config.go: iterate slices via indices to get pointers instead of copies

Iterating over a slice returns a copy of the respective member instead
of a reference to the original slice member. Thus, any modification are
discarded and the pointers saved inside cfg.users and cfg.rrconfigs are
incorrect, too.

config.go

@@ -61,7 +61,8 @@ func prepareConfig(cfg *Config) (*Config, error) {
 
 	// populate user map
 	cfg.users = map[string]*User{}
-	for _, user := range cfg.Users {
+	for u := range cfg.Users {
+		user := &cfg.Users[u]
 		if _, ok := cfg.users[user.Username]; ok {
 			return nil, fmt.Errorf("Duplicate username detected: %s", user.Username)
 		}
@@ -80,12 +81,14 @@ func prepareConfig(cfg *Config) (*Config, error) {
 			user.records[record] = true
 			globRecords[record] = true
 		}
-		cfg.users[user.Username] = &user
+		cfg.users[user.Username] = user
 	}
 
 	// populate record map
 	cfg.rrconfigs = map[string]*RRConfig{}
-	for _, record := range cfg.RRConfigs {
+	for r := range cfg.RRConfigs {
+		record := &cfg.RRConfigs[r]
+
 		// check for duplicate record before verifying association to users
 		if _, ok := cfg.rrconfigs[record.Recordname]; ok {
 			return nil, fmt.Errorf("Duplicate record detected: %s", record.Recordname)
@@ -97,7 +100,7 @@ func prepareConfig(cfg *Config) (*Config, error) {
 		// need to remove record from globRecords for detecting orphaned records
 		delete(globRecords, record.Recordname)
 
-		cfg.rrconfigs[record.Recordname] = &record
+		cfg.rrconfigs[record.Recordname] = record
 	}
 
 	// check whether all records have been processed