06_resolve_relay_ipv4.py

"""
Resolve relay hostnames to current IPv4 addresses.

Use this when your client needs an IP literal instead of a domain — for
example, when the runtime resolver is unreliable, or when a load balancer
in front of your code can't do DNS lookups for upstream proxies.

WARNING: relay IPs change. Do not pin them in long-running config. Re-resolve
periodically (once per hour or on connection error) so you follow ProxyShard's
infrastructure changes.
"""
import socket

from proxyshard import RELAY_HOSTS


def resolve_all(host: str) -> list[str]:
    """Return every A record for `host`. Some relays are behind multiple IPs."""
    try:
        _, _, addrs = socket.gethostbyname_ex(host)
        return addrs
    except socket.gaierror as e:
        raise RuntimeError(f"DNS lookup failed for {host}: {e}") from e


def main() -> None:
    for region, host in RELAY_HOSTS.items():
        try:
            ips = resolve_all(host)
        except RuntimeError as e:
            print(f"  {host}  →  ERROR: {e}")
            continue
        print(f"  {host:30}  →  {', '.join(ips)}")


if __name__ == "__main__":
    main()