Persist GNS transport configuration

server/config.py

@@ -20,6 +20,25 @@ MAX_PLAYERS_HARD_LIMIT = 256
 DEFAULT_ADMIN_PORT = 7779
 
 
+
+def _parse_bool(value: Any, *, field_name: str, default: bool = False) -> bool:
+    if value is None:
+        return default
+    if isinstance(value, bool):
+        return value
+    if isinstance(value, int) and not isinstance(value, bool) and value in (0, 1):
+        return bool(value)
+    if isinstance(value, str):
+        text = value.strip().lower()
+        if text in {"1", "true", "yes", "on"}:
+            return True
+        if text in {"0", "false", "no", "off", ""}:
+            return False
+    raise ValueError(
+        f"{field_name} must be a boolean or one of true/false, yes/no, on/off, 1/0"
+    )
+
+
 @dataclass
 class Config:
     """Server configuration model."""
@@ -30,6 +49,8 @@ class Config:
     max_players: int = 16
     log_verbosity: str = "info"
     admin_port: int = DEFAULT_ADMIN_PORT
+    enable_gns_transport: bool = False
+    gns_bridge_path: str | None = None
 
     def to_dict(self) -> dict[str, Any]:
         """Convert config to dictionary."""
@@ -41,6 +62,8 @@ class Config:
             "max_players": self.max_players,
             "log_verbosity": self.log_verbosity,
             "admin_port": self.admin_port,
+            "enable_gns_transport": self.enable_gns_transport,
+            "gns_bridge_path": self.gns_bridge_path,
         }
 
     @classmethod
@@ -53,6 +76,20 @@ class Config:
         except (TypeError, ValueError) as error:
             raise ValueError(f"Invalid numeric config field: {error}") from error
 
+        enable_gns_transport = _parse_bool(
+            data.get("enable_gns_transport"),
+            field_name="enable_gns_transport",
+            default=False,
+        )
+        raw_bridge_path = data.get("gns_bridge_path")
+        if raw_bridge_path is None:
+            gns_bridge_path = None
+        elif isinstance(raw_bridge_path, str):
+            normalized_bridge_path = raw_bridge_path.strip()
+            gns_bridge_path = normalized_bridge_path or None
+        else:
+            raise ValueError("gns_bridge_path must be a string or null")
+
         return cls(
             host=str(data.get("host", "0.0.0.0")),
             port=port,
@@ -61,6 +98,8 @@ class Config:
             max_players=max_players,
             log_verbosity=str(data.get("log_verbosity", "info")),
             admin_port=admin_port,
+            enable_gns_transport=enable_gns_transport,
+            gns_bridge_path=gns_bridge_path,
         )
 
 
@@ -145,6 +184,18 @@ def _is_valid_bind_host(host: str) -> bool:
         return False
 
 
+def _is_valid_gns_bind_host(host: str) -> bool:
+    """Return True for the strict IPv4 bind form used by the native GNS bridge."""
+    text = host.strip()
+    if not text:
+        return False
+    try:
+        socket.inet_pton(socket.AF_INET, text)
+        return True
+    except OSError:
+        return False
+
+
 def validate_config(config: Config) -> tuple[bool, list[str]]:
     """
     Validate configuration values.
@@ -163,6 +214,11 @@ def validate_config(config: Config) -> tuple[bool, list[str]]:
         errors.append(
             f"host '{config.host}' is not a valid IPv4 address or resolvable hostname"
         )
+    elif config.enable_gns_transport and not _is_valid_gns_bind_host(str(config.host)):
+        errors.append(
+            "enable_gns_transport requires host to be an explicit IPv4 bind address "
+            "such as 0.0.0.0 or 127.0.0.1"
+        )
 
     if config.port < 1 or config.port > 65535:
         errors.append(f"port must be 1-65535, got {config.port}")