lpr/lpd.c

/*
 * Copyright (c) 1983 Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms are permitted
 * provided that the above copyright notice and this paragraph are
 * duplicated in all such forms and that any documentation,
 * advertising materials, and other materials related to such
 * distribution and use acknowledge that the software was developed
 * by the University of California, Berkeley.  The name of the
 * University may not be used to endorse or promote products derived
 * from this software without specific prior written permission.
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 */

#ifndef lint
char copyright[] =
"@(#) Copyright (c) 1983 Regents of the University of California.\n\
 All rights reserved.\n";
#endif /* not lint */

#ifndef lint
static char sccsid[] = "@(#)lpd.c       5.6 (Berkeley) 6/30/88";
#endif /* not lint */

/*
 * lpd -- line printer daemon.
 *
 * Listen for a connection and perform the requested operation.
 * Operations are:
 *      \1printer\n
 *              check the queue for jobs and print any found.
 *      \2printer\n
 *              receive a job from another machine and queue it.
 *      \3printer [users ...] [jobs ...]\n
 *              return the current state of the queue (short form).
 *      \4printer [users ...] [jobs ...]\n
 *              return the current state of the queue (long form).
 *      \5printer person [users ...] [jobs ...]\n
 *              remove jobs from the queue.
 *
 * Strategy to maintain protected spooling area:
 *      1. Spooling area is writable only by daemon and spooling group
 *      2. lpr runs setuid root and setgrp spooling group; it uses
 *         root to access any file it wants (verifying things before
 *         with an access call) and group id to know how it should
 *         set up ownership of files in the spooling area.
 *      3. Files in spooling area are owned by root, group spooling
 *         group, with mode 660.
 *      4. lpd, lpq and lprm run setuid daemon and setgrp spooling group to
 *         access files and printer.  Users can't get to anything
 *         w/o help of lpq and lprm programs.
 */

#include "lp.h"

int     lflag;                          /* log requests flag */

int     reapchild();
int     mcleanup();

main(argc, argv)
        int argc;
        char **argv;
{
        int f, funix, finet, options, defreadfds, fromlen;
        struct sockaddr_un sun, fromunix;
        struct sockaddr_in sin, frominet;
        int omask, lfd;

        gethostname(host, sizeof(host));
        name = argv[0];

        while (--argc > 0) {
                argv++;
                if (argv[0][0] == '-')
                        switch (argv[0][1]) {
                        case 'd':
                                options |= SO_DEBUG;
                                break;
                        case 'l':
                                lflag++;
                                break;
                        }
        }

#ifndef DEBUG
        /*
         * Set up standard environment by detaching from the parent.
         */
        if (fork())
                exit(0);
        for (f = 0; f < 5; f++)
                (void) close(f);
        (void) open("/dev/null", O_RDONLY);
        (void) open("/dev/null", O_WRONLY);
        (void) dup(1);
        f = open("/dev/tty", O_RDWR);
        if (f > 0) {
                ioctl(f, TIOCNOTTY, 0);
                (void) close(f);
        }
#endif

        openlog("lpd", LOG_PID, LOG_LPR);
        (void) umask(0);
        lfd = open(MASTERLOCK, O_WRONLY|O_CREAT, 0644);
        if (lfd < 0) {
                syslog(LOG_ERR, "%s: %m", MASTERLOCK);
                exit(1);
        }
        if (flock(lfd, LOCK_EX|LOCK_NB) < 0) {
                if (errno == EWOULDBLOCK)       /* active deamon present */
                        exit(0);
                syslog(LOG_ERR, "%s: %m", MASTERLOCK);
                exit(1);
        }
        ftruncate(lfd, 0);
        /*
         * write process id for others to know
         */
        sprintf(line, "%u\n", getpid());
        f = strlen(line);
        if (write(lfd, line, f) != f) {
                syslog(LOG_ERR, "%s: %m", MASTERLOCK);
                exit(1);
        }
        signal(SIGCHLD, reapchild);
        /*
         * Restart all the printers.
         */
        startup();
        (void) unlink(SOCKETNAME);
        funix = socket(AF_UNIX, SOCK_STREAM, 0);
        if (funix < 0) {
                syslog(LOG_ERR, "socket: %m");
                exit(1);
        }
#define mask(s) (1 << ((s) - 1))
        omask = sigblock(mask(SIGHUP)|mask(SIGINT)|mask(SIGQUIT)|mask(SIGTERM));
        signal(SIGHUP, mcleanup);
        signal(SIGINT, mcleanup);
        signal(SIGQUIT, mcleanup);
        signal(SIGTERM, mcleanup);
        sun.sun_family = AF_UNIX;
        strcpy(sun.sun_path, SOCKETNAME);
        if (bind(funix, &sun, strlen(sun.sun_path) + 2) < 0) {
                syslog(LOG_ERR, "ubind: %m");
                exit(1);
        }
        sigsetmask(omask);
        defreadfds = 1 << funix;
        listen(funix, 5);
        finet = socket(AF_INET, SOCK_STREAM, 0);
        if (finet >= 0) {
                struct servent *sp;

                if (options & SO_DEBUG)
                        if (setsockopt(finet, SOL_SOCKET, SO_DEBUG, 0, 0) < 0) {
                                syslog(LOG_ERR, "setsockopt (SO_DEBUG): %m");
                                mcleanup();
                        }
                sp = getservbyname("printer", "tcp");
                if (sp == NULL) {
                        syslog(LOG_ERR, "printer/tcp: unknown service");
                        mcleanup();
                }
                sin.sin_family = AF_INET;
                sin.sin_port = sp->s_port;
                if (bind(finet, &sin, sizeof(sin), 0) < 0) {
                        syslog(LOG_ERR, "bind: %m");
                        mcleanup();
                }
                defreadfds |= 1 << finet;
                listen(finet, 5);
        }
        /*
         * Main loop: accept, do a request, continue.
         */
        for (;;) {
                int domain, nfds, s, readfds = defreadfds;

                nfds = select(20, &readfds, 0, 0, 0);
                if (nfds <= 0) {
                        if (nfds < 0 && errno != EINTR)
                                syslog(LOG_WARNING, "select: %m");
                        continue;
                }
                if (readfds & (1 << funix)) {
                        domain = AF_UNIX, fromlen = sizeof(fromunix);
                        s = accept(funix, &fromunix, &fromlen);
                } else if (readfds & (1 << finet)) {
                        domain = AF_INET, fromlen = sizeof(frominet);
                        s = accept(finet, &frominet, &fromlen);
                }
                if (s < 0) {
                        if (errno != EINTR)
                                syslog(LOG_WARNING, "accept: %m");
                        continue;
                }
                if (fork() == 0) {
                        signal(SIGCHLD, SIG_IGN);
                        signal(SIGHUP, SIG_IGN);
                        signal(SIGINT, SIG_IGN);
                        signal(SIGQUIT, SIG_IGN);
                        signal(SIGTERM, SIG_IGN);
                        (void) close(funix);
                        (void) close(finet);
                        dup2(s, 1);
                        (void) close(s);
                        if (domain == AF_INET)
                                chkhost(&frominet);
                        doit();
                        exit(0);
                }
                (void) close(s);
        }
}

reapchild()
{
        union wait status;

        while (wait3(&status, WNOHANG, 0) > 0)
                ;
}

mcleanup()
{
        if (lflag)
                syslog(LOG_INFO, "exiting");
        unlink(SOCKETNAME);
        exit(0);
}

/*
 * Stuff for handling job specifications
 */
char    *user[MAXUSERS];        /* users to process */
int     users;                  /* # of users in user array */
int     requ[MAXREQUESTS];      /* job number of spool entries */
int     requests;               /* # of spool requests */
char    *person;                /* name of person doing lprm */

char    fromb[32];      /* buffer for client's machine name */
char    cbuf[BUFSIZ];   /* command line buffer */
char    *cmdnames[] = {
        "null",
        "printjob",
        "recvjob",
        "displayq short",
        "displayq long",
        "rmjob"
};

doit()
{
        register char *cp;
        register int n;

        for (;;) {
                cp = cbuf;
                do {
                        if (cp >= &cbuf[sizeof(cbuf) - 1])
                                fatal("Command line too long");
                        if ((n = read(1, cp, 1)) != 1) {
                                if (n < 0)
                                        fatal("Lost connection");
                                return;
                        }
                } while (*cp++ != '\n');
                *--cp = '\0';
                cp = cbuf;
                if (lflag) {
                        if (*cp >= '\1' && *cp <= '\5')
                                syslog(LOG_INFO, "%s requests %s %s",
                                        from, cmdnames[*cp], cp+1);
                        else
                                syslog(LOG_INFO, "bad request (%d) from %s",
                                        *cp, from);
                }
                switch (*cp++) {
                case '\1':      /* check the queue and print any jobs there */
                        printer = cp;
                        printjob();
                        break;
                case '\2':      /* receive files to be queued */
                        printer = cp;
                        recvjob();
                        break;
                case '\3':      /* display the queue (short form) */
                case '\4':      /* display the queue (long form) */
                        printer = cp;
                        while (*cp) {
                                if (*cp != ' ') {
                                        cp++;
                                        continue;
                                }
                                *cp++ = '\0';
                                while (isspace(*cp))
                                        cp++;
                                if (*cp == '\0')
                                        break;
                                if (isdigit(*cp)) {
                                        if (requests >= MAXREQUESTS)
                                                fatal("Too many requests");
                                        requ[requests++] = atoi(cp);
                                } else {
                                        if (users >= MAXUSERS)
                                                fatal("Too many users");
                                        user[users++] = cp;
                                }
                        }
                        displayq(cbuf[0] - '\3');
                        exit(0);
                case '\5':      /* remove a job from the queue */
                        printer = cp;
                        while (*cp && *cp != ' ')
                                cp++;
                        if (!*cp)
                                break;
                        *cp++ = '\0';
                        person = cp;
                        while (*cp) {
                                if (*cp != ' ') {
                                        cp++;
                                        continue;
                                }
                                *cp++ = '\0';
                                while (isspace(*cp))
                                        cp++;
                                if (*cp == '\0')
                                        break;
                                if (isdigit(*cp)) {
                                        if (requests >= MAXREQUESTS)
                                                fatal("Too many requests");
                                        requ[requests++] = atoi(cp);
                                } else {
                                        if (users >= MAXUSERS)
                                                fatal("Too many users");
                                        user[users++] = cp;
                                }
                        }
                        rmjob();
                        break;
                }
                fatal("Illegal service request");
        }
}

/*
 * Make a pass through the printcap database and start printing any
 * files left from the last time the machine went down.
 */
startup()
{
        char buf[BUFSIZ];
        register char *cp;
        int pid;

        printer = buf;

        /*
         * Restart the daemons.
         */
        while (getprent(buf) > 0) {
                for (cp = buf; *cp; cp++)
                        if (*cp == '|' || *cp == ':') {
                                *cp = '\0';
                                break;
                        }
                if ((pid = fork()) < 0) {
                        syslog(LOG_WARNING, "startup: cannot fork");
                        mcleanup();
                }
                if (!pid) {
                        endprent();
                        printjob();
                }
        }
}

#define DUMMY ":nobody::"

/*
 * Check to see if the from host has access to the line printer.
 */
chkhost(f)
        struct sockaddr_in *f;
{
        register struct hostent *hp;
        register FILE *hostf;
        register char *cp, *sp;
        char ahost[50];
        int first = 1;
        extern char *inet_ntoa();
        int baselen = -1;

        f->sin_port = ntohs(f->sin_port);
        if (f->sin_family != AF_INET || f->sin_port >= IPPORT_RESERVED)
                fatal("Malformed from address");
        hp = gethostbyaddr(&f->sin_addr, sizeof(struct in_addr), f->sin_family);
        if (hp == 0)
                fatal("Host name for your address (%s) unknown",
                        inet_ntoa(f->sin_addr));

        strcpy(fromb, hp->h_name);
        from = fromb;
        if (!strcmp(from, host))
                return;

        sp = fromb;
        cp = ahost;
        while (*sp) {
                if (*sp == '.') {
                        if (baselen == -1)
                                baselen = sp - fromb;
                        *cp++ = *sp++;
                } else {
                        *cp++ = isupper(*sp) ? tolower(*sp++) : *sp++;
                }
        }
        *cp = '\0';
        hostf = fopen("/etc/hosts.equiv", "r");
again:
        if (hostf) {
                if (!_validuser(hostf, ahost, DUMMY, DUMMY, baselen)) {
                        (void) fclose(hostf);
                        return;
                }
                (void) fclose(hostf);
        }
        if (first == 1) {
                first = 0;
                hostf = fopen("/etc/hosts.lpd", "r");
                goto again;
        }
        fatal("Your host does not have line printer access");
}