server: add some (currently unused) support for PTY's

coro/ssh/connection/interactive_session.py

@@ -57,35 +57,128 @@ class Interactive_Session_Client(Interactive_Session):
     def exec_command(self, command):
         self.send_channel_request('exec', EXEC_CHANNEL_REQUEST_PAYLOAD, (command,))
 
+# I think to do anything useful here we'll need full terminal emulation like http://liftoff.github.io/GateOne/Developer/terminal.html
+# from RFC4254 section 8
+pty_modes = {
+    0:     ('TTY_OP_END', "Indicates end of options."),
+    1:     ('VINTR', "Interrupt character; 255 if none.  Similarly for the other characters.  Not all of these characters are supported on all systems."),
+    2:     ('VQUIT', "The quit character (sends SIGQUIT signal on POSIX systems)."),
+    3:     ('VERASE', "Erase the character to left of the cursor."),
+    4:     ('VKILL', "Kill the current input line."),
+    5:     ('VEOF', "End-of-file character (sends EOF from the terminal)."),
+    6:     ('VEOL', "End-of-line character in addition to carriage return and/or linefeed."),
+    7:     ('VEOL2', "Additional end-of-line character."),
+    8:     ('VSTART', "Continues paused output (normally control-Q)."),
+    9:     ('VSTOP', "Pauses output (normally control-S)."),
+    10:    ('VSUSP', "Suspends the current program."),
+    11:    ('VDSUSP', "Another suspend character."),
+    12:    ('VREPRINT', "Reprints the current input line."),
+    13:    ('VWERASE', "Erases a word left of cursor."),
+    14:    ('VLNEXT', "Enter the next character typed literally, even if it is a special character"),
+    15:    ('VFLUSH', "Character to flush output."),
+    16:    ('VSWTCH', "Switch to a different shell layer."),
+    17:    ('VSTATUS', "Prints system status line (load, command, pid, etc)."),
+    18:    ('VDISCARD', "Toggles the flushing of terminal output."),
+    30:    ('IGNPAR', "The ignore parity flag.  The parameter SHOULD be 0 if this flag is FALSE, and 1 if it is TRUE."),
+    31:    ('PARMRK', "Mark parity and framing errors."),
+    32:    ('INPCK', "Enable checking of parity errors."),
+    33:    ('ISTRIP', "Strip 8th bit off characters."),
+    34:    ('INLCR', "Map NL into CR on input."),
+    35:    ('IGNCR', "Ignore CR on input."),
+    36:    ('ICRNL', "Map CR to NL on input."),
+    37:    ('IUCLC', "Translate uppercase characters to lowercase."),
+    38:    ('IXON', "Enable output flow control."),
+    39:    ('IXANY', "Any char will restart after stop."),
+    40:    ('IXOFF', "Enable input flow control."),
+    41:    ('IMAXBEL', "Ring bell on input queue full."),
+    50:    ('ISIG', "Enable signals INTR, QUIT, [D]SUSP."),
+    51:    ('ICANON', "Canonicalize input lines."),
+    52:    ('XCASE', "Enable input and output of uppercase characters by preceding their lowercase equivalents '\'."),
+    53:    ('ECHO', "Enable echoing."),
+    54:    ('ECHOE', "Visually erase chars."),
+    55:    ('ECHOK', "Kill character discards current line."),
+    56:    ('ECHONL', "Echo NL even if ECHO is off."),
+    57:    ('NOFLSH', "Don't flush after interrupt."),
+    58:    ('TOSTOP', "Stop background jobs from output."),
+    59:    ('IEXTEN', "Enable extensions."),
+    60:    ('ECHOCTL', "Echo control characters as ^(Char)."),
+    61:    ('ECHOKE', "Visual erase for line kill."),
+    62:    ('PENDIN', "Retype pending input."),
+    70:    ('OPOST', "Enable output processing."),
+    71:    ('OLCUC', "Convert lowercase to uppercase."),
+    72:    ('ONLCR', "Map NL to CR-NL."),
+    73:    ('OCRNL', "Translate carriage return to newline (output)."),
+    74:    ('ONOCR', "Translate newline to carriage return-newline (output)."),
+    75:    ('ONLRET', "Newline performs a carriage return (output)."),
+    90:    ('CS7', "7 bit mode."),
+    91:    ('CS8', "8 bit mode."),
+    92:    ('PARENB', "Parity enable."),
+    93:    ('PARODD', "Odd parity, else even."),
+    128:   ('TTY_OP_ISPEED', "Specifies the input baud rate in bits per second."),
+    129:   ('TTY_OP_OSPEED', "Specifies the output baud rate in bits per second."),
+    }
+
+class PTY:
+    def __init__ (self, settings):
+        self.term, self.width_char, self.height_char, self.width_pixels, self.height_pixels, self.modes = settings
+        #self.unpack_modes()
+
+    def unpack_modes (self):
+        import struct
+        i = 0
+        modes = self.modes
+        while i < len (modes):
+            opcode = ord (modes[i])
+            i += 1
+            if opcode >= 160:
+                break
+            elif pty_modes.has_key (opcode):
+                name, description = pty_modes[opcode]
+                value, = struct.unpack ('>L', modes[i:i+4])
+                setattr (self, name, value)
+                i += 4
+                #W ('PTY setting: %r = %r\n' % (name, value))
+            else:
+                #W ('unknown PTY setting: %r = %r\n' % (opcode, struct.unpack ('>L', modes[i:i+4])))
+                i += 4
+
 class Interactive_Session_Server(Interactive_Session):
 
     def handle_request(self, request_type, want_reply, type_specific_packet_data):
-        W ('interactive_session_server: handle_request %r %r %r\n' % (request_type, want_reply, type_specific_packet_data))
+        #W ('interactive_session_server: handle_request %r %r %r\n' % (request_type, want_reply, type_specific_packet_data))
         if self.request_handlers.has_key(request_type):
             self.request_handlers[request_type] (self, want_reply, type_specific_packet_data)
-        else:
-            if want_reply:
-                packet = ssh_packet.pack_payload(SSH_MSG_CHANNEL_FAILURE_PAYLOAD, (self.remote_channel.channel_id,))
-                self.transport.send_packet(packet)
+        elif want_reply:
+            packet = ssh_packet.pack_payload(SSH_MSG_CHANNEL_FAILURE_PAYLOAD, (self.remote_channel.channel_id,))
+            self.transport.send_packet(packet)
+
+    # by default, refuse PTY requests, a lot of terminal smarts are needed to do it right.
+    accept_pty = False
 
     def handle_pty_request(self, want_reply, type_specific_packet_data):
-        term, width_char, height_char, width_pixels, height_pixels, modes = ssh_packet.unpack_payload(PTY_CHANNEL_REQUEST_PAYLOAD, type_specific_packet_data)
-        # XXX do some PTY crap here
-        self.send_channel_request_failure()
+        self.pty = PTY (ssh_packet.unpack_payload(PTY_CHANNEL_REQUEST_PAYLOAD, type_specific_packet_data))
+        if want_reply:
+            if self.accept_pty:
+                self.send_channel_request_success()
+            else:
+                self.send_channel_request_failure()
 
     def handle_x11_request(self, want_reply, type_specific_packet_data):
         single_connection, auth_protocol, auth_cookie, screen_number = ssh_packet.unpack_payload(X11_CHANNEL_REQUEST_PAYLOAD, type_specific_packet_data)
         # XXX fantasize about doing X11 forwarding here?  I think not.
-        self.send_channel_request_failure()
+        if want_reply:
+            self.send_channel_request_failure()
 
     def handle_shell_request(self, want_reply, type_specific_packet_data):
         # XXX whatever, sure, it worked.
-        self.send_channel_request_success()
+        if want_reply:
+            self.send_channel_request_success()
         
     request_handlers = {
         'pty-req':  handle_pty_request,
         'x11-req':  handle_x11_request,
         'shell' : handle_shell_request,
+        # env :
         # exec : 
         # subsystem : 
     }