New --console option

re6st/cli/node.py

@@ -56,6 +56,11 @@ def getConfig():
         help="Exit after configuration parsing. Status code is the"
              " result of the given Python expression. For example:\n"
              "  main_interface != 'eth0'")
+    _('--console', metavar='SOCK',
+        help="Socket path to Python console that can be used to inspect or"
+             " patch this process. Use:\n"
+             "   socat - UNIX:<SOCK>\n"
+             "to access it.")
 
     _ = parser.add_argument_group('routing').add_argument
     _('-B', dest='babel_args', metavar='ARG', action='append', default=[],
@@ -389,10 +394,23 @@ def main():
                                   tunnel_manager.killAll)
             except AttributeError:
                 pass
+            if config.console:
+                from re6st.debug import Console
+                def console(socket, frame=sys._getframe()):
+                    try:
+                        import pdb; pdb.Pdb(stdin=socket,
+                                            stdout=socket).set_trace()
+                        frame.f_locals # main() locals
+                    finally:
+                        socket.close()
+                console = Console(config.console, console)
+                cleanup.append(console.close)
 
             # main loop
             exit.release()
             select_list = [forwarder.select] if forwarder else []
+            if config.console:
+                select_list.append(console.select)
             select_list += tunnel_manager.select, utils.select
             while True:
                 args = R.copy(), {}, []

re6st/debug.py

+import errno, os, socket, stat, threading
+
+
+class Socket(object):
+
+    def __init__(self, socket):
+        # In case that the default timeout is not None.
+        socket.settimeout(None)
+        self._socket = socket
+        self._buf = ''
+
+    def close(self):
+        self._socket.close()
+
+    def write(self, data):
+        self._socket.send(data)
+
+    def readline(self):
+        recv = self._socket.recv
+        data = self._buf
+        while True:
+            i = 1 + data.find('\n')
+            if i:
+                self._buf = data[i:]
+                return data[:i]
+            d = recv(4096)
+            data += d
+            if not d:
+                self._buf = ''
+                return data
+
+    def flush(self):
+        pass
+
+    def closed(self):
+        self._socket.setblocking(0)
+        try:
+            self._socket.recv(0)
+            return True
+        except socket.error, (err, _):
+            if err != errno.EAGAIN:
+                raise
+            self._socket.setblocking(1)
+        return False
+
+
+class Console(object):
+
+    def __init__(self, path, pdb):
+        self.path = path
+        s = socket.socket(socket.AF_UNIX)
+        try:
+            self.close()
+        except OSError, e:
+            if e.errno != errno.ENOENT:
+                raise
+        s.bind(path)
+        s.listen(5)
+        def accept():
+            t = threading.Thread(target=pdb, args=(Socket(s.accept()[0]),))
+            t.daemon = True
+            t.start()
+        def select(r, w, t):
+            r[s] = accept
+        self.select = select
+
+    def close(self):
+        if stat.S_ISSOCK(os.lstat(self.path).st_mode):
+            os.remove(self.path)