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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) {
mx := make(map[string]int64)
if err := d.collectCacheStatistics(mx); err != nil {
return nil, err
}
return mx, nil
}
func (d *Dnsmasq) collectCacheStatistics(mx map[string]int64) 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"
*/
questions := []string{
"servers.bind.",
"cachesize.bind.",
"insertions.bind.",
"evictions.bind.",
"hits.bind.",
"misses.bind.",
// 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
//"auth.bind.",
}
for _, q := range questions {
resp, err := d.query(q)
if err != nil {
return err
}
for _, a := range resp.Answer {
txt, ok := a.(*dns.TXT)
if !ok {
continue
}
idx := strings.IndexByte(txt.Hdr.Name, '.')
if idx == -1 {
continue
}
name := txt.Hdr.Name[:idx]
switch 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)
}
mx["queries"] += int64(queries)
mx["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)
}
mx[name] = int64(v)
}
}
}
return nil
}
func (d *Dnsmasq) query(question string) (*dns.Msg, error) {
msg := &dns.Msg{
MsgHdr: dns.MsgHdr{
Id: dns.Id(),
RecursionDesired: true,
},
Question: []dns.Question{
{Name: question, 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' question '%s', returned an empty response", d.Address, question)
}
if r.Rcode != dns.RcodeSuccess {
s := dns.RcodeToString[r.Rcode]
return nil, fmt.Errorf("'%s' question '%s' returned '%s' (%d) response code", d.Address, question, s, r.Rcode)
}
return r, nil
}
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