From 38492576bc5915adec990f08a6f70cbcfa97a418 Mon Sep 17 00:00:00 2001
From: Benjamin Valentin <benjamin.valentin@ml-pa.com>
Date: Fri, 2 Feb 2024 12:10:24 +0100
Subject: [PATCH] sys/net/telnet: disable local echo

---
 sys/net/application_layer/telnet/telnet_server.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/sys/net/application_layer/telnet/telnet_server.c b/sys/net/application_layer/telnet/telnet_server.c
index c167a0a053f4..6ab40bb677a4 100644
--- a/sys/net/application_layer/telnet/telnet_server.c
+++ b/sys/net/application_layer/telnet/telnet_server.c
@@ -195,6 +195,17 @@ static void _process_cmd(uint8_t cmd, uint8_t option)
     }
 }
 
+static void _send_opts(void)
+{
+    if (IS_USED(MODULE_STDIO_TELNET)) {
+        /* RIOT will echo stdio, disable local echo */
+        const uint8_t opt_echo[] = {
+            TELNET_CMD_IAC, TELNET_CMD_WILL, TELNET_OPT_ECHO
+        };
+        _write_buffer(opt_echo, sizeof(opt_echo));
+    }
+}
+
 static void *telnet_thread(void *arg)
 {
     (void)arg;
@@ -210,6 +221,7 @@ static void *telnet_thread(void *arg)
 
         DEBUG("connected\n");
         _connected();
+        _send_opts();
 
         bool is_cmd = false;
         uint8_t is_option = 0;