Create a WHOIS server from scratch

Internet Data & Research
4

This helped a lot last year. I enhanced the server.py script (e.g. to indicate missing data): https://blog.shimps.org/blogpost544-whois-h-localhost

import argparse
import asyncio
import maxminddb
import ipaddress
SEPARATOR = b"\r\n"
class Handler:
    def __init__(self, database):
        self.reader = maxminddb.open_database(database)
    async def handle(self, reader, writer):
        data = await reader.readuntil(SEPARATOR)
        # Convert bytes to UTF-8 and lookup data in the MMDB.
        ip = data.split(SEPARATOR)[0].decode()
        info , prefix = self.reader.get_with_prefix_len(ip)
        bgp = ipaddress.ip_network(f"{ip}/{prefix}", strict=False)
        writer.write(f"route: {bgp}".encode() + SEPARATOR)
        # Output one key/value pair per line.
        if info:
            for k, v in info.items():
                writer.write(f"{k}: {v}".encode() + SEPARATOR)
            writer.write(f"dbstatus: ok - data found".encode() + SEPARATOR)
        else:
            writer.write(f"dbstatus: warning - no data available".encode() + SEPARATOR)
        await writer.drain()
        # Close the connection.
        writer.close()
        await writer.wait_closed()
async def main():
    parser = argparse.ArgumentParser()
    parser.add_argument("database")
    parser.add_argument("--host", default="localhost")
    parser.add_argument("--port", default=43, type=int)
    args = parser.parse_args()
    handler = Handler(args.database)
    server = await asyncio.start_server(handler.handle, args.host, args.port)
    await server.serve_forever()
if __name__ == "__main__":
    asyncio.run(main())

Maybe it is useful for someone else.