/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1983, 1993, 1994
 *      The 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.
 */

#include "lp.cdefs.h"           /* A cross-platform version of <sys/cdefs.h> */
/*
 * 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 <sys/param.h>
#include <sys/file.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/un.h>
#include <sys/wait.h>

#include <netinet/in.h>
#include <arpa/inet.h>

#include <ctype.h>
#include <dirent.h>
#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <netdb.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sysexits.h>
#include <syslog.h>
#include <unistd.h>
#include "lp.h"
#include "lp.local.h"
#include "pathnames.h"
#include "extern.h"

int     lflag;                          /* log requests flag */
int     sflag;                          /* no incoming port flag */
int     Fflag;                          /* run in foreground flag */
int     from_remote;                    /* from remote socket */

int              main(int argc, char **_argv);
static void      reapchild(int _signo);
static void      mcleanup(int _signo);
static void      doit(void);
static void      startup(void);
static void      chkhost(struct sockaddr *_f, int _ch_opts);
static int       ckqueue(struct printer *_pp);
static void      fhosterr(int _ch_opts, char *_sysmsg, char *_usermsg);
static int      *socksetup(int _af, int _debuglvl);
static void      usage(void);

/* XXX from libc/net/rcmd.c */
extern int __ivaliduser_sa(FILE *, struct sockaddr *, socklen_t,
                                const char *, const char *);

uid_t   uid, euid;

#define LPD_NOPORTCHK   0001            /* skip reserved-port check */
#define LPD_LOGCONNERR  0002            /* (sys)log connection errors */
#define LPD_ADDFROMLINE 0004            /* just used for fhosterr() */

int
main(int argc, char **argv)
{
        struct timeval tv = { .tv_sec = 120 };
        int ch_options, errs, f, funix, *finet, i, lfd, socket_debug;
        fd_set defreadfds;
        struct sockaddr_un un, fromunix;
        struct sockaddr_storage frominet;
        socklen_t fromlen;
        sigset_t omask, nmask;
        struct servent *sp, serv;
        int inet_flag = 0, inet6_flag = 0;

        euid = geteuid();       /* these shouldn't be different */
        uid = getuid();

        ch_options = 0;
        socket_debug = 0;
        gethostname(local_host, sizeof(local_host));

        progname = "lpd";

        if (euid != 0)
                errx(EX_NOPERM,"must run as root");

        errs = 0;
        while ((i = getopt(argc, argv, "cdlpst:wFW46")) != -1)
                switch (i) {
                case 'c':
                        /* log all kinds of connection-errors to syslog */
                        ch_options |= LPD_LOGCONNERR;
                        break;
                case 'd':
                        socket_debug++;
                        break;
                case 'l':
                        lflag++;
                        break;
                case 'p':               /* letter initially used for -s */
                        /*
                         * This will probably be removed with 5.0-release.
                         */
                        /* FALLTHROUGH */
                case 's':               /* secure (no inet) */
                        sflag++;
                        break;
                case 't':
                        tv.tv_sec = atol(optarg);
                        break;
                case 'w':               /* netbsd uses -w for maxwait */
                        /*
                         * This will be removed after the release of 4.4, as
                         * it conflicts with -w in netbsd's lpd.  For now it
                         * is just a warning, so we won't suddenly break lpd
                         * for anyone who is currently using the option.
                         */
                        syslog(LOG_WARNING,
                            "NOTE: the -w option has been renamed -W");
                        syslog(LOG_WARNING,
                            "NOTE: please change your lpd config to use -W");
                        /* FALLTHROUGH */
                case 'F':
                        Fflag++;
                        break;
                case 'W':
                        /* allow connections coming from a non-reserved port */
                        /* (done by some lpr-implementations for MS-Windows) */ 
                        ch_options |= LPD_NOPORTCHK;
                        break;
                case '4':
                        family = PF_INET;
                        inet_flag++;
                        break;
                case '6':
#ifdef INET6
                        family = PF_INET6;
                        inet6_flag++;
#else
                        errx(EX_USAGE, "lpd compiled sans INET6 (IPv6 support)");
#endif
                        break;
                /*
                 * The following options are not in FreeBSD (yet?), but are
                 * listed here to "reserve" them, because the option-letters
                 * are used by either NetBSD or OpenBSD (as of July 2001).
                 */ 
                case 'b':               /* set bind-addr */
                case 'n':               /* set max num of children */
                case 'r':               /* allow 'of' for remote ptrs */
                                        /* ...[not needed in freebsd] */
                        /* FALLTHROUGH */
                default:
                        errs++;
                }
        if (inet_flag && inet6_flag)
                family = PF_UNSPEC;
        argc -= optind;
        argv += optind;
        if (errs)
                usage();

        if (argc == 1) {
                if ((i = atoi(argv[0])) == 0)
                        usage();
                if (i < 0 || i > USHRT_MAX)
                        errx(EX_USAGE, "port # %d is invalid", i);

                serv.s_port = htons(i);
                sp = &serv;
                argc--;
        } else {
                sp = getservbyname("printer", "tcp");
                if (sp == NULL)
                        errx(EX_OSFILE, "printer/tcp: unknown service");
        }

        if (argc != 0)
                usage();

        /*
         * We run chkprintcap right away to catch any errors and blat them
         * to stderr while we still have it open, rather than sending them
         * to syslog and leaving the user wondering why lpd started and
         * then stopped.  There should probably be a command-line flag to
         * ignore errors from chkprintcap.
         */
        {
                pid_t pid;
                int status;
                pid = fork();
                if (pid < 0) {
                        err(EX_OSERR, "cannot fork");
                } else if (pid == 0) {  /* child */
                        execl(_PATH_CHKPRINTCAP, _PATH_CHKPRINTCAP, (char *)0);
                        err(EX_OSERR, "cannot execute %s", _PATH_CHKPRINTCAP);
                }
                if (waitpid(pid, &status, 0) < 0) {
                        err(EX_OSERR, "cannot wait");
                }
                if (WIFEXITED(status) && WEXITSTATUS(status) != 0)
                        errx(EX_OSFILE, "%d errors in printcap file, exiting",
                             WEXITSTATUS(status));
        }

#ifdef DEBUG
        Fflag++;
#endif
        /*
         * Set up standard environment by detaching from the parent
         * if -F not specified
         */
        if (Fflag == 0) {
                daemon(0, 0);
        }

        openlog("lpd", LOG_PID, LOG_LPR);
        syslog(LOG_INFO, "lpd startup: logging=%d%s%s", lflag,
            socket_debug ? " dbg" : "", sflag ? " net-secure" : "");
        (void) umask(0);
        /*
         * NB: This depends on O_NONBLOCK semantics doing the right thing;
         * i.e., applying only to the O_EXLOCK and not to the rest of the
         * open/creation.  As of 1997-12-02, this is the case for commonly-
         * used filesystems.  There are other places in this code which
         * make the same assumption.
         */
        lfd = open(_PATH_MASTERLOCK, O_WRONLY|O_CREAT|O_EXLOCK|O_NONBLOCK,
                   LOCK_FILE_MODE);
        if (lfd < 0) {
                if (errno == EWOULDBLOCK)       /* active daemon present */
                        exit(0);
                syslog(LOG_ERR, "%s: %m", _PATH_MASTERLOCK);
                exit(1);
        }
        fcntl(lfd, F_SETFL, 0); /* turn off non-blocking mode */
        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", _PATH_MASTERLOCK);
                exit(1);
        }
        signal(SIGCHLD, reapchild);
        /*
         * Restart all the printers.
         */
        startup();
        (void) unlink(_PATH_SOCKETNAME);
        funix = socket(AF_UNIX, SOCK_STREAM, 0);
        if (funix < 0) {
                syslog(LOG_ERR, "socket: %m");
                exit(1);
        }

        sigemptyset(&nmask);
        sigaddset(&nmask, SIGHUP);
        sigaddset(&nmask, SIGINT);
        sigaddset(&nmask, SIGQUIT);
        sigaddset(&nmask, SIGTERM);
        sigprocmask(SIG_BLOCK, &nmask, &omask);

        (void) umask(077);
        signal(SIGHUP, mcleanup);
        signal(SIGINT, mcleanup);
        signal(SIGQUIT, mcleanup);
        signal(SIGTERM, mcleanup);
        memset(&un, 0, sizeof(un));
        un.sun_family = AF_UNIX;
        strcpy(un.sun_path, _PATH_SOCKETNAME);
#ifndef SUN_LEN
#define SUN_LEN(unp) (strlen((unp)->sun_path) + 2)
#endif
        if (bind(funix, (struct sockaddr *)&un, SUN_LEN(&un)) < 0) {
                syslog(LOG_ERR, "ubind: %m");
                exit(1);
        }
        (void) umask(0);
        sigprocmask(SIG_SETMASK, &omask, (sigset_t *)0);
        FD_ZERO(&defreadfds);
        FD_SET(funix, &defreadfds);
        listen(funix, 5);
        if (sflag == 0) {
                finet = socksetup(family, socket_debug);
        } else
                finet = NULL;   /* pretend we couldn't open TCP socket. */
        if (finet) {
                for (i = 1; i <= *finet; i++) {
                        FD_SET(finet[i], &defreadfds);
                        listen(finet[i], 5);
                }
        }
        /*
         * Main loop: accept, do a request, continue.
         */
        memset(&frominet, 0, sizeof(frominet));
        memset(&fromunix, 0, sizeof(fromunix));
        if (lflag)
                syslog(LOG_INFO, "lpd startup: ready to accept requests");
        /*
         * XXX - should be redone for multi-protocol
         */
        for (;;) {
                int domain, nfds, s;
                fd_set readfds;

                FD_COPY(&defreadfds, &readfds);
                nfds = select(20, &readfds, 0, 0, 0);
                if (nfds <= 0) {
                        if (nfds < 0 && errno != EINTR)
                                syslog(LOG_WARNING, "select: %m");
                        continue;
                }
                domain = -1;                /* avoid compile-time warning */
                s = -1;                     /* avoid compile-time warning */
                if (FD_ISSET(funix, &readfds)) {
                        domain = AF_UNIX, fromlen = sizeof(fromunix);
                        s = accept(funix,
                            (struct sockaddr *)&fromunix, &fromlen);
                } else {
                        for (i = 1; i <= *finet; i++) 
                                if (FD_ISSET(finet[i], &readfds)) {
                                        domain = AF_INET;
                                        fromlen = sizeof(frominet);
                                        s = accept(finet[i],
                                            (struct sockaddr *)&frominet,
                                            &fromlen);
                                }
                }
                if (s < 0) {
                        if (errno != EINTR)
                                syslog(LOG_WARNING, "accept: %m");
                        continue;
                }
                if (tv.tv_sec > 0) {
                        (void) setsockopt(s, SOL_SOCKET, SO_RCVTIMEO, &tv,
                            sizeof(tv));
                }
                if (fork() == 0) {
                        /*
                         * Note that printjob() also plays around with
                         * signal-handling routines, and may need to be
                         * changed when making changes to signal-handling.
                         */
                        signal(SIGCHLD, SIG_DFL);
                        signal(SIGHUP, SIG_IGN);
                        signal(SIGINT, SIG_IGN);
                        signal(SIGQUIT, SIG_IGN);
                        signal(SIGTERM, SIG_IGN);
                        (void) close(funix);
                        if (sflag == 0 && finet) {
                                for (i = 1; i <= *finet; i++) 
                                        (void)close(finet[i]);
                        }
                        dup2(s, STDOUT_FILENO);
                        (void) close(s);
                        if (domain == AF_INET) {
                                /* for both AF_INET and AF_INET6 */
                                from_remote = 1;
                                chkhost((struct sockaddr *)&frominet,
                                    ch_options);
                        } else
                                from_remote = 0;
                        doit();
                        exit(0);
                }
                (void) close(s);
        }
}

static void
reapchild(int signo __unused)
{
        int status;

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

static void
mcleanup(int signo)
{
        /*
         * XXX syslog(3) is not signal-safe.
         */
        if (lflag) {
                if (signo)
                        syslog(LOG_INFO, "exiting on signal %d", signo);
                else
                        syslog(LOG_INFO, "exiting");
        }
        unlink(_PATH_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 */

                 /* buffer to hold the client's machine-name */
static char      frombuf[MAXHOSTNAMELEN];
char    cbuf[BUFSIZ];           /* command line buffer */
const char      *cmdnames[] = {
        "null",
        "printjob",
        "recvjob",
        "displayq short",
        "displayq long",
        "rmjob"
};

static void
doit(void)
{
        char *cp, *printer;
        int n;
        int status;
        struct printer myprinter, *pp = &myprinter;

        init_printer(&myprinter);

        for (;;) {
                cp = cbuf;
                do {
                        if (cp >= &cbuf[sizeof(cbuf) - 1])
                                fatal(0, "Command line too long");
                        if ((n = read(STDOUT_FILENO, cp, 1)) != 1) {
                                if (n < 0)
                                        fatal(0, "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_host, cmdnames[(u_char)*cp], cp+1);
                        else
                                syslog(LOG_INFO, "bad request (%d) from %s",
                                        *cp, from_host);
                }
                switch (*cp++) {
                case CMD_CHECK_QUE: /* check the queue, print any jobs there */
                        startprinting(cp);
                        break;
                case CMD_TAKE_THIS: /* receive files to be queued */
                        if (!from_remote) {
                                syslog(LOG_INFO, "illegal request (%d)", *cp);
                                exit(1);
                        }
                        recvjob(cp);
                        break;
                case CMD_SHOWQ_SHORT: /* display the queue (short form) */
                case CMD_SHOWQ_LONG: /* display the queue (long form) */
                        /* XXX - this all needs to be redone. */
                        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(0, "Too many requests");
                                        requ[requests++] = atoi(cp);
                                } else {
                                        if (users >= MAXUSERS)
                                                fatal(0, "Too many users");
                                        user[users++] = cp;
                                }
                        }
                        status = getprintcap(printer, pp);
                        if (status < 0)
                                fatal(pp, "%s", pcaperr(status));
                        displayq(pp, cbuf[0] == CMD_SHOWQ_LONG);
                        exit(0);
                case CMD_RMJOB: /* remove a job from the queue */
                        if (!from_remote) {
                                syslog(LOG_INFO, "illegal request (%d)", *cp);
                                exit(1);
                        }
                        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(0, "Too many requests");
                                        requ[requests++] = atoi(cp);
                                } else {
                                        if (users >= MAXUSERS)
                                                fatal(0, "Too many users");
                                        user[users++] = cp;
                                }
                        }
                        rmjob(printer);
                        break;
                }
                fatal(0, "Illegal service request");
        }
}

/*
 * Make a pass through the printcap database and start printing any
 * files left from the last time the machine went down.
 */
static void
startup(void)
{
        int pid, status, more;
        struct printer myprinter, *pp = &myprinter;

        more = firstprinter(pp, &status);
        if (status)
                goto errloop;
        while (more) {
                if (ckqueue(pp) <= 0) {
                        goto next;
                }
                if (lflag)
                        syslog(LOG_INFO, "lpd startup: work for %s",
                            pp->printer);
                if ((pid = fork()) < 0) {
                        syslog(LOG_WARNING, "lpd startup: cannot fork for %s",
                            pp->printer);
                        mcleanup(0);
                }
                if (pid == 0) {
                        lastprinter();
                        printjob(pp);
                        /* NOTREACHED */
                }
                do {
next:
                        more = nextprinter(pp, &status);
errloop:
                        if (status)
                                syslog(LOG_WARNING, 
                                    "lpd startup: printcap entry for %s has errors, skipping",
                                    pp->printer ? pp->printer : "<noname?>");
                } while (more && status);
        }
}

/*
 * Make sure there's some work to do before forking off a child
 */
static int
ckqueue(struct printer *pp)
{
        register struct dirent *d;
        DIR *dirp;
        char *spooldir;

        spooldir = pp->spool_dir;
        if ((dirp = opendir(spooldir)) == NULL)
                return (-1);
        while ((d = readdir(dirp)) != NULL) {
                if (d->d_name[0] != 'c' || d->d_name[1] != 'f')
                        continue;       /* daemon control files only */
                closedir(dirp);
                return (1);             /* found something */
        }
        closedir(dirp);
        return (0);
}

#define DUMMY ":nobody::"

/*
 * Check to see if the host connecting to this host has access to any
 * lpd services on this host.
 */
static void
chkhost(struct sockaddr *f, int ch_opts)
{
        struct addrinfo hints, *res, *r;
        register FILE *hostf;
        char hostbuf[NI_MAXHOST], ip[NI_MAXHOST];
        char serv[NI_MAXSERV];
        char *syserr, *usererr;
        int error, errsav, fpass, good;

        from_host = ".na.";

        /* Need real hostname for temporary filenames */
        error = getnameinfo(f, f->sa_len, hostbuf, sizeof(hostbuf), NULL, 0,
            NI_NAMEREQD);
        if (error) {
                errsav = error;
                error = getnameinfo(f, f->sa_len, hostbuf, sizeof(hostbuf),
                    NULL, 0, NI_NUMERICHOST);
                if (error) {
                        asprintf(&syserr,
                            "can not determine hostname for remote host (%d,%d)",
                            errsav, error);
                        asprintf(&usererr,
                            "Host name for your address is not known");
                        fhosterr(ch_opts, syserr, usererr);
                        /* NOTREACHED */
                }
                asprintf(&syserr,
                    "Host name for remote host (%s) not known (%d)",
                    hostbuf, errsav);
                asprintf(&usererr,
                    "Host name for your address (%s) is not known",
                    hostbuf);
                fhosterr(ch_opts, syserr, usererr);
                /* NOTREACHED */
        }

        strlcpy(frombuf, hostbuf, sizeof(frombuf));
        from_host = frombuf;
        ch_opts |= LPD_ADDFROMLINE;

        /* Need address in stringform for comparison (no DNS lookup here) */
        error = getnameinfo(f, f->sa_len, hostbuf, sizeof(hostbuf), NULL, 0,
            NI_NUMERICHOST);
        if (error) {
                asprintf(&syserr, "Cannot print IP address (error %d)",
                    error);
                asprintf(&usererr, "Cannot print IP address for your host");
                fhosterr(ch_opts, syserr, usererr);
                /* NOTREACHED */
        }
        from_ip = strdup(hostbuf);

        /* Reject numeric addresses */
        memset(&hints, 0, sizeof(hints));
        hints.ai_family = family;
        hints.ai_socktype = SOCK_DGRAM; /*dummy*/
        hints.ai_flags = AI_PASSIVE | AI_NUMERICHOST;
        if (getaddrinfo(from_host, NULL, &hints, &res) == 0) {
                freeaddrinfo(res);
                /* This syslog message already includes from_host */
                ch_opts &= ~LPD_ADDFROMLINE;
                asprintf(&syserr, "reverse lookup results in non-FQDN %s",
                    from_host);
                /* same message to both syslog and remote user */
                fhosterr(ch_opts, syserr, syserr);
                /* NOTREACHED */
        }

        /* Check for spoof, ala rlogind */
        memset(&hints, 0, sizeof(hints));
        hints.ai_family = family;
        hints.ai_socktype = SOCK_DGRAM; /*dummy*/
        error = getaddrinfo(from_host, NULL, &hints, &res);
        if (error) {
                asprintf(&syserr, "dns lookup for address %s failed: %s",
                    from_ip, gai_strerror(error));
                asprintf(&usererr, "hostname for your address (%s) unknown: %s",
                    from_ip, gai_strerror(error));
                fhosterr(ch_opts, syserr, usererr);
                /* NOTREACHED */
        }
        good = 0;
        for (r = res; good == 0 && r; r = r->ai_next) {
                error = getnameinfo(r->ai_addr, r->ai_addrlen, ip, sizeof(ip),
                    NULL, 0, NI_NUMERICHOST);
                if (!error && !strcmp(from_ip, ip))
                        good = 1;
        }
        if (res)
                freeaddrinfo(res);
        if (good == 0) {
                asprintf(&syserr, "address for remote host (%s) not matched",
                    from_ip);
                asprintf(&usererr,
                    "address for your hostname (%s) not matched", from_ip);
                fhosterr(ch_opts, syserr, usererr);
                /* NOTREACHED */
        }

        fpass = 1;
        hostf = fopen(_PATH_HOSTSEQUIV, "r");
again:
        if (hostf) {
                if (__ivaliduser_sa(hostf, f, f->sa_len, DUMMY, DUMMY) == 0) {
                        (void) fclose(hostf);
                        goto foundhost;
                }
                (void) fclose(hostf);
        }
        if (fpass == 1) {
                fpass = 2;
                hostf = fopen(_PATH_HOSTSLPD, "r");
                goto again;
        }
        /* This syslog message already includes from_host */
        ch_opts &= ~LPD_ADDFROMLINE;
        asprintf(&syserr, "refused connection from %s, sip=%s", from_host,
            from_ip);
        asprintf(&usererr,
            "Print-services are not available to your host (%s).", from_host);
        fhosterr(ch_opts, syserr, usererr);
        /* NOTREACHED */

foundhost:
        if (ch_opts & LPD_NOPORTCHK)
                return;                 /* skip the reserved-port check */

        error = getnameinfo(f, f->sa_len, NULL, 0, serv, sizeof(serv),
            NI_NUMERICSERV);
        if (error) {
                /* same message to both syslog and remote user */
                asprintf(&syserr, "malformed from-address (%d)", error);
                fhosterr(ch_opts, syserr, syserr);
                /* NOTREACHED */
        }

        if (atoi(serv) >= IPPORT_RESERVED) {
                /* same message to both syslog and remote user */
                asprintf(&syserr, "connected from invalid port (%s)", serv);
                fhosterr(ch_opts, syserr, syserr);
                /* NOTREACHED */
        }
}

/*
 * Handle fatal errors in chkhost.  The first message will optionally be
 * sent to syslog, the second one is sent to the connecting host.
 *
 * The idea is that the syslog message is meant for an administrator of a
 * print server (the host receiving connections), while the usermsg is meant
 * for a remote user who may or may not be clueful, and may or may not be
 * doing something nefarious.  Some remote users (eg, MS-Windows...) may not
 * even see whatever message is sent, which is why there's the option to
 * start 'lpd' with the connection-errors also sent to syslog.
 *
 * Given that hostnames can theoretically be fairly long (well, over 250
 * bytes), it would probably be helpful to have the 'from_host' field at
 * the end of any error messages which include that info.
 *
 * These are Fatal host-connection errors, so this routine does not return.
 */
static void
fhosterr(int ch_opts, char *sysmsg, char *usermsg)
{

        /*
         * If lpd was started up to print connection errors, then write
         * the syslog message before the user message.
         * And for many of the syslog messages, it is helpful to first
         * write the from_host (if it is known) as a separate syslog
         * message, since the hostname may be so long.
         */
        if (ch_opts & LPD_LOGCONNERR) {
                if (ch_opts & LPD_ADDFROMLINE) {
                    syslog(LOG_WARNING, "for connection from %s:", from_host);
                }
                syslog(LOG_WARNING, "%s", sysmsg);
        }

        /*
         * Now send the error message to the remote host which is trying
         * to make the connection.
         */
        printf("%s [@%s]: %s\n", progname, local_host, usermsg);
        fflush(stdout);

        /* 
         * Add a minimal delay before exiting (and disconnecting from the
         * sending-host).  This is just in case that machine responds by
         * INSTANTLY retrying (and instantly re-failing...).  This may also
         * give the other side more time to read the error message.
         */
        sleep(2);                       /* a paranoid throttling measure */
        exit(1);
}

/* setup server socket for specified address family */
/* if af is PF_UNSPEC more than one socket may be returned */
/* the returned list is dynamically allocated, so caller needs to free it */
static int *
socksetup(int af, int debuglvl)
{
        struct addrinfo hints, *res, *r;
        int error, maxs, *s, *socks;
        const int on = 1;

        memset(&hints, 0, sizeof(hints));
        hints.ai_flags = AI_PASSIVE;
        hints.ai_family = af;
        hints.ai_socktype = SOCK_STREAM;
        error = getaddrinfo(NULL, "printer", &hints, &res);
        if (error) {
                syslog(LOG_ERR, "%s", gai_strerror(error));
                mcleanup(0);
        }

        /* Count max number of sockets we may open */
        for (maxs = 0, r = res; r; r = r->ai_next, maxs++)
                ;
        socks = malloc((maxs + 1) * sizeof(int));
        if (!socks) {
                syslog(LOG_ERR, "couldn't allocate memory for sockets");
                mcleanup(0);
        }

        *socks = 0;   /* num of sockets counter at start of array */
        s = socks + 1;
        for (r = res; r; r = r->ai_next) {
                *s = socket(r->ai_family, r->ai_socktype, r->ai_protocol);
                if (*s < 0) {
                        syslog(LOG_DEBUG, "socket(): %m");
                        continue;
                }
                if (setsockopt(*s, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on))
                    < 0) {
                        syslog(LOG_ERR, "setsockopt(SO_REUSEADDR): %m");
                        close(*s);
                        continue;
                }
                if (debuglvl)
                        if (setsockopt(*s, SOL_SOCKET, SO_DEBUG, &debuglvl,
                            sizeof(debuglvl)) < 0) {
                                syslog(LOG_ERR, "setsockopt (SO_DEBUG): %m");
                                close(*s);
                                continue;
                        }
                if (r->ai_family == AF_INET6) {
                        if (setsockopt(*s, IPPROTO_IPV6, IPV6_V6ONLY,
                                       &on, sizeof(on)) < 0) {
                                syslog(LOG_ERR,
                                       "setsockopt (IPV6_V6ONLY): %m");
                                close(*s);
                                continue;
                        }
                }
                if (bind(*s, r->ai_addr, r->ai_addrlen) < 0) {
                        syslog(LOG_DEBUG, "bind(): %m");
                        close(*s);
                        continue;
                }
                (*socks)++;
                s++;
        }

        if (res)
                freeaddrinfo(res);

        if (*socks == 0) {
                syslog(LOG_ERR, "Couldn't bind to any socket");
                free(socks);
                mcleanup(0);
        }
        return(socks);
}

static void
usage(void)
{
#ifdef INET6
        fprintf(stderr, "usage: lpd [-cdlsFW46] [port#]\n");
#else
        fprintf(stderr, "usage: lpd [-cdlsFW] [port#]\n");
#endif
        exit(EX_USAGE);
}