first comit

venv/lib/python3.10/site-packages/jupyter_client/ssh/forward.py

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+"""Sample script showing how to do local port forwarding over paramiko.
+
+This script connects to the requested SSH server and sets up local port
+forwarding (the openssh -L option) from a local port through a tunneled
+connection to a destination reachable from the SSH server machine.
+"""
+#
+# This file is adapted from a paramiko demo, and thus licensed under LGPL 2.1.
+# Original Copyright (C) 2003-2007  Robey Pointer <robeypointer@gmail.com>
+# Edits Copyright (C) 2010 The IPython Team
+#
+# Paramiko is free software; you can redistribute it and/or modify it under the
+# terms of the GNU Lesser General Public License as published by the Free
+# Software Foundation; either version 2.1 of the License, or (at your option)
+# any later version.
+#
+# Paramiko is distributed in the hope that it will be useful, but WITHOUT ANY
+# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+# A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more
+# details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with Paramiko; if not, write to the Free Software Foundation, Inc.,
+# 51 Franklin Street, Fifth Floor, Boston, MA  02111-1301  USA.
+import logging
+import select
+import socketserver
+import typing as t
+
+logger = logging.getLogger("ssh")
+
+
+class ForwardServer(socketserver.ThreadingTCPServer):
+    """A server to use for ssh forwarding."""
+
+    daemon_threads = True
+    allow_reuse_address = True
+
+
+class Handler(socketserver.BaseRequestHandler):
+    """A handle for server requests."""
+
+    @t.no_type_check
+    def handle(self):
+        """Handle a request."""
+        try:
+            chan = self.ssh_transport.open_channel(
+                "direct-tcpip",
+                (self.chain_host, self.chain_port),
+                self.request.getpeername(),
+            )
+        except Exception as e:
+            logger.debug(
+                "Incoming request to %s:%d failed: %s" % (self.chain_host, self.chain_port, repr(e))
+            )
+            return
+        if chan is None:
+            logger.debug(
+                "Incoming request to %s:%d was rejected by the SSH server."
+                % (self.chain_host, self.chain_port)
+            )
+            return
+
+        logger.debug(
+            "Connected!  Tunnel open {!r} -> {!r} -> {!r}".format(
+                self.request.getpeername(),
+                chan.getpeername(),
+                (self.chain_host, self.chain_port),
+            )
+        )
+        while True:
+            r, w, x = select.select([self.request, chan], [], [])
+            if self.request in r:
+                data = self.request.recv(1024)
+                if len(data) == 0:
+                    break
+                chan.send(data)
+            if chan in r:
+                data = chan.recv(1024)
+                if len(data) == 0:
+                    break
+                self.request.send(data)
+        chan.close()
+        self.request.close()
+        logger.debug("Tunnel closed ")
+
+
+def forward_tunnel(local_port: int, remote_host: str, remote_port: int, transport: t.Any) -> None:
+    """Forward an ssh tunnel."""
+
+    # this is a little convoluted, but lets me configure things for the Handler
+    # object.  (SocketServer doesn't give Handlers any way to access the outer
+    # server normally.)
+    class SubHander(Handler):
+        chain_host = remote_host
+        chain_port = remote_port
+        ssh_transport = transport
+
+    ForwardServer(("127.0.0.1", local_port), SubHander).serve_forever()
+
+
+__all__ = ["forward_tunnel"]