58 lines
2.1 KiB
Markdown
58 lines
2.1 KiB
Markdown
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Cache
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-----
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If you perform a query on an A or AAAA type and it doesn't exist, the cache
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will attempt to lookup a CNAME and then resolve that.
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The constructor takes an optional object with the following properties:
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* `store` -- implements the cache store model (optional, default MemoryStore)
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Methods:
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* `lookup(question, cb)` -- for a given question check the cache store for
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existence
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* `store(packet)` -- iterates over the resource records in a packet and sends
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them to the cache store
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* `purge()` -- clears the cache store of all entries
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MemoryStore / Cache store model
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-------------------------------
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`MemoryStore(opts)` -- An in memory store based on a js object
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Methods:
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* `get(domain, key, cb)`
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- `domain` is the holder under which keys will be applied,
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`key` is the subdomain that is being queried for.
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If you `get('example.com', 'www', cb)` you are really asking for `www.example.com`.
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- `cb(err, results)` -- results is an object of types and array of answers
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* `{ 1: [{address: '127.0.0.1', ttl: 300, type: 1, class: 1}] }`
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* `set(domain, key, data, cb)`
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- `domain` is the parent under which this key is stored.
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`key` is the subdomain we are storing, `data` is an object of types with an array of answers.
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* `set('example.com', 'www', {1: [{class:1, type:1, ttl:300, address:'127.0.0.1'}]}, cb)`
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- `cb(err, data)` -- cb merely returns the data that was passed.
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* `delete(domain[, key[, type]], cb)` -- delete all from a domain, a domain and key,
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or a domain a key and a type.
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Lookup
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------
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Is a mechanism that given a store performs the common resolution pattern.
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Given `example.com` previous added to a store:
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* `www.example.com CNAME foo.bar.example.com.`
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* `*.example.com A 127.0.0.1`
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A `Lookup(store, 'example.com', {name:'www.example.com', type:1}, cb)`
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will resolve `www` to the CNAME and then search for `foo.bar.example.com` which
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will return no results, and then search for `*.bar.example.com` which will also
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return no results, and ultimately searches for `*.example.com` which will return
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the desired record.
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Callback will be called with `(err, results)` where results is an array suitable
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for use in `Packet.answer`
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