New whatismydns feature (#29)

server/dns.go

@@ -0,0 +1,48 @@
+package server
+
+import (
+	"context"
+	"log"
+	"strconv"
+
+	"github.com/miekg/dns"
+)
+
+const port = 53
+
+type DNS struct {
+	server  *dns.Server
+	handler *dns.Handler
+	ctx     context.Context
+}
+
+func NewDNSServer(ctx context.Context, handler dns.Handler) *DNS {
+	return &DNS{
+		handler: &handler,
+		ctx:     ctx,
+	}
+}
+
+func (d *DNS) Start() {
+	d.server = &dns.Server{
+		Addr:    ":" + strconv.Itoa(port),
+		Net:     "udp",
+		Handler: *d.handler,
+		// UDPSize:   65535,
+		// ReusePort: true,
+	}
+
+	log.Printf("Starting DNS server listening on :%d (udp)", port)
+	go func() {
+		if err := d.server.ListenAndServe(); err != nil {
+			log.Fatal(err)
+		}
+	}()
+}
+
+func (d *DNS) Stop() {
+	log.Printf("Stopping DNS server...")
+	if err := d.server.Shutdown(); err != nil {
+		log.Printf("DNS server forced to shutdown: %s", err)
+	}
+}