emo/busybox
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

telnetd: add -w ("inetd wait") option. Can be configured off.

Browse Source 
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>
This commit is contained in:
Denys Vlasenko
2009-09-04 02:21:13 +02:00
parent cfc216345e
commit ed1667e8ee
3 changed files with 69 additions and 28 deletions
Download Patch File Download Diff File Expand all files Collapse all files

21
networking/Config.in
View File

@@ -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

56
networking/telnetd.c
View File

@@ -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 */