106 lines
4.5 KiB
Python
106 lines
4.5 KiB
Python
from abc import ABC
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from collections import OrderedDict
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from typing import Mapping
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from libp2p.network.connection.raw_connection_interface import IRawConnection
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from libp2p.peer.id import ID
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from libp2p.protocol_muxer.multiselect import Multiselect
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from libp2p.protocol_muxer.multiselect_client import MultiselectClient
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from libp2p.protocol_muxer.multiselect_communicator import RawConnectionCommunicator
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from libp2p.security.secure_conn_interface import ISecureConn
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from libp2p.security.secure_transport_interface import ISecureTransport
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from libp2p.typing import TProtocol
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"""
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Represents a secured connection object, which includes a connection and details about the security
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involved in the secured connection
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Relevant go repo: https://github.com/libp2p/go-conn-security/blob/master/interface.go
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"""
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class SecurityMultistream(ABC):
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"""
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SSMuxer is a multistream stream security transport multiplexer.
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Go implementation: github.com/libp2p/go-conn-security-multistream/ssms.go
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"""
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# NOTE: Can be changed to `typing.OrderedDict` since Python 3.7.2.
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transports: "OrderedDict[TProtocol, ISecureTransport]"
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multiselect: Multiselect
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multiselect_client: MultiselectClient
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def __init__(
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self, secure_transports_by_protocol: Mapping[TProtocol, ISecureTransport]
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) -> None:
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self.transports = OrderedDict()
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self.multiselect = Multiselect()
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self.multiselect_client = MultiselectClient()
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for protocol, transport in secure_transports_by_protocol.items():
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self.add_transport(protocol, transport)
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def add_transport(self, protocol: TProtocol, transport: ISecureTransport) -> None:
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"""
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Add a protocol and its corresponding transport to multistream-select(multiselect).
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The order that a protocol is added is exactly the precedence it is negotiated in
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multiselect.
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:param protocol: the protocol name, which is negotiated in multiselect.
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:param transport: the corresponding transportation to the ``protocol``.
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"""
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# If protocol is already added before, remove it and add it again.
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if protocol in self.transports:
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del self.transports[protocol]
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self.transports[protocol] = transport
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# Note: None is added as the handler for the given protocol since
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# we only care about selecting the protocol, not any handler function
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self.multiselect.add_handler(protocol, None)
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async def secure_inbound(self, conn: IRawConnection) -> ISecureConn:
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"""
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Secure the connection, either locally or by communicating with opposing node via conn,
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for an inbound connection (i.e. we are not the initiator)
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:return: secure connection object (that implements secure_conn_interface)
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"""
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transport = await self.select_transport(conn, False)
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secure_conn = await transport.secure_inbound(conn)
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return secure_conn
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async def secure_outbound(self, conn: IRawConnection, peer_id: ID) -> ISecureConn:
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"""
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Secure the connection, either locally or by communicating with opposing node via conn,
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for an inbound connection (i.e. we are the initiator)
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:return: secure connection object (that implements secure_conn_interface)
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"""
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transport = await self.select_transport(conn, True)
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secure_conn = await transport.secure_outbound(conn, peer_id)
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return secure_conn
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async def select_transport(
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self, conn: IRawConnection, initiator: bool
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) -> ISecureTransport:
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"""
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Select a transport that both us and the node on the
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other end of conn support and agree on
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:param conn: conn to choose a transport over
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:param initiator: true if we are the initiator, false otherwise
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:return: selected secure transport
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"""
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# TODO: Is conn acceptable to multiselect/multiselect_client
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# instead of stream? In go repo, they pass in a raw conn
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# (https://raw.githubusercontent.com/libp2p/go-conn-security-multistream/master/ssms.go)
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protocol: TProtocol
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communicator = RawConnectionCommunicator(conn)
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if initiator:
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# Select protocol if initiator
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protocol = await self.multiselect_client.select_one_of(
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list(self.transports.keys()), communicator
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)
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else:
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# Select protocol if non-initiator
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protocol, _ = await self.multiselect.negotiate(communicator)
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# Return transport from protocol
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return self.transports[protocol]
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