* 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
* Set process group corrections, initial busybox port
*/
+//usage:#define telnetd_trivial_usage
+//usage: "[OPTIONS]"
+//usage:#define telnetd_full_usage "\n\n"
+//usage: "Handle incoming telnet connections"
+//usage: IF_NOT_FEATURE_TELNETD_STANDALONE(" via inetd") "\n"
+//usage: "\n -l LOGIN Exec LOGIN on connect"
+//usage: "\n -f ISSUE_FILE Display ISSUE_FILE instead of /etc/issue"
+//usage: "\n -K Close connection as soon as login exits"
+//usage: "\n (normally wait until all programs close slave pty)"
+//usage: IF_FEATURE_TELNETD_STANDALONE(
+//usage: "\n -p PORT Port to listen on"
+//usage: "\n -b ADDR[:PORT] Address to bind to"
+//usage: "\n -F Run in foreground"
+//usage: "\n -i Inetd mode"
+//usage: IF_FEATURE_TELNETD_INETD_WAIT(
+//usage: "\n -w SEC Inetd 'wait' mode, linger time SEC"
+//usage: "\n -S Log to syslog (implied by -i or without -F and -w)"
+//usage: )
+//usage: )
+
#define DEBUG 0
#include "libbb.h"
#include <syslog.h>
#if DEBUG
-#define TELCMDS
-#define TELOPTS
+# define TELCMDS
+# define TELOPTS
#endif
#include <arpa/telnet.h>
+
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 (ptr[1] == SB && ptr[2] == TELOPT_NAWS) {
struct winsize ws;
if ((ptr+8) >= end)
- break; /* incomplete, can't process */
+ break; /* incomplete, can't process */
ws.ws_col = (ptr[3] << 8) | ptr[4];
ws.ws_row = (ptr[5] << 8) | ptr[6];
ioctl(ts->ptyfd, TIOCSWINSZ, (char *)&ws);
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);
static const char iacs_to_send[] ALIGN1 = {
IAC, DO, TELOPT_ECHO,
IAC, DO, TELOPT_NAWS,
- /* This requires telnetd.ctrlSQ.patch (incomplete) */
- /* IAC, DO, TELOPT_LFLOW, */
+ /* This requires telnetd.ctrlSQ.patch (incomplete) */
+ /*IAC, DO, TELOPT_LFLOW,*/
IAC, WILL, TELOPT_ECHO,
IAC, WILL, TELOPT_SGA
};
/*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);
+ pid = getpid();
+
+ 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 */
+ 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;
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