btdht.krcp module¶

class btdht.krcp.BError¶

Bases: exceptions.Exception

A base class exception for all bittorrent DHT protocol error exceptions

Parameters:	t (bytes) – The value of the key t of the query for with the error is returned e (list) – A couple [error code, error message]

e = None¶: A list. The first element is an int representing the error code. The second element is a string containing the error message

t = None¶: string value representing a transaction ID, must be set to the query transaction ID for which an error is raises.

y = 'e'¶: The y key of the error message. For an error message, it is always b"e"

encode()¶

Bencode the error message

Returns:	The bencoded error message ready to be send
Return type:	bytes

class btdht.krcp.GenericError¶

Bases: btdht.krcp.BError

A Generic Error, error code 201

Parameters:	t (bytes) – The value of the key t of the query for with the error is returned msg (bytes) – An optionnal error message

class btdht.krcp.MethodUnknownError¶

Bases: btdht.krcp.BError

Method Unknown, error code 204

Parameters:	t (bytes) – The value of the key t of the query for with the error is returned msg (bytes) – An optionnal error message

class btdht.krcp.ProtocolError¶

Bases: btdht.krcp.BError

A Protocol Error, such as a malformed packet, invalid arguments, or bad token, error code 203

Parameters:	t (bytes) – The value of the key t of the query for with the error is returned msg (bytes) – An optionnal error message

class btdht.krcp.ServerError¶

Bases: btdht.krcp.BError

A Server Error, error code 202

Parameters:	t (bytes) – The value of the key t of the query for with the error is returned msg (bytes) – An optionnal error message

class btdht.krcp.BMessage¶

Bases: object

A bittorrent DHT message. This class is able to bdecode a bittorrent DHT message. It expose then the messages keys t, y, q, errno, errmsg and v as attributes, and behave itself as a dictionnary for the a or r keys that contains a secondary dictionnary (see Notes).

Parameters:	addr (tuple) – An optionnal coupe (ip, port) of the sender of the message debug (bool) – `True` for enabling debug message. The default is `False`

Notes:

A query message is always of the following form with y == b'q':

{
    "t": t,
    "y": y,
    "q": q, 
    "a": {...}
}

A response message is always of the following form with y == b'r':

{
    "t": t,
    "y": y,
    "r": {...}
}

An error message is always in response of a query message and of the following form with y == b'e':

{
    "t": t,
    "y": y,
    "e":[errno, errmsg]
}

The t key is a random string generated with every query. It is used to match a response to a particular query.

The y key is used to differenciate the type of the message. Its value is b'q' for a query, b'r' for a response, and b'e' for and error message.

The q is only present on query message and contain the name of the query (ping, get_peers, announce_peer, find_node)

errno and errmsg are only defined if the message is an error message. They are respectively the error number (int) and the error describing message of the error.

The v key is set by some DHT clients to the name and version of the client and is totally optionnal in the protocol.

addr¶: The couple (ip, port) source of the message

errmsg¶: The error message of the message if the message is and erro message

errno¶: The error number of the message if the message is and erro message

q¶: The q key of the message, should only be define if the message is a query (y is "q"). It countains the name of the RPC method the query is asking for. Can be b’ping’`, b'find_node', b'get_peers', b'announce_peer', …

t¶: The t key, a random string, transaction id used to match queries and responses together.

v¶: The v key of the message. This attribute is not describe in the BEP5 that describe the bittorent DHT protocol. It it use as a version flag. Many bittorent client set it to the name and version of the client.

y¶: The y` key of the message. Possible value are ``"q" for a query, “r” for a response and "e" for an error.

__getitem__(key)¶

Allow to fetch infos from the secondary dictionnary:

self[b"id"] -> b"..."

Parameters:	key (bytes) – The name of an attribute of the secondary dictionnary to retreive.
Returns:	The value store for `key` if found
Raises:	KeyError – if `key` is not found

Notes:

Possible keys are:

id
target
info_hash
token
nodes
implied_port
port
values

__delitem__(key)¶

Allow to unset attributes from the secondary dictionnary:

del self[b'id']

Parameters:	bytes key (:param) – The name of an attribute of the secondary dictionnary to unset
Returns:	`True` if `key` is found and successfully unset
Raises:	KeyError – if `key` is not found

__setitem__(key, value)¶

Allow to set attributes from the secondary dictionnary:

self[b'id'] = b"..."

Parameters:	key (bytes) – The name of an attribute of the secondary dictionnary to set value – The value to set
Raises:	KeyError – if `key` is not one of id, target, info_hash, token, nodes, implied_port, port, values. ValueError – if `value` is not well formated (length, type, …)

decode(data, datalen)¶

Bdecode a bencoded message and set the current BMessage attributes accordingly

Parameters:	data (bytes) – The bencoded message datalen (int) – The length of `data`
Returns:	The remaining of `data` after the first bencoded message of `data` has been bdecoded (it may be the empty string if `data` contains exactly one bencoded message with no garbade at the end).
Raises:	DecodeError – If we fail to decode the message ProtocolError – If the message is decoded but some attributes are missing of badly formated (length, type, …). MissingT – If the message do not have a `b"t"` key. Indeed, accordingly to the BEP5, every message (queries, responses, errors) should have a `b"t"` key.

encode()¶

Bencoded the current message if necessary

Returns:	The bencoded message
Return type:	bytes

get(key, default=None)¶

Parameters:	key (bytes) – The name of an attribute of the secondary dictionnary to retreive. default – Value to return in case `key` is not found. The default is `None`
Returns:	The value of `key` if found, else the value of `default`.

response(dht)¶

If the message is a query, return the response message to send

Parameters:	dht (dht.DHT_BASE) – The dht instance from which the message is originated
Returns:	A `BMessage` to send as response to the query
Raises:	ProtocolError – if the query is malformated. To send as response to the querier MethodUnknownError – If the RPC DHT method asked in the query is unknown. To send as response to the querier