[git commit] telnetd: Added support for AYT IAC command.

[Denys Vlasenko]

commit: https://git.busybox.net/busybox/commit/?id=93594b1197cf3ae1835eedebbebb2b40ea2a81f7
branch: https://git.busybox.net/busybox/commit/?id=refs/heads/master

Fixed a TODO in AYT IAC handling by replying back with a NOP.

Signed-off-by: Martin Lewis <martin.lewis.x84 at gmail.com>
Signed-off-by: Denys Vlasenko <vda.linux at googlemail.com>
---
 networking/telnetd.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/networking/telnetd.c b/networking/telnetd.c
index caef15181..bd60c8681 100644
--- a/networking/telnetd.c
+++ b/networking/telnetd.c
@@ -249,7 +249,7 @@ safe_write_to_pty_decode_iac(struct tsession *ts)
 	 * IAC SE  (240) End of subnegotiation. Treated as NOP.
 	 * IAC NOP (241) NOP. Supported.
 	 * IAC BRK (243) Break. Like serial line break. TODO via tcsendbreak()?
-	 * IAC AYT (246) Are you there. Send back evidence that AYT was seen. TODO (send NOP back)?
+	 * IAC AYT (246) Are you there.
 	 *  These don't look useful:
 	 * IAC DM  (242) Data mark. What is this?
 	 * IAC IP  (244) Suspend, interrupt or abort the process. (Ancient cousin of ^C).
@@ -277,6 +277,13 @@ safe_write_to_pty_decode_iac(struct tsession *ts)
 		rc = 2;
 		goto update_and_return;
 	}
+	if (buf[1] == AYT) {
+		/* Send back evidence that AYT was seen. */
+		buf[1] = NOP;
+		/*rc =*/ safe_write(ts->sockfd_write, buf, 2);
+		rc = 2;
+		goto update_and_return;
+	}
 	if (buf[1] >= 240 && buf[1] <= 249) {
 		/* NOP (241). Ignore (putty keepalive, etc) */
 		/* All other 2-byte commands also treated as NOPs here */