From c7a935dc1af219b0feb79b571a9e9bd2fe7fae3a Mon Sep 17 00:00:00 2001
From: Huang Qi <huangqi3@xiaomi.com>
Date: Wed, 5 Apr 2023 20:25:19 +0800
Subject: [PATCH] drivers/telnet: Implement part of termios

Implement local mode control (ECHO only) for telnet, this allow application to disable ECHO of telnet, it's useful to input password during shell login and other case.

Signed-off-by: Huang Qi <huangqi3@xiaomi.com>
---
 drivers/net/telnet.c | 61 +++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 57 insertions(+), 4 deletions(-)

diff --git a/drivers/net/telnet.c b/drivers/net/telnet.c
index 1a77e29d00..6b3633015e 100644
--- a/drivers/net/telnet.c
+++ b/drivers/net/telnet.c
@@ -30,6 +30,7 @@
 #include <poll.h>
 #include <errno.h>
 #include <debug.h>
+#include <termios.h>
 
 #include <nuttx/kmalloc.h>
 #include <nuttx/kthread.h>
@@ -125,6 +126,7 @@ struct telnet_dev_s
 #ifdef HAVE_SIGNALS
   pid_t             td_pid;
 #endif
+  tcflag_t          td_lflag;     /* Local modes */
   FAR struct socket td_psock;     /* A clone of the internal socket structure */
   char td_rxbuffer[CONFIG_TELNET_RXBUFFER_SIZE];
   char td_txbuffer[CONFIG_TELNET_TXBUFFER_SIZE];
@@ -414,11 +416,15 @@ static ssize_t telnet_receive(FAR struct telnet_dev_s *priv,
 
           case STATE_DO:
 
-            /* FIXME: Handle ECHO and SGA setting here
-             * Used to disable ECHO password in login nsh via telnet
-             */
+            if ((priv->td_lflag & ECHO) != 0 && ch == TELNET_ECHO)
+              {
+                telnet_sendopt(priv, TELNET_WONT, ch);
+              }
+            else
+              {
+                telnet_sendopt(priv, TELNET_WILL, ch);
+              }
 
-            telnet_sendopt(priv, TELNET_WONT, ch);
             priv->td_state = STATE_NORMAL;
             break;
 
@@ -963,6 +969,10 @@ static int telnet_session(FAR struct telnet_session_s *session)
       goto errout_with_lock;
     }
 
+  /* Setting terminal attributes */
+
+  priv->td_lflag = ECHO;
+
   /* Register the driver */
 
   ret = register_driver(session->ts_devpath, &g_telnet_fops, 0666, priv);
@@ -1027,6 +1037,7 @@ static int telnet_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
 {
   FAR struct inode *inode = filep->f_inode;
   FAR struct telnet_dev_s *priv = inode->i_private;
+  FAR struct termios *termiosp;
   int ret = OK;
 
   switch (cmd)
@@ -1064,6 +1075,48 @@ static int telnet_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
       break;
 #endif
 
+    /* Handle TERMIOS command */
+
+    case TCGETS:
+      {
+        termiosp = (FAR struct termios *)((uintptr_t)arg);
+        DEBUGASSERT(termiosp != NULL);
+
+        cfmakeraw(termiosp);
+
+        termiosp->c_lflag = priv->td_lflag;
+      }
+      break;
+
+    case TCSETS:
+      {
+        termiosp = (FAR struct termios *)((uintptr_t)arg);
+        DEBUGASSERT(termiosp != NULL);
+
+        /* Save the termios settings */
+
+        priv->td_lflag = termiosp->c_lflag;
+
+        if ((priv->td_lflag & ECHO) != 0)
+          {
+            /* If ECHO is set, then we need to send the won't echo option
+             * to the client, let the client do echo to emulate
+             * the behavior of a real terminal.
+             */
+
+            telnet_sendopt(priv, TELNET_WONT, TELNET_ECHO);
+          }
+        else
+          {
+            /* Otherwise, we need to send the will echo option to the
+             * client, let the client don't echo to disable the echo.
+             */
+
+            telnet_sendopt(priv, TELNET_WILL, TELNET_ECHO);
+          }
+      }
+      break;
+
     default:
       ret = psock_ioctl(&priv->td_psock, cmd, arg);
       break;