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directory_server.handshake_handler

directory_server.handshake_handler

Handshake protocol handler for peer authentication and validation.

Implements Single Responsibility Principle: only handles handshakes.

Classes

HandshakeError

Bases: Exception

Source code in directory_server/src/directory_server/handshake_handler.py
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class HandshakeError(Exception):
    pass

HandshakeHandler

Source code in directory_server/src/directory_server/handshake_handler.py
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class HandshakeHandler:
    def __init__(
        self,
        network: NetworkType,
        server_nick: str,
        motd: str,
        neutrino_compat: bool = False,
        nick_auth_mode: NickAuthMode = NickAuthMode.DISABLED,
        nick_auth_directory_id: str | None = None,
    ):
        self.network = network
        self.server_nick = server_nick
        self.motd = motd
        self.neutrino_compat = neutrino_compat
        self.nick_auth_mode = nick_auth_mode
        self.nick_auth_directory_id = nick_auth_directory_id

    @property
    def advertises_nick_auth(self) -> bool:
        return self.nick_auth_mode is not NickAuthMode.DISABLED and bool(
            self.nick_auth_directory_id
        )

    def negotiates_nick_auth(self, peer: PeerInfo) -> bool:
        return self.advertises_nick_auth and peer.features.get(FEATURE_NICK_AUTH) is True

    def process_handshake(self, handshake_data: str, peer_location: str) -> tuple[PeerInfo, dict]:
        try:
            hs = json.loads(handshake_data)

            app_name = hs.get("app-name")
            is_directory = hs.get("directory", False)
            proto_ver = hs.get("proto-ver")
            features = hs.get("features", {})
            # Debug: Log received features for troubleshooting feature propagation
            if features:
                logger.debug(f"Handshake features from {hs.get('nick', 'unknown')}: {features}")
            location_string = hs.get("location-string")
            nick = hs.get("nick")
            network_str = hs.get("network")

            if not all([app_name, proto_ver, nick, network_str]):
                raise HandshakeError("Missing required handshake fields")

            if app_name.lower() != "joinmarket":
                raise HandshakeError(f"Invalid app name: {app_name}")

            if is_directory:
                raise HandshakeError("Directory nodes not accepted as clients")

            if not (JM_VERSION_MIN <= proto_ver <= JM_VERSION):
                raise HandshakeError(
                    f"Protocol version {proto_ver} not in supported range [{JM_VERSION_MIN}, {JM_VERSION}]"
                )

            peer_network = self._parse_network(network_str)
            if peer_network != self.network:
                raise HandshakeError(f"Network mismatch: {network_str} != {self.network.value}")

            onion_address, port = self._parse_location(location_string)

            # Determine negotiated version (highest both support)
            negotiated_version = min(proto_ver, JM_VERSION)

            # Check if peer supports Neutrino-compatible UTXO metadata
            peer_neutrino_compat = peer_supports_neutrino_compat(hs)

            peer_info = PeerInfo(
                nick=nick,
                onion_address=onion_address,
                port=port,
                status=PeerStatus.CONNECTED,
                is_directory=False,
                network=peer_network,
                features=features,
                protocol_version=negotiated_version,
                neutrino_compat=peer_neutrino_compat,
            )

            # Build our feature set - always include peerlist_features and ping
            server_features: set[str] = {FEATURE_PEERLIST_FEATURES, FEATURE_PING}
            if self.neutrino_compat:
                server_features.add(FEATURE_NEUTRINO_COMPAT)
            if self.advertises_nick_auth:
                server_features.add(FEATURE_NICK_AUTH)
            feature_set = FeatureSet(features=server_features)

            accepted = not (
                self.nick_auth_mode is NickAuthMode.REQUIRE_VERIFIED
                and not self.negotiates_nick_auth(peer_info)
            )

            response = create_handshake_response(
                nick=self.server_nick,
                network=self.network.value,
                accepted=accepted,
                motd=self.motd if accepted else "Rejected: verified nick authentication required",
                features=feature_set,
            )

            if accepted:
                logger.info(
                    f"Handshake accepted: {nick} from {peer_network.value} "
                    f"at {peer_info.location_string} "
                    f"(v{negotiated_version}, neutrino={peer_neutrino_compat})"
                )
            else:
                logger.info(f"Handshake rejected by nick authentication policy: {nick}")

            return (peer_info, response)

        except (json.JSONDecodeError, KeyError, ValueError) as e:
            logger.warning(f"Invalid handshake: {e}")
            raise HandshakeError(f"Invalid handshake format: {e}") from e

    def _parse_network(self, network_str: str) -> NetworkType:
        try:
            return NetworkType(network_str.lower())
        except ValueError as e:
            raise HandshakeError(f"Invalid network: {network_str}") from e

    def _parse_location(self, location: str) -> tuple[str, int]:
        if location == NOT_SERVING_ONION_HOSTNAME:
            return (NOT_SERVING_ONION_HOSTNAME, -1)

        try:
            if not location or ":" not in location:
                logger.warning(f"Incomplete location string: {location}, defaulting to not serving")
                return (NOT_SERVING_ONION_HOSTNAME, -1)

            host, port_str = location.split(":")
            port = int(port_str)
            if port <= 0 or port > 65535:
                raise ValueError("Invalid port")
            return (host, port)
        except (ValueError, AttributeError) as e:
            logger.warning(f"Invalid location string: {location}, defaulting to not serving: {e}")
            return (NOT_SERVING_ONION_HOSTNAME, -1)

    def create_rejection_response(self, reason: str) -> dict:
        return create_handshake_response(
            nick=self.server_nick,
            network=self.network.value,
            accepted=False,
            motd=f"Rejected: {reason}",
        )
Attributes
advertises_nick_auth: bool property
motd = motd instance-attribute
network = network instance-attribute
neutrino_compat = neutrino_compat instance-attribute
nick_auth_directory_id = nick_auth_directory_id instance-attribute
nick_auth_mode = nick_auth_mode instance-attribute
server_nick = server_nick instance-attribute
Methods:
__init__(network: NetworkType, server_nick: str, motd: str, neutrino_compat: bool = False, nick_auth_mode: NickAuthMode = NickAuthMode.DISABLED, nick_auth_directory_id: str | None = None)
Source code in directory_server/src/directory_server/handshake_handler.py
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def __init__(
    self,
    network: NetworkType,
    server_nick: str,
    motd: str,
    neutrino_compat: bool = False,
    nick_auth_mode: NickAuthMode = NickAuthMode.DISABLED,
    nick_auth_directory_id: str | None = None,
):
    self.network = network
    self.server_nick = server_nick
    self.motd = motd
    self.neutrino_compat = neutrino_compat
    self.nick_auth_mode = nick_auth_mode
    self.nick_auth_directory_id = nick_auth_directory_id
create_rejection_response(reason: str) -> dict
Source code in directory_server/src/directory_server/handshake_handler.py
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def create_rejection_response(self, reason: str) -> dict:
    return create_handshake_response(
        nick=self.server_nick,
        network=self.network.value,
        accepted=False,
        motd=f"Rejected: {reason}",
    )
negotiates_nick_auth(peer: PeerInfo) -> bool
Source code in directory_server/src/directory_server/handshake_handler.py
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def negotiates_nick_auth(self, peer: PeerInfo) -> bool:
    return self.advertises_nick_auth and peer.features.get(FEATURE_NICK_AUTH) is True
process_handshake(handshake_data: str, peer_location: str) -> tuple[PeerInfo, dict]
Source code in directory_server/src/directory_server/handshake_handler.py
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def process_handshake(self, handshake_data: str, peer_location: str) -> tuple[PeerInfo, dict]:
    try:
        hs = json.loads(handshake_data)

        app_name = hs.get("app-name")
        is_directory = hs.get("directory", False)
        proto_ver = hs.get("proto-ver")
        features = hs.get("features", {})
        # Debug: Log received features for troubleshooting feature propagation
        if features:
            logger.debug(f"Handshake features from {hs.get('nick', 'unknown')}: {features}")
        location_string = hs.get("location-string")
        nick = hs.get("nick")
        network_str = hs.get("network")

        if not all([app_name, proto_ver, nick, network_str]):
            raise HandshakeError("Missing required handshake fields")

        if app_name.lower() != "joinmarket":
            raise HandshakeError(f"Invalid app name: {app_name}")

        if is_directory:
            raise HandshakeError("Directory nodes not accepted as clients")

        if not (JM_VERSION_MIN <= proto_ver <= JM_VERSION):
            raise HandshakeError(
                f"Protocol version {proto_ver} not in supported range [{JM_VERSION_MIN}, {JM_VERSION}]"
            )

        peer_network = self._parse_network(network_str)
        if peer_network != self.network:
            raise HandshakeError(f"Network mismatch: {network_str} != {self.network.value}")

        onion_address, port = self._parse_location(location_string)

        # Determine negotiated version (highest both support)
        negotiated_version = min(proto_ver, JM_VERSION)

        # Check if peer supports Neutrino-compatible UTXO metadata
        peer_neutrino_compat = peer_supports_neutrino_compat(hs)

        peer_info = PeerInfo(
            nick=nick,
            onion_address=onion_address,
            port=port,
            status=PeerStatus.CONNECTED,
            is_directory=False,
            network=peer_network,
            features=features,
            protocol_version=negotiated_version,
            neutrino_compat=peer_neutrino_compat,
        )

        # Build our feature set - always include peerlist_features and ping
        server_features: set[str] = {FEATURE_PEERLIST_FEATURES, FEATURE_PING}
        if self.neutrino_compat:
            server_features.add(FEATURE_NEUTRINO_COMPAT)
        if self.advertises_nick_auth:
            server_features.add(FEATURE_NICK_AUTH)
        feature_set = FeatureSet(features=server_features)

        accepted = not (
            self.nick_auth_mode is NickAuthMode.REQUIRE_VERIFIED
            and not self.negotiates_nick_auth(peer_info)
        )

        response = create_handshake_response(
            nick=self.server_nick,
            network=self.network.value,
            accepted=accepted,
            motd=self.motd if accepted else "Rejected: verified nick authentication required",
            features=feature_set,
        )

        if accepted:
            logger.info(
                f"Handshake accepted: {nick} from {peer_network.value} "
                f"at {peer_info.location_string} "
                f"(v{negotiated_version}, neutrino={peer_neutrino_compat})"
            )
        else:
            logger.info(f"Handshake rejected by nick authentication policy: {nick}")

        return (peer_info, response)

    except (json.JSONDecodeError, KeyError, ValueError) as e:
        logger.warning(f"Invalid handshake: {e}")
        raise HandshakeError(f"Invalid handshake format: {e}") from e