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https://github.com/retspen/webvirtcloud
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1d2de7404b
ssh's error output went to a pipe that nobody read while the console ran: once it filled, ssh stopped and the console froze. It now goes to a temporary file, read when the tunnel closes. Closing waits five seconds for ssh to end and then kills it, instead of waiting for ever. The Tunnel holds the ssh process and its error file together.
59 lines
2.2 KiB
Python
59 lines
2.2 KiB
Python
"""The VNC console of an SSH compute, carried by the SSH connection: `ssh -W`
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forwards its standard input and output to the console's address or Unix
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socket on the compute, so the compute needs no nc and runs no shell."""
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import ipaddress
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import socket
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import subprocess
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import tempfile
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def tunnel_target(address, port, unix_socket):
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"""Where on the compute ssh forwards to: the Unix socket, or the address
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and port, a wildcard or missing address meaning the compute's loopback."""
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if unix_socket:
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return unix_socket
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address = {None: "127.0.0.1", "": "127.0.0.1", "0.0.0.0": "127.0.0.1", "::": "::1"}.get(address, address)
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try:
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if ipaddress.ip_address(address).version == 6:
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address = f"[{address}]"
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except ValueError: # a host name
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pass
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return f"{address}:{port}"
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class Tunnel:
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"""The ssh process that carries a console, and its error output, kept in
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a file: a pipe nobody reads while the console runs would stop ssh once
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it filled."""
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def __init__(self, argv, sock):
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self.errors = tempfile.TemporaryFile()
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self.process = subprocess.Popen(argv, stdin=sock, stdout=sock, stderr=self.errors)
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def close(self):
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"""End ssh, killed if it does not stop within 5 seconds; its error
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output if it failed, else ""."""
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if self.process.poll() is None:
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self.process.terminate()
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try:
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self.process.wait(5)
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except subprocess.TimeoutExpired:
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self.process.kill()
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self.process.wait()
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self.errors.seek(0)
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error = self.errors.read().decode(errors="replace").strip()
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self.errors.close()
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return error if self.process.returncode not in (0, -15) else ""
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def open_tunnel(host, user, target):
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"""A socket connected to target on host, and the Tunnel carrying it.
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ssh never asks for anything: a missing key or an unknown host key fails."""
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ours, theirs = socket.socketpair()
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argv = ["ssh", "-o", "BatchMode=yes", "-o", "ConnectTimeout=10", "-W", target]
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if user:
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argv += ["-l", user]
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tunnel = Tunnel(argv + ["--", host], theirs)
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theirs.close()
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return ours, tunnel
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