telnetd: Added support for AYT IAC command.

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

Signed-off-by: Martin Lewis <martin.lewis.x84@gmail.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

diff --git a/networking/telnetd.c b/networking/telnetd.c
index caef151811c846058249a0edeab9a24b609ed2ad..bd60c8681b8ffed0c0de6847cf878e59d8083b25 100644 (file)
--- 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 */