dns: init

1 files changed, 54 insertions, 0 deletions

diff --git a/dns/main.go b/dns/main.go
new file mode 100644
index 0000000..b3adfca
--- /dev/null
+++ b/dns/main.go
@@ -0,0 +1,54 @@
+package dns
+
+import (
+	"log"
+	"net"
+
+	"github.com/miekg/dns"
+)
+
+type Dns struct {
+	server dns.Server
+	config *dns.ClientConfig
+}
+
+func (d *Dns) ServeDNS(w dns.ResponseWriter, req *dns.Msg) {
+	var resp *dns.Msg
+	var err error
+	client := new(dns.Client)
+
+	req.RecursionDesired = true;
+	for _, upstream := range d.config.Servers {
+		resp, _, err = client.Exchange(req, net.JoinHostPort(upstream, d.config.Port))
+		if err == nil {
+			break
+		}
+
+		log.Printf("dns query: %s", err)
+	}
+
+	w.WriteMsg(resp)
+}
+
+func New() (*Dns, error) {
+	var d Dns
+	var err error
+
+	d.server = dns.Server{
+		Net: "udp",
+		ReusePort: true,
+		Handler: &d,
+	}
+
+	d.config, err = dns.ClientConfigFromFile("/etc/resolv.conf")
+	if err != nil {
+		log.Printf("reading resolve.conf: %s", err)
+		return nil, err
+	}
+
+	return &d, nil
+}
+
+func (d *Dns) Run() {
+	d.server.ListenAndServe()
+}