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package dnstap
import (
"context"
"time"
"github.com/coredns/coredns/plugin"
"github.com/coredns/coredns/plugin/dnstap/msg"
"github.com/coredns/coredns/plugin/pkg/replacer"
"github.com/coredns/coredns/request"
tap "github.com/dnstap/golang-dnstap"
"github.com/miekg/dns"
)
// Dnstap is the dnstap handler.
type Dnstap struct {
Next plugin.Handler
io tapper
repl replacer.Replacer
// IncludeRawMessage will include the raw DNS message into the dnstap messages if true.
IncludeRawMessage bool
Identity []byte
Version []byte
ExtraFormat string
}
// TapMessage sends the message m to the dnstap interface, without populating "Extra" field.
func (h Dnstap) TapMessage(m *tap.Message) {
if h.ExtraFormat == "" {
h.tapWithExtra(m, nil)
} else {
h.tapWithExtra(m, []byte(h.ExtraFormat))
}
}
// TapMessageWithMetadata sends the message m to the dnstap interface, with "Extra" field being populated.
func (h Dnstap) TapMessageWithMetadata(ctx context.Context, m *tap.Message, state request.Request) {
if h.ExtraFormat == "" {
h.tapWithExtra(m, nil)
return
}
extraStr := h.repl.Replace(ctx, state, nil, h.ExtraFormat)
h.tapWithExtra(m, []byte(extraStr))
}
func (h Dnstap) tapWithExtra(m *tap.Message, extra []byte) {
t := tap.Dnstap_MESSAGE
h.io.Dnstap(&tap.Dnstap{Type: &t, Message: m, Identity: h.Identity, Version: h.Version, Extra: extra})
}
func (h Dnstap) tapQuery(ctx context.Context, w dns.ResponseWriter, query *dns.Msg, queryTime time.Time) {
q := new(tap.Message)
msg.SetQueryTime(q, queryTime)
msg.SetQueryAddress(q, w.RemoteAddr())
if h.IncludeRawMessage {
buf, _ := query.Pack()
q.QueryMessage = buf
}
msg.SetType(q, tap.Message_CLIENT_QUERY)
state := request.Request{W: w, Req: query}
h.TapMessageWithMetadata(ctx, q, state)
}
// ServeDNS logs the client query and response to dnstap and passes the dnstap Context.
func (h Dnstap) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
rw := &ResponseWriter{
ResponseWriter: w,
Dnstap: h,
query: r,
ctx: ctx,
queryTime: time.Now(),
}
// The query tap message should be sent before sending the query to the
// forwarder. Otherwise, the tap messages will come out out of order.
h.tapQuery(ctx, w, r, rw.queryTime)
return plugin.NextOrFailure(h.Name(), h.Next, ctx, rw, r)
}
// Name implements the plugin.Plugin interface.
func (h Dnstap) Name() string { return "dnstap" }
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