Pull request: * all: move internal Go packages to internal/

Merge in DNS/adguard-home from 2234-move-to-internal to master

Squashed commit of the following:

commit d26a288cabeac86f9483fab307677b1027c78524
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Fri Oct 30 12:44:18 2020 +0300

    * all: move internal Go packages to internal/

    Closes #2234.

internal/dhcpd/dhcpd.go

@@ -0,0 +1,259 @@
+package dhcpd
+
+import (
+	"encoding/hex"
+	"net"
+	"net/http"
+	"path/filepath"
+	"strconv"
+	"strings"
+	"time"
+
+	"github.com/AdguardTeam/AdGuardHome/internal/util"
+	"github.com/AdguardTeam/golibs/log"
+)
+
+const defaultDiscoverTime = time.Second * 3
+const leaseExpireStatic = 1
+
+var webHandlersRegistered = false
+
+// Lease contains the necessary information about a DHCP lease
+type Lease struct {
+	HWAddr   net.HardwareAddr `json:"mac"`
+	IP       net.IP           `json:"ip"`
+	Hostname string           `json:"hostname"`
+
+	// Lease expiration time
+	// 1: static lease
+	Expiry time.Time `json:"expires"`
+}
+
+// ServerConfig - DHCP server configuration
+// field ordering is important -- yaml fields will mirror ordering from here
+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:"-"`
+}
+
+type OnLeaseChangedT func(flags int)
+
+// flags for onLeaseChanged()
+const (
+	LeaseChangedAdded = iota
+	LeaseChangedAddedStatic
+	LeaseChangedRemovedStatic
+
+	LeaseChangedDBStore
+)
+
+// Server - the current state of the DHCP server
+type Server struct {
+	srv4 DHCPServer
+	srv6 DHCPServer
+
+	conf ServerConfig
+
+	// Called when the leases DB is modified
+	onLeaseChanged []OnLeaseChangedT
+}
+
+type ServerInterface interface {
+	Leases(flags int) []Lease
+	SetOnLeaseChanged(onLeaseChanged OnLeaseChangedT)
+}
+
+// CheckConfig checks the configuration
+func (s *Server) CheckConfig(config ServerConfig) error {
+	return nil
+}
+
+// Create - create object
+func Create(config ServerConfig) *Server {
+	s := Server{}
+	s.conf.Enabled = config.Enabled
+	s.conf.InterfaceName = config.InterfaceName
+	s.conf.HTTPRegister = config.HTTPRegister
+	s.conf.ConfigModified = config.ConfigModified
+	s.conf.DBFilePath = filepath.Join(config.WorkDir, dbFilename)
+
+	if !webHandlersRegistered && s.conf.HTTPRegister != nil {
+		webHandlersRegistered = true
+		s.registerHandlers()
+	}
+
+	var err4, err6 error
+	v4conf := config.Conf4
+	v4conf.Enabled = s.conf.Enabled
+	if len(v4conf.RangeStart) == 0 {
+		v4conf.Enabled = false
+	}
+	v4conf.InterfaceName = s.conf.InterfaceName
+	v4conf.notify = s.onNotify
+	s.srv4, err4 = v4Create(v4conf)
+
+	v6conf := config.Conf6
+	v6conf.Enabled = s.conf.Enabled
+	if len(v6conf.RangeStart) == 0 {
+		v6conf.Enabled = false
+	}
+	v6conf.InterfaceName = s.conf.InterfaceName
+	v6conf.notify = s.onNotify
+	s.srv6, err6 = v6Create(v6conf)
+
+	if err4 != nil {
+		log.Error("%s", err4)
+		return nil
+	}
+	if err6 != nil {
+		log.Error("%s", err6)
+		return nil
+	}
+
+	if s.conf.Enabled && !v4conf.Enabled && !v6conf.Enabled {
+		log.Error("Can't enable DHCP server because neither DHCPv4 nor DHCPv6 servers are configured")
+		return nil
+	}
+
+	// we can't delay database loading until DHCP server is started,
+	//  because we need static leases functionality available beforehand
+	s.dbLoad()
+	return &s
+}
+
+// server calls this function after DB is updated
+func (s *Server) onNotify(flags uint32) {
+	if flags == LeaseChangedDBStore {
+		s.dbStore()
+		return
+	}
+
+	s.notify(int(flags))
+}
+
+// SetOnLeaseChanged - set callback
+func (s *Server) SetOnLeaseChanged(onLeaseChanged OnLeaseChangedT) {
+	s.onLeaseChanged = append(s.onLeaseChanged, onLeaseChanged)
+}
+
+func (s *Server) notify(flags int) {
+	if len(s.onLeaseChanged) == 0 {
+		return
+	}
+	for _, f := range s.onLeaseChanged {
+		f(flags)
+	}
+}
+
+// WriteDiskConfig - write configuration
+func (s *Server) WriteDiskConfig(c *ServerConfig) {
+	c.Enabled = s.conf.Enabled
+	c.InterfaceName = s.conf.InterfaceName
+	s.srv4.WriteDiskConfig4(&c.Conf4)
+	s.srv6.WriteDiskConfig6(&c.Conf6)
+}
+
+// Start will listen on port 67 and serve DHCP requests.
+func (s *Server) Start() error {
+	err := s.srv4.Start()
+	if err != nil {
+		log.Error("DHCPv4: start: %s", err)
+		return err
+	}
+
+	err = s.srv6.Start()
+	if err != nil {
+		log.Error("DHCPv6: start: %s", err)
+		return err
+	}
+
+	return nil
+}
+
+// Stop closes the listening UDP socket
+func (s *Server) Stop() {
+	s.srv4.Stop()
+	s.srv6.Stop()
+}
+
+// flags for Leases() function
+const (
+	LeasesDynamic = 1
+	LeasesStatic  = 2
+	LeasesAll     = LeasesDynamic | LeasesStatic
+)
+
+// Leases returns the list of current DHCP leases (thread-safe)
+func (s *Server) Leases(flags int) []Lease {
+	result := s.srv4.GetLeases(flags)
+
+	v6leases := s.srv6.GetLeases(flags)
+	result = append(result, v6leases...)
+
+	return result
+}
+
+// FindMACbyIP - find a MAC address by IP address in the currently active DHCP leases
+func (s *Server) FindMACbyIP(ip net.IP) net.HardwareAddr {
+	if ip.To4() != nil {
+		return s.srv4.FindMACbyIP(ip)
+	}
+	return s.srv6.FindMACbyIP(ip)
+}
+
+// AddStaticLease - add static v4 lease
+func (s *Server) AddStaticLease(lease Lease) error {
+	return s.srv4.AddStaticLease(lease)
+}
+
+// Parse option string
+// Format:
+// CODE TYPE VALUE
+func parseOptionString(s string) (uint8, []byte) {
+	s = strings.TrimSpace(s)
+	scode := util.SplitNext(&s, ' ')
+	t := util.SplitNext(&s, ' ')
+	sval := util.SplitNext(&s, ' ')
+
+	code, err := strconv.Atoi(scode)
+	if err != nil || code <= 0 || code > 255 {
+		return 0, nil
+	}
+
+	var val []byte
+
+	switch t {
+	case "hex":
+		val, err = hex.DecodeString(sval)
+		if err != nil {
+			return 0, nil
+		}
+
+	case "ip":
+		ip := net.ParseIP(sval)
+		if ip == nil {
+			return 0, nil
+		}
+		val = ip
+		if ip.To4() != nil {
+			val = ip.To4()
+		}
+
+	default:
+		return 0, nil
+	}
+
+	return uint8(code), val
+}