1 files changed, 126 insertions, 0 deletions
diff --git a/src/go/collectors/go.d.plugin/modules/dnsmasq/collect.go b/src/go/collectors/go.d.plugin/modules/dnsmasq/collect.go
new file mode 100644
index 000000000..2561688d7
--- /dev/null
+++ b/src/go/collectors/go.d.plugin/modules/dnsmasq/collect.go
@@ -0,0 +1,126 @@
+// 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
+}