summaryrefslogtreecommitdiff
path: root/networking/telnetd.c
diff options
context:
space:
mode:
Diffstat (limited to 'networking/telnetd.c')
-rw-r--r--networking/telnetd.c157
1 files changed, 94 insertions, 63 deletions
diff --git a/networking/telnetd.c b/networking/telnetd.c
index b7162ad..6a8190b 100644
--- a/networking/telnetd.c
+++ b/networking/telnetd.c
@@ -11,14 +11,14 @@
*
* 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
@@ -40,10 +40,10 @@ struct tsession {
/* 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;
};
@@ -54,10 +54,17 @@ enum { BUFSIZE = (4 * 1024 - sizeof(struct tsession)) / 2 };
/* 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)
/*
@@ -81,7 +88,7 @@ static const char *issuefile = "/etc/issue.net";
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);
@@ -199,9 +206,17 @@ static size_t iac_safe_write(int fd, const char *buf, size_t count)
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 */
+ OPT_FOREGROUND = (1 << 6) * ENABLE_FEATURE_TELNETD_STANDALONE, /* -F */
+};
+
static struct tsession *
make_new_session(
- IF_FEATURE_TELNETD_STANDALONE(int sock)
+ IF_FEATURE_TELNETD_STANDALONE(int master_fd, int sock)
IF_NOT_FEATURE_TELNETD_STANDALONE(void)
) {
const char *login_argv[2];
@@ -215,8 +230,8 @@ make_new_session(
/* 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);
#if ENABLE_FEATURE_TELNETD_STANDALONE
@@ -229,8 +244,8 @@ make_new_session(
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));
@@ -254,7 +269,7 @@ make_new_session(
};
/* 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...) */
@@ -288,13 +303,35 @@ make_new_session(
/* Restore default signal handling ASAP */
bb_signals((1 << SIGCHLD) + (1 << SIGPIPE), SIG_DFL);
+#if ENABLE_FEATURE_TELNETD_STANDALONE
+ if (!(option_mask32 & OPT_INETD)) {
+ struct tsession *tp = G.sessions;
+ while (tp) {
+ close(tp->ptyfd);
+ close(tp->sockfd_read);
+ /* sockfd_write == sockfd_read for standalone telnetd */
+ /*close(tp->sockfd_write);*/
+ tp = tp->next;
+ }
+ }
+#endif
+
/* Make new session and process group */
setsid();
+ close(fd);
+#if ENABLE_FEATURE_TELNETD_STANDALONE
+ if (master_fd >= 0)
+ close(master_fd);
+ close(sock);
+#endif
/* 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);
+#if ENABLE_FEATURE_TELNETD_STANDALONE
+ if (sock != 0) /* if we did not close 0 already */
+#endif
+ close(0);
xopen(tty_name, O_RDWR); /* becomes our ctty */
xdup2(0, 1);
xdup2(0, 2);
@@ -316,40 +353,32 @@ make_new_session(
* 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);
+ 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;
@@ -371,17 +400,17 @@ free_session(struct tsession *ts)
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;
}
@@ -404,7 +433,7 @@ static void handle_sigchld(int sig UNUSED_PARAM)
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;
@@ -435,10 +464,12 @@ int telnetd_main(int argc UNUSED_PARAM, char **argv)
portnbr = 23,
};
#endif
+ INIT_G();
+
/* 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
+ &G.issuefile, &G.loginpath
IF_FEATURE_TELNETD_STANDALONE(, &opt_portnbr, &opt_bindaddr));
if (!IS_INETD /*&& !re_execed*/) {
/* inform that we start in standalone mode?
@@ -460,21 +491,21 @@ int telnetd_main(int argc UNUSED_PARAM, char **argv)
portnbr = xatou16(opt_portnbr);
);
- /* Used to check access(loginpath, X_OK) here. Pointless.
+ /* 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) {
- sessions = make_new_session(0);
- if (!sessions) /* pty opening or vfork problem, exit */
+ G.sessions = make_new_session(-1, 0);
+ if (!G.sessions) /* pty opening or vfork problem, exit */
return 1; /* make_new_session prints error message */
} else {
master_fd = create_and_bind_stream_or_die(opt_bindaddr, portnbr);
xlisten(master_fd, 1);
}
#else
- sessions = make_new_session();
- if (!sessions) /* pty opening or vfork problem, exit */
+ G.sessions = make_new_session();
+ if (!G.sessions) /* pty opening or vfork problem, exit */
return 1; /* make_new_session prints error message */
#endif
@@ -512,7 +543,7 @@ int telnetd_main(int argc UNUSED_PARAM, char **argv)
* 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. */
if (ts->shell_pid == -1) {
@@ -535,11 +566,11 @@ int telnetd_main(int argc UNUSED_PARAM, char **argv)
/* 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);
+ count = select(G.maxfd + 1, &rdfdset, &wrfdset, NULL, NULL);
if (count < 0)
goto again; /* EINTR or ENOMEM */
@@ -553,10 +584,10 @@ int telnetd_main(int argc UNUSED_PARAM, char **argv)
if (fd < 0)
goto again;
/* Create a new session and link it into our active list */
- new_ts = make_new_session(fd);
+ new_ts = make_new_session(master_fd, fd);
if (new_ts) {
- new_ts->next = sessions;
- sessions = new_ts;
+ new_ts->next = G.sessions;
+ G.sessions = new_ts;
} else {
close(fd);
}
@@ -564,7 +595,7 @@ int telnetd_main(int argc UNUSED_PARAM, char **argv)
#endif
/* Then check for data tunneling. */
- ts = sessions;
+ ts = G.sessions;
while (ts) { /* For all sessions... */
struct tsession *next = ts->next; /* in case we free ts. */
@@ -588,7 +619,7 @@ int telnetd_main(int argc UNUSED_PARAM, char **argv)
if (/*ts->size2 &&*/ FD_ISSET(ts->sockfd_write, &wrfdset)) {
/* 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;
@@ -618,14 +649,14 @@ int telnetd_main(int argc UNUSED_PARAM, char **argv)
if (/*ts->size1 < BUFSIZE &&*/ FD_ISSET(ts->sockfd_read, &rdfdset)) {
/* 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;
@@ -637,7 +668,7 @@ int telnetd_main(int argc UNUSED_PARAM, char **argv)
if (/*ts->size2 < BUFSIZE &&*/ FD_ISSET(ts->ptyfd, &rdfdset)) {
/* 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;
generated by cgit v1.1 at 2024-11-05 16:44:57 +0000