*
* The telnetd manpage says it all:
*
- * Telnetd operates by allocating a pseudo-terminal device (see pty(4)) for
- * a client, then creating a login process which has the slave side of the
- * pseudo-terminal as stdin, stdout, and stderr. Telnetd manipulates the
- * master side of the pseudo-terminal, implementing the telnet protocol and
- * passing characters between the remote client and the login process.
+ * Telnetd operates by allocating a pseudo-terminal device (see pty(4)) for
+ * a client, then creating a login process which has the slave side of the
+ * pseudo-terminal as stdin, stdout, and stderr. Telnetd manipulates the
+ * master side of the pseudo-terminal, implementing the telnet protocol and
+ * passing characters between the remote client and the login process.
*
* Vladimir Oleynik <dzo@simtreas.ru> 2001
- * Set process group corrections, initial busybox port
+ * Set process group corrections, initial busybox port
*/
#define DEBUG 0
#endif
#include <arpa/telnet.h>
-/* Structure that describes a session */
struct tsession {
struct tsession *next;
pid_t shell_pid;
- int sockfd_read, sockfd_write, ptyfd;
+ int sockfd_read;
+ int sockfd_write;
+ int ptyfd;
/* two circular buffers */
/*char *buf1, *buf2;*/
-/*#define TS_BUF1 ts->buf1*/
-/*#define TS_BUF2 TS_BUF2*/
-#define TS_BUF1 ((unsigned char*)(ts + 1))
-#define TS_BUF2 (((unsigned char*)(ts + 1)) + BUFSIZE)
+/*#define TS_BUF1(ts) ts->buf1*/
+/*#define TS_BUF2(ts) TS_BUF2(ts)*/
+#define TS_BUF1(ts) ((unsigned char*)(ts + 1))
+#define TS_BUF2(ts) (((unsigned char*)(ts + 1)) + BUFSIZE)
int rdidx1, wridx1, size1;
int rdidx2, wridx2, size2;
};
/* Globals */
-static int maxfd;
-static struct tsession *sessions;
-static const char *loginpath = "/bin/login";
-static const char *issuefile = "/etc/issue.net";
+struct globals {
+ struct tsession *sessions;
+ const char *loginpath;
+ const char *issuefile;
+ int maxfd;
+};
+#define G (*(struct globals*)&bb_common_bufsiz1)
+#define INIT_G() do { \
+ G.loginpath = "/bin/login"; \
+ G.issuefile = "/etc/issue.net"; \
+} while (0)
/*
static unsigned char *
remove_iacs(struct tsession *ts, int *pnum_totty)
{
- unsigned char *ptr0 = TS_BUF1 + ts->wridx1;
+ unsigned char *ptr0 = TS_BUF1(ts) + ts->wridx1;
unsigned char *ptr = ptr0;
unsigned char *totty = ptr;
unsigned char *end = ptr + MIN(BUFSIZE - ts->wridx1, ts->size1);
* TELOPT_NAWS support!
*/
if ((ptr+2) >= end) {
- /* only the beginning of the IAC is in the
+ /* Only the beginning of the IAC is in the
buffer we were asked to process, we can't
- process this char. */
+ process this char */
break;
}
/*
num_totty = totty - ptr0;
*pnum_totty = num_totty;
- /* the difference between ptr and totty is number of iacs
- we removed from the stream. Adjust buf1 accordingly. */
+ /* The difference between ptr and totty is number of iacs
+ we removed from the stream. Adjust buf1 accordingly */
if ((ptr - totty) == 0) /* 99.999% of cases */
return ptr0;
ts->wridx1 += ptr - totty;
ts->size1 -= ptr - totty;
- /* move chars meant for the terminal towards the end of the buffer */
+ /* Move chars meant for the terminal towards the end of the buffer */
return memmove(ptr - num_totty, ptr0, num_totty);
}
return total + rc;
}
+/* Must match getopt32 string */
+enum {
+ OPT_WATCHCHILD = (1 << 2), /* -K */
+ OPT_INETD = (1 << 3) * ENABLE_FEATURE_TELNETD_STANDALONE, /* -i */
+ 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 *
make_new_session(
IF_FEATURE_TELNETD_STANDALONE(int sock)
/*ts->buf1 = (char *)(ts + 1);*/
/*ts->buf2 = ts->buf1 + BUFSIZE;*/
- /* Got a new connection, set up a tty. */
+ /* Got a new connection, set up a tty */
fd = xgetpty(tty_name);
- if (fd > maxfd)
- maxfd = fd;
+ if (fd > G.maxfd)
+ G.maxfd = fd;
ts->ptyfd = fd;
ndelay_on(fd);
+ close_on_exec_on(fd);
+
#if ENABLE_FEATURE_TELNETD_STANDALONE
- ts->sockfd_read = sock;
/* SO_KEEPALIVE by popular demand */
setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, &const_int_1, sizeof(const_int_1));
+ ts->sockfd_read = sock;
ndelay_on(sock);
- if (!sock) { /* We are called with fd 0 - we are in inetd mode */
+ if (sock == 0) { /* We are called with fd 0 - we are in inetd mode */
sock++; /* so use fd 1 for output */
ndelay_on(sock);
}
ts->sockfd_write = sock;
- if (sock > maxfd)
- maxfd = sock;
+ 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));
ndelay_on(0);
ndelay_on(1);
#endif
+
/* Make the telnet client understand we will echo characters so it
* should not do it locally. We don't tell the client to run linemode,
* because we want to handle line editing and tab completion and other
};
/* This confuses iac_safe_write(), it will try to duplicate
* each IAC... */
- //memcpy(TS_BUF2, iacs_to_send, sizeof(iacs_to_send));
+ //memcpy(TS_BUF2(ts), iacs_to_send, sizeof(iacs_to_send));
//ts->rdidx2 = sizeof(iacs_to_send);
//ts->size2 = sizeof(iacs_to_send);
/* So just stuff it into TCP stream! (no error check...) */
/*ts->size2 = 0;*/
}
- fflush(NULL); /* flush all streams */
+ fflush_all();
pid = vfork(); /* NOMMU-friendly */
if (pid < 0) {
free(ts);
/* Make new session and process group */
setsid();
- /* Open the child's side of the tty. */
+ /* Open the child's side of the tty */
/* NB: setsid() disconnects from any previous ctty's. Therefore
* we must open child's side of the tty AFTER setsid! */
close(0);
xdup2(0, 2);
tcsetpgrp(0, getpid()); /* 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)). */
+ /* The pseudo-terminal allocated to the client is configured to operate
+ * in cooked mode, and with XTABS CRMOD enabled (see tty(4)) */
tcgetattr(0, &termbuf);
termbuf.c_lflag |= ECHO; /* if we use readline we dont want this */
termbuf.c_oflag |= ONLCR | XTABS;
/*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,
* (parent is supposed to read it, but parent waits
* for vforked child to exec!) */
- print_login_issue(issuefile, tty_name);
+ print_login_issue(G.issuefile, tty_name);
/* Exec shell / login / whatever */
- login_argv[0] = loginpath;
+ login_argv[0] = G.loginpath;
login_argv[1] = NULL;
/* exec busybox applet (if PREFER_APPLETS=y), if that fails,
- * exec external program */
- BB_EXECVP(loginpath, (char **)login_argv);
+ * exec external program.
+ * NB: sock is either 0 or has CLOEXEC set on it.
+ * fd has CLOEXEC set on it too. These two fds will be closed here.
+ */
+ BB_EXECVP(G.loginpath, (char **)login_argv);
/* _exit is safer with vfork, and we shouldn't send message
* to remote clients anyway */
- _exit(EXIT_FAILURE); /*bb_perror_msg_and_die("execv %s", loginpath);*/
+ _exit(EXIT_FAILURE); /*bb_perror_msg_and_die("execv %s", G.loginpath);*/
}
-/* Must match getopt32 string */
-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_FOREGROUND = (1 << 6) * ENABLE_FEATURE_TELNETD_STANDALONE, /* -F */
-};
-
#if ENABLE_FEATURE_TELNETD_STANDALONE
static void
free_session(struct tsession *ts)
{
- struct tsession *t = sessions;
+ struct tsession *t = G.sessions;
if (option_mask32 & OPT_INETD)
exit(EXIT_SUCCESS);
/* Unlink this telnet session from the session list */
if (t == ts)
- sessions = ts->next;
+ G.sessions = ts->next;
else {
while (t->next != ts)
t = t->next;
free(ts);
/* Scan all sessions and find new maxfd */
- maxfd = 0;
- ts = sessions;
+ G.maxfd = 0;
+ ts = G.sessions;
while (ts) {
- if (maxfd < ts->ptyfd)
- maxfd = ts->ptyfd;
- if (maxfd < ts->sockfd_read)
- maxfd = ts->sockfd_read;
+ if (G.maxfd < ts->ptyfd)
+ G.maxfd = ts->ptyfd;
+ if (G.maxfd < ts->sockfd_read)
+ G.maxfd = ts->sockfd_read;
#if 0
/* Again, sockfd_write == sockfd_read here */
- if (maxfd < ts->sockfd_write)
- maxfd = ts->sockfd_write;
+ if (G.maxfd < ts->sockfd_write)
+ G.maxfd = ts->sockfd_write;
#endif
ts = ts->next;
}
pid = wait_any_nohang(NULL);
if (pid <= 0)
break;
- ts = sessions;
+ ts = G.sessions;
while (ts) {
if (ts->shell_pid == pid) {
ts->shell_pid = -1;
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"),
- &issuefile, &loginpath
- IF_FEATURE_TELNETD_STANDALONE(, &opt_portnbr, &opt_bindaddr));
+ 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_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(loginpath, X_OK) here. Pointless.
- * exec will do this for us for free later. */
-
#if ENABLE_FEATURE_TELNETD_STANDALONE
if (IS_INETD) {
- sessions = make_new_session(0);
- if (!sessions) /* pty opening or vfork problem, exit */
- return 1; /* make_new_session prints error message */
+ G.sessions = make_new_session(0);
+ if (!G.sessions) /* pty opening or vfork problem, exit */
+ 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
- sessions = make_new_session();
- if (!sessions) /* pty opening or vfork problem, exit */
- return 1; /* make_new_session prints error message */
+ G.sessions = make_new_session();
+ if (!G.sessions) /* pty opening or vfork problem, exit */
+ return 1; /* make_new_session printed error message */
#endif
/* We don't want to die if just one session is broken */
signal(SIGCHLD, SIG_IGN);
/*
- This is how the buffers are used. The arrows indicate the movement
- of data.
+ This is how the buffers are used. The arrows indicate data flow.
+
+-------+ wridx1++ +------+ rdidx1++ +----------+
| | <-------------- | buf1 | <-------------- | |
| | size1-- +------+ size1++ | |
* ptys if there is room in their session buffers.
* NB: scalability problem: we recalculate entire bitmap
* before each select. Can be a problem with 500+ connections. */
- ts = sessions;
+ ts = G.sessions;
while (ts) {
- struct tsession *next = ts->next; /* in case we free ts. */
+ struct tsession *next = ts->next; /* in case we free ts */
if (ts->shell_pid == -1) {
/* Child died and we detected that */
free_session(ts);
/* This is needed because free_session() does not
* take master_fd into account when it finds new
* maxfd among remaining fd's */
- if (master_fd > maxfd)
- maxfd = master_fd;
+ if (master_fd > G.maxfd)
+ G.maxfd = master_fd;
}
- count = select(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 */
#if ENABLE_FEATURE_TELNETD_STANDALONE
- /* First check for and accept new sessions. */
+ /* Check for and accept new sessions */
if (!IS_INETD && FD_ISSET(master_fd, &rdfdset)) {
int fd;
struct tsession *new_ts;
fd = accept(master_fd, NULL, NULL);
if (fd < 0)
goto again;
- /* Create a new session and link it into our active list */
+ close_on_exec_on(fd);
+
+ /* Create a new session and link it into active list */
new_ts = make_new_session(fd);
if (new_ts) {
- new_ts->next = sessions;
- sessions = new_ts;
+ new_ts->next = G.sessions;
+ G.sessions = new_ts;
} else {
close(fd);
}
}
#endif
- /* Then check for data tunneling. */
- ts = sessions;
+ /* Then check for data tunneling */
+ ts = G.sessions;
while (ts) { /* For all sessions... */
- struct tsession *next = ts->next; /* in case we free ts. */
+ struct tsession *next = ts->next; /* in case we free ts */
if (/*ts->size1 &&*/ FD_ISSET(ts->ptyfd, &wrfdset)) {
int num_totty;
unsigned char *ptr;
- /* Write to pty from buffer 1. */
+ /* Write to pty from buffer 1 */
ptr = remove_iacs(ts, &num_totty);
count = safe_write(ts->ptyfd, ptr, num_totty);
if (count < 0) {
}
skip1:
if (/*ts->size2 &&*/ FD_ISSET(ts->sockfd_write, &wrfdset)) {
- /* Write to socket from buffer 2. */
+ /* Write to socket from buffer 2 */
count = MIN(BUFSIZE - ts->wridx2, ts->size2);
- count = iac_safe_write(ts->sockfd_write, (void*)(TS_BUF2 + ts->wridx2), count);
+ count = iac_safe_write(ts->sockfd_write, (void*)(TS_BUF2(ts) + ts->wridx2), count);
if (count < 0) {
if (errno == EAGAIN)
goto skip2;
}
if (/*ts->size1 < BUFSIZE &&*/ FD_ISSET(ts->sockfd_read, &rdfdset)) {
- /* Read from socket to buffer 1. */
+ /* Read from socket to buffer 1 */
count = MIN(BUFSIZE - ts->rdidx1, BUFSIZE - ts->size1);
- count = safe_read(ts->sockfd_read, TS_BUF1 + ts->rdidx1, count);
+ count = safe_read(ts->sockfd_read, TS_BUF1(ts) + ts->rdidx1, count);
if (count <= 0) {
if (count < 0 && errno == EAGAIN)
goto skip3;
goto kill_session;
}
/* Ignore trailing NUL if it is there */
- if (!TS_BUF1[ts->rdidx1 + count - 1]) {
+ if (!TS_BUF1(ts)[ts->rdidx1 + count - 1]) {
--count;
}
ts->size1 += count;
}
skip3:
if (/*ts->size2 < BUFSIZE &&*/ FD_ISSET(ts->ptyfd, &rdfdset)) {
- /* Read from pty to buffer 2. */
+ /* Read from pty to buffer 2 */
count = MIN(BUFSIZE - ts->rdidx2, BUFSIZE - ts->size2);
- count = safe_read(ts->ptyfd, TS_BUF2 + ts->rdidx2, count);
+ count = safe_read(ts->ptyfd, TS_BUF2(ts) + ts->rdidx2, count);
if (count <= 0) {
if (count < 0 && errno == EAGAIN)
goto skip4;
projects / oweals / busybox.git / blobdiff