all: apply suggestions from linter

List of changes,

* Remove unused constants keyIsEnabled, keyIsSystem, and keyLastUpdated.
* Use the method String on instance of Duration instead of fmt.Sprintf.
* Replace any usage of io/ioutil package with its replacement.
* Check for error from calling Environment.init and Zone.Add.
* Prefix all returned error on hostsBlock.update method.
* Add "lint" task as part of default target, build.

1 files changed, 21 insertions, 5 deletions

diff --git a/httpd.go b/httpd.go
index 7eacaa1..c698bf4 100644
--- a/httpd.go
+++ b/httpd.go
@@ -325,6 +325,7 @@ func (srv *Server) httpdAPIGetEnvironment(epr *libhttp.EndpointRequest) (resBody
 
 func (srv *Server) httpdAPIPostEnvironment(epr *libhttp.EndpointRequest) (resBody []byte, err error) {
 	var (
+		logp    = "httpdAPIPostEnvironment"
 		res     = libhttp.EndpointResponse{}
 		newOpts = new(Environment)
 	)
@@ -342,7 +343,12 @@ func (srv *Server) httpdAPIPostEnvironment(epr *libhttp.EndpointRequest) (resBod
 		return nil, &res
 	}
 
-	newOpts.init()
+	err = newOpts.init()
+	if err != nil {
+		res.Code = http.StatusInternalServerError
+		res.Message = fmt.Sprintf("%s: %s", logp, err)
+		return nil, &res
+	}
 
 	fmt.Printf("new options: %+v\n", newOpts)
 
@@ -474,17 +480,22 @@ func (srv *Server) hostsBlockEnable(hb *hostsBlock) (err error) {
 }
 
 func (srv *Server) hostsBlockDisable(hb *hostsBlock) (err error) {
-	var hfile *dns.HostsFile
+	var (
+		logp = "hostsBlockDisable"
+
+		hfile *dns.HostsFile
+	)
+
 	hfile = srv.env.HostsFiles[hb.Name]
 	if hfile == nil {
-		return fmt.Errorf("unknown hosts block: %q", hb.Name)
+		return fmt.Errorf("%s: unknown hosts block: %q", logp, hb.Name)
 	}
 
 	srv.dns.RemoveLocalCachesByNames(hfile.Names())
 
 	err = hb.hide()
 	if err != nil {
-		return err
+		return fmt.Errorf("%s: %w", logp, err)
 	}
 	delete(srv.env.HostsFiles, hb.Name)
 
@@ -872,7 +883,12 @@ func (srv *Server) apiZoneRRCreate(epr *libhttp.EndpointRequest) (resbody []byte
 	}
 
 	// Update the Zone file.
-	zoneFile.Add(rr)
+	err = zoneFile.Add(rr)
+	if err != nil {
+		res.Message = err.Error()
+		return nil, &res
+	}
+
 	err = zoneFile.Save()
 	if err != nil {
 		res.Message = err.Error()