* 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.
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 timeval tv;
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 */
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;
}