[c] Fix local ip fetch and add test

net/client.go

@@ -154,8 +154,8 @@ func ExternalInterfaceAddr() ([]string, error) {
 		return nil, err
 	}
 
-	var extAddrs = make([]string, len(addrs))
-	var localhostAddrs = make([]string, 1)
+	var extAddrs = make([]string, 0)
+	var localhostAddrs = make([]string, 0)
 
 	for _, a := range addrs {
 		if strings.ContainsRune(a.String(), ':') {

net/net_test.go

@@ -3,6 +3,7 @@ package net
 import (
 	"fmt"
 	"net"
+	"regexp"
 	"testing"
 	"time"
 
@@ -253,3 +254,19 @@ func Example() {
 	// 42
 	// 43
 }
+
+// INTERFACE TEST
+
+func TestExternalInterfaces(t *testing.T) {
+	ips, err := ExternalInterfaceAddr()
+	if err != nil {
+		panic("Cannot read interfaces config")
+	}
+
+	isAnIpV4 := regexp.MustCompile("^(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?).(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?).(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?).(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)$")
+	for _, ip := range ips {
+		if !isAnIpV4.MatchString(ip) {
+			panic(ip + " is not a valid IPv4!")
+		}
+	}
+}