Pull request 2100: v0.107.42-rc

Squashed commit of the following:

commit 284190f748345c7556e60b67f051ec5f6f080948
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Wed Dec 6 19:36:00 2023 +0300

    all: sync with master; upd chlog

internal/dhcpsvc/server.go

@@ -0,0 +1,100 @@
+package dhcpsvc
+
+import (
+	"fmt"
+	"sync/atomic"
+	"time"
+
+	"golang.org/x/exp/maps"
+	"golang.org/x/exp/slices"
+)
+
+// DHCPServer is a DHCP server for both IPv4 and IPv6 address families.
+type DHCPServer struct {
+	// enabled indicates whether the DHCP server is enabled and can provide
+	// information about its clients.
+	enabled *atomic.Bool
+
+	// localTLD is the top-level domain name to use for resolving DHCP
+	// clients' hostnames.
+	localTLD string
+
+	// interfaces4 is the set of IPv4 interfaces sorted by interface name.
+	interfaces4 []*iface4
+
+	// interfaces6 is the set of IPv6 interfaces sorted by interface name.
+	interfaces6 []*iface6
+
+	// leases is the set of active DHCP leases.
+	leases []*Lease
+
+	// icmpTimeout is the timeout for checking another DHCP server's presence.
+	icmpTimeout time.Duration
+}
+
+// New creates a new DHCP server with the given configuration.  It returns an
+// error if the given configuration can't be used.
+//
+// TODO(e.burkov):  Use.
+func New(conf *Config) (srv *DHCPServer, err error) {
+	if !conf.Enabled {
+		// TODO(e.burkov):  Perhaps return [Empty]?
+		return nil, nil
+	}
+
+	ifaces4 := make([]*iface4, len(conf.Interfaces))
+	ifaces6 := make([]*iface6, len(conf.Interfaces))
+
+	ifaceNames := maps.Keys(conf.Interfaces)
+	slices.Sort(ifaceNames)
+
+	var i4 *iface4
+	var i6 *iface6
+
+	for _, ifaceName := range ifaceNames {
+		iface := conf.Interfaces[ifaceName]
+
+		i4, err = newIface4(ifaceName, iface.IPv4)
+		if err != nil {
+			return nil, fmt.Errorf("interface %q: ipv4: %w", ifaceName, err)
+		} else if i4 != nil {
+			ifaces4 = append(ifaces4, i4)
+		}
+
+		i6 = newIface6(ifaceName, iface.IPv6)
+		if i6 != nil {
+			ifaces6 = append(ifaces6, i6)
+		}
+	}
+
+	enabled := &atomic.Bool{}
+	enabled.Store(conf.Enabled)
+
+	return &DHCPServer{
+		enabled:     enabled,
+		interfaces4: ifaces4,
+		interfaces6: ifaces6,
+		localTLD:    conf.LocalDomainName,
+		icmpTimeout: conf.ICMPTimeout,
+	}, nil
+}
+
+// type check
+//
+// TODO(e.burkov):  Uncomment when the [Interface] interface is implemented.
+// var _ Interface = (*DHCPServer)(nil)
+
+// Enabled implements the [Interface] interface for *DHCPServer.
+func (srv *DHCPServer) Enabled() (ok bool) {
+	return srv.enabled.Load()
+}
+
+// Leases implements the [Interface] interface for *DHCPServer.
+func (srv *DHCPServer) Leases() (leases []*Lease) {
+	leases = make([]*Lease, 0, len(srv.leases))
+	for _, lease := range srv.leases {
+		leases = append(leases, lease.Clone())
+	}
+
+	return leases
+}