feat(simapp/v2): Testnet init command (#20866)

server/v2/util.go

@@ -2,7 +2,9 @@ package serverv2
 
 import (
 	"context"
+	"errors"
 	"fmt"
+	"net"
 
 	"github.com/spf13/cobra"
 	"github.com/spf13/viper"
@@ -47,3 +49,59 @@ func GetLoggerFromCmd(cmd *cobra.Command) corelog.Logger {
 
 	return logger
 }
+
+// ExternalIP https://stackoverflow.com/questions/23558425/how-do-i-get-the-local-ip-address-in-go
+// TODO there must be a better way to get external IP
+func ExternalIP() (string, error) {
+	ifaces, err := net.Interfaces()
+	if err != nil {
+		return "", err
+	}
+
+	for _, iface := range ifaces {
+		if skipInterface(iface) {
+			continue
+		}
+		addrs, err := iface.Addrs()
+		if err != nil {
+			return "", err
+		}
+
+		for _, addr := range addrs {
+			ip := addrToIP(addr)
+			if ip == nil || ip.IsLoopback() {
+				continue
+			}
+			ip = ip.To4()
+			if ip == nil {
+				continue // not an ipv4 address
+			}
+			return ip.String(), nil
+		}
+	}
+	return "", errors.New("are you connected to the network?")
+}
+
+func skipInterface(iface net.Interface) bool {
+	if iface.Flags&net.FlagUp == 0 {
+		return true // interface down
+	}
+
+	if iface.Flags&net.FlagLoopback != 0 {
+		return true // loopback interface
+	}
+
+	return false
+}
+
+func addrToIP(addr net.Addr) net.IP {
+	var ip net.IP
+
+	switch v := addr.(type) {
+	case *net.IPNet:
+		ip = v.IP
+	case *net.IPAddr:
+		ip = v.IP
+	}
+	return ip
+}