Split code into modules

This is a massive commit that restructures the code into modules:

db/
    All functions related to modifying the Database

types/
    All type definitions and methods that can be exclusivly used on
    these types without dependencies

policy/
    All Policy related code, now without dependencies on the Database.

policy/matcher/
    Dedicated code to match machines in a list of FilterRules

Signed-off-by: Kristoffer Dalby <kristoffer@tailscale.com>

hscontrol/util/addr_test.go

@@ -0,0 +1,119 @@
+package util
+
+import (
+	"net/netip"
+	"reflect"
+	"testing"
+
+	"go4.org/netipx"
+)
+
+func Test_parseIPSet(t *testing.T) {
+	set := func(ips []string, prefixes []string) *netipx.IPSet {
+		var builder netipx.IPSetBuilder
+
+		for _, ip := range ips {
+			builder.Add(netip.MustParseAddr(ip))
+		}
+
+		for _, pre := range prefixes {
+			builder.AddPrefix(netip.MustParsePrefix(pre))
+		}
+
+		s, _ := builder.IPSet()
+
+		return s
+	}
+
+	type args struct {
+		arg  string
+		bits *int
+	}
+	tests := []struct {
+		name    string
+		args    args
+		want    *netipx.IPSet
+		wantErr bool
+	}{
+		{
+			name: "simple ip4",
+			args: args{
+				arg:  "10.0.0.1",
+				bits: nil,
+			},
+			want: set([]string{
+				"10.0.0.1",
+			}, []string{}),
+			wantErr: false,
+		},
+		{
+			name: "simple ip6",
+			args: args{
+				arg:  "2001:db8:abcd:1234::2",
+				bits: nil,
+			},
+			want: set([]string{
+				"2001:db8:abcd:1234::2",
+			}, []string{}),
+			wantErr: false,
+		},
+		{
+			name: "wildcard",
+			args: args{
+				arg:  "*",
+				bits: nil,
+			},
+			want: set([]string{}, []string{
+				"0.0.0.0/0",
+				"::/0",
+			}),
+			wantErr: false,
+		},
+		{
+			name: "prefix4",
+			args: args{
+				arg:  "192.168.0.0/16",
+				bits: nil,
+			},
+			want: set([]string{}, []string{
+				"192.168.0.0/16",
+			}),
+			wantErr: false,
+		},
+		{
+			name: "prefix6",
+			args: args{
+				arg:  "2001:db8:abcd:1234::/64",
+				bits: nil,
+			},
+			want: set([]string{}, []string{
+				"2001:db8:abcd:1234::/64",
+			}),
+			wantErr: false,
+		},
+		{
+			name: "range4",
+			args: args{
+				arg:  "192.168.0.0-192.168.255.255",
+				bits: nil,
+			},
+			want: set([]string{}, []string{
+				"192.168.0.0/16",
+			}),
+			wantErr: false,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, err := ParseIPSet(tt.args.arg, tt.args.bits)
+			if (err != nil) != tt.wantErr {
+				t.Errorf("parseIPSet() error = %v, wantErr %v", err, tt.wantErr)
+
+				return
+			}
+			if !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("parseIPSet() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}