tls function skeleton

src/modem.rs

@@ -269,6 +269,16 @@ impl<UART: serial::Uart> Modem<UART> {
         Ok(())
     }
 
+    pub fn tls_connect(&mut self, addr: &str, port: u16) -> Result<()> {
+        let _ = self.tcp_connect(addr, port)?;
+
+        // ------------------------
+        // TLS handshake goes here.
+        // ------------------------
+
+        Ok(())
+    }
+
     pub fn tcp_set_quick_mode(&mut self, mode: bool) -> Result<()> {
         self.send_command(Command::tcp_set_quick_mode(mode))
             .map(|_| ())