sslip.io: lean main.go

Moved much of the processing of DNS messages into the library. Testing a
library is easier than testing `main`, so I like to keep a lean
`main`.

src/main.go

@@ -1,12 +1,10 @@
 package main
 
 import (
-	"encoding/json"
 	"github.com/cunnie/sslip.io/src/xip"
 	"log"
+	"net"
 )
-import "net"
-import "golang.org/x/net/dns/dnsmessage"
 
 func main() {
 	conn, err := net.ListenUDP("udp", &net.UDPAddr{Port: 53})
@@ -14,29 +12,20 @@ func main() {
 		log.Fatal(err.Error())
 	}
 
-	var m dnsmessage.Message
+	query := make([]byte, 512)
-	buf := make([]byte, 512)
 
 	for {
-		_, _, err := conn.ReadFromUDP(buf)
+		_, addr, err := conn.ReadFromUDP(query)
 		if err != nil {
 			log.Println(err.Error())
 			break
 		}
-		err = m.Unpack(buf)
+
+		response, err := xip.QueryResponse(query)
 		if err != nil {
 			log.Println(err.Error())
 			break
 		}
-		for _, question := range m.Questions {
+		_, err = conn.WriteToUDP(response, addr)
-			jsonQuestion, err := json.Marshal(question)
-			if err != nil {
-				log.Println(err.Error())
-			}
-			answer, _ := xip.NameToA(question.GoString())
-			jsonAnswer, err := json.Marshal(answer)
-			log.Println(jsonQuestion)
-			log.Println(jsonAnswer)
-		}
 	}
 }

src/xip/xip.go

@@ -1,8 +1,10 @@
 package xip
 
 import (
+	"encoding/json"
 	"errors"
 	"golang.org/x/net/dns/dnsmessage"
+	"log"
 	"net"
 	"regexp"
 	"strings"
@@ -12,6 +14,26 @@ import (
 var ipv4RE= regexp.MustCompile(`(^|[.-])(((25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9])[.-]){3,3}(25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9]))($|[.-])`)
 var ipv6RE= regexp.MustCompile(`(^|[.-])(([0-9a-fA-F]{1,4}-){7,7}[0-9a-fA-F]{1,4}|([0-9a-fA-F]{1,4}-){1,7}-|([0-9a-fA-F]{1,4}-){1,6}-[0-9a-fA-F]{1,4}|([0-9a-fA-F]{1,4}-){1,5}(-[0-9a-fA-F]{1,4}){1,2}|([0-9a-fA-F]{1,4}-){1,4}(-[0-9a-fA-F]{1,4}){1,3}|([0-9a-fA-F]{1,4}-){1,3}(-[0-9a-fA-F]{1,4}){1,4}|([0-9a-fA-F]{1,4}-){1,2}(-[0-9a-fA-F]{1,4}){1,5}|[0-9a-fA-F]{1,4}-((-[0-9a-fA-F]{1,4}){1,6})|-((-[0-9a-fA-F]{1,4}){1,7}|-)|fe80-(-[0-9a-fA-F]{0,4}){0,4}%[0-9a-zA-Z]{1,}|--(ffff(-0{1,4}){0,1}-){0,1}((25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9])\.){3,3}(25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9])|([0-9a-fA-F]{1,4}-){1,4}-((25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9])\.){3,3}(25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9]))($|[.-])`)
 
+func QueryResponse(query []byte) ([]byte, error) {
+	var m dnsmessage.Message
+
+	err := m.Unpack(query)
+	if err != nil {
+		return nil, err
+	}
+	for _, question := range m.Questions {
+		jsonQuestion, err := json.Marshal(question)
+		if err != nil {
+			return nil, err
+		}
+		answer, _ := NameToA(question.GoString())
+		jsonAnswer, err := json.Marshal(answer)
+		log.Println(jsonQuestion)
+		log.Println(jsonAnswer)
+	}
+	return []byte{0x0}, nil
+}
+
 func NameToA (fqdnString string) (dnsmessage.AResource, error) {
 	fqdn:=[]byte(fqdnString)
 	if ! ipv4RE.Match(fqdn) {