GUAC-748: Add username parameter to telnet. Pass username via NEW-ENVIRONMENT telnet option.

src/protocols/telnet/client.c

@@ -45,6 +45,7 @@
 const char* GUAC_CLIENT_ARGS[] = {
     "hostname",
     "port",
+    "username",
     "font-name",
     "font-size",
     NULL
@@ -62,6 +63,11 @@ enum __TELNET_ARGS_IDX {
      */
     IDX_PORT,
 
+    /**
+     * The name of the user to login as. Optional.
+     */
+    IDX_USERNAME,
+
     /**
      * The name of the font to use within the terminal.
      */
@@ -100,6 +106,7 @@ int guac_client_init(guac_client* client, int argc, char** argv) {
 
     /* Read parameters */
     strcpy(client_data->hostname,  argv[IDX_HOSTNAME]);
+    strcpy(client_data->username,  argv[IDX_USERNAME]);
 
     /* Read port */
     if (argv[IDX_PORT][0] != 0)

src/protocols/telnet/client.h

@@ -44,6 +44,11 @@ typedef struct guac_telnet_client_data {
      */
     char port[64];
 
+    /**
+     * The name of the user to login as.
+     */
+    char username[1024];
+
     /**
      * The name of the font to use for display rendering.
      */

src/protocols/telnet/telnet_client.c

@@ -44,11 +44,12 @@
  * negotiation by telnet_init(), part of libtelnet.
  */
 static const telnet_telopt_t __telnet_options[] = {
-    { 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   },
-    { TELNET_TELOPT_NAWS,      TELNET_WILL, 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   },
+    { TELNET_TELOPT_NAWS,        TELNET_WILL, TELNET_DONT },
+    { TELNET_TELOPT_NEW_ENVIRON, TELNET_WILL, TELNET_DONT },
     { -1, 0, 0 }
 };
 
@@ -132,6 +133,15 @@ static void __guac_telnet_event_handler(telnet_t* telnet, telnet_event_t* event,
                 telnet_ttype_is(client_data->telnet, "linux");
             break;
 
+        /* Environment request */
+        case TELNET_EV_ENVIRON:
+
+            /* Only send USER if entire environment was requested */
+            if (event->environ.size == 0)
+                guac_telnet_send_user(telnet, client_data->username);
+
+            break;
+
         /* Connection warnings */
         case TELNET_EV_WARNING:
             guac_client_log_info(client, "%s", event->error.msg);
@@ -293,6 +303,16 @@ static void __guac_telnet_send_uint16(telnet_t* telnet, uint16_t value) {
 
 }
 
+/**
+ * Sends an 8-bit value over the given telnet connection.
+ *
+ * @param telnet The telnet connection to use.
+ * @param value The value to send.
+ */
+static void __guac_telnet_send_uint8(telnet_t* telnet, uint8_t value) {
+    telnet_send(telnet, (char*) (&value), 1);
+}
+
 void guac_telnet_send_naws(telnet_t* telnet, uint16_t width, uint16_t height) {
     telnet_begin_sb(telnet, TELNET_TELOPT_NAWS);
     __guac_telnet_send_uint16(telnet, width);
@@ -300,6 +320,25 @@ void guac_telnet_send_naws(telnet_t* telnet, uint16_t width, uint16_t height) {
     telnet_finish_sb(telnet);
 }
 
+void guac_telnet_send_user(telnet_t* telnet, const char* username) {
+
+    /* IAC SB NEW-ENVIRON IS */
+    telnet_begin_sb(telnet, TELNET_TELOPT_NEW_ENVIRON);
+    __guac_telnet_send_uint8(telnet, TELNET_ENVIRON_IS);
+
+    /* VAR "USER" */
+    __guac_telnet_send_uint8(telnet, TELNET_ENVIRON_VAR);
+    telnet_send(telnet, "USER", 4);
+
+    /* VALUE username */
+    __guac_telnet_send_uint8(telnet, TELNET_ENVIRON_VALUE);
+    telnet_send(telnet, username, strlen(username));
+
+    /* IAC SE */
+    telnet_finish_sb(telnet);
+
+}
+
 /**
  * Waits for data on the given file descriptor for up to one second. The
  * return value is identical to that of select(): 0 on timeout, < 0 on

src/protocols/telnet/telnet_client.h

@@ -40,5 +40,11 @@ void* guac_telnet_client_thread(void* data);
  */
 void guac_telnet_send_naws(telnet_t* telnet, uint16_t width, uint16_t height);
 
+/**
+ * Sends the given username by setting the remote USER environment variable
+ * using the telnet NEW-ENVIRON option.
+ */
+void guac_telnet_send_user(telnet_t* telnet, const char* username);
+
 #endif