giplib: separate functions in lib and app

Signed-off-by: Nagy Károly Gábriel <k@jpi.io>

giplib/giplib.go

@@ -1,9 +1,7 @@
-package main
+package giplib
 
 import (
-	"fmt"
 	"github.com/miekg/dns"
-	"os"
 )
 
 /*
@@ -11,7 +9,26 @@ dig {-4,-6} +short myip.opendns.com @resolver1.opendns.com
 dig {-4,-6} TXT +short o-o.myaddr.l.google.com @ns1.google.com
 */
 
-func getO() (ipv4 string, ipv6 string) {
+func GetIPv4() string {
+	o4 := getO4()
+	g4 := getG4()
+	if o4 == g4 {
+		return o4
+	}
+	return ""
+}
+
+func GetIPv6() string {
+	o6 := getO6()
+	g6 := getG6()
+	if o6 == g6 {
+		return o6
+	}
+	return ""
+}
+
+func getO4() string {
+	var ipv4 string
 	nameserver := dns.Fqdn("resolver1.opendns.com") + ":53"
 
 	c := new(dns.Client)
@@ -21,28 +38,45 @@ func getO() (ipv4 string, ipv6 string) {
 		},
 		Question: make([]dns.Question, 1),
 	}
-	// get IPv4 first
 	c.Net = "udp4"
 	m.SetQuestion("myip.opendns.com.", dns.TypeA)
 	r4, _, e4 := c.Exchange(m, nameserver)
+
 	if e4 != nil {
 		ipv4 = ""
 	} else {
 		ipv4 = getIP(r4.Answer)
 	}
-	// now IPv6
+
+	return ipv4
+}
+
+func getO6() string {
+	var ipv6 string
+	nameserver := dns.Fqdn("resolver1.opendns.com") + ":53"
+
+	c := new(dns.Client)
+	m := &dns.Msg{
+		MsgHdr: dns.MsgHdr{
+			RecursionDesired: true,
+		},
+		Question: make([]dns.Question, 1),
+	}
 	c.Net = "udp6"
 	m.SetQuestion("myip.opendns.com.", dns.TypeAAAA)
 	r6, _, e6 := c.Exchange(m, nameserver)
+
 	if e6 != nil {
 		ipv6 = ""
 	} else {
 		ipv6 = getIP(r6.Answer)
 	}
-	return ipv4, ipv6
+
+	return ipv6
 }
 
-func getG() (ipv4 string, ipv6 string) {
+func getG4() string {
+	var ipv4 string
 	nameserver := dns.Fqdn("ns1.google.com") + ":53"
 
 	c := new(dns.Client)
@@ -52,25 +86,41 @@ func getG() (ipv4 string, ipv6 string) {
 		},
 		Question: make([]dns.Question, 1),
 	}
-	// get IPv4 first
 	c.Net = "udp4"
 	m.SetQuestion("o-o.myaddr.l.google.com.", dns.TypeTXT)
 	r4, _, e4 := c.Exchange(m, nameserver)
+
 	if e4 != nil {
 		ipv4 = ""
 	} else {
 		ipv4 = getIP(r4.Answer)
 	}
-	// now IPv6
+
+	return ipv4
+}
+
+func getG6() string {
+	var ipv6 string
+	nameserver := dns.Fqdn("ns1.google.com") + ":53"
+
+	c := new(dns.Client)
+	m := &dns.Msg{
+		MsgHdr: dns.MsgHdr{
+			RecursionDesired: true,
+		},
+		Question: make([]dns.Question, 1),
+	}
 	c.Net = "udp6"
 	m.SetQuestion("o-o.myaddr.l.google.com.", dns.TypeTXT)
 	r6, _, e6 := c.Exchange(m, nameserver)
+
 	if e6 != nil {
 		ipv6 = ""
 	} else {
 		ipv6 = getIP(r6.Answer)
 	}
-	return ipv4, ipv6
+
+	return ipv6
 }
 
 func getIP(ra []dns.RR) string {
@@ -87,26 +137,6 @@ func getIP(ra []dns.RR) string {
 			ip = ansb.Txt[0]
 		}
 	}
-	return ip
-}
 
-func main() {
-	var ipv4, ipv6 string
-	exit := 0
-	o4, o6 := getO()
-	g4, g6 := getG()
-	if o4 == g4 {
-		ipv4 = o4
-	} else {
-		ipv4 = ""
-		exit = 111
-	}
-	if o6 == g6 {
-		ipv6 = o6
-	} else {
-		ipv6 = ""
-		exit = 111
-	}
-	fmt.Printf("%s\t%s\n", ipv4, ipv6)
-	os.Exit(exit)
+	return ip
 }

main.go

@@ -0,0 +1,45 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+	"git.jpi.io/karasz/gip/giplib"
+	"os"
+)
+
+var (
+	//Version contains the git hashtag injected by make
+	Version = "N/A"
+	//BuildTime contains the build timestamp injected by make
+	BuildTime = "N/A"
+)
+
+func main() {
+	var all bool
+	ptr4 := flag.Bool("4", false, "return only IPv4")
+	ptr6 := flag.Bool("6", false, "return only IPv6")
+	version := flag.Bool("v", false, "return version")
+
+	flag.Parse()
+
+	if *version {
+		fmt.Println(Version, " built on ", BuildTime)
+		os.Exit(0)
+	}
+
+	if *ptr4 == *ptr6 {
+		all = true
+	}
+	if all {
+		fmt.Println(giplib.GetIPv4())
+		fmt.Println(giplib.GetIPv6())
+		os.Exit(0)
+	}
+	if *ptr4 {
+		fmt.Println(giplib.GetIPv4())
+	}
+	if *ptr6 {
+		fmt.Println(giplib.GetIPv6())
+
+	}
+}