ipn: implement Prefs.Equals efficiently.

Signed-off-by: David Anderson <dave@natulte.net>

ipn/prefs.go

@@ -36,32 +36,57 @@ type Prefs struct {
 }
 
 // IsEmpty reports whether p is nil or pointing to a Prefs zero value.
-func (uc *Prefs) IsEmpty() bool { return uc == nil || uc.Equals(&Prefs{}) }
+func (p *Prefs) IsEmpty() bool { return p == nil || p.Equals(&Prefs{}) }
 
-func (uc *Prefs) Pretty() string {
-	var ucp string
-	if uc.Persist != nil {
-		ucp = uc.Persist.Pretty()
+func (p *Prefs) Pretty() string {
+	var pp string
+	if p.Persist != nil {
+		pp = p.Persist.Pretty()
 	} else {
-		ucp = "Persist=nil"
+		pp = "Persist=nil"
 	}
 	return fmt.Sprintf("Prefs{ra=%v mesh=%v dns=%v want=%v notepad=%v pf=%v routes=%v %v}",
-		uc.RouteAll, uc.AllowSingleHosts, uc.CorpDNS, uc.WantRunning,
-		uc.NotepadURLs, uc.UsePacketFilter, uc.AdvertiseRoutes, ucp)
+		p.RouteAll, p.AllowSingleHosts, p.CorpDNS, p.WantRunning,
+		p.NotepadURLs, p.UsePacketFilter, p.AdvertiseRoutes, pp)
 }
 
-func (uc *Prefs) ToBytes() []byte {
-	data, err := json.MarshalIndent(uc, "", "\t")
+func (p *Prefs) ToBytes() []byte {
+	data, err := json.MarshalIndent(p, "", "\t")
 	if err != nil {
 		log.Fatalf("Prefs marshal: %v\n", err)
 	}
 	return data
 }
 
-func (uc *Prefs) Equals(uc2 *Prefs) bool {
-	b1 := uc.ToBytes()
-	b2 := uc2.ToBytes()
-	return bytes.Equal(b1, b2)
+func (p *Prefs) Equals(p2 *Prefs) bool {
+	if p == nil && p2 == nil {
+		return true
+	}
+	if p == nil || p2 == nil {
+		return false
+	}
+
+	return p != nil && p2 != nil &&
+		p.RouteAll == p2.RouteAll &&
+		p.AllowSingleHosts == p2.AllowSingleHosts &&
+		p.CorpDNS == p2.CorpDNS &&
+		p.WantRunning == p2.WantRunning &&
+		p.NotepadURLs == p2.NotepadURLs &&
+		p.UsePacketFilter == p2.UsePacketFilter &&
+		compareIPNets(p.AdvertiseRoutes, p2.AdvertiseRoutes) &&
+		p.Persist.Equals(p2.Persist)
+}
+
+func compareIPNets(a, b []*net.IPNet) bool {
+	if len(a) != len(b) {
+		return false
+	}
+	for i := range a {
+		if !a[i].IP.Equal(b[i].IP) || !bytes.Equal(a[i].Mask, b[i].Mask) {
+			return false
+		}
+	}
+	return true
 }
 
 func NewPrefs() Prefs {
@@ -78,45 +103,45 @@ func NewPrefs() Prefs {
 }
 
 func PrefsFromBytes(b []byte, enforceDefaults bool) (Prefs, error) {
-	uc := NewPrefs()
+	p := NewPrefs()
 	if len(b) == 0 {
-		return uc, nil
+		return p, nil
 	}
 	persist := &controlclient.Persist{}
 	err := json.Unmarshal(b, persist)
 	if err == nil && (persist.Provider != "" || persist.LoginName != "") {
 		// old-style relaynode config; import it
-		uc.Persist = persist
+		p.Persist = persist
 	} else {
-		err = json.Unmarshal(b, &uc)
+		err = json.Unmarshal(b, &p)
 		if err != nil {
 			log.Printf("Prefs parse: %v: %v\n", err, b)
 		}
 	}
 	if enforceDefaults {
-		uc.RouteAll = true
-		uc.AllowSingleHosts = true
+		p.RouteAll = true
+		p.AllowSingleHosts = true
 	}
-	return uc, err
+	return p, err
 }
 
-func (uc *Prefs) Copy() *Prefs {
-	uc2, err := PrefsFromBytes(uc.ToBytes(), false)
+func (p *Prefs) Copy() *Prefs {
+	p2, err := PrefsFromBytes(p.ToBytes(), false)
 	if err != nil {
 		log.Fatalf("Prefs was uncopyable: %v\n", err)
 	}
-	return &uc2
+	return &p2
 }
 
 func LoadPrefs(filename string, enforceDefaults bool) *Prefs {
 	log.Printf("Loading prefs %v\n", filename)
 	data, err := ioutil.ReadFile(filename)
-	uc := NewPrefs()
+	p := NewPrefs()
 	if err != nil {
 		log.Printf("Read: %v: %v\n", filename, err)
 		goto fail
 	}
-	uc, err = PrefsFromBytes(data, enforceDefaults)
+	p, err = PrefsFromBytes(data, enforceDefaults)
 	if err != nil {
 		log.Printf("Parse: %v: %v\n", filename, err)
 		goto fail
@@ -124,8 +149,8 @@ func LoadPrefs(filename string, enforceDefaults bool) *Prefs {
 	goto post
 fail:
 	log.Printf("failed to load config. Generating a new one.\n")
-	uc = NewPrefs()
-	uc.WantRunning = true
+	p = NewPrefs()
+	p.WantRunning = true
 post:
 	// Update: we changed our minds :)
 	// Versabank would like to persist the setting across reboots, for now,
@@ -138,15 +163,15 @@ post:
 		// know how, rebooting will fix it.
 		// We still persist WantRunning just in case we change our minds on
 		// this topic.
-		uc.WantRunning = true
+		p.WantRunning = true
 	}
-	log.Printf("Loaded prefs %v %v\n", filename, uc.Pretty())
-	return &uc
+	log.Printf("Loaded prefs %v %v\n", filename, p.Pretty())
+	return &p
 }
 
-func SavePrefs(filename string, uc *Prefs) {
-	log.Printf("Saving prefs %v %v\n", filename, uc.Pretty())
-	data := uc.ToBytes()
+func SavePrefs(filename string, p *Prefs) {
+	log.Printf("Saving prefs %v %v\n", filename, p.Pretty())
+	data := p.ToBytes()
 	os.MkdirAll(filepath.Dir(filename), 0700)
 	if err := atomicfile.WriteFile(filename, data, 0666); err != nil {
 		log.Printf("SavePrefs: %v\n", err)