Use internal DNS cache

Otherwise ANY call will call a DNS resolve.

README.md

@@ -21,6 +21,7 @@ All parameters can be passed via cmdline arguments or via environment variables.
 - ``-polling`` / ``POLLING`` Refresh interval in seconds. (optional, 300 seconds as default)
 - ``-tempchange`` / ``TEMPCHANGE`` Temperature change warning in hours. (optional, 12 hours as default)
 - ``-full`` / ``FULL`` Provide any information to broker, most times this is not necessary. (optional)
+- ``-dns`` / ``DNS`` Use internal DNS cache. (optional, default: true)
 - ``-verbose`` / ``VERBOSE`` Provide more verbose logging. (optional)
 
 

go.mod

@@ -1,6 +1,7 @@
 module github.com/misery/HeatingMqttBridge
 
 require github.com/eclipse/paho.mqtt.golang v1.4.2
+require github.com/ncruces/go-dns v1.2.0
 
 require (
 	github.com/gorilla/websocket v1.5.0 // indirect

go.sum

@@ -5,6 +5,8 @@ github.com/eclipse/paho.mqtt.golang v1.4.2/go.mod h1:JGt0RsEwEX+Xa/agj90YJ9d9DH2
 github.com/gorilla/websocket v1.4.2/go.mod h1:YR8l580nyteQvAITg2hZ9XVh4b55+EU/adAjf1fMHhE=
 github.com/gorilla/websocket v1.5.0 h1:PPwGk2jz7EePpoHN/+ClbZu8SPxiqlu12wZP/3sWmnc=
 github.com/gorilla/websocket v1.5.0/go.mod h1:YR8l580nyteQvAITg2hZ9XVh4b55+EU/adAjf1fMHhE=
+github.com/ncruces/go-dns v1.2.0 h1:eSiRR6vRBaXtTbvS8gy4/RFk5ahO3W5VCipA5iBTylc=
+github.com/ncruces/go-dns v1.2.0/go.mod h1:sZV4lxB+nXBYekemnR/EKewk8pZFTdFzF+LK2d7JPFg=
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
 golang.org/x/net v0.0.0-20200425230154-ff2c4b7c35a0/go.mod h1:qpuaurCH72eLCgpAm/N6yyVIVM9cpaDIP3A8BGJEC5A=
 golang.org/x/net v0.0.0-20220909164309-bea034e7d591 h1:D0B/7al0LLrVC8aWF4+oxpv/m8bc7ViFfVS8/gXGdqI=

main.go

@@ -32,6 +32,7 @@ import (
 	"fmt"
 	"io"
 	"log"
+	"net"
 	"net/http"
 	"net/url"
 	"os"
@@ -42,6 +43,7 @@ import (
 	"time"
 
 	MQTT "github.com/eclipse/paho.mqtt.golang"
+	DNS "github.com/ncruces/go-dns"
 )
 
 var bridge *bridgeCfg
@@ -636,6 +638,7 @@ func createBridge() *bridgeCfg {
 	polling := flag.Int("polling", 300, "Refresh interval in seconds")
 	tempchange := flag.Int("tempchange", 12, "Temperature change warning in hours")
 	full := flag.Bool("full", false, "Provide full information to broker")
+	dnsCache := flag.Bool("dns", true, "Use internal DNS cache")
 	verbose := flag.Bool("verbose", false, "Provide verbose log information")
 	flag.Parse()
 
@@ -648,6 +651,7 @@ func createBridge() *bridgeCfg {
 	if *env {
 		setBoolParam(clean, "clean")
 		setBoolParam(full, "full")
+		setBoolParam(dnsCache, "dns")
 		setBoolParam(verbose, "verbose")
 
 		if !isFlagPassed("polling") {
@@ -671,6 +675,11 @@ func createBridge() *bridgeCfg {
 		*tempchange = 12
 	}
 
+	if *dnsCache {
+		log.Println("Use internal DNS cache")
+		net.DefaultResolver = DNS.NewCachingResolver(net.DefaultResolver)
+	}
+
 	return &bridgeCfg{
 		Client:              MQTT.NewClient(createClientOptions(*broker, *user, *password, *clean, *topic)),
 		KeepRunning:         make(chan bool),