sort rules by name

Sort rules by name, so they're checked in alphabetical order.

This way, you can place deny rules at the top of the list to get better
performance, since it won't check the rest of the rules.

Discussion: #36

daemon/rule/loader.go

@@ -7,6 +7,7 @@ import (
 	"os"
 	"path"
 	"path/filepath"
+	"sort"
 	"strings"
 	"sync"
 	"time"
@@ -24,6 +25,7 @@ type Loader struct {
 	sync.RWMutex
 	path              string
 	rules             map[string]*Rule
+	rulesKeys         []string
 	watcher           *fsnotify.Watcher
 	liveReload        bool
 	liveReloadRunning bool
@@ -103,6 +105,8 @@ func (l *Loader) Load(path string) error {
 		}
 	}
 
+	l.sortRules()
+
 	if l.liveReload && l.liveReloadRunning == false {
 		go l.liveReloadWorker()
 	}
@@ -167,6 +171,14 @@ func (l *Loader) setUniqueName(rule *Rule) {
 	}
 }
 
+func (l *Loader) sortRules() {
+	l.rulesKeys = make([]string, 0, len(l.rules))
+	for k := range l.rules {
+		l.rulesKeys = append(l.rulesKeys, k)
+	}
+	sort.Strings(l.rulesKeys)
+}
+
 func (l *Loader) addUserRule(rule *Rule) {
 	if rule.Duration == Once {
 		return
@@ -184,6 +196,7 @@ func (l *Loader) replaceUserRule(rule *Rule) {
 		}
 	}
 	l.rules[rule.Name] = rule
+	l.sortRules()
 	l.Unlock()
 
 	if rule.Duration == Restart || rule.Duration == Always {
@@ -198,6 +211,7 @@ func (l *Loader) replaceUserRule(rule *Rule) {
 	time.AfterFunc(tTime, func() {
 		l.Lock()
 		delete(l.rules, rule.Name)
+		l.sortRules()
 		l.Unlock()
 	})
 }
@@ -248,10 +262,17 @@ func (l *Loader) Delete(ruleName string) error {
 	defer l.Unlock()
 
 	rule := l.rules[ruleName]
+	if rule == nil {
+		return nil
+	}
+
 	delete(l.rules, ruleName)
-	if rule == nil || rule.Duration != Always {
+	l.sortRules()
+
+	if rule.Duration != Always {
 		return nil
 	}
+
 	log.Info("Delete() rule: ", rule)
 	path := fmt.Sprint(l.path, "/", ruleName, ".json")
 	return os.Remove(path)
@@ -262,7 +283,11 @@ func (l *Loader) FindFirstMatch(con *conman.Connection) (match *Rule) {
 	l.RLock()
 	defer l.RUnlock()
 
-	for _, rule := range l.rules {
+	for _, ruleIdx := range l.rulesKeys {
+		rule, valid := l.rules[ruleIdx]
+		if !valid {
+			continue
+		}
 		// if we already have a match, we don't need
 		// to evaluate 'allow' rules anymore, we only
 		// need to make sure there's no 'deny' rule