Pull request: home: mv local domain name to dhcp setts

Closes #3367.

Squashed commit of the following:

commit e2cabcac2d91af24b9e5f4ac8f78daf5e8d339b9
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Tue Jan 25 19:35:31 2022 +0300

    home: imp test, skip dhcp test on windows

commit e58053f11e081630ad4e8d1e77a7a74226029db0
Merge: ff2fe87d 0b72bcc5
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Tue Jan 25 19:10:25 2022 +0300

    Merge branch 'master' into 3367-dhcp-local-domain-name

commit ff2fe87d8cab12e60d045be636e366e392d6d96f
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Thu Dec 30 20:55:34 2021 +0300

    home: mv local domain name to dhcp setts

internal/dhcpd/dhcpd.go

@@ -119,23 +119,28 @@ func (l *Lease) UnmarshalJSON(data []byte) (err error) {
 	return nil
 }
 
-// ServerConfig - DHCP server configuration
-// field ordering is important -- yaml fields will mirror ordering from here
+// ServerConfig is the configuration for the DHCP server.  The order of YAML
+// fields is important, since the YAML configuration file follows it.
 type ServerConfig struct {
-	Enabled       bool   `yaml:"enabled"`
-	InterfaceName string `yaml:"interface_name"`
-
-	Conf4 V4ServerConf `yaml:"dhcpv4"`
-	Conf6 V6ServerConf `yaml:"dhcpv6"`
-
-	WorkDir    string `yaml:"-"`
-	DBFilePath string `yaml:"-"` // path to DB file
-
 	// Called when the configuration is changed by HTTP request
 	ConfigModified func() `yaml:"-"`
 
 	// Register an HTTP handler
 	HTTPRegister func(string, string, func(http.ResponseWriter, *http.Request)) `yaml:"-"`
+
+	Enabled       bool   `yaml:"enabled"`
+	InterfaceName string `yaml:"interface_name"`
+
+	// LocalDomainName is the domain name used for DHCP hosts.  For example,
+	// a DHCP client with the hostname "myhost" can be addressed as "myhost.lan"
+	// when LocalDomainName is "lan".
+	LocalDomainName string `yaml:"local_domain_name"`
+
+	Conf4 V4ServerConf `yaml:"dhcpv4"`
+	Conf6 V6ServerConf `yaml:"dhcpv6"`
+
+	WorkDir    string `yaml:"-"`
+	DBFilePath string `yaml:"-"`
 }
 
 // OnLeaseChangedT is a callback for lease changes.
@@ -156,7 +161,9 @@ type Server struct {
 	srv4 DHCPServer
 	srv6 DHCPServer
 
-	conf ServerConfig
+	// TODO(a.garipov): Either create a separate type for the internal config or
+	// just put the config values into Server.
+	conf *ServerConfig
 
 	// Called when the leases DB is modified
 	onLeaseChanged []OnLeaseChangedT
@@ -181,14 +188,21 @@ type ServerInterface interface {
 }
 
 // Create - create object
-func Create(conf ServerConfig) (s *Server, err error) {
-	s = &Server{}
+func Create(conf *ServerConfig) (s *Server, err error) {
+	s = &Server{
+		conf: &ServerConfig{
+			ConfigModified: conf.ConfigModified,
 
-	s.conf.Enabled = conf.Enabled
-	s.conf.InterfaceName = conf.InterfaceName
-	s.conf.HTTPRegister = conf.HTTPRegister
-	s.conf.ConfigModified = conf.ConfigModified
-	s.conf.DBFilePath = filepath.Join(conf.WorkDir, dbFilename)
+			HTTPRegister: conf.HTTPRegister,
+
+			Enabled:       conf.Enabled,
+			InterfaceName: conf.InterfaceName,
+
+			LocalDomainName: conf.LocalDomainName,
+
+			DBFilePath: filepath.Join(conf.WorkDir, dbFilename),
+		},
+	}
 
 	if !webHandlersRegistered && s.conf.HTTPRegister != nil {
 		if runtime.GOOS == "windows" {
@@ -305,6 +319,7 @@ func (s *Server) notify(flags int) {
 func (s *Server) WriteDiskConfig(c *ServerConfig) {
 	c.Enabled = s.conf.Enabled
 	c.InterfaceName = s.conf.InterfaceName
+	c.LocalDomainName = s.conf.LocalDomainName
 	s.srv4.WriteDiskConfig4(&c.Conf4)
 	s.srv6.WriteDiskConfig6(&c.Conf6)
 }

internal/dhcpd/dhcpd_test.go

@@ -27,7 +27,7 @@ func testNotify(flags uint32) {
 func TestDB(t *testing.T) {
 	var err error
 	s := Server{
-		conf: ServerConfig{
+		conf: &ServerConfig{
 			DBFilePath: dbFilename,
 		},
 	}
@@ -140,27 +140,27 @@ func TestNormalizeLeases(t *testing.T) {
 func TestV4Server_badRange(t *testing.T) {
 	testCases := []struct {
 		name       string
+		wantErrMsg string
 		gatewayIP  net.IP
 		subnetMask net.IP
-		wantErrMsg string
 	}{{
-		name:       "gateway_in_range",
-		gatewayIP:  net.IP{192, 168, 10, 120},
-		subnetMask: net.IP{255, 255, 255, 0},
+		name: "gateway_in_range",
 		wantErrMsg: "dhcpv4: gateway ip 192.168.10.120 in the ip range: " +
 			"192.168.10.20-192.168.10.200",
+		gatewayIP:  net.IP{192, 168, 10, 120},
+		subnetMask: net.IP{255, 255, 255, 0},
 	}, {
-		name:       "outside_range_start",
-		gatewayIP:  net.IP{192, 168, 10, 1},
-		subnetMask: net.IP{255, 255, 255, 240},
+		name: "outside_range_start",
 		wantErrMsg: "dhcpv4: range start 192.168.10.20 is outside network " +
 			"192.168.10.1/28",
-	}, {
-		name:       "outside_range_end",
 		gatewayIP:  net.IP{192, 168, 10, 1},
-		subnetMask: net.IP{255, 255, 255, 224},
+		subnetMask: net.IP{255, 255, 255, 240},
+	}, {
+		name: "outside_range_end",
 		wantErrMsg: "dhcpv4: range end 192.168.10.200 is outside network " +
 			"192.168.10.1/27",
+		gatewayIP:  net.IP{192, 168, 10, 1},
+		subnetMask: net.IP{255, 255, 255, 224},
 	}}
 
 	for _, tc := range testCases {

internal/dhcpd/http.go

@@ -575,12 +575,15 @@ func (s *Server) handleReset(w http.ResponseWriter, r *http.Request) {
 		log.Error("dhcp: removing db: %s", err)
 	}
 
-	oldconf := s.conf
-	s.conf = ServerConfig{
-		WorkDir:        oldconf.WorkDir,
-		HTTPRegister:   oldconf.HTTPRegister,
-		ConfigModified: oldconf.ConfigModified,
-		DBFilePath:     oldconf.DBFilePath,
+	s.conf = &ServerConfig{
+		ConfigModified: s.conf.ConfigModified,
+
+		HTTPRegister: s.conf.HTTPRegister,
+
+		LocalDomainName: s.conf.LocalDomainName,
+
+		WorkDir:    s.conf.WorkDir,
+		DBFilePath: s.conf.DBFilePath,
 	}
 
 	v4conf := V4ServerConf{

internal/dhcpd/nullbool_test.go

@@ -12,33 +12,33 @@ import (
 func TestNullBool_UnmarshalJSON(t *testing.T) {
 	testCases := []struct {
 		name       string
-		data       []byte
 		wantErrMsg string
+		data       []byte
 		want       nullBool
 	}{{
 		name:       "empty",
-		data:       []byte{},
 		wantErrMsg: "",
+		data:       []byte{},
 		want:       nbNull,
 	}, {
 		name:       "null",
-		data:       []byte("null"),
 		wantErrMsg: "",
+		data:       []byte("null"),
 		want:       nbNull,
 	}, {
 		name:       "true",
-		data:       []byte("true"),
 		wantErrMsg: "",
+		data:       []byte("true"),
 		want:       nbTrue,
 	}, {
 		name:       "false",
-		data:       []byte("false"),
 		wantErrMsg: "",
+		data:       []byte("false"),
 		want:       nbFalse,
 	}, {
 		name:       "invalid",
-		data:       []byte("flase"),
-		wantErrMsg: `invalid nullBool value "flase"`,
+		wantErrMsg: `invalid nullBool value "invalid"`,
+		data:       []byte("invalid"),
 		want:       nbNull,
 	}}
 

internal/dhcpd/v4.go

@@ -969,11 +969,10 @@ func (s *v4Server) send(peer net.Addr, conn net.PacketConn, req, resp *dhcpv4.DH
 			Port: dhcpv4.ServerPort,
 		}
 		if mtype == dhcpv4.MessageTypeNak {
-			// Set the broadcast bit in the DHCPNAK, so that the
-			// relay agent broadcasted it to the client, because the
-			// client may not have a correct network address or
-			// subnet mask, and the client may not be answering ARP
-			// requests.
+			// Set the broadcast bit in the DHCPNAK, so that the relay agent
+			// broadcasts it to the client, because the client may not have
+			// a correct network address or subnet mask, and the client may not
+			// be answering ARP requests.
 			resp.SetBroadcast()
 		}
 	case mtype == dhcpv4.MessageTypeNak: