First Build alpha 0.1

app/services/port_manager.py

@@ -0,0 +1,110 @@
+"""UDP port allocation service for NetBird relay/STUN ports.
+
+Manages the range starting at relay_base_port (default 3478). Each customer
+gets one unique UDP port. The manager checks both the database and the OS
+to avoid collisions.
+"""
+
+import logging
+import socket
+from typing import Optional
+
+from sqlalchemy.orm import Session
+
+from app.models import Deployment
+
+logger = logging.getLogger(__name__)
+
+
+def _is_udp_port_in_use(port: int) -> bool:
+    """Check whether a UDP port is currently bound on the host.
+
+    Args:
+        port: UDP port number to probe.
+
+    Returns:
+        True if the port is in use.
+    """
+    sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
+    try:
+        sock.bind(("0.0.0.0", port))
+        return False
+    except OSError:
+        return True
+    finally:
+        sock.close()
+
+
+def get_allocated_ports(db: Session) -> set[int]:
+    """Return the set of relay UDP ports already assigned in the database.
+
+    Args:
+        db: Active SQLAlchemy session.
+
+    Returns:
+        Set of port numbers.
+    """
+    rows = db.query(Deployment.relay_udp_port).all()
+    return {r[0] for r in rows}
+
+
+def allocate_port(db: Session, base_port: int = 3478, max_ports: int = 100) -> int:
+    """Find and return the next available relay UDP port.
+
+    Scans from *base_port* to *base_port + max_ports - 1*, skipping ports
+    that are either already in the database or currently bound on the host.
+
+    Args:
+        db: Active SQLAlchemy session.
+        base_port: Start of the port range.
+        max_ports: Number of ports in the range.
+
+    Returns:
+        An available port number.
+
+    Raises:
+        RuntimeError: If no port in the range is available.
+    """
+    allocated = get_allocated_ports(db)
+    for port in range(base_port, base_port + max_ports):
+        if port in allocated:
+            continue
+        if _is_udp_port_in_use(port):
+            logger.warning("Port %d is in use on the host, skipping.", port)
+            continue
+        logger.info("Allocated relay UDP port %d.", port)
+        return port
+
+    raise RuntimeError(
+        f"No available relay ports in range {base_port}-{base_port + max_ports - 1}. "
+        "All 100 ports are allocated."
+    )
+
+
+def release_port(db: Session, port: int) -> None:
+    """Mark a port as released (informational logging only).
+
+    The actual release happens when the Deployment row is deleted. This
+    helper exists for explicit logging in rollback scenarios.
+
+    Args:
+        db: Active SQLAlchemy session.
+        port: The port to release.
+    """
+    logger.info("Released relay UDP port %d.", port)
+
+
+def validate_port_available(db: Session, port: int) -> bool:
+    """Check if a specific port is available both in DB and on the host.
+
+    Args:
+        db: Active SQLAlchemy session.
+        port: Port number to check.
+
+    Returns:
+        True if the port is available.
+    """
+    allocated = get_allocated_ports(db)
+    if port in allocated:
+        return False
+    return not _is_udp_port_in_use(port)