feat: optimise get server ip (#20)

* feat: optimise get server ip

* feat: test ServerIP

src/common/config/config.go

@@ -1,8 +1,17 @@
 package config
 
 import (
-	"gopkg.in/yaml.v3"
 	"io/ioutil"
+	"path/filepath"
+	"runtime"
+
+	"gopkg.in/yaml.v3"
+)
+
+var (
+	_, b, _, _ = runtime.Caller(0)
+	// Root folder of this project
+	Root = filepath.Join(filepath.Dir(b), "../../..")
 )
 
 var Config config
@@ -147,14 +156,14 @@ type config struct {
 }
 
 func init() {
-	bytes, err := ioutil.ReadFile("../config/config.yaml")
+	// if we cd Open-IM-Server/src/utils and run go test
+	// it will panic cannot find config/config.yaml
+	bytes, err := ioutil.ReadFile(Root + "/config/config.yaml")
 	if err != nil {
 		panic(err)
-		return
 	}
 	if err = yaml.Unmarshal(bytes, &Config); err != nil {
 		panic(err)
-		return
 	}
 
 }

src/utils/get_server_ip.go

@@ -13,23 +13,14 @@ func init() {
 		ServerIP = config.Config.ServerIP
 		return
 	}
-	//fixme Get the ip of the local network card
-	netInterfaces, err := net.Interfaces()
+
+	// see https://gist.github.com/jniltinho/9787946#gistcomment-3019898
+	conn, err := net.Dial("udp", "8.8.8.8:80")
 	if err != nil {
 		panic(err)
 	}
-	for i := 0; i < len(netInterfaces); i++ {
-		//Exclude useless network cards by judging the net.flag Up flag
-		if (netInterfaces[i].Flags & net.FlagUp) != 0 {
-			address, _ := netInterfaces[i].Addrs()
-			for _, addr := range address {
-				if ipNet, ok := addr.(*net.IPNet); ok && !ipNet.IP.IsLoopback() {
-					if ipNet.IP.To4() != nil {
-						ServerIP = ipNet.IP.String()
-						return
-					}
-				}
-			}
-		}
-	}
+
+	defer conn.Close()
+	localAddr := conn.LocalAddr().(*net.UDPAddr)
+	ServerIP = localAddr.IP.String()
 }

src/utils/get_server_ip_test.go

@@ -0,0 +1,12 @@
+package utils
+
+import (
+	"net"
+	"testing"
+)
+
+func TestServerIP(t *testing.T) {
+	if net.ParseIP(ServerIP) == nil {
+		t.Fail()
+	}
+}