105
 106
 107 /*
 108  * Given a source string and a target buffer, returns the string
 109  * properly escaped for insertion into an XML stream.  Returns a
 110  * pointer to the target buffer for convenience.
 111  */
 112 char *xmlesc(char *buf, char *str, int bufsiz)
 113 {
 114         int IsUtf8Sequence;
 115         char *ptr, *pche;
 116         unsigned char ch;
 117         int inlen;
 118         int len = 0;
 119
 120         if (!buf) return(NULL);
 121         buf[0] = 0;
 122         len = 0;
 123         if (!str) {
 124                 return(buf);
 125         }
 126         inlen = strlen(str);
 127         pche = str + inlen;
 128
 129         for (ptr=str; *ptr; ptr++) {
 130                 ch = *ptr;
 131                 if (ch == '<') {
 132                         strcpy(&buf[len], "&lt;");
 133                         len += 4;
 134                 }
 135                 else if (ch == '>') {
 136                         strcpy(&buf[len], "&gt;");
 137                         len += 4;
 138                 }
 139                 else if (ch == '&') {
 140                         strcpy(&buf[len], "&amp;");
 141                         len += 5;
 142                 }
 143                 else if ((ch >= 0x20) && (ch <= 0x7F)) {
 144                         buf[len++] = ch;
 145                         buf[len] = 0;
 146                 }
 147                 else if (ch < 0x20) {
 148                         buf[len++] = '_';       // we probably shouldn't be doing this
 149                         buf[len] = 0;
 150                 }
 151                 else {
 152                         IsUtf8Sequence =  Ctdl_GetUtf8SequenceLength(ptr, pche);
 153                         if (IsUtf8Sequence)
 154                         {
 155                                 while ((IsUtf8Sequence > 0) &&
 156                                        (ptr < pche))
 157                                 {
 158                                         buf[len] = *ptr;
 159                                         ptr ++;
 160                                         --IsUtf8Sequence;
 161                                 }
 162                         }
 163                         else
 164                         {
 165                                 char oct[10];
 166                                 sprintf(oct, "&#%o;", ch);
 167                                 strcpy(&buf[len], oct);
 168                                 len += strlen(oct);
 169                         }
 170                 }
 171                 if ((len + 6) > bufsiz) {
 172                         return(buf);
 173                 }
 174         }
 175         return(buf);
 176 }
 177
 178
 179 /*
 180  * We have just received a <stream> tag from the client, so send them ours
 181  */
 182 void xmpp_stream_start(void *data, const char *supplied_el, const char **attr)
 183 {
 184         char xmlbuf[256];
 185
 186         while (*attr) {
 187                 if (!strcasecmp(attr[0], "to")) {
 188                         safestrncpy(XMPP->server_name, attr[1], sizeof XMPP->server_name);
 189                 }
 190                 attr += 2;
 191         }
 192
 193         cprintf("<?xml version=\"1.0\" encoding=\"UTF-8\"?>");
 194         cprintf("<stream:stream ");
 195         cprintf("from=\"%s\" ", xmlesc(xmlbuf, XMPP->server_name, sizeof xmlbuf));
 196         cprintf("id=\"%08x\" ", CC->cs_pid);
 197         cprintf("version=\"1.0\" ");
 198         cprintf("xmlns:stream=\"http://etherx.jabber.org/streams\" ");
 199         cprintf("xmlns=\"jabber:client\">");
 200
 201         /* The features of this stream are... */
 202         cprintf("<stream:features>");
 203
 204         /*
 205          * TLS encryption (but only if it isn't already active)
 206          */
 207 #ifdef HAVE_OPENSSL
 208         if (!CC->redirect_ssl) {
 209                 cprintf("<starttls xmlns='urn:ietf:params:xml:ns:xmpp-tls'></starttls>");
 210         }
 211 #endif
 212
 213         if (!CC->logged_in) {
 214                 /* If we're not logged in yet, offer SASL as our feature set */
 215                 xmpp_output_auth_mechs();
 216
 217                 /* Also offer non-SASL authentication */
 218                 cprintf("<auth xmlns=\"http://jabber.org/features/iq-auth\"/>");
 219         }
 220
 221         /* Offer binding and sessions as part of our feature set */
 222         cprintf("<bind xmlns=\"urn:ietf:params:xml:ns:xmpp-bind\"/>");
 223         cprintf("<session xmlns=\"urn:ietf:params:xml:ns:xmpp-session\"/>");
 224         cprintf("</stream:features>");
 225
 226         CC->is_async = 1;               /* XMPP sessions are inherently async-capable */
 227 }
 228
 229
 230 void xmpp_xml_start(void *data, const char *supplied_el, const char **attr) {
 231         char el[256];
 232         char *sep = NULL;
 233         int i;
 234
 235         /* Create a version of the element with the namespace removed.
 236          * Now we can access "el" or "supplied_el" depending on whether we want to see the whole namespace.
 237          */
 238         safestrncpy(el, supplied_el, sizeof el);
 239         while (sep = strchr(el, ':'), sep) {
 240                 strcpy(el, ++sep);
 241         }
 242
 243 #ifdef XMPP_XML_DEBUG
 244         syslog(LOG_DEBUG, "xmpp: ELEMENT START: <%s>", el);
 245         for (i=0; attr[i] != NULL; i+=2) {
 246                 syslog(LOG_DEBUG, "xmpp: Attribute '%s' = '%s'", attr[i], attr[i+1]);
 247         }
 248 #endif
 249
 250         if (!strcasecmp(el, "stream")) {
 251                 xmpp_stream_start(data, supplied_el, attr);
 252         }
 253
 254         else if (!strcasecmp(el, "query")) {
 255                 XMPP->iq_query_xmlns[0] = 0;
 256                 safestrncpy(XMPP->iq_query_xmlns, supplied_el, sizeof XMPP->iq_query_xmlns);
 257         }
 258
 259         else if (!strcasecmp(el, "bind")) {
 260                 XMPP->bind_requested = 1;
 261         }
 262
 263         else if (!strcasecmp(el, "iq")) {
 264                 for (i=0; attr[i] != NULL; i+=2) {
 265                         if (!strcasecmp(attr[i], "type")) {
 266                                 safestrncpy(XMPP->iq_type, attr[i+1], sizeof XMPP->iq_type);
 267                         }
 268                         else if (!strcasecmp(attr[i], "id")) {
 269                                 safestrncpy(XMPP->iq_id, attr[i+1], sizeof XMPP->iq_id);
 270                         }
 271                         else if (!strcasecmp(attr[i], "from")) {
 272                                 safestrncpy(XMPP->iq_from, attr[i+1], sizeof XMPP->iq_from);
 273                         }
 274                         else if (!strcasecmp(attr[i], "to")) {
 275                                 safestrncpy(XMPP->iq_to, attr[i+1], sizeof XMPP->iq_to);
 276                         }
 277                 }
 278         }
 279
 280         else if (!strcasecmp(el, "auth")) {
 281                 XMPP->sasl_auth_mech[0] = 0;
 282                 for (i=0; attr[i] != NULL; i+=2) {
 283                         if (!strcasecmp(attr[i], "mechanism")) {
 284                                 safestrncpy(XMPP->sasl_auth_mech, attr[i+1], sizeof XMPP->sasl_auth_mech);
 285                         }
 286                 }
 287         }
 288
 289         else if (!strcasecmp(el, "message")) {
 290                 for (i=0; attr[i] != NULL; i+=2) {
 291                         if (!strcasecmp(attr[i], "to")) {
 292                                 safestrncpy(XMPP->message_to, attr[i+1], sizeof XMPP->message_to);
 293                         }
 294                 }
 295         }
 296
 297         else if (!strcasecmp(el, "html")) {
 298                 ++XMPP->html_tag_level;
 299         }
 300 }
 301
 302
 303 void xmpp_xml_end(void *data, const char *supplied_el) {
 304         char el[256];
 305         char *sep = NULL;
 306         char xmlbuf[256];
 307
 308         /* Create a version of the element with the namespace removed.
 309          * Now we can access "el" or "supplied_el" depending on whether we want to see the whole namespace.
 310          */
 311         safestrncpy(el, supplied_el, sizeof el);
 312         while (sep = strchr(el, ':'), sep) {
 313                 strcpy(el, ++sep);
 314         }
 315
 316 #ifdef XMPP_XML_DEBUG
 317         syslog(LOG_DEBUG, "xmpp: ELEMENT END  : <%s>", el);
 318         if (XMPP->chardata_len > 0) {
 319                 syslog(LOG_DEBUG, "xmpp: chardata: %s", XMPP->chardata);
 320         }
 321 #endif
 322
 323         if (!strcasecmp(el, "resource")) {
 324                 if (XMPP->chardata_len > 0) {
 325                         safestrncpy(XMPP->iq_client_resource, XMPP->chardata, sizeof XMPP->iq_client_resource);
 326                         striplt(XMPP->iq_client_resource);
 327                 }
 328         }
 329
 330         else if (!strcasecmp(el, "username")) {         /* NON SASL ONLY */
 331                 if (XMPP->chardata_len > 0) {
 332                         safestrncpy(XMPP->iq_client_username, XMPP->chardata, sizeof XMPP->iq_client_username);
 333                         striplt(XMPP->iq_client_username);
 334                 }
 335         }
 336
 337         else if (!strcasecmp(el, "password")) {         /* NON SASL ONLY */
 338                 if (XMPP->chardata_len > 0) {
 339                         safestrncpy(XMPP->iq_client_password, XMPP->chardata, sizeof XMPP->iq_client_password);
 340                         striplt(XMPP->iq_client_password);
 341                 }
 342         }
 343
 344         else if (!strcasecmp(el, "iq")) {
 345
 346                 /*
 347                  * iq type="get" (handle queries)
 348                  */
 349                 if (!strcasecmp(XMPP->iq_type, "get")) {
 350
 351                         /*
 352                          * Query on a namespace
 353                          */
 354                         if (!IsEmptyStr(XMPP->iq_query_xmlns)) {
 355                                 xmpp_query_namespace(XMPP->iq_id, XMPP->iq_from, XMPP->iq_to, XMPP->iq_query_xmlns);
 356                         }
 357
 358                         /*
 359                          * ping ( http://xmpp.org/extensions/xep-0199.html )
 360                          */
 361                         else if (XMPP->ping_requested) {
 362                                 cprintf("<iq type=\"result\" ");
 363                                 if (!IsEmptyStr(XMPP->iq_from)) {
 364                                         cprintf("to=\"%s\" ", xmlesc(xmlbuf, XMPP->iq_from, sizeof xmlbuf));
 365                                 }
 366                                 if (!IsEmptyStr(XMPP->iq_to)) {
 367                                         cprintf("from=\"%s\" ", xmlesc(xmlbuf, XMPP->iq_to, sizeof xmlbuf));
 368                                 }
 369                                 cprintf("id=\"%s\"/>", xmlesc(xmlbuf, XMPP->iq_id, sizeof xmlbuf));
 370                         }
 371
 372                         /*
 373                          * Client is requesting its own vCard
 374                          * (If we make this more elaborate, move it to a separate function)
 375                          */
 376                         else if (XMPP->iq_vcard) {
 377                                 cprintf("<iq type=\"result\" id=\"%s\" ", xmlesc(xmlbuf, XMPP->iq_id, sizeof xmlbuf));
 378                                 cprintf("to=\"%s\">", xmlesc(xmlbuf, XMPP->iq_from, sizeof xmlbuf));
 379                                 cprintf("<vCard xmlns=\"vcard-temp\">");
 380                                 cprintf("<fn>%s</fn>", xmlesc(xmlbuf, CC->user.fullname, sizeof xmlbuf));
 381                                 cprintf("<nickname>%s</nickname>", xmlesc(xmlbuf, CC->user.fullname, sizeof xmlbuf));
 382                                 cprintf("</vCard>");
 383                                 cprintf("</iq>");
 384                         }
 385
 386                         /*
 387                          * Unknown query ... return the XML equivalent of a blank stare
 388                          */
 389                         else {
 390                                 syslog(LOG_DEBUG, "xmpp: Unknown query <%s> - returning <service-unavailable/>", el);
 391                                 cprintf("<iq type=\"error\" id=\"%s\">", xmlesc(xmlbuf, XMPP->iq_id, sizeof xmlbuf));
 392                                 cprintf("<error code=\"503\" type=\"cancel\">"
 393                                         "<service-unavailable xmlns=\"urn:ietf:params:xml:ns:xmpp-stanzas\"/>"
 394                                         "</error>"
 395                                 );
 396                                 cprintf("</iq>");
 397                         }
 398                 }
 399
 400                 /*
 401                  * Non SASL authentication
 402                  */
 403                 else if (
 404                         (!strcasecmp(XMPP->iq_type, "set"))
 405                         && (!strcasecmp(XMPP->iq_query_xmlns, "jabber:iq:auth:query"))
 406                 ) {
 407                         xmpp_non_sasl_authenticate(XMPP->iq_id, XMPP->iq_client_username, XMPP->iq_client_password);
 408                 }
 409
 410                 /*
 411                  * If this <iq> stanza was a "bind" attempt, process it ...
 412                  */
 413                 else if (
 414                         (XMPP->bind_requested)
 415                         && (!IsEmptyStr(XMPP->iq_id))
 416                         && (CC->logged_in)
 417                 ) {
 418                         /* If the client has not specified a client resource, generate one */
 419                         if (IsEmptyStr(XMPP->iq_client_resource)) {
 420                                 snprintf(XMPP->iq_client_resource, sizeof XMPP->iq_client_resource, "%d", CC->cs_pid);
 421                         }
 422
 423                         /* Generate the "full JID" of the client (user@host/resource) */
 424                         snprintf(XMPP->client_jid, sizeof XMPP->client_jid, "%s/%s", CC->cs_inet_email, XMPP->iq_client_resource);
 425
 426                         /* Tell the client what its JID is */
 427                         cprintf("<iq type=\"result\" id=\"%s\">", xmlesc(xmlbuf, XMPP->iq_id, sizeof xmlbuf));
 428                         cprintf("<bind xmlns=\"urn:ietf:params:xml:ns:xmpp-bind\">");
 429                         cprintf("<jid>%s</jid>", xmlesc(xmlbuf, XMPP->client_jid, sizeof xmlbuf));
 430                         cprintf("</bind>");
 431                         cprintf("</iq>");
 432                 }
 433
 434                 else if (XMPP->iq_session) {
 435                         cprintf("<iq type=\"result\" id=\"%s\">", xmlesc(xmlbuf, XMPP->iq_id, sizeof xmlbuf));
 436                         cprintf("</iq>");
 437                 }
 438
 439                 else {
 440                         cprintf("<iq type=\"error\" id=\"%s\">", xmlesc(xmlbuf, XMPP->iq_id, sizeof xmlbuf));
 441                         cprintf("<error>Don't know how to do '%s'!</error>", xmlesc(xmlbuf, XMPP->iq_type, sizeof xmlbuf));
 442                         cprintf("</iq>");
 443                         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);
 444                 }
 445
 446                 /* Now clear these fields out so they don't get used by a future stanza */
 447                 XMPP->iq_id[0] = 0;
 448                 XMPP->iq_from[0] = 0;
 449                 XMPP->iq_to[0] = 0;
 450                 XMPP->iq_type[0] = 0;
 451                 XMPP->iq_client_resource[0] = 0;
 452                 XMPP->iq_session = 0;
 453                 XMPP->iq_vcard = 0;
 454                 XMPP->iq_query_xmlns[0] = 0;
 455                 XMPP->bind_requested = 0;
 456                 XMPP->ping_requested = 0;
 457         }
 458
 459         else if (!strcasecmp(el, "auth")) {
 460                 /* Try to authenticate (this function is responsible for the output stanza) */
 461                 xmpp_sasl_auth(XMPP->sasl_auth_mech, (XMPP->chardata != NULL ? XMPP->chardata : "") );
 462
 463                 /* Now clear these fields out so they don't get used by a future stanza */
 464                 XMPP->sasl_auth_mech[0] = 0;
 465         }
 466
 467         else if (!strcasecmp(el, "session")) {
 468                 XMPP->iq_session = 1;
 469         }
 470
 471         else if (!strcasecmp(supplied_el, "vcard-temp:vCard")) {
 472                 XMPP->iq_vcard = 1;
 473         }
 474
 475         else if (!strcasecmp(el, "presence")) {
 476                 /* Respond to a <presence> update by firing back with presence information
 477                  * on the entire wholist.  Check this assumption, it's probably wrong.
 478                  */
 479                 xmpp_wholist_presence_dump();
 480         }
 481
 482         else if ( (!strcasecmp(el, "body")) && (XMPP->html_tag_level == 0) ) {
 483                 if (XMPP->message_body != NULL) {
 484                         free(XMPP->message_body);
 485                         XMPP->message_body = NULL;
 486                 }
 487                 if (XMPP->chardata_len > 0) {
 488                         XMPP->message_body = strdup(XMPP->chardata);
 489                 }
 490         }
 491
 492         else if (!strcasecmp(el, "message")) {
 493                 xmpp_send_message(XMPP->message_to, XMPP->message_body);
 494                 XMPP->html_tag_level = 0;
 495         }
 496
 497         else if (!strcasecmp(el, "html")) {
 498                 --XMPP->html_tag_level;
 499         }
 500
 501         else if (!strcasecmp(el, "starttls")) {
 502 #ifdef HAVE_OPENSSL
 503                 cprintf("<proceed xmlns='urn:ietf:params:xml:ns:xmpp-tls'/>");
 504                 CtdlModuleStartCryptoMsgs(NULL, NULL, NULL);
 505                 if (!CC->redirect_ssl) CC->kill_me = KILLME_NO_CRYPTO;
 506 #else
 507                 cprintf("<failure xmlns='urn:ietf:params:xml:ns:xmpp-tls'/>");
 508                 CC->kill_me = KILLME_NO_CRYPTO;
 509 #endif
 510         }
 511
 512         else if (!strcasecmp(el, "ping")) {
 513                 XMPP->ping_requested = 1;
 514         }
 515
 516         else if (!strcasecmp(el, "stream")) {
 517                 syslog(LOG_DEBUG, "xmpp: client shut down their stream");
 518                 xmpp_massacre_roster();
 519                 cprintf("</stream>\n");
 520                 CC->kill_me = KILLME_CLIENT_LOGGED_OUT;
 521         }
 522
 523         else if (!strcasecmp(el, "query")) {
 524                 /* already processed , no further action needed here */
 525         }
 526
 527         else if (!strcasecmp(el, "bind")) {
 528                 /* already processed , no further action needed here */
 529         }
 530
 531         else {
 532                 syslog(LOG_DEBUG, "xmpp: ignoring unknown tag <%s>", el);
 533         }
 534
 535         XMPP->chardata_len = 0;
 536         if (XMPP->chardata_alloc > 0) {
 537                 XMPP->chardata[0] = 0;
 538         }
 539 }
 540
 541
 542 void xmpp_xml_chardata(void *data, const XML_Char *s, int len)
 543 {
 544         citxmpp *X = XMPP;
 545
 546         if (X->chardata_alloc == 0) {
 547                 X->chardata_alloc = SIZ;
 548                 X->chardata = malloc(X->chardata_alloc);
 549         }
 550         if ((X->chardata_len + len + 1) > X->chardata_alloc) {
 551                 X->chardata_alloc = X->chardata_len + len + 1024;
 552                 X->chardata = realloc(X->chardata, X->chardata_alloc);
 553         }
 554         memcpy(&X->chardata[X->chardata_len], s, len);
 555         X->chardata_len += len;
 556         X->chardata[X->chardata_len] = 0;
 557 }
 558
 559
 560 /*
 561  * This cleanup function blows away the temporary memory and files used by the XMPP service.
 562  */
 563 void xmpp_cleanup_function(void) {
 564
 565         /* Don't do this stuff if this is not a XMPP session! */
 566         if (CC->h_command_function != xmpp_command_loop) return;
 567
 568         if (XMPP->chardata != NULL) {
 569                 free(XMPP->chardata);
 570                 XMPP->chardata = NULL;
 571                 XMPP->chardata_len = 0;
 572                 XMPP->chardata_alloc = 0;
 573                 if (XMPP->message_body != NULL) {
 574                         free(XMPP->message_body);
 575                 }
 576         }
 577         XML_ParserFree(XMPP->xp);
 578         free(XMPP);
 579 }
 580
 581
 582 /*
 583  * Here's where our XMPP session begins its happy day.
 584  */
 585 void xmpp_greeting(void) {
 586         client_set_inbound_buf(4);
 587         strcpy(CC->cs_clientname, "XMPP session");
 588         CC->session_specific_data = malloc(sizeof(citxmpp));
 589         memset(XMPP, 0, sizeof(citxmpp));
 590         XMPP->last_event_processed = queue_event_seq;
 591
 592         /* XMPP does not use a greeting, but we still have to initialize some things. */
 593
 594         XMPP->xp = XML_ParserCreateNS("UTF-8", ':');
 595         if (XMPP->xp == NULL) {
 596                 syslog(LOG_ERR, "xmpp: cannot create XML parser");
 597                 CC->kill_me = KILLME_XML_PARSER;
 598                 return;
 599         }
 600
 601         XML_SetElementHandler(XMPP->xp, xmpp_xml_start, xmpp_xml_end);
 602         XML_SetCharacterDataHandler(XMPP->xp, xmpp_xml_chardata);
 603         // XML_SetUserData(XMPP->xp, something...);
 604
 605         /* Prevent the "billion laughs" attack against expat by disabling
 606          * internal entity expansion.  With 2.x, forcibly stop the parser
 607          * if an entity is declared - this is safer and a more obvious
 608          * failure mode.  With older versions, simply prevent expansion
 609          * of such entities. */
 610 #ifdef HAVE_XML_STOPPARSER
 611         XML_SetEntityDeclHandler(XMPP->xp, xmpp_entity_declaration);
 612 #else
 613         XML_SetDefaultHandler(XMPP->xp, NULL);
 614 #endif
 615
 616         CC->can_receive_im = 1;         /* This protocol is capable of receiving instant messages */
 617 }
 618
 619
 620 /*
 621  * Main command loop for XMPP sessions.
 622  */
 623 void xmpp_command_loop(void) {
 624         int rc;
 625         StrBuf *stream_input = NewStrBuf();
 626
 627         time(&CC->lastcmd);
 628         rc = client_read_random_blob(stream_input, 30);
 629         if (rc > 0) {
 630                 XML_Parse(XMPP->xp, ChrPtr(stream_input), rc, 0);
 631         }
 632         else {
 633                 syslog(LOG_ERR, "xmpp: client disconnected: ending session.");
 634                 CC->kill_me = KILLME_CLIENT_DISCONNECTED;
 635         }
 636         FreeStrBuf(&stream_input);
 637 }
 638
 639
 640 /*
 641  * Async loop for XMPP sessions (handles the transmission of unsolicited stanzas)
 642  */
 643 void xmpp_async_loop(void) {
 644         xmpp_process_events();
 645         xmpp_output_incoming_messages();
 646 }
 647
 648
 649 /*
 650  * Login hook for XMPP sessions
 651  */
 652 void xmpp_login_hook(void) {
 653         xmpp_queue_event(XMPP_EVT_LOGIN, CC->cs_inet_email);
 654 }
 655
 656
 657 /*
 658  * Logout hook for XMPP sessions
 659  */
 660 void xmpp_logout_hook(void) {
 661         xmpp_queue_event(XMPP_EVT_LOGOUT, CC->cs_inet_email);
 662 }
 663
 664
 665 const char *CitadelServiceXMPP="XMPP";
 666 extern void xmpp_cleanup_events(void);
 667 CTDL_MODULE_INIT(xmpp)
 668 {
 669         if (!threading) {
 670                 CtdlRegisterServiceHook(CtdlGetConfigInt("c_xmpp_c2s_port"),
 671                                         NULL,
 672                                         xmpp_greeting,
 673                                         xmpp_command_loop,
 674                                         xmpp_async_loop,
 675                                         CitadelServiceXMPP
 676                 );
 677                 CtdlRegisterSessionHook(xmpp_cleanup_function, EVT_STOP, PRIO_STOP + 70);
 678                 CtdlRegisterSessionHook(xmpp_login_hook, EVT_LOGIN, PRIO_LOGIN + 90);
 679                 CtdlRegisterSessionHook(xmpp_logout_hook, EVT_LOGOUT, PRIO_LOGOUT + 90);
 680                 CtdlRegisterSessionHook(xmpp_login_hook, EVT_UNSTEALTH, PRIO_UNSTEALTH + 1);
 681                 CtdlRegisterSessionHook(xmpp_logout_hook, EVT_STEALTH, PRIO_STEALTH + 1);
 682                 CtdlRegisterCleanupHook(xmpp_cleanup_events);
 683
 684         }
 685
 686         /* return our module name for the log */
 687         return "xmpp";
 688 }