ipn/ipnlocal: use views for Peer.PrimaryRoutes and Peer.Tags

RELNOTE=`tailscale status --json` now shows Tags and PrimaryRoutes

Signed-off-by: Maisem Ali <maisem@tailscale.com>

types/views/views.go

@@ -7,6 +7,9 @@
 package views
 
 import (
+	"encoding/json"
+	"errors"
+
 	"inet.af/netaddr"
 	"tailscale.com/net/tsaddr"
 )
@@ -21,6 +24,28 @@ type StringSlice struct {
 // StringSliceOf returns a StringSlice for the provided slice.
 func StringSliceOf(x []string) StringSlice { return StringSlice{x} }
 
+// MarshalJSON implements json.Marshaler.
+func (v StringSlice) MarshalJSON() ([]byte, error) {
+	return json.Marshal(v.ж)
+}
+
+// UnmarshalJSON implements json.Unmarshaler.
+func (v *StringSlice) UnmarshalJSON(b []byte) error {
+	if v.ж != nil {
+		return errors.New("StringSlice is already initialized")
+	}
+	if len(b) == 0 {
+		return nil
+	}
+	if err := json.Unmarshal(b, &v.ж); err != nil {
+		return err
+	}
+	return nil
+}
+
+// IsNil reports whether the underlying slice is nil.
+func (v StringSlice) IsNil() bool { return v.ж == nil }
+
 // Len returns the length of the slice.
 func (v StringSlice) Len() int { return len(v.ж) }
 
@@ -47,6 +72,9 @@ type IPPrefixSlice struct {
 // IPPrefixSliceOf returns a IPPrefixSlice for the provided slice.
 func IPPrefixSliceOf(x []netaddr.IPPrefix) IPPrefixSlice { return IPPrefixSlice{x} }
 
+// IsNil reports whether the underlying slice is nil.
+func (v IPPrefixSlice) IsNil() bool { return v.ж == nil }
+
 // Len returns the length of the slice.
 func (v IPPrefixSlice) Len() int { return len(v.ж) }
 
@@ -72,3 +100,22 @@ func (v IPPrefixSlice) ContainsIP(ip netaddr.IP) bool {
 func (v IPPrefixSlice) ContainsFunc(f func(netaddr.IPPrefix) bool) bool {
 	return tsaddr.PrefixesContainsFunc(v.ж, f)
 }
+
+// MarshalJSON implements json.Marshaler.
+func (v IPPrefixSlice) MarshalJSON() ([]byte, error) {
+	return json.Marshal(v.ж)
+}
+
+// UnmarshalJSON implements json.Unmarshaler.
+func (v *IPPrefixSlice) UnmarshalJSON(b []byte) error {
+	if v.ж != nil {
+		return errors.New("IPPrefixSlice is already initialized")
+	}
+	if len(b) == 0 {
+		return nil
+	}
+	if err := json.Unmarshal(b, &v.ж); err != nil {
+		return err
+	}
+	return nil
+}

types/views/views_test.go

@@ -0,0 +1,73 @@
+// Copyright (c) 2022 Tailscale Inc & AUTHORS All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package views
+
+import (
+	"bytes"
+	"encoding/json"
+	"reflect"
+	"strings"
+	"testing"
+
+	"inet.af/netaddr"
+)
+
+func TestViewsJSON(t *testing.T) {
+	mustCIDR := func(cidrs ...string) (out []netaddr.IPPrefix) {
+		for _, cidr := range cidrs {
+			out = append(out, netaddr.MustParseIPPrefix(cidr))
+		}
+		return
+	}
+	type viewStruct struct {
+		Addrs      IPPrefixSlice
+		Strings    StringSlice
+		AddrsPtr   *IPPrefixSlice `json:",omitempty"`
+		StringsPtr *StringSlice   `json:",omitempty"`
+	}
+	tests := []struct {
+		name     string
+		in       viewStruct
+		wantJSON string
+	}{
+		{
+			name:     "empty",
+			in:       viewStruct{},
+			wantJSON: `{"Addrs":null,"Strings":null}`,
+		},
+		{
+			name: "everything",
+			in: viewStruct{
+				Addrs:      IPPrefixSliceOf(mustCIDR("192.168.0.0/24")),
+				AddrsPtr:   &IPPrefixSlice{mustCIDR("192.168.0.0/24")},
+				StringsPtr: &StringSlice{[]string{"foo"}},
+				Strings:    StringSlice{[]string{"bar"}},
+			},
+			wantJSON: `{"Addrs":["192.168.0.0/24"],"Strings":["bar"],"AddrsPtr":["192.168.0.0/24"],"StringsPtr":["foo"]}`,
+		},
+	}
+
+	var buf bytes.Buffer
+	encoder := json.NewEncoder(&buf)
+	encoder.SetIndent("", "")
+	for _, tc := range tests {
+		buf.Reset()
+		if err := encoder.Encode(&tc.in); err != nil {
+			t.Fatal(err)
+		}
+		b := buf.Bytes()
+		gotJSON := strings.TrimSpace(string(b))
+		if tc.wantJSON != gotJSON {
+			t.Fatalf("JSON: %v; want: %v", gotJSON, tc.wantJSON)
+		}
+		var got viewStruct
+		if err := json.Unmarshal(b, &got); err != nil {
+			t.Fatal(err)
+		}
+		if !reflect.DeepEqual(got, tc.in) {
+			t.Fatalf("unmarshal resulted in different output: %+v; want %+v", got, tc.in)
+		}
+	}
+}