Pull request 2070: 4923 gopacket DHCP vol.4

Merge in DNS/adguard-home from 4923-gopacket-dhcp-vol.4 to master

Updates #4923.

Squashed commit of the following:

commit 4b87258c70ac98b2abb1ac95f7e916e244b3cd08
Merge: 61458864f 9b91a8740
Author: Eugene Burkov <E.Burkov@AdGuard.COM>
Date:   Thu Nov 16 14:05:34 2023 +0300

    Merge branch 'master' into 4923-gopacket-dhcp-vol.4

commit 61458864f3df7a027e65060a5f0fb516cc7911a7
Author: Eugene Burkov <E.Burkov@AdGuard.COM>
Date:   Wed Nov 15 18:48:40 2023 +0300

    all: imp code

commit 506a0ab81e76beebb900f86580577563b471e4e2
Author: Eugene Burkov <E.Burkov@AdGuard.COM>
Date:   Tue Nov 14 15:59:56 2023 +0300

    all: cleanup moving lease

commit 8d218b732662ac4308ed09d28c1bf9f65906d47c
Author: Eugene Burkov <E.Burkov@AdGuard.COM>
Date:   Mon Nov 13 18:13:39 2023 +0300

    all: rm old leases type

internal/dhcpsvc/server.go

@@ -25,6 +25,9 @@ type DHCPServer struct {
 	// 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
 }
@@ -75,3 +78,23 @@ func New(conf *Config) (srv *DHCPServer, err error) {
 		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
+}