Issue with port forward when name contain quotes

[chemelli74]

I have a port forward rule named "Let's Encrypt". Unfortunately when you try to disable/enable it you get a bad parameters.

I suspect quoting is not handled correctly. Will try to investigate further, but before forgetting I though to log this issue.

Simone

[chemelli74]

This is the trace:

fritzconnection->call_action (log added by me):

2021-07-12 15:13:06 ERROR (SyncWorker_5) [fritzconnection] Simone: call service <WANPPPConnection1> with action <AddPortMapping>
and params <{'NewRemoteHost': '0.0.0.0', 'NewExternalPort': 80, 'NewProtocol': 'TCP', 'NewInternalPort': 80, 'NewInternalClient': '192.168.xxx.yyy', 'NewEnabled': '1', 'NewPortMappingDescription': "Let's Encrypt Renewal", 'NewLeaseDuration': 0}>

from HomeAssistant side:

2021-07-12 15:13:06 ERROR (SyncWorker_5) [homeassistant.components.fritz.switch] Connection Error: Please check the device is properly configured for remote login
Traceback (most recent call last):
  File "/usr/src/homeassistant/homeassistant/components/fritz/switch.py", line 72, in service_call_action
    return fritzbox_tools.connection.call_action(  # type: ignore[no-any-return]
  File "/usr/local/lib/python3.9/site-packages/fritzconnection/core/fritzconnection.py", line 229, in call_action
    return self.soaper.execute(service, action_name, arguments)
  File "/usr/local/lib/python3.9/site-packages/fritzconnection/core/soaper.py", line 238, in execute
    return handle_response(response)
  File "/usr/local/lib/python3.9/site-packages/fritzconnection/core/soaper.py", line 222, in handle_response
    raise_fritzconnection_error(response)
  File "/usr/local/lib/python3.9/site-packages/fritzconnection/core/soaper.py", line 147, in raise_fritzconnection_error
    raise exception(message)
fritzconnection.core.exceptions.FritzArgumentError: UPnPError:
errorCode: 402
errorDescription: Invalid Args

do you have an idea on how to escape the offending part ?

 'NewPortMappingDescription': "Let's Encrypt Renewal"

Simone

[chemelli74]

As a reminder, this is the part of the code to check better:

https://github.com/kbr/fritzconnection/blob/cadc128c47d82863cb77f82cddb29c0eb27fffba/fritzconnection/core/soaper.py#L228-L230

Simone

[kbr]

Why do you think this code is critical?

[chemelli74]

Why do you think this code is critical?

Not critical, but I think this is the part of the code responsible to create the arguments for the body of the requests. Thus the place to investigate more in depth how to correctly escape descriptions with quotes.

Simone

[kbr]

Everything is unicode. Until line 232 where the request gets converted to an utf-8 encoded byte-string. I suppose the PortMappingDescription has the same AllowedChars set like the ones for Password and Username where a single-quote is not included. That would explain the error description reported from the box.

[chemelli74]

PortMappingDescription allows the single quote at least in Fritzbox UI and I can easily get the status of that port via call_action as shown above. Only issue is with AddAction.

I cannot find a list of not allowed chars for descriptions: https://service.avm.de/help/en/FRITZ-Box-Fon-WLAN-7490/018/hilfe_zeichen_fuer_kennwoerter

Simone

[chemelli74]

I may have found something useful.

From https://avm.de/fileadmin/user_upload/Global/Service/Schnittstellen/x_appsetup.pdf:

[kbr]

Currently I have no idea why it doesn't work. Just keep in mind that FritzBox UI and TR064 are different interfaces. And regarding the link please fetch the document matching the used service. In your case this is https://avm.de/fileadmin/user_upload/Global/Service/Schnittstellen/wanpppconnSCPD.pdf.

If you can read the description string "Let's Encrypt" via TR064 but can't send it, you may try to find out, whether there is a special escaping in the received response (I doubt this) and try to use this for sending.

[chemelli74]

Debugged and found the value in the response.content:

<NewPortMappingDescription>Let&apos;s Encrypt Renewal</NewPortMappingDescription>

Simone

[chemelli74]

Found the list:

Simone

[chemelli74]

With the following code:

from xml.sax.saxutils import escape

test_string = "this is a list of strings: 1=&  2='  3=<  4=> 5=\""

# Only escapes &, <, and > by default
escaped = escape(test_string, entities={
        "'": "&apos;",
        "\"": "&quot;"
    })

print(escaped)

result is:

this is a list of strings: 1=& 2=' 3=< 4=> 5="

:-)

Simone

[kbr]

Ahhh, thanks – seems to be I was captured by the term escape characters, but it is about entity encodings. That's html basic stuff. No idea why I didn't get this right at the beginning. Will have a look at it :-)

[chemelli74]

Ahhh, thanks – seems to be I was captured by the term escape characters, but it is about entity encodings. That's html basic stuff. No idea why I didn't get this right at the beginning. Will have a look at it :-)

Please check https://github.com/kbr/fritzconnection/pull/115. Seems to work fine for all chars but the quote :-(

I added a log line for the body and it seems ok:

2021-07-17 15:29:12 DEBUG (SyncWorker_8) [test-simone] body=b'<?xml version="1.0" encoding="utf-8"?><s:Envelope s:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/" xmlns:s="http://schemas.xmlsoap.org/soap/envelope/"><s:Body><u:AddPortMapping xmlns:u="urn:dslforum-org:service:WANPPPConnection:1"><NewRemoteHost>0.0.0.0</NewRemoteHost><NewExternalPort>80</NewExternalPort><NewProtocol>TCP</NewProtocol><NewInternalPort>80</NewInternalPort><NewInternalClient>192.168.188.42</NewInternalClient><NewEnabled>1</NewEnabled><NewPortMappingDescription>Let&apos;s Encrypt Renewal</NewPortMappingDescription><NewLeaseDuration>0</NewLeaseDuration></u:AddPortMapping></s:Body></s:Envelope>'

Simone

[chemelli74]

Comparing XML response "GetGenericPortMappingEntryResponse" and XML sent for "AddPortMapping" the only difference is:

encoding="utf-8"

Simone

[kbr]

Please see my comment on #115

[chemelli74]

Logged a ticket with AVM. Reference: Ticket-ID 4421905

Simone

[chemelli74]

Logged a ticket with AVM. Reference: Ticket-ID 4421905

Simone

Official reply:

As of today the supported characters for PortMappingDescription via TR-064 are:

- a-Z  
- 0-9 
- white space 
- hyphen 
- underline 

Unfortunately the documentation does not mention this in detail.
We apologize for related inconveniences and try to improve. 

Simone