Refactor: Replace magic numbers with named constants and enums for clarity and maintainability

libp2p/relay/circuit_v2/config.py

@@ -9,6 +9,7 @@
     dataclass,
     field,
 )
+from enum import Flag, auto
 
 from libp2p.peer.peerinfo import (
     PeerInfo,
@@ -18,38 +19,104 @@
     RelayLimits,
 )
 
+DEFAULT_MIN_RELAYS = 3
+DEFAULT_MAX_RELAYS = 20
+DEFAULT_DISCOVERY_INTERVAL = 300  # seconds
+DEFAULT_RESERVATION_TTL = 3600  # seconds
+DEFAULT_MAX_CIRCUIT_DURATION = 3600  # seconds
+DEFAULT_MAX_CIRCUIT_BYTES = 1024 * 1024 * 1024  # 1GB
+
+DEFAULT_MAX_CIRCUIT_CONNS = 8
+DEFAULT_MAX_RESERVATIONS = 4
+
+MAX_RESERVATIONS_PER_IP = 8
+MAX_CIRCUITS_PER_IP = 16
+RESERVATION_RATE_PER_IP = 4  # per minute
+CIRCUIT_RATE_PER_IP = 8  # per minute
+MAX_CIRCUITS_TOTAL = 64
+MAX_RESERVATIONS_TOTAL = 32
+MAX_BANDWIDTH_PER_CIRCUIT = 1024 * 1024  # 1MB/s
+MAX_BANDWIDTH_TOTAL = 10 * 1024 * 1024  # 10MB/s
+
+MIN_RELAY_SCORE = 0.5
+MAX_RELAY_LATENCY = 1.0  # seconds
+ENABLE_AUTO_RELAY = True
+AUTO_RELAY_TIMEOUT = 30  # seconds
+MAX_AUTO_RELAY_ATTEMPTS = 3
+RESERVATION_REFRESH_THRESHOLD = 0.8  # Refresh at 80% of TTL
+MAX_CONCURRENT_RESERVATIONS = 2
+
+# Shared timeout constants (used across modules)
+STREAM_READ_TIMEOUT = 15  # seconds
+STREAM_WRITE_TIMEOUT = 15  # seconds
+STREAM_CLOSE_TIMEOUT = 10  # seconds
+DIAL_TIMEOUT = 10  # seconds
+
+# NAT reachability timeout
+REACHABILITY_TIMEOUT = 10  # seconds
+
+# Relay roles enum -----------------------------------------------------------
+
+
+class RelayRole(Flag):
+    """
+    Bit-flag enum that captures the three possible relay capabilities.
+
+    A node can combine multiple roles using bit-wise OR, for example::
+
+        RelayRole.HOP | RelayRole.STOP
+    """
+
+    HOP = auto()  # Act as a relay for others ("hop")
+    STOP = auto()  # Accept relayed connections ("stop")
+    CLIENT = auto()  # Dial through existing relays ("client")
+
 
-@dataclass
 class RelayConfig:
     """Configuration for Circuit Relay v2."""
 
-    # Role configuration
-    enable_hop: bool = False  # Whether to act as a relay (hop)
-    enable_stop: bool = True  # Whether to accept relayed connections (stop)
-    enable_client: bool = True  # Whether to use relays for dialing
+    # Role configuration (bit-flags)
+    roles: RelayRole = RelayRole.STOP | RelayRole.CLIENT
 
     # Resource limits
     limits: RelayLimits | None = None
 
     # Discovery configuration
     bootstrap_relays: list[PeerInfo] = field(default_factory=list)
-    min_relays: int = 3
-    max_relays: int = 20
-    discovery_interval: int = 300  # seconds
+    min_relays: int = DEFAULT_MIN_RELAYS
+    max_relays: int = DEFAULT_MAX_RELAYS
+    discovery_interval: int = DEFAULT_DISCOVERY_INTERVAL
 
     # Connection configuration
-    reservation_ttl: int = 3600  # seconds
-    max_circuit_duration: int = 3600  # seconds
-    max_circuit_bytes: int = 1024 * 1024 * 1024  # 1GB
+    reservation_ttl: int = DEFAULT_RESERVATION_TTL
+    max_circuit_duration: int = DEFAULT_MAX_CIRCUIT_DURATION
+    max_circuit_bytes: int = DEFAULT_MAX_CIRCUIT_BYTES
+
+    # ---------------------------------------------------------------------
+    # Backwards-compat boolean helpers.  Existing code that still accesses
+    # ``cfg.enable_hop, cfg.enable_stop, cfg.enable_client`` will continue to work.
+    # ---------------------------------------------------------------------
+
+    @property
+    def enable_hop(self) -> bool:  # pragma: no cover – helper
+        return bool(self.roles & RelayRole.HOP)
+
+    @property
+    def enable_stop(self) -> bool:  # pragma: no cover – helper
+        return bool(self.roles & RelayRole.STOP)
+
+    @property
+    def enable_client(self) -> bool:  # pragma: no cover – helper
+        return bool(self.roles & RelayRole.CLIENT)
 
     def __post_init__(self) -> None:
         """Initialize default values."""
         if self.limits is None:
             self.limits = RelayLimits(
                 duration=self.max_circuit_duration,
                 data=self.max_circuit_bytes,
-                max_circuit_conns=8,
-                max_reservations=4,
+                max_circuit_conns=DEFAULT_MAX_CIRCUIT_CONNS,
+                max_reservations=DEFAULT_MAX_RESERVATIONS,
             )
 
 
@@ -58,35 +125,35 @@ class HopConfig:
     """Configuration specific to relay (hop) nodes."""
 
     # Resource limits per IP
-    max_reservations_per_ip: int = 8
-    max_circuits_per_ip: int = 16
+    max_reservations_per_ip: int = MAX_RESERVATIONS_PER_IP
+    max_circuits_per_ip: int = MAX_CIRCUITS_PER_IP
 
     # Rate limiting
-    reservation_rate_per_ip: int = 4  # per minute
-    circuit_rate_per_ip: int = 8  # per minute
+    reservation_rate_per_ip: int = RESERVATION_RATE_PER_IP
+    circuit_rate_per_ip: int = CIRCUIT_RATE_PER_IP
 
     # Resource quotas
-    max_circuits_total: int = 64
-    max_reservations_total: int = 32
+    max_circuits_total: int = MAX_CIRCUITS_TOTAL
+    max_reservations_total: int = MAX_RESERVATIONS_TOTAL
 
     # Bandwidth limits
-    max_bandwidth_per_circuit: int = 1024 * 1024  # 1MB/s
-    max_bandwidth_total: int = 10 * 1024 * 1024  # 10MB/s
+    max_bandwidth_per_circuit: int = MAX_BANDWIDTH_PER_CIRCUIT
+    max_bandwidth_total: int = MAX_BANDWIDTH_TOTAL
 
 
 @dataclass
 class ClientConfig:
     """Configuration specific to relay clients."""
 
     # Relay selection
-    min_relay_score: float = 0.5
-    max_relay_latency: float = 1.0  # seconds
+    min_relay_score: float = MIN_RELAY_SCORE
+    max_relay_latency: float = MAX_RELAY_LATENCY
 
     # Auto-relay settings
-    enable_auto_relay: bool = True
-    auto_relay_timeout: int = 30  # seconds
-    max_auto_relay_attempts: int = 3
+    enable_auto_relay: bool = ENABLE_AUTO_RELAY
+    auto_relay_timeout: int = AUTO_RELAY_TIMEOUT
+    max_auto_relay_attempts: int = MAX_AUTO_RELAY_ATTEMPTS
 
     # Reservation management
-    reservation_refresh_threshold: float = 0.8  # Refresh at 80% of TTL
-    max_concurrent_reservations: int = 2
+    reservation_refresh_threshold: float = RESERVATION_REFRESH_THRESHOLD
+    max_concurrent_reservations: int = MAX_CONCURRENT_RESERVATIONS

libp2p/relay/circuit_v2/dcutr.py

@@ -39,6 +39,12 @@
     Service,
 )
 
+from .config import (
+    DIAL_TIMEOUT,
+    STREAM_READ_TIMEOUT,
+    STREAM_WRITE_TIMEOUT,
+)
+
 logger = logging.getLogger(__name__)
 
 # Protocol ID for DCUtR
@@ -47,11 +53,6 @@
 # Maximum message size for DCUtR (4KiB as per spec)
 MAX_MESSAGE_SIZE = 4 * 1024
 
-# Timeouts
-STREAM_READ_TIMEOUT = 30  # seconds
-STREAM_WRITE_TIMEOUT = 30  # seconds
-DIAL_TIMEOUT = 10  # seconds
-
 # Maximum number of hole punch attempts per peer
 MAX_HOLE_PUNCH_ATTEMPTS = 5
 

libp2p/relay/circuit_v2/discovery.py

@@ -31,6 +31,9 @@
     Service,
 )
 
+from .config import (
+    DEFAULT_DISCOVERY_INTERVAL as CFG_DISCOVERY_INTERVAL,
+)
 from .pb.circuit_pb2 import (
     HopMessage,
 )
@@ -43,10 +46,11 @@
 
 logger = logging.getLogger("libp2p.relay.circuit_v2.discovery")
 
-# Constants
-MAX_RELAYS_TO_TRACK = 10
-DEFAULT_DISCOVERY_INTERVAL = 60  # seconds
+# Constants (single-source-of-truth)
+DEFAULT_DISCOVERY_INTERVAL = CFG_DISCOVERY_INTERVAL
+MAX_RELAYS_TO_TRACK = 10  # Still discovery-specific
 STREAM_TIMEOUT = 10  # seconds
+PEER_PROTOCOL_TIMEOUT = 5  # seconds
 
 
 # Extended interfaces for type checking
@@ -165,20 +169,20 @@ async def discover_relays(self) -> None:
                     self._discovered_relays[peer_id].last_seen = time.time()
                     continue
 
-                # Check if peer supports the relay protocol
-                with trio.move_on_after(5):  # Don't wait too long for protocol info
+                # Don't wait too long for protocol info
+                with trio.move_on_after(PEER_PROTOCOL_TIMEOUT):
                     if await self._supports_relay_protocol(peer_id):
                         await self._add_relay(peer_id)
 
             # Limit number of relays we track
-            if len(self._discovered_relays) > self.max_relays:
+            if len(self._discovered_relays) > MAX_RELAYS_TO_TRACK:
                 # Sort by last seen time and keep only the most recent ones
                 sorted_relays = sorted(
                     self._discovered_relays.items(),
                     key=lambda x: x[1].last_seen,
                     reverse=True,
                 )
-                to_remove = sorted_relays[self.max_relays :]
+                to_remove = sorted_relays[MAX_RELAYS_TO_TRACK:]
                 for peer_id, _ in to_remove:
                     del self._discovered_relays[peer_id]
 
@@ -463,7 +467,7 @@ async def _cleanup_expired(self) -> None:
 
         for peer_id, relay_info in self._discovered_relays.items():
             # Check if relay hasn't been seen in a while (3x discovery interval)
-            if now - relay_info.last_seen > self.discovery_interval * 3:
+            if now - relay_info.last_seen > DEFAULT_DISCOVERY_INTERVAL * 3:
                 to_remove.append(peer_id)
                 continue
 

libp2p/relay/circuit_v2/nat.py

@@ -19,10 +19,9 @@
     ID,
 )
 
-logger = logging.getLogger("libp2p.relay.circuit_v2.nat")
+# REACHABILITY_TIMEOUT now imported from config
 
-# Timeout for reachability checks
-REACHABILITY_TIMEOUT = 10  # seconds
+logger = logging.getLogger("libp2p.relay.circuit_v2.nat")
 
 # Define private IP ranges
 PRIVATE_IP_RANGES = [