Added supplementary error checking (#99)

* Added supplementary errorichecking

* After running util.go through gofmt

* Updated main and util

* Minor updates to main and util

* Slight refactoring

* Add tests

main.go

@@ -16,13 +16,20 @@ import (
 
 func main() {
 	// Read global config
-	if fileExists("/etc/acme-dns/config.cfg") {
-		Config = readConfig("/etc/acme-dns/config.cfg")
+	var err error
+	if fileIsAccessible("/etc/acme-dns/config.cfg") {
 		log.WithFields(log.Fields{"file": "/etc/acme-dns/config.cfg"}).Info("Using config file")
-
-	} else {
+		Config, err = readConfig("/etc/acme-dns/config.cfg")
+	} else if fileIsAccessible("./config.cfg") {
 		log.WithFields(log.Fields{"file": "./config.cfg"}).Info("Using config file")
-		Config = readConfig("config.cfg")
+		Config, err = readConfig("./config.cfg")
+	} else {
+		log.Errorf("Configuration file not found.")
+		os.Exit(1)
+	}
+	if err != nil {
+		log.Errorf("Encountered an error while trying to read configuration file:  %s", err)
+		os.Exit(1)
 	}
 
 	setupLogging(Config.Logconfig.Format, Config.Logconfig.Level)
@@ -32,7 +39,7 @@ func main() {
 
 	// Open database
 	newDB := new(acmedb)
-	err := newDB.Init(Config.Database.Engine, Config.Database.Connection)
+	err = newDB.Init(Config.Database.Engine, Config.Database.Connection)
 	if err != nil {
 		log.Errorf("Could not open database [%v]", err)
 		os.Exit(1)

util.go

@@ -17,19 +17,23 @@ func jsonError(message string) []byte {
 	return []byte(fmt.Sprintf("{\"error\": \"%s\"}", message))
 }
 
-func fileExists(fname string) bool {
+func fileIsAccessible(fname string) bool {
 	_, err := os.Stat(fname)
 	if err != nil {
 		return false
 	}
+	f, err := os.Open(fname)
+	if err != nil {
+		return false
+	}
+	f.Close()
 	return true
 }
 
-func readConfig(fname string) DNSConfig {
+func readConfig(fname string) (DNSConfig, error) {
 	var conf DNSConfig
-	// Practically never errors
-	_, _ = toml.DecodeFile(fname, &conf)
-	return conf
+	_, err := toml.DecodeFile(fname, &conf)
+	return conf, err
 }
 
 func sanitizeString(s string) string {

util_test.go

@@ -1,10 +1,12 @@
 package main
 
 import (
-	log "github.com/sirupsen/logrus"
 	"io/ioutil"
 	"os"
+	"syscall"
 	"testing"
+
+	log "github.com/sirupsen/logrus"
 )
 
 func TestSetupLogging(t *testing.T) {
@@ -62,7 +64,7 @@ func TestReadConfig(t *testing.T) {
 		if err := tmpfile.Close(); err != nil {
 			t.Error("Could not close temporary file")
 		}
-		ret := readConfig(tmpfile.Name())
+		ret, _ := readConfig(tmpfile.Name())
 		if ret.General.Listen != test.output.General.Listen {
 			t.Errorf("Test %d: Expected listen value %s, but got %s", i, test.output.General.Listen, ret.General.Listen)
 		}
@@ -95,3 +97,33 @@ func TestGetIPListFromHeader(t *testing.T) {
 		}
 	}
 }
+
+func TestFileCheckPermissionDenied(t *testing.T) {
+	tmpfile, err := ioutil.TempFile("", "acmedns")
+	if err != nil {
+		t.Error("Could not create temporary file")
+	}
+	defer os.Remove(tmpfile.Name())
+	syscall.Chmod(tmpfile.Name(), 0000)
+	if fileIsAccessible(tmpfile.Name()) {
+		t.Errorf("File should not be accessible")
+	}
+	syscall.Chmod(tmpfile.Name(), 0644)
+}
+
+func TestFileCheckNotExists(t *testing.T) {
+	if fileIsAccessible("/path/that/does/not/exist") {
+		t.Errorf("File should not be accessible")
+	}
+}
+
+func TestFileCheckOK(t *testing.T) {
+	tmpfile, err := ioutil.TempFile("", "acmedns")
+	if err != nil {
+		t.Error("Could not create temporary file")
+	}
+	defer os.Remove(tmpfile.Name())
+	if !fileIsAccessible(tmpfile.Name()) {
+		t.Errorf("File should be accessible")
+	}
+}