73 lines
2.5 KiB
Python
73 lines
2.5 KiB
Python
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"""Live service monitor — like `avahi-browse` without -t.
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Prints events as they happen:
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+ service appeared
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= service appeared and was resolved (address:port)
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- service disappeared
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With no --type it browses the DNS-SD meta-service
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(`_services._dns-sd._udp.local.`) to discover types dynamically and attaches a
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browser to each — the equivalent of `avahi-browse -a`.
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"""
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import time
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from zeroconf import Zeroconf, ServiceBrowser, ServiceListener
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class _EventListener(ServiceListener):
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def __init__(self, resolve: bool = True) -> None:
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self.resolve = resolve
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def add_service(self, zc: Zeroconf, type_: str, name: str) -> None: # noqa: N802
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line = f"+ {type_:<30} {name}"
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if self.resolve:
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info = zc.get_service_info(type_, name, timeout=1500)
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if info:
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addrs = ", ".join(info.parsed_addresses() or []) or "-"
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line = f"= {type_:<30} {name} {addrs}:{info.port}"
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print(line, flush=True)
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def update_service(self, zc: Zeroconf, type_: str, name: str) -> None: # noqa: N802
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return
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def remove_service(self, zc: Zeroconf, type_: str, name: str) -> None: # noqa: N802
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print(f"- {type_:<30} {name}", flush=True)
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class _TypeSpawner(ServiceListener):
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"""On discovering a new service TYPE, attach a browser for it."""
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def __init__(self, zc: Zeroconf, svc_listener: ServiceListener) -> None:
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self.zc = zc
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self.svc_listener = svc_listener
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self.browsers: dict[str, ServiceBrowser] = {}
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def add_service(self, zc: Zeroconf, type_: str, name: str) -> None: # noqa: N802
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# For the meta-service, `name` is the discovered type (e.g. _http._tcp.local.)
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if name not in self.browsers:
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self.browsers[name] = ServiceBrowser(zc, name, self.svc_listener)
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def update_service(self, *a) -> None: # noqa: N802
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return
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def remove_service(self, *a) -> None: # noqa: N802
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return
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def watch(service_type: str | None = None, resolve: bool = True) -> None:
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zc = Zeroconf()
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svc = _EventListener(resolve=resolve)
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try:
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if service_type:
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ServiceBrowser(zc, service_type, svc)
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else:
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ServiceBrowser(zc, "_services._dns-sd._udp.local.",
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_TypeSpawner(zc, svc))
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print("[mdns] watching — Ctrl+C to stop", flush=True)
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while True:
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time.sleep(1)
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except KeyboardInterrupt:
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pass
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finally:
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zc.close()
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