xmpp_presence.c

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/*
 * Handle XMPP presence exchanges
 *
 * Copyright (c) 2007-2021 by Art Cancro and citadel.org
 *
 * This program is open source software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 */
 
#include "../../sysdep.h"
#include <stdlib.h>
#include <unistd.h>
#include <stdio.h>
#include <fcntl.h>
#include <signal.h>
#include <pwd.h>
#include <errno.h>
#include <sys/types.h>
#include <assert.h>
#include <time.h>
#include <sys/wait.h>
#include <string.h>
#include <limits.h>
#include <ctype.h>
#include <expat.h>
#include <libcitadel.h>
#include "../../citadel_defs.h"
#include "../../server.h"
#include "../../citserver.h"
#include "../../support.h"
#include "../../config.h"
#include "../../internet_addressing.h"
#include "../../ctdl_module.h"
#include "serv_xmpp.h"
 
 
/* 
 * Indicate the presence of another user to the client
 * (used in several places)
 */
void xmpp_indicate_presence(char *presence_jid) {
    char xmlbuf[256];
 
    syslog(LOG_DEBUG, "xmpp: indicating presence of <%s> to <%s>", presence_jid, XMPP->client_jid);
    cprintf("<presence from=\"%s\" ", xmlesc(xmlbuf, presence_jid, sizeof xmlbuf));
    cprintf("to=\"%s\"></presence>", xmlesc(xmlbuf, XMPP->client_jid, sizeof xmlbuf));
}
 
 
/*
 * Convenience function to determine whether any given session is 'visible' to any other given session,
 * and is capable of receiving instant messages from that session.
 */
int xmpp_is_visible(struct CitContext *cptr, struct CitContext *to_whom) {
    int aide = (to_whom->user.axlevel >= AxAideU);
 
    if (    (cptr->logged_in)
        &&  (((cptr->cs_flags&CS_STEALTH)==0) || (aide))    /* aides see everyone */
        &&  (cptr->user.usernum != to_whom->user.usernum)   /* don't show myself */
        &&  (cptr->can_receive_im)              /* IM-capable session */
    ) {
        return(1);
    }
    else {
        return(0);
    }
}
 
 
/* 
 * Initial dump of the entire wholist
 */
void xmpp_wholist_presence_dump(void) {
    struct CitContext *cptr = NULL;
    int nContexts, i;
    
    cptr = CtdlGetContextArray(&nContexts);
    if (!cptr) {
        return;
    }
 
    for (i=0; i<nContexts; i++) {
        if (xmpp_is_visible(&cptr[i], CC)) {
            xmpp_indicate_presence(cptr[i].cs_principal_id);
        }
    }
    free(cptr);
}
 
 
/*
 * Function to remove a buddy subscription and delete from the roster
 * (used in several places)
 */
void xmpp_destroy_buddy(char *presence_jid, int aggressively) {
    static int unsolicited_id = 1;
    char xmlbuf1[256];
    char xmlbuf2[256];
 
    if (!presence_jid) return;
    if (!XMPP) return;
    if (!XMPP->client_jid) return;
 
    /* Transmit non-presence information */
    cprintf("<presence type=\"unavailable\" from=\"%s\" to=\"%s\"></presence>",
        xmlesc(xmlbuf1, presence_jid, sizeof xmlbuf1),
        xmlesc(xmlbuf2, XMPP->client_jid, sizeof xmlbuf2)
    );
 
    /*
     * Setting the "aggressively" flag also sends an "unsubscribed" presence update.
     * We only ask for this when flushing the client side roster, because if we do it
     * in the middle of a session when another user logs off, some clients (Jitsi) interpret
     * it as a rejection of a subscription request.
     */
    if (aggressively) {
        cprintf("<presence type=\"unsubscribed\" from=\"%s\" to=\"%s\"></presence>",
            xmlesc(xmlbuf1, presence_jid, sizeof xmlbuf1),
            xmlesc(xmlbuf2, XMPP->client_jid, sizeof xmlbuf2)
        );
    }
 
    // note: we should implement xmpp_indicate_nonpresence so we can use it elsewhere
 
    /* Do an unsolicited roster update that deletes the contact. */
    cprintf("<iq from=\"%s\" to=\"%s\" id=\"unbuddy_%x\" type=\"result\">",
        xmlesc(xmlbuf1, CC->cs_principal_id, sizeof xmlbuf1),
        xmlesc(xmlbuf2, XMPP->client_jid, sizeof xmlbuf2),
        ++unsolicited_id
    );
    cprintf("<query xmlns=\"jabber:iq:roster\">");
    cprintf("<item jid=\"%s\" subscription=\"remove\">", xmlesc(xmlbuf1, presence_jid, sizeof xmlbuf1));
    cprintf("<group>%s</group>", xmlesc(xmlbuf1, CtdlGetConfigStr("c_humannode"), sizeof xmlbuf1));
    cprintf("</item>");
    cprintf("</query>"
        "</iq>"
    );
}
 
 
/*
 * When a user logs in or out of the local Citadel system, notify all XMPP sessions about it.
 * THIS FUNCTION HAS A BUG IN IT THAT ENUMERATES THE SESSIONS WRONG.
 */
void xmpp_presence_notify(char *presence_jid, int event_type) {
    struct CitContext *cptr;
    static int unsolicited_id = 12345;
    int visible_sessions = 0;
    int nContexts, i;
    int which_cptr_is_relevant = (-1);
 
    if (IsEmptyStr(presence_jid)) return;
    if (CC->kill_me) return;
 
    cptr = CtdlGetContextArray(&nContexts);
    if (!cptr) {
        return;
    }
 
    /* Count the visible sessions for this user */
    for (i=0; i<nContexts; i++) {
        if ( (!strcasecmp(cptr[i].cs_principal_id, presence_jid))
           && (xmpp_is_visible(&cptr[i], CC))
        )  {
            ++visible_sessions;
            which_cptr_is_relevant = i;
        }
    }
 
    syslog(LOG_DEBUG, "xmpp: %d sessions for <%s> are now visible to session %d", visible_sessions, presence_jid, CC->cs_pid);
 
    if ( (event_type == XMPP_EVT_LOGIN) && (visible_sessions == 1) ) {
 
        syslog(LOG_DEBUG, "xmpp: telling session %d that <%s> logged in", CC->cs_pid, presence_jid);
 
        /* Do an unsolicited roster update that adds a new contact. */
        assert(which_cptr_is_relevant >= 0);
        cprintf("<iq id=\"unsolicited_%x\" type=\"result\">", ++unsolicited_id);
        cprintf("<query xmlns=\"jabber:iq:roster\">");
        xmpp_roster_item(&cptr[which_cptr_is_relevant]);
        cprintf("</query></iq>");
 
        /* Transmit presence information */
        xmpp_indicate_presence(presence_jid);
    }
 
    if (visible_sessions == 0) {
        syslog(LOG_DEBUG, "xmpp: telling session %d that <%s> logged out", CC->cs_pid, presence_jid);
        xmpp_destroy_buddy(presence_jid, 0);    /* non aggressive presence update */
    }
 
    free(cptr);
}
 
 
void xmpp_fetch_mortuary_backend(long msgnum, void *userdata) {
    HashList *mortuary = (HashList *) userdata;
    struct CtdlMessage *msg;
    char *ptr = NULL;
    char *lasts = NULL;
 
    msg = CtdlFetchMessage(msgnum, 1);
    if (msg == NULL) {
        return;
    }
 
    /* now add anyone we find into the hashlist */
 
    /* skip past the headers */
    ptr = strstr(msg->cm_fields[eMesageText], "\n\n");
    if (ptr != NULL) {
        ptr += 2;
    }
    else {
        ptr = strstr(msg->cm_fields[eMesageText], "\n\r\n");
        if (ptr != NULL) {
            ptr += 3;
        }
    }
 
    /* the remaining lines are addresses */
    if (ptr != NULL) {
        ptr = strtok_r(ptr, "\n", &lasts);
        while (ptr != NULL) {
            char *pch = strdup(ptr);
            Put(mortuary, pch, strlen(pch), pch, NULL);
            ptr = strtok_r(NULL, "\n", &lasts);
        }
    }
 
    CM_Free(msg);
}
 
 
/*
 * Fetch the "mortuary" - a list of dead buddies which we keep around forever
 * so we can remove them from any client's roster that still has them listed
 */
HashList *xmpp_fetch_mortuary(void) {
    HashList *mortuary = NewHash(1, NULL);
    if (!mortuary) {
        syslog(LOG_ALERT, "xmpp: NewHash() failed!");
        return(NULL);
    }
 
        if (CtdlGetRoom(&CC->room, USERCONFIGROOM) != 0) {
        /* no config room exists - no further processing is required. */
                return(mortuary);
        }
        CtdlForEachMessage(MSGS_LAST, 1, NULL, XMPPMORTUARY, NULL,
                xmpp_fetch_mortuary_backend, (void *)mortuary );
 
    return(mortuary);
}
 
 
/*
 * Fetch the "mortuary" - a list of dead buddies which we keep around forever
 * so we can remove them from any client's roster that still has them listed
 */
void xmpp_store_mortuary(HashList *mortuary) {
    HashPos *HashPos;
    long len;
    void *Value;
    const char *Key;
    StrBuf *themsg;
 
    themsg = NewStrBuf();
    StrBufPrintf(themsg,    "Content-type: " XMPPMORTUARY "\n"
                "Content-transfer-encoding: 7bit\n"
                "\n"
    );
 
    HashPos = GetNewHashPos(mortuary, 0);
    while (GetNextHashPos(mortuary, HashPos, &len, &Key, &Value) != 0) {
        StrBufAppendPrintf(themsg, "%s\n", (char *)Value);
    }
    DeleteHashPos(&HashPos);
 
    /* Delete the old mortuary */
    CtdlDeleteMessages(USERCONFIGROOM, NULL, 0, XMPPMORTUARY);
 
    /* And save the new one to disk */
    quickie_message(CC->user.fullname, NULL, NULL, USERCONFIGROOM, ChrPtr(themsg), 4, "XMPP Mortuary");
    FreeStrBuf(&themsg);
}
 
 
/*
 * Upon logout we make an attempt to delete the whole roster, in order to
 * try to keep "ghost" buddies from remaining in the client-side roster.
 *
 * Since the client is probably not still alive, also remember the current
 * roster for next time so we can delete dead buddies then.
 */
void xmpp_massacre_roster(void) {
    struct CitContext *cptr;
    int nContexts, i;
    HashList *mortuary = xmpp_fetch_mortuary();
 
    cptr = CtdlGetContextArray(&nContexts);
    if (cptr) {
        for (i=0; i<nContexts; i++) {
            if (xmpp_is_visible(&cptr[i], CC)) {
                if (mortuary) {
                    char *buddy = strdup(cptr[i].cs_principal_id);
                    Put(mortuary, buddy, strlen(buddy), buddy, NULL);
                }
            }
        }
        free (cptr);
    }
 
    if (mortuary) {
        xmpp_store_mortuary(mortuary);
        DeleteHash(&mortuary);
    }
}
 
 
/*
 * Stupidly, XMPP does not specify a way to tell the client to flush its client-side roster
 * and prepare to receive a new one.  So instead we remember every buddy we've ever told the
 * client about, and push delete operations out at the beginning of a session.
 * 
 * We omit any users who happen to be online right now, but we still keep them in the mortuary,
 * which needs to be maintained as a list of every buddy the user has ever seen.  We don't know
 * when they're connecting from the same client and when they're connecting from a different client,
 * so we have no guarantee of what is in the client side roster at connect time.
 */
void xmpp_delete_old_buddies_who_no_longer_exist_from_the_client_roster(void) {
    long len;
    void *Value;
    const char *Key;
    struct CitContext *cptr;
    int nContexts, i;
    int online_now = 0;
    HashList *mortuary = xmpp_fetch_mortuary();
    HashPos *HashPos = GetNewHashPos(mortuary, 0);
 
    /* we need to omit anyone who is currently online */
    cptr = CtdlGetContextArray(&nContexts);
 
    /* go through the list of users in the mortuary... */
    while (GetNextHashPos(mortuary, HashPos, &len, &Key, &Value) != 0)
    {
 
        online_now = 0;
        if (cptr) for (i=0; i<nContexts; i++) {
            if (xmpp_is_visible(&cptr[i], CC)) {
                if (!strcasecmp(cptr[i].cs_principal_id, (char *)Value)) {
                    online_now = 1;
                }
            }
        }
 
        if (!online_now) {
            xmpp_destroy_buddy((char *)Value, 1);   /* aggressive presence update */
        }
 
    }
    DeleteHashPos(&HashPos);
    DeleteHash(&mortuary);
    free(cptr);
}