mirror of
https://github.com/topjohnwu/ndk-busybox.git
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telnetd: do not advertise TELNET_LFLOW, we do not support
it properly.
This commit is contained in:
Denis Vlasenko
parent
04158e0459
commit
d814c98692
@ -35,8 +35,8 @@
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/* Structure that describes a session */
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struct tsession {
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struct tsession *next;
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pid_t shell_pid;
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int sockfd_read, sockfd_write, ptyfd;
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int shell_pid;
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/* two circular buffers */
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/*char *buf1, *buf2;*/
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@ -247,7 +247,8 @@ make_new_session(
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static const char iacs_to_send[] ALIGN1 = {
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IAC, DO, TELOPT_ECHO,
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IAC, DO, TELOPT_NAWS,
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IAC, DO, TELOPT_LFLOW,
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/* This requires telnetd.ctrlSQ.patch (incomplete) */
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/* IAC, DO, TELOPT_LFLOW, */
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IAC, WILL, TELOPT_ECHO,
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IAC, WILL, TELOPT_SGA
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};
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@ -284,13 +285,13 @@ make_new_session(
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/* Child */
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/* Careful - we are after vfork! */
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/* make new session and process group */
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setsid();
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/* Restore default signal handling */
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/* Restore default signal handling ASAP */
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bb_signals((1 << SIGCHLD) + (1 << SIGPIPE), SIG_DFL);
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/* open the child's side of the tty. */
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/* Make new session and process group */
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setsid();
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/* Open the child's side of the tty. */
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/* NB: setsid() disconnects from any previous ctty's. Therefore
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* we must open child's side of the tty AFTER setsid! */
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close(0);
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@ -360,7 +361,7 @@ free_session(struct tsession *ts)
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* doesn't send SIGKILL. When we close ptyfd,
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* kernel sends SIGHUP to processes having slave side opened. */
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kill(ts->shell_pid, SIGKILL);
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wait4(ts->shell_pid, NULL, 0, NULL);
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waitpid(ts->shell_pid, NULL, 0);
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#endif
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close(ts->ptyfd);
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close(ts->sockfd_read);
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175
networking/telnetd.ctrlSQ.patch
Normal file
175
networking/telnetd.ctrlSQ.patch
Normal file
@ -0,0 +1,175 @@
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From: "Doug Graham" <dgraham@nortel.com>
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Date: 2009-01-22 07:20
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Hello,
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Busybox's telnetd does not disable local (client-side) flow control
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properly. It does not put the pty into packet mode and then notify the
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client whenever flow control is disabled by an application running under
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its control. The result is that ^S/^Q are not passed through to the
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application, which is painful when the application is an emacs variant.
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I suppose that support for this might be considered bloat, but the
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included patch only adds about 200 bytes of text to x86 busybox and 300
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bytes to mipsel busybox. Please consider applying.
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=============================
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NB: the patch doesn't work as-is because we now have iac_safe_write()
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which quotes IACs on output.
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=============================
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Docs:
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The following ioctl(2) calls apply only to pseudo terminals:
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TIOCSTOP Stops output to a terminal (e.g. like typing ^S). Takes no parameter.
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TIOCSTART Restarts output (stopped by TIOCSTOP or by typing ^S). Takes no parameter.
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TIOCPKT Enable/disable packet mode. When applied to the master side of a pseudo terminal, each
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subsequent read(2) from the terminal will return data written on the slave part of the pseudo terminal preceded by a
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zero byte (symbolically defined as TIOCPKT_DATA), or a single byte reflecting control status information.
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In the latter case, the byte is an inclusive-or of zero or more of the bits:
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TIOCPKT_FLUSHREAD whenever the read queue for the terminal is flushed.
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TIOCPKT_FLUSHWRITE whenever the write queue for the terminal is flushed.
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TIOCPKT_STOP whenever output to the terminal is stopped a la ^S.
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TIOCPKT_START whenever output to the terminal is restarted.
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TIOCPKT_DOSTOP whenever t_stopc is ^S and t_startc is ^Q.
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TIOCPKT_NOSTOP whenever the start and stop characters are not ^S/^Q.
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While this mode is in use, the presence of control status information to be read from the master side may be detected
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by a select(2) for exceptional conditions.
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This mode is used by rlogin(1) and rlogind(8) to implement a remote-echoed, locally ^S/^Q flow-controlled remote login
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with proper back-flushing of output; it can be used by other similar programs.
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TIOCUCNTL Enable/disable a mode that allows a small number of simple user ioctl(2) commands to be passed through
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the pseudo-terminal, using a protocol similar to that of TIOCPKT. The TIOCUCNTL and TIOCPKT modes are mutually
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exclusive. This mode is enabled from the master side of a pseudo terminal. Each subsequent read(2) from the master side
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will return data written on the slave part of the pseudo terminal preceded by a zero byte, or a single byte reflecting a
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user control operation on the slave side. A user control command consists of a special ioctl(2) operation with no data;
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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
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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
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for the existence of this facility. As with TIOCPKT mode, command operations may be detected with a select(2) for
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exceptional conditions.
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--- busybox-1.13.2/networking/telnetd.c 2009/01/21 20:02:39 1.1
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+++ busybox-1.13.2/networking/telnetd.c 2009/01/22 00:35:28
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@@ -38,6 +38,9 @@
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int sockfd_read, sockfd_write, ptyfd;
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int shell_pid;
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+#ifdef TIOCPKT
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+ int flowstate;
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+#endif
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/* two circular buffers */
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/*char *buf1, *buf2;*/
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/*#define TS_BUF1 ts->buf1*/
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@@ -170,6 +173,9 @@
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int fd, pid;
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char tty_name[GETPTY_BUFSIZE];
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struct tsession *ts = xzalloc(sizeof(struct tsession) + BUFSIZE * 2);
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+#ifdef TIOCPKT
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+ int on = 1;
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+#endif
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/*ts->buf1 = (char *)(ts + 1);*/
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/*ts->buf2 = ts->buf1 + BUFSIZE;*/
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@@ -180,6 +186,10 @@
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maxfd = fd;
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ts->ptyfd = fd;
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ndelay_on(fd);
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+#ifdef TIOCPKT
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+ ioctl(fd, TIOCPKT, &on);
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+ ts->flowstate = TIOCPKT_DOSTOP;
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+#endif
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#if ENABLE_FEATURE_TELNETD_STANDALONE
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ts->sockfd_read = sock;
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/* SO_KEEPALIVE by popular demand */
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@@ -385,6 +395,16 @@
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portnbr = 23,
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};
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#endif
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+#ifdef TIOCPKT
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+ int control;
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+ static const char lflow_on[] =
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+ {IAC, SB, TELOPT_LFLOW, LFLOW_ON, IAC, SE};
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+ static const char lflow_off[] =
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+ {IAC, SB, TELOPT_LFLOW, LFLOW_OFF, IAC, SE};
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+# define RESERVED sizeof(lflow_on)
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+#else
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+# define RESERVED 0
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+#endif
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/* Even if !STANDALONE, we accept (and ignore) -i, thus people
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* don't need to guess whether it's ok to pass -i to us */
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opt = getopt32(argv, "f:l:Ki" USE_FEATURE_TELNETD_STANDALONE("p:b:F"),
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@@ -475,7 +495,7 @@
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FD_SET(ts->sockfd_read, &rdfdset);
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if (ts->size2 > 0) /* can write to socket */
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FD_SET(ts->sockfd_write, &wrfdset);
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- if (ts->size2 < BUFSIZE) /* can read from pty */
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+ if (ts->size2 < (BUFSIZE - RESERVED)) /* can read from pty */
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FD_SET(ts->ptyfd, &rdfdset);
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}
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ts = next;
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@@ -593,6 +613,52 @@
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goto skip4;
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goto kill_session;
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}
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+#ifdef TIOCPKT
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+ control = TS_BUF2[ts->rdidx2];
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+ if (--count > 0 && control == TIOCPKT_DATA) {
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+ /*
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+ * If we are in packet mode, and we have
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+ * just read a chunk of actual data from
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+ * the pty, then there is the TIOCPKT_DATA
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+ * byte (zero) that we have got to remove
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+ * somehow. If there were no chars in
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+ * TS_BUF2 before we did this read, then
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+ * we can optimize by just advancing wridx2.
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+ * Otherwise we have to copy the new data down
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+ * to close the gap (Could use readv() instead).
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+ */
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+ if (ts->size2 == 0)
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+ ts->wridx2++;
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+ else {
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+ memmove(TS_BUF2 + ts->rdidx2,
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+ TS_BUF2 + ts->rdidx2 + 1, count);
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+ }
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+ }
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+
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+ /*
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+ * If the flow control state changed, notify
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+ * the client. If "control" is not TIOCPKT_DATA,
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+ * then there are no data bytes to worry about.
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+ */
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+ if ((control & (TIOCPKT_DOSTOP|TIOCPKT_NOSTOP)) != 0
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+ && ts->flowstate != (control & TIOCPKT_DOSTOP)) {
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+ const char *p = ts->flowstate ? lflow_off : lflow_on;
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+
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+ /*
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+ * We know we have enough free slots available
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+ * (see RESERVED) but they are not necessarily
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+ * contiguous; we may have to wrap.
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+ */
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+ for (count = sizeof(lflow_on); count > 0; count--) {
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+ TS_BUF2[ts->rdidx2++] = *p++;
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+ if (ts->rdidx2 >= BUFSIZE)
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+ ts->rdidx2 = 0;
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+ ts->size2++;
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+ }
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+
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+ ts->flowstate = control & TIOCPKT_DOSTOP;
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+ }
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+#endif /* TIOCPKT */
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ts->size2 += count;
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ts->rdidx2 += count;
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if (ts->rdidx2 >= BUFSIZE) /* actually == BUFSIZE */
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--Doug
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_______________________________________________
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busybox mailing list
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busybox@busybox.net
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http://lists.busybox.net/mailman/listinfo/busybox
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