Handle other network cases

- Fails to start app if user is not connected to any network
- Falls back to looping over interfaces if user is not connected
  to internet

internal/ui/launch.go

@@ -35,6 +35,24 @@ func NewUI() *UI {
 func (u *UI) Launch() error {
 	log := logger.New()
 
+	userIP, cidr, err := util.GetNetworkInfo()
+
+	if err != nil {
+		log.Fatal().Err(err).Msg("failed to get default network info")
+	}
+
+	appCore, err := util.CreateNewAppCore(*cidr)
+
+	if err != nil {
+		log.Fatal().Err(err).Msg("failed to create app core")
+	}
+
+	allConfigs, err := appCore.GetConfigs()
+
+	if err != nil {
+		log.Fatal().Err(err).Msg("failed to retrieve configs")
+	}
+
 	level := zerolog.GlobalLevel()
 
 	if level != zerolog.Disabled {
@@ -63,24 +81,6 @@ func (u *UI) Launch() error {
 		}
 	}
 
-	userIP, cidr, err := util.GetNetworkInfo()
-
-	if err != nil {
-		log.Fatal().Err(err).Msg("failed to get default network info")
-	}
-
-	appCore, err := util.CreateNewAppCore(*cidr)
-
-	if err != nil {
-		log.Fatal().Err(err).Msg("failed to create app core")
-	}
-
-	allConfigs, err := appCore.GetConfigs()
-
-	if err != nil {
-		log.Fatal().Err(err).Msg("failed to retrieve configs")
-	}
-
 	u.view = newView(*userIP, allConfigs, appCore)
 
 	os.Stdout, _ = os.Open(os.DevNull)

internal/util/network.go

@@ -50,25 +50,57 @@ func getIPNetByIP(ip net.IP) (*net.IPNet, error) {
 // GetNetworkInfo returns userIP and cidr block for preferred
 // outbound ip of this machine
 func GetNetworkInfo() (*string, *string, error) {
+	// udp doesn't make a full connection and will find the default ip
+	// that traffic will use if say 2 are configured (wired and wireless)
 	conn, err := net.Dial("udp", "8.8.8.8:80")
 
+	var foundIP net.IP
+
 	if err != nil {
-		return nil, nil, err
-	}
+		// resort to looping through interfaces
+		ifaces, err := net.Interfaces()
+
+		if err != nil {
+			return nil, nil, err
+		}
 
-	defer conn.Close()
+	OUTER:
+		for _, i := range ifaces {
+			addrs, err := i.Addrs()
 
-	localAddr := conn.LocalAddr().(*net.UDPAddr)
+			if err != nil {
+				continue
+			}
+
+			for _, addr := range addrs {
+				switch v := addr.(type) {
+				case *net.IPAddr:
+					if !v.IP.IsLoopback() {
+						foundIP = v.IP
+						break OUTER
+					}
+				}
+			}
+		}
+
+		if foundIP == nil {
+			return nil, nil, fmt.Errorf("failed to find IP address for this machine")
+		}
+	} else {
+		defer conn.Close()
+		localAddr := conn.LocalAddr().(*net.UDPAddr)
+		foundIP = localAddr.IP
+	}
 
-	ipnet, err := getIPNetByIP(localAddr.IP)
+	ipnet, err := getIPNetByIP(foundIP)
 
 	if err != nil {
 		return nil, nil, err
 	}
 
 	size, _ := ipnet.Mask.Size()
 
-	ipCidr := fmt.Sprintf("%s/%d", localAddr.IP, size)
+	ipCidr := fmt.Sprintf("%s/%d", foundIP, size)
 
 	ip, ipnet, err := net.ParseCIDR(ipCidr)
 	if err != nil {
@@ -84,7 +116,7 @@ func GetNetworkInfo() (*string, *string, error) {
 		}
 	}
 
-	userIP := localAddr.IP.String()
+	userIP := foundIP.String()
 	cidr := fmt.Sprintf("%s/%d", firstCidrIP, size)
 
 	return &userIP, &cidr, nil