Telegram.org API: calling method invokeWithLayer in Python

Question

In reference to How to implement authorization using a Telegram API? This is the best telegram documentation I have yet to find! Thanks for that.

I am attempting to create a Python library to make calls to telegram.org. I can authenticate as described in the above link but ran into issues with method responses returning in a format found only in a previous layer. In other words, my client is calling a method from one layer of the api but the server is responding with a data format from an older api layer. I confirmed this by searching an older api layer file for the return id.

{
    "id": "571849917",
    "params": [
        {
            "name": "phone_registered",
            "type": "Bool"
        },
        {
            "name": "phone_code_hash",
            "type": "string"
        }
    ],
    "predicate": "auth.sentCode",
    "type": "auth.SentCode"
},

The format my client is expecting is this:

{
    "id": "-269659687",
    "params": [
        {
            "name": "phone_registered",
            "type": "Bool"
        },
        {
            "name": "phone_code_hash",
            "type": "string"
        },
        {
            "name": "send_call_timeout",
            "type": "int"
        },
        {
            "name": "is_password",
            "type": "Bool"
        }
    ],
    "predicate": "auth.sentCode",
    "type": "auth.SentCode"
},

So, I read in the telegram docs I need to call invokeWithLayer to make sure the client and server have their api layers in synch.

Several questions:

1. Given a telegram api schema file, is there a way to determine from the schema which layer it is? Or do you just "simply have to know"?
2. When calling invokeWithLayer how do you format the 'query' parameter? Do you have to serialize the query first?

Here is my initConnection code where I serialize each method before using it as a parameter. Unfortunately, the response is not favorable. The first response is:

('initConnection - msg: ', {u'messages': [{u'body': {u'first_msg_id': 6312441942040617984L, u'unique_id': 986871592203578887L, u'server_salt': 7658270006181864880L}, u'seqno': 1, u'msg_id': 6312441944354392065L, u'bytes': 28}, {u'body': {u'msg_ids': [6312441942040617984L]}, u'seqno': 2, u'msg_id': 6312441944354450433L, u'bytes': 20}]})

The second response is:

{u'req_msg_id': 6312441942040617984L, u'result': {u'error_message': 'INPUT_METHOD_INVALID', u'error_code': 400}})

...and the code:

 def initConnection(self, config):
    '''Set the API layer and initialize the connection'''

    # get the required config data
    api_layer = config.getint('App data', 'api_layer')
    api_id = config.getint('App data', 'api_id')
    version = config.get('App data', 'version')
    print
    print('----------------------------------------------')
    print('initConnection - api_layer: ', api_layer)
    print('initConnection - api_id:    ', api_id)
    print('initConnection - version:   ', version)

    # serialize a candidate method as a parameter. It doesn't
    # matter what it is so we will use something simple like get_future_salts.
    simpleQuery=TL.tl_serialize_method('get_future_salts', num=3)

    # serialize the initConnection method
    initConnectionQuery = TL.api_serialize_method('initConnection', api_id=api_id,
                                                 device_model='Unknown UserAgent',
                                                 system_version='Unknown Platform',
                                                 app_version=version,
                                                 lang_code='en-US',
                                                 query=simpleQuery)

    # perform the initialization
    msg = self.method_call('invokeWithLayer', layer=api_layer, query=initConnectionQuery)
    print('initConnection - msg: ', msg)

Thanks!

Answer 1

1) I get the latest telegram schema from here: https://github.com/telegramdesktop/tdesktop/blob/master/Telegram/Resources/scheme.tl

You can build your own TL parser library that works the way you want it too, and easily update it to the latest as the versions change.

2) To send the X query param you simply serialize and append to the end of your invoke with layer query.

Example: (from my Telegram Elixir Library)

 msg = TL.invokewithlayer(layer, TL.initconnection(app_id, device_model, system_version, app_version, lang_code, TL.help_getconfig))

You can see the definition of relevant Telegram schema:

initConnection#69796de9 {X:Type} api_id:int device_model:string system_version:string app_version:string lang_code:string query:!X = X;
invokeWithLayer#da9b0d0d {X:Type} layer:int query:!X = X;