[git commit master] telnetd: add -w ("inetd wait") option. Can be configured off.
Denys Vlasenko
vda.linux at googlemail.com
Fri Sep 4 00:21:13 UTC 2009
commit: http://git.busybox.net/busybox/commit/?id=ed1667e8ee91243b77b02cc4f160fe4b80a30385
branch: http://git.busybox.net/busybox/commit/?id=refs/heads/master
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 at googlemail.com>
---
include/usage.h | 20 ++++++++++-------
networking/Config.in | 21 ++++++++++++++++++
networking/telnetd.c | 56 ++++++++++++++++++++++++++++++++-----------------
3 files changed, 69 insertions(+), 28 deletions(-)
diff --git a/include/usage.h b/include/usage.h
index ba77490..9fa1b9e 100644
--- a/include/usage.h
+++ b/include/usage.h
@@ -1468,11 +1468,11 @@
"\n -m Get baud rate from modem's CONNECT status message" \
"\n -w Wait for a CR or LF before sending /etc/issue" \
"\n -n Do not prompt the user for a login name" \
- "\n -f issue_file Display issue_file instead of /etc/issue" \
- "\n -l login_app Invoke login_app instead of /bin/login" \
- "\n -t timeout Terminate after timeout if no username is read" \
- "\n -I initstring Init string to send before anything else" \
- "\n -H login_host Log login_host into the utmp file as the hostname" \
+ "\n -f ISSUE_FILE Display ISSUE_FILE instead of /etc/issue" \
+ "\n -l LOGIN Invoke LOGIN instead of /bin/login" \
+ "\n -t SEC Terminate after SEC if no username is read" \
+ "\n -I INITSTR Send INITSTR before anything else" \
+ "\n -H HOST Log HOST into the utmp file as the hostname" \
#define grep_trivial_usage \
"[-HhrilLnqvso" \
@@ -4415,14 +4415,18 @@
IF_NOT_FEATURE_TELNETD_STANDALONE(" via inetd") "\n" \
"\nOptions:" \
"\n -l LOGIN Exec LOGIN on connect" \
- "\n -f issue_file Display issue_file instead of /etc/issue" \
+ "\n -f ISSUE_FILE Display ISSUE_FILE instead of /etc/issue" \
"\n -K Close connection as soon as login exits" \
"\n (normally wait until all programs close slave pty)" \
IF_FEATURE_TELNETD_STANDALONE( \
"\n -p PORT Port to listen on" \
- "\n -b ADDR Address to bind to" \
+ "\n -b ADDR[:PORT] Address to bind to" \
"\n -F Run in foreground" \
- "\n -i Run as inetd subservice" \
+ "\n -i Run as inetd service" \
+ IF_FEATURE_TELNETD_INETD_WAIT( \
+ "\n -w SEC Run as inetd service in wait mode, linger time SEC" \
+ "\n -S Log to syslog (implied by -i or without -F and -w)" \
+ ) \
)
/* "test --help" does not print help (POSIX compat), only "[ --help" does.
diff --git a/networking/Config.in b/networking/Config.in
index 83522ff..59e88e0 100644
--- a/networking/Config.in
+++ b/networking/Config.in
@@ -788,6 +788,27 @@ config FEATURE_TELNETD_STANDALONE
help
Selecting this will make telnetd able to run standalone.
+config FEATURE_TELNETD_INETD_WAIT
+ bool "Support -w SEC option (inetd wait mode)"
+ default n
+ depends on FEATURE_TELNETD_STANDALONE
+ help
+ This option allows you to run telnetd in "inet wait" mode.
+ Example inetd.conf line (note "wait", not usual "nowait"):
+
+ telnet stream tcp wait root /bin/telnetd telnetd -w10
+
+ In this example, inetd passes _listening_ socket_ as fd 0
+ to telnetd when connection appears.
+ telnetd will wait for connections until all existing
+ connections are closed, and no new connections
+ appear during 10 seconds. Then it exits, and inetd continues
+ to listen for new connections.
+
+ This option is rarely used. "tcp nowait" is much more usual
+ way of running tcp services, including telnetd.
+ You most probably want to say N here.
+
config TFTP
bool "tftp"
default n
diff --git a/networking/telnetd.c b/networking/telnetd.c
index 540387f..2a0ace5 100644
--- a/networking/telnetd.c
+++ b/networking/telnetd.c
@@ -211,8 +211,10 @@ static size_t iac_safe_write(int fd, const char *buf, size_t count)
enum {
OPT_WATCHCHILD = (1 << 2), /* -K */
OPT_INETD = (1 << 3) * ENABLE_FEATURE_TELNETD_STANDALONE, /* -i */
- OPT_PORT = (1 << 4) * ENABLE_FEATURE_TELNETD_STANDALONE, /* -p */
+ OPT_PORT = (1 << 4) * ENABLE_FEATURE_TELNETD_STANDALONE, /* -p PORT */
OPT_FOREGROUND = (1 << 6) * ENABLE_FEATURE_TELNETD_STANDALONE, /* -F */
+ OPT_SYSLOG = (1 << 7) * ENABLE_FEATURE_TELNETD_INETD_WAIT, /* -S */
+ OPT_WAIT = (1 << 8) * ENABLE_FEATURE_TELNETD_INETD_WAIT, /* -w SEC */
};
static struct tsession *
@@ -438,24 +440,29 @@ int telnetd_main(int argc UNUSED_PARAM, char **argv)
struct tsession *ts;
#if ENABLE_FEATURE_TELNETD_STANDALONE
#define IS_INETD (opt & OPT_INETD)
- int master_fd = master_fd; /* be happy, gcc */
- unsigned portnbr = 23;
+ int master_fd = master_fd; /* for compiler */
+ int sec_linger = sec_linger;
char *opt_bindaddr = NULL;
char *opt_portnbr;
#else
enum {
IS_INETD = 1,
master_fd = -1,
- portnbr = 23,
};
#endif
INIT_G();
+ /* -w NUM, and implies -F. -w and -i don't mix */
+ IF_FEATURE_TELNETD_INETD_WAIT(opt_complementary = "wF:w+:i--w:w--i";)
/* Even if !STANDALONE, we accept (and ignore) -i, thus people
* don't need to guess whether it's ok to pass -i to us */
- opt = getopt32(argv, "f:l:Ki" IF_FEATURE_TELNETD_STANDALONE("p:b:F"),
+ opt = getopt32(argv, "f:l:Ki"
+ IF_FEATURE_TELNETD_STANDALONE("p:b:F")
+ IF_FEATURE_TELNETD_INETD_WAIT("Sw:"),
&G.issuefile, &G.loginpath
- IF_FEATURE_TELNETD_STANDALONE(, &opt_portnbr, &opt_bindaddr));
+ IF_FEATURE_TELNETD_STANDALONE(, &opt_portnbr, &opt_bindaddr)
+ IF_FEATURE_TELNETD_INETD_WAIT(, &sec_linger)
+ );
if (!IS_INETD /*&& !re_execed*/) {
/* inform that we start in standalone mode?
* May be useful when people forget to give -i */
@@ -467,32 +474,30 @@ int telnetd_main(int argc UNUSED_PARAM, char **argv)
}
}
/* Redirect log to syslog early, if needed */
- if (IS_INETD || !(opt & OPT_FOREGROUND)) {
+ if (IS_INETD || (opt & OPT_SYSLOG) || !(opt & OPT_FOREGROUND)) {
openlog(applet_name, LOG_PID, LOG_DAEMON);
logmode = LOGMODE_SYSLOG;
}
- IF_FEATURE_TELNETD_STANDALONE(
- if (opt & OPT_PORT)
- portnbr = xatou16(opt_portnbr);
- );
-
- /* Used to check access(G.loginpath, X_OK) here. Pointless.
- * exec will do this for us for free later. */
-
#if ENABLE_FEATURE_TELNETD_STANDALONE
if (IS_INETD) {
G.sessions = make_new_session(0);
if (!G.sessions) /* pty opening or vfork problem, exit */
- return 1; /* make_new_session prints error message */
+ return 1; /* make_new_session printed error message */
} else {
- master_fd = create_and_bind_stream_or_die(opt_bindaddr, portnbr);
- xlisten(master_fd, 1);
+ master_fd = 0;
+ if (!(opt & OPT_WAIT)) {
+ unsigned portnbr = 23;
+ if (opt & OPT_PORT)
+ portnbr = xatou16(opt_portnbr);
+ master_fd = create_and_bind_stream_or_die(opt_bindaddr, portnbr);
+ xlisten(master_fd, 1);
+ }
close_on_exec_on(master_fd);
}
#else
G.sessions = make_new_session();
if (!G.sessions) /* pty opening or vfork problem, exit */
- return 1; /* make_new_session prints error message */
+ return 1; /* make_new_session printed error message */
#endif
/* We don't want to die if just one session is broken */
@@ -556,7 +561,18 @@ int telnetd_main(int argc UNUSED_PARAM, char **argv)
G.maxfd = master_fd;
}
- count = select(G.maxfd + 1, &rdfdset, &wrfdset, NULL, NULL);
+ {
+ struct timeval tv;
+ struct timeval *tv_ptr = NULL;
+ if ((opt & OPT_WAIT) && !G.sessions) {
+ tv.tv_sec = sec_linger;
+ tv.tv_usec = 0;
+ tv_ptr = &tv;
+ }
+ count = select(G.maxfd + 1, &rdfdset, &wrfdset, NULL, tv_ptr);
+ }
+ if (count == 0) /* "telnetd -w SEC" timed out */
+ return 0;
if (count < 0)
goto again; /* EINTR or ENOMEM */
--
1.6.3.3
More information about the busybox-cvs
mailing list