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

Last change on this file since 3232 was 3232, checked in by bruno, 6 years ago
  • Update mindi-busybox to 1.21.1
File size: 49.2 KB
Line 
1/* vi: set sw=4 ts=4: */
2/*      $Slackware: inetd.c 1.79s 2001/02/06 13:18:00 volkerdi Exp $    */
3/*      $OpenBSD: inetd.c,v 1.79 2001/01/30 08:30:57 deraadt Exp $      */
4/*      $NetBSD: inetd.c,v 1.11 1996/02/22 11:14:41 mycroft Exp $       */
5/* Busybox port by Vladimir Oleynik (C) 2001-2005 <dzo@simtreas.ru>     */
6/* IPv6 support, many bug fixes by Denys Vlasenko (c) 2008 */
7/*
8 * Copyright (c) 1983,1991 The Regents of the University of California.
9 * All rights reserved.
10 *
11 * Redistribution and use in source and binary forms, with or without
12 * modification, are permitted provided that the following conditions
13 * are met:
14 * 1. Redistributions of source code must retain the above copyright
15 *    notice, this list of conditions and the following disclaimer.
16 * 2. Redistributions in binary form must reproduce the above copyright
17 *    notice, this list of conditions and the following disclaimer in the
18 *    documentation and/or other materials provided with the distribution.
19 * 3. All advertising materials mentioning features or use of this software
20 *    must display the following acknowledgement:
21 *      This product includes software developed by the University of
22 *      California, Berkeley and its contributors.
23 * 4. Neither the name of the University nor the names of its contributors
24 *    may be used to endorse or promote products derived from this software
25 *    without specific prior written permission.
26 *
27 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS "AS IS" AND
28 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
29 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
30 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
31 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
32 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
33 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
34 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
35 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
36 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
37 * SUCH DAMAGE.
38 */
39
40/* Inetd - Internet super-server
41 *
42 * This program invokes configured services when a connection
43 * from a peer is established or a datagram arrives.
44 * Connection-oriented services are invoked each time a
45 * connection is made, by creating a process.  This process
46 * is passed the connection as file descriptor 0 and is
47 * expected to do a getpeername to find out peer's host
48 * and port.
49 * Datagram oriented services are invoked when a datagram
50 * arrives; a process is created and passed a pending message
51 * on file descriptor 0. peer's address can be obtained
52 * using recvfrom.
53 *
54 * Inetd uses a configuration file which is read at startup
55 * and, possibly, at some later time in response to a hangup signal.
56 * The configuration file is "free format" with fields given in the
57 * order shown below.  Continuation lines for an entry must begin with
58 * a space or tab.  All fields must be present in each entry.
59 *
60 *      service_name                    must be in /etc/services
61 *      socket_type                     stream/dgram/raw/rdm/seqpacket
62 *      protocol                        must be in /etc/protocols
63 *                                      (usually "tcp" or "udp")
64 *      wait/nowait[.max]               single-threaded/multi-threaded, max #
65 *      user[.group] or user[:group]    user/group to run daemon as
66 *      server_program                  full path name
67 *      server_program_arguments        maximum of MAXARGS (20)
68 *
69 * For RPC services
70 *      service_name/version            must be in /etc/rpc
71 *      socket_type                     stream/dgram/raw/rdm/seqpacket
72 *      rpc/protocol                    "rpc/tcp" etc
73 *      wait/nowait[.max]               single-threaded/multi-threaded
74 *      user[.group] or user[:group]    user to run daemon as
75 *      server_program                  full path name
76 *      server_program_arguments        maximum of MAXARGS (20)
77 *
78 * For non-RPC services, the "service name" can be of the form
79 * hostaddress:servicename, in which case the hostaddress is used
80 * as the host portion of the address to listen on.  If hostaddress
81 * consists of a single '*' character, INADDR_ANY is used.
82 *
83 * A line can also consist of just
84 *      hostaddress:
85 * where hostaddress is as in the preceding paragraph.  Such a line must
86 * have no further fields; the specified hostaddress is remembered and
87 * used for all further lines that have no hostaddress specified,
88 * until the next such line (or EOF).  (This is why * is provided to
89 * allow explicit specification of INADDR_ANY.)  A line
90 *      *:
91 * is implicitly in effect at the beginning of the file.
92 *
93 * The hostaddress specifier may (and often will) contain dots;
94 * the service name must not.
95 *
96 * For RPC services, host-address specifiers are accepted and will
97 * work to some extent; however, because of limitations in the
98 * portmapper interface, it will not work to try to give more than
99 * one line for any given RPC service, even if the host-address
100 * specifiers are different.
101 *
102 * Comment lines are indicated by a '#' in column 1.
103 */
104
105/* inetd rules for passing file descriptors to children
106 * (http://www.freebsd.org/cgi/man.cgi?query=inetd):
107 *
108 * The wait/nowait entry specifies whether the server that is invoked by
109 * inetd will take over the socket associated with the service access point,
110 * and thus whether inetd should wait for the server to exit before listen-
111 * ing for new service requests.  Datagram servers must use "wait", as
112 * they are always invoked with the original datagram socket bound to the
113 * specified service address.  These servers must read at least one datagram
114 * from the socket before exiting.  If a datagram server connects to its
115 * peer, freeing the socket so inetd can receive further messages on the
116 * socket, it is said to be a "multi-threaded" server; it should read one
117 * datagram from the socket and create a new socket connected to the peer.
118 * It should fork, and the parent should then exit to allow inetd to check
119 * for new service requests to spawn new servers.  Datagram servers which
120 * process all incoming datagrams on a socket and eventually time out are
121 * said to be "single-threaded".  The comsat(8), biff(1) and talkd(8)
122 * utilities are both examples of the latter type of datagram server.  The
123 * tftpd(8) utility is an example of a multi-threaded datagram server.
124 *
125 * Servers using stream sockets generally are multi-threaded and use the
126 * "nowait" entry. Connection requests for these services are accepted by
127 * inetd, and the server is given only the newly-accepted socket connected
128 * to a client of the service.  Most stream-based services operate in this
129 * manner.  Stream-based servers that use "wait" are started with the lis-
130 * tening service socket, and must accept at least one connection request
131 * before exiting.  Such a server would normally accept and process incoming
132 * connection requests until a timeout.
133 */
134
135/* Despite of above doc saying that dgram services must use "wait",
136 * "udp nowait" servers are implemented in busyboxed inetd.
137 * IPv6 addresses are also implemented. However, they may look ugly -
138 * ":::service..." means "address '::' (IPv6 wildcard addr)":"service"...
139 * You have to put "tcp6"/"udp6" in protocol field to select IPv6.
140 */
141
142/* Here's the scoop concerning the user[:group] feature:
143 * 1) group is not specified:
144 *      a) user = root: NO setuid() or setgid() is done
145 *      b) other:       initgroups(name, primary group)
146 *                      setgid(primary group as found in passwd)
147 *                      setuid()
148 * 2) group is specified:
149 *      a) user = root: setgid(specified group)
150 *                      NO initgroups()
151 *                      NO setuid()
152 *      b) other:       initgroups(name, specified group)
153 *                      setgid(specified group)
154 *                      setuid()
155 */
156
157//usage:#define inetd_trivial_usage
158//usage:       "[-fe] [-q N] [-R N] [CONFFILE]"
159//usage:#define inetd_full_usage "\n\n"
160//usage:       "Listen for network connections and launch programs\n"
161//usage:     "\n    -f  Run in foreground"
162//usage:     "\n    -e  Log to stderr"
163//usage:     "\n    -q N    Socket listen queue (default: 128)"
164//usage:     "\n    -R N    Pause services after N connects/min"
165//usage:     "\n        (default: 0 - disabled)"
166
167#include <syslog.h>
168#include <sys/resource.h> /* setrlimit */
169#include <sys/socket.h> /* un.h may need this */
170#include <sys/un.h>
171
172#include "libbb.h"
173
174#if ENABLE_FEATURE_INETD_RPC
175# if defined(__UCLIBC__) && ! defined(__UCLIBC_HAS_RPC__)
176#  error "You need to build uClibc with UCLIBC_HAS_RPC for NFS support"
177# endif
178# include <rpc/rpc.h>
179# include <rpc/pmap_clnt.h>
180#endif
181
182#if !BB_MMU
183/* stream version of chargen is forking but not execing,
184 * can't do that (easily) on NOMMU */
185#undef  ENABLE_FEATURE_INETD_SUPPORT_BUILTIN_CHARGEN
186#define ENABLE_FEATURE_INETD_SUPPORT_BUILTIN_CHARGEN 0
187#endif
188
189#define CNT_INTERVAL    60      /* servers in CNT_INTERVAL sec. */
190#define RETRYTIME       60      /* retry after bind or server fail */
191
192// TODO: explain, or get rid of setrlimit games
193
194#ifndef RLIMIT_NOFILE
195#define RLIMIT_NOFILE   RLIMIT_OFILE
196#endif
197
198#ifndef OPEN_MAX
199#define OPEN_MAX        64
200#endif
201
202/* Reserve some descriptors, 3 stdio + at least: 1 log, 1 conf. file */
203#define FD_MARGIN       8
204
205#if ENABLE_FEATURE_INETD_SUPPORT_BUILTIN_DISCARD \
206 || ENABLE_FEATURE_INETD_SUPPORT_BUILTIN_ECHO    \
207 || ENABLE_FEATURE_INETD_SUPPORT_BUILTIN_CHARGEN \
208 || ENABLE_FEATURE_INETD_SUPPORT_BUILTIN_TIME    \
209 || ENABLE_FEATURE_INETD_SUPPORT_BUILTIN_DAYTIME
210# define INETD_BUILTINS_ENABLED
211#endif
212
213typedef struct servtab_t {
214    /* The most frequently referenced one: */
215    int se_fd;                            /* open descriptor */
216    /* NB: 'biggest fields last' saves on code size (~250 bytes) */
217    /* [addr:]service socktype proto wait user[:group] prog [args] */
218    char *se_local_hostname;              /* addr to listen on */
219    char *se_service;                     /* "80" or "www" or "mount/2[-3]" */
220    /* socktype is in se_socktype */      /* "stream" "dgram" "raw" "rdm" "seqpacket" */
221    char *se_proto;                       /* "unix" or "[rpc/]tcp[6]" */
222#if ENABLE_FEATURE_INETD_RPC
223    int se_rpcprog;                       /* rpc program number */
224    int se_rpcver_lo;                     /* rpc program lowest version */
225    int se_rpcver_hi;                     /* rpc program highest version */
226#define is_rpc_service(sep)       ((sep)->se_rpcver_lo != 0)
227#else
228#define is_rpc_service(sep)       0
229#endif
230    pid_t se_wait;                        /* 0:"nowait", 1:"wait", >1:"wait" */
231                                          /* and waiting for this pid */
232    socktype_t se_socktype;               /* SOCK_STREAM/DGRAM/RDM/... */
233    family_t se_family;                   /* AF_UNIX/INET[6] */
234    /* se_proto_no is used by RPC code only... hmm */
235    smallint se_proto_no;                 /* IPPROTO_TCP/UDP, n/a for AF_UNIX */
236    smallint se_checked;                  /* looked at during merge */
237    unsigned se_max;                      /* allowed instances per minute */
238    unsigned se_count;                    /* number started since se_time */
239    unsigned se_time;                     /* when we started counting */
240    char *se_user;                        /* user name to run as */
241    char *se_group;                       /* group name to run as, can be NULL */
242#ifdef INETD_BUILTINS_ENABLED
243    const struct builtin *se_builtin;     /* if built-in, description */
244#endif
245    struct servtab_t *se_next;
246    len_and_sockaddr *se_lsa;
247    char *se_program;                     /* server program */
248#define MAXARGV 20
249    char *se_argv[MAXARGV + 1];           /* program arguments */
250} servtab_t;
251
252#ifdef INETD_BUILTINS_ENABLED
253/* Echo received data */
254#if ENABLE_FEATURE_INETD_SUPPORT_BUILTIN_ECHO
255static void FAST_FUNC echo_stream(int, servtab_t *);
256static void FAST_FUNC echo_dg(int, servtab_t *);
257#endif
258/* Internet /dev/null */
259#if ENABLE_FEATURE_INETD_SUPPORT_BUILTIN_DISCARD
260static void FAST_FUNC discard_stream(int, servtab_t *);
261static void FAST_FUNC discard_dg(int, servtab_t *);
262#endif
263/* Return 32 bit time since 1900 */
264#if ENABLE_FEATURE_INETD_SUPPORT_BUILTIN_TIME
265static void FAST_FUNC machtime_stream(int, servtab_t *);
266static void FAST_FUNC machtime_dg(int, servtab_t *);
267#endif
268/* Return human-readable time */
269#if ENABLE_FEATURE_INETD_SUPPORT_BUILTIN_DAYTIME
270static void FAST_FUNC daytime_stream(int, servtab_t *);
271static void FAST_FUNC daytime_dg(int, servtab_t *);
272#endif
273/* Familiar character generator */
274#if ENABLE_FEATURE_INETD_SUPPORT_BUILTIN_CHARGEN
275static void FAST_FUNC chargen_stream(int, servtab_t *);
276static void FAST_FUNC chargen_dg(int, servtab_t *);
277#endif
278
279struct builtin {
280    /* NB: not necessarily NUL terminated */
281    char bi_service7[7];      /* internally provided service name */
282    uint8_t bi_fork;          /* 1 if stream fn should run in child */
283    void (*bi_stream_fn)(int, servtab_t *) FAST_FUNC;
284    void (*bi_dgram_fn)(int, servtab_t *) FAST_FUNC;
285};
286
287static const struct builtin builtins[] = {
288#if ENABLE_FEATURE_INETD_SUPPORT_BUILTIN_ECHO
289    { "echo", 1, echo_stream, echo_dg },
290#endif
291#if ENABLE_FEATURE_INETD_SUPPORT_BUILTIN_DISCARD
292    { "discard", 1, discard_stream, discard_dg },
293#endif
294#if ENABLE_FEATURE_INETD_SUPPORT_BUILTIN_CHARGEN
295    { "chargen", 1, chargen_stream, chargen_dg },
296#endif
297#if ENABLE_FEATURE_INETD_SUPPORT_BUILTIN_TIME
298    { "time", 0, machtime_stream, machtime_dg },
299#endif
300#if ENABLE_FEATURE_INETD_SUPPORT_BUILTIN_DAYTIME
301    { "daytime", 0, daytime_stream, daytime_dg },
302#endif
303};
304#endif /* INETD_BUILTINS_ENABLED */
305
306struct globals {
307    rlim_t rlim_ofile_cur;
308    struct rlimit rlim_ofile;
309    servtab_t *serv_list;
310    int global_queuelen;
311    int maxsock;         /* max fd# in allsock, -1: unknown */
312    /* whenever maxsock grows, prev_maxsock is set to new maxsock,
313     * but if maxsock is set to -1, prev_maxsock is not changed */
314    int prev_maxsock;
315    unsigned max_concurrency;
316    smallint alarm_armed;
317    uid_t real_uid; /* user ID who ran us */
318    const char *config_filename;
319    parser_t *parser;
320    char *default_local_hostname;
321#if ENABLE_FEATURE_INETD_SUPPORT_BUILTIN_CHARGEN
322    char *end_ring;
323    char *ring_pos;
324    char ring[128];
325#endif
326    fd_set allsock;
327    /* Used in next_line(), and as scratch read buffer */
328    char line[256];          /* _at least_ 256, see LINE_SIZE */
329} FIX_ALIASING;
330#define G (*(struct globals*)&bb_common_bufsiz1)
331enum { LINE_SIZE = COMMON_BUFSIZE - offsetof(struct globals, line) };
332struct BUG_G_too_big {
333    char BUG_G_too_big[sizeof(G) <= COMMON_BUFSIZE ? 1 : -1];
334};
335#define rlim_ofile_cur  (G.rlim_ofile_cur )
336#define rlim_ofile      (G.rlim_ofile     )
337#define serv_list       (G.serv_list      )
338#define global_queuelen (G.global_queuelen)
339#define maxsock         (G.maxsock        )
340#define prev_maxsock    (G.prev_maxsock   )
341#define max_concurrency (G.max_concurrency)
342#define alarm_armed     (G.alarm_armed    )
343#define real_uid        (G.real_uid       )
344#define config_filename (G.config_filename)
345#define parser          (G.parser         )
346#define default_local_hostname (G.default_local_hostname)
347#define first_ps_byte   (G.first_ps_byte  )
348#define last_ps_byte    (G.last_ps_byte   )
349#define end_ring        (G.end_ring       )
350#define ring_pos        (G.ring_pos       )
351#define ring            (G.ring           )
352#define allsock         (G.allsock        )
353#define line            (G.line           )
354#define INIT_G() do { \
355    rlim_ofile_cur = OPEN_MAX; \
356    global_queuelen = 128; \
357    config_filename = "/etc/inetd.conf"; \
358} while (0)
359
360#if 1
361# define dbg(...) ((void)0)
362#else
363# define dbg(...) \
364do { \
365    int dbg_fd = open("inetd_debug.log", O_WRONLY | O_CREAT | O_APPEND, 0666); \
366    if (dbg_fd >= 0) { \
367        fdprintf(dbg_fd, "%d: ", getpid()); \
368        fdprintf(dbg_fd, __VA_ARGS__); \
369        close(dbg_fd); \
370    } \
371} while (0)
372#endif
373
374static void maybe_close(int fd)
375{
376    if (fd >= 0) {
377        close(fd);
378        dbg("closed fd:%d\n", fd);
379    }
380}
381
382// TODO: move to libbb?
383static len_and_sockaddr *xzalloc_lsa(int family)
384{
385    len_and_sockaddr *lsa;
386    int sz;
387
388    sz = sizeof(struct sockaddr_in);
389    if (family == AF_UNIX)
390        sz = sizeof(struct sockaddr_un);
391#if ENABLE_FEATURE_IPV6
392    if (family == AF_INET6)
393        sz = sizeof(struct sockaddr_in6);
394#endif
395    lsa = xzalloc(LSA_LEN_SIZE + sz);
396    lsa->len = sz;
397    lsa->u.sa.sa_family = family;
398    return lsa;
399}
400
401static void rearm_alarm(void)
402{
403    if (!alarm_armed) {
404        alarm_armed = 1;
405        alarm(RETRYTIME);
406    }
407}
408
409static void block_CHLD_HUP_ALRM(sigset_t *m)
410{
411    sigemptyset(m);
412    sigaddset(m, SIGCHLD);
413    sigaddset(m, SIGHUP);
414    sigaddset(m, SIGALRM);
415    sigprocmask(SIG_BLOCK, m, m); /* old sigmask is stored in m */
416}
417
418static void restore_sigmask(sigset_t *m)
419{
420    sigprocmask(SIG_SETMASK, m, NULL);
421}
422
423#if ENABLE_FEATURE_INETD_RPC
424static void register_rpc(servtab_t *sep)
425{
426    int n;
427    struct sockaddr_in ir_sin;
428    socklen_t size;
429
430    size = sizeof(ir_sin);
431    if (getsockname(sep->se_fd, (struct sockaddr *) &ir_sin, &size) < 0) {
432        bb_perror_msg("getsockname");
433        return;
434    }
435
436    for (n = sep->se_rpcver_lo; n <= sep->se_rpcver_hi; n++) {
437        pmap_unset(sep->se_rpcprog, n);
438        if (!pmap_set(sep->se_rpcprog, n, sep->se_proto_no, ntohs(ir_sin.sin_port)))
439            bb_perror_msg("%s %s: pmap_set(%u,%u,%u,%u)",
440                sep->se_service, sep->se_proto,
441                sep->se_rpcprog, n, sep->se_proto_no, ntohs(ir_sin.sin_port));
442    }
443}
444
445static void unregister_rpc(servtab_t *sep)
446{
447    int n;
448
449    for (n = sep->se_rpcver_lo; n <= sep->se_rpcver_hi; n++) {
450        if (!pmap_unset(sep->se_rpcprog, n))
451            bb_perror_msg("pmap_unset(%u,%u)", sep->se_rpcprog, n);
452    }
453}
454#endif /* FEATURE_INETD_RPC */
455
456static void bump_nofile(void)
457{
458    enum { FD_CHUNK = 32 };
459    struct rlimit rl;
460
461    /* Never fails under Linux (except if you pass it bad arguments) */
462    getrlimit(RLIMIT_NOFILE, &rl);
463    rl.rlim_cur = MIN(rl.rlim_max, rl.rlim_cur + FD_CHUNK);
464    rl.rlim_cur = MIN(FD_SETSIZE, rl.rlim_cur + FD_CHUNK);
465    if (rl.rlim_cur <= rlim_ofile_cur) {
466        bb_error_msg("can't extend file limit, max = %d",
467                        (int) rl.rlim_cur);
468        return;
469    }
470
471    if (setrlimit(RLIMIT_NOFILE, &rl) < 0) {
472        bb_perror_msg("setrlimit");
473        return;
474    }
475
476    rlim_ofile_cur = rl.rlim_cur;
477}
478
479static void remove_fd_from_set(int fd)
480{
481    if (fd >= 0) {
482        FD_CLR(fd, &allsock);
483        dbg("stopped listening on fd:%d\n", fd);
484        maxsock = -1;
485        dbg("maxsock:%d\n", maxsock);
486    }
487}
488
489static void add_fd_to_set(int fd)
490{
491    if (fd >= 0) {
492        FD_SET(fd, &allsock);
493        dbg("started listening on fd:%d\n", fd);
494        if (maxsock >= 0 && fd > maxsock) {
495            prev_maxsock = maxsock = fd;
496            dbg("maxsock:%d\n", maxsock);
497            if ((rlim_t)fd > rlim_ofile_cur - FD_MARGIN)
498                bump_nofile();
499        }
500    }
501}
502
503static void recalculate_maxsock(void)
504{
505    int fd = 0;
506
507    /* We may have no services, in this case maxsock should still be >= 0
508     * (code elsewhere is not happy with maxsock == -1) */
509    maxsock = 0;
510    while (fd <= prev_maxsock) {
511        if (FD_ISSET(fd, &allsock))
512            maxsock = fd;
513        fd++;
514    }
515    dbg("recalculated maxsock:%d\n", maxsock);
516    prev_maxsock = maxsock;
517    if ((rlim_t)maxsock > rlim_ofile_cur - FD_MARGIN)
518        bump_nofile();
519}
520
521static void prepare_socket_fd(servtab_t *sep)
522{
523    int r, fd;
524
525    fd = socket(sep->se_family, sep->se_socktype, 0);
526    if (fd < 0) {
527        bb_perror_msg("socket");
528        return;
529    }
530    setsockopt_reuseaddr(fd);
531
532#if ENABLE_FEATURE_INETD_RPC
533    if (is_rpc_service(sep)) {
534        struct passwd *pwd;
535
536        /* zero out the port for all RPC services; let bind()
537         * find one. */
538        set_nport(&sep->se_lsa->u.sa, 0);
539
540        /* for RPC services, attempt to use a reserved port
541         * if they are going to be running as root. */
542        if (real_uid == 0 && sep->se_family == AF_INET
543         && (pwd = getpwnam(sep->se_user)) != NULL
544         && pwd->pw_uid == 0
545        ) {
546            r = bindresvport(fd, &sep->se_lsa->u.sin);
547        } else {
548            r = bind(fd, &sep->se_lsa->u.sa, sep->se_lsa->len);
549        }
550        if (r == 0) {
551            int saveerrno = errno;
552            /* update lsa with port# */
553            getsockname(fd, &sep->se_lsa->u.sa, &sep->se_lsa->len);
554            errno = saveerrno;
555        }
556    } else
557#endif
558    {
559        if (sep->se_family == AF_UNIX) {
560            struct sockaddr_un *sun;
561            sun = (struct sockaddr_un*)&(sep->se_lsa->u.sa);
562            unlink(sun->sun_path);
563        }
564        r = bind(fd, &sep->se_lsa->u.sa, sep->se_lsa->len);
565    }
566    if (r < 0) {
567        bb_perror_msg("%s/%s: bind",
568                sep->se_service, sep->se_proto);
569        close(fd);
570        rearm_alarm();
571        return;
572    }
573
574    if (sep->se_socktype == SOCK_STREAM) {
575        listen(fd, global_queuelen);
576        dbg("new sep->se_fd:%d (stream)\n", fd);
577    } else {
578        dbg("new sep->se_fd:%d (!stream)\n", fd);
579    }
580
581    add_fd_to_set(fd);
582    sep->se_fd = fd;
583}
584
585static int reopen_config_file(void)
586{
587    free(default_local_hostname);
588    default_local_hostname = xstrdup("*");
589    if (parser != NULL)
590        config_close(parser);
591    parser = config_open(config_filename);
592    return (parser != NULL);
593}
594
595static void close_config_file(void)
596{
597    if (parser) {
598        config_close(parser);
599        parser = NULL;
600    }
601}
602
603static void free_servtab_strings(servtab_t *cp)
604{
605    int i;
606
607    free(cp->se_local_hostname);
608    free(cp->se_service);
609    free(cp->se_proto);
610    free(cp->se_user);
611    free(cp->se_group);
612    free(cp->se_lsa); /* not a string in fact */
613    free(cp->se_program);
614    for (i = 0; i < MAXARGV; i++)
615        free(cp->se_argv[i]);
616}
617
618static servtab_t *new_servtab(void)
619{
620    servtab_t *newtab = xzalloc(sizeof(servtab_t));
621    newtab->se_fd = -1; /* paranoia */
622    return newtab;
623}
624
625static servtab_t *dup_servtab(servtab_t *sep)
626{
627    servtab_t *newtab;
628    int argc;
629
630    newtab = new_servtab();
631    *newtab = *sep; /* struct copy */
632    /* deep-copying strings */
633    newtab->se_service = xstrdup(newtab->se_service);
634    newtab->se_proto = xstrdup(newtab->se_proto);
635    newtab->se_user = xstrdup(newtab->se_user);
636    newtab->se_group = xstrdup(newtab->se_group);
637    newtab->se_program = xstrdup(newtab->se_program);
638    for (argc = 0; argc <= MAXARGV; argc++)
639        newtab->se_argv[argc] = xstrdup(newtab->se_argv[argc]);
640    /* NB: se_fd, se_hostaddr and se_next are always
641     * overwrittend by callers, so we don't bother resetting them
642     * to NULL/0/-1 etc */
643
644    return newtab;
645}
646
647/* gcc generates much more code if this is inlined */
648static servtab_t *parse_one_line(void)
649{
650    int argc;
651    char *token[6+MAXARGV];
652    char *p, *arg;
653    char *hostdelim;
654    servtab_t *sep;
655    servtab_t *nsep;
656 new:
657    sep = new_servtab();
658 more:
659    argc = config_read(parser, token, 6+MAXARGV, 1, "# \t", PARSE_NORMAL);
660    if (!argc) {
661        free(sep);
662        return NULL;
663    }
664
665    /* [host:]service socktype proto wait user[:group] prog [args] */
666    /* Check for "host:...." line */
667    arg = token[0];
668    hostdelim = strrchr(arg, ':');
669    if (hostdelim) {
670        *hostdelim = '\0';
671        sep->se_local_hostname = xstrdup(arg);
672        arg = hostdelim + 1;
673        if (*arg == '\0' && argc == 1) {
674            /* Line has just "host:", change the
675             * default host for the following lines. */
676            free(default_local_hostname);
677            default_local_hostname = sep->se_local_hostname;
678            goto more;
679        }
680    } else
681        sep->se_local_hostname = xstrdup(default_local_hostname);
682
683    /* service socktype proto wait user[:group] prog [args] */
684    sep->se_service = xstrdup(arg);
685
686    /* socktype proto wait user[:group] prog [args] */
687    if (argc < 6) {
688 parse_err:
689        bb_error_msg("parse error on line %u, line is ignored",
690                parser->lineno);
691        free_servtab_strings(sep);
692        /* Just "goto more" can make sep to carry over e.g.
693         * "rpc"-ness (by having se_rpcver_lo != 0).
694         * We will be more paranoid: */
695        free(sep);
696        goto new;
697    }
698
699    {
700        static const int8_t SOCK_xxx[] ALIGN1 = {
701            -1,
702            SOCK_STREAM, SOCK_DGRAM, SOCK_RDM,
703            SOCK_SEQPACKET, SOCK_RAW
704        };
705        sep->se_socktype = SOCK_xxx[1 + index_in_strings(
706            "stream""\0" "dgram""\0" "rdm""\0"
707            "seqpacket""\0" "raw""\0"
708            , token[1])];
709    }
710
711    /* {unix,[rpc/]{tcp,udp}[6]} wait user[:group] prog [args] */
712    sep->se_proto = arg = xstrdup(token[2]);
713    if (strcmp(arg, "unix") == 0) {
714        sep->se_family = AF_UNIX;
715    } else {
716        char *six;
717        sep->se_family = AF_INET;
718        six = last_char_is(arg, '6');
719        if (six) {
720#if ENABLE_FEATURE_IPV6
721            *six = '\0';
722            sep->se_family = AF_INET6;
723#else
724            bb_error_msg("%s: no support for IPv6", sep->se_proto);
725            goto parse_err;
726#endif
727        }
728        if (strncmp(arg, "rpc/", 4) == 0) {
729#if ENABLE_FEATURE_INETD_RPC
730            unsigned n;
731            arg += 4;
732            p = strchr(sep->se_service, '/');
733            if (p == NULL) {
734                bb_error_msg("no rpc version: '%s'", sep->se_service);
735                goto parse_err;
736            }
737            *p++ = '\0';
738            n = bb_strtou(p, &p, 10);
739            if (n > INT_MAX) {
740 bad_ver_spec:
741                bb_error_msg("bad rpc version");
742                goto parse_err;
743            }
744            sep->se_rpcver_lo = sep->se_rpcver_hi = n;
745            if (*p == '-') {
746                p++;
747                n = bb_strtou(p, &p, 10);
748                if (n > INT_MAX || (int)n < sep->se_rpcver_lo)
749                    goto bad_ver_spec;
750                sep->se_rpcver_hi = n;
751            }
752            if (*p != '\0')
753                goto bad_ver_spec;
754#else
755            bb_error_msg("no support for rpc services");
756            goto parse_err;
757#endif
758        }
759        /* we don't really need getprotobyname()! */
760        if (strcmp(arg, "tcp") == 0)
761            sep->se_proto_no = IPPROTO_TCP; /* = 6 */
762        if (strcmp(arg, "udp") == 0)
763            sep->se_proto_no = IPPROTO_UDP; /* = 17 */
764        if (six)
765            *six = '6';
766        if (!sep->se_proto_no) /* not tcp/udp?? */
767            goto parse_err;
768    }
769
770    /* [no]wait[.max] user[:group] prog [args] */
771    arg = token[3];
772    sep->se_max = max_concurrency;
773    p = strchr(arg, '.');
774    if (p) {
775        *p++ = '\0';
776        sep->se_max = bb_strtou(p, NULL, 10);
777        if (errno)
778            goto parse_err;
779    }
780    sep->se_wait = (arg[0] != 'n' || arg[1] != 'o');
781    if (!sep->se_wait) /* "no" seen */
782        arg += 2;
783    if (strcmp(arg, "wait") != 0)
784        goto parse_err;
785
786    /* user[:group] prog [args] */
787    sep->se_user = xstrdup(token[4]);
788    arg = strchr(sep->se_user, '.');
789    if (arg == NULL)
790        arg = strchr(sep->se_user, ':');
791    if (arg) {
792        *arg++ = '\0';
793        sep->se_group = xstrdup(arg);
794    }
795
796    /* prog [args] */
797    sep->se_program = xstrdup(token[5]);
798#ifdef INETD_BUILTINS_ENABLED
799    if (strcmp(sep->se_program, "internal") == 0
800     && strlen(sep->se_service) <= 7
801     && (sep->se_socktype == SOCK_STREAM
802         || sep->se_socktype == SOCK_DGRAM)
803    ) {
804        unsigned i;
805        for (i = 0; i < ARRAY_SIZE(builtins); i++)
806            if (strncmp(builtins[i].bi_service7, sep->se_service, 7) == 0)
807                goto found_bi;
808        bb_error_msg("unknown internal service %s", sep->se_service);
809        goto parse_err;
810 found_bi:
811        sep->se_builtin = &builtins[i];
812        /* stream builtins must be "nowait", dgram must be "wait" */
813        if (sep->se_wait != (sep->se_socktype == SOCK_DGRAM))
814            goto parse_err;
815    }
816#endif
817    argc = 0;
818    while ((arg = token[6+argc]) != NULL && argc < MAXARGV)
819        sep->se_argv[argc++] = xstrdup(arg);
820    /* Some inetd.conf files have no argv's, not even argv[0].
821     * Fix them up.
822     * (Technically, programs can be execed with argv[0] = NULL,
823     * but many programs do not like that at all) */
824    if (argc == 0)
825        sep->se_argv[0] = xstrdup(sep->se_program);
826
827    /* catch mixups. "<service> stream udp ..." == wtf */
828    if (sep->se_socktype == SOCK_STREAM) {
829        if (sep->se_proto_no == IPPROTO_UDP)
830            goto parse_err;
831    }
832    if (sep->se_socktype == SOCK_DGRAM) {
833        if (sep->se_proto_no == IPPROTO_TCP)
834            goto parse_err;
835    }
836
837//  bb_info_msg(
838//      "ENTRY[%s][%s][%s][%d][%d][%d][%d][%d][%s][%s][%s]",
839//      sep->se_local_hostname, sep->se_service, sep->se_proto, sep->se_wait, sep->se_proto_no,
840//      sep->se_max, sep->se_count, sep->se_time, sep->se_user, sep->se_group, sep->se_program);
841
842    /* check if the hostname specifier is a comma separated list
843     * of hostnames. we'll make new entries for each address. */
844    while ((hostdelim = strrchr(sep->se_local_hostname, ',')) != NULL) {
845        nsep = dup_servtab(sep);
846        /* NUL terminate the hostname field of the existing entry,
847         * and make a dup for the new entry. */
848        *hostdelim++ = '\0';
849        nsep->se_local_hostname = xstrdup(hostdelim);
850        nsep->se_next = sep->se_next;
851        sep->se_next = nsep;
852    }
853
854    /* was doing it here: */
855    /* DNS resolution, create copies for each IP address */
856    /* IPv6-ization destroyed it :( */
857
858    return sep;
859}
860
861static servtab_t *insert_in_servlist(servtab_t *cp)
862{
863    servtab_t *sep;
864    sigset_t omask;
865
866    sep = new_servtab();
867    *sep = *cp; /* struct copy */
868    sep->se_fd = -1;
869#if ENABLE_FEATURE_INETD_RPC
870    sep->se_rpcprog = -1;
871#endif
872    block_CHLD_HUP_ALRM(&omask);
873    sep->se_next = serv_list;
874    serv_list = sep;
875    restore_sigmask(&omask);
876    return sep;
877}
878
879static int same_serv_addr_proto(servtab_t *old, servtab_t *new)
880{
881    if (strcmp(old->se_local_hostname, new->se_local_hostname) != 0)
882        return 0;
883    if (strcmp(old->se_service, new->se_service) != 0)
884        return 0;
885    if (strcmp(old->se_proto, new->se_proto) != 0)
886        return 0;
887    return 1;
888}
889
890static void reread_config_file(int sig UNUSED_PARAM)
891{
892    servtab_t *sep, *cp, **sepp;
893    len_and_sockaddr *lsa;
894    sigset_t omask;
895    unsigned n;
896    uint16_t port;
897    int save_errno = errno;
898
899    if (!reopen_config_file())
900        goto ret;
901    for (sep = serv_list; sep; sep = sep->se_next)
902        sep->se_checked = 0;
903
904    goto first_line;
905    while (1) {
906        if (cp == NULL) {
907 first_line:
908            cp = parse_one_line();
909            if (cp == NULL)
910                break;
911        }
912        for (sep = serv_list; sep; sep = sep->se_next)
913            if (same_serv_addr_proto(sep, cp))
914                goto equal_servtab;
915        /* not an "equal" servtab */
916        sep = insert_in_servlist(cp);
917        goto after_check;
918 equal_servtab:
919        {
920            int i;
921
922            block_CHLD_HUP_ALRM(&omask);
923#if ENABLE_FEATURE_INETD_RPC
924            if (is_rpc_service(sep))
925                unregister_rpc(sep);
926            sep->se_rpcver_lo = cp->se_rpcver_lo;
927            sep->se_rpcver_hi = cp->se_rpcver_hi;
928#endif
929            if (cp->se_wait == 0) {
930                /* New config says "nowait". If old one
931                 * was "wait", we currently may be waiting
932                 * for a child (and not accepting connects).
933                 * Stop waiting, start listening again.
934                 * (if it's not true, this op is harmless) */
935                add_fd_to_set(sep->se_fd);
936            }
937            sep->se_wait = cp->se_wait;
938            sep->se_max = cp->se_max;
939            /* string fields need more love - we don't want to leak them */
940#define SWAP(type, a, b) do { type c = (type)a; a = (type)b; b = (type)c; } while (0)
941            SWAP(char*, sep->se_user, cp->se_user);
942            SWAP(char*, sep->se_group, cp->se_group);
943            SWAP(char*, sep->se_program, cp->se_program);
944            for (i = 0; i < MAXARGV; i++)
945                SWAP(char*, sep->se_argv[i], cp->se_argv[i]);
946#undef SWAP
947            restore_sigmask(&omask);
948            free_servtab_strings(cp);
949        }
950 after_check:
951        /* cp->string_fields are consumed by insert_in_servlist()
952         * or freed at this point, cp itself is not yet freed. */
953        sep->se_checked = 1;
954
955        /* create new len_and_sockaddr */
956        switch (sep->se_family) {
957            struct sockaddr_un *sun;
958        case AF_UNIX:
959            lsa = xzalloc_lsa(AF_UNIX);
960            sun = (struct sockaddr_un*)&lsa->u.sa;
961            safe_strncpy(sun->sun_path, sep->se_service, sizeof(sun->sun_path));
962            break;
963
964        default: /* case AF_INET, case AF_INET6 */
965            n = bb_strtou(sep->se_service, NULL, 10);
966#if ENABLE_FEATURE_INETD_RPC
967            if (is_rpc_service(sep)) {
968                sep->se_rpcprog = n;
969                if (errno) { /* se_service is not numeric */
970                    struct rpcent *rp = getrpcbyname(sep->se_service);
971                    if (rp == NULL) {
972                        bb_error_msg("%s: unknown rpc service", sep->se_service);
973                        goto next_cp;
974                    }
975                    sep->se_rpcprog = rp->r_number;
976                }
977                if (sep->se_fd == -1)
978                    prepare_socket_fd(sep);
979                if (sep->se_fd != -1)
980                    register_rpc(sep);
981                goto next_cp;
982            }
983#endif
984            /* what port to listen on? */
985            port = htons(n);
986            if (errno || n > 0xffff) { /* se_service is not numeric */
987                char protoname[4];
988                struct servent *sp;
989                /* can result only in "tcp" or "udp": */
990                safe_strncpy(protoname, sep->se_proto, 4);
991                sp = getservbyname(sep->se_service, protoname);
992                if (sp == NULL) {
993                    bb_error_msg("%s/%s: unknown service",
994                            sep->se_service, sep->se_proto);
995                    goto next_cp;
996                }
997                port = sp->s_port;
998            }
999            if (LONE_CHAR(sep->se_local_hostname, '*')) {
1000                lsa = xzalloc_lsa(sep->se_family);
1001                set_nport(&lsa->u.sa, port);
1002            } else {
1003                lsa = host_and_af2sockaddr(sep->se_local_hostname,
1004                        ntohs(port), sep->se_family);
1005                if (!lsa) {
1006                    bb_error_msg("%s/%s: unknown host '%s'",
1007                        sep->se_service, sep->se_proto,
1008                        sep->se_local_hostname);
1009                    goto next_cp;
1010                }
1011            }
1012            break;
1013        } /* end of "switch (sep->se_family)" */
1014
1015        /* did lsa change? Then close/open */
1016        if (sep->se_lsa == NULL
1017         || lsa->len != sep->se_lsa->len
1018         || memcmp(&lsa->u.sa, &sep->se_lsa->u.sa, lsa->len) != 0
1019        ) {
1020            remove_fd_from_set(sep->se_fd);
1021            maybe_close(sep->se_fd);
1022            free(sep->se_lsa);
1023            sep->se_lsa = lsa;
1024            sep->se_fd = -1;
1025        } else {
1026            free(lsa);
1027        }
1028        if (sep->se_fd == -1)
1029            prepare_socket_fd(sep);
1030 next_cp:
1031        sep = cp->se_next;
1032        free(cp);
1033        cp = sep;
1034    } /* end of "while (1) parse lines" */
1035    close_config_file();
1036
1037    /* Purge anything not looked at above - these are stale entries,
1038     * new config file doesnt have them. */
1039    block_CHLD_HUP_ALRM(&omask);
1040    sepp = &serv_list;
1041    while ((sep = *sepp) != NULL) {
1042        if (sep->se_checked) {
1043            sepp = &sep->se_next;
1044            continue;
1045        }
1046        *sepp = sep->se_next;
1047        remove_fd_from_set(sep->se_fd);
1048        maybe_close(sep->se_fd);
1049#if ENABLE_FEATURE_INETD_RPC
1050        if (is_rpc_service(sep))
1051            unregister_rpc(sep);
1052#endif
1053        if (sep->se_family == AF_UNIX)
1054            unlink(sep->se_service);
1055        free_servtab_strings(sep);
1056        free(sep);
1057    }
1058    restore_sigmask(&omask);
1059 ret:
1060    errno = save_errno;
1061}
1062
1063static void reap_child(int sig UNUSED_PARAM)
1064{
1065    pid_t pid;
1066    int status;
1067    servtab_t *sep;
1068    int save_errno = errno;
1069
1070    for (;;) {
1071        pid = wait_any_nohang(&status);
1072        if (pid <= 0)
1073            break;
1074        for (sep = serv_list; sep; sep = sep->se_next) {
1075            if (sep->se_wait != pid)
1076                continue;
1077            /* One of our "wait" services */
1078            if (WIFEXITED(status) && WEXITSTATUS(status))
1079                bb_error_msg("%s: exit status %u",
1080                        sep->se_program, WEXITSTATUS(status));
1081            else if (WIFSIGNALED(status))
1082                bb_error_msg("%s: exit signal %u",
1083                        sep->se_program, WTERMSIG(status));
1084            sep->se_wait = 1;
1085            add_fd_to_set(sep->se_fd);
1086            break;
1087        }
1088    }
1089    errno = save_errno;
1090}
1091
1092static void retry_network_setup(int sig UNUSED_PARAM)
1093{
1094    int save_errno = errno;
1095    servtab_t *sep;
1096
1097    alarm_armed = 0;
1098    for (sep = serv_list; sep; sep = sep->se_next) {
1099        if (sep->se_fd == -1) {
1100            prepare_socket_fd(sep);
1101#if ENABLE_FEATURE_INETD_RPC
1102            if (sep->se_fd != -1 && is_rpc_service(sep))
1103                register_rpc(sep);
1104#endif
1105        }
1106    }
1107    errno = save_errno;
1108}
1109
1110static void clean_up_and_exit(int sig UNUSED_PARAM)
1111{
1112    servtab_t *sep;
1113
1114    /* XXX signal race walking sep list */
1115    for (sep = serv_list; sep; sep = sep->se_next) {
1116        if (sep->se_fd == -1)
1117            continue;
1118
1119        switch (sep->se_family) {
1120        case AF_UNIX:
1121            unlink(sep->se_service);
1122            break;
1123        default: /* case AF_INET, AF_INET6 */
1124#if ENABLE_FEATURE_INETD_RPC
1125            if (sep->se_wait == 1 && is_rpc_service(sep))
1126                unregister_rpc(sep);   /* XXX signal race */
1127#endif
1128            break;
1129        }
1130        if (ENABLE_FEATURE_CLEAN_UP)
1131            close(sep->se_fd);
1132    }
1133    remove_pidfile(CONFIG_PID_FILE_PATH "/inetd.pid");
1134    exit(EXIT_SUCCESS);
1135}
1136
1137int inetd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
1138int inetd_main(int argc UNUSED_PARAM, char **argv)
1139{
1140    struct sigaction sa, saved_pipe_handler;
1141    servtab_t *sep, *sep2;
1142    struct passwd *pwd;
1143    struct group *grp = grp; /* for compiler */
1144    int opt;
1145    pid_t pid;
1146    sigset_t omask;
1147
1148    INIT_G();
1149
1150    real_uid = getuid();
1151    if (real_uid != 0) /* run by non-root user */
1152        config_filename = NULL;
1153
1154    opt_complementary = "R+:q+"; /* -q N, -R N */
1155    opt = getopt32(argv, "R:feq:", &max_concurrency, &global_queuelen);
1156    argv += optind;
1157    //argc -= optind;
1158    if (argv[0])
1159        config_filename = argv[0];
1160    if (config_filename == NULL)
1161        bb_error_msg_and_die("non-root must specify config file");
1162    if (!(opt & 2))
1163        bb_daemonize_or_rexec(0, argv - optind);
1164    else
1165        bb_sanitize_stdio();
1166    if (!(opt & 4)) {
1167        /* LOG_NDELAY: connect to syslog daemon NOW.
1168         * Otherwise, we may open syslog socket
1169         * in vforked child, making opened fds and syslog()
1170         * internal state inconsistent.
1171         * This was observed to leak file descriptors. */
1172        openlog(applet_name, LOG_PID | LOG_NDELAY, LOG_DAEMON);
1173        logmode = LOGMODE_SYSLOG;
1174    }
1175
1176    if (real_uid == 0) {
1177        /* run by root, ensure groups vector gets trashed */
1178        gid_t gid = getgid();
1179        setgroups(1, &gid);
1180    }
1181
1182    write_pidfile(CONFIG_PID_FILE_PATH "/inetd.pid");
1183
1184    /* never fails under Linux (except if you pass it bad arguments) */
1185    getrlimit(RLIMIT_NOFILE, &rlim_ofile);
1186    rlim_ofile_cur = rlim_ofile.rlim_cur;
1187    if (rlim_ofile_cur == RLIM_INFINITY)    /* ! */
1188        rlim_ofile_cur = OPEN_MAX;
1189
1190    memset(&sa, 0, sizeof(sa));
1191    /*sigemptyset(&sa.sa_mask); - memset did it */
1192    sigaddset(&sa.sa_mask, SIGALRM);
1193    sigaddset(&sa.sa_mask, SIGCHLD);
1194    sigaddset(&sa.sa_mask, SIGHUP);
1195//FIXME: explain why no SA_RESTART
1196//FIXME: retry_network_setup is unsafe to run in signal handler (many reasons)!
1197    sa.sa_handler = retry_network_setup;
1198    sigaction_set(SIGALRM, &sa);
1199//FIXME: reread_config_file is unsafe to run in signal handler(many reasons)!
1200    sa.sa_handler = reread_config_file;
1201    sigaction_set(SIGHUP, &sa);
1202//FIXME: reap_child is unsafe to run in signal handler (uses stdio)!
1203    sa.sa_handler = reap_child;
1204    sigaction_set(SIGCHLD, &sa);
1205//FIXME: clean_up_and_exit is unsafe to run in signal handler (uses stdio)!
1206    sa.sa_handler = clean_up_and_exit;
1207    sigaction_set(SIGTERM, &sa);
1208    sa.sa_handler = clean_up_and_exit;
1209    sigaction_set(SIGINT, &sa);
1210    sa.sa_handler = SIG_IGN;
1211    sigaction(SIGPIPE, &sa, &saved_pipe_handler);
1212
1213    reread_config_file(SIGHUP); /* load config from file */
1214
1215    for (;;) {
1216        int ready_fd_cnt;
1217        int ctrl, accepted_fd, new_udp_fd;
1218        fd_set readable;
1219
1220        if (maxsock < 0)
1221            recalculate_maxsock();
1222
1223        readable = allsock; /* struct copy */
1224        /* if there are no fds to wait on, we will block
1225         * until signal wakes us up (maxsock == 0, but readable
1226         * never contains fds 0 and 1...) */
1227        ready_fd_cnt = select(maxsock + 1, &readable, NULL, NULL, NULL);
1228        if (ready_fd_cnt < 0) {
1229            if (errno != EINTR) {
1230                bb_perror_msg("select");
1231                sleep(1);
1232            }
1233            continue;
1234        }
1235        dbg("ready_fd_cnt:%d\n", ready_fd_cnt);
1236
1237        for (sep = serv_list; ready_fd_cnt && sep; sep = sep->se_next) {
1238            if (sep->se_fd == -1 || !FD_ISSET(sep->se_fd, &readable))
1239                continue;
1240
1241            dbg("ready fd:%d\n", sep->se_fd);
1242            ready_fd_cnt--;
1243            ctrl = sep->se_fd;
1244            accepted_fd = -1;
1245            new_udp_fd = -1;
1246            if (!sep->se_wait) {
1247                if (sep->se_socktype == SOCK_STREAM) {
1248                    ctrl = accepted_fd = accept(sep->se_fd, NULL, NULL);
1249                    dbg("accepted_fd:%d\n", accepted_fd);
1250                    if (ctrl < 0) {
1251                        if (errno != EINTR)
1252                            bb_perror_msg("accept (for %s)", sep->se_service);
1253                        continue;
1254                    }
1255                }
1256                /* "nowait" udp */
1257                if (sep->se_socktype == SOCK_DGRAM
1258                 && sep->se_family != AF_UNIX
1259                ) {
1260/* How udp "nowait" works:
1261 * child peeks at (received and buffered by kernel) UDP packet,
1262 * performs connect() on the socket so that it is linked only
1263 * to this peer. But this also affects parent, because descriptors
1264 * are shared after fork() a-la dup(). When parent performs
1265 * select(), it will see this descriptor connected to the peer (!)
1266 * and still readable, will act on it and mess things up
1267 * (can create many copies of same child, etc).
1268 * Parent must create and use new socket instead. */
1269                    new_udp_fd = socket(sep->se_family, SOCK_DGRAM, 0);
1270                    dbg("new_udp_fd:%d\n", new_udp_fd);
1271                    if (new_udp_fd < 0) { /* error: eat packet, forget about it */
1272 udp_err:
1273                        recv(sep->se_fd, line, LINE_SIZE, MSG_DONTWAIT);
1274                        continue;
1275                    }
1276                    setsockopt_reuseaddr(new_udp_fd);
1277                    /* TODO: better do bind after fork in parent,
1278                     * so that we don't have two wildcard bound sockets
1279                     * even for a brief moment? */
1280                    if (bind(new_udp_fd, &sep->se_lsa->u.sa, sep->se_lsa->len) < 0) {
1281                        dbg("bind(new_udp_fd) failed\n");
1282                        close(new_udp_fd);
1283                        goto udp_err;
1284                    }
1285                    dbg("bind(new_udp_fd) succeeded\n");
1286                }
1287            }
1288
1289            block_CHLD_HUP_ALRM(&omask);
1290            pid = 0;
1291#ifdef INETD_BUILTINS_ENABLED
1292            /* do we need to fork? */
1293            if (sep->se_builtin == NULL
1294             || (sep->se_socktype == SOCK_STREAM
1295                 && sep->se_builtin->bi_fork))
1296#endif
1297            {
1298                if (sep->se_max != 0) {
1299                    if (++sep->se_count == 1)
1300                        sep->se_time = monotonic_sec();
1301                    else if (sep->se_count >= sep->se_max) {
1302                        unsigned now = monotonic_sec();
1303                        /* did we accumulate se_max connects too quickly? */
1304                        if (now - sep->se_time <= CNT_INTERVAL) {
1305                            bb_error_msg("%s/%s: too many connections, pausing",
1306                                    sep->se_service, sep->se_proto);
1307                            remove_fd_from_set(sep->se_fd);
1308                            close(sep->se_fd);
1309                            sep->se_fd = -1;
1310                            sep->se_count = 0;
1311                            rearm_alarm(); /* will revive it in RETRYTIME sec */
1312                            restore_sigmask(&omask);
1313                            maybe_close(new_udp_fd);
1314                            maybe_close(accepted_fd);
1315                            continue; /* -> check next fd in fd set */
1316                        }
1317                        sep->se_count = 0;
1318                    }
1319                }
1320                /* on NOMMU, streamed chargen
1321                 * builtin wouldn't work, but it is
1322                 * not allowed on NOMMU (ifdefed out) */
1323#ifdef INETD_BUILTINS_ENABLED
1324                if (BB_MMU && sep->se_builtin)
1325                    pid = fork();
1326                else
1327#endif
1328                    pid = vfork();
1329
1330                if (pid < 0) { /* fork error */
1331                    bb_perror_msg("vfork"+1);
1332                    sleep(1);
1333                    restore_sigmask(&omask);
1334                    maybe_close(new_udp_fd);
1335                    maybe_close(accepted_fd);
1336                    continue; /* -> check next fd in fd set */
1337                }
1338                if (pid == 0)
1339                    pid--; /* -1: "we did fork and we are child" */
1340            }
1341            /* if pid == 0 here, we didn't fork */
1342
1343            if (pid > 0) { /* parent */
1344                if (sep->se_wait) {
1345                    /* wait: we passed socket to child,
1346                     * will wait for child to terminate */
1347                    sep->se_wait = pid;
1348                    remove_fd_from_set(sep->se_fd);
1349                }
1350                if (new_udp_fd >= 0) {
1351                    /* udp nowait: child connected the socket,
1352                     * we created and will use new, unconnected one */
1353                    xmove_fd(new_udp_fd, sep->se_fd);
1354                    dbg("moved new_udp_fd:%d to sep->se_fd:%d\n", new_udp_fd, sep->se_fd);
1355                }
1356                restore_sigmask(&omask);
1357                maybe_close(accepted_fd);
1358                continue; /* -> check next fd in fd set */
1359            }
1360
1361            /* we are either child or didn't fork at all */
1362#ifdef INETD_BUILTINS_ENABLED
1363            if (sep->se_builtin) {
1364                if (pid) { /* "pid" is -1: we did fork */
1365                    close(sep->se_fd); /* listening socket */
1366                    dbg("closed sep->se_fd:%d\n", sep->se_fd);
1367                    logmode = LOGMODE_NONE; /* make xwrite etc silent */
1368                }
1369                restore_sigmask(&omask);
1370                if (sep->se_socktype == SOCK_STREAM)
1371                    sep->se_builtin->bi_stream_fn(ctrl, sep);
1372                else
1373                    sep->se_builtin->bi_dgram_fn(ctrl, sep);
1374                if (pid) /* we did fork */
1375                    _exit(EXIT_FAILURE);
1376                maybe_close(accepted_fd);
1377                continue; /* -> check next fd in fd set */
1378            }
1379#endif
1380            /* child */
1381            setsid();
1382            /* "nowait" udp */
1383            if (new_udp_fd >= 0) {
1384                len_and_sockaddr *lsa;
1385                int r;
1386
1387                close(new_udp_fd);
1388                dbg("closed new_udp_fd:%d\n", new_udp_fd);
1389                lsa = xzalloc_lsa(sep->se_family);
1390                /* peek at the packet and remember peer addr */
1391                r = recvfrom(ctrl, NULL, 0, MSG_PEEK|MSG_DONTWAIT,
1392                    &lsa->u.sa, &lsa->len);
1393                if (r < 0)
1394                    goto do_exit1;
1395                /* make this socket "connected" to peer addr:
1396                 * only packets from this peer will be recv'ed,
1397                 * and bare write()/send() will work on it */
1398                connect(ctrl, &lsa->u.sa, lsa->len);
1399                dbg("connected ctrl:%d to remote peer\n", ctrl);
1400                free(lsa);
1401            }
1402            /* prepare env and exec program */
1403            pwd = getpwnam(sep->se_user);
1404            if (pwd == NULL) {
1405                bb_error_msg("%s: no such %s", sep->se_user, "user");
1406                goto do_exit1;
1407            }
1408            if (sep->se_group && (grp = getgrnam(sep->se_group)) == NULL) {
1409                bb_error_msg("%s: no such %s", sep->se_group, "group");
1410                goto do_exit1;
1411            }
1412            if (real_uid != 0 && real_uid != pwd->pw_uid) {
1413                /* a user running private inetd */
1414                bb_error_msg("non-root must run services as himself");
1415                goto do_exit1;
1416            }
1417            if (pwd->pw_uid != 0) {
1418                if (sep->se_group)
1419                    pwd->pw_gid = grp->gr_gid;
1420                /* initgroups, setgid, setuid: */
1421                change_identity(pwd);
1422            } else if (sep->se_group) {
1423                xsetgid(grp->gr_gid);
1424                setgroups(1, &grp->gr_gid);
1425            }
1426            if (rlim_ofile.rlim_cur != rlim_ofile_cur)
1427                if (setrlimit(RLIMIT_NOFILE, &rlim_ofile) < 0)
1428                    bb_perror_msg("setrlimit");
1429
1430            /* closelog(); - WRONG. we are after vfork,
1431             * this may confuse syslog() internal state.
1432             * Let's hope libc sets syslog fd to CLOEXEC...
1433             */
1434            xmove_fd(ctrl, STDIN_FILENO);
1435            xdup2(STDIN_FILENO, STDOUT_FILENO);
1436            dbg("moved ctrl:%d to fd 0,1[,2]\n", ctrl);
1437            /* manpages of inetd I managed to find either say
1438             * that stderr is also redirected to the network,
1439             * or do not talk about redirection at all (!) */
1440            if (!sep->se_wait) /* only for usual "tcp nowait" */
1441                xdup2(STDIN_FILENO, STDERR_FILENO);
1442            /* NB: among others, this loop closes listening sockets
1443             * for nowait stream children */
1444            for (sep2 = serv_list; sep2; sep2 = sep2->se_next)
1445                if (sep2->se_fd != ctrl)
1446                    maybe_close(sep2->se_fd);
1447            sigaction_set(SIGPIPE, &saved_pipe_handler);
1448            restore_sigmask(&omask);
1449            dbg("execing:'%s'\n", sep->se_program);
1450            BB_EXECVP(sep->se_program, sep->se_argv);
1451            bb_perror_msg("can't execute '%s'", sep->se_program);
1452 do_exit1:
1453            /* eat packet in udp case */
1454            if (sep->se_socktype != SOCK_STREAM)
1455                recv(0, line, LINE_SIZE, MSG_DONTWAIT);
1456            _exit(EXIT_FAILURE);
1457        } /* for (sep = servtab...) */
1458    } /* for (;;) */
1459}
1460
1461#if !BB_MMU
1462static const char *const cat_args[] = { "cat", NULL };
1463#endif
1464
1465/*
1466 * Internet services provided internally by inetd:
1467 */
1468#if ENABLE_FEATURE_INETD_SUPPORT_BUILTIN_ECHO
1469/* Echo service -- echo data back. */
1470/* ARGSUSED */
1471static void FAST_FUNC echo_stream(int s, servtab_t *sep UNUSED_PARAM)
1472{
1473#if BB_MMU
1474    while (1) {
1475        ssize_t sz = safe_read(s, line, LINE_SIZE);
1476        if (sz <= 0)
1477            break;
1478        xwrite(s, line, sz);
1479    }
1480#else
1481    /* We are after vfork here! */
1482    /* move network socket to stdin/stdout */
1483    xmove_fd(s, STDIN_FILENO);
1484    xdup2(STDIN_FILENO, STDOUT_FILENO);
1485    /* no error messages please... */
1486    close(STDERR_FILENO);
1487    xopen(bb_dev_null, O_WRONLY);
1488    BB_EXECVP("cat", (char**)cat_args);
1489    /* on failure we return to main, which does exit(EXIT_FAILURE) */
1490#endif
1491}
1492static void FAST_FUNC echo_dg(int s, servtab_t *sep)
1493{
1494    enum { BUFSIZE = 12*1024 }; /* for jumbo sized packets! :) */
1495    char *buf = xmalloc(BUFSIZE); /* too big for stack */
1496    int sz;
1497    len_and_sockaddr *lsa = alloca(LSA_LEN_SIZE + sep->se_lsa->len);
1498
1499    lsa->len = sep->se_lsa->len;
1500    /* dgram builtins are non-forking - DONT BLOCK! */
1501    sz = recvfrom(s, buf, BUFSIZE, MSG_DONTWAIT, &lsa->u.sa, &lsa->len);
1502    if (sz > 0)
1503        sendto(s, buf, sz, 0, &lsa->u.sa, lsa->len);
1504    free(buf);
1505}
1506#endif  /* FEATURE_INETD_SUPPORT_BUILTIN_ECHO */
1507
1508
1509#if ENABLE_FEATURE_INETD_SUPPORT_BUILTIN_DISCARD
1510/* Discard service -- ignore data. */
1511/* ARGSUSED */
1512static void FAST_FUNC discard_stream(int s, servtab_t *sep UNUSED_PARAM)
1513{
1514#if BB_MMU
1515    while (safe_read(s, line, LINE_SIZE) > 0)
1516        continue;
1517#else
1518    /* We are after vfork here! */
1519    /* move network socket to stdin */
1520    xmove_fd(s, STDIN_FILENO);
1521    /* discard output */
1522    close(STDOUT_FILENO);
1523    xopen(bb_dev_null, O_WRONLY);
1524    /* no error messages please... */
1525    xdup2(STDOUT_FILENO, STDERR_FILENO);
1526    BB_EXECVP("cat", (char**)cat_args);
1527    /* on failure we return to main, which does exit(EXIT_FAILURE) */
1528#endif
1529}
1530/* ARGSUSED */
1531static void FAST_FUNC discard_dg(int s, servtab_t *sep UNUSED_PARAM)
1532{
1533    /* dgram builtins are non-forking - DONT BLOCK! */
1534    recv(s, line, LINE_SIZE, MSG_DONTWAIT);
1535}
1536#endif /* FEATURE_INETD_SUPPORT_BUILTIN_DISCARD */
1537
1538
1539#if ENABLE_FEATURE_INETD_SUPPORT_BUILTIN_CHARGEN
1540#define LINESIZ 72
1541static void init_ring(void)
1542{
1543    int i;
1544
1545    end_ring = ring;
1546    for (i = ' '; i < 127; i++)
1547        *end_ring++ = i;
1548}
1549/* Character generator. MMU arches only. */
1550/* ARGSUSED */
1551static void FAST_FUNC chargen_stream(int s, servtab_t *sep UNUSED_PARAM)
1552{
1553    char *rs;
1554    int len;
1555    char text[LINESIZ + 2];
1556
1557    if (!end_ring) {
1558        init_ring();
1559        rs = ring;
1560    }
1561
1562    text[LINESIZ] = '\r';
1563    text[LINESIZ + 1] = '\n';
1564    rs = ring;
1565    for (;;) {
1566        len = end_ring - rs;
1567        if (len >= LINESIZ)
1568            memmove(text, rs, LINESIZ);
1569        else {
1570            memmove(text, rs, len);
1571            memmove(text + len, ring, LINESIZ - len);
1572        }
1573        if (++rs == end_ring)
1574            rs = ring;
1575        xwrite(s, text, sizeof(text));
1576    }
1577}
1578/* ARGSUSED */
1579static void FAST_FUNC chargen_dg(int s, servtab_t *sep)
1580{
1581    int len;
1582    char text[LINESIZ + 2];
1583    len_and_sockaddr *lsa = alloca(LSA_LEN_SIZE + sep->se_lsa->len);
1584
1585    /* Eat UDP packet which started it all */
1586    /* dgram builtins are non-forking - DONT BLOCK! */
1587    lsa->len = sep->se_lsa->len;
1588    if (recvfrom(s, text, sizeof(text), MSG_DONTWAIT, &lsa->u.sa, &lsa->len) < 0)
1589        return;
1590
1591    if (!end_ring) {
1592        init_ring();
1593        ring_pos = ring;
1594    }
1595
1596    len = end_ring - ring_pos;
1597    if (len >= LINESIZ)
1598        memmove(text, ring_pos, LINESIZ);
1599    else {
1600        memmove(text, ring_pos, len);
1601        memmove(text + len, ring, LINESIZ - len);
1602    }
1603    if (++ring_pos == end_ring)
1604        ring_pos = ring;
1605    text[LINESIZ] = '\r';
1606    text[LINESIZ + 1] = '\n';
1607    sendto(s, text, sizeof(text), 0, &lsa->u.sa, lsa->len);
1608}
1609#endif /* FEATURE_INETD_SUPPORT_BUILTIN_CHARGEN */
1610
1611
1612#if ENABLE_FEATURE_INETD_SUPPORT_BUILTIN_TIME
1613/*
1614 * Return a machine readable date and time, in the form of the
1615 * number of seconds since midnight, Jan 1, 1900.  Since gettimeofday
1616 * returns the number of seconds since midnight, Jan 1, 1970,
1617 * we must add 2208988800 seconds to this figure to make up for
1618 * some seventy years Bell Labs was asleep.
1619 */
1620static uint32_t machtime(void)
1621{
1622    struct timeval tv;
1623
1624    gettimeofday(&tv, NULL);
1625    return htonl((uint32_t)(tv.tv_sec + 2208988800));
1626}
1627/* ARGSUSED */
1628static void FAST_FUNC machtime_stream(int s, servtab_t *sep UNUSED_PARAM)
1629{
1630    uint32_t result;
1631
1632    result = machtime();
1633    full_write(s, &result, sizeof(result));
1634}
1635static void FAST_FUNC machtime_dg(int s, servtab_t *sep)
1636{
1637    uint32_t result;
1638    len_and_sockaddr *lsa = alloca(LSA_LEN_SIZE + sep->se_lsa->len);
1639
1640    lsa->len = sep->se_lsa->len;
1641    if (recvfrom(s, line, LINE_SIZE, MSG_DONTWAIT, &lsa->u.sa, &lsa->len) < 0)
1642        return;
1643
1644    result = machtime();
1645    sendto(s, &result, sizeof(result), 0, &lsa->u.sa, lsa->len);
1646}
1647#endif /* FEATURE_INETD_SUPPORT_BUILTIN_TIME */
1648
1649
1650#if ENABLE_FEATURE_INETD_SUPPORT_BUILTIN_DAYTIME
1651/* Return human-readable time of day */
1652/* ARGSUSED */
1653static void FAST_FUNC daytime_stream(int s, servtab_t *sep UNUSED_PARAM)
1654{
1655    time_t t;
1656
1657    t = time(NULL);
1658    fdprintf(s, "%.24s\r\n", ctime(&t));
1659}
1660static void FAST_FUNC daytime_dg(int s, servtab_t *sep)
1661{
1662    time_t t;
1663    len_and_sockaddr *lsa = alloca(LSA_LEN_SIZE + sep->se_lsa->len);
1664
1665    lsa->len = sep->se_lsa->len;
1666    if (recvfrom(s, line, LINE_SIZE, MSG_DONTWAIT, &lsa->u.sa, &lsa->len) < 0)
1667        return;
1668
1669    t = time(NULL);
1670    sprintf(line, "%.24s\r\n", ctime(&t));
1671    sendto(s, line, strlen(line), 0, &lsa->u.sa, lsa->len);
1672}
1673#endif /* FEATURE_INETD_SUPPORT_BUILTIN_DAYTIME */
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