cmd/resolver: implement command to update block.d hosts by its name

The following command: "resolver block.d update x" will fetch the
latest hosts file from the block.d provider "x" based on its registered
URL.

2 files changed, 53 insertions, 2 deletions

diff --git a/cmd/resolver/main.go b/cmd/resolver/main.go
index f2d4baf..a3ecbe5 100644
--- a/cmd/resolver/main.go
+++ b/cmd/resolver/main.go
@@ -15,6 +15,7 @@ import (
 
 // List of valid commands.
 const (
+	cmdBlockd = "block.d"
 	cmdCaches = "caches"
 	cmdEnv    = "env"
 	cmdQuery  = "query"
@@ -58,6 +59,26 @@ func main() {
 	rsol.cmd = strings.ToLower(args[0])
 
 	switch rsol.cmd {
+	case cmdBlockd:
+		args = args[1:]
+		if len(args) == 0 {
+			log.Fatalf("resolver: %s: missing sub command", cmdBlockd)
+		}
+
+		subCmd = strings.ToLower(args[0])
+
+		switch subCmd {
+		case subCmdUpdate:
+			args = args[1:]
+			if len(args) == 0 {
+				log.Fatalf("resolver: %s %s: missing argument", rsol.cmd, subCmd)
+			}
+			err = rsol.blockdUpdate(args[0])
+			if err != nil {
+				log.Fatalf("resolver: %s %s: %s", rsol.cmd, subCmd, err)
+			}
+		}
+
 	case cmdCaches:
 		args = args[1:]
 		if len(args) == 0 {
@@ -178,6 +199,13 @@ query <domain / ip-address> [type] [class]
 	Valid class are either IN, CS, HS.
 	Default value is IN.
 
+block.d update <name>
+
+	Fetch the latest hosts file from remote block.d URL defined by
+	its name.
+	On success, the hosts file will be updated and the server will be
+	restarted.
+
 caches
 
 	Fetch and print all caches from rescached server.
diff --git a/cmd/resolver/resolver.go b/cmd/resolver/resolver.go
index 697953d..76c5a13 100644
--- a/cmd/resolver/resolver.go
+++ b/cmd/resolver/resolver.go
@@ -45,6 +45,31 @@ type resolver struct {
 	insecure bool
 }
 
+// blockdUpdate fetch the latest hosts file from remote block.d URL defined by
+// its name.
+func (rsol *resolver) blockdUpdate(blockdName string) (err error) {
+	var (
+		resc = rsol.newRescachedClient()
+
+		hb     interface{}
+		hbjson []byte
+	)
+
+	hb, err = resc.BlockdUpdate(blockdName)
+	if err != nil {
+		return err
+	}
+
+	hbjson, err = json.MarshalIndent(hb, "", "  ")
+	if err != nil {
+		return err
+	}
+
+	fmt.Println(string(hbjson))
+
+	return nil
+}
+
 // doCmdCaches call the rescached HTTP API to fetch all caches.
 func (rsol *resolver) doCmdCaches() {
 	var (
@@ -252,10 +277,8 @@ func (rsol *resolver) doCmdQuery(args []string) {
 	}
 }
 
-//
 // initSystemResolver read the system resolv.conf to create fallback DNS
 // resolver.
-//
 func (rsol *resolver) initSystemResolver() (err error) {
 	var (
 		logp = "initSystemResolver"