[CRIU] [PATCH 2/2] p.haul: use ssh tunneling and controll it with ssh* cmdline opts

[Pavel Emelyanov]

On 10/27/2014 11:53 PM, Ruslan Kuprieiev wrote:
> On 27.10.2014 20:39, Pavel Emelyanov wrote:
>> 		_rpc_proxy_caller(self._rpc_sk, RPC_CMD, "init_rpc")(args)
>>>>> @@ -51,7 +57,17 @@ class rpc_proxy:
>>>>>    
>>>>>    	def _make_sk(self):
>>>>>    		sk = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
>>>>> -		sk.connect((self._srv, rpc_port))
>>>>> +		# ssh tunnel needs some time to start working, so lets
>>>>> +		# make CONNECT_ATTEMPTS attempts to connect.
>>>> I don't like it. Can you shed more light on what's going on here?
>>> We have no way to check if ssh tunnel is created other than try to connect.
>> Yes, and AFAIU when you connect to local ssh, it "blocks" the
>> connection and goes to connect remotely. I don't see the need
>> in retries.
> 
> There is a race condition happening, ssh can't bind to local port so fast.

Ah, I see. Anyway strange. There should be a race-free way of
asking ssh to report back smth when the socket is created and
ready to serve.

> So we need to try to connect a bunch of times(not using connection timeout)
> and only then fail.
> 
>>> But I should have used connection timeout here =). Will fix.
>>>
>>>>> +		for n in xrange(CONNECT_ATTEMPTS):
>>>>> +			try:
>>>>> +				sk.connect(self._srv)
>>>>> +			except socket.error as e:
>>>>> +				if e.errno != errno.ECONNREFUSED or n == CONNECT_ATTEMPTS - 1:
>>>>> +					raise e
>>>>> +				else:
>>>>> +					continue
>>>>> +			break
>>>>>    		host = _rpc_proxy_caller(sk, RPC_CMD, "get_name")()
>>>>>    		return (sk, host)
>>>>>    
> 
> .
>