Replace magic number with named constants

libp2p/relay/circuit_v2/config.py

@@ -9,6 +9,7 @@ from dataclasses import (
     dataclass,
     field,
 )
+from enum import Flag, auto
 
 from libp2p.peer.peerinfo import (
     PeerInfo,
@@ -18,29 +19,95 @@ from .resources import (
     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
+    # Role configuration (bit-flags)
-    enable_hop: bool = False  # Whether to act as a relay (hop)
+    roles: RelayRole = RelayRole.STOP | RelayRole.CLIENT
-    enable_stop: bool = True  # Whether to accept relayed connections (stop)
-    enable_client: bool = True  # Whether to use relays for dialing
 
     # Resource limits
     limits: RelayLimits | None = None
 
     # Discovery configuration
     bootstrap_relays: list[PeerInfo] = field(default_factory=list)
-    min_relays: int = 3
+    min_relays: int = DEFAULT_MIN_RELAYS
-    max_relays: int = 20
+    max_relays: int = DEFAULT_MAX_RELAYS
-    discovery_interval: int = 300  # seconds
+    discovery_interval: int = DEFAULT_DISCOVERY_INTERVAL
 
     # Connection configuration
-    reservation_ttl: int = 3600  # seconds
+    reservation_ttl: int = DEFAULT_RESERVATION_TTL
-    max_circuit_duration: int = 3600  # seconds
+    max_circuit_duration: int = DEFAULT_MAX_CIRCUIT_DURATION
-    max_circuit_bytes: int = 1024 * 1024 * 1024  # 1GB
+    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."""
@@ -48,8 +115,8 @@ class RelayConfig:
             self.limits = RelayLimits(
                 duration=self.max_circuit_duration,
                 data=self.max_circuit_bytes,
-                max_circuit_conns=8,
+                max_circuit_conns=DEFAULT_MAX_CIRCUIT_CONNS,
-                max_reservations=4,
+                max_reservations=DEFAULT_MAX_RESERVATIONS,
             )
 
 
@@ -58,20 +125,20 @@ class HopConfig:
     """Configuration specific to relay (hop) nodes."""
 
     # Resource limits per IP
-    max_reservations_per_ip: int = 8
+    max_reservations_per_ip: int = MAX_RESERVATIONS_PER_IP
-    max_circuits_per_ip: int = 16
+    max_circuits_per_ip: int = MAX_CIRCUITS_PER_IP
 
     # Rate limiting
-    reservation_rate_per_ip: int = 4  # per minute
+    reservation_rate_per_ip: int = RESERVATION_RATE_PER_IP
-    circuit_rate_per_ip: int = 8  # per minute
+    circuit_rate_per_ip: int = CIRCUIT_RATE_PER_IP
 
     # Resource quotas
-    max_circuits_total: int = 64
+    max_circuits_total: int = MAX_CIRCUITS_TOTAL
-    max_reservations_total: int = 32
+    max_reservations_total: int = MAX_RESERVATIONS_TOTAL
 
     # Bandwidth limits
-    max_bandwidth_per_circuit: int = 1024 * 1024  # 1MB/s
+    max_bandwidth_per_circuit: int = MAX_BANDWIDTH_PER_CIRCUIT
-    max_bandwidth_total: int = 10 * 1024 * 1024  # 10MB/s
+    max_bandwidth_total: int = MAX_BANDWIDTH_TOTAL
 
 
 @dataclass
@@ -79,14 +146,14 @@ class ClientConfig:
     """Configuration specific to relay clients."""
 
     # Relay selection
-    min_relay_score: float = 0.5
+    min_relay_score: float = MIN_RELAY_SCORE
-    max_relay_latency: float = 1.0  # seconds
+    max_relay_latency: float = MAX_RELAY_LATENCY
 
     # Auto-relay settings
-    enable_auto_relay: bool = True
+    enable_auto_relay: bool = ENABLE_AUTO_RELAY
-    auto_relay_timeout: int = 30  # seconds
+    auto_relay_timeout: int = AUTO_RELAY_TIMEOUT
-    max_auto_relay_attempts: int = 3
+    max_auto_relay_attempts: int = MAX_AUTO_RELAY_ATTEMPTS
 
     # Reservation management
-    reservation_refresh_threshold: float = 0.8  # Refresh at 80% of TTL
+    reservation_refresh_threshold: float = RESERVATION_REFRESH_THRESHOLD
-    max_concurrent_reservations: int = 2
+    max_concurrent_reservations: int = MAX_CONCURRENT_RESERVATIONS

libp2p/relay/circuit_v2/dcutr.py

@@ -39,6 +39,12 @@ from libp2p.tools.async_service import (
     Service,
 )
 
+from .config import (
+    DIAL_TIMEOUT,
+    STREAM_READ_TIMEOUT,
+    STREAM_WRITE_TIMEOUT,
+)
+
 logger = logging.getLogger(__name__)
 
 # Protocol ID for DCUtR
@@ -47,11 +53,6 @@ PROTOCOL_ID = TProtocol("/libp2p/dcutr")
 # 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 @@ from libp2p.tools.async_service import (
     Service,
 )
 
+from .config import (
+    DEFAULT_DISCOVERY_INTERVAL as CFG_DISCOVERY_INTERVAL,
+)
 from .pb.circuit_pb2 import (
     HopMessage,
 )
@@ -43,10 +46,11 @@ from .protocol_buffer import (
 
 logger = logging.getLogger("libp2p.relay.circuit_v2.discovery")
 
-# Constants
+# Constants (single-source-of-truth)
-MAX_RELAYS_TO_TRACK = 10
+DEFAULT_DISCOVERY_INTERVAL = CFG_DISCOVERY_INTERVAL
-DEFAULT_DISCOVERY_INTERVAL = 60  # seconds
+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 @@ class RelayDiscovery(Service):
                     self._discovered_relays[peer_id].last_seen = time.time()
                     continue
 
-                # Check if peer supports the relay protocol
+                # Don't wait too long for protocol info
-                with trio.move_on_after(5):  # 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 @@ class RelayDiscovery(Service):
 
         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/protocol.py

@@ -5,6 +5,7 @@ This module implements the Circuit Relay v2 protocol as specified in:
 https://github.com/libp2p/specs/blob/master/relay/circuit-v2.md
 """
 
+from enum import Enum, auto
 import logging
 import time
 from typing import (
@@ -37,6 +38,15 @@ from libp2p.tools.async_service import (
     Service,
 )
 
+from .config import (
+    DEFAULT_MAX_CIRCUIT_BYTES,
+    DEFAULT_MAX_CIRCUIT_CONNS,
+    DEFAULT_MAX_CIRCUIT_DURATION,
+    DEFAULT_MAX_RESERVATIONS,
+    STREAM_CLOSE_TIMEOUT,
+    STREAM_READ_TIMEOUT,
+    STREAM_WRITE_TIMEOUT,
+)
 from .pb.circuit_pb2 import (
     HopMessage,
     Limit,
@@ -58,18 +68,21 @@ logger = logging.getLogger("libp2p.relay.circuit_v2")
 PROTOCOL_ID = TProtocol("/libp2p/circuit/relay/2.0.0")
 STOP_PROTOCOL_ID = TProtocol("/libp2p/circuit/relay/2.0.0/stop")
 
-# Default limits for relay resources
+
+# Direction enum for data piping
+class Pipe(Enum):
+    SRC_TO_DST = auto()
+    DST_TO_SRC = auto()
+
+
+# Default limits for relay resources (single source of truth)
 DEFAULT_RELAY_LIMITS = RelayLimits(
-    duration=60 * 60,  # 1 hour
+    duration=DEFAULT_MAX_CIRCUIT_DURATION,
-    data=1024 * 1024 * 1024,  # 1GB
+    data=DEFAULT_MAX_CIRCUIT_BYTES,
-    max_circuit_conns=8,
+    max_circuit_conns=DEFAULT_MAX_CIRCUIT_CONNS,
-    max_reservations=4,
+    max_reservations=DEFAULT_MAX_RESERVATIONS,
 )
 
-# Stream operation timeouts
-STREAM_READ_TIMEOUT = 15  # seconds
-STREAM_WRITE_TIMEOUT = 15  # seconds
-STREAM_CLOSE_TIMEOUT = 10  # seconds
 MAX_READ_RETRIES = 5  # Maximum number of read retries
 
 
@@ -458,8 +471,20 @@ class CircuitV2Protocol(Service):
 
             # Start relaying data
             async with trio.open_nursery() as nursery:
-                nursery.start_soon(self._relay_data, src_stream, stream, peer_id)
+                nursery.start_soon(
-                nursery.start_soon(self._relay_data, stream, src_stream, peer_id)
+                    self._relay_data,
+                    src_stream,
+                    stream,
+                    peer_id,
+                    Pipe.SRC_TO_DST,
+                )
+                nursery.start_soon(
+                    self._relay_data,
+                    stream,
+                    src_stream,
+                    peer_id,
+                    Pipe.DST_TO_SRC,
+                )
 
         except trio.TooSlowError:
             logger.error("Timeout reading from stop stream")
@@ -648,8 +673,20 @@ class CircuitV2Protocol(Service):
 
             # Start relaying data
             async with trio.open_nursery() as nursery:
-                nursery.start_soon(self._relay_data, stream, dst_stream, peer_id)
+                nursery.start_soon(
-                nursery.start_soon(self._relay_data, dst_stream, stream, peer_id)
+                    self._relay_data,
+                    stream,
+                    dst_stream,
+                    peer_id,
+                    Pipe.SRC_TO_DST,
+                )
+                nursery.start_soon(
+                    self._relay_data,
+                    dst_stream,
+                    stream,
+                    peer_id,
+                    Pipe.DST_TO_SRC,
+                )
 
         except (trio.TooSlowError, ConnectionError) as e:
             logger.error("Error establishing relay connection: %s", str(e))
@@ -685,6 +722,7 @@ class CircuitV2Protocol(Service):
         src_stream: INetStream,
         dst_stream: INetStream,
         peer_id: ID,
+        direction: Pipe,
     ) -> None:
         """
         Relay data between two streams.
@@ -698,13 +736,16 @@ class CircuitV2Protocol(Service):
         peer_id : ID
             ID of the peer being relayed
 
+        direction : Pipe
+            Direction of data flow (``Pipe.SRC_TO_DST`` or ``Pipe.DST_TO_SRC``)
+
         """
         try:
             while True:
                 # Read data with retries
                 data = await self._read_stream_with_retry(src_stream)
                 if not data:
-                    logger.info("Source stream closed/reset")
+                    logger.info("%s closed/reset", direction.name)
                     break
 
                 # Write data with timeout
@@ -712,10 +753,10 @@ class CircuitV2Protocol(Service):
                     with trio.fail_after(STREAM_WRITE_TIMEOUT):
                         await dst_stream.write(data)
                 except trio.TooSlowError:
-                    logger.error("Timeout writing to destination stream")
+                    logger.error("Timeout writing in %s", direction.name)
                     break
                 except Exception as e:
-                    logger.error("Error writing to destination stream: %s", str(e))
+                    logger.error("Error writing in %s: %s", direction.name, str(e))
                     break
 
                 # Update resource usage

libp2p/relay/circuit_v2/resources.py

@@ -8,6 +8,7 @@ including reservations and connection limits.
 from dataclasses import (
     dataclass,
 )
+from enum import Enum, auto
 import hashlib
 import os
 import time
@@ -19,6 +20,18 @@ from libp2p.peer.id import (
 # Import the protobuf definitions
 from .pb.circuit_pb2 import Reservation as PbReservation
 
+RANDOM_BYTES_LENGTH = 16  # 128 bits of randomness
+TIMESTAMP_MULTIPLIER = 1000000  # To convert seconds to microseconds
+
+
+# Reservation status enum
+class ReservationStatus(Enum):
+    """Lifecycle status of a relay reservation."""
+
+    ACTIVE = auto()
+    EXPIRED = auto()
+    REJECTED = auto()
+
 
 @dataclass
 class RelayLimits:
@@ -68,8 +81,8 @@ class Reservation:
         # - Peer ID to bind it to the specific peer
         # - Timestamp for uniqueness
         # - Hash everything for a fixed size output
-        random_bytes = os.urandom(16)  # 128 bits of randomness
+        random_bytes = os.urandom(RANDOM_BYTES_LENGTH)
-        timestamp = str(int(self.created_at * 1000000)).encode()
+        timestamp = str(int(self.created_at * TIMESTAMP_MULTIPLIER)).encode()
         peer_bytes = self.peer_id.to_bytes()
 
         # Combine all elements and hash them
@@ -84,6 +97,15 @@ class Reservation:
         """Check if the reservation has expired."""
         return time.time() > self.expires_at
 
+    # Expose a friendly status enum --------------------------------------
+
+    @property
+    def status(self) -> ReservationStatus:
+        """Return the current status as a ``ReservationStatus`` enum."""
+        return (
+            ReservationStatus.EXPIRED if self.is_expired() else ReservationStatus.ACTIVE
+        )
+
     def can_accept_connection(self) -> bool:
         """Check if a new connection can be accepted."""
         return (