telnetd: add -w ("inetd wait") option. Can be configured off.
gcc fils to fully optimize it out when it's off: function old new delta telnetd_main 1527 1548 +21 packed_usage 26596 26587 -9 but nevertheless it's a useful (and so far single) example how to write "inetd wait" tcp service. Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
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Denys Vlasenko
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cfc216345e
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@ -1468,11 +1468,11 @@
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"\n -m Get baud rate from modem's CONNECT status message" \
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"\n -w Wait for a CR or LF before sending /etc/issue" \
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"\n -n Do not prompt the user for a login name" \
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"\n -f issue_file Display issue_file instead of /etc/issue" \
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"\n -l login_app Invoke login_app instead of /bin/login" \
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"\n -t timeout Terminate after timeout if no username is read" \
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"\n -I initstring Init string to send before anything else" \
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"\n -H login_host Log login_host into the utmp file as the hostname" \
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"\n -f ISSUE_FILE Display ISSUE_FILE instead of /etc/issue" \
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"\n -l LOGIN Invoke LOGIN instead of /bin/login" \
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"\n -t SEC Terminate after SEC if no username is read" \
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"\n -I INITSTR Send INITSTR before anything else" \
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"\n -H HOST Log HOST into the utmp file as the hostname" \
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#define grep_trivial_usage \
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"[-HhrilLnqvso" \
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@ -4415,14 +4415,18 @@
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IF_NOT_FEATURE_TELNETD_STANDALONE(" via inetd") "\n" \
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"\nOptions:" \
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"\n -l LOGIN Exec LOGIN on connect" \
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"\n -f issue_file Display issue_file instead of /etc/issue" \
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"\n -f ISSUE_FILE Display ISSUE_FILE instead of /etc/issue" \
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"\n -K Close connection as soon as login exits" \
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"\n (normally wait until all programs close slave pty)" \
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IF_FEATURE_TELNETD_STANDALONE( \
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"\n -p PORT Port to listen on" \
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"\n -b ADDR Address to bind to" \
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"\n -b ADDR[:PORT] Address to bind to" \
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"\n -F Run in foreground" \
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"\n -i Run as inetd subservice" \
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"\n -i Run as inetd service" \
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IF_FEATURE_TELNETD_INETD_WAIT( \
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"\n -w SEC Run as inetd service in wait mode, linger time SEC" \
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"\n -S Log to syslog (implied by -i or without -F and -w)" \
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) \
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)
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/* "test --help" does not print help (POSIX compat), only "[ --help" does.
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@ -788,6 +788,27 @@ config FEATURE_TELNETD_STANDALONE
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help
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Selecting this will make telnetd able to run standalone.
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config FEATURE_TELNETD_INETD_WAIT
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bool "Support -w SEC option (inetd wait mode)"
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default n
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depends on FEATURE_TELNETD_STANDALONE
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help
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This option allows you to run telnetd in "inet wait" mode.
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Example inetd.conf line (note "wait", not usual "nowait"):
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telnet stream tcp wait root /bin/telnetd telnetd -w10
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In this example, inetd passes _listening_ socket_ as fd 0
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to telnetd when connection appears.
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telnetd will wait for connections until all existing
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connections are closed, and no new connections
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appear during 10 seconds. Then it exits, and inetd continues
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to listen for new connections.
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This option is rarely used. "tcp nowait" is much more usual
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way of running tcp services, including telnetd.
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You most probably want to say N here.
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config TFTP
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bool "tftp"
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default n
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@ -211,8 +211,10 @@ static size_t iac_safe_write(int fd, const char *buf, size_t count)
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enum {
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OPT_WATCHCHILD = (1 << 2), /* -K */
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OPT_INETD = (1 << 3) * ENABLE_FEATURE_TELNETD_STANDALONE, /* -i */
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OPT_PORT = (1 << 4) * ENABLE_FEATURE_TELNETD_STANDALONE, /* -p */
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OPT_PORT = (1 << 4) * ENABLE_FEATURE_TELNETD_STANDALONE, /* -p PORT */
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OPT_FOREGROUND = (1 << 6) * ENABLE_FEATURE_TELNETD_STANDALONE, /* -F */
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OPT_SYSLOG = (1 << 7) * ENABLE_FEATURE_TELNETD_INETD_WAIT, /* -S */
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OPT_WAIT = (1 << 8) * ENABLE_FEATURE_TELNETD_INETD_WAIT, /* -w SEC */
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};
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static struct tsession *
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@ -438,24 +440,29 @@ int telnetd_main(int argc UNUSED_PARAM, char **argv)
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struct tsession *ts;
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#if ENABLE_FEATURE_TELNETD_STANDALONE
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#define IS_INETD (opt & OPT_INETD)
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int master_fd = master_fd; /* be happy, gcc */
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unsigned portnbr = 23;
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int master_fd = master_fd; /* for compiler */
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int sec_linger = sec_linger;
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char *opt_bindaddr = NULL;
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char *opt_portnbr;
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#else
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enum {
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IS_INETD = 1,
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master_fd = -1,
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portnbr = 23,
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};
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#endif
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INIT_G();
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/* -w NUM, and implies -F. -w and -i don't mix */
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IF_FEATURE_TELNETD_INETD_WAIT(opt_complementary = "wF:w+:i--w:w--i";)
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/* Even if !STANDALONE, we accept (and ignore) -i, thus people
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* don't need to guess whether it's ok to pass -i to us */
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opt = getopt32(argv, "f:l:Ki" IF_FEATURE_TELNETD_STANDALONE("p:b:F"),
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opt = getopt32(argv, "f:l:Ki"
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IF_FEATURE_TELNETD_STANDALONE("p:b:F")
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IF_FEATURE_TELNETD_INETD_WAIT("Sw:"),
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&G.issuefile, &G.loginpath
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IF_FEATURE_TELNETD_STANDALONE(, &opt_portnbr, &opt_bindaddr));
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IF_FEATURE_TELNETD_STANDALONE(, &opt_portnbr, &opt_bindaddr)
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IF_FEATURE_TELNETD_INETD_WAIT(, &sec_linger)
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);
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if (!IS_INETD /*&& !re_execed*/) {
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/* inform that we start in standalone mode?
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* May be useful when people forget to give -i */
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@ -467,32 +474,30 @@ int telnetd_main(int argc UNUSED_PARAM, char **argv)
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}
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}
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/* Redirect log to syslog early, if needed */
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if (IS_INETD || !(opt & OPT_FOREGROUND)) {
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if (IS_INETD || (opt & OPT_SYSLOG) || !(opt & OPT_FOREGROUND)) {
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openlog(applet_name, LOG_PID, LOG_DAEMON);
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logmode = LOGMODE_SYSLOG;
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}
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IF_FEATURE_TELNETD_STANDALONE(
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if (opt & OPT_PORT)
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portnbr = xatou16(opt_portnbr);
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);
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/* Used to check access(G.loginpath, X_OK) here. Pointless.
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* exec will do this for us for free later. */
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#if ENABLE_FEATURE_TELNETD_STANDALONE
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if (IS_INETD) {
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G.sessions = make_new_session(0);
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if (!G.sessions) /* pty opening or vfork problem, exit */
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return 1; /* make_new_session prints error message */
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return 1; /* make_new_session printed error message */
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} else {
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master_fd = create_and_bind_stream_or_die(opt_bindaddr, portnbr);
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xlisten(master_fd, 1);
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master_fd = 0;
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if (!(opt & OPT_WAIT)) {
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unsigned portnbr = 23;
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if (opt & OPT_PORT)
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portnbr = xatou16(opt_portnbr);
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master_fd = create_and_bind_stream_or_die(opt_bindaddr, portnbr);
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xlisten(master_fd, 1);
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}
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close_on_exec_on(master_fd);
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}
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#else
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G.sessions = make_new_session();
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if (!G.sessions) /* pty opening or vfork problem, exit */
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return 1; /* make_new_session prints error message */
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return 1; /* make_new_session printed error message */
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#endif
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/* We don't want to die if just one session is broken */
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@ -556,7 +561,18 @@ int telnetd_main(int argc UNUSED_PARAM, char **argv)
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G.maxfd = master_fd;
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}
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count = select(G.maxfd + 1, &rdfdset, &wrfdset, NULL, NULL);
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{
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struct timeval tv;
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struct timeval *tv_ptr = NULL;
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if ((opt & OPT_WAIT) && !G.sessions) {
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tv.tv_sec = sec_linger;
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tv.tv_usec = 0;
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tv_ptr = &tv;
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}
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count = select(G.maxfd + 1, &rdfdset, &wrfdset, NULL, tv_ptr);
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}
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if (count == 0) /* "telnetd -w SEC" timed out */
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return 0;
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if (count < 0)
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goto again; /* EINTR or ENOMEM */
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