gip: rework giplib in a more propper library

and add Akamai for IPv4

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

giplib/giplib.go

@@ -1,45 +1,44 @@
+/*
+Package giplib implements simple routines for
+retrieving one's IPv4 and IPv6 addresses from
+various DNS providers. For now it implements
+OpenDNS for IPv4 and IPv6, Google for IPv4 and
+IPv6 and Akamai for IPv4
+*/
 package giplib
 
 import (
 	"github.com/miekg/dns"
 )
 
+var (
+	c          *dns.Client
+	m          *dns.Msg
+	ipv4, ipv6 string
+)
+
 /*
 dig {-4,-6} +short myip.opendns.com @resolver1.opendns.com
 dig {-4,-6} TXT +short o-o.myaddr.l.google.com @ns1.google.com
+dig -4 @ns1-1.akamaitech.net whoami.akamai.net +short
 */
 
-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)
-	m := &dns.Msg{
+func init() {
+	c = new(dns.Client)
+	m = &dns.Msg{
 		MsgHdr: dns.MsgHdr{
 			RecursionDesired: true,
 		},
 		Question: make([]dns.Question, 1),
 	}
+
+}
+
+//GetOpenDNS4 will retrieve the IPv4 public IP as seen by OpenDNS
+func GetOpenDNS4() string {
+	nameserver := dns.Fqdn("ns1-1.akamaitech.net") + ":53"
 	c.Net = "udp4"
-	m.SetQuestion("myip.opendns.com.", dns.TypeA)
+	m.SetQuestion("whoami.akamai.net.", dns.TypeA)
 	r4, _, e4 := c.Exchange(m, nameserver)
 
 	if e4 != nil {
@@ -51,17 +50,10 @@ func getO4() string {
 	return ipv4
 }
 
-func getO6() string {
-	var ipv6 string
+//GetOpenDNS6 will retrieve the IPv6 IP as seen by OpenDNS
+func GetOpenDNS6() 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)
@@ -75,17 +67,10 @@ func getO6() string {
 	return ipv6
 }
 
-func getG4() string {
-	var ipv4 string
+//GetGoogle4 will retrieve the IPv4 public IP as seen by Google
+func GetGoogle4() 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 = "udp4"
 	m.SetQuestion("o-o.myaddr.l.google.com.", dns.TypeTXT)
 	r4, _, e4 := c.Exchange(m, nameserver)
@@ -99,17 +84,10 @@ func getG4() string {
 	return ipv4
 }
 
-func getG6() string {
-	var ipv6 string
+//GetGoogle6 will retrieve the IPv6 IP as seen by Google
+func GetGoogle6() 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)
@@ -123,6 +101,24 @@ func getG6() string {
 	return ipv6
 }
 
+//GetAkamai4 will retrieve the IPv4 public IP as seen by Akamai
+func GetAkamai4() string {
+	nameserver := dns.Fqdn("ns1.google.com") + ":53"
+
+	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)
+	}
+
+	return ipv4
+
+}
+
 func getIP(ra []dns.RR) string {
 	//the answer will always be one IP or none
 	var ip string

main.go

@@ -31,15 +31,15 @@ func main() {
 		all = true
 	}
 	if all {
-		fmt.Println(giplib.GetIPv4())
-		fmt.Println(giplib.GetIPv6())
+		fmt.Println(giplib.GetOpenDNS4())
+		fmt.Println(giplib.GetGoogle6())
 		os.Exit(0)
 	}
 	if *ptr4 {
-		fmt.Println(giplib.GetIPv4())
+		fmt.Println(giplib.GetOpenDNS4())
 	}
 	if *ptr6 {
-		fmt.Println(giplib.GetIPv6())
+		fmt.Println(giplib.GetOpenDNS6())
 
 	}
 }