Pull request: 3157 excessive ptrs

Merge in DNS/adguard-home from 3157-excessive-ptrs to master

Updates #3157.

Squashed commit of the following:

commit 6803988240dca2f147bb80a5b3f78d7749d2fa14
Author: Eugene Burkov <E.Burkov@AdGuard.COM>
Date:   Tue Apr 19 14:50:01 2022 +0300

    aghnet: and again

commit 1a7f4d1dbc8fd4d3ae620349917526a75fa71b47
Author: Eugene Burkov <E.Burkov@AdGuard.COM>
Date:   Tue Apr 19 14:49:20 2022 +0300

    aghnet: docs again

commit d88da1fc7135f3cd03aff10b02d9957c8ffdfd30
Author: Eugene Burkov <E.Burkov@AdGuard.COM>
Date:   Tue Apr 19 14:47:36 2022 +0300

    aghnet: imp docs

commit c45dbc7800e882c6c4110aab640c32b03046f89a
Author: Eugene Burkov <E.Burkov@AdGuard.COM>
Date:   Tue Apr 19 14:41:19 2022 +0300

    aghnet: keep alphabetical order

commit b61781785d096ef43f60fb4f1905a4ed3cdf7c68
Author: Eugene Burkov <E.Burkov@AdGuard.COM>
Date:   Tue Apr 19 13:50:56 2022 +0300

    aghnet: imp code quality

commit 578dbd71ed2f2089c69343d7d4bf8bbc29150ace
Author: Eugene Burkov <E.Burkov@AdGuard.COM>
Date:   Tue Apr 12 17:02:38 2022 +0300

    aghnet: imp arp container

CHANGELOG.md

@@ -87,10 +87,15 @@ In this release, the schema version has changed from 12 to 13.
 
 - Go 1.17 support.  v0.109.0 will require at least Go 1.18 to build.
 
+### Fixed
+
+- ARP tables refreshing process causing excessive PTR requests ([#3157]).
+
 [#1730]: https://github.com/AdguardTeam/AdGuardHome/issues/1730
 [#2993]: https://github.com/AdguardTeam/AdGuardHome/issues/2993
 [#3057]: https://github.com/AdguardTeam/AdGuardHome/issues/3057
 [#3142]: https://github.com/AdguardTeam/AdGuardHome/issues/3142
+[#3157]: https://github.com/AdguardTeam/AdGuardHome/issues/3157
 [#3367]: https://github.com/AdguardTeam/AdGuardHome/issues/3367
 [#3381]: https://github.com/AdguardTeam/AdGuardHome/issues/3381
 [#3503]: https://github.com/AdguardTeam/AdGuardHome/issues/3503

internal/aghnet/arpdb_bsd.go

@@ -13,19 +13,24 @@ import (
 	"github.com/AdguardTeam/golibs/netutil"
 )
 
-func newARPDB() *cmdARPDB {
+func newARPDB() (arp *cmdARPDB) {
 	return &cmdARPDB{
 		parse: parseArpA,
 		ns: &neighs{
 			mu: &sync.RWMutex{},
 			ns: make([]Neighbor, 0),
 		},
-		cmd:  "arp",
+		cmd: "arp",
-		args: []string{"-a"},
+		// Use -n flag to avoid resolving the hostnames of the neighbors.  By
+		// default ARP attempts to resolve the hostnames via DNS.  See man 8
+		// arp.
+		//
+		// See also https://github.com/AdguardTeam/AdGuardHome/issues/3157.
+		args: []string{"-a", "-n"},
 	}
 }
 
-// parseArpA parses the output of the "arp -a" command on macOS and FreeBSD.
+// parseArpA parses the output of the "arp -a -n" command on macOS and FreeBSD.
 // The expected input format:
 //
 //   host.name (192.168.0.1) at ff:ff:ff:ff:ff:ff on en0 ifscope [ethernet]

internal/aghnet/arpdb_linux.go

@@ -38,12 +38,17 @@ func newARPDB() (arp *arpdbs) {
 			fsys:     rootDirFS,
 			filename: "proc/net/arp",
 		},
-		// Then, try "arp -a".
+		// Then, try "arp -a -n".
 		&cmdARPDB{
 			parse: parseF,
 			ns:    ns,
 			cmd:   "arp",
-			args:  []string{"-a"},
+			// Use -n flag to avoid resolving the hostnames of the neighbors.
+			// By default ARP attempts to resolve the hostnames via DNS.  See
+			// man 8 arp.
+			//
+			// See also https://github.com/AdguardTeam/AdGuardHome/issues/3157.
+			args: []string{"-a", "-n"},
 		},
 		// Finally, try "ip neigh".
 		&cmdARPDB{
@@ -109,11 +114,11 @@ func (arp *fsysARPDB) Neighbors() (ns []Neighbor) {
 	return arp.ns.clone()
 }
 
-// parseArpAWrt parses the output of the "arp -a" command on OpenWrt.  The
+// parseArpAWrt parses the output of the "arp -a -n" command on OpenWrt.  The
 // expected input format:
 //
-//   IP address       HW type     Flags       HW address            Mask     Device
+//   IP address     HW type  Flags  HW address         Mask  Device
-//   192.168.11.98    0x1         0x2         5a:92:df:a9:7e:28     *        wan
+//   192.168.11.98  0x1      0x2    5a:92:df:a9:7e:28  *     wan
 //
 func parseArpAWrt(sc *bufio.Scanner, lenHint int) (ns []Neighbor) {
 	if !sc.Scan() {
@@ -153,8 +158,8 @@ func parseArpAWrt(sc *bufio.Scanner, lenHint int) (ns []Neighbor) {
 	return ns
 }
 
-// parseArpA parses the output of the "arp -a" command on Linux.  The expected
+// parseArpA parses the output of the "arp -a -n" command on Linux.  The
-// input format:
+// expected input format:
 //
 //   hostname (192.168.1.1) at ab:cd:ef:ab:cd:ef [ether] on enp0s3
 //

internal/aghnet/arpdb_openbsd.go

@@ -12,20 +12,25 @@ import (
 	"github.com/AdguardTeam/golibs/log"
 )
 
-func newARPDB() *cmdARPDB {
+func newARPDB() (arp *cmdARPDB) {
 	return &cmdARPDB{
 		parse: parseArpA,
 		ns: &neighs{
 			mu: &sync.RWMutex{},
 			ns: make([]Neighbor, 0),
 		},
-		cmd:  "arp",
+		cmd: "arp",
-		args: []string{"-a"},
+		// Use -n flag to avoid resolving the hostnames of the neighbors.  By
+		// default ARP attempts to resolve the hostnames via DNS.  See man 8
+		// arp.
+		//
+		// See also https://github.com/AdguardTeam/AdGuardHome/issues/3157.
+		args: []string{"-a", "-n"},
 	}
 }
 
-// parseArpA parses the output of the "arp -a" command on OpenBSD.  The expected
+// parseArpA parses the output of the "arp -a -n" command on OpenBSD.  The
-// input format:
+// expected input format:
 //
 //   Host        Ethernet Address  Netif Expire    Flags
 //   192.168.1.1 ab:cd:ef:ab:cd:ef   em0 19m59s

internal/aghnet/arpdb_windows.go

@@ -10,7 +10,7 @@ import (
 	"sync"
 )
 
-func newARPDB() *cmdARPDB {
+func newARPDB() (arp *cmdARPDB) {
 	return &cmdARPDB{
 		parse: parseArpA,
 		ns: &neighs{

internal/dnsforward/dns.go

@@ -135,7 +135,6 @@ func (s *Server) processRecursion(dctx *dnsContext) (rc resultCode) {
 		pctx.Res = s.genNXDomain(pctx.Req)
 
 		return resultCodeFinish
-
 	}
 
 	return resultCodeSuccess

internal/dnsforward/recursiondetector_test.go

@@ -83,7 +83,7 @@ func TestRecursionDetector_Suspect(t *testing.T) {
 	testCases := []struct {
 		name string
 		msg  dns.Msg
-		want bool
+		want int
 	}{{
 		name: "simple",
 		msg: dns.Msg{
@@ -95,24 +95,18 @@ func TestRecursionDetector_Suspect(t *testing.T) {
 				Qtype: dns.TypeA,
 			}},
 		},
-		want: true,
+		want: 1,
 	}, {
 		name: "unencumbered",
 		msg:  dns.Msg{},
-		want: false,
+		want: 0,
 	}}
 
 	for _, tc := range testCases {
 		t.Run(tc.name, func(t *testing.T) {
 			t.Cleanup(rd.clear)
-
 			rd.add(tc.msg)
-
+			assert.Equal(t, tc.want, rd.recentRequests.Stats().Count)
-			if tc.want {
-				assert.Equal(t, 1, rd.recentRequests.Stats().Count)
-			} else {
-				assert.Zero(t, rd.recentRequests.Stats().Count)
-			}
 		})
 	}
 }

internal/home/rdns.go

@@ -16,18 +16,17 @@ type RDNS struct {
 	exchanger dnsforward.RDNSExchanger
 	clients   *clientsContainer
 
-	// usePrivate is used to store the state of current private RDNS
+	// usePrivate is used to store the state of current private RDNS resolving
-	// resolving settings and to react to it's changes.
+	// settings and to react to it's changes.
 	usePrivate uint32
 
 	// ipCh used to pass client's IP to rDNS workerLoop.
 	ipCh chan net.IP
 
 	// ipCache caches the IP addresses to be resolved by rDNS.  The resolved
-	// address stays here while it's inside clients.  After leaving clients
+	// address stays here while it's inside clients.  After leaving clients the
-	// the address will be resolved once again.  If the address couldn't be
+	// address will be resolved once again.  If the address couldn't be
-	// resolved, cache prevents further attempts to resolve it for some
+	// resolved, cache prevents further attempts to resolve it for some time.
-	// time.
 	ipCache cache.Cache
 }