all: refactoring Server initialization

Previously, we initialize the rescached Server by passing the
path to configuration file and initialize the environment inside the
server.

This commit changes it to pass the instance of Environment.  The idea
is to allow creating and running rescached Server without creating
configuration file first.

1 files changed, 29 insertions, 21 deletions

diff --git a/environment.go b/environment.go
index fdf4bd4..21cefd9 100644
--- a/environment.go
+++ b/environment.go
@@ -6,7 +6,6 @@ package rescached
 
 import (
 	"fmt"
-	"log"
 	"strconv"
 	"strings"
 
@@ -51,12 +50,14 @@ const (
 )
 
 //
-// environment for running rescached.
+// Environment for running rescached.
 //
-type environment struct {
+type Environment struct {
 	dns.ServerOptions
-	WUIListen      string   `ini:"rescached::wui.listen"`
-	FileResolvConf string   `ini:"rescached::file.resolvconf"`
+	WUIListen      string `ini:"rescached::wui.listen"`
+	FileResolvConf string `ini:"rescached::file.resolvconf"`
+	fileConfig     string
+
 	Debug          int      `ini:"rescached::debug"`
 	HostsBlocksRaw []string `ini:"rescached::hosts_block" json:"-"`
 	HostsBlocks    []*hostsBlock
@@ -64,48 +65,55 @@ type environment struct {
 	Zones          map[string]*dns.Zone
 }
 
-func loadEnvironment(file string) (env *environment) {
-	env = newEnvironment()
+//
+// LoadEnvironment initialize environment from configuration file.
+//
+func LoadEnvironment(fileConfig string) (env *Environment, err error) {
+	var (
+		logp = "LoadEnvironment"
+		cfg  *ini.Ini
+	)
+
+	env = newEnvironment(fileConfig)
 
-	if len(file) == 0 {
+	if len(fileConfig) == 0 {
 		env.init()
-		return env
+		return env, nil
 	}
 
-	cfg, err := ini.Open(file)
+	cfg, err = ini.Open(fileConfig)
 	if err != nil {
-		log.Printf("loadEnvironment %q: %s", file, err)
-		return env
+		return nil, fmt.Errorf("%s: %q: %s", logp, fileConfig, err)
 	}
 
 	err = cfg.Unmarshal(env)
 	if err != nil {
-		log.Printf("loadEnvironment %q: %s", file, err)
-		return env
+		return nil, fmt.Errorf("%s: %q: %s", logp, fileConfig, err)
 	}
 
 	env.init()
 	env.initHostsBlock(cfg)
 	debug.Value = env.Debug
 
-	return env
+	return env, nil
 }
 
 //
 // newEnvironment create and initialize options with default values.
 //
-func newEnvironment() *environment {
-	return &environment{
+func newEnvironment(fileConfig string) *Environment {
+	return &Environment{
 		ServerOptions: dns.ServerOptions{
 			ListenAddress: "127.0.0.1:53",
 		},
+		fileConfig: fileConfig,
 	}
 }
 
 //
 // init check and initialize the environment instance with default values.
 //
-func (env *environment) init() {
+func (env *Environment) init() {
 	if len(env.WUIListen) == 0 {
 		env.WUIListen = defWuiAddress
 	}
@@ -117,7 +125,7 @@ func (env *environment) init() {
 	}
 }
 
-func (env *environment) initHostsBlock(cfg *ini.Ini) {
+func (env *Environment) initHostsBlock(cfg *ini.Ini) {
 	env.HostsBlocks = hostsBlockSources
 
 	for x, v := range env.HostsBlocksRaw {
@@ -129,7 +137,7 @@ func (env *environment) initHostsBlock(cfg *ini.Ini) {
 	}
 }
 
-func (env *environment) loadResolvConf() (ok bool, err error) {
+func (env *Environment) loadResolvConf() (ok bool, err error) {
 	rc, err := libnet.NewResolvConf(env.FileResolvConf)
 	if err != nil {
 		return false, err
@@ -161,7 +169,7 @@ func (env *environment) loadResolvConf() (ok bool, err error) {
 //
 // write the options values back to file.
 //
-func (env *environment) write(file string) (err error) {
+func (env *Environment) write(file string) (err error) {
 	in, err := ini.Open(file)
 	if err != nil {
 		return fmt.Errorf("write: %w", err)