* Simple telnet server
* Bjorn Wesen, Axis Communications AB (bjornw@axis.com)
*
- * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
+ * Licensed under GPLv2 or later, see file LICENSE in this source tree.
*
* ---------------------------------------------------------------------------
* (C) Copyright 2000, Axis Communications AB, LUND, SWEDEN
* Vladimir Oleynik <dzo@simtreas.ru> 2001
* Set process group corrections, initial busybox port
*/
-
#define DEBUG 0
#include "libbb.h"
#include <syslog.h>
#if DEBUG
-#define TELCMDS
-#define TELOPTS
+# define TELCMDS
+# define TELOPTS
#endif
#include <arpa/telnet.h>
+#if ENABLE_FEATURE_UTMP
+# include <utmp.h> /* LOGIN_PROCESS */
+#endif
+
+
struct tsession {
struct tsession *next;
pid_t shell_pid;
const char *loginpath;
const char *issuefile;
int maxfd;
-};
+} FIX_ALIASING;
#define G (*(struct globals*)&bb_common_bufsiz1)
#define INIT_G() do { \
G.loginpath = "/bin/login"; \
string of characters fit for the terminal. Do this by packing
all characters meant for the terminal sequentially towards the end of buf.
- Return a pointer to the beginning of the characters meant for the terminal.
+ Return a pointer to the beginning of the characters meant for the terminal
and make *num_totty the number of characters that should be sent to
the terminal.
- Note - If an IAC (3 byte quantity) starts before (bf + len) but extends
+ Note - if an IAC (3 byte quantity) starts before (bf + len) but extends
past (bf + len) then that IAC will be left unprocessed and *processed
will be less than len.
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 *
IF_FEATURE_TELNETD_STANDALONE(int sock)
IF_NOT_FEATURE_TELNETD_STANDALONE(void)
) {
+#if !ENABLE_FEATURE_TELNETD_STANDALONE
+ enum { sock = 0 };
+#endif
const char *login_argv[2];
struct termios termbuf;
int fd, pid;
ndelay_on(fd);
close_on_exec_on(fd);
-#if ENABLE_FEATURE_TELNETD_STANDALONE
/* SO_KEEPALIVE by popular demand */
setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, &const_int_1, sizeof(const_int_1));
+#if ENABLE_FEATURE_TELNETD_STANDALONE
ts->sockfd_read = sock;
ndelay_on(sock);
if (sock == 0) { /* We are called with fd 0 - we are in inetd mode */
if (sock > G.maxfd)
G.maxfd = sock;
#else
- /* SO_KEEPALIVE by popular demand */
- setsockopt(0, SOL_SOCKET, SO_KEEPALIVE, &const_int_1, sizeof(const_int_1));
/* ts->sockfd_read = 0; - done by xzalloc */
ts->sockfd_write = 1;
ndelay_on(0);
/*ts->size2 = 0;*/
}
- fflush(NULL); /* flush all streams */
+ fflush_all();
pid = vfork(); /* NOMMU-friendly */
if (pid < 0) {
free(ts);
/* Restore default signal handling ASAP */
bb_signals((1 << SIGCHLD) + (1 << SIGPIPE), SIG_DFL);
+ if (ENABLE_FEATURE_UTMP) {
+ len_and_sockaddr *lsa = get_peer_lsa(sock);
+ char *hostname = NULL;
+ if (lsa) {
+ hostname = xmalloc_sockaddr2dotted(&lsa->u.sa);
+ free(lsa);
+ }
+ write_new_utmp(pid, LOGIN_PROCESS, tty_name, /*username:*/ "LOGIN", hostname);
+ free(hostname);
+ }
+
/* Make new session and process group */
setsid();
xopen(tty_name, O_RDWR); /* becomes our ctty */
xdup2(0, 1);
xdup2(0, 2);
- tcsetpgrp(0, getpid()); /* switch this tty's process group to us */
+ pid = getpid();
+ tcsetpgrp(0, pid); /* switch this tty's process group to us */
/* The pseudo-terminal allocated to the client is configured to operate
* in cooked mode, and with XTABS CRMOD enabled (see tty(4)) */
/*termbuf.c_lflag &= ~ICANON;*/
tcsetattr_stdin_TCSANOW(&termbuf);
- /* Uses FILE-based I/O to stdout, but does fflush(stdout),
+ /* Uses FILE-based I/O to stdout, but does fflush_all(),
* so should be safe with vfork.
* I fear, though, that some users will have ridiculously big
* issue files, and they may block writing to fd 1,
static void
free_session(struct tsession *ts)
{
- struct tsession *t = G.sessions;
+ struct tsession *t;
if (option_mask32 & OPT_INETD)
exit(EXIT_SUCCESS);
/* Unlink this telnet session from the session list */
+ t = G.sessions;
if (t == ts)
G.sessions = ts->next;
else {
{
pid_t pid;
struct tsession *ts;
+ int save_errno = errno;
/* Looping: more than one child may have exited */
while (1) {
while (ts) {
if (ts->shell_pid == pid) {
ts->shell_pid = -1;
+// man utmp:
+// When init(8) finds that a process has exited, it locates its utmp entry
+// by ut_pid, sets ut_type to DEAD_PROCESS, and clears ut_user, ut_host
+// and ut_time with null bytes.
+// [same applies to other processes which maintain utmp entries, like telnetd]
+//
+// We do not bother actually clearing fields:
+// it might be interesting to know who was logged in and from where
+ update_utmp(pid, DEAD_PROCESS, /*tty_name:*/ NULL, /*username:*/ NULL, /*hostname:*/ NULL);
break;
}
ts = ts->next;
}
}
+
+ errno = save_errno;
}
int telnetd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
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 */
}
}
/* 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 */
G.maxfd = master_fd;
}
- count = select(G.maxfd + 1, &rdfdset, &wrfdset, NULL, NULL);
+ {
+ struct timeval *tv_ptr = NULL;
+#if ENABLE_FEATURE_TELNETD_INETD_WAIT
+ struct timeval tv;
+ if ((opt & OPT_WAIT) && !G.sessions) {
+ tv.tv_sec = sec_linger;
+ tv.tv_usec = 0;
+ tv_ptr = &tv;
+ }
+#endif
+ 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 */
ts = next;
continue;
kill_session:
+ if (ts->shell_pid > 0)
+ update_utmp(ts->shell_pid, DEAD_PROCESS, /*tty_name:*/ NULL, /*username:*/ NULL, /*hostname:*/ NULL);
free_session(ts);
ts = next;
}
projects / oweals / busybox.git / blobdiff