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>

1 files changed, 8 insertions, 1 deletions

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 */