source: MondoRescue/branches/3.2/mindi-busybox/networking/inetd.c@ 3232

/* vi: set sw=4 ts=4: */
/*      $Slackware: inetd.c 1.79s 2001/02/06 13:18:00 volkerdi Exp $    */
/*      $OpenBSD: inetd.c,v 1.79 2001/01/30 08:30:57 deraadt Exp $      */
/*      $NetBSD: inetd.c,v 1.11 1996/02/22 11:14:41 mycroft Exp $       */
/* Busybox port by Vladimir Oleynik (C) 2001-2005 <dzo@simtreas.ru>     */
/* IPv6 support, many bug fixes by Denys Vlasenko (c) 2008 */
/*
 * Copyright (c) 1983,1991 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. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by the University of
 *      California, Berkeley and its contributors.
 * 4. 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.
 */

/* Inetd - Internet super-server
 *
 * This program invokes configured services when a connection
 * from a peer is established or a datagram arrives.
 * Connection-oriented services are invoked each time a
 * connection is made, by creating a process.  This process
 * is passed the connection as file descriptor 0 and is
 * expected to do a getpeername to find out peer's host
 * and port.
 * Datagram oriented services are invoked when a datagram
 * arrives; a process is created and passed a pending message
 * on file descriptor 0. peer's address can be obtained
 * using recvfrom.
 *
 * Inetd uses a configuration file which is read at startup
 * and, possibly, at some later time in response to a hangup signal.
 * The configuration file is "free format" with fields given in the
 * order shown below.  Continuation lines for an entry must begin with
 * a space or tab.  All fields must be present in each entry.
 *
 *      service_name                    must be in /etc/services
 *      socket_type                     stream/dgram/raw/rdm/seqpacket
 *      protocol                        must be in /etc/protocols
 *                                      (usually "tcp" or "udp")
 *      wait/nowait[.max]               single-threaded/multi-threaded, max #
 *      user[.group] or user[:group]    user/group to run daemon as
 *      server_program                  full path name
 *      server_program_arguments        maximum of MAXARGS (20)
 *
 * For RPC services
 *      service_name/version            must be in /etc/rpc
 *      socket_type                     stream/dgram/raw/rdm/seqpacket
 *      rpc/protocol                    "rpc/tcp" etc
 *      wait/nowait[.max]               single-threaded/multi-threaded
 *      user[.group] or user[:group]    user to run daemon as
 *      server_program                  full path name
 *      server_program_arguments        maximum of MAXARGS (20)
 *
 * For non-RPC services, the "service name" can be of the form
 * hostaddress:servicename, in which case the hostaddress is used
 * as the host portion of the address to listen on.  If hostaddress
 * consists of a single '*' character, INADDR_ANY is used.
 *
 * A line can also consist of just
 *      hostaddress:
 * where hostaddress is as in the preceding paragraph.  Such a line must
 * have no further fields; the specified hostaddress is remembered and
 * used for all further lines that have no hostaddress specified,
 * until the next such line (or EOF).  (This is why * is provided to
 * allow explicit specification of INADDR_ANY.)  A line
 *      *:
 * is implicitly in effect at the beginning of the file.
 *
 * The hostaddress specifier may (and often will) contain dots;
 * the service name must not.
 *
 * For RPC services, host-address specifiers are accepted and will
 * work to some extent; however, because of limitations in the
 * portmapper interface, it will not work to try to give more than
 * one line for any given RPC service, even if the host-address
 * specifiers are different.
 *
 * Comment lines are indicated by a '#' in column 1.
 */

/* inetd rules for passing file descriptors to children
 * (http://www.freebsd.org/cgi/man.cgi?query=inetd):
 *
 * The wait/nowait entry specifies whether the server that is invoked by
 * inetd will take over the socket associated with the service access point,
 * and thus whether inetd should wait for the server to exit before listen-
 * ing for new service requests.  Datagram servers must use "wait", as
 * they are always invoked with the original datagram socket bound to the
 * specified service address.  These servers must read at least one datagram
 * from the socket before exiting.  If a datagram server connects to its
 * peer, freeing the socket so inetd can receive further messages on the
 * socket, it is said to be a "multi-threaded" server; it should read one
 * datagram from the socket and create a new socket connected to the peer.
 * It should fork, and the parent should then exit to allow inetd to check
 * for new service requests to spawn new servers.  Datagram servers which
 * process all incoming datagrams on a socket and eventually time out are
 * said to be "single-threaded".  The comsat(8), biff(1) and talkd(8)
 * utilities are both examples of the latter type of datagram server.  The
 * tftpd(8) utility is an example of a multi-threaded datagram server.
 *
 * Servers using stream sockets generally are multi-threaded and use the
 * "nowait" entry. Connection requests for these services are accepted by
 * inetd, and the server is given only the newly-accepted socket connected
 * to a client of the service.  Most stream-based services operate in this
 * manner.  Stream-based servers that use "wait" are started with the lis-
 * tening service socket, and must accept at least one connection request
 * before exiting.  Such a server would normally accept and process incoming
 * connection requests until a timeout.
 */

/* Despite of above doc saying that dgram services must use "wait",
 * "udp nowait" servers are implemented in busyboxed inetd.
 * IPv6 addresses are also implemented. However, they may look ugly -
 * ":::service..." means "address '::' (IPv6 wildcard addr)":"service"...
 * You have to put "tcp6"/"udp6" in protocol field to select IPv6.
 */

/* Here's the scoop concerning the user[:group] feature:
 * 1) group is not specified:
 *      a) user = root: NO setuid() or setgid() is done
 *      b) other:       initgroups(name, primary group)
 *                      setgid(primary group as found in passwd)
 *                      setuid()
 * 2) group is specified:
 *      a) user = root: setgid(specified group)
 *                      NO initgroups()
 *                      NO setuid()
 *      b) other:       initgroups(name, specified group)
 *                      setgid(specified group)
 *                      setuid()
 */

//usage:#define inetd_trivial_usage
//usage:       "[-fe] [-q N] [-R N] [CONFFILE]"
//usage:#define inetd_full_usage "\n\n"
//usage:       "Listen for network connections and launch programs\n"
//usage:     "\n    -f  Run in foreground"
//usage:     "\n    -e  Log to stderr"
//usage:     "\n    -q N    Socket listen queue (default: 128)"
//usage:     "\n    -R N    Pause services after N connects/min"
//usage:     "\n        (default: 0 - disabled)"

#include <syslog.h>
#include <sys/resource.h> /* setrlimit */
#include <sys/socket.h> /* un.h may need this */
#include <sys/un.h>

#include "libbb.h"

#if ENABLE_FEATURE_INETD_RPC
# if defined(__UCLIBC__) && ! defined(__UCLIBC_HAS_RPC__)
#  error "You need to build uClibc with UCLIBC_HAS_RPC for NFS support"
# endif
# include <rpc/rpc.h>
# include <rpc/pmap_clnt.h>
#endif

#if !BB_MMU
/* stream version of chargen is forking but not execing,
 * can't do that (easily) on NOMMU */
#undef  ENABLE_FEATURE_INETD_SUPPORT_BUILTIN_CHARGEN
#define ENABLE_FEATURE_INETD_SUPPORT_BUILTIN_CHARGEN 0
#endif

#define CNT_INTERVAL    60      /* servers in CNT_INTERVAL sec. */
#define RETRYTIME       60      /* retry after bind or server fail */

// TODO: explain, or get rid of setrlimit games

#ifndef RLIMIT_NOFILE
#define RLIMIT_NOFILE   RLIMIT_OFILE
#endif

#ifndef OPEN_MAX
#define OPEN_MAX        64
#endif

/* Reserve some descriptors, 3 stdio + at least: 1 log, 1 conf. file */
#define FD_MARGIN       8

#if ENABLE_FEATURE_INETD_SUPPORT_BUILTIN_DISCARD \
 || ENABLE_FEATURE_INETD_SUPPORT_BUILTIN_ECHO    \
 || ENABLE_FEATURE_INETD_SUPPORT_BUILTIN_CHARGEN \
 || ENABLE_FEATURE_INETD_SUPPORT_BUILTIN_TIME    \
 || ENABLE_FEATURE_INETD_SUPPORT_BUILTIN_DAYTIME
# define INETD_BUILTINS_ENABLED
#endif

typedef struct servtab_t {
    /* The most frequently referenced one: */
    int se_fd;                            /* open descriptor */
    /* NB: 'biggest fields last' saves on code size (~250 bytes) */
    /* [addr:]service socktype proto wait user[:group] prog [args] */
    char *se_local_hostname;              /* addr to listen on */
    char *se_service;                     /* "80" or "www" or "mount/2[-3]" */
    /* socktype is in se_socktype */      /* "stream" "dgram" "raw" "rdm" "seqpacket" */
    char *se_proto;                       /* "unix" or "[rpc/]tcp[6]" */
#if ENABLE_FEATURE_INETD_RPC
    int se_rpcprog;                       /* rpc program number */
    int se_rpcver_lo;                     /* rpc program lowest version */
    int se_rpcver_hi;                     /* rpc program highest version */
#define is_rpc_service(sep)       ((sep)->se_rpcver_lo != 0)
#else
#define is_rpc_service(sep)       0
#endif
    pid_t se_wait;                        /* 0:"nowait", 1:"wait", >1:"wait" */
                                          /* and waiting for this pid */
    socktype_t se_socktype;               /* SOCK_STREAM/DGRAM/RDM/... */
    family_t se_family;                   /* AF_UNIX/INET[6] */
    /* se_proto_no is used by RPC code only... hmm */
    smallint se_proto_no;                 /* IPPROTO_TCP/UDP, n/a for AF_UNIX */
    smallint se_checked;                  /* looked at during merge */
    unsigned se_max;                      /* allowed instances per minute */
    unsigned se_count;                    /* number started since se_time */
    unsigned se_time;                     /* when we started counting */
    char *se_user;                        /* user name to run as */
    char *se_group;                       /* group name to run as, can be NULL */
#ifdef INETD_BUILTINS_ENABLED
    const struct builtin *se_builtin;     /* if built-in, description */
#endif
    struct servtab_t *se_next;
    len_and_sockaddr *se_lsa;
    char *se_program;                     /* server program */
#define MAXARGV 20
    char *se_argv[MAXARGV + 1];           /* program arguments */
} servtab_t;

#ifdef INETD_BUILTINS_ENABLED
/* Echo received data */
#if ENABLE_FEATURE_INETD_SUPPORT_BUILTIN_ECHO
static void FAST_FUNC echo_stream(int, servtab_t *);
static void FAST_FUNC echo_dg(int, servtab_t *);
#endif
/* Internet /dev/null */
#if ENABLE_FEATURE_INETD_SUPPORT_BUILTIN_DISCARD
static void FAST_FUNC discard_stream(int, servtab_t *);
static void FAST_FUNC discard_dg(int, servtab_t *);
#endif
/* Return 32 bit time since 1900 */
#if ENABLE_FEATURE_INETD_SUPPORT_BUILTIN_TIME
static void FAST_FUNC machtime_stream(int, servtab_t *);
static void FAST_FUNC machtime_dg(int, servtab_t *);
#endif
/* Return human-readable time */
#if ENABLE_FEATURE_INETD_SUPPORT_BUILTIN_DAYTIME
static void FAST_FUNC daytime_stream(int, servtab_t *);
static void FAST_FUNC daytime_dg(int, servtab_t *);
#endif
/* Familiar character generator */
#if ENABLE_FEATURE_INETD_SUPPORT_BUILTIN_CHARGEN
static void FAST_FUNC chargen_stream(int, servtab_t *);
static void FAST_FUNC chargen_dg(int, servtab_t *);
#endif

struct builtin {
    /* NB: not necessarily NUL terminated */
    char bi_service7[7];      /* internally provided service name */
    uint8_t bi_fork;          /* 1 if stream fn should run in child */
    void (*bi_stream_fn)(int, servtab_t *) FAST_FUNC;
    void (*bi_dgram_fn)(int, servtab_t *) FAST_FUNC;
};

static const struct builtin builtins[] = {
#if ENABLE_FEATURE_INETD_SUPPORT_BUILTIN_ECHO
    { "echo", 1, echo_stream, echo_dg },
#endif
#if ENABLE_FEATURE_INETD_SUPPORT_BUILTIN_DISCARD
    { "discard", 1, discard_stream, discard_dg },
#endif
#if ENABLE_FEATURE_INETD_SUPPORT_BUILTIN_CHARGEN
    { "chargen", 1, chargen_stream, chargen_dg },
#endif
#if ENABLE_FEATURE_INETD_SUPPORT_BUILTIN_TIME
    { "time", 0, machtime_stream, machtime_dg },
#endif
#if ENABLE_FEATURE_INETD_SUPPORT_BUILTIN_DAYTIME
    { "daytime", 0, daytime_stream, daytime_dg },
#endif
};
#endif /* INETD_BUILTINS_ENABLED */

struct globals {
    rlim_t rlim_ofile_cur;
    struct rlimit rlim_ofile;
    servtab_t *serv_list;
    int global_queuelen;
    int maxsock;         /* max fd# in allsock, -1: unknown */
    /* whenever maxsock grows, prev_maxsock is set to new maxsock,
     * but if maxsock is set to -1, prev_maxsock is not changed */
    int prev_maxsock;
    unsigned max_concurrency;
    smallint alarm_armed;
    uid_t real_uid; /* user ID who ran us */
    const char *config_filename;
    parser_t *parser;
    char *default_local_hostname;
#if ENABLE_FEATURE_INETD_SUPPORT_BUILTIN_CHARGEN
    char *end_ring;
    char *ring_pos;
    char ring[128];
#endif
    fd_set allsock;
    /* Used in next_line(), and as scratch read buffer */
    char line[256];          /* _at least_ 256, see LINE_SIZE */
} FIX_ALIASING;
#define G (*(struct globals*)&bb_common_bufsiz1)
enum { LINE_SIZE = COMMON_BUFSIZE - offsetof(struct globals, line) };
struct BUG_G_too_big {
    char BUG_G_too_big[sizeof(G) <= COMMON_BUFSIZE ? 1 : -1];
};
#define rlim_ofile_cur  (G.rlim_ofile_cur )
#define rlim_ofile      (G.rlim_ofile     )
#define serv_list       (G.serv_list      )
#define global_queuelen (G.global_queuelen)
#define maxsock         (G.maxsock        )
#define prev_maxsock    (G.prev_maxsock   )
#define max_concurrency (G.max_concurrency)
#define alarm_armed     (G.alarm_armed    )
#define real_uid        (G.real_uid       )
#define config_filename (G.config_filename)
#define parser          (G.parser         )
#define default_local_hostname (G.default_local_hostname)
#define first_ps_byte   (G.first_ps_byte  )
#define last_ps_byte    (G.last_ps_byte   )
#define end_ring        (G.end_ring       )
#define ring_pos        (G.ring_pos       )
#define ring            (G.ring           )
#define allsock         (G.allsock        )
#define line            (G.line           )
#define INIT_G() do { \
    rlim_ofile_cur = OPEN_MAX; \
    global_queuelen = 128; \
    config_filename = "/etc/inetd.conf"; \
} while (0)

#if 1
# define dbg(...) ((void)0)
#else
# define dbg(...) \
do { \
    int dbg_fd = open("inetd_debug.log", O_WRONLY | O_CREAT | O_APPEND, 0666); \
    if (dbg_fd >= 0) { \
        fdprintf(dbg_fd, "%d: ", getpid()); \
        fdprintf(dbg_fd, __VA_ARGS__); \
        close(dbg_fd); \
    } \
} while (0)
#endif

static void maybe_close(int fd)
{
    if (fd >= 0) {
        close(fd);
        dbg("closed fd:%d\n", fd);
    }
}

// TODO: move to libbb?
static len_and_sockaddr *xzalloc_lsa(int family)
{
    len_and_sockaddr *lsa;
    int sz;

    sz = sizeof(struct sockaddr_in);
    if (family == AF_UNIX)
        sz = sizeof(struct sockaddr_un);
#if ENABLE_FEATURE_IPV6
    if (family == AF_INET6)
        sz = sizeof(struct sockaddr_in6);
#endif
    lsa = xzalloc(LSA_LEN_SIZE + sz);
    lsa->len = sz;
    lsa->u.sa.sa_family = family;
    return lsa;
}

static void rearm_alarm(void)
{
    if (!alarm_armed) {
        alarm_armed = 1;
        alarm(RETRYTIME);
    }
}

static void block_CHLD_HUP_ALRM(sigset_t *m)
{
    sigemptyset(m);
    sigaddset(m, SIGCHLD);
    sigaddset(m, SIGHUP);
    sigaddset(m, SIGALRM);
    sigprocmask(SIG_BLOCK, m, m); /* old sigmask is stored in m */
}

static void restore_sigmask(sigset_t *m)
{
    sigprocmask(SIG_SETMASK, m, NULL);
}

#if ENABLE_FEATURE_INETD_RPC
static void register_rpc(servtab_t *sep)
{
    int n;
    struct sockaddr_in ir_sin;
    socklen_t size;

    size = sizeof(ir_sin);
    if (getsockname(sep->se_fd, (struct sockaddr *) &ir_sin, &size) < 0) {
        bb_perror_msg("getsockname");
        return;
    }

    for (n = sep->se_rpcver_lo; n <= sep->se_rpcver_hi; n++) {
        pmap_unset(sep->se_rpcprog, n);
        if (!pmap_set(sep->se_rpcprog, n, sep->se_proto_no, ntohs(ir_sin.sin_port)))
            bb_perror_msg("%s %s: pmap_set(%u,%u,%u,%u)",
                sep->se_service, sep->se_proto,
                sep->se_rpcprog, n, sep->se_proto_no, ntohs(ir_sin.sin_port));
    }
}

static void unregister_rpc(servtab_t *sep)
{
    int n;

    for (n = sep->se_rpcver_lo; n <= sep->se_rpcver_hi; n++) {
        if (!pmap_unset(sep->se_rpcprog, n))
            bb_perror_msg("pmap_unset(%u,%u)", sep->se_rpcprog, n);
    }
}
#endif /* FEATURE_INETD_RPC */

static void bump_nofile(void)
{
    enum { FD_CHUNK = 32 };
    struct rlimit rl;

    /* Never fails under Linux (except if you pass it bad arguments) */
    getrlimit(RLIMIT_NOFILE, &rl);
    rl.rlim_cur = MIN(rl.rlim_max, rl.rlim_cur + FD_CHUNK);
    rl.rlim_cur = MIN(FD_SETSIZE, rl.rlim_cur + FD_CHUNK);
    if (rl.rlim_cur <= rlim_ofile_cur) {
        bb_error_msg("can't extend file limit, max = %d",
                        (int) rl.rlim_cur);
        return;
    }

    if (setrlimit(RLIMIT_NOFILE, &rl) < 0) {
        bb_perror_msg("setrlimit");
        return;
    }

    rlim_ofile_cur = rl.rlim_cur;
}

static void remove_fd_from_set(int fd)
{
    if (fd >= 0) {
        FD_CLR(fd, &allsock);
        dbg("stopped listening on fd:%d\n", fd);
        maxsock = -1;
        dbg("maxsock:%d\n", maxsock);
    }
}

static void add_fd_to_set(int fd)
{
    if (fd >= 0) {
        FD_SET(fd, &allsock);
        dbg("started listening on fd:%d\n", fd);
        if (maxsock >= 0 && fd > maxsock) {
            prev_maxsock = maxsock = fd;
            dbg("maxsock:%d\n", maxsock);
            if ((rlim_t)fd > rlim_ofile_cur - FD_MARGIN)
                bump_nofile();
        }
    }
}

static void recalculate_maxsock(void)
{
    int fd = 0;

    /* We may have no services, in this case maxsock should still be >= 0
     * (code elsewhere is not happy with maxsock == -1) */
    maxsock = 0;
    while (fd <= prev_maxsock) {
        if (FD_ISSET(fd, &allsock))
            maxsock = fd;
        fd++;
    }
    dbg("recalculated maxsock:%d\n", maxsock);
    prev_maxsock = maxsock;
    if ((rlim_t)maxsock > rlim_ofile_cur - FD_MARGIN)
        bump_nofile();
}

static void prepare_socket_fd(servtab_t *sep)
{
    int r, fd;

    fd = socket(sep->se_family, sep->se_socktype, 0);
    if (fd < 0) {
        bb_perror_msg("socket");
        return;
    }
    setsockopt_reuseaddr(fd);

#if ENABLE_FEATURE_INETD_RPC
    if (is_rpc_service(sep)) {
        struct passwd *pwd;

        /* zero out the port for all RPC services; let bind()
         * find one. */
        set_nport(&sep->se_lsa->u.sa, 0);

        /* for RPC services, attempt to use a reserved port
         * if they are going to be running as root. */
        if (real_uid == 0 && sep->se_family == AF_INET
         && (pwd = getpwnam(sep->se_user)) != NULL
         && pwd->pw_uid == 0
        ) {
            r = bindresvport(fd, &sep->se_lsa->u.sin);
        } else {
            r = bind(fd, &sep->se_lsa->u.sa, sep->se_lsa->len);
        }
        if (r == 0) {
            int saveerrno = errno;
            /* update lsa with port# */
            getsockname(fd, &sep->se_lsa->u.sa, &sep->se_lsa->len);
            errno = saveerrno;
        }
    } else
#endif
    {
        if (sep->se_family == AF_UNIX) {
            struct sockaddr_un *sun;
            sun = (struct sockaddr_un*)&(sep->se_lsa->u.sa);
            unlink(sun->sun_path);
        }
        r = bind(fd, &sep->se_lsa->u.sa, sep->se_lsa->len);
    }
    if (r < 0) {
        bb_perror_msg("%s/%s: bind",
                sep->se_service, sep->se_proto);
        close(fd);
        rearm_alarm();
        return;
    }

    if (sep->se_socktype == SOCK_STREAM) {
        listen(fd, global_queuelen);
        dbg("new sep->se_fd:%d (stream)\n", fd);
    } else {
        dbg("new sep->se_fd:%d (!stream)\n", fd);
    }

    add_fd_to_set(fd);
    sep->se_fd = fd;
}

static int reopen_config_file(void)
{
    free(default_local_hostname);
    default_local_hostname = xstrdup("*");
    if (parser != NULL)
        config_close(parser);
    parser = config_open(config_filename);
    return (parser != NULL);
}

static void close_config_file(void)
{
    if (parser) {
        config_close(parser);
        parser = NULL;
    }
}

static void free_servtab_strings(servtab_t *cp)
{
    int i;

    free(cp->se_local_hostname);
    free(cp->se_service);
    free(cp->se_proto);
    free(cp->se_user);
    free(cp->se_group);
    free(cp->se_lsa); /* not a string in fact */
    free(cp->se_program);
    for (i = 0; i < MAXARGV; i++)
        free(cp->se_argv[i]);
}

static servtab_t *new_servtab(void)
{
    servtab_t *newtab = xzalloc(sizeof(servtab_t));
    newtab->se_fd = -1; /* paranoia */
    return newtab;
}

static servtab_t *dup_servtab(servtab_t *sep)
{
    servtab_t *newtab;
    int argc;

    newtab = new_servtab();
    *newtab = *sep; /* struct copy */
    /* deep-copying strings */
    newtab->se_service = xstrdup(newtab->se_service);
    newtab->se_proto = xstrdup(newtab->se_proto);
    newtab->se_user = xstrdup(newtab->se_user);
    newtab->se_group = xstrdup(newtab->se_group);
    newtab->se_program = xstrdup(newtab->se_program);
    for (argc = 0; argc <= MAXARGV; argc++)
        newtab->se_argv[argc] = xstrdup(newtab->se_argv[argc]);
    /* NB: se_fd, se_hostaddr and se_next are always
     * overwrittend by callers, so we don't bother resetting them
     * to NULL/0/-1 etc */

    return newtab;
}

/* gcc generates much more code if this is inlined */
static servtab_t *parse_one_line(void)
{
    int argc;
    char *token[6+MAXARGV];
    char *p, *arg;
    char *hostdelim;
    servtab_t *sep;
    servtab_t *nsep;
 new:
    sep = new_servtab();
 more:
    argc = config_read(parser, token, 6+MAXARGV, 1, "# \t", PARSE_NORMAL);
    if (!argc) {
        free(sep);
        return NULL;
    }

    /* [host:]service socktype proto wait user[:group] prog [args] */
    /* Check for "host:...." line */
    arg = token[0];
    hostdelim = strrchr(arg, ':');
    if (hostdelim) {
        *hostdelim = '\0';
        sep->se_local_hostname = xstrdup(arg);
        arg = hostdelim + 1;
        if (*arg == '\0' && argc == 1) {
            /* Line has just "host:", change the
             * default host for the following lines. */
            free(default_local_hostname);
            default_local_hostname = sep->se_local_hostname;
            goto more;
        }
    } else
        sep->se_local_hostname = xstrdup(default_local_hostname);

    /* service socktype proto wait user[:group] prog [args] */
    sep->se_service = xstrdup(arg);

    /* socktype proto wait user[:group] prog [args] */
    if (argc < 6) {
 parse_err:
        bb_error_msg("parse error on line %u, line is ignored",
                parser->lineno);
        free_servtab_strings(sep);
        /* Just "goto more" can make sep to carry over e.g.
         * "rpc"-ness (by having se_rpcver_lo != 0).
         * We will be more paranoid: */
        free(sep);
        goto new;
    }

    {
        static const int8_t SOCK_xxx[] ALIGN1 = {
            -1,
            SOCK_STREAM, SOCK_DGRAM, SOCK_RDM,
            SOCK_SEQPACKET, SOCK_RAW
        };
        sep->se_socktype = SOCK_xxx[1 + index_in_strings(
            "stream""\0" "dgram""\0" "rdm""\0"
            "seqpacket""\0" "raw""\0"
            , token[1])];
    }

    /* {unix,[rpc/]{tcp,udp}[6]} wait user[:group] prog [args] */
    sep->se_proto = arg = xstrdup(token[2]);
    if (strcmp(arg, "unix") == 0) {
        sep->se_family = AF_UNIX;
    } else {
        char *six;
        sep->se_family = AF_INET;
        six = last_char_is(arg, '6');
        if (six) {
#if ENABLE_FEATURE_IPV6
            *six = '\0';
            sep->se_family = AF_INET6;
#else
            bb_error_msg("%s: no support for IPv6", sep->se_proto);
            goto parse_err;
#endif
        }
        if (strncmp(arg, "rpc/", 4) == 0) {
#if ENABLE_FEATURE_INETD_RPC
            unsigned n;
            arg += 4;
            p = strchr(sep->se_service, '/');
            if (p == NULL) {
                bb_error_msg("no rpc version: '%s'", sep->se_service);
                goto parse_err;
            }
            *p++ = '\0';
            n = bb_strtou(p, &p, 10);
            if (n > INT_MAX) {
 bad_ver_spec:
                bb_error_msg("bad rpc version");
                goto parse_err;
            }
            sep->se_rpcver_lo = sep->se_rpcver_hi = n;
            if (*p == '-') {
                p++;
                n = bb_strtou(p, &p, 10);
                if (n > INT_MAX || (int)n < sep->se_rpcver_lo)
                    goto bad_ver_spec;
                sep->se_rpcver_hi = n;
            }
            if (*p != '\0')
                goto bad_ver_spec;
#else
            bb_error_msg("no support for rpc services");
            goto parse_err;
#endif
        }
        /* we don't really need getprotobyname()! */
        if (strcmp(arg, "tcp") == 0)
            sep->se_proto_no = IPPROTO_TCP; /* = 6 */
        if (strcmp(arg, "udp") == 0)
            sep->se_proto_no = IPPROTO_UDP; /* = 17 */
        if (six)
            *six = '6';
        if (!sep->se_proto_no) /* not tcp/udp?? */
            goto parse_err;
    }

    /* [no]wait[.max] user[:group] prog [args] */
    arg = token[3];
    sep->se_max = max_concurrency;
    p = strchr(arg, '.');
    if (p) {
        *p++ = '\0';
        sep->se_max = bb_strtou(p, NULL, 10);
        if (errno)
            goto parse_err;
    }
    sep->se_wait = (arg[0] != 'n' || arg[1] != 'o');
    if (!sep->se_wait) /* "no" seen */
        arg += 2;
    if (strcmp(arg, "wait") != 0)
        goto parse_err;

    /* user[:group] prog [args] */
    sep->se_user = xstrdup(token[4]);
    arg = strchr(sep->se_user, '.');
    if (arg == NULL)
        arg = strchr(sep->se_user, ':');
    if (arg) {
        *arg++ = '\0';
        sep->se_group = xstrdup(arg);
    }

    /* prog [args] */
    sep->se_program = xstrdup(token[5]);
#ifdef INETD_BUILTINS_ENABLED
    if (strcmp(sep->se_program, "internal") == 0
     && strlen(sep->se_service) <= 7
     && (sep->se_socktype == SOCK_STREAM
         || sep->se_socktype == SOCK_DGRAM)
    ) {
        unsigned i;
        for (i = 0; i < ARRAY_SIZE(builtins); i++)
            if (strncmp(builtins[i].bi_service7, sep->se_service, 7) == 0)
                goto found_bi;
        bb_error_msg("unknown internal service %s", sep->se_service);
        goto parse_err;
 found_bi:
        sep->se_builtin = &builtins[i];
        /* stream builtins must be "nowait", dgram must be "wait" */
        if (sep->se_wait != (sep->se_socktype == SOCK_DGRAM))
            goto parse_err;
    }
#endif
    argc = 0;
    while ((arg = token[6+argc]) != NULL && argc < MAXARGV)
        sep->se_argv[argc++] = xstrdup(arg);
    /* Some inetd.conf files have no argv's, not even argv[0].
     * Fix them up.
     * (Technically, programs can be execed with argv[0] = NULL,
     * but many programs do not like that at all) */
    if (argc == 0)
        sep->se_argv[0] = xstrdup(sep->se_program);

    /* catch mixups. "<service> stream udp ..." == wtf */
    if (sep->se_socktype == SOCK_STREAM) {
        if (sep->se_proto_no == IPPROTO_UDP)
            goto parse_err;
    }
    if (sep->se_socktype == SOCK_DGRAM) {
        if (sep->se_proto_no == IPPROTO_TCP)
            goto parse_err;
    }

//  bb_info_msg(
//      "ENTRY[%s][%s][%s][%d][%d][%d][%d][%d][%s][%s][%s]",
//      sep->se_local_hostname, sep->se_service, sep->se_proto, sep->se_wait, sep->se_proto_no,
//      sep->se_max, sep->se_count, sep->se_time, sep->se_user, sep->se_group, sep->se_program);

    /* check if the hostname specifier is a comma separated list
     * of hostnames. we'll make new entries for each address. */
    while ((hostdelim = strrchr(sep->se_local_hostname, ',')) != NULL) {
        nsep = dup_servtab(sep);
        /* NUL terminate the hostname field of the existing entry,
         * and make a dup for the new entry. */
        *hostdelim++ = '\0';
        nsep->se_local_hostname = xstrdup(hostdelim);
        nsep->se_next = sep->se_next;
        sep->se_next = nsep;
    }

    /* was doing it here: */
    /* DNS resolution, create copies for each IP address */
    /* IPv6-ization destroyed it :( */

    return sep;
}

static servtab_t *insert_in_servlist(servtab_t *cp)
{
    servtab_t *sep;
    sigset_t omask;

    sep = new_servtab();
    *sep = *cp; /* struct copy */
    sep->se_fd = -1;
#if ENABLE_FEATURE_INETD_RPC
    sep->se_rpcprog = -1;
#endif
    block_CHLD_HUP_ALRM(&omask);
    sep->se_next = serv_list;
    serv_list = sep;
    restore_sigmask(&omask);
    return sep;
}

static int same_serv_addr_proto(servtab_t *old, servtab_t *new)
{
    if (strcmp(old->se_local_hostname, new->se_local_hostname) != 0)
        return 0;
    if (strcmp(old->se_service, new->se_service) != 0)
        return 0;
    if (strcmp(old->se_proto, new->se_proto) != 0)
        return 0;
    return 1;
}

static void reread_config_file(int sig UNUSED_PARAM)
{
    servtab_t *sep, *cp, **sepp;
    len_and_sockaddr *lsa;
    sigset_t omask;
    unsigned n;
    uint16_t port;
    int save_errno = errno;

    if (!reopen_config_file())
        goto ret;
    for (sep = serv_list; sep; sep = sep->se_next)
        sep->se_checked = 0;

    goto first_line;
    while (1) {
        if (cp == NULL) {
 first_line:
            cp = parse_one_line();
            if (cp == NULL)
                break;
        }
        for (sep = serv_list; sep; sep = sep->se_next)
            if (same_serv_addr_proto(sep, cp))
                goto equal_servtab;
        /* not an "equal" servtab */
        sep = insert_in_servlist(cp);
        goto after_check;
 equal_servtab:
        {
            int i;

            block_CHLD_HUP_ALRM(&omask);
#if ENABLE_FEATURE_INETD_RPC
            if (is_rpc_service(sep))
                unregister_rpc(sep);
            sep->se_rpcver_lo = cp->se_rpcver_lo;
            sep->se_rpcver_hi = cp->se_rpcver_hi;
#endif
            if (cp->se_wait == 0) {
                /* New config says "nowait". If old one
                 * was "wait", we currently may be waiting
                 * for a child (and not accepting connects).
                 * Stop waiting, start listening again.
                 * (if it's not true, this op is harmless) */
                add_fd_to_set(sep->se_fd);
            }
            sep->se_wait = cp->se_wait;
            sep->se_max = cp->se_max;
            /* string fields need more love - we don't want to leak them */
#define SWAP(type, a, b) do { type c = (type)a; a = (type)b; b = (type)c; } while (0)
            SWAP(char*, sep->se_user, cp->se_user);
            SWAP(char*, sep->se_group, cp->se_group);
            SWAP(char*, sep->se_program, cp->se_program);
            for (i = 0; i < MAXARGV; i++)
                SWAP(char*, sep->se_argv[i], cp->se_argv[i]);
#undef SWAP
            restore_sigmask(&omask);
            free_servtab_strings(cp);
        }
 after_check:
        /* cp->string_fields are consumed by insert_in_servlist()
         * or freed at this point, cp itself is not yet freed. */
        sep->se_checked = 1;

        /* create new len_and_sockaddr */
        switch (sep->se_family) {
            struct sockaddr_un *sun;
        case AF_UNIX:
            lsa = xzalloc_lsa(AF_UNIX);
            sun = (struct sockaddr_un*)&lsa->u.sa;
            safe_strncpy(sun->sun_path, sep->se_service, sizeof(sun->sun_path));
            break;

        default: /* case AF_INET, case AF_INET6 */
            n = bb_strtou(sep->se_service, NULL, 10);
#if ENABLE_FEATURE_INETD_RPC
            if (is_rpc_service(sep)) {
                sep->se_rpcprog = n;
                if (errno) { /* se_service is not numeric */
                    struct rpcent *rp = getrpcbyname(sep->se_service);
                    if (rp == NULL) {
                        bb_error_msg("%s: unknown rpc service", sep->se_service);
                        goto next_cp;
                    }
                    sep->se_rpcprog = rp->r_number;
                }
                if (sep->se_fd == -1)
                    prepare_socket_fd(sep);
                if (sep->se_fd != -1)
                    register_rpc(sep);
                goto next_cp;
            }
#endif
            /* what port to listen on? */
            port = htons(n);
            if (errno || n > 0xffff) { /* se_service is not numeric */
                char protoname[4];
                struct servent *sp;
                /* can result only in "tcp" or "udp": */
                safe_strncpy(protoname, sep->se_proto, 4);
                sp = getservbyname(sep->se_service, protoname);
                if (sp == NULL) {
                    bb_error_msg("%s/%s: unknown service",
                            sep->se_service, sep->se_proto);
                    goto next_cp;
                }
                port = sp->s_port;
            }
            if (LONE_CHAR(sep->se_local_hostname, '*')) {
                lsa = xzalloc_lsa(sep->se_family);
                set_nport(&lsa->u.sa, port);
            } else {
                lsa = host_and_af2sockaddr(sep->se_local_hostname,
                        ntohs(port), sep->se_family);
                if (!lsa) {
                    bb_error_msg("%s/%s: unknown host '%s'",
                        sep->se_service, sep->se_proto,
                        sep->se_local_hostname);
                    goto next_cp;
                }
            }
            break;
        } /* end of "switch (sep->se_family)" */

        /* did lsa change? Then close/open */
        if (sep->se_lsa == NULL
         || lsa->len != sep->se_lsa->len
         || memcmp(&lsa->u.sa, &sep->se_lsa->u.sa, lsa->len) != 0
        ) {
            remove_fd_from_set(sep->se_fd);
            maybe_close(sep->se_fd);
            free(sep->se_lsa);
            sep->se_lsa = lsa;
            sep->se_fd = -1;
        } else {
            free(lsa);
        }
        if (sep->se_fd == -1)
            prepare_socket_fd(sep);
 next_cp:
        sep = cp->se_next;
        free(cp);
        cp = sep;
    } /* end of "while (1) parse lines" */
    close_config_file();

    /* Purge anything not looked at above - these are stale entries,
     * new config file doesnt have them. */
    block_CHLD_HUP_ALRM(&omask);
    sepp = &serv_list;
    while ((sep = *sepp) != NULL) {
        if (sep->se_checked) {
            sepp = &sep->se_next;
            continue;
        }
        *sepp = sep->se_next;
        remove_fd_from_set(sep->se_fd);
        maybe_close(sep->se_fd);
#if ENABLE_FEATURE_INETD_RPC
        if (is_rpc_service(sep))
            unregister_rpc(sep);
#endif
        if (sep->se_family == AF_UNIX)
            unlink(sep->se_service);
        free_servtab_strings(sep);
        free(sep);
    }
    restore_sigmask(&omask);
 ret:
    errno = save_errno;
}

static void reap_child(int sig UNUSED_PARAM)
{
    pid_t pid;
    int status;
    servtab_t *sep;
    int save_errno = errno;

    for (;;) {
        pid = wait_any_nohang(&status);
        if (pid <= 0)
            break;
        for (sep = serv_list; sep; sep = sep->se_next) {
            if (sep->se_wait != pid)
                continue;
            /* One of our "wait" services */
            if (WIFEXITED(status) && WEXITSTATUS(status))
                bb_error_msg("%s: exit status %u",
                        sep->se_program, WEXITSTATUS(status));
            else if (WIFSIGNALED(status))
                bb_error_msg("%s: exit signal %u",
                        sep->se_program, WTERMSIG(status));
            sep->se_wait = 1;
            add_fd_to_set(sep->se_fd);
            break;
        }
    }
    errno = save_errno;
}

static void retry_network_setup(int sig UNUSED_PARAM)
{
    int save_errno = errno;
    servtab_t *sep;

    alarm_armed = 0;
    for (sep = serv_list; sep; sep = sep->se_next) {
        if (sep->se_fd == -1) {
            prepare_socket_fd(sep);
#if ENABLE_FEATURE_INETD_RPC
            if (sep->se_fd != -1 && is_rpc_service(sep))
                register_rpc(sep);
#endif
        }
    }
    errno = save_errno;
}

static void clean_up_and_exit(int sig UNUSED_PARAM)
{
    servtab_t *sep;

    /* XXX signal race walking sep list */
    for (sep = serv_list; sep; sep = sep->se_next) {
        if (sep->se_fd == -1)
            continue;

        switch (sep->se_family) {
        case AF_UNIX:
            unlink(sep->se_service);
            break;
        default: /* case AF_INET, AF_INET6 */
#if ENABLE_FEATURE_INETD_RPC
            if (sep->se_wait == 1 && is_rpc_service(sep))
                unregister_rpc(sep);   /* XXX signal race */
#endif
            break;
        }
        if (ENABLE_FEATURE_CLEAN_UP)
            close(sep->se_fd);
    }
    remove_pidfile(CONFIG_PID_FILE_PATH "/inetd.pid");
    exit(EXIT_SUCCESS);
}

int inetd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int inetd_main(int argc UNUSED_PARAM, char **argv)
{
    struct sigaction sa, saved_pipe_handler;
    servtab_t *sep, *sep2;
    struct passwd *pwd;
    struct group *grp = grp; /* for compiler */
    int opt;
    pid_t pid;
    sigset_t omask;

    INIT_G();

    real_uid = getuid();
    if (real_uid != 0) /* run by non-root user */
        config_filename = NULL;

    opt_complementary = "R+:q+"; /* -q N, -R N */
    opt = getopt32(argv, "R:feq:", &max_concurrency, &global_queuelen);
    argv += optind;
    //argc -= optind;
    if (argv[0])
        config_filename = argv[0];
    if (config_filename == NULL)
        bb_error_msg_and_die("non-root must specify config file");
    if (!(opt & 2))
        bb_daemonize_or_rexec(0, argv - optind);
    else
        bb_sanitize_stdio();
    if (!(opt & 4)) {
        /* LOG_NDELAY: connect to syslog daemon NOW.
         * Otherwise, we may open syslog socket
         * in vforked child, making opened fds and syslog()
         * internal state inconsistent.
         * This was observed to leak file descriptors. */
        openlog(applet_name, LOG_PID | LOG_NDELAY, LOG_DAEMON);
        logmode = LOGMODE_SYSLOG;
    }

    if (real_uid == 0) {
        /* run by root, ensure groups vector gets trashed */
        gid_t gid = getgid();
        setgroups(1, &gid);
    }

    write_pidfile(CONFIG_PID_FILE_PATH "/inetd.pid");

    /* never fails under Linux (except if you pass it bad arguments) */
    getrlimit(RLIMIT_NOFILE, &rlim_ofile);
    rlim_ofile_cur = rlim_ofile.rlim_cur;
    if (rlim_ofile_cur == RLIM_INFINITY)    /* ! */
        rlim_ofile_cur = OPEN_MAX;

    memset(&sa, 0, sizeof(sa));
    /*sigemptyset(&sa.sa_mask); - memset did it */
    sigaddset(&sa.sa_mask, SIGALRM);
    sigaddset(&sa.sa_mask, SIGCHLD);
    sigaddset(&sa.sa_mask, SIGHUP);
//FIXME: explain why no SA_RESTART
//FIXME: retry_network_setup is unsafe to run in signal handler (many reasons)!
    sa.sa_handler = retry_network_setup;
    sigaction_set(SIGALRM, &sa);
//FIXME: reread_config_file is unsafe to run in signal handler(many reasons)!
    sa.sa_handler = reread_config_file;
    sigaction_set(SIGHUP, &sa);
//FIXME: reap_child is unsafe to run in signal handler (uses stdio)!
    sa.sa_handler = reap_child;
    sigaction_set(SIGCHLD, &sa);
//FIXME: clean_up_and_exit is unsafe to run in signal handler (uses stdio)!
    sa.sa_handler = clean_up_and_exit;
    sigaction_set(SIGTERM, &sa);
    sa.sa_handler = clean_up_and_exit;
    sigaction_set(SIGINT, &sa);
    sa.sa_handler = SIG_IGN;
    sigaction(SIGPIPE, &sa, &saved_pipe_handler);

    reread_config_file(SIGHUP); /* load config from file */

    for (;;) {
        int ready_fd_cnt;
        int ctrl, accepted_fd, new_udp_fd;
        fd_set readable;

        if (maxsock < 0)
            recalculate_maxsock();

        readable = allsock; /* struct copy */
        /* if there are no fds to wait on, we will block
         * until signal wakes us up (maxsock == 0, but readable
         * never contains fds 0 and 1...) */
        ready_fd_cnt = select(maxsock + 1, &readable, NULL, NULL, NULL);
        if (ready_fd_cnt < 0) {
            if (errno != EINTR) {
                bb_perror_msg("select");
                sleep(1);
            }
            continue;
        }
        dbg("ready_fd_cnt:%d\n", ready_fd_cnt);

        for (sep = serv_list; ready_fd_cnt && sep; sep = sep->se_next) {
            if (sep->se_fd == -1 || !FD_ISSET(sep->se_fd, &readable))
                continue;

            dbg("ready fd:%d\n", sep->se_fd);
            ready_fd_cnt--;
            ctrl = sep->se_fd;
            accepted_fd = -1;
            new_udp_fd = -1;
            if (!sep->se_wait) {
                if (sep->se_socktype == SOCK_STREAM) {
                    ctrl = accepted_fd = accept(sep->se_fd, NULL, NULL);
                    dbg("accepted_fd:%d\n", accepted_fd);
                    if (ctrl < 0) {
                        if (errno != EINTR)
                            bb_perror_msg("accept (for %s)", sep->se_service);
                        continue;
                    }
                }
                /* "nowait" udp */
                if (sep->se_socktype == SOCK_DGRAM
                 && sep->se_family != AF_UNIX
                ) {
/* How udp "nowait" works:
 * child peeks at (received and buffered by kernel) UDP packet,
 * performs connect() on the socket so that it is linked only
 * to this peer. But this also affects parent, because descriptors
 * are shared after fork() a-la dup(). When parent performs
 * select(), it will see this descriptor connected to the peer (!)
 * and still readable, will act on it and mess things up
 * (can create many copies of same child, etc).
 * Parent must create and use new socket instead. */
                    new_udp_fd = socket(sep->se_family, SOCK_DGRAM, 0);
                    dbg("new_udp_fd:%d\n", new_udp_fd);
                    if (new_udp_fd < 0) { /* error: eat packet, forget about it */
 udp_err:
                        recv(sep->se_fd, line, LINE_SIZE, MSG_DONTWAIT);
                        continue;
                    }
                    setsockopt_reuseaddr(new_udp_fd);
                    /* TODO: better do bind after fork in parent,
                     * so that we don't have two wildcard bound sockets
                     * even for a brief moment? */
                    if (bind(new_udp_fd, &sep->se_lsa->u.sa, sep->se_lsa->len) < 0) {
                        dbg("bind(new_udp_fd) failed\n");
                        close(new_udp_fd);
                        goto udp_err;
                    }
                    dbg("bind(new_udp_fd) succeeded\n");
                }
            }

            block_CHLD_HUP_ALRM(&omask);
            pid = 0;
#ifdef INETD_BUILTINS_ENABLED
            /* do we need to fork? */
            if (sep->se_builtin == NULL
             || (sep->se_socktype == SOCK_STREAM
                 && sep->se_builtin->bi_fork))
#endif
            {
                if (sep->se_max != 0) {
                    if (++sep->se_count == 1)
                        sep->se_time = monotonic_sec();
                    else if (sep->se_count >= sep->se_max) {
                        unsigned now = monotonic_sec();
                        /* did we accumulate se_max connects too quickly? */
                        if (now - sep->se_time <= CNT_INTERVAL) {
                            bb_error_msg("%s/%s: too many connections, pausing",
                                    sep->se_service, sep->se_proto);
                            remove_fd_from_set(sep->se_fd);
                            close(sep->se_fd);
                            sep->se_fd = -1;
                            sep->se_count = 0;
                            rearm_alarm(); /* will revive it in RETRYTIME sec */
                            restore_sigmask(&omask);
                            maybe_close(new_udp_fd);
                            maybe_close(accepted_fd);
                            continue; /* -> check next fd in fd set */
                        }
                        sep->se_count = 0;
                    }
                }
                /* on NOMMU, streamed chargen
                 * builtin wouldn't work, but it is
                 * not allowed on NOMMU (ifdefed out) */
#ifdef INETD_BUILTINS_ENABLED
                if (BB_MMU && sep->se_builtin)
                    pid = fork();
                else
#endif
                    pid = vfork();

                if (pid < 0) { /* fork error */
                    bb_perror_msg("vfork"+1);
                    sleep(1);
                    restore_sigmask(&omask);
                    maybe_close(new_udp_fd);
                    maybe_close(accepted_fd);
                    continue; /* -> check next fd in fd set */
                }
                if (pid == 0)
                    pid--; /* -1: "we did fork and we are child" */
            }
            /* if pid == 0 here, we didn't fork */

            if (pid > 0) { /* parent */
                if (sep->se_wait) {
                    /* wait: we passed socket to child,
                     * will wait for child to terminate */
                    sep->se_wait = pid;
                    remove_fd_from_set(sep->se_fd);
                }
                if (new_udp_fd >= 0) {
                    /* udp nowait: child connected the socket,
                     * we created and will use new, unconnected one */
                    xmove_fd(new_udp_fd, sep->se_fd);
                    dbg("moved new_udp_fd:%d to sep->se_fd:%d\n", new_udp_fd, sep->se_fd);
                }
                restore_sigmask(&omask);
                maybe_close(accepted_fd);
                continue; /* -> check next fd in fd set */
            }

            /* we are either child or didn't fork at all */
#ifdef INETD_BUILTINS_ENABLED
            if (sep->se_builtin) {
                if (pid) { /* "pid" is -1: we did fork */
                    close(sep->se_fd); /* listening socket */
                    dbg("closed sep->se_fd:%d\n", sep->se_fd);
                    logmode = LOGMODE_NONE; /* make xwrite etc silent */
                }
                restore_sigmask(&omask);
                if (sep->se_socktype == SOCK_STREAM)
                    sep->se_builtin->bi_stream_fn(ctrl, sep);
                else
                    sep->se_builtin->bi_dgram_fn(ctrl, sep);
                if (pid) /* we did fork */
                    _exit(EXIT_FAILURE);
                maybe_close(accepted_fd);
                continue; /* -> check next fd in fd set */
            }
#endif
            /* child */
            setsid();
            /* "nowait" udp */
            if (new_udp_fd >= 0) {
                len_and_sockaddr *lsa;
                int r;

                close(new_udp_fd);
                dbg("closed new_udp_fd:%d\n", new_udp_fd);
                lsa = xzalloc_lsa(sep->se_family);
                /* peek at the packet and remember peer addr */
                r = recvfrom(ctrl, NULL, 0, MSG_PEEK|MSG_DONTWAIT,
                    &lsa->u.sa, &lsa->len);
                if (r < 0)
                    goto do_exit1;
                /* make this socket "connected" to peer addr:
                 * only packets from this peer will be recv'ed,
                 * and bare write()/send() will work on it */
                connect(ctrl, &lsa->u.sa, lsa->len);
                dbg("connected ctrl:%d to remote peer\n", ctrl);
                free(lsa);
            }
            /* prepare env and exec program */
            pwd = getpwnam(sep->se_user);
            if (pwd == NULL) {
                bb_error_msg("%s: no such %s", sep->se_user, "user");
                goto do_exit1;
            }
            if (sep->se_group && (grp = getgrnam(sep->se_group)) == NULL) {
                bb_error_msg("%s: no such %s", sep->se_group, "group");
                goto do_exit1;
            }
            if (real_uid != 0 && real_uid != pwd->pw_uid) {
                /* a user running private inetd */
                bb_error_msg("non-root must run services as himself");
                goto do_exit1;
            }
            if (pwd->pw_uid != 0) {
                if (sep->se_group)
                    pwd->pw_gid = grp->gr_gid;
                /* initgroups, setgid, setuid: */
                change_identity(pwd);
            } else if (sep->se_group) {
                xsetgid(grp->gr_gid);
                setgroups(1, &grp->gr_gid);
            }
            if (rlim_ofile.rlim_cur != rlim_ofile_cur)
                if (setrlimit(RLIMIT_NOFILE, &rlim_ofile) < 0)
                    bb_perror_msg("setrlimit");

            /* closelog(); - WRONG. we are after vfork,
             * this may confuse syslog() internal state.
             * Let's hope libc sets syslog fd to CLOEXEC...
             */
            xmove_fd(ctrl, STDIN_FILENO);
            xdup2(STDIN_FILENO, STDOUT_FILENO);
            dbg("moved ctrl:%d to fd 0,1[,2]\n", ctrl);
            /* manpages of inetd I managed to find either say
             * that stderr is also redirected to the network,
             * or do not talk about redirection at all (!) */
            if (!sep->se_wait) /* only for usual "tcp nowait" */
                xdup2(STDIN_FILENO, STDERR_FILENO);
            /* NB: among others, this loop closes listening sockets
             * for nowait stream children */
            for (sep2 = serv_list; sep2; sep2 = sep2->se_next)
                if (sep2->se_fd != ctrl)
                    maybe_close(sep2->se_fd);
            sigaction_set(SIGPIPE, &saved_pipe_handler);
            restore_sigmask(&omask);
            dbg("execing:'%s'\n", sep->se_program);
            BB_EXECVP(sep->se_program, sep->se_argv);
            bb_perror_msg("can't execute '%s'", sep->se_program);
 do_exit1:
            /* eat packet in udp case */
            if (sep->se_socktype != SOCK_STREAM)
                recv(0, line, LINE_SIZE, MSG_DONTWAIT);
            _exit(EXIT_FAILURE);
        } /* for (sep = servtab...) */
    } /* for (;;) */
}

#if !BB_MMU
static const char *const cat_args[] = { "cat", NULL };
#endif

/*
 * Internet services provided internally by inetd:
 */
#if ENABLE_FEATURE_INETD_SUPPORT_BUILTIN_ECHO
/* Echo service -- echo data back. */
/* ARGSUSED */
static void FAST_FUNC echo_stream(int s, servtab_t *sep UNUSED_PARAM)
{
#if BB_MMU
    while (1) {
        ssize_t sz = safe_read(s, line, LINE_SIZE);
        if (sz <= 0)
            break;
        xwrite(s, line, sz);
    }
#else
    /* We are after vfork here! */
    /* move network socket to stdin/stdout */
    xmove_fd(s, STDIN_FILENO);
    xdup2(STDIN_FILENO, STDOUT_FILENO);
    /* no error messages please... */
    close(STDERR_FILENO);
    xopen(bb_dev_null, O_WRONLY);
    BB_EXECVP("cat", (char**)cat_args);
    /* on failure we return to main, which does exit(EXIT_FAILURE) */
#endif
}
static void FAST_FUNC echo_dg(int s, servtab_t *sep)
{
    enum { BUFSIZE = 12*1024 }; /* for jumbo sized packets! :) */
    char *buf = xmalloc(BUFSIZE); /* too big for stack */
    int sz;
    len_and_sockaddr *lsa = alloca(LSA_LEN_SIZE + sep->se_lsa->len);

    lsa->len = sep->se_lsa->len;
    /* dgram builtins are non-forking - DONT BLOCK! */
    sz = recvfrom(s, buf, BUFSIZE, MSG_DONTWAIT, &lsa->u.sa, &lsa->len);
    if (sz > 0)
        sendto(s, buf, sz, 0, &lsa->u.sa, lsa->len);
    free(buf);
}
#endif  /* FEATURE_INETD_SUPPORT_BUILTIN_ECHO */


#if ENABLE_FEATURE_INETD_SUPPORT_BUILTIN_DISCARD
/* Discard service -- ignore data. */
/* ARGSUSED */
static void FAST_FUNC discard_stream(int s, servtab_t *sep UNUSED_PARAM)
{
#if BB_MMU
    while (safe_read(s, line, LINE_SIZE) > 0)
        continue;
#else
    /* We are after vfork here! */
    /* move network socket to stdin */
    xmove_fd(s, STDIN_FILENO);
    /* discard output */
    close(STDOUT_FILENO);
    xopen(bb_dev_null, O_WRONLY);
    /* no error messages please... */
    xdup2(STDOUT_FILENO, STDERR_FILENO);
    BB_EXECVP("cat", (char**)cat_args);
    /* on failure we return to main, which does exit(EXIT_FAILURE) */
#endif
}
/* ARGSUSED */
static void FAST_FUNC discard_dg(int s, servtab_t *sep UNUSED_PARAM)
{
    /* dgram builtins are non-forking - DONT BLOCK! */
    recv(s, line, LINE_SIZE, MSG_DONTWAIT);
}
#endif /* FEATURE_INETD_SUPPORT_BUILTIN_DISCARD */


#if ENABLE_FEATURE_INETD_SUPPORT_BUILTIN_CHARGEN
#define LINESIZ 72
static void init_ring(void)
{
    int i;

    end_ring = ring;
    for (i = ' '; i < 127; i++)
        *end_ring++ = i;
}
/* Character generator. MMU arches only. */
/* ARGSUSED */
static void FAST_FUNC chargen_stream(int s, servtab_t *sep UNUSED_PARAM)
{
    char *rs;
    int len;
    char text[LINESIZ + 2];

    if (!end_ring) {
        init_ring();
        rs = ring;
    }

    text[LINESIZ] = '\r';
    text[LINESIZ + 1] = '\n';
    rs = ring;
    for (;;) {
        len = end_ring - rs;
        if (len >= LINESIZ)
            memmove(text, rs, LINESIZ);
        else {
            memmove(text, rs, len);
            memmove(text + len, ring, LINESIZ - len);
        }
        if (++rs == end_ring)
            rs = ring;
        xwrite(s, text, sizeof(text));
    }
}
/* ARGSUSED */
static void FAST_FUNC chargen_dg(int s, servtab_t *sep)
{
    int len;
    char text[LINESIZ + 2];
    len_and_sockaddr *lsa = alloca(LSA_LEN_SIZE + sep->se_lsa->len);

    /* Eat UDP packet which started it all */
    /* dgram builtins are non-forking - DONT BLOCK! */
    lsa->len = sep->se_lsa->len;
    if (recvfrom(s, text, sizeof(text), MSG_DONTWAIT, &lsa->u.sa, &lsa->len) < 0)
        return;

    if (!end_ring) {
        init_ring();
        ring_pos = ring;
    }

    len = end_ring - ring_pos;
    if (len >= LINESIZ)
        memmove(text, ring_pos, LINESIZ);
    else {
        memmove(text, ring_pos, len);
        memmove(text + len, ring, LINESIZ - len);
    }
    if (++ring_pos == end_ring)
        ring_pos = ring;
    text[LINESIZ] = '\r';
    text[LINESIZ + 1] = '\n';
    sendto(s, text, sizeof(text), 0, &lsa->u.sa, lsa->len);
}
#endif /* FEATURE_INETD_SUPPORT_BUILTIN_CHARGEN */


#if ENABLE_FEATURE_INETD_SUPPORT_BUILTIN_TIME
/*
 * Return a machine readable date and time, in the form of the
 * number of seconds since midnight, Jan 1, 1900.  Since gettimeofday
 * returns the number of seconds since midnight, Jan 1, 1970,
 * we must add 2208988800 seconds to this figure to make up for
 * some seventy years Bell Labs was asleep.
 */
static uint32_t machtime(void)
{
    struct timeval tv;

    gettimeofday(&tv, NULL);
    return htonl((uint32_t)(tv.tv_sec + 2208988800));
}
/* ARGSUSED */
static void FAST_FUNC machtime_stream(int s, servtab_t *sep UNUSED_PARAM)
{
    uint32_t result;

    result = machtime();
    full_write(s, &result, sizeof(result));
}
static void FAST_FUNC machtime_dg(int s, servtab_t *sep)
{
    uint32_t result;
    len_and_sockaddr *lsa = alloca(LSA_LEN_SIZE + sep->se_lsa->len);

    lsa->len = sep->se_lsa->len;
    if (recvfrom(s, line, LINE_SIZE, MSG_DONTWAIT, &lsa->u.sa, &lsa->len) < 0)
        return;

    result = machtime();
    sendto(s, &result, sizeof(result), 0, &lsa->u.sa, lsa->len);
}
#endif /* FEATURE_INETD_SUPPORT_BUILTIN_TIME */


#if ENABLE_FEATURE_INETD_SUPPORT_BUILTIN_DAYTIME
/* Return human-readable time of day */
/* ARGSUSED */
static void FAST_FUNC daytime_stream(int s, servtab_t *sep UNUSED_PARAM)
{
    time_t t;

    t = time(NULL);
    fdprintf(s, "%.24s\r\n", ctime(&t));
}
static void FAST_FUNC daytime_dg(int s, servtab_t *sep)
{
    time_t t;
    len_and_sockaddr *lsa = alloca(LSA_LEN_SIZE + sep->se_lsa->len);

    lsa->len = sep->se_lsa->len;
    if (recvfrom(s, line, LINE_SIZE, MSG_DONTWAIT, &lsa->u.sa, &lsa->len) < 0)
        return;

    t = time(NULL);
    sprintf(line, "%.24s\r\n", ctime(&t));
    sendto(s, line, strlen(line), 0, &lsa->u.sa, lsa->len);
}
#endif /* FEATURE_INETD_SUPPORT_BUILTIN_DAYTIME */