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b3b8a7e4b7
* plugin/dnstap: various cleanups A recent issue made me look into this plugin, I suspect various other cleanups (hopefully deletion of code) can be made as well Remove identical functions ToClientQuery etc, and just use tap.Message as the base type in plugin. Keep msg/ for a few helper functions that may proof useful. This remove the whole test directory as we will just check the things we are interested in which gives much better feedback and keeps that code closer together. tapwr dir is also not needed, writer_test.go was just duplicating the tests already done. This moves writer.go to the top directory. Make the only user of dnstap, the forward plugin, use the newer code also remove the test, a better test there would be a full e2e test to see the correct thing happens. Cleanup the Tapper interface and move it to dnstapio where it belongs, remove higher level interfaces that are not used. This remove dnstap.Tapper and dnstap.IORoutines. Use the standard mechanism for getting access to a plugin and remove shuffling the plugin into the context. Signed-off-by: Miek Gieben <miek@miek.nl> * use opts to get the correct proto Signed-off-by: Miek Gieben <miek@miek.nl> * Various fixes Signed-off-by: Miek Gieben <miek@miek.nl> * Remove bad addr test, as dnstap is only called from within coredns where these fields have been preparsed Signed-off-by: Miek Gieben <miek@miek.nl> * dnstap: remove saving the error all these fields have been preparsed, no need for dnstap to be pedantic and check (and save!) this error again. Simplifies it a bit more. Signed-off-by: Miek Gieben <miek@miek.nl> * Update plugin/forward/dnstap.go Co-authored-by: Ruslan Drozhdzh <30860269+rdrozhdzh@users.noreply.github.com> * Code review Signed-off-by: Miek Gieben <miek@miek.nl> * add back in preferUDP Signed-off-by: Miek Gieben <miek@miek.nl> * nit Signed-off-by: Miek Gieben <miek@miek.nl> Co-authored-by: Ruslan Drozhdzh <30860269+rdrozhdzh@users.noreply.github.com>
105 lines
2.5 KiB
Markdown
105 lines
2.5 KiB
Markdown
# dnstap
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## Name
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*dnstap* - enables logging to dnstap.
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## Description
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dnstap is a flexible, structured binary log format for DNS software; see https://dnstap.info. With this
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plugin you make CoreDNS output dnstap logging.
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Note that there is an internal buffer, so expect at least 13 requests before the server sends its
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dnstap messages to the socket.
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## Syntax
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~~~ txt
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dnstap SOCKET [full]
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~~~
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* **SOCKET** is the socket path supplied to the dnstap command line tool.
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* `full` to include the wire-format DNS message.
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## Examples
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Log information about client requests and responses to */tmp/dnstap.sock*.
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~~~ txt
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dnstap /tmp/dnstap.sock
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~~~
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Log information including the wire-format DNS message about client requests and responses to */tmp/dnstap.sock*.
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~~~ txt
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dnstap unix:///tmp/dnstap.sock full
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~~~
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Log to a remote endpoint.
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~~~ txt
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dnstap tcp://127.0.0.1:6000 full
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~~~
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## Command Line Tool
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Dnstap has a command line tool that can be used to inspect the logging. The tool can be found
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at Github: <https://github.com/dnstap/golang-dnstap>. It's written in Go.
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The following command listens on the given socket and decodes messages to stdout.
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~~~ sh
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$ dnstap -u /tmp/dnstap.sock
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~~~
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The following command listens on the given socket and saves message payloads to a binary dnstap-format log file.
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~~~ sh
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$ dnstap -u /tmp/dnstap.sock -w /tmp/test.dnstap
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~~~
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Listen for dnstap messages on port 6000.
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~~~ sh
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$ dnstap -l 127.0.0.1:6000
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~~~
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## Using Dnstap in your plugin
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In your setup function, check to see if the *dnstap* plugin is loaded:
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~~~ go
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c.OnStartup(func() error {
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if taph := dnsserver.GetConfig(c).Handler("dnstap"); taph != nil {
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if tapPlugin, ok := taph.(dnstap.Dnstap); ok {
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f.tapPlugin = &tapPlugin
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}
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}
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return nil
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})
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~~~
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And then in your plugin:
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~~~ go
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func (x RandomPlugin) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
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if tapPlugin != nil {
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q := new(msg.Msg)
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msg.SetQueryTime(q, time.Now())
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msg.SetQueryAddress(q, w.RemoteAddr())
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if tapPlugin.IncludeRawMessage {
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buf, _ := r.Pack() // r has been seen packed/unpacked before, this should not fail
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q.QueryMessage = buf
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}
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msg.SetType(q, tap.Message_CLIENT_QUERY)
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tapPlugin.TapMessage(q)
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}
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// ...
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}
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~~~
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## See Also
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The website [dnstap.info](https://dnstap.info) has info on the dnstap protocol.
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The *forward* plugin's `dnstap.go` uses dnstap to tap messages sent to an upstream.
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