giplib: separate functions in lib and app

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

README.md

@@ -1,3 +1,8 @@
 # gip
 
 Find your public IP
+gip will print your public IPv4 followed by a tab and your public IPv6.
+If either is missing they will be replaced by "". Please note that due 
+to their way usage the IPv4 will most probably be the public IP of your
+gateway while the IPv6 will be the public IP of the computer gip is run 
+on.

gip.go

@@ -1,68 +0,0 @@
-package main
-
-import (
-	"fmt"
-
-	"github.com/miekg/dns"
-)
-
-/*
-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 get4(c *dns.Client, m *dns.Msg, nameserver string) (*dns.Msg, error) {
-	c.Net = "udp4"
-	m.SetQuestion("myip.opendns.com.", dns.TypeA)
-
-	r, _, err := c.Exchange(m, nameserver)
-	return r, err
-}
-
-func get6(c *dns.Client, m *dns.Msg, nameserver string) (*dns.Msg, error) {
-	c.Net = "udp6"
-	m.SetQuestion("myip.opendns.com.", dns.TypeAAAA)
-
-	r, _, err := c.Exchange(m, nameserver)
-	return r, err
-
-}
-
-func printIP(ra []dns.RR) []string {
-	var ips []string
-	for _, ansa := range ra {
-		switch ansb := ansa.(type) {
-		case *dns.A:
-			ips = append(ips, ansb.A.String())
-		case *dns.AAAA:
-			ips = append(ips, ansb.AAAA.String())
-		}
-	}
-	return ips
-}
-
-func main() {
-	nameserver := dns.Fqdn("resolver1.opendns.com") + ":53"
-
-	c := new(dns.Client)
-	c.Net = "udp4"
-	m := &dns.Msg{
-		MsgHdr: dns.MsgHdr{
-			RecursionDesired: true,
-		},
-		Question: make([]dns.Question, 1),
-	}
-	r4, err := get4(c, m, nameserver)
-	if err != nil {
-		fmt.Println(err)
-	} else {
-		fmt.Println(printIP(r4.Answer))
-	}
-	r6, e6 := get6(c, m, nameserver)
-	if err != nil {
-		fmt.Println(e6)
-	} else {
-		fmt.Println(printIP(r6.Answer))
-	}
-
-}

giplib/giplib.go

@@ -0,0 +1,142 @@
+package giplib
+
+import (
+	"github.com/miekg/dns"
+)
+
+/*
+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 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{
+		MsgHdr: dns.MsgHdr{
+			RecursionDesired: true,
+		},
+		Question: make([]dns.Question, 1),
+	}
+	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)
+	}
+
+	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 ipv6
+}
+
+func getG4() string {
+	var ipv4 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)
+
+	if e4 != nil {
+		ipv4 = ""
+	} else {
+		ipv4 = getIP(r4.Answer)
+	}
+
+	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 ipv6
+}
+
+func getIP(ra []dns.RR) string {
+	//the answer will always be one IP or none
+	var ip string
+	for _, ansa := range ra {
+		switch ansb := ansa.(type) {
+		case *dns.A:
+			ip = ansb.A.String()
+		case *dns.AAAA:
+			ip = ansb.AAAA.String()
+		case *dns.TXT:
+			// we always expect only one IP in the field
+			ip = ansb.Txt[0]
+		}
+	}
+
+	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())
+
+	}
+}