176 lines
6.5 KiB
Diff
176 lines
6.5 KiB
Diff
From: "Doug Graham" <dgraham@nortel.com>
|
|
Date: 2009-01-22 07:20
|
|
|
|
Hello,
|
|
|
|
Busybox's telnetd does not disable local (client-side) flow control
|
|
properly. It does not put the pty into packet mode and then notify the
|
|
client whenever flow control is disabled by an application running under
|
|
its control. The result is that ^S/^Q are not passed through to the
|
|
application, which is painful when the application is an emacs variant.
|
|
|
|
I suppose that support for this might be considered bloat, but the
|
|
included patch only adds about 200 bytes of text to x86 busybox and 300
|
|
bytes to mipsel busybox. Please consider applying.
|
|
|
|
=============================
|
|
|
|
NB: the patch doesn't work as-is because we now have iac_safe_write()
|
|
which quotes IACs on output.
|
|
|
|
=============================
|
|
Docs:
|
|
|
|
The following ioctl(2) calls apply only to pseudo terminals:
|
|
|
|
TIOCSTOP Stops output to a terminal (e.g. like typing ^S). Takes no parameter.
|
|
|
|
TIOCSTART Restarts output (stopped by TIOCSTOP or by typing ^S). Takes no parameter.
|
|
|
|
TIOCPKT Enable/disable packet mode. When applied to the master side of a pseudo terminal, each
|
|
subsequent read(2) from the terminal will return data written on the slave part of the pseudo terminal preceded by a
|
|
zero byte (symbolically defined as TIOCPKT_DATA), or a single byte reflecting control status information.
|
|
In the latter case, the byte is an inclusive-or of zero or more of the bits:
|
|
|
|
TIOCPKT_FLUSHREAD whenever the read queue for the terminal is flushed.
|
|
TIOCPKT_FLUSHWRITE whenever the write queue for the terminal is flushed.
|
|
TIOCPKT_STOP whenever output to the terminal is stopped a la ^S.
|
|
TIOCPKT_START whenever output to the terminal is restarted.
|
|
TIOCPKT_DOSTOP whenever t_stopc is ^S and t_startc is ^Q.
|
|
TIOCPKT_NOSTOP whenever the start and stop characters are not ^S/^Q.
|
|
|
|
While this mode is in use, the presence of control status information to be read from the master side may be detected
|
|
by a select(2) for exceptional conditions.
|
|
|
|
This mode is used by rlogin(1) and rlogind(8) to implement a remote-echoed, locally ^S/^Q flow-controlled remote login
|
|
with proper back-flushing of output; it can be used by other similar programs.
|
|
|
|
TIOCUCNTL Enable/disable a mode that allows a small number of simple user ioctl(2) commands to be passed through
|
|
the pseudo-terminal, using a protocol similar to that of TIOCPKT. The TIOCUCNTL and TIOCPKT modes are mutually
|
|
exclusive. This mode is enabled from the master side of a pseudo terminal. Each subsequent read(2) from the master side
|
|
will return data written on the slave part of the pseudo terminal preceded by a zero byte, or a single byte reflecting a
|
|
user control operation on the slave side. A user control command consists of a special ioctl(2) operation with no data;
|
|
the command is given as UIOCCMD (n), where n is a number in the range 1-255. The operation value n will be received as
|
|
a single byte on the next read(2) from the master side. The ioctl(2) UIOCCMD (0) is a no-op that may be used to probe
|
|
for the existence of this facility. As with TIOCPKT mode, command operations may be detected with a select(2) for
|
|
exceptional conditions.
|
|
|
|
--- busybox-1.13.2/networking/telnetd.c 2009/01/21 20:02:39 1.1
|
|
+++ busybox-1.13.2/networking/telnetd.c 2009/01/22 00:35:28
|
|
@@ -38,6 +38,9 @@
|
|
int sockfd_read, sockfd_write, ptyfd;
|
|
int shell_pid;
|
|
|
|
+#ifdef TIOCPKT
|
|
+ int flowstate;
|
|
+#endif
|
|
/* two circular buffers */
|
|
/*char *buf1, *buf2;*/
|
|
/*#define TS_BUF1 ts->buf1*/
|
|
@@ -170,6 +173,9 @@
|
|
int fd, pid;
|
|
char tty_name[GETPTY_BUFSIZE];
|
|
struct tsession *ts = xzalloc(sizeof(struct tsession) + BUFSIZE * 2);
|
|
+#ifdef TIOCPKT
|
|
+ int on = 1;
|
|
+#endif
|
|
|
|
/*ts->buf1 = (char *)(ts + 1);*/
|
|
/*ts->buf2 = ts->buf1 + BUFSIZE;*/
|
|
@@ -180,6 +186,10 @@
|
|
maxfd = fd;
|
|
ts->ptyfd = fd;
|
|
ndelay_on(fd);
|
|
+#ifdef TIOCPKT
|
|
+ ioctl(fd, TIOCPKT, &on);
|
|
+ ts->flowstate = TIOCPKT_DOSTOP;
|
|
+#endif
|
|
#if ENABLE_FEATURE_TELNETD_STANDALONE
|
|
ts->sockfd_read = sock;
|
|
/* SO_KEEPALIVE by popular demand */
|
|
@@ -385,6 +395,16 @@
|
|
portnbr = 23,
|
|
};
|
|
#endif
|
|
+#ifdef TIOCPKT
|
|
+ int control;
|
|
+ static const char lflow_on[] ALIGN1 =
|
|
+ {IAC, SB, TELOPT_LFLOW, LFLOW_ON, IAC, SE};
|
|
+ static const char lflow_off[] ALIGN1 =
|
|
+ {IAC, SB, TELOPT_LFLOW, LFLOW_OFF, IAC, SE};
|
|
+# define RESERVED sizeof(lflow_on)
|
|
+#else
|
|
+# define RESERVED 0
|
|
+#endif
|
|
/* 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"),
|
|
@@ -475,7 +495,7 @@
|
|
FD_SET(ts->sockfd_read, &rdfdset);
|
|
if (ts->size2 > 0) /* can write to socket */
|
|
FD_SET(ts->sockfd_write, &wrfdset);
|
|
- if (ts->size2 < BUFSIZE) /* can read from pty */
|
|
+ if (ts->size2 < (BUFSIZE - RESERVED)) /* can read from pty */
|
|
FD_SET(ts->ptyfd, &rdfdset);
|
|
}
|
|
ts = next;
|
|
@@ -593,6 +613,52 @@
|
|
goto skip4;
|
|
goto kill_session;
|
|
}
|
|
+#ifdef TIOCPKT
|
|
+ control = TS_BUF2[ts->rdidx2];
|
|
+ if (--count > 0 && control == TIOCPKT_DATA) {
|
|
+ /*
|
|
+ * If we are in packet mode, and we have
|
|
+ * just read a chunk of actual data from
|
|
+ * the pty, then there is the TIOCPKT_DATA
|
|
+ * byte (zero) that we have got to remove
|
|
+ * somehow. If there were no chars in
|
|
+ * TS_BUF2 before we did this read, then
|
|
+ * we can optimize by just advancing wridx2.
|
|
+ * Otherwise we have to copy the new data down
|
|
+ * to close the gap (Could use readv() instead).
|
|
+ */
|
|
+ if (ts->size2 == 0)
|
|
+ ts->wridx2++;
|
|
+ else {
|
|
+ memmove(TS_BUF2 + ts->rdidx2,
|
|
+ TS_BUF2 + ts->rdidx2 + 1, count);
|
|
+ }
|
|
+ }
|
|
+
|
|
+ /*
|
|
+ * If the flow control state changed, notify
|
|
+ * the client. If "control" is not TIOCPKT_DATA,
|
|
+ * then there are no data bytes to worry about.
|
|
+ */
|
|
+ if ((control & (TIOCPKT_DOSTOP|TIOCPKT_NOSTOP)) != 0
|
|
+ && ts->flowstate != (control & TIOCPKT_DOSTOP)) {
|
|
+ const char *p = ts->flowstate ? lflow_off : lflow_on;
|
|
+
|
|
+ /*
|
|
+ * We know we have enough free slots available
|
|
+ * (see RESERVED) but they are not necessarily
|
|
+ * contiguous; we may have to wrap.
|
|
+ */
|
|
+ for (count = sizeof(lflow_on); count > 0; count--) {
|
|
+ TS_BUF2[ts->rdidx2++] = *p++;
|
|
+ if (ts->rdidx2 >= BUFSIZE)
|
|
+ ts->rdidx2 = 0;
|
|
+ ts->size2++;
|
|
+ }
|
|
+
|
|
+ ts->flowstate = control & TIOCPKT_DOSTOP;
|
|
+ }
|
|
+#endif /* TIOCPKT */
|
|
ts->size2 += count;
|
|
ts->rdidx2 += count;
|
|
if (ts->rdidx2 >= BUFSIZE) /* actually == BUFSIZE */
|
|
|
|
--Doug
|
|
_______________________________________________
|
|
busybox mailing list
|
|
busybox@busybox.net
|
|
http://lists.busybox.net/mailman/listinfo/busybox
|