(untested) slave shall now ask for the server secret key for symmetric communications

source/behaviors/events/DiscoveryEvent.py

@@ -1,6 +1,6 @@
 from . import base
 from source import packets
-from ...packets import PeerPacket
+from .. import roles
 from ...utils.crypto.type import CipherType
 
 
@@ -11,6 +11,9 @@ class DiscoveryEvent(base.BaseEvent):
 
     def handle(self, packet: packets.DiscoveryPacket, address: tuple):
         # create a peer packet containing our important information
-        peerPacket = PeerPacket(self.manager.communication.public_key)
+        peerPacket = packets.PeerPacket(
+            self.manager.communication.public_key,
+            isinstance(self.manager.role, roles.MasterRole)
+        )
         # send our information back
         self.manager.communication.send(peerPacket, CipherType.PLAIN, address)

source/behaviors/events/KeyEvent.py

@@ -0,0 +1,20 @@
+from source import packets
+from source.behaviors import roles
+from source.behaviors.events import base
+
+
+class KeyEvent(base.BaseEvent):
+    """
+    Event reacting to a machine sending us their secret key
+    """
+
+    def handle(self, packet: packets.KeyPacket, address: tuple):
+        # check if we are a slave
+        if not isinstance(self.manager.role, roles.SlaveRole):
+            return
+
+        # TODO(Faraphel): check if this come from our server ?
+
+        # use the secret key for further symmetric communication
+        # TODO(Faraphel): should not be an attribute of the manager communication system, create a dictionary with the secret key of the servers ?
+        self.manager.communication.secret_key = packet.secret_key

source/behaviors/events/RequestKeyEvent.py

@@ -0,0 +1,22 @@
+from source import packets
+from source.behaviors import roles
+from source.behaviors.events import base
+from source.utils.crypto.type import CipherType
+
+
+class RequestKeyEvent(base.BaseEvent):
+    """
+    Event reacting to a machine trying to get our secret symmetric key for secure communication
+    """
+
+    def handle(self, packet: packets.RequestKeyPacket, address: tuple):
+        # check if we are a master
+        if not isinstance(self.manager.role, roles.MasterRole):
+            return
+
+        # create a packet containing our secret key
+        packet = packets.KeyPacket(self.manager.communication.secret_key)
+        # send it back to the slave
+        self.manager.communication.send(packet, CipherType.RSA, address)
+
+        # TODO(Faraphel): check if we trust the slave ?

source/behaviors/events/__init__.py

@@ -2,4 +2,6 @@ from . import base
 
 from .DiscoveryEvent import DiscoveryEvent
 from .PeerEvent import PeerEvent
-from .AudioEvent import AudioEvent
+from .AudioEvent import AudioEvent
+from .RequestKeyEvent import RequestKeyEvent
+from .KeyEvent import KeyEvent

source/behaviors/roles/MasterRole.py

@@ -27,7 +27,7 @@ class MasterRole(base.BaseRole):
 
         # prepare the audio file that will be streamed
         # TODO(Faraphel): use another audio source
-        self.audio = pydub.AudioSegment.from_file("../assets/Caravan Palace - Wonderland.mp3")
+        self.audio = pydub.AudioSegment.from_file("../assets/Queen - Another One Bites the Dust.mp3")
         self.play_time = datetime.now()
 
         # calculate the number of bytes per milliseconds in the audio
@@ -36,6 +36,7 @@ class MasterRole(base.BaseRole):
         self.chunk_duration = timedelta(milliseconds=self.TARGET_SIZE / bytes_per_ms)
 
         # split the audio into chunks
+        self.chunk_count = 0
         self.chunks = make_chunks(self.audio, self.chunk_duration.total_seconds() * 1000)
 
 
@@ -44,8 +45,8 @@ class MasterRole(base.BaseRole):
         # TODO(Faraphel): share the secret key generated with the other *allowed* peers ! How to select them ? A file ?
         # TODO(Faraphel): check if another server is emitting sound in the network. Return to undefined if yes
 
-        # get the next chunk
-        chunk = self.chunks.pop(0)
+        # get the current chunk
+        chunk = self.chunks[self.chunk_count]
 
         # broadcast it in the network
         audio_packet = AudioPacket(
@@ -58,6 +59,8 @@ class MasterRole(base.BaseRole):
         )
         self.manager.communication.broadcast(audio_packet, CipherType.AES_CBC)
 
-        # wait for the audio to play
-        # TODO(Faraphel): should adapt to the compute time above
-        pause.until(datetime.now() + self.chunk_duration)
+        # increment the chunk count
+        self.chunk_count += 1
+
+        # wait for the next chunk time
+        pause.until(self.play_time + (self.chunk_duration * self.chunk_count))

source/behaviors/roles/SlaveRole.py

@@ -1,4 +1,7 @@
+from source import managers, packets
 from source.behaviors.roles import base
+from source.utils.crypto.type import CipherType
+
 
 class SlaveRole(base.BaseRole):
     """
@@ -6,6 +9,16 @@ class SlaveRole(base.BaseRole):
     It shall listen for a master and check if everything is working properly
     """
 
+    def __init__(self, manager: "managers.Manager", master_address: tuple):
+        super().__init__(manager)
+
+        # the address of the server
+        self.master_address = master_address
+
     def handle(self):
-        # TODO(Faraphel): ping the server and check if it is working properly. Return to undefined if no.
-        pass
+        # TODO(Faraphel): ping the master and check if it is working properly. Return to undefined if no.
+
+        # NOTE(Faraphel): the secret key might be stored somewhere else than here, or need to be reset
+        if self.manager.communication.secret_key is None:
+            packet = packets.RequestKeyPacket()
+            self.manager.communication.send(packet, CipherType.AES_CBC, self.master_address)

source/behaviors/roles/UndefinedRole.py

@@ -4,6 +4,7 @@ from datetime import datetime, timedelta
 from . import base, MasterRole
 
 from source import packets
+from .SlaveRole import SlaveRole
 from ...managers import Manager
 from ...utils.crypto.type import CipherType
 
@@ -35,8 +36,38 @@ class UndefinedRole(base.BaseRole):
 
         # check if no more peers have been found in the previous seconds
         if datetime.now() - self.previous_discovery >= timedelta(seconds=5):
-            # check if no peer have been found except ourselves.
-            # TODO(Faraphel): need a better check than just that
-            if len(self.manager.peers) == 1:
-                # if we are the only machine, become a master
+            # SCENARIO 1 - empty network
+
+            # filter ourselves out of the remote peers
+            remote_peers = {
+                address: peer
+                for (address, peer) in self.manager.peers.items()
+                if not self.manager.communication.is_address_local(address)
+            }
+
+            # if no other peers have been found
+            if len(remote_peers) == 0:
+                # declare ourselves as the master of the network
                 self.manager.role.current = MasterRole(self.manager)
+                return
+
+            # SCENARIO 2 - network with a master
+
+            # list all the peers considered as masters
+            master_peers = {
+                address: peer
+                for (address, peer) in remote_peers.items()
+                if peer.master
+            }
+
+            # if there is a master, become a slave
+            if len(master_peers) >= 1:
+                master_address, master_peer = master_peers[0]
+
+                # declare ourselves as a slave of the network
+                self.manager.role.current = SlaveRole(self.manager, master_address)
+
+            # SCENARIO 3 - network with no master
+
+            # TODO(Faraphel): elect the machine with the lowest ping in the network
+            raise NotImplementedError("Not implemented: elect the machine with the lowest ping as a master.")

source/behaviors/roles/__init__.py

@@ -1,4 +1,5 @@
 from . import base
 
 from .MasterRole import MasterRole
-from .UndefinedRole import UndefinedRole
+from .SlaveRole import SlaveRole
+from .UndefinedRole import UndefinedRole

source/managers/CommunicationManager.py

@@ -171,3 +171,33 @@ class CommunicationManager:
         payload, address = self.socket.recvfrom(65536)
         # decode the payload
         return self.packet_decode(payload), address
+
+    @staticmethod
+    def get_local_addresses() -> list[tuple]:
+        """
+        Get the local addresses of the machine
+        :return: the local addresses of the machine
+        """
+
+        return socket.getaddrinfo(socket.gethostname(), None)
+
+    def is_address_local(self, address: tuple) -> bool:
+        """
+        Is the given address local
+        :return: true if the address is local, false otherwise
+        """
+
+        host, _, _, scope = address
+
+        # check for all the interfaces of our machine
+        for interface in self.get_local_addresses():
+            # unpack the interface information
+            interface_family, _, _, _, interface_address = interface
+            interface_host, _, _, interface_scope = interface_address
+
+            # check if it matches the address interface
+            if host == interface_host and scope == interface_scope:
+                return True
+
+        # no matching interfaces have been found
+        return False

source/managers/Manager.py

@@ -17,12 +17,16 @@ class Manager:
         self.communication.register_packet_type(b"DISC", packets.DiscoveryPacket)
         self.communication.register_packet_type(b"PEER", packets.PeerPacket)
         self.communication.register_packet_type(b"AUDI", packets.AudioPacket)
+        self.communication.register_packet_type(b"RQSK", packets.RequestKeyPacket)
+        self.communication.register_packet_type(b"GTSK", packets.KeyPacket)
 
         # event manager
         self.event = EventManager(self)
         self.event.register_event_handler(packets.DiscoveryPacket, events.DiscoveryEvent(self))
         self.event.register_event_handler(packets.PeerPacket, events.PeerEvent(self))
         self.event.register_event_handler(packets.AudioPacket, events.AudioEvent(self))
+        self.event.register_event_handler(packets.RequestKeyPacket, events.RequestKeyEvent(self))
+        self.event.register_event_handler(packets.KeyPacket, events.KeyEvent(self))
 
         # role manager
         self.role = RoleManager(self)

source/packets/KeyPacket.py

@@ -0,0 +1,23 @@
+import dataclasses
+
+import msgpack
+
+from source.packets import base
+
+
+@dataclasses.dataclass
+class KeyPacket(base.BasePacket):
+    """
+    Represent a packet containing a secret symmetric key
+    """
+
+    secret_key: bytes = dataclasses.field(repr=False)
+
+    def pack(self) -> bytes:
+        return msgpack.packb((
+            self.secret_key
+        ))
+
+    @classmethod
+    def unpack(cls, data: bytes):
+        return cls(*msgpack.unpackb(data))

source/packets/PeerPacket.py

@@ -14,9 +14,13 @@ class PeerPacket(base.BasePacket):
     # public RSA key of the machine
     public_key: bytes = dataclasses.field(repr=False)
 
+    # is the machine a master
+    master: bool = dataclasses.field()
+
     def pack(self) -> bytes:
         return msgpack.packb((
             self.public_key,
+            self.master
         ))
 
     @classmethod

source/packets/RequestKeyPacket.py

@@ -0,0 +1,19 @@
+import dataclasses
+
+import msgpack
+
+from source.packets import base
+
+
+@dataclasses.dataclass
+class RequestKeyPacket(base.BasePacket):
+    """
+    Represent a packet used to request a secret symmetric key
+    """
+
+    def pack(self) -> bytes:
+        return msgpack.packb(())
+
+    @classmethod
+    def unpack(cls, data: bytes):
+        return cls()

source/packets/__init__.py

@@ -3,3 +3,5 @@ from . import base
 from .AudioPacket import AudioPacket
 from .DiscoveryPacket import DiscoveryPacket
 from .PeerPacket import PeerPacket
+from .RequestKeyPacket import RequestKeyPacket
+from .KeyPacket import KeyPacket