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telnetd: Added support for AYT IAC command.

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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>
This commit is contained in:
Martin Lewis
2019-04-04 13:29:32 +02:00
committed by Denys Vlasenko
parent 2b6282117f
commit 93594b1197
1 changed files with 8 additions and 1 deletions
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9
networking/telnetd.c
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@@ -249,7 +249,7 @@ safe_write_to_pty_decode_iac(struct tsession *ts)
* IAC SE (240) End of subnegotiation. Treated as NOP. * IAC SE (240) End of subnegotiation. Treated as NOP.
* IAC NOP (241) NOP. Supported. * IAC NOP (241) NOP. Supported.
* IAC BRK (243) Break. Like serial line break. TODO via tcsendbreak()? * 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: * These don't look useful:
* IAC DM (242) Data mark. What is this? * IAC DM (242) Data mark. What is this?
* IAC IP (244) Suspend, interrupt or abort the process. (Ancient cousin of ^C). * 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; rc = 2;
goto update_and_return; 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) { if (buf[1] >= 240 && buf[1] <= 249) {
/* NOP (241). Ignore (putty keepalive, etc) */ /* NOP (241). Ignore (putty keepalive, etc) */
/* All other 2-byte commands also treated as NOPs here */ /* All other 2-byte commands also treated as NOPs here */