57 lines
2.5 KiB
Markdown
57 lines
2.5 KiB
Markdown
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# mDNS Module
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| Since | Origin / Contributor | Maintainer | Source |
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| :----- | :-------------------- | :---------- | :------ |
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| 2016-02-24 | [Philip Gladstone](https://github.com/pjsg) | [Philip Gladstone](https://github.com/pjsg) | [mdns.c](../../app/modules/mdns.c)|
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[Multicast DNS](https://en.wikipedia.org/wiki/Multicast_DNS) is used as part of Bonjour / Zeroconf. This allows systems to identify themselves and the services that they provide on a local area network. Clients are then able to discover these systems and connect to them.
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!!! note
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This is a mDNS *server* module. If you are looking for a mDNS *client* for NodeMCU (i.e. to query mDNS) then [udaygin/nodemcu-mdns-client](https://github.com/udaygin/nodemcu-mdns-client) may be an option.
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## mdns.register()
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Register a hostname and start the mDNS service. If the service is already running, then it will be restarted with the new parameters.
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#### Syntax
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`mdns.register(hostname [, attributes])`
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#### Parameters
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- `hostname` The hostname for this device. Alphanumeric characters are best.
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- `attributes` A optional table of options. The keys must all be strings.
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The `attributes` contains two sorts of attributes — those with specific names, and those that are service specific. [RFC 6763](https://tools.ietf.org/html/rfc6763#page-13)
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defines how extra, service specific, attributes are encoded into the DNS. One example is that if the device supports printing, then the queue name can
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be specified as an additional attribute. This module supports up to 10 such attributes.
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The specific names are:
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- `port` The port number for the service. Default value is 80.
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- `service` The name of the service. Default value is 'http'.
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- `description` A short phrase (under 63 characters) describing the service. Default is the hostname.
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#### Returns
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`nil`
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#### Errors
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Various errors can be generated during argument validation. The NodeMCU must have an IP address at the time of the call, otherwise an error is thrown.
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#### Example
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mdns.register("fishtank", {hardware='NodeMCU'})
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Using `dns-sd` on macOS, you can see `fishtank.local` as providing the `_http._tcp` service. You can also browse directly to `fishtank.local`. In Safari you can get all the mDNS web pages as part of your bookmarks menu.
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mdns.register("fishtank", { description="Top Fishtank", service="http", port=80, location='Living Room' })
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## mdns.close()
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Shut down the mDNS service. This is not normally needed.
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#### Syntax
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`mdns.close()`
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#### Parameters
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none
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#### Returns
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`nil`
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