From 4a7e5609f543c9363b3fba713d147123d3cf5c61 Mon Sep 17 00:00:00 2001
From: Michael Jumper <mike.jumper@guac-dev.org>
Date: Wed, 7 May 2014 15:30:48 -0700
Subject: [PATCH] GUAC-654: Implement local echo.

---
 src/protocols/telnet/client.c        |  1 +
 src/protocols/telnet/client.h        |  6 ++++++
 src/protocols/telnet/telnet_client.c | 21 ++++++++++++++++++---
 3 files changed, 25 insertions(+), 3 deletions(-)

diff --git a/src/protocols/telnet/client.c b/src/protocols/telnet/client.c
index 21ffe039..fce5cb82 100644
--- a/src/protocols/telnet/client.c
+++ b/src/protocols/telnet/client.c
@@ -85,6 +85,7 @@ int guac_client_init(guac_client* client, int argc, char** argv) {
     client_data->telnet = NULL;
     client_data->socket_fd = -1;
     client_data->naws_enabled = 0;
+    client_data->echo_enabled = 1;
 
     if (argc != TELNET_ARGS_COUNT) {
         guac_client_abort(client, GUAC_PROTOCOL_STATUS_SERVER_ERROR, "Wrong number of arguments");
diff --git a/src/protocols/telnet/client.h b/src/protocols/telnet/client.h
index da2455cf..227d0e56 100644
--- a/src/protocols/telnet/client.h
+++ b/src/protocols/telnet/client.h
@@ -75,6 +75,12 @@ typedef struct guac_telnet_client_data {
      */
     int naws_enabled;
 
+    /**
+     * Whether all user input should be automatically echoed to the
+     * terminal.
+     */
+    int echo_enabled;
+
     /**
      * The terminal which will render all output from the telnet client.
      */
diff --git a/src/protocols/telnet/telnet_client.c b/src/protocols/telnet/telnet_client.c
index a0933129..9ceff036 100644
--- a/src/protocols/telnet/telnet_client.c
+++ b/src/protocols/telnet/telnet_client.c
@@ -42,7 +42,7 @@
 #include <libtelnet.h>
 
 static const telnet_telopt_t __telnet_options[] = {
-    { TELNET_TELOPT_ECHO,      TELNET_WONT, TELNET_DONT },
+    { TELNET_TELOPT_ECHO,      TELNET_WONT, TELNET_DO   },
     { TELNET_TELOPT_TTYPE,     TELNET_WILL, TELNET_DONT },
     { TELNET_TELOPT_COMPRESS2, TELNET_WONT, TELNET_DO   },
     { TELNET_TELOPT_MSSP,      TELNET_WONT, TELNET_DO   },
@@ -89,7 +89,19 @@ static void __guac_telnet_event_handler(telnet_t* telnet, telnet_event_t* event,
                 guac_client_stop(client);
             break;
 
-        /* Feature enable */
+        /* Remote feature enabled */
+        case TELNET_EV_WILL:
+            if (event->neg.telopt == TELNET_TELOPT_ECHO)
+                client_data->echo_enabled = 0; /* Disable local echo, as remote will echo */
+            break;
+
+        /* Remote feature disabled */
+        case TELNET_EV_WONT:
+            if (event->neg.telopt == TELNET_TELOPT_ECHO)
+                client_data->echo_enabled = 1; /* Enable local echo, as remote won't echo */
+            break;
+
+        /* Local feature enable */
         case TELNET_EV_DO:
             if (event->neg.telopt == TELNET_TELOPT_NAWS) {
                 client_data->naws_enabled = 1;
@@ -131,8 +143,11 @@ static void* __guac_telnet_input_thread(void* data) {
     int bytes_read;
 
     /* Write all data read */
-    while ((bytes_read = guac_terminal_read_stdin(client_data->term, buffer, sizeof(buffer))) > 0)
+    while ((bytes_read = guac_terminal_read_stdin(client_data->term, buffer, sizeof(buffer))) > 0) {
         telnet_send(client_data->telnet, buffer, bytes_read);
+        if (client_data->echo_enabled)
+            guac_terminal_write_stdout(client_data->term, buffer, bytes_read);
+    }
 
     return NULL;