dns-suite.js/node_modules/native-dns-cache/README.md

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2017-01-14 02:04:27 +00:00
Cache
-----
If you perform a query on an A or AAAA type and it doesn't exist, the cache
will attempt to lookup a CNAME and then resolve that.
The constructor takes an optional object with the following properties:
* `store` -- implements the cache store model (optional, default MemoryStore)
Methods:
* `lookup(question, cb)` -- for a given question check the cache store for
existence
* `store(packet)` -- iterates over the resource records in a packet and sends
them to the cache store
* `purge()` -- clears the cache store of all entries
MemoryStore / Cache store model
-------------------------------
`MemoryStore(opts)` -- An in memory store based on a js object
Methods:
* `get(domain, key, cb)`
- `domain` is the holder under which keys will be applied,
`key` is the subdomain that is being queried for.
If you `get('example.com', 'www', cb)` you are really asking for `www.example.com`.
- `cb(err, results)` -- results is an object of types and array of answers
* `{ 1: [{address: '127.0.0.1', ttl: 300, type: 1, class: 1}] }`
* `set(domain, key, data, cb)`
- `domain` is the parent under which this key is stored.
`key` is the subdomain we are storing, `data` is an object of types with an array of answers.
* `set('example.com', 'www', {1: [{class:1, type:1, ttl:300, address:'127.0.0.1'}]}, cb)`
- `cb(err, data)` -- cb merely returns the data that was passed.
* `delete(domain[, key[, type]], cb)` -- delete all from a domain, a domain and key,
or a domain a key and a type.
Lookup
------
Is a mechanism that given a store performs the common resolution pattern.
Given `example.com` previous added to a store:
* `www.example.com CNAME foo.bar.example.com.`
* `*.example.com A 127.0.0.1`
A `Lookup(store, 'example.com', {name:'www.example.com', type:1}, cb)`
will resolve `www` to the CNAME and then search for `foo.bar.example.com` which
will return no results, and then search for `*.bar.example.com` which will also
return no results, and ultimately searches for `*.example.com` which will return
the desired record.
Callback will be called with `(err, results)` where results is an array suitable
for use in `Packet.answer`