WIP

router/dns/dns.go

@@ -0,0 +1,111 @@
+package dns
+
+import (
+	"fmt"
+	"log"
+	"net"
+	"strings"
+
+	"github.com/miekg/dns"
+	"github.com/play-with-docker/play-with-docker/config"
+)
+
+func DnsRequest(w dns.ResponseWriter, r *dns.Msg) {
+	if len(r.Question) > 0 && config.NameFilter.MatchString(r.Question[0].Name) {
+		// this is something we know about and we should try to handle
+		question := r.Question[0].Name
+
+		match := config.NameFilter.FindStringSubmatch(question)
+
+		ip := strings.Replace(match[1], "-", ".", -1)
+
+		m := new(dns.Msg)
+		m.SetReply(r)
+		m.Authoritative = true
+		m.RecursionAvailable = true
+		a, err := dns.NewRR(fmt.Sprintf("%s 60 IN A %s", question, ip))
+		if err != nil {
+			log.Fatal(err)
+		}
+		m.Answer = append(m.Answer, a)
+		w.WriteMsg(m)
+		return
+	} else if len(r.Question) > 0 && config.AliasFilter.MatchString(r.Question[0].Name) {
+		// this is something we know about and we should try to handle
+		question := r.Question[0].Name
+
+		match := config.AliasFilter.FindStringSubmatch(question)
+
+		i := core.InstanceFindByAlias(match[2], match[1])
+
+		m := new(dns.Msg)
+		m.SetReply(r)
+		m.Authoritative = true
+		m.RecursionAvailable = true
+		a, err := dns.NewRR(fmt.Sprintf("%s 60 IN A %s", question, i.IP))
+		if err != nil {
+			log.Fatal(err)
+		}
+		m.Answer = append(m.Answer, a)
+		w.WriteMsg(m)
+		return
+	} else {
+		if len(r.Question) > 0 {
+			question := r.Question[0].Name
+
+			if question == "localhost." {
+				log.Printf("Not a PWD host. Asked for [localhost.] returning automatically [127.0.0.1]\n")
+				m := new(dns.Msg)
+				m.SetReply(r)
+				m.Authoritative = true
+				m.RecursionAvailable = true
+				a, err := dns.NewRR(fmt.Sprintf("%s 60 IN A 127.0.0.1", question))
+				if err != nil {
+					log.Fatal(err)
+				}
+				m.Answer = append(m.Answer, a)
+				w.WriteMsg(m)
+				return
+			}
+
+			log.Printf("Not a PWD host. Looking up [%s]\n", question)
+			ips, err := net.LookupIP(question)
+			if err != nil {
+				// we have no information about this and we are not a recursive dns server, so we just fail so the client can fallback to the next dns server it has configured
+				w.Close()
+				// dns.HandleFailed(w, r)
+				return
+			}
+			log.Printf("Not a PWD host. Looking up [%s] got [%s]\n", question, ips)
+			m := new(dns.Msg)
+			m.SetReply(r)
+			m.Authoritative = true
+			m.RecursionAvailable = true
+			for _, ip := range ips {
+				ipv4 := ip.To4()
+				if ipv4 == nil {
+					a, err := dns.NewRR(fmt.Sprintf("%s 60 IN AAAA %s", question, ip.String()))
+					if err != nil {
+						log.Fatal(err)
+					}
+					m.Answer = append(m.Answer, a)
+				} else {
+					a, err := dns.NewRR(fmt.Sprintf("%s 60 IN A %s", question, ipv4.String()))
+					if err != nil {
+						log.Fatal(err)
+					}
+					m.Answer = append(m.Answer, a)
+				}
+			}
+			w.WriteMsg(m)
+			return
+
+		} else {
+			log.Printf("Not a PWD host. Got DNS without any question\n")
+			// we have no information about this and we are not a recursive dns server, so we just fail so the client can fallback to the next dns server it has configured
+			w.Close()
+			// dns.HandleFailed(w, r)
+			return
+		}
+	}
+}