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// SPDX-License-Identifier: GPL-3.0-or-later
package dnsmasq
import (
"fmt"
"strconv"
"strings"
"github.com/miekg/dns"
)
func (d *Dnsmasq) collect() (map[string]int64, error) {
r, err := d.queryCacheStatistics()
if err != nil {
return nil, err
}
ms := make(map[string]int64)
if err = d.collectResponse(ms, r); err != nil {
return nil, err
}
return ms, nil
}
func (d *Dnsmasq) collectResponse(ms map[string]int64, resp *dns.Msg) error {
/*
;; flags: qr aa rd ra; QUERY: 7, ANSWER: 7, AUTHORITY: 0, ADDITIONAL: 0
;; QUESTION SECTION:
;cachesize.bind. CH TXT
;insertions.bind. CH TXT
;evictions.bind. CH TXT
;hits.bind. CH TXT
;misses.bind. CH TXT
;auth.bind. CH TXT
;servers.bind. CH TXT
;; ANSWER SECTION:
cachesize.bind. 0 CH TXT "150"
insertions.bind. 0 CH TXT "1"
evictions.bind. 0 CH TXT "0"
hits.bind. 0 CH TXT "176"
misses.bind. 0 CH TXT "4"
auth.bind. 0 CH TXT "0"
servers.bind. 0 CH TXT "10.0.0.1#53 0 0" "1.1.1.1#53 4 3" "1.0.0.1#53 3 0"
*/
for _, a := range resp.Answer {
txt, ok := a.(*dns.TXT)
if !ok {
continue
}
idx := strings.IndexByte(txt.Hdr.Name, '.')
if idx == -1 {
continue
}
switch name := txt.Hdr.Name[:idx]; name {
case "servers":
for _, entry := range txt.Txt {
parts := strings.Fields(entry)
if len(parts) != 3 {
return fmt.Errorf("parse %s (%s): unexpected format", txt.Hdr.Name, entry)
}
queries, err := strconv.ParseFloat(parts[1], 64)
if err != nil {
return fmt.Errorf("parse '%s' (%s): %v", txt.Hdr.Name, entry, err)
}
failedQueries, err := strconv.ParseFloat(parts[2], 64)
if err != nil {
return fmt.Errorf("parse '%s' (%s): %v", txt.Hdr.Name, entry, err)
}
ms["queries"] += int64(queries)
ms["failed_queries"] += int64(failedQueries)
}
case "cachesize", "insertions", "evictions", "hits", "misses", "auth":
if len(txt.Txt) != 1 {
return fmt.Errorf("parse '%s' (%v): unexpected format", txt.Hdr.Name, txt.Txt)
}
v, err := strconv.ParseFloat(txt.Txt[0], 64)
if err != nil {
return fmt.Errorf("parse '%s' (%s): %v", txt.Hdr.Name, txt.Txt[0], err)
}
ms[name] = int64(v)
}
}
return nil
}
func (d *Dnsmasq) queryCacheStatistics() (*dns.Msg, error) {
msg := &dns.Msg{
MsgHdr: dns.MsgHdr{
Id: dns.Id(),
RecursionDesired: true,
},
Question: []dns.Question{
{Name: "cachesize.bind.", Qtype: dns.TypeTXT, Qclass: dns.ClassCHAOS},
{Name: "insertions.bind.", Qtype: dns.TypeTXT, Qclass: dns.ClassCHAOS},
{Name: "evictions.bind.", Qtype: dns.TypeTXT, Qclass: dns.ClassCHAOS},
{Name: "hits.bind.", Qtype: dns.TypeTXT, Qclass: dns.ClassCHAOS},
{Name: "misses.bind.", Qtype: dns.TypeTXT, Qclass: dns.ClassCHAOS},
// TODO: collect auth.bind if available
// auth.bind query is only supported if dnsmasq has been built
// to support running as an authoritative name server. See https://github.com/netdata/netdata/issues/13766
//{Name: "auth.bind.", Qtype: dns.TypeTXT, Qclass: dns.ClassCHAOS},
{Name: "servers.bind.", Qtype: dns.TypeTXT, Qclass: dns.ClassCHAOS},
},
}
r, _, err := d.dnsClient.Exchange(msg, d.Address)
if err != nil {
return nil, err
}
if r == nil {
return nil, fmt.Errorf("'%s' returned an empty response", d.Address)
}
if r.Rcode != dns.RcodeSuccess {
s := dns.RcodeToString[r.Rcode]
return nil, fmt.Errorf("'%s' returned '%s' (%d) response code", d.Address, s, r.Rcode)
}
return r, nil
}
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