Module plugin_mdns 

The mdns.advertise and mdns.browse plugin methods: DNS-SD on the LAN, done by the host on a plugin’s behalf.

A sandboxed plugin cannot run an mDNS responder itself. Every plugin unit carries SocketBindDeny=any, and systemd’s bind filter matches every port under any, the ephemeral port 0 included, so an in-process daemon fails at its first bind (the signal socket) before it could reach the multicast port. The host is not sandboxed and publishes the record with the same library and the same SRV-target rule core’s own _ados._tcp advert uses: the system hostname as crate::reach::mdns_hostname resolves it, the one name avahi answers for.

An advert is owned by the plugin connection that made it and is withdrawn when that connection ends, so a record never outlives the process serving the port it names. Its port must be one of the plugin’s declared listen_ports: a plugin can only advertise what the sandbox lets it serve. The service types core publishes itself (RESERVED_SERVICE_TYPES) are refused, so a plugin cannot impersonate a node’s pairing record or a ground station’s receiver. Browsing any well-formed type is allowed.

The types are the wire shape: the host decodes the request and serializes the reply with them, and the SDK does the reverse, so the two cannot drift.

Structs

AdvertiseRequest

An mdns.advertise request.

Advertised

The record the host published.

BrowseReply

What one browse found.

BrowseRequest

An mdns.browse request.

DiscoveredService

One resolved service instance.

Constants

ADVERTISE_CAPABILITY

The capability mdns.advertise is gated on: advertising a port is offering it to the network, which is what network.listen grants.

ADVERTISE_METHOD

The advertise method’s wire name.

BROWSE_CAPABILITY

The capability mdns.browse is gated on: a browse finds peers to connect out to.

BROWSE_DEFAULT_TIMEOUT_MS

The browse window when the request names none.

BROWSE_MAX_RESULTS

The most services one browse returns.

BROWSE_MAX_TIMEOUT_MS

The longest browse window a request may ask for.

BROWSE_METHOD

The browse method’s wire name.

BROWSE_MIN_TIMEOUT_MS

The shortest browse window: one mDNS query round trip.

RESERVED_SERVICE_TYPES

The service types core publishes. A plugin may browse them but never advertise one: _ados._tcp is every node’s pairing record (the control front publishes it on every profile and interface) and _ados-receiver._tcp is the ground-station mesh receiver.

TXT_MAX_ENTRIES

The most TXT entries one advert may carry.

TXT_MAX_KEY_LEN

The longest TXT key.

TXT_MAX_VALUE_LEN

The longest TXT value, in bytes.

Functions

advertisable_service_type

The service type a plugin may advertise, canonical: TCP, well formed, and not one core publishes.

normalize_service_type

The canonical _<name>._<tcp|udp> form of a service type (a trailing .local. or .local is stripped), or why it is not one.

validate_txt

Check a TXT record against the size and key rules: at most TXT_MAX_ENTRIES entries, keys of 1..=TXT_MAX_KEY_LEN printable ASCII characters without =, values of at most TXT_MAX_VALUE_LEN bytes.