Special handling for TCP clients in the shell

libraries/Terminal/Shell.cpp

@@ -133,6 +133,7 @@ Shell::Shell()
     , historyPosn(0)
     , prom("> ")
     , hideChars(false)
+    , isClient(false)
 {
 }
 
@@ -152,7 +153,7 @@ Shell::~Shell()
  * \param maxHistory The number of commands to allocate in the history
  * stack for scrolling back through using Up/Down arrow keys.
  * \param mode The terminal mode to operate in, Terminal::Serial or
- * Terminal::Telnet.
+ * Terminal::Telnet.  Default is Terminal::Serial.
  * \return Returns true if the shell was initialized, or false if there
  * is insufficient memory for the history stack.
  *
@@ -169,6 +170,44 @@ Shell::~Shell()
  * \sa end(), setPrompt()
  */
 bool Shell::begin(Stream &stream, size_t maxHistory, Terminal::Mode mode)
+{
+    if (!beginShell(stream, maxHistory, mode))
+        return false;
+    isClient = false;
+    return true;
+}
+
+/**
+ * \brief Begin shell handling on a connected TCP client.
+ *
+ * \param client The client to apply the shell to.  This must be a
+ * connected TCP client.
+ * \param maxHistory The number of commands to allocate in the history
+ * stack for scrolling back through using Up/Down arrow keys.
+ * \param mode The terminal mode to operate in, Terminal::Serial or
+ * Terminal::Telnet.  Default is Terminal::Telnet.
+ * \return Returns true if the shell was initialized, or false if there
+ * is insufficient memory for the history stack.
+ *
+ * This override is provided as a convenience for starting a shell on a
+ * TCP connection.  This function also modifies the behaviour of the
+ * builtin "exit" command to forcibly stop the TCP connection rather
+ * than returning to the login prompt.
+ *
+ * \sa end(), setPrompt()
+ */
+bool Shell::begin(Client &client, size_t maxHistory, Terminal::Mode mode)
+{
+    if (!beginShell(client, maxHistory, mode))
+        return false;
+    isClient = true;
+    return true;
+}
+
+/**
+ * \brief Internal implementation of begin().
+ */
+bool Shell::beginShell(Stream &stream, size_t maxHistory, Terminal::Mode mode)
 {
     // Initialize the Terminal base class with the underlying stream.
     Terminal::begin(stream, mode);
@@ -217,6 +256,7 @@ void Shell::end()
     historyWrite = 0;
     historyPosn = 0;
     hideChars = false;
+    isClient = false;
 }
 
 /** @cond */
@@ -236,6 +276,12 @@ static char const builtin_cmd_help_alt[] PROGMEM = "?";
  */
 void Shell::loop()
 {
+    // If the stream is a TCP client, then check for disconnection.
+    if (isClient && !((Client *)stream())->connected()) {
+        end();
+        return;
+    }
+
     // Read the next key and bail out if none.  We only process a single
     // key each time we enter this function to prevent other tasks in the
     // system from becoming starved of time resources if the bytes are
@@ -499,6 +545,21 @@ void Shell::help()
     }
 }
 
+/**
+ * \brief Exit from the shell back to the login prompt.
+ *
+ * If the underlying stream is a TCP client, then this function will
+ * stop the client, causing disconnection.
+ */
+void Shell::exit()
+{
+    Stream *stream = this->stream();
+    if (isClient) {
+        end();
+        ((Client *)stream)->stop();
+    }
+}
+
 /**
  * \brief Executes the command in the buffer.
  */
@@ -538,6 +599,8 @@ void Shell::execute()
             if (!strcmp_P(argv0, builtin_cmd_help) ||
                     !strcmp_P(argv0, builtin_cmd_help_alt)) {
                 help();
+            } else if (!strcmp_P(argv0, builtin_cmd_exit)) {
+                exit();
             } else {
                 static char const unknown_cmd[] PROGMEM = "Unknown command: ";
                 writeProgMem(unknown_cmd);

libraries/Terminal/Shell.h

@@ -24,6 +24,7 @@
 #define SHELL_h
 
 #include "Terminal.h"
+#include <Client.h>
 
 class Shell;
 class ShellArguments;
@@ -65,6 +66,7 @@ public:
     virtual ~Shell();
 
     bool begin(Stream &stream, size_t maxHistory = 0, Terminal::Mode mode = Serial);
+    bool begin(Client &client, size_t maxHistory = 0, Terminal::Mode mode = Telnet);
     void end();
 
     void loop();
@@ -78,6 +80,7 @@ public:
     void setHideCharacters(bool hide);
 
     void help();
+    void exit();
 
 private:
     char buffer[SHELL_MAX_CMD_LEN];
@@ -88,11 +91,13 @@ private:
     size_t historyPosn;
     const char *prom;
     bool hideChars;
+    bool isClient;
 
     // Disable copy constructor and operator=().
     Shell(const Shell &other) {}
     Shell &operator=(const Shell &) { return *this; }
 
+    bool beginShell(Stream &stream, size_t maxHistory, Terminal::Mode mode);
     void execute();
     bool execute(const ShellArguments &argv);
     void executeBuiltin(const char *cmd);

libraries/Terminal/Terminal.cpp

@@ -178,7 +178,7 @@ Terminal::~Terminal()
  * will be interpreted.  This is useful if the underlying \a stream is a TCP
  * connection on port 23.  The mode operates as a telnet server.
  *
- * \sa end(), mode()
+ * \sa end(), stream(), mode()
  */
 void Terminal::begin(Stream &stream, Mode mode)
 {
@@ -200,6 +200,14 @@ void Terminal::end()
     _stream = 0;
 }
 
+/**
+ * \fn Stream *Terminal::stream() const
+ * \brief Returns a pointer to the underlying Stream, or NULL if the
+ * stream has not been set with begin() yet.
+ *
+ * \sa begin()
+ */
+
 /**
  * \fn Terminal::Mode Terminal::mode() const
  * \brief Returns the mode this terminal is operating in, Serial or Telnet.

libraries/Terminal/Terminal.h

@@ -48,6 +48,7 @@ public:
     void begin(Stream &stream, Mode mode = Serial);
     void end();
 
+    Stream *stream() const { return _stream; }
     Terminal::Mode mode() const { return (Terminal::Mode)mod; }
 
     virtual int available();

libraries/Terminal/examples/TelnetServer/TelnetServer.ino

@@ -29,13 +29,7 @@ void cmdLed(Shell &shell, int argc, const ShellArguments &argv)
         digitalWrite(ledPin, LOW);
 }
 
-void cmdExit(Shell &shell, int argc, const ShellArguments &argv)
-{
-    client.stop();
-}
-
 ShellCommand(led, "Turns the status LED on or off", cmdLed);
-ShellCommand(exit, "Exit and log out", cmdExit);
 
 void setup()
 {
@@ -72,7 +66,7 @@ void loop()
         client = server.available();
         if (client) {
             haveClient = true;
-            shell.begin(client, 5, Terminal::Telnet);
+            shell.begin(client, 5);
         }
     } else if (!client.connected()) {
         // The current client has been disconnected.  Shut down the shell.