/*      $OpenBSD: process.c,v 1.23 2016/03/16 15:41:10 krw Exp $        */

/*
 * Copyright (c) 1983 Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/*
 * process.c handles the requests, which can be of three types:
 *      ANNOUNCE - announce to a user that a talk is wanted
 *      LEAVE_INVITE - insert the request into the table
 *      LOOK_UP - look up to see if a request is waiting in
 *                in the table for the local user
 *      DELETE - delete invitation
 */
#include <sys/socket.h>
#include <sys/stat.h>
#include <arpa/inet.h>
#include <protocols/talkd.h>

#include <ctype.h>
#include <limits.h>
#include <netdb.h>
#include <paths.h>
#include <stdio.h>
#include <string.h>
#include <syslog.h>
#include <utmp.h>

#include "talkd.h"

#define satosin(sa)     ((struct sockaddr_in *)(sa))

void
process_request(CTL_MSG *mp, CTL_RESPONSE *rp)
{
        CTL_MSG *ptr;
        char *s;

        rp->vers = TALK_VERSION;
        rp->type = mp->type;
        rp->id_num = htonl(0);
        if (mp->vers != TALK_VERSION) {
                syslog(LOG_WARNING, "Bad protocol version %d", mp->vers);
                rp->answer = BADVERSION;
                return;
        }
        mp->id_num = ntohl(mp->id_num);
        if (ntohs(mp->addr.sa_family) != AF_INET) {
                syslog(LOG_WARNING, "Bad address, family %d",
                    ntohs(mp->addr.sa_family));
                rp->answer = BADADDR;
                return;
        }
        if (ntohs(mp->ctl_addr.sa_family) != AF_INET) {
                syslog(LOG_WARNING, "Bad control address, family %d",
                    ntohs(mp->ctl_addr.sa_family));
                rp->answer = BADCTLADDR;
                return;
        }
        for (s = mp->l_name; *s; s++)
                if (!isprint((unsigned char)*s)) {
                        syslog(LOG_NOTICE, "Illegal user name. Aborting");
                        rp->answer = FAILED;
                        return;
                }
        if (memcmp(&satosin(&rp->addr)->sin_addr,
            &satosin(&mp->ctl_addr)->sin_addr,
            sizeof(struct in_addr))) {
                char buf1[32], buf2[32];

                strlcpy(buf1, inet_ntoa(satosin(&rp->addr)->sin_addr),
                    sizeof(buf1));
                strlcpy(buf2, inet_ntoa(satosin(&mp->ctl_addr)->sin_addr),
                    sizeof(buf2));
                syslog(LOG_WARNING, "addresses are different, %s != %s",
                    buf1, buf2);
        }
        rp->addr.sa_family = 0;
        mp->pid = ntohl(mp->pid);
        if (debug)
                print_request("process_request", mp);
        switch (mp->type) {

        case ANNOUNCE:
                do_announce(mp, rp);
                break;

        case LEAVE_INVITE:
                ptr = find_request(mp);
                if (ptr != NULL) {
                        rp->id_num = htonl(ptr->id_num);
                        rp->answer = SUCCESS;
                } else
                        insert_table(mp, rp);
                break;

        case LOOK_UP:
                ptr = find_match(mp);
                if (ptr != NULL) {
                        rp->id_num = htonl(ptr->id_num);
                        rp->addr = ptr->addr;
                        rp->addr.sa_family = ptr->addr.sa_family;
                        rp->answer = SUCCESS;
                } else
                        rp->answer = NOT_HERE;
                break;

        case DELETE:
                rp->answer = delete_invite(mp->id_num);
                break;

        default:
                rp->answer = UNKNOWN_REQUEST;
                break;
        }
        if (debug)
                print_response("process_request", rp);
}

void
do_announce(CTL_MSG *mp, CTL_RESPONSE *rp)
{
        struct hostent *hp;
        CTL_MSG *ptr;
        int result;

        /* see if the user is logged */
        result = find_user(mp->r_name, mp->r_tty, sizeof(mp->r_tty));
        if (result != SUCCESS) {
                rp->answer = result;
                return;
        }
        hp = gethostbyaddr((char *)&satosin(&mp->ctl_addr)->sin_addr,
                sizeof(struct in_addr), AF_INET);
        if (hp == NULL) {
                rp->answer = MACHINE_UNKNOWN;
                return;
        }
        ptr = find_request(mp);
        if (ptr == (CTL_MSG *) 0) {
                insert_table(mp, rp);
                rp->answer = announce(mp, hp->h_name);
                return;
        }
        if (mp->id_num > ptr->id_num) {
                /*
                 * This is an explicit re-announce, so update the id_num
                 * field to avoid duplicates and re-announce the talk.
                 */
                ptr->id_num = new_id();
                rp->id_num = htonl(ptr->id_num);
                rp->answer = announce(mp, hp->h_name);
        } else {
                /* a duplicated request, so ignore it */
                rp->id_num = htonl(ptr->id_num);
                rp->answer = SUCCESS;
        }
}

/*
 * Search utmp for the local user
 */
int
find_user(char *name, char *tty, size_t ttyl)
{
        struct utmp ubuf, ubuf1;
        int status;
        FILE *fp;
        char line[UT_LINESIZE+1];
        char ftty[PATH_MAX];
        time_t  idle, now;

        time(&now);
        idle = INT_MAX;
        if ((fp = fopen(_PATH_UTMP, "r")) == NULL) {
                fprintf(stderr, "talkd: can't read %s.\n", _PATH_UTMP);
                return (FAILED);
        }
#define SCMPN(a, b)     strncmp(a, b, sizeof(a))
        status = NOT_HERE;
        (void) strlcpy(ftty, _PATH_DEV, sizeof(ftty));
        while (fread((char *) &ubuf, sizeof(ubuf), 1, fp) == 1)
                if (SCMPN(ubuf.ut_name, name) == 0) {
                        if (*tty == '\0') {
                                /* no particular tty was requested */
                                struct stat statb;

                                memcpy(line, ubuf.ut_line, UT_LINESIZE);
                                line[sizeof(line)-1] = '\0';
                                ftty[sizeof(_PATH_DEV)-1] = '\0';
                                strlcat(ftty, line, sizeof(ftty));
                                if (stat(ftty, &statb) == 0) {
                                        if (!(statb.st_mode & S_IWGRP)) {
                                                if (status == NOT_HERE)
                                                        status = PERMISSION_DENIED;
                                        } else if (now - statb.st_atime < idle) {
                                                idle = now - statb.st_atime;
                                                status = SUCCESS;
                                                ubuf1 = ubuf;
                                        }
                                }
                        } else if (SCMPN(ubuf.ut_line, tty) == 0) {
                                status = SUCCESS;
                                break;
                        }
                }
        fclose(fp);
        if (*tty == '\0' && status == SUCCESS) {
                memcpy(line, ubuf1.ut_line, UT_LINESIZE);
                line[sizeof(line)-1] = '\0';
                strlcpy(tty, line, ttyl);
        }
        return (status);
}