From 97707a9831d1b435b32d36a6cd24251dfefb4c5f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?David=20Hrdli=C4=8Dka?=
 <13226155+dhrdlicka@users.noreply.github.com>
Date: Sun, 23 Mar 2025 16:18:48 +0100
Subject: [PATCH] net_modem: fix response to unrecognized will/wont telnet
 commands

---
 src/network/net_modem.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/src/network/net_modem.c b/src/network/net_modem.c
index a8eab4290..af97a16db 100644
--- a/src/network/net_modem.c
+++ b/src/network/net_modem.c
@@ -1177,9 +1177,15 @@ modem_process_telnet(modem_t *modem, uint8_t *data, uint32_t size)
         uint8_t c = data[i];
         if (modem->telClient.inIAC) {
             if (modem->telClient.recCommand) {
+                modem_log("modem_process_telnet: received command %i, option %i\n", modem->telClient.command, c);
+
                 if ((c != 0) && (c != 1) && (c != 3)) {
-                    if (modem->telClient.command > 250) {
-                        /* Reject anything we don't recognize */
+                    /* Reject anything we don't recognize */
+                    if (modem->telClient.command == 251 || modem->telClient.command == 252) {
+                        modem_data_mode_process_byte(modem, 0xff);
+                        modem_data_mode_process_byte(modem, 254);
+                        modem_data_mode_process_byte(modem, c); /* Don't do crap! */
+                    } else if (modem->telClient.command == 253 || modem->telClient.command == 254) {
                         modem_data_mode_process_byte(modem, 0xff);
                         modem_data_mode_process_byte(modem, 252);
                         modem_data_mode_process_byte(modem, c); /* We won't do crap! */