start implementing group chat server with membership management

database.py

@@ -123,3 +123,38 @@ class LxmfConversationReadState(BaseModel):
     # define table name
     class Meta:
         table_name = "lxmf_conversation_read_state"
+
+
+class Group(BaseModel):
+
+    id = BigAutoField()
+    destination_hash = CharField(unique=True)  # unique destination hash
+    identity_private_key = TextField(null=True)  # identity private key if we created and control this group
+    type = CharField()
+    public_display_name = CharField()
+
+    created_at = DateTimeField(default=lambda: datetime.now(timezone.utc))
+    updated_at = DateTimeField(default=lambda: datetime.now(timezone.utc))
+
+    # define table name
+    class Meta:
+        table_name = "groups"
+
+
+class GroupMember(BaseModel):
+
+    id = BigAutoField()
+    group_destination_hash = CharField()
+    member_identity_hash = CharField()
+    member_display_name = CharField()
+
+    created_at = DateTimeField(default=lambda: datetime.now(timezone.utc))
+    updated_at = DateTimeField(default=lambda: datetime.now(timezone.utc))
+
+    # define table name
+    class Meta:
+        table_name = "group_members"
+        constraints = [
+            # only allow a single row per group_destination_hash/member_identity_hash pair
+            SQL('UNIQUE (group_destination_hash, member_identity_hash)'),
+        ]

meshchat.py

@@ -23,6 +23,7 @@ from serial.tools import list_ports
 
 import database
 from src.backend.announce_handler import AnnounceHandler
+from src.backend.group_chat.group_chat_server import GroupChatServer, GroupDataProviderInterface
 from src.backend.lxmf_message_fields import LxmfImageField, LxmfFileAttachmentsField, LxmfFileAttachment, LxmfAudioField
 from src.backend.audio_call_manager import AudioCall, AudioCallManager
 
@@ -38,6 +39,79 @@ def get_file_path(filename):
     return os.path.join(datadir, filename)
 
 
+class GroupChatDataProvider(GroupDataProviderInterface):
+
+    def __init__(self):
+        pass
+
+    # finds a group in the database for the provided destination hash
+    def find_group(self, group_destination_hash: bytes):
+        return database.Group.get_or_none(database.Group.destination_hash == group_destination_hash.hex())
+
+    # gets member count of a group
+    def get_member_count(self, group_destination_hash: bytes) -> int:
+
+        # find group
+        group = self.find_group(group_destination_hash)
+        if group is None:
+            raise Exception("Group not found")
+
+        # get group members count
+        group_members_count = database.GroupMember.select().where(database.GroupMember.group_destination_hash == group.destination_hash).count()
+        return group_members_count
+
+    # check if a user is a member of a group
+    def is_member(self, group_destination_hash: bytes, identity_hash: bytes) -> bool:
+
+        # find group
+        group = self.find_group(group_destination_hash)
+        if group is None:
+            raise Exception("Group not found")
+
+        # find group member
+        group_member = database.GroupMember.get_or_none(
+            (database.GroupMember.group_destination_hash == group.destination_hash)
+            & (database.GroupMember.member_identity_hash == identity_hash.hex()))
+
+        return group_member is not None
+
+    # adds a member to a group
+    def add_member(self, group_destination_hash: bytes, identity_hash: bytes, display_name: str):
+
+        # find group
+        group = self.find_group(group_destination_hash)
+        if group is None:
+            raise Exception("Group not found")
+
+        # prepare data to insert or update
+        data = {
+            "group_destination_hash": group.destination_hash,
+            "member_identity_hash": identity_hash.hex(),
+            "member_display_name": display_name,
+            "updated_at": datetime.now(timezone.utc),
+        }
+
+        # upsert group member to database
+        database.GroupMember.insert(data).on_conflict(conflict_target=[
+            # one unique row per group_destination_hash/member_identity_hash pair
+            database.GroupMember.group_destination_hash,
+            database.GroupMember.member_identity_hash,
+        ], update=data).execute()
+
+    # removes a member from a group
+    def remove_member(self, group_destination_hash: bytes, identity_hash: bytes):
+
+        # find group
+        group = self.find_group(group_destination_hash)
+        if group is None:
+            raise Exception("Group not found")
+
+        # remove group member from database
+        database.GroupMember.delete().where(
+            (database.GroupMember.group_destination_hash == group.destination_hash)
+            & (database.GroupMember.member_identity_hash == identity_hash.hex())).execute()
+
+
 class ReticulumMeshChat:
 
     def __init__(self, identity: RNS.Identity, storage_dir, reticulum_config_dir):
@@ -72,6 +146,8 @@ class ReticulumMeshChat:
             database.Config,
             database.Announce,
             database.CustomDestinationDisplayName,
+            database.Group,
+            database.GroupMember,
             database.LxmfMessage,
             database.LxmfConversationReadState,
         ])
@@ -142,6 +218,22 @@ class ReticulumMeshChat:
         self.audio_call_manager = AudioCallManager(identity=self.identity)
         self.audio_call_manager.register_incoming_call_callback(self.on_incoming_audio_call)
 
+        # start group servers we control
+        self.group_chat_servers = []
+        for group in database.Group.get(database.Group.identity_private_key.is_null(False)).select():
+
+            # load group identity private key from database
+            group_identity = RNS.Identity(create_keys=False)
+            group_identity.load_private_key(base64.b64decode(group.identity_private_key))
+
+            # init group chat server
+            self.group_chat_servers.append(GroupChatServer(
+                identity=group_identity,
+                data_provider=GroupChatDataProvider(),
+                group_type=group.type,
+                public_display_name=group.public_display_name,
+            ))
+
         # start background thread for auto announce loop
         thread = threading.Thread(target=asyncio.run, args=(self.announce_loop(),))
         thread.daemon = True
@@ -892,6 +984,95 @@ class ReticulumMeshChat:
                 "announces": announces,
             })
 
+        # serve groups
+        @routes.get("/api/v1/groups")
+        async def index(request):
+
+            # build groups database query
+            query = database.Group.select()
+
+            # order groups by name asc
+            query_results = query.order_by(database.Group.public_display_name.asc())
+
+            # process groups
+            groups = []
+            for group in query_results:
+                groups.append(self.convert_db_group_to_dict(group))
+
+            return web.json_response({
+                "groups": groups,
+            })
+
+        # create group
+        @routes.post("/api/v1/groups/create")
+        async def index(request):
+
+            # get request data
+            data = await request.json()
+            group_type = data.get('group_type')
+            public_display_name = data.get('public_display_name')
+
+            # group type is required
+            # todo check group type is allowed
+            if group_type is None:
+                return web.json_response({
+                    "message": "group type is required",
+                }, status=422)
+
+            # public display name is required
+            if public_display_name is None or public_display_name == "":
+                return web.json_response({
+                    "message": "public display name is required",
+                }, status=422)
+
+            # create a new rns identity to manage this group
+            group_identity = RNS.Identity()
+
+            # determine the destination hash for this new group
+            destination_hash = RNS.Destination.hash(group_identity, "meshchat", "group").hex()
+
+            # create group in database
+            database.Group.insert({
+                "destination_hash": destination_hash,
+                "identity_private_key": base64.b64encode(group_identity.get_private_key()).decode("utf-8"),
+                "type": group_type,
+                "public_display_name": public_display_name,
+                "created_at": datetime.now(timezone.utc),
+                "updated_at": datetime.now(timezone.utc),
+            }).execute()
+
+            # find new group in database
+            database_group = database.Group.get_or_none(database.Group.destination_hash == destination_hash)
+            if database_group is None:
+                return web.json_response({
+                    "message": "failed to find group after creating it",
+                }, status=500)
+
+            return web.json_response({
+                "group": self.convert_db_group_to_dict(database_group),
+            })
+
+        # delete group
+        @routes.delete("/api/v1/groups/{destination_hash}")
+        async def index(request):
+
+            # get path params
+            destination_hash = request.match_info.get("destination_hash", None)
+
+            # destination hash is required
+            if destination_hash is None:
+                return web.json_response({
+                    "message": "destination hash is required",
+                }, status=422)
+
+            # delete all database records for the group
+            database.Group.delete().where((database.Group.destination_hash == destination_hash)).execute()
+            database.GroupMember.delete().where((database.GroupMember.group_destination_hash == destination_hash)).execute()
+
+            return web.json_response({
+                "message": "Group has been deleted",
+            })
+
         # propagation node status
         @routes.get("/api/v1/lxmf/propagation-node/status")
         async def index(request):
@@ -1401,6 +1582,11 @@ class ReticulumMeshChat:
         # send announce for audio call
         self.audio_call_manager.announce(app_data=self.config.display_name.get().encode("utf-8"))
 
+        # send announce for group chat servers
+        # todo allow groups to have independent announce schedules?
+        for group_chat_server in self.group_chat_servers:
+            group_chat_server.announce()
+
         # tell websocket clients we just announced
         await self.send_announced_to_websocket_clients()
 
@@ -1879,6 +2065,17 @@ class ReticulumMeshChat:
             "updated_at": announce.updated_at,
         }
 
+    # convert database group to a dictionary
+    def convert_db_group_to_dict(self, group: database.Group):
+        return {
+            "id": group.id,
+            "destination_hash": group.destination_hash,
+            "type": group.type,
+            "public_display_name": group.public_display_name,
+            "created_at": group.created_at,
+            "updated_at": group.updated_at,
+        }
+
     # convert database lxmf message to a dictionary
     def convert_db_lxmf_message_to_dict(self, db_lxmf_message: database.LxmfMessage):
 

src/backend/group_chat/group_chat_client.py

@@ -0,0 +1,97 @@
+import asyncio
+import json
+import time
+
+import RNS
+
+
+# a group chat client for interacting with group chat servers
+class GroupChatClient:
+
+    def __init__(self, group_destination_hash: bytes, user_identity: RNS.Identity):
+        self.group_destination_hash = group_destination_hash
+        self.user_identity = user_identity
+        self.link: RNS.Link | None = None
+
+    # connect to group chat server
+    async def _connect(self, timeout_after_seconds: int = 15):
+
+        # determine when to timeout connecting
+        timeout_after_seconds = time.time() + timeout_after_seconds
+
+        # check if we have a path to the destination
+        if not RNS.Transport.has_path(self.group_destination_hash):
+
+            # we don't have a path, so we need to request it
+            RNS.Transport.request_path(self.group_destination_hash)
+
+            # wait until we have a path, or give up after the configured timeout
+            while not RNS.Transport.has_path(self.group_destination_hash) and time.time() < timeout_after_seconds:
+                await asyncio.sleep(0.1)
+
+        # find destination identity from hash
+        destination_identity = RNS.Identity.recall(self.group_destination_hash)
+        if destination_identity is None:
+
+            # we have to bail out since we don't have the identity/path yet
+            raise Exception("Could not find path to destination. Try again later.")
+
+        # the group destination we will connect to
+        group_destination = RNS.Destination(
+            destination_identity,
+            RNS.Destination.OUT,
+            RNS.Destination.SINGLE,
+            "meshchat",
+            "group",
+        )
+
+        # create link to group destination
+        self.link = RNS.Link(group_destination)
+
+        # wait until we have established a link, or give up after the configured timeout
+        while self.link.status is not RNS.Link.ACTIVE and time.time() < timeout_after_seconds:
+            await asyncio.sleep(0.1)
+
+        # if we still haven't established a link, bail out
+        if self.link.status is not RNS.Link.ACTIVE:
+            raise Exception("Could not establish link to destination.")
+
+        # send our identity to be able to perform queries
+        self.link.identify(self.user_identity)
+
+    # makes a request over the link and returns an async response, or throws an exception on error
+    async def request(self, path: str, data: bytes | None = None):
+
+        # create future
+        loop = asyncio.get_running_loop()
+        future = loop.create_future()
+
+        # handle response
+        def response_callback(request_receipt):
+            loop.call_soon_threadsafe(future.set_result, request_receipt.response)
+
+        # handle failure
+        def failed_callback(error):
+            loop.call_soon_threadsafe(future.set_exception, error)
+
+        # if link is not active, connect now
+        if self.link is None or self.link.status != RNS.Link.ACTIVE:
+            await self._connect()
+
+        # send request over link
+        self.link.request(path, data=data, response_callback=response_callback, failed_callback=failed_callback)
+        return await future
+
+    # get info about group
+    async def get_info(self):
+        return await self.request("/api/v1/info")
+
+    # join group
+    async def join(self, display_name: str):
+        return await self.request("/api/v1/join", data=json.dumps({
+            "display_name": display_name,
+        }).encode("utf-8"))
+
+    # leave group
+    async def leave(self):
+        return await self.request("/api/v1/leave")

src/backend/group_chat/group_chat_server.py

@@ -0,0 +1,119 @@
+import json
+import RNS
+
+
+# the interface a data provider should implement for the group server to function
+# for example, you could store and retrieve this information from an sqlite database
+# however, an interface is provided to allow you to do this however you want
+class GroupDataProviderInterface:
+
+    # gets member count of a group
+    def get_member_count(self, group_destination_hash: bytes) -> int:
+        raise Exception("Not Implemented")
+
+    # check if a user is a member of a group
+    def is_member(self, group_destination_hash: bytes, identity_hash: bytes) -> bool:
+        raise Exception("Not Implemented")
+
+    # adds a member to a group
+    def add_member(self, group_destination_hash: bytes, identity_hash: bytes, display_name: str):
+        raise Exception("Not Implemented")
+
+    # removes a member from a group
+    def remove_member(self, group_destination_hash: bytes, identity_hash: bytes):
+        raise Exception("Not Implemented")
+
+
+# a group chat server than can handle membership management
+class GroupChatServer:
+
+    GROUP_TYPE_PUBLIC = "public"
+
+    def __init__(self, identity: RNS.Identity, data_provider: GroupDataProviderInterface, public_display_name: str, group_type: str):
+
+        self.identity = identity
+        self.data_provider = data_provider
+        self.public_display_name = public_display_name
+        self.group_type = group_type
+
+        # create group destination
+        self.group_destination = RNS.Destination(
+            self.identity,
+            RNS.Destination.IN,
+            RNS.Destination.SINGLE,
+            "meshchat",
+            "group",
+        )
+
+        # register request handlers
+        self.group_destination.register_request_handler(path="/api/v1/info", response_generator=self.on_received_api_v1_info_request, allow=RNS.Destination.ALLOW_ALL)
+        self.group_destination.register_request_handler(path="/api/v1/join", response_generator=self.on_received_api_v1_join_request, allow=RNS.Destination.ALLOW_ALL)
+        self.group_destination.register_request_handler(path="/api/v1/leave", response_generator=self.on_received_api_v1_leave_request, allow=RNS.Destination.ALLOW_ALL)
+
+    # announce group destination
+    def announce(self):
+        # todo add app data about group: public_display_name, members_count, group_type
+        self.group_destination.announce()
+        print("[GroupChatServer] announced destination: " + RNS.prettyhexrep(self.group_destination.hash))
+
+    # error response format
+    def success_response(self, message):
+        return json.dumps({
+            "success": message,
+        }).encode("utf-8")
+
+    # error response format
+    def error_response(self, message):
+        return json.dumps({
+            "error": message,
+        }).encode("utf-8")
+
+    # error response for requests that require an identity
+    def identity_not_provided_error_response(self):
+        return self.error_response("You must identity to to access this endpoint.")
+
+    # /api/v1/info
+    def on_received_api_v1_info_request(self, path, data, request_id, remote_identity, requested_at):
+        return json.dumps({
+            "group_type": self.group_type,
+            "public_display_name": self.public_display_name,
+            "members_count": self.data_provider.get_member_count(self.group_destination.hash),
+        }).encode("utf-8")
+
+    # /api/v1/join
+    def on_received_api_v1_join_request(self, path, data: bytes | None, request_id, remote_identity: RNS.Identity | None, requested_at):
+
+        # ensure user has identified
+        if remote_identity is None:
+            return self.identity_not_provided_error_response()
+
+        # attempt to parse data as json
+        display_name = None
+        if data is not None:
+            try:
+                json_data = json.loads(data.decode("utf-8"))
+                display_name = json_data["display_name"] or "Anonymous Peer"
+            except:
+                print("failed to parse request data as json")
+                pass
+
+        # ensure user is not already a member
+        if self.data_provider.is_member(self.group_destination.hash, remote_identity.hash):
+            return self.error_response("You are already a member of this group")
+
+        if self.group_type == self.GROUP_TYPE_PUBLIC:
+            self.data_provider.add_member(self.group_destination.hash, remote_identity.hash, display_name)
+            return self.success_response("You are now a member of this group")
+        else:
+            return self.error_response("Unsupported group type")
+
+    # /api/v1/leave
+    def on_received_api_v1_leave_request(self, path, data, request_id, remote_identity: RNS.Identity | None, requested_at):
+
+        # ensure user has identified
+        if remote_identity is None:
+            return self.identity_not_provided_error_response()
+
+        # remove member from group
+        self.data_provider.remove_member(self.group_destination.hash, remote_identity.hash)
+        return self.success_response("You are no longer a member of this group")